root/tools/include/uapi/linux/bpf.h

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DEFINITIONS

This source file includes following definitions.
  1. __BPF_FUNC_MAPPER

   1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
   2 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of version 2 of the GNU General Public
   6  * License as published by the Free Software Foundation.
   7  */
   8 #ifndef _UAPI__LINUX_BPF_H__
   9 #define _UAPI__LINUX_BPF_H__
  10 
  11 #include <linux/types.h>
  12 #include <linux/bpf_common.h>
  13 
  14 /* Extended instruction set based on top of classic BPF */
  15 
  16 /* instruction classes */
  17 #define BPF_JMP32       0x06    /* jmp mode in word width */
  18 #define BPF_ALU64       0x07    /* alu mode in double word width */
  19 
  20 /* ld/ldx fields */
  21 #define BPF_DW          0x18    /* double word (64-bit) */
  22 #define BPF_XADD        0xc0    /* exclusive add */
  23 
  24 /* alu/jmp fields */
  25 #define BPF_MOV         0xb0    /* mov reg to reg */
  26 #define BPF_ARSH        0xc0    /* sign extending arithmetic shift right */
  27 
  28 /* change endianness of a register */
  29 #define BPF_END         0xd0    /* flags for endianness conversion: */
  30 #define BPF_TO_LE       0x00    /* convert to little-endian */
  31 #define BPF_TO_BE       0x08    /* convert to big-endian */
  32 #define BPF_FROM_LE     BPF_TO_LE
  33 #define BPF_FROM_BE     BPF_TO_BE
  34 
  35 /* jmp encodings */
  36 #define BPF_JNE         0x50    /* jump != */
  37 #define BPF_JLT         0xa0    /* LT is unsigned, '<' */
  38 #define BPF_JLE         0xb0    /* LE is unsigned, '<=' */
  39 #define BPF_JSGT        0x60    /* SGT is signed '>', GT in x86 */
  40 #define BPF_JSGE        0x70    /* SGE is signed '>=', GE in x86 */
  41 #define BPF_JSLT        0xc0    /* SLT is signed, '<' */
  42 #define BPF_JSLE        0xd0    /* SLE is signed, '<=' */
  43 #define BPF_CALL        0x80    /* function call */
  44 #define BPF_EXIT        0x90    /* function return */
  45 
  46 /* Register numbers */
  47 enum {
  48         BPF_REG_0 = 0,
  49         BPF_REG_1,
  50         BPF_REG_2,
  51         BPF_REG_3,
  52         BPF_REG_4,
  53         BPF_REG_5,
  54         BPF_REG_6,
  55         BPF_REG_7,
  56         BPF_REG_8,
  57         BPF_REG_9,
  58         BPF_REG_10,
  59         __MAX_BPF_REG,
  60 };
  61 
  62 /* BPF has 10 general purpose 64-bit registers and stack frame. */
  63 #define MAX_BPF_REG     __MAX_BPF_REG
  64 
  65 struct bpf_insn {
  66         __u8    code;           /* opcode */
  67         __u8    dst_reg:4;      /* dest register */
  68         __u8    src_reg:4;      /* source register */
  69         __s16   off;            /* signed offset */
  70         __s32   imm;            /* signed immediate constant */
  71 };
  72 
  73 /* Key of an a BPF_MAP_TYPE_LPM_TRIE entry */
  74 struct bpf_lpm_trie_key {
  75         __u32   prefixlen;      /* up to 32 for AF_INET, 128 for AF_INET6 */
  76         __u8    data[0];        /* Arbitrary size */
  77 };
  78 
  79 struct bpf_cgroup_storage_key {
  80         __u64   cgroup_inode_id;        /* cgroup inode id */
  81         __u32   attach_type;            /* program attach type */
  82 };
  83 
  84 /* BPF syscall commands, see bpf(2) man-page for details. */
  85 enum bpf_cmd {
  86         BPF_MAP_CREATE,
  87         BPF_MAP_LOOKUP_ELEM,
  88         BPF_MAP_UPDATE_ELEM,
  89         BPF_MAP_DELETE_ELEM,
  90         BPF_MAP_GET_NEXT_KEY,
  91         BPF_PROG_LOAD,
  92         BPF_OBJ_PIN,
  93         BPF_OBJ_GET,
  94         BPF_PROG_ATTACH,
  95         BPF_PROG_DETACH,
  96         BPF_PROG_TEST_RUN,
  97         BPF_PROG_GET_NEXT_ID,
  98         BPF_MAP_GET_NEXT_ID,
  99         BPF_PROG_GET_FD_BY_ID,
 100         BPF_MAP_GET_FD_BY_ID,
 101         BPF_OBJ_GET_INFO_BY_FD,
 102         BPF_PROG_QUERY,
 103         BPF_RAW_TRACEPOINT_OPEN,
 104         BPF_BTF_LOAD,
 105         BPF_BTF_GET_FD_BY_ID,
 106         BPF_TASK_FD_QUERY,
 107         BPF_MAP_LOOKUP_AND_DELETE_ELEM,
 108         BPF_MAP_FREEZE,
 109         BPF_BTF_GET_NEXT_ID,
 110 };
 111 
 112 enum bpf_map_type {
 113         BPF_MAP_TYPE_UNSPEC,
 114         BPF_MAP_TYPE_HASH,
 115         BPF_MAP_TYPE_ARRAY,
 116         BPF_MAP_TYPE_PROG_ARRAY,
 117         BPF_MAP_TYPE_PERF_EVENT_ARRAY,
 118         BPF_MAP_TYPE_PERCPU_HASH,
 119         BPF_MAP_TYPE_PERCPU_ARRAY,
 120         BPF_MAP_TYPE_STACK_TRACE,
 121         BPF_MAP_TYPE_CGROUP_ARRAY,
 122         BPF_MAP_TYPE_LRU_HASH,
 123         BPF_MAP_TYPE_LRU_PERCPU_HASH,
 124         BPF_MAP_TYPE_LPM_TRIE,
 125         BPF_MAP_TYPE_ARRAY_OF_MAPS,
 126         BPF_MAP_TYPE_HASH_OF_MAPS,
 127         BPF_MAP_TYPE_DEVMAP,
 128         BPF_MAP_TYPE_SOCKMAP,
 129         BPF_MAP_TYPE_CPUMAP,
 130         BPF_MAP_TYPE_XSKMAP,
 131         BPF_MAP_TYPE_SOCKHASH,
 132         BPF_MAP_TYPE_CGROUP_STORAGE,
 133         BPF_MAP_TYPE_REUSEPORT_SOCKARRAY,
 134         BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE,
 135         BPF_MAP_TYPE_QUEUE,
 136         BPF_MAP_TYPE_STACK,
 137         BPF_MAP_TYPE_SK_STORAGE,
 138         BPF_MAP_TYPE_DEVMAP_HASH,
 139 };
 140 
 141 /* Note that tracing related programs such as
 142  * BPF_PROG_TYPE_{KPROBE,TRACEPOINT,PERF_EVENT,RAW_TRACEPOINT}
 143  * are not subject to a stable API since kernel internal data
 144  * structures can change from release to release and may
 145  * therefore break existing tracing BPF programs. Tracing BPF
 146  * programs correspond to /a/ specific kernel which is to be
 147  * analyzed, and not /a/ specific kernel /and/ all future ones.
 148  */
 149 enum bpf_prog_type {
 150         BPF_PROG_TYPE_UNSPEC,
 151         BPF_PROG_TYPE_SOCKET_FILTER,
 152         BPF_PROG_TYPE_KPROBE,
 153         BPF_PROG_TYPE_SCHED_CLS,
 154         BPF_PROG_TYPE_SCHED_ACT,
 155         BPF_PROG_TYPE_TRACEPOINT,
 156         BPF_PROG_TYPE_XDP,
 157         BPF_PROG_TYPE_PERF_EVENT,
 158         BPF_PROG_TYPE_CGROUP_SKB,
 159         BPF_PROG_TYPE_CGROUP_SOCK,
 160         BPF_PROG_TYPE_LWT_IN,
 161         BPF_PROG_TYPE_LWT_OUT,
 162         BPF_PROG_TYPE_LWT_XMIT,
 163         BPF_PROG_TYPE_SOCK_OPS,
 164         BPF_PROG_TYPE_SK_SKB,
 165         BPF_PROG_TYPE_CGROUP_DEVICE,
 166         BPF_PROG_TYPE_SK_MSG,
 167         BPF_PROG_TYPE_RAW_TRACEPOINT,
 168         BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
 169         BPF_PROG_TYPE_LWT_SEG6LOCAL,
 170         BPF_PROG_TYPE_LIRC_MODE2,
 171         BPF_PROG_TYPE_SK_REUSEPORT,
 172         BPF_PROG_TYPE_FLOW_DISSECTOR,
 173         BPF_PROG_TYPE_CGROUP_SYSCTL,
 174         BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE,
 175         BPF_PROG_TYPE_CGROUP_SOCKOPT,
 176 };
 177 
 178 enum bpf_attach_type {
 179         BPF_CGROUP_INET_INGRESS,
 180         BPF_CGROUP_INET_EGRESS,
 181         BPF_CGROUP_INET_SOCK_CREATE,
 182         BPF_CGROUP_SOCK_OPS,
 183         BPF_SK_SKB_STREAM_PARSER,
 184         BPF_SK_SKB_STREAM_VERDICT,
 185         BPF_CGROUP_DEVICE,
 186         BPF_SK_MSG_VERDICT,
 187         BPF_CGROUP_INET4_BIND,
 188         BPF_CGROUP_INET6_BIND,
 189         BPF_CGROUP_INET4_CONNECT,
 190         BPF_CGROUP_INET6_CONNECT,
 191         BPF_CGROUP_INET4_POST_BIND,
 192         BPF_CGROUP_INET6_POST_BIND,
 193         BPF_CGROUP_UDP4_SENDMSG,
 194         BPF_CGROUP_UDP6_SENDMSG,
 195         BPF_LIRC_MODE2,
 196         BPF_FLOW_DISSECTOR,
 197         BPF_CGROUP_SYSCTL,
 198         BPF_CGROUP_UDP4_RECVMSG,
 199         BPF_CGROUP_UDP6_RECVMSG,
 200         BPF_CGROUP_GETSOCKOPT,
 201         BPF_CGROUP_SETSOCKOPT,
 202         __MAX_BPF_ATTACH_TYPE
 203 };
 204 
 205 #define MAX_BPF_ATTACH_TYPE __MAX_BPF_ATTACH_TYPE
 206 
 207 /* cgroup-bpf attach flags used in BPF_PROG_ATTACH command
 208  *
 209  * NONE(default): No further bpf programs allowed in the subtree.
 210  *
 211  * BPF_F_ALLOW_OVERRIDE: If a sub-cgroup installs some bpf program,
 212  * the program in this cgroup yields to sub-cgroup program.
 213  *
 214  * BPF_F_ALLOW_MULTI: If a sub-cgroup installs some bpf program,
 215  * that cgroup program gets run in addition to the program in this cgroup.
 216  *
 217  * Only one program is allowed to be attached to a cgroup with
 218  * NONE or BPF_F_ALLOW_OVERRIDE flag.
 219  * Attaching another program on top of NONE or BPF_F_ALLOW_OVERRIDE will
 220  * release old program and attach the new one. Attach flags has to match.
 221  *
 222  * Multiple programs are allowed to be attached to a cgroup with
 223  * BPF_F_ALLOW_MULTI flag. They are executed in FIFO order
 224  * (those that were attached first, run first)
 225  * The programs of sub-cgroup are executed first, then programs of
 226  * this cgroup and then programs of parent cgroup.
 227  * When children program makes decision (like picking TCP CA or sock bind)
 228  * parent program has a chance to override it.
 229  *
 230  * A cgroup with MULTI or OVERRIDE flag allows any attach flags in sub-cgroups.
 231  * A cgroup with NONE doesn't allow any programs in sub-cgroups.
 232  * Ex1:
 233  * cgrp1 (MULTI progs A, B) ->
 234  *    cgrp2 (OVERRIDE prog C) ->
 235  *      cgrp3 (MULTI prog D) ->
 236  *        cgrp4 (OVERRIDE prog E) ->
 237  *          cgrp5 (NONE prog F)
 238  * the event in cgrp5 triggers execution of F,D,A,B in that order.
 239  * if prog F is detached, the execution is E,D,A,B
 240  * if prog F and D are detached, the execution is E,A,B
 241  * if prog F, E and D are detached, the execution is C,A,B
 242  *
 243  * All eligible programs are executed regardless of return code from
 244  * earlier programs.
 245  */
 246 #define BPF_F_ALLOW_OVERRIDE    (1U << 0)
 247 #define BPF_F_ALLOW_MULTI       (1U << 1)
 248 
 249 /* If BPF_F_STRICT_ALIGNMENT is used in BPF_PROG_LOAD command, the
 250  * verifier will perform strict alignment checking as if the kernel
 251  * has been built with CONFIG_EFFICIENT_UNALIGNED_ACCESS not set,
 252  * and NET_IP_ALIGN defined to 2.
 253  */
 254 #define BPF_F_STRICT_ALIGNMENT  (1U << 0)
 255 
 256 /* If BPF_F_ANY_ALIGNMENT is used in BPF_PROF_LOAD command, the
 257  * verifier will allow any alignment whatsoever.  On platforms
 258  * with strict alignment requirements for loads ands stores (such
 259  * as sparc and mips) the verifier validates that all loads and
 260  * stores provably follow this requirement.  This flag turns that
 261  * checking and enforcement off.
 262  *
 263  * It is mostly used for testing when we want to validate the
 264  * context and memory access aspects of the verifier, but because
 265  * of an unaligned access the alignment check would trigger before
 266  * the one we are interested in.
 267  */
 268 #define BPF_F_ANY_ALIGNMENT     (1U << 1)
 269 
 270 /* BPF_F_TEST_RND_HI32 is used in BPF_PROG_LOAD command for testing purpose.
 271  * Verifier does sub-register def/use analysis and identifies instructions whose
 272  * def only matters for low 32-bit, high 32-bit is never referenced later
 273  * through implicit zero extension. Therefore verifier notifies JIT back-ends
 274  * that it is safe to ignore clearing high 32-bit for these instructions. This
 275  * saves some back-ends a lot of code-gen. However such optimization is not
 276  * necessary on some arches, for example x86_64, arm64 etc, whose JIT back-ends
 277  * hence hasn't used verifier's analysis result. But, we really want to have a
 278  * way to be able to verify the correctness of the described optimization on
 279  * x86_64 on which testsuites are frequently exercised.
 280  *
 281  * So, this flag is introduced. Once it is set, verifier will randomize high
 282  * 32-bit for those instructions who has been identified as safe to ignore them.
 283  * Then, if verifier is not doing correct analysis, such randomization will
 284  * regress tests to expose bugs.
 285  */
 286 #define BPF_F_TEST_RND_HI32     (1U << 2)
 287 
 288 /* The verifier internal test flag. Behavior is undefined */
 289 #define BPF_F_TEST_STATE_FREQ   (1U << 3)
 290 
 291 /* When BPF ldimm64's insn[0].src_reg != 0 then this can have
 292  * two extensions:
 293  *
 294  * insn[0].src_reg:  BPF_PSEUDO_MAP_FD   BPF_PSEUDO_MAP_VALUE
 295  * insn[0].imm:      map fd              map fd
 296  * insn[1].imm:      0                   offset into value
 297  * insn[0].off:      0                   0
 298  * insn[1].off:      0                   0
 299  * ldimm64 rewrite:  address of map      address of map[0]+offset
 300  * verifier type:    CONST_PTR_TO_MAP    PTR_TO_MAP_VALUE
 301  */
 302 #define BPF_PSEUDO_MAP_FD       1
 303 #define BPF_PSEUDO_MAP_VALUE    2
 304 
 305 /* when bpf_call->src_reg == BPF_PSEUDO_CALL, bpf_call->imm == pc-relative
 306  * offset to another bpf function
 307  */
 308 #define BPF_PSEUDO_CALL         1
 309 
 310 /* flags for BPF_MAP_UPDATE_ELEM command */
 311 #define BPF_ANY         0 /* create new element or update existing */
 312 #define BPF_NOEXIST     1 /* create new element if it didn't exist */
 313 #define BPF_EXIST       2 /* update existing element */
 314 #define BPF_F_LOCK      4 /* spin_lock-ed map_lookup/map_update */
 315 
 316 /* flags for BPF_MAP_CREATE command */
 317 #define BPF_F_NO_PREALLOC       (1U << 0)
 318 /* Instead of having one common LRU list in the
 319  * BPF_MAP_TYPE_LRU_[PERCPU_]HASH map, use a percpu LRU list
 320  * which can scale and perform better.
 321  * Note, the LRU nodes (including free nodes) cannot be moved
 322  * across different LRU lists.
 323  */
 324 #define BPF_F_NO_COMMON_LRU     (1U << 1)
 325 /* Specify numa node during map creation */
 326 #define BPF_F_NUMA_NODE         (1U << 2)
 327 
 328 #define BPF_OBJ_NAME_LEN 16U
 329 
 330 /* Flags for accessing BPF object from syscall side. */
 331 #define BPF_F_RDONLY            (1U << 3)
 332 #define BPF_F_WRONLY            (1U << 4)
 333 
 334 /* Flag for stack_map, store build_id+offset instead of pointer */
 335 #define BPF_F_STACK_BUILD_ID    (1U << 5)
 336 
 337 /* Zero-initialize hash function seed. This should only be used for testing. */
 338 #define BPF_F_ZERO_SEED         (1U << 6)
 339 
 340 /* Flags for accessing BPF object from program side. */
 341 #define BPF_F_RDONLY_PROG       (1U << 7)
 342 #define BPF_F_WRONLY_PROG       (1U << 8)
 343 
 344 /* Clone map from listener for newly accepted socket */
 345 #define BPF_F_CLONE             (1U << 9)
 346 
 347 /* flags for BPF_PROG_QUERY */
 348 #define BPF_F_QUERY_EFFECTIVE   (1U << 0)
 349 
 350 enum bpf_stack_build_id_status {
 351         /* user space need an empty entry to identify end of a trace */
 352         BPF_STACK_BUILD_ID_EMPTY = 0,
 353         /* with valid build_id and offset */
 354         BPF_STACK_BUILD_ID_VALID = 1,
 355         /* couldn't get build_id, fallback to ip */
 356         BPF_STACK_BUILD_ID_IP = 2,
 357 };
 358 
 359 #define BPF_BUILD_ID_SIZE 20
 360 struct bpf_stack_build_id {
 361         __s32           status;
 362         unsigned char   build_id[BPF_BUILD_ID_SIZE];
 363         union {
 364                 __u64   offset;
 365                 __u64   ip;
 366         };
 367 };
 368 
 369 union bpf_attr {
 370         struct { /* anonymous struct used by BPF_MAP_CREATE command */
 371                 __u32   map_type;       /* one of enum bpf_map_type */
 372                 __u32   key_size;       /* size of key in bytes */
 373                 __u32   value_size;     /* size of value in bytes */
 374                 __u32   max_entries;    /* max number of entries in a map */
 375                 __u32   map_flags;      /* BPF_MAP_CREATE related
 376                                          * flags defined above.
 377                                          */
 378                 __u32   inner_map_fd;   /* fd pointing to the inner map */
 379                 __u32   numa_node;      /* numa node (effective only if
 380                                          * BPF_F_NUMA_NODE is set).
 381                                          */
 382                 char    map_name[BPF_OBJ_NAME_LEN];
 383                 __u32   map_ifindex;    /* ifindex of netdev to create on */
 384                 __u32   btf_fd;         /* fd pointing to a BTF type data */
 385                 __u32   btf_key_type_id;        /* BTF type_id of the key */
 386                 __u32   btf_value_type_id;      /* BTF type_id of the value */
 387         };
 388 
 389         struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
 390                 __u32           map_fd;
 391                 __aligned_u64   key;
 392                 union {
 393                         __aligned_u64 value;
 394                         __aligned_u64 next_key;
 395                 };
 396                 __u64           flags;
 397         };
 398 
 399         struct { /* anonymous struct used by BPF_PROG_LOAD command */
 400                 __u32           prog_type;      /* one of enum bpf_prog_type */
 401                 __u32           insn_cnt;
 402                 __aligned_u64   insns;
 403                 __aligned_u64   license;
 404                 __u32           log_level;      /* verbosity level of verifier */
 405                 __u32           log_size;       /* size of user buffer */
 406                 __aligned_u64   log_buf;        /* user supplied buffer */
 407                 __u32           kern_version;   /* not used */
 408                 __u32           prog_flags;
 409                 char            prog_name[BPF_OBJ_NAME_LEN];
 410                 __u32           prog_ifindex;   /* ifindex of netdev to prep for */
 411                 /* For some prog types expected attach type must be known at
 412                  * load time to verify attach type specific parts of prog
 413                  * (context accesses, allowed helpers, etc).
 414                  */
 415                 __u32           expected_attach_type;
 416                 __u32           prog_btf_fd;    /* fd pointing to BTF type data */
 417                 __u32           func_info_rec_size;     /* userspace bpf_func_info size */
 418                 __aligned_u64   func_info;      /* func info */
 419                 __u32           func_info_cnt;  /* number of bpf_func_info records */
 420                 __u32           line_info_rec_size;     /* userspace bpf_line_info size */
 421                 __aligned_u64   line_info;      /* line info */
 422                 __u32           line_info_cnt;  /* number of bpf_line_info records */
 423         };
 424 
 425         struct { /* anonymous struct used by BPF_OBJ_* commands */
 426                 __aligned_u64   pathname;
 427                 __u32           bpf_fd;
 428                 __u32           file_flags;
 429         };
 430 
 431         struct { /* anonymous struct used by BPF_PROG_ATTACH/DETACH commands */
 432                 __u32           target_fd;      /* container object to attach to */
 433                 __u32           attach_bpf_fd;  /* eBPF program to attach */
 434                 __u32           attach_type;
 435                 __u32           attach_flags;
 436         };
 437 
 438         struct { /* anonymous struct used by BPF_PROG_TEST_RUN command */
 439                 __u32           prog_fd;
 440                 __u32           retval;
 441                 __u32           data_size_in;   /* input: len of data_in */
 442                 __u32           data_size_out;  /* input/output: len of data_out
 443                                                  *   returns ENOSPC if data_out
 444                                                  *   is too small.
 445                                                  */
 446                 __aligned_u64   data_in;
 447                 __aligned_u64   data_out;
 448                 __u32           repeat;
 449                 __u32           duration;
 450                 __u32           ctx_size_in;    /* input: len of ctx_in */
 451                 __u32           ctx_size_out;   /* input/output: len of ctx_out
 452                                                  *   returns ENOSPC if ctx_out
 453                                                  *   is too small.
 454                                                  */
 455                 __aligned_u64   ctx_in;
 456                 __aligned_u64   ctx_out;
 457         } test;
 458 
 459         struct { /* anonymous struct used by BPF_*_GET_*_ID */
 460                 union {
 461                         __u32           start_id;
 462                         __u32           prog_id;
 463                         __u32           map_id;
 464                         __u32           btf_id;
 465                 };
 466                 __u32           next_id;
 467                 __u32           open_flags;
 468         };
 469 
 470         struct { /* anonymous struct used by BPF_OBJ_GET_INFO_BY_FD */
 471                 __u32           bpf_fd;
 472                 __u32           info_len;
 473                 __aligned_u64   info;
 474         } info;
 475 
 476         struct { /* anonymous struct used by BPF_PROG_QUERY command */
 477                 __u32           target_fd;      /* container object to query */
 478                 __u32           attach_type;
 479                 __u32           query_flags;
 480                 __u32           attach_flags;
 481                 __aligned_u64   prog_ids;
 482                 __u32           prog_cnt;
 483         } query;
 484 
 485         struct {
 486                 __u64 name;
 487                 __u32 prog_fd;
 488         } raw_tracepoint;
 489 
 490         struct { /* anonymous struct for BPF_BTF_LOAD */
 491                 __aligned_u64   btf;
 492                 __aligned_u64   btf_log_buf;
 493                 __u32           btf_size;
 494                 __u32           btf_log_size;
 495                 __u32           btf_log_level;
 496         };
 497 
 498         struct {
 499                 __u32           pid;            /* input: pid */
 500                 __u32           fd;             /* input: fd */
 501                 __u32           flags;          /* input: flags */
 502                 __u32           buf_len;        /* input/output: buf len */
 503                 __aligned_u64   buf;            /* input/output:
 504                                                  *   tp_name for tracepoint
 505                                                  *   symbol for kprobe
 506                                                  *   filename for uprobe
 507                                                  */
 508                 __u32           prog_id;        /* output: prod_id */
 509                 __u32           fd_type;        /* output: BPF_FD_TYPE_* */
 510                 __u64           probe_offset;   /* output: probe_offset */
 511                 __u64           probe_addr;     /* output: probe_addr */
 512         } task_fd_query;
 513 } __attribute__((aligned(8)));
 514 
 515 /* The description below is an attempt at providing documentation to eBPF
 516  * developers about the multiple available eBPF helper functions. It can be
 517  * parsed and used to produce a manual page. The workflow is the following,
 518  * and requires the rst2man utility:
 519  *
 520  *     $ ./scripts/bpf_helpers_doc.py \
 521  *             --filename include/uapi/linux/bpf.h > /tmp/bpf-helpers.rst
 522  *     $ rst2man /tmp/bpf-helpers.rst > /tmp/bpf-helpers.7
 523  *     $ man /tmp/bpf-helpers.7
 524  *
 525  * Note that in order to produce this external documentation, some RST
 526  * formatting is used in the descriptions to get "bold" and "italics" in
 527  * manual pages. Also note that the few trailing white spaces are
 528  * intentional, removing them would break paragraphs for rst2man.
 529  *
 530  * Start of BPF helper function descriptions:
 531  *
 532  * void *bpf_map_lookup_elem(struct bpf_map *map, const void *key)
 533  *      Description
 534  *              Perform a lookup in *map* for an entry associated to *key*.
 535  *      Return
 536  *              Map value associated to *key*, or **NULL** if no entry was
 537  *              found.
 538  *
 539  * int bpf_map_update_elem(struct bpf_map *map, const void *key, const void *value, u64 flags)
 540  *      Description
 541  *              Add or update the value of the entry associated to *key* in
 542  *              *map* with *value*. *flags* is one of:
 543  *
 544  *              **BPF_NOEXIST**
 545  *                      The entry for *key* must not exist in the map.
 546  *              **BPF_EXIST**
 547  *                      The entry for *key* must already exist in the map.
 548  *              **BPF_ANY**
 549  *                      No condition on the existence of the entry for *key*.
 550  *
 551  *              Flag value **BPF_NOEXIST** cannot be used for maps of types
 552  *              **BPF_MAP_TYPE_ARRAY** or **BPF_MAP_TYPE_PERCPU_ARRAY**  (all
 553  *              elements always exist), the helper would return an error.
 554  *      Return
 555  *              0 on success, or a negative error in case of failure.
 556  *
 557  * int bpf_map_delete_elem(struct bpf_map *map, const void *key)
 558  *      Description
 559  *              Delete entry with *key* from *map*.
 560  *      Return
 561  *              0 on success, or a negative error in case of failure.
 562  *
 563  * int bpf_probe_read(void *dst, u32 size, const void *src)
 564  *      Description
 565  *              For tracing programs, safely attempt to read *size* bytes from
 566  *              address *src* and store the data in *dst*.
 567  *      Return
 568  *              0 on success, or a negative error in case of failure.
 569  *
 570  * u64 bpf_ktime_get_ns(void)
 571  *      Description
 572  *              Return the time elapsed since system boot, in nanoseconds.
 573  *      Return
 574  *              Current *ktime*.
 575  *
 576  * int bpf_trace_printk(const char *fmt, u32 fmt_size, ...)
 577  *      Description
 578  *              This helper is a "printk()-like" facility for debugging. It
 579  *              prints a message defined by format *fmt* (of size *fmt_size*)
 580  *              to file *\/sys/kernel/debug/tracing/trace* from DebugFS, if
 581  *              available. It can take up to three additional **u64**
 582  *              arguments (as an eBPF helpers, the total number of arguments is
 583  *              limited to five).
 584  *
 585  *              Each time the helper is called, it appends a line to the trace.
 586  *              Lines are discarded while *\/sys/kernel/debug/tracing/trace* is
 587  *              open, use *\/sys/kernel/debug/tracing/trace_pipe* to avoid this.
 588  *              The format of the trace is customizable, and the exact output
 589  *              one will get depends on the options set in
 590  *              *\/sys/kernel/debug/tracing/trace_options* (see also the
 591  *              *README* file under the same directory). However, it usually
 592  *              defaults to something like:
 593  *
 594  *              ::
 595  *
 596  *                      telnet-470   [001] .N.. 419421.045894: 0x00000001: <formatted msg>
 597  *
 598  *              In the above:
 599  *
 600  *                      * ``telnet`` is the name of the current task.
 601  *                      * ``470`` is the PID of the current task.
 602  *                      * ``001`` is the CPU number on which the task is
 603  *                        running.
 604  *                      * In ``.N..``, each character refers to a set of
 605  *                        options (whether irqs are enabled, scheduling
 606  *                        options, whether hard/softirqs are running, level of
 607  *                        preempt_disabled respectively). **N** means that
 608  *                        **TIF_NEED_RESCHED** and **PREEMPT_NEED_RESCHED**
 609  *                        are set.
 610  *                      * ``419421.045894`` is a timestamp.
 611  *                      * ``0x00000001`` is a fake value used by BPF for the
 612  *                        instruction pointer register.
 613  *                      * ``<formatted msg>`` is the message formatted with
 614  *                        *fmt*.
 615  *
 616  *              The conversion specifiers supported by *fmt* are similar, but
 617  *              more limited than for printk(). They are **%d**, **%i**,
 618  *              **%u**, **%x**, **%ld**, **%li**, **%lu**, **%lx**, **%lld**,
 619  *              **%lli**, **%llu**, **%llx**, **%p**, **%s**. No modifier (size
 620  *              of field, padding with zeroes, etc.) is available, and the
 621  *              helper will return **-EINVAL** (but print nothing) if it
 622  *              encounters an unknown specifier.
 623  *
 624  *              Also, note that **bpf_trace_printk**\ () is slow, and should
 625  *              only be used for debugging purposes. For this reason, a notice
 626  *              bloc (spanning several lines) is printed to kernel logs and
 627  *              states that the helper should not be used "for production use"
 628  *              the first time this helper is used (or more precisely, when
 629  *              **trace_printk**\ () buffers are allocated). For passing values
 630  *              to user space, perf events should be preferred.
 631  *      Return
 632  *              The number of bytes written to the buffer, or a negative error
 633  *              in case of failure.
 634  *
 635  * u32 bpf_get_prandom_u32(void)
 636  *      Description
 637  *              Get a pseudo-random number.
 638  *
 639  *              From a security point of view, this helper uses its own
 640  *              pseudo-random internal state, and cannot be used to infer the
 641  *              seed of other random functions in the kernel. However, it is
 642  *              essential to note that the generator used by the helper is not
 643  *              cryptographically secure.
 644  *      Return
 645  *              A random 32-bit unsigned value.
 646  *
 647  * u32 bpf_get_smp_processor_id(void)
 648  *      Description
 649  *              Get the SMP (symmetric multiprocessing) processor id. Note that
 650  *              all programs run with preemption disabled, which means that the
 651  *              SMP processor id is stable during all the execution of the
 652  *              program.
 653  *      Return
 654  *              The SMP id of the processor running the program.
 655  *
 656  * int bpf_skb_store_bytes(struct sk_buff *skb, u32 offset, const void *from, u32 len, u64 flags)
 657  *      Description
 658  *              Store *len* bytes from address *from* into the packet
 659  *              associated to *skb*, at *offset*. *flags* are a combination of
 660  *              **BPF_F_RECOMPUTE_CSUM** (automatically recompute the
 661  *              checksum for the packet after storing the bytes) and
 662  *              **BPF_F_INVALIDATE_HASH** (set *skb*\ **->hash**, *skb*\
 663  *              **->swhash** and *skb*\ **->l4hash** to 0).
 664  *
 665  *              A call to this helper is susceptible to change the underlying
 666  *              packet buffer. Therefore, at load time, all checks on pointers
 667  *              previously done by the verifier are invalidated and must be
 668  *              performed again, if the helper is used in combination with
 669  *              direct packet access.
 670  *      Return
 671  *              0 on success, or a negative error in case of failure.
 672  *
 673  * int bpf_l3_csum_replace(struct sk_buff *skb, u32 offset, u64 from, u64 to, u64 size)
 674  *      Description
 675  *              Recompute the layer 3 (e.g. IP) checksum for the packet
 676  *              associated to *skb*. Computation is incremental, so the helper
 677  *              must know the former value of the header field that was
 678  *              modified (*from*), the new value of this field (*to*), and the
 679  *              number of bytes (2 or 4) for this field, stored in *size*.
 680  *              Alternatively, it is possible to store the difference between
 681  *              the previous and the new values of the header field in *to*, by
 682  *              setting *from* and *size* to 0. For both methods, *offset*
 683  *              indicates the location of the IP checksum within the packet.
 684  *
 685  *              This helper works in combination with **bpf_csum_diff**\ (),
 686  *              which does not update the checksum in-place, but offers more
 687  *              flexibility and can handle sizes larger than 2 or 4 for the
 688  *              checksum to update.
 689  *
 690  *              A call to this helper is susceptible to change the underlying
 691  *              packet buffer. Therefore, at load time, all checks on pointers
 692  *              previously done by the verifier are invalidated and must be
 693  *              performed again, if the helper is used in combination with
 694  *              direct packet access.
 695  *      Return
 696  *              0 on success, or a negative error in case of failure.
 697  *
 698  * int bpf_l4_csum_replace(struct sk_buff *skb, u32 offset, u64 from, u64 to, u64 flags)
 699  *      Description
 700  *              Recompute the layer 4 (e.g. TCP, UDP or ICMP) checksum for the
 701  *              packet associated to *skb*. Computation is incremental, so the
 702  *              helper must know the former value of the header field that was
 703  *              modified (*from*), the new value of this field (*to*), and the
 704  *              number of bytes (2 or 4) for this field, stored on the lowest
 705  *              four bits of *flags*. Alternatively, it is possible to store
 706  *              the difference between the previous and the new values of the
 707  *              header field in *to*, by setting *from* and the four lowest
 708  *              bits of *flags* to 0. For both methods, *offset* indicates the
 709  *              location of the IP checksum within the packet. In addition to
 710  *              the size of the field, *flags* can be added (bitwise OR) actual
 711  *              flags. With **BPF_F_MARK_MANGLED_0**, a null checksum is left
 712  *              untouched (unless **BPF_F_MARK_ENFORCE** is added as well), and
 713  *              for updates resulting in a null checksum the value is set to
 714  *              **CSUM_MANGLED_0** instead. Flag **BPF_F_PSEUDO_HDR** indicates
 715  *              the checksum is to be computed against a pseudo-header.
 716  *
 717  *              This helper works in combination with **bpf_csum_diff**\ (),
 718  *              which does not update the checksum in-place, but offers more
 719  *              flexibility and can handle sizes larger than 2 or 4 for the
 720  *              checksum to update.
 721  *
 722  *              A call to this helper is susceptible to change the underlying
 723  *              packet buffer. Therefore, at load time, all checks on pointers
 724  *              previously done by the verifier are invalidated and must be
 725  *              performed again, if the helper is used in combination with
 726  *              direct packet access.
 727  *      Return
 728  *              0 on success, or a negative error in case of failure.
 729  *
 730  * int bpf_tail_call(void *ctx, struct bpf_map *prog_array_map, u32 index)
 731  *      Description
 732  *              This special helper is used to trigger a "tail call", or in
 733  *              other words, to jump into another eBPF program. The same stack
 734  *              frame is used (but values on stack and in registers for the
 735  *              caller are not accessible to the callee). This mechanism allows
 736  *              for program chaining, either for raising the maximum number of
 737  *              available eBPF instructions, or to execute given programs in
 738  *              conditional blocks. For security reasons, there is an upper
 739  *              limit to the number of successive tail calls that can be
 740  *              performed.
 741  *
 742  *              Upon call of this helper, the program attempts to jump into a
 743  *              program referenced at index *index* in *prog_array_map*, a
 744  *              special map of type **BPF_MAP_TYPE_PROG_ARRAY**, and passes
 745  *              *ctx*, a pointer to the context.
 746  *
 747  *              If the call succeeds, the kernel immediately runs the first
 748  *              instruction of the new program. This is not a function call,
 749  *              and it never returns to the previous program. If the call
 750  *              fails, then the helper has no effect, and the caller continues
 751  *              to run its subsequent instructions. A call can fail if the
 752  *              destination program for the jump does not exist (i.e. *index*
 753  *              is superior to the number of entries in *prog_array_map*), or
 754  *              if the maximum number of tail calls has been reached for this
 755  *              chain of programs. This limit is defined in the kernel by the
 756  *              macro **MAX_TAIL_CALL_CNT** (not accessible to user space),
 757  *              which is currently set to 32.
 758  *      Return
 759  *              0 on success, or a negative error in case of failure.
 760  *
 761  * int bpf_clone_redirect(struct sk_buff *skb, u32 ifindex, u64 flags)
 762  *      Description
 763  *              Clone and redirect the packet associated to *skb* to another
 764  *              net device of index *ifindex*. Both ingress and egress
 765  *              interfaces can be used for redirection. The **BPF_F_INGRESS**
 766  *              value in *flags* is used to make the distinction (ingress path
 767  *              is selected if the flag is present, egress path otherwise).
 768  *              This is the only flag supported for now.
 769  *
 770  *              In comparison with **bpf_redirect**\ () helper,
 771  *              **bpf_clone_redirect**\ () has the associated cost of
 772  *              duplicating the packet buffer, but this can be executed out of
 773  *              the eBPF program. Conversely, **bpf_redirect**\ () is more
 774  *              efficient, but it is handled through an action code where the
 775  *              redirection happens only after the eBPF program has returned.
 776  *
 777  *              A call to this helper is susceptible to change the underlying
 778  *              packet buffer. Therefore, at load time, all checks on pointers
 779  *              previously done by the verifier are invalidated and must be
 780  *              performed again, if the helper is used in combination with
 781  *              direct packet access.
 782  *      Return
 783  *              0 on success, or a negative error in case of failure.
 784  *
 785  * u64 bpf_get_current_pid_tgid(void)
 786  *      Return
 787  *              A 64-bit integer containing the current tgid and pid, and
 788  *              created as such:
 789  *              *current_task*\ **->tgid << 32 \|**
 790  *              *current_task*\ **->pid**.
 791  *
 792  * u64 bpf_get_current_uid_gid(void)
 793  *      Return
 794  *              A 64-bit integer containing the current GID and UID, and
 795  *              created as such: *current_gid* **<< 32 \|** *current_uid*.
 796  *
 797  * int bpf_get_current_comm(char *buf, u32 size_of_buf)
 798  *      Description
 799  *              Copy the **comm** attribute of the current task into *buf* of
 800  *              *size_of_buf*. The **comm** attribute contains the name of
 801  *              the executable (excluding the path) for the current task. The
 802  *              *size_of_buf* must be strictly positive. On success, the
 803  *              helper makes sure that the *buf* is NUL-terminated. On failure,
 804  *              it is filled with zeroes.
 805  *      Return
 806  *              0 on success, or a negative error in case of failure.
 807  *
 808  * u32 bpf_get_cgroup_classid(struct sk_buff *skb)
 809  *      Description
 810  *              Retrieve the classid for the current task, i.e. for the net_cls
 811  *              cgroup to which *skb* belongs.
 812  *
 813  *              This helper can be used on TC egress path, but not on ingress.
 814  *
 815  *              The net_cls cgroup provides an interface to tag network packets
 816  *              based on a user-provided identifier for all traffic coming from
 817  *              the tasks belonging to the related cgroup. See also the related
 818  *              kernel documentation, available from the Linux sources in file
 819  *              *Documentation/admin-guide/cgroup-v1/net_cls.rst*.
 820  *
 821  *              The Linux kernel has two versions for cgroups: there are
 822  *              cgroups v1 and cgroups v2. Both are available to users, who can
 823  *              use a mixture of them, but note that the net_cls cgroup is for
 824  *              cgroup v1 only. This makes it incompatible with BPF programs
 825  *              run on cgroups, which is a cgroup-v2-only feature (a socket can
 826  *              only hold data for one version of cgroups at a time).
 827  *
 828  *              This helper is only available is the kernel was compiled with
 829  *              the **CONFIG_CGROUP_NET_CLASSID** configuration option set to
 830  *              "**y**" or to "**m**".
 831  *      Return
 832  *              The classid, or 0 for the default unconfigured classid.
 833  *
 834  * int bpf_skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
 835  *      Description
 836  *              Push a *vlan_tci* (VLAN tag control information) of protocol
 837  *              *vlan_proto* to the packet associated to *skb*, then update
 838  *              the checksum. Note that if *vlan_proto* is different from
 839  *              **ETH_P_8021Q** and **ETH_P_8021AD**, it is considered to
 840  *              be **ETH_P_8021Q**.
 841  *
 842  *              A call to this helper is susceptible to change the underlying
 843  *              packet buffer. Therefore, at load time, all checks on pointers
 844  *              previously done by the verifier are invalidated and must be
 845  *              performed again, if the helper is used in combination with
 846  *              direct packet access.
 847  *      Return
 848  *              0 on success, or a negative error in case of failure.
 849  *
 850  * int bpf_skb_vlan_pop(struct sk_buff *skb)
 851  *      Description
 852  *              Pop a VLAN header from the packet associated to *skb*.
 853  *
 854  *              A call to this helper is susceptible to change the underlying
 855  *              packet buffer. Therefore, at load time, all checks on pointers
 856  *              previously done by the verifier are invalidated and must be
 857  *              performed again, if the helper is used in combination with
 858  *              direct packet access.
 859  *      Return
 860  *              0 on success, or a negative error in case of failure.
 861  *
 862  * int bpf_skb_get_tunnel_key(struct sk_buff *skb, struct bpf_tunnel_key *key, u32 size, u64 flags)
 863  *      Description
 864  *              Get tunnel metadata. This helper takes a pointer *key* to an
 865  *              empty **struct bpf_tunnel_key** of **size**, that will be
 866  *              filled with tunnel metadata for the packet associated to *skb*.
 867  *              The *flags* can be set to **BPF_F_TUNINFO_IPV6**, which
 868  *              indicates that the tunnel is based on IPv6 protocol instead of
 869  *              IPv4.
 870  *
 871  *              The **struct bpf_tunnel_key** is an object that generalizes the
 872  *              principal parameters used by various tunneling protocols into a
 873  *              single struct. This way, it can be used to easily make a
 874  *              decision based on the contents of the encapsulation header,
 875  *              "summarized" in this struct. In particular, it holds the IP
 876  *              address of the remote end (IPv4 or IPv6, depending on the case)
 877  *              in *key*\ **->remote_ipv4** or *key*\ **->remote_ipv6**. Also,
 878  *              this struct exposes the *key*\ **->tunnel_id**, which is
 879  *              generally mapped to a VNI (Virtual Network Identifier), making
 880  *              it programmable together with the **bpf_skb_set_tunnel_key**\
 881  *              () helper.
 882  *
 883  *              Let's imagine that the following code is part of a program
 884  *              attached to the TC ingress interface, on one end of a GRE
 885  *              tunnel, and is supposed to filter out all messages coming from
 886  *              remote ends with IPv4 address other than 10.0.0.1:
 887  *
 888  *              ::
 889  *
 890  *                      int ret;
 891  *                      struct bpf_tunnel_key key = {};
 892  *                      
 893  *                      ret = bpf_skb_get_tunnel_key(skb, &key, sizeof(key), 0);
 894  *                      if (ret < 0)
 895  *                              return TC_ACT_SHOT;     // drop packet
 896  *                      
 897  *                      if (key.remote_ipv4 != 0x0a000001)
 898  *                              return TC_ACT_SHOT;     // drop packet
 899  *                      
 900  *                      return TC_ACT_OK;               // accept packet
 901  *
 902  *              This interface can also be used with all encapsulation devices
 903  *              that can operate in "collect metadata" mode: instead of having
 904  *              one network device per specific configuration, the "collect
 905  *              metadata" mode only requires a single device where the
 906  *              configuration can be extracted from this helper.
 907  *
 908  *              This can be used together with various tunnels such as VXLan,
 909  *              Geneve, GRE or IP in IP (IPIP).
 910  *      Return
 911  *              0 on success, or a negative error in case of failure.
 912  *
 913  * int bpf_skb_set_tunnel_key(struct sk_buff *skb, struct bpf_tunnel_key *key, u32 size, u64 flags)
 914  *      Description
 915  *              Populate tunnel metadata for packet associated to *skb.* The
 916  *              tunnel metadata is set to the contents of *key*, of *size*. The
 917  *              *flags* can be set to a combination of the following values:
 918  *
 919  *              **BPF_F_TUNINFO_IPV6**
 920  *                      Indicate that the tunnel is based on IPv6 protocol
 921  *                      instead of IPv4.
 922  *              **BPF_F_ZERO_CSUM_TX**
 923  *                      For IPv4 packets, add a flag to tunnel metadata
 924  *                      indicating that checksum computation should be skipped
 925  *                      and checksum set to zeroes.
 926  *              **BPF_F_DONT_FRAGMENT**
 927  *                      Add a flag to tunnel metadata indicating that the
 928  *                      packet should not be fragmented.
 929  *              **BPF_F_SEQ_NUMBER**
 930  *                      Add a flag to tunnel metadata indicating that a
 931  *                      sequence number should be added to tunnel header before
 932  *                      sending the packet. This flag was added for GRE
 933  *                      encapsulation, but might be used with other protocols
 934  *                      as well in the future.
 935  *
 936  *              Here is a typical usage on the transmit path:
 937  *
 938  *              ::
 939  *
 940  *                      struct bpf_tunnel_key key;
 941  *                           populate key ...
 942  *                      bpf_skb_set_tunnel_key(skb, &key, sizeof(key), 0);
 943  *                      bpf_clone_redirect(skb, vxlan_dev_ifindex, 0);
 944  *
 945  *              See also the description of the **bpf_skb_get_tunnel_key**\ ()
 946  *              helper for additional information.
 947  *      Return
 948  *              0 on success, or a negative error in case of failure.
 949  *
 950  * u64 bpf_perf_event_read(struct bpf_map *map, u64 flags)
 951  *      Description
 952  *              Read the value of a perf event counter. This helper relies on a
 953  *              *map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. The nature of
 954  *              the perf event counter is selected when *map* is updated with
 955  *              perf event file descriptors. The *map* is an array whose size
 956  *              is the number of available CPUs, and each cell contains a value
 957  *              relative to one CPU. The value to retrieve is indicated by
 958  *              *flags*, that contains the index of the CPU to look up, masked
 959  *              with **BPF_F_INDEX_MASK**. Alternatively, *flags* can be set to
 960  *              **BPF_F_CURRENT_CPU** to indicate that the value for the
 961  *              current CPU should be retrieved.
 962  *
 963  *              Note that before Linux 4.13, only hardware perf event can be
 964  *              retrieved.
 965  *
 966  *              Also, be aware that the newer helper
 967  *              **bpf_perf_event_read_value**\ () is recommended over
 968  *              **bpf_perf_event_read**\ () in general. The latter has some ABI
 969  *              quirks where error and counter value are used as a return code
 970  *              (which is wrong to do since ranges may overlap). This issue is
 971  *              fixed with **bpf_perf_event_read_value**\ (), which at the same
 972  *              time provides more features over the **bpf_perf_event_read**\
 973  *              () interface. Please refer to the description of
 974  *              **bpf_perf_event_read_value**\ () for details.
 975  *      Return
 976  *              The value of the perf event counter read from the map, or a
 977  *              negative error code in case of failure.
 978  *
 979  * int bpf_redirect(u32 ifindex, u64 flags)
 980  *      Description
 981  *              Redirect the packet to another net device of index *ifindex*.
 982  *              This helper is somewhat similar to **bpf_clone_redirect**\
 983  *              (), except that the packet is not cloned, which provides
 984  *              increased performance.
 985  *
 986  *              Except for XDP, both ingress and egress interfaces can be used
 987  *              for redirection. The **BPF_F_INGRESS** value in *flags* is used
 988  *              to make the distinction (ingress path is selected if the flag
 989  *              is present, egress path otherwise). Currently, XDP only
 990  *              supports redirection to the egress interface, and accepts no
 991  *              flag at all.
 992  *
 993  *              The same effect can be attained with the more generic
 994  *              **bpf_redirect_map**\ (), which requires specific maps to be
 995  *              used but offers better performance.
 996  *      Return
 997  *              For XDP, the helper returns **XDP_REDIRECT** on success or
 998  *              **XDP_ABORTED** on error. For other program types, the values
 999  *              are **TC_ACT_REDIRECT** on success or **TC_ACT_SHOT** on
1000  *              error.
1001  *
1002  * u32 bpf_get_route_realm(struct sk_buff *skb)
1003  *      Description
1004  *              Retrieve the realm or the route, that is to say the
1005  *              **tclassid** field of the destination for the *skb*. The
1006  *              indentifier retrieved is a user-provided tag, similar to the
1007  *              one used with the net_cls cgroup (see description for
1008  *              **bpf_get_cgroup_classid**\ () helper), but here this tag is
1009  *              held by a route (a destination entry), not by a task.
1010  *
1011  *              Retrieving this identifier works with the clsact TC egress hook
1012  *              (see also **tc-bpf(8)**), or alternatively on conventional
1013  *              classful egress qdiscs, but not on TC ingress path. In case of
1014  *              clsact TC egress hook, this has the advantage that, internally,
1015  *              the destination entry has not been dropped yet in the transmit
1016  *              path. Therefore, the destination entry does not need to be
1017  *              artificially held via **netif_keep_dst**\ () for a classful
1018  *              qdisc until the *skb* is freed.
1019  *
1020  *              This helper is available only if the kernel was compiled with
1021  *              **CONFIG_IP_ROUTE_CLASSID** configuration option.
1022  *      Return
1023  *              The realm of the route for the packet associated to *skb*, or 0
1024  *              if none was found.
1025  *
1026  * int bpf_perf_event_output(struct pt_regs *ctx, struct bpf_map *map, u64 flags, void *data, u64 size)
1027  *      Description
1028  *              Write raw *data* blob into a special BPF perf event held by
1029  *              *map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. This perf
1030  *              event must have the following attributes: **PERF_SAMPLE_RAW**
1031  *              as **sample_type**, **PERF_TYPE_SOFTWARE** as **type**, and
1032  *              **PERF_COUNT_SW_BPF_OUTPUT** as **config**.
1033  *
1034  *              The *flags* are used to indicate the index in *map* for which
1035  *              the value must be put, masked with **BPF_F_INDEX_MASK**.
1036  *              Alternatively, *flags* can be set to **BPF_F_CURRENT_CPU**
1037  *              to indicate that the index of the current CPU core should be
1038  *              used.
1039  *
1040  *              The value to write, of *size*, is passed through eBPF stack and
1041  *              pointed by *data*.
1042  *
1043  *              The context of the program *ctx* needs also be passed to the
1044  *              helper.
1045  *
1046  *              On user space, a program willing to read the values needs to
1047  *              call **perf_event_open**\ () on the perf event (either for
1048  *              one or for all CPUs) and to store the file descriptor into the
1049  *              *map*. This must be done before the eBPF program can send data
1050  *              into it. An example is available in file
1051  *              *samples/bpf/trace_output_user.c* in the Linux kernel source
1052  *              tree (the eBPF program counterpart is in
1053  *              *samples/bpf/trace_output_kern.c*).
1054  *
1055  *              **bpf_perf_event_output**\ () achieves better performance
1056  *              than **bpf_trace_printk**\ () for sharing data with user
1057  *              space, and is much better suitable for streaming data from eBPF
1058  *              programs.
1059  *
1060  *              Note that this helper is not restricted to tracing use cases
1061  *              and can be used with programs attached to TC or XDP as well,
1062  *              where it allows for passing data to user space listeners. Data
1063  *              can be:
1064  *
1065  *              * Only custom structs,
1066  *              * Only the packet payload, or
1067  *              * A combination of both.
1068  *      Return
1069  *              0 on success, or a negative error in case of failure.
1070  *
1071  * int bpf_skb_load_bytes(const struct sk_buff *skb, u32 offset, void *to, u32 len)
1072  *      Description
1073  *              This helper was provided as an easy way to load data from a
1074  *              packet. It can be used to load *len* bytes from *offset* from
1075  *              the packet associated to *skb*, into the buffer pointed by
1076  *              *to*.
1077  *
1078  *              Since Linux 4.7, usage of this helper has mostly been replaced
1079  *              by "direct packet access", enabling packet data to be
1080  *              manipulated with *skb*\ **->data** and *skb*\ **->data_end**
1081  *              pointing respectively to the first byte of packet data and to
1082  *              the byte after the last byte of packet data. However, it
1083  *              remains useful if one wishes to read large quantities of data
1084  *              at once from a packet into the eBPF stack.
1085  *      Return
1086  *              0 on success, or a negative error in case of failure.
1087  *
1088  * int bpf_get_stackid(struct pt_regs *ctx, struct bpf_map *map, u64 flags)
1089  *      Description
1090  *              Walk a user or a kernel stack and return its id. To achieve
1091  *              this, the helper needs *ctx*, which is a pointer to the context
1092  *              on which the tracing program is executed, and a pointer to a
1093  *              *map* of type **BPF_MAP_TYPE_STACK_TRACE**.
1094  *
1095  *              The last argument, *flags*, holds the number of stack frames to
1096  *              skip (from 0 to 255), masked with
1097  *              **BPF_F_SKIP_FIELD_MASK**. The next bits can be used to set
1098  *              a combination of the following flags:
1099  *
1100  *              **BPF_F_USER_STACK**
1101  *                      Collect a user space stack instead of a kernel stack.
1102  *              **BPF_F_FAST_STACK_CMP**
1103  *                      Compare stacks by hash only.
1104  *              **BPF_F_REUSE_STACKID**
1105  *                      If two different stacks hash into the same *stackid*,
1106  *                      discard the old one.
1107  *
1108  *              The stack id retrieved is a 32 bit long integer handle which
1109  *              can be further combined with other data (including other stack
1110  *              ids) and used as a key into maps. This can be useful for
1111  *              generating a variety of graphs (such as flame graphs or off-cpu
1112  *              graphs).
1113  *
1114  *              For walking a stack, this helper is an improvement over
1115  *              **bpf_probe_read**\ (), which can be used with unrolled loops
1116  *              but is not efficient and consumes a lot of eBPF instructions.
1117  *              Instead, **bpf_get_stackid**\ () can collect up to
1118  *              **PERF_MAX_STACK_DEPTH** both kernel and user frames. Note that
1119  *              this limit can be controlled with the **sysctl** program, and
1120  *              that it should be manually increased in order to profile long
1121  *              user stacks (such as stacks for Java programs). To do so, use:
1122  *
1123  *              ::
1124  *
1125  *                      # sysctl kernel.perf_event_max_stack=<new value>
1126  *      Return
1127  *              The positive or null stack id on success, or a negative error
1128  *              in case of failure.
1129  *
1130  * s64 bpf_csum_diff(__be32 *from, u32 from_size, __be32 *to, u32 to_size, __wsum seed)
1131  *      Description
1132  *              Compute a checksum difference, from the raw buffer pointed by
1133  *              *from*, of length *from_size* (that must be a multiple of 4),
1134  *              towards the raw buffer pointed by *to*, of size *to_size*
1135  *              (same remark). An optional *seed* can be added to the value
1136  *              (this can be cascaded, the seed may come from a previous call
1137  *              to the helper).
1138  *
1139  *              This is flexible enough to be used in several ways:
1140  *
1141  *              * With *from_size* == 0, *to_size* > 0 and *seed* set to
1142  *                checksum, it can be used when pushing new data.
1143  *              * With *from_size* > 0, *to_size* == 0 and *seed* set to
1144  *                checksum, it can be used when removing data from a packet.
1145  *              * With *from_size* > 0, *to_size* > 0 and *seed* set to 0, it
1146  *                can be used to compute a diff. Note that *from_size* and
1147  *                *to_size* do not need to be equal.
1148  *
1149  *              This helper can be used in combination with
1150  *              **bpf_l3_csum_replace**\ () and **bpf_l4_csum_replace**\ (), to
1151  *              which one can feed in the difference computed with
1152  *              **bpf_csum_diff**\ ().
1153  *      Return
1154  *              The checksum result, or a negative error code in case of
1155  *              failure.
1156  *
1157  * int bpf_skb_get_tunnel_opt(struct sk_buff *skb, u8 *opt, u32 size)
1158  *      Description
1159  *              Retrieve tunnel options metadata for the packet associated to
1160  *              *skb*, and store the raw tunnel option data to the buffer *opt*
1161  *              of *size*.
1162  *
1163  *              This helper can be used with encapsulation devices that can
1164  *              operate in "collect metadata" mode (please refer to the related
1165  *              note in the description of **bpf_skb_get_tunnel_key**\ () for
1166  *              more details). A particular example where this can be used is
1167  *              in combination with the Geneve encapsulation protocol, where it
1168  *              allows for pushing (with **bpf_skb_get_tunnel_opt**\ () helper)
1169  *              and retrieving arbitrary TLVs (Type-Length-Value headers) from
1170  *              the eBPF program. This allows for full customization of these
1171  *              headers.
1172  *      Return
1173  *              The size of the option data retrieved.
1174  *
1175  * int bpf_skb_set_tunnel_opt(struct sk_buff *skb, u8 *opt, u32 size)
1176  *      Description
1177  *              Set tunnel options metadata for the packet associated to *skb*
1178  *              to the option data contained in the raw buffer *opt* of *size*.
1179  *
1180  *              See also the description of the **bpf_skb_get_tunnel_opt**\ ()
1181  *              helper for additional information.
1182  *      Return
1183  *              0 on success, or a negative error in case of failure.
1184  *
1185  * int bpf_skb_change_proto(struct sk_buff *skb, __be16 proto, u64 flags)
1186  *      Description
1187  *              Change the protocol of the *skb* to *proto*. Currently
1188  *              supported are transition from IPv4 to IPv6, and from IPv6 to
1189  *              IPv4. The helper takes care of the groundwork for the
1190  *              transition, including resizing the socket buffer. The eBPF
1191  *              program is expected to fill the new headers, if any, via
1192  *              **skb_store_bytes**\ () and to recompute the checksums with
1193  *              **bpf_l3_csum_replace**\ () and **bpf_l4_csum_replace**\
1194  *              (). The main case for this helper is to perform NAT64
1195  *              operations out of an eBPF program.
1196  *
1197  *              Internally, the GSO type is marked as dodgy so that headers are
1198  *              checked and segments are recalculated by the GSO/GRO engine.
1199  *              The size for GSO target is adapted as well.
1200  *
1201  *              All values for *flags* are reserved for future usage, and must
1202  *              be left at zero.
1203  *
1204  *              A call to this helper is susceptible to change the underlying
1205  *              packet buffer. Therefore, at load time, all checks on pointers
1206  *              previously done by the verifier are invalidated and must be
1207  *              performed again, if the helper is used in combination with
1208  *              direct packet access.
1209  *      Return
1210  *              0 on success, or a negative error in case of failure.
1211  *
1212  * int bpf_skb_change_type(struct sk_buff *skb, u32 type)
1213  *      Description
1214  *              Change the packet type for the packet associated to *skb*. This
1215  *              comes down to setting *skb*\ **->pkt_type** to *type*, except
1216  *              the eBPF program does not have a write access to *skb*\
1217  *              **->pkt_type** beside this helper. Using a helper here allows
1218  *              for graceful handling of errors.
1219  *
1220  *              The major use case is to change incoming *skb*s to
1221  *              **PACKET_HOST** in a programmatic way instead of having to
1222  *              recirculate via **redirect**\ (..., **BPF_F_INGRESS**), for
1223  *              example.
1224  *
1225  *              Note that *type* only allows certain values. At this time, they
1226  *              are:
1227  *
1228  *              **PACKET_HOST**
1229  *                      Packet is for us.
1230  *              **PACKET_BROADCAST**
1231  *                      Send packet to all.
1232  *              **PACKET_MULTICAST**
1233  *                      Send packet to group.
1234  *              **PACKET_OTHERHOST**
1235  *                      Send packet to someone else.
1236  *      Return
1237  *              0 on success, or a negative error in case of failure.
1238  *
1239  * int bpf_skb_under_cgroup(struct sk_buff *skb, struct bpf_map *map, u32 index)
1240  *      Description
1241  *              Check whether *skb* is a descendant of the cgroup2 held by
1242  *              *map* of type **BPF_MAP_TYPE_CGROUP_ARRAY**, at *index*.
1243  *      Return
1244  *              The return value depends on the result of the test, and can be:
1245  *
1246  *              * 0, if the *skb* failed the cgroup2 descendant test.
1247  *              * 1, if the *skb* succeeded the cgroup2 descendant test.
1248  *              * A negative error code, if an error occurred.
1249  *
1250  * u32 bpf_get_hash_recalc(struct sk_buff *skb)
1251  *      Description
1252  *              Retrieve the hash of the packet, *skb*\ **->hash**. If it is
1253  *              not set, in particular if the hash was cleared due to mangling,
1254  *              recompute this hash. Later accesses to the hash can be done
1255  *              directly with *skb*\ **->hash**.
1256  *
1257  *              Calling **bpf_set_hash_invalid**\ (), changing a packet
1258  *              prototype with **bpf_skb_change_proto**\ (), or calling
1259  *              **bpf_skb_store_bytes**\ () with the
1260  *              **BPF_F_INVALIDATE_HASH** are actions susceptible to clear
1261  *              the hash and to trigger a new computation for the next call to
1262  *              **bpf_get_hash_recalc**\ ().
1263  *      Return
1264  *              The 32-bit hash.
1265  *
1266  * u64 bpf_get_current_task(void)
1267  *      Return
1268  *              A pointer to the current task struct.
1269  *
1270  * int bpf_probe_write_user(void *dst, const void *src, u32 len)
1271  *      Description
1272  *              Attempt in a safe way to write *len* bytes from the buffer
1273  *              *src* to *dst* in memory. It only works for threads that are in
1274  *              user context, and *dst* must be a valid user space address.
1275  *
1276  *              This helper should not be used to implement any kind of
1277  *              security mechanism because of TOC-TOU attacks, but rather to
1278  *              debug, divert, and manipulate execution of semi-cooperative
1279  *              processes.
1280  *
1281  *              Keep in mind that this feature is meant for experiments, and it
1282  *              has a risk of crashing the system and running programs.
1283  *              Therefore, when an eBPF program using this helper is attached,
1284  *              a warning including PID and process name is printed to kernel
1285  *              logs.
1286  *      Return
1287  *              0 on success, or a negative error in case of failure.
1288  *
1289  * int bpf_current_task_under_cgroup(struct bpf_map *map, u32 index)
1290  *      Description
1291  *              Check whether the probe is being run is the context of a given
1292  *              subset of the cgroup2 hierarchy. The cgroup2 to test is held by
1293  *              *map* of type **BPF_MAP_TYPE_CGROUP_ARRAY**, at *index*.
1294  *      Return
1295  *              The return value depends on the result of the test, and can be:
1296  *
1297  *              * 0, if the *skb* task belongs to the cgroup2.
1298  *              * 1, if the *skb* task does not belong to the cgroup2.
1299  *              * A negative error code, if an error occurred.
1300  *
1301  * int bpf_skb_change_tail(struct sk_buff *skb, u32 len, u64 flags)
1302  *      Description
1303  *              Resize (trim or grow) the packet associated to *skb* to the
1304  *              new *len*. The *flags* are reserved for future usage, and must
1305  *              be left at zero.
1306  *
1307  *              The basic idea is that the helper performs the needed work to
1308  *              change the size of the packet, then the eBPF program rewrites
1309  *              the rest via helpers like **bpf_skb_store_bytes**\ (),
1310  *              **bpf_l3_csum_replace**\ (), **bpf_l3_csum_replace**\ ()
1311  *              and others. This helper is a slow path utility intended for
1312  *              replies with control messages. And because it is targeted for
1313  *              slow path, the helper itself can afford to be slow: it
1314  *              implicitly linearizes, unclones and drops offloads from the
1315  *              *skb*.
1316  *
1317  *              A call to this helper is susceptible to change the underlying
1318  *              packet buffer. Therefore, at load time, all checks on pointers
1319  *              previously done by the verifier are invalidated and must be
1320  *              performed again, if the helper is used in combination with
1321  *              direct packet access.
1322  *      Return
1323  *              0 on success, or a negative error in case of failure.
1324  *
1325  * int bpf_skb_pull_data(struct sk_buff *skb, u32 len)
1326  *      Description
1327  *              Pull in non-linear data in case the *skb* is non-linear and not
1328  *              all of *len* are part of the linear section. Make *len* bytes
1329  *              from *skb* readable and writable. If a zero value is passed for
1330  *              *len*, then the whole length of the *skb* is pulled.
1331  *
1332  *              This helper is only needed for reading and writing with direct
1333  *              packet access.
1334  *
1335  *              For direct packet access, testing that offsets to access
1336  *              are within packet boundaries (test on *skb*\ **->data_end**) is
1337  *              susceptible to fail if offsets are invalid, or if the requested
1338  *              data is in non-linear parts of the *skb*. On failure the
1339  *              program can just bail out, or in the case of a non-linear
1340  *              buffer, use a helper to make the data available. The
1341  *              **bpf_skb_load_bytes**\ () helper is a first solution to access
1342  *              the data. Another one consists in using **bpf_skb_pull_data**
1343  *              to pull in once the non-linear parts, then retesting and
1344  *              eventually access the data.
1345  *
1346  *              At the same time, this also makes sure the *skb* is uncloned,
1347  *              which is a necessary condition for direct write. As this needs
1348  *              to be an invariant for the write part only, the verifier
1349  *              detects writes and adds a prologue that is calling
1350  *              **bpf_skb_pull_data()** to effectively unclone the *skb* from
1351  *              the very beginning in case it is indeed cloned.
1352  *
1353  *              A call to this helper is susceptible to change the underlying
1354  *              packet buffer. Therefore, at load time, all checks on pointers
1355  *              previously done by the verifier are invalidated and must be
1356  *              performed again, if the helper is used in combination with
1357  *              direct packet access.
1358  *      Return
1359  *              0 on success, or a negative error in case of failure.
1360  *
1361  * s64 bpf_csum_update(struct sk_buff *skb, __wsum csum)
1362  *      Description
1363  *              Add the checksum *csum* into *skb*\ **->csum** in case the
1364  *              driver has supplied a checksum for the entire packet into that
1365  *              field. Return an error otherwise. This helper is intended to be
1366  *              used in combination with **bpf_csum_diff**\ (), in particular
1367  *              when the checksum needs to be updated after data has been
1368  *              written into the packet through direct packet access.
1369  *      Return
1370  *              The checksum on success, or a negative error code in case of
1371  *              failure.
1372  *
1373  * void bpf_set_hash_invalid(struct sk_buff *skb)
1374  *      Description
1375  *              Invalidate the current *skb*\ **->hash**. It can be used after
1376  *              mangling on headers through direct packet access, in order to
1377  *              indicate that the hash is outdated and to trigger a
1378  *              recalculation the next time the kernel tries to access this
1379  *              hash or when the **bpf_get_hash_recalc**\ () helper is called.
1380  *
1381  * int bpf_get_numa_node_id(void)
1382  *      Description
1383  *              Return the id of the current NUMA node. The primary use case
1384  *              for this helper is the selection of sockets for the local NUMA
1385  *              node, when the program is attached to sockets using the
1386  *              **SO_ATTACH_REUSEPORT_EBPF** option (see also **socket(7)**),
1387  *              but the helper is also available to other eBPF program types,
1388  *              similarly to **bpf_get_smp_processor_id**\ ().
1389  *      Return
1390  *              The id of current NUMA node.
1391  *
1392  * int bpf_skb_change_head(struct sk_buff *skb, u32 len, u64 flags)
1393  *      Description
1394  *              Grows headroom of packet associated to *skb* and adjusts the
1395  *              offset of the MAC header accordingly, adding *len* bytes of
1396  *              space. It automatically extends and reallocates memory as
1397  *              required.
1398  *
1399  *              This helper can be used on a layer 3 *skb* to push a MAC header
1400  *              for redirection into a layer 2 device.
1401  *
1402  *              All values for *flags* are reserved for future usage, and must
1403  *              be left at zero.
1404  *
1405  *              A call to this helper is susceptible to change the underlying
1406  *              packet buffer. Therefore, at load time, all checks on pointers
1407  *              previously done by the verifier are invalidated and must be
1408  *              performed again, if the helper is used in combination with
1409  *              direct packet access.
1410  *      Return
1411  *              0 on success, or a negative error in case of failure.
1412  *
1413  * int bpf_xdp_adjust_head(struct xdp_buff *xdp_md, int delta)
1414  *      Description
1415  *              Adjust (move) *xdp_md*\ **->data** by *delta* bytes. Note that
1416  *              it is possible to use a negative value for *delta*. This helper
1417  *              can be used to prepare the packet for pushing or popping
1418  *              headers.
1419  *
1420  *              A call to this helper is susceptible to change the underlying
1421  *              packet buffer. Therefore, at load time, all checks on pointers
1422  *              previously done by the verifier are invalidated and must be
1423  *              performed again, if the helper is used in combination with
1424  *              direct packet access.
1425  *      Return
1426  *              0 on success, or a negative error in case of failure.
1427  *
1428  * int bpf_probe_read_str(void *dst, int size, const void *unsafe_ptr)
1429  *      Description
1430  *              Copy a NUL terminated string from an unsafe address
1431  *              *unsafe_ptr* to *dst*. The *size* should include the
1432  *              terminating NUL byte. In case the string length is smaller than
1433  *              *size*, the target is not padded with further NUL bytes. If the
1434  *              string length is larger than *size*, just *size*-1 bytes are
1435  *              copied and the last byte is set to NUL.
1436  *
1437  *              On success, the length of the copied string is returned. This
1438  *              makes this helper useful in tracing programs for reading
1439  *              strings, and more importantly to get its length at runtime. See
1440  *              the following snippet:
1441  *
1442  *              ::
1443  *
1444  *                      SEC("kprobe/sys_open")
1445  *                      void bpf_sys_open(struct pt_regs *ctx)
1446  *                      {
1447  *                              char buf[PATHLEN]; // PATHLEN is defined to 256
1448  *                              int res = bpf_probe_read_str(buf, sizeof(buf),
1449  *                                                           ctx->di);
1450  *
1451  *                              // Consume buf, for example push it to
1452  *                              // userspace via bpf_perf_event_output(); we
1453  *                              // can use res (the string length) as event
1454  *                              // size, after checking its boundaries.
1455  *                      }
1456  *
1457  *              In comparison, using **bpf_probe_read()** helper here instead
1458  *              to read the string would require to estimate the length at
1459  *              compile time, and would often result in copying more memory
1460  *              than necessary.
1461  *
1462  *              Another useful use case is when parsing individual process
1463  *              arguments or individual environment variables navigating
1464  *              *current*\ **->mm->arg_start** and *current*\
1465  *              **->mm->env_start**: using this helper and the return value,
1466  *              one can quickly iterate at the right offset of the memory area.
1467  *      Return
1468  *              On success, the strictly positive length of the string,
1469  *              including the trailing NUL character. On error, a negative
1470  *              value.
1471  *
1472  * u64 bpf_get_socket_cookie(struct sk_buff *skb)
1473  *      Description
1474  *              If the **struct sk_buff** pointed by *skb* has a known socket,
1475  *              retrieve the cookie (generated by the kernel) of this socket.
1476  *              If no cookie has been set yet, generate a new cookie. Once
1477  *              generated, the socket cookie remains stable for the life of the
1478  *              socket. This helper can be useful for monitoring per socket
1479  *              networking traffic statistics as it provides a global socket
1480  *              identifier that can be assumed unique.
1481  *      Return
1482  *              A 8-byte long non-decreasing number on success, or 0 if the
1483  *              socket field is missing inside *skb*.
1484  *
1485  * u64 bpf_get_socket_cookie(struct bpf_sock_addr *ctx)
1486  *      Description
1487  *              Equivalent to bpf_get_socket_cookie() helper that accepts
1488  *              *skb*, but gets socket from **struct bpf_sock_addr** context.
1489  *      Return
1490  *              A 8-byte long non-decreasing number.
1491  *
1492  * u64 bpf_get_socket_cookie(struct bpf_sock_ops *ctx)
1493  *      Description
1494  *              Equivalent to bpf_get_socket_cookie() helper that accepts
1495  *              *skb*, but gets socket from **struct bpf_sock_ops** context.
1496  *      Return
1497  *              A 8-byte long non-decreasing number.
1498  *
1499  * u32 bpf_get_socket_uid(struct sk_buff *skb)
1500  *      Return
1501  *              The owner UID of the socket associated to *skb*. If the socket
1502  *              is **NULL**, or if it is not a full socket (i.e. if it is a
1503  *              time-wait or a request socket instead), **overflowuid** value
1504  *              is returned (note that **overflowuid** might also be the actual
1505  *              UID value for the socket).
1506  *
1507  * u32 bpf_set_hash(struct sk_buff *skb, u32 hash)
1508  *      Description
1509  *              Set the full hash for *skb* (set the field *skb*\ **->hash**)
1510  *              to value *hash*.
1511  *      Return
1512  *              0
1513  *
1514  * int bpf_setsockopt(struct bpf_sock_ops *bpf_socket, int level, int optname, char *optval, int optlen)
1515  *      Description
1516  *              Emulate a call to **setsockopt()** on the socket associated to
1517  *              *bpf_socket*, which must be a full socket. The *level* at
1518  *              which the option resides and the name *optname* of the option
1519  *              must be specified, see **setsockopt(2)** for more information.
1520  *              The option value of length *optlen* is pointed by *optval*.
1521  *
1522  *              This helper actually implements a subset of **setsockopt()**.
1523  *              It supports the following *level*\ s:
1524  *
1525  *              * **SOL_SOCKET**, which supports the following *optname*\ s:
1526  *                **SO_RCVBUF**, **SO_SNDBUF**, **SO_MAX_PACING_RATE**,
1527  *                **SO_PRIORITY**, **SO_RCVLOWAT**, **SO_MARK**.
1528  *              * **IPPROTO_TCP**, which supports the following *optname*\ s:
1529  *                **TCP_CONGESTION**, **TCP_BPF_IW**,
1530  *                **TCP_BPF_SNDCWND_CLAMP**.
1531  *              * **IPPROTO_IP**, which supports *optname* **IP_TOS**.
1532  *              * **IPPROTO_IPV6**, which supports *optname* **IPV6_TCLASS**.
1533  *      Return
1534  *              0 on success, or a negative error in case of failure.
1535  *
1536  * int bpf_skb_adjust_room(struct sk_buff *skb, s32 len_diff, u32 mode, u64 flags)
1537  *      Description
1538  *              Grow or shrink the room for data in the packet associated to
1539  *              *skb* by *len_diff*, and according to the selected *mode*.
1540  *
1541  *              There are two supported modes at this time:
1542  *
1543  *              * **BPF_ADJ_ROOM_MAC**: Adjust room at the mac layer
1544  *                (room space is added or removed below the layer 2 header).
1545  *
1546  *              * **BPF_ADJ_ROOM_NET**: Adjust room at the network layer
1547  *                (room space is added or removed below the layer 3 header).
1548  *
1549  *              The following flags are supported at this time:
1550  *
1551  *              * **BPF_F_ADJ_ROOM_FIXED_GSO**: Do not adjust gso_size.
1552  *                Adjusting mss in this way is not allowed for datagrams.
1553  *
1554  *              * **BPF_F_ADJ_ROOM_ENCAP_L3_IPV4**,
1555  *                **BPF_F_ADJ_ROOM_ENCAP_L3_IPV6**:
1556  *                Any new space is reserved to hold a tunnel header.
1557  *                Configure skb offsets and other fields accordingly.
1558  *
1559  *              * **BPF_F_ADJ_ROOM_ENCAP_L4_GRE**,
1560  *                **BPF_F_ADJ_ROOM_ENCAP_L4_UDP**:
1561  *                Use with ENCAP_L3 flags to further specify the tunnel type.
1562  *
1563  *              * **BPF_F_ADJ_ROOM_ENCAP_L2**\ (*len*):
1564  *                Use with ENCAP_L3/L4 flags to further specify the tunnel
1565  *                type; *len* is the length of the inner MAC header.
1566  *
1567  *              A call to this helper is susceptible to change the underlying
1568  *              packet buffer. Therefore, at load time, all checks on pointers
1569  *              previously done by the verifier are invalidated and must be
1570  *              performed again, if the helper is used in combination with
1571  *              direct packet access.
1572  *      Return
1573  *              0 on success, or a negative error in case of failure.
1574  *
1575  * int bpf_redirect_map(struct bpf_map *map, u32 key, u64 flags)
1576  *      Description
1577  *              Redirect the packet to the endpoint referenced by *map* at
1578  *              index *key*. Depending on its type, this *map* can contain
1579  *              references to net devices (for forwarding packets through other
1580  *              ports), or to CPUs (for redirecting XDP frames to another CPU;
1581  *              but this is only implemented for native XDP (with driver
1582  *              support) as of this writing).
1583  *
1584  *              The lower two bits of *flags* are used as the return code if
1585  *              the map lookup fails. This is so that the return value can be
1586  *              one of the XDP program return codes up to XDP_TX, as chosen by
1587  *              the caller. Any higher bits in the *flags* argument must be
1588  *              unset.
1589  *
1590  *              When used to redirect packets to net devices, this helper
1591  *              provides a high performance increase over **bpf_redirect**\ ().
1592  *              This is due to various implementation details of the underlying
1593  *              mechanisms, one of which is the fact that **bpf_redirect_map**\
1594  *              () tries to send packet as a "bulk" to the device.
1595  *      Return
1596  *              **XDP_REDIRECT** on success, or **XDP_ABORTED** on error.
1597  *
1598  * int bpf_sk_redirect_map(struct bpf_map *map, u32 key, u64 flags)
1599  *      Description
1600  *              Redirect the packet to the socket referenced by *map* (of type
1601  *              **BPF_MAP_TYPE_SOCKMAP**) at index *key*. Both ingress and
1602  *              egress interfaces can be used for redirection. The
1603  *              **BPF_F_INGRESS** value in *flags* is used to make the
1604  *              distinction (ingress path is selected if the flag is present,
1605  *              egress path otherwise). This is the only flag supported for now.
1606  *      Return
1607  *              **SK_PASS** on success, or **SK_DROP** on error.
1608  *
1609  * int bpf_sock_map_update(struct bpf_sock_ops *skops, struct bpf_map *map, void *key, u64 flags)
1610  *      Description
1611  *              Add an entry to, or update a *map* referencing sockets. The
1612  *              *skops* is used as a new value for the entry associated to
1613  *              *key*. *flags* is one of:
1614  *
1615  *              **BPF_NOEXIST**
1616  *                      The entry for *key* must not exist in the map.
1617  *              **BPF_EXIST**
1618  *                      The entry for *key* must already exist in the map.
1619  *              **BPF_ANY**
1620  *                      No condition on the existence of the entry for *key*.
1621  *
1622  *              If the *map* has eBPF programs (parser and verdict), those will
1623  *              be inherited by the socket being added. If the socket is
1624  *              already attached to eBPF programs, this results in an error.
1625  *      Return
1626  *              0 on success, or a negative error in case of failure.
1627  *
1628  * int bpf_xdp_adjust_meta(struct xdp_buff *xdp_md, int delta)
1629  *      Description
1630  *              Adjust the address pointed by *xdp_md*\ **->data_meta** by
1631  *              *delta* (which can be positive or negative). Note that this
1632  *              operation modifies the address stored in *xdp_md*\ **->data**,
1633  *              so the latter must be loaded only after the helper has been
1634  *              called.
1635  *
1636  *              The use of *xdp_md*\ **->data_meta** is optional and programs
1637  *              are not required to use it. The rationale is that when the
1638  *              packet is processed with XDP (e.g. as DoS filter), it is
1639  *              possible to push further meta data along with it before passing
1640  *              to the stack, and to give the guarantee that an ingress eBPF
1641  *              program attached as a TC classifier on the same device can pick
1642  *              this up for further post-processing. Since TC works with socket
1643  *              buffers, it remains possible to set from XDP the **mark** or
1644  *              **priority** pointers, or other pointers for the socket buffer.
1645  *              Having this scratch space generic and programmable allows for
1646  *              more flexibility as the user is free to store whatever meta
1647  *              data they need.
1648  *
1649  *              A call to this helper is susceptible to change the underlying
1650  *              packet buffer. Therefore, at load time, all checks on pointers
1651  *              previously done by the verifier are invalidated and must be
1652  *              performed again, if the helper is used in combination with
1653  *              direct packet access.
1654  *      Return
1655  *              0 on success, or a negative error in case of failure.
1656  *
1657  * int bpf_perf_event_read_value(struct bpf_map *map, u64 flags, struct bpf_perf_event_value *buf, u32 buf_size)
1658  *      Description
1659  *              Read the value of a perf event counter, and store it into *buf*
1660  *              of size *buf_size*. This helper relies on a *map* of type
1661  *              **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. The nature of the perf event
1662  *              counter is selected when *map* is updated with perf event file
1663  *              descriptors. The *map* is an array whose size is the number of
1664  *              available CPUs, and each cell contains a value relative to one
1665  *              CPU. The value to retrieve is indicated by *flags*, that
1666  *              contains the index of the CPU to look up, masked with
1667  *              **BPF_F_INDEX_MASK**. Alternatively, *flags* can be set to
1668  *              **BPF_F_CURRENT_CPU** to indicate that the value for the
1669  *              current CPU should be retrieved.
1670  *
1671  *              This helper behaves in a way close to
1672  *              **bpf_perf_event_read**\ () helper, save that instead of
1673  *              just returning the value observed, it fills the *buf*
1674  *              structure. This allows for additional data to be retrieved: in
1675  *              particular, the enabled and running times (in *buf*\
1676  *              **->enabled** and *buf*\ **->running**, respectively) are
1677  *              copied. In general, **bpf_perf_event_read_value**\ () is
1678  *              recommended over **bpf_perf_event_read**\ (), which has some
1679  *              ABI issues and provides fewer functionalities.
1680  *
1681  *              These values are interesting, because hardware PMU (Performance
1682  *              Monitoring Unit) counters are limited resources. When there are
1683  *              more PMU based perf events opened than available counters,
1684  *              kernel will multiplex these events so each event gets certain
1685  *              percentage (but not all) of the PMU time. In case that
1686  *              multiplexing happens, the number of samples or counter value
1687  *              will not reflect the case compared to when no multiplexing
1688  *              occurs. This makes comparison between different runs difficult.
1689  *              Typically, the counter value should be normalized before
1690  *              comparing to other experiments. The usual normalization is done
1691  *              as follows.
1692  *
1693  *              ::
1694  *
1695  *                      normalized_counter = counter * t_enabled / t_running
1696  *
1697  *              Where t_enabled is the time enabled for event and t_running is
1698  *              the time running for event since last normalization. The
1699  *              enabled and running times are accumulated since the perf event
1700  *              open. To achieve scaling factor between two invocations of an
1701  *              eBPF program, users can can use CPU id as the key (which is
1702  *              typical for perf array usage model) to remember the previous
1703  *              value and do the calculation inside the eBPF program.
1704  *      Return
1705  *              0 on success, or a negative error in case of failure.
1706  *
1707  * int bpf_perf_prog_read_value(struct bpf_perf_event_data *ctx, struct bpf_perf_event_value *buf, u32 buf_size)
1708  *      Description
1709  *              For en eBPF program attached to a perf event, retrieve the
1710  *              value of the event counter associated to *ctx* and store it in
1711  *              the structure pointed by *buf* and of size *buf_size*. Enabled
1712  *              and running times are also stored in the structure (see
1713  *              description of helper **bpf_perf_event_read_value**\ () for
1714  *              more details).
1715  *      Return
1716  *              0 on success, or a negative error in case of failure.
1717  *
1718  * int bpf_getsockopt(struct bpf_sock_ops *bpf_socket, int level, int optname, char *optval, int optlen)
1719  *      Description
1720  *              Emulate a call to **getsockopt()** on the socket associated to
1721  *              *bpf_socket*, which must be a full socket. The *level* at
1722  *              which the option resides and the name *optname* of the option
1723  *              must be specified, see **getsockopt(2)** for more information.
1724  *              The retrieved value is stored in the structure pointed by
1725  *              *opval* and of length *optlen*.
1726  *
1727  *              This helper actually implements a subset of **getsockopt()**.
1728  *              It supports the following *level*\ s:
1729  *
1730  *              * **IPPROTO_TCP**, which supports *optname*
1731  *                **TCP_CONGESTION**.
1732  *              * **IPPROTO_IP**, which supports *optname* **IP_TOS**.
1733  *              * **IPPROTO_IPV6**, which supports *optname* **IPV6_TCLASS**.
1734  *      Return
1735  *              0 on success, or a negative error in case of failure.
1736  *
1737  * int bpf_override_return(struct pt_regs *regs, u64 rc)
1738  *      Description
1739  *              Used for error injection, this helper uses kprobes to override
1740  *              the return value of the probed function, and to set it to *rc*.
1741  *              The first argument is the context *regs* on which the kprobe
1742  *              works.
1743  *
1744  *              This helper works by setting setting the PC (program counter)
1745  *              to an override function which is run in place of the original
1746  *              probed function. This means the probed function is not run at
1747  *              all. The replacement function just returns with the required
1748  *              value.
1749  *
1750  *              This helper has security implications, and thus is subject to
1751  *              restrictions. It is only available if the kernel was compiled
1752  *              with the **CONFIG_BPF_KPROBE_OVERRIDE** configuration
1753  *              option, and in this case it only works on functions tagged with
1754  *              **ALLOW_ERROR_INJECTION** in the kernel code.
1755  *
1756  *              Also, the helper is only available for the architectures having
1757  *              the CONFIG_FUNCTION_ERROR_INJECTION option. As of this writing,
1758  *              x86 architecture is the only one to support this feature.
1759  *      Return
1760  *              0
1761  *
1762  * int bpf_sock_ops_cb_flags_set(struct bpf_sock_ops *bpf_sock, int argval)
1763  *      Description
1764  *              Attempt to set the value of the **bpf_sock_ops_cb_flags** field
1765  *              for the full TCP socket associated to *bpf_sock_ops* to
1766  *              *argval*.
1767  *
1768  *              The primary use of this field is to determine if there should
1769  *              be calls to eBPF programs of type
1770  *              **BPF_PROG_TYPE_SOCK_OPS** at various points in the TCP
1771  *              code. A program of the same type can change its value, per
1772  *              connection and as necessary, when the connection is
1773  *              established. This field is directly accessible for reading, but
1774  *              this helper must be used for updates in order to return an
1775  *              error if an eBPF program tries to set a callback that is not
1776  *              supported in the current kernel.
1777  *
1778  *              *argval* is a flag array which can combine these flags:
1779  *
1780  *              * **BPF_SOCK_OPS_RTO_CB_FLAG** (retransmission time out)
1781  *              * **BPF_SOCK_OPS_RETRANS_CB_FLAG** (retransmission)
1782  *              * **BPF_SOCK_OPS_STATE_CB_FLAG** (TCP state change)
1783  *              * **BPF_SOCK_OPS_RTT_CB_FLAG** (every RTT)
1784  *
1785  *              Therefore, this function can be used to clear a callback flag by
1786  *              setting the appropriate bit to zero. e.g. to disable the RTO
1787  *              callback:
1788  *
1789  *              **bpf_sock_ops_cb_flags_set(bpf_sock,**
1790  *                      **bpf_sock->bpf_sock_ops_cb_flags & ~BPF_SOCK_OPS_RTO_CB_FLAG)**
1791  *
1792  *              Here are some examples of where one could call such eBPF
1793  *              program:
1794  *
1795  *              * When RTO fires.
1796  *              * When a packet is retransmitted.
1797  *              * When the connection terminates.
1798  *              * When a packet is sent.
1799  *              * When a packet is received.
1800  *      Return
1801  *              Code **-EINVAL** if the socket is not a full TCP socket;
1802  *              otherwise, a positive number containing the bits that could not
1803  *              be set is returned (which comes down to 0 if all bits were set
1804  *              as required).
1805  *
1806  * int bpf_msg_redirect_map(struct sk_msg_buff *msg, struct bpf_map *map, u32 key, u64 flags)
1807  *      Description
1808  *              This helper is used in programs implementing policies at the
1809  *              socket level. If the message *msg* is allowed to pass (i.e. if
1810  *              the verdict eBPF program returns **SK_PASS**), redirect it to
1811  *              the socket referenced by *map* (of type
1812  *              **BPF_MAP_TYPE_SOCKMAP**) at index *key*. Both ingress and
1813  *              egress interfaces can be used for redirection. The
1814  *              **BPF_F_INGRESS** value in *flags* is used to make the
1815  *              distinction (ingress path is selected if the flag is present,
1816  *              egress path otherwise). This is the only flag supported for now.
1817  *      Return
1818  *              **SK_PASS** on success, or **SK_DROP** on error.
1819  *
1820  * int bpf_msg_apply_bytes(struct sk_msg_buff *msg, u32 bytes)
1821  *      Description
1822  *              For socket policies, apply the verdict of the eBPF program to
1823  *              the next *bytes* (number of bytes) of message *msg*.
1824  *
1825  *              For example, this helper can be used in the following cases:
1826  *
1827  *              * A single **sendmsg**\ () or **sendfile**\ () system call
1828  *                contains multiple logical messages that the eBPF program is
1829  *                supposed to read and for which it should apply a verdict.
1830  *              * An eBPF program only cares to read the first *bytes* of a
1831  *                *msg*. If the message has a large payload, then setting up
1832  *                and calling the eBPF program repeatedly for all bytes, even
1833  *                though the verdict is already known, would create unnecessary
1834  *                overhead.
1835  *
1836  *              When called from within an eBPF program, the helper sets a
1837  *              counter internal to the BPF infrastructure, that is used to
1838  *              apply the last verdict to the next *bytes*. If *bytes* is
1839  *              smaller than the current data being processed from a
1840  *              **sendmsg**\ () or **sendfile**\ () system call, the first
1841  *              *bytes* will be sent and the eBPF program will be re-run with
1842  *              the pointer for start of data pointing to byte number *bytes*
1843  *              **+ 1**. If *bytes* is larger than the current data being
1844  *              processed, then the eBPF verdict will be applied to multiple
1845  *              **sendmsg**\ () or **sendfile**\ () calls until *bytes* are
1846  *              consumed.
1847  *
1848  *              Note that if a socket closes with the internal counter holding
1849  *              a non-zero value, this is not a problem because data is not
1850  *              being buffered for *bytes* and is sent as it is received.
1851  *      Return
1852  *              0
1853  *
1854  * int bpf_msg_cork_bytes(struct sk_msg_buff *msg, u32 bytes)
1855  *      Description
1856  *              For socket policies, prevent the execution of the verdict eBPF
1857  *              program for message *msg* until *bytes* (byte number) have been
1858  *              accumulated.
1859  *
1860  *              This can be used when one needs a specific number of bytes
1861  *              before a verdict can be assigned, even if the data spans
1862  *              multiple **sendmsg**\ () or **sendfile**\ () calls. The extreme
1863  *              case would be a user calling **sendmsg**\ () repeatedly with
1864  *              1-byte long message segments. Obviously, this is bad for
1865  *              performance, but it is still valid. If the eBPF program needs
1866  *              *bytes* bytes to validate a header, this helper can be used to
1867  *              prevent the eBPF program to be called again until *bytes* have
1868  *              been accumulated.
1869  *      Return
1870  *              0
1871  *
1872  * int bpf_msg_pull_data(struct sk_msg_buff *msg, u32 start, u32 end, u64 flags)
1873  *      Description
1874  *              For socket policies, pull in non-linear data from user space
1875  *              for *msg* and set pointers *msg*\ **->data** and *msg*\
1876  *              **->data_end** to *start* and *end* bytes offsets into *msg*,
1877  *              respectively.
1878  *
1879  *              If a program of type **BPF_PROG_TYPE_SK_MSG** is run on a
1880  *              *msg* it can only parse data that the (**data**, **data_end**)
1881  *              pointers have already consumed. For **sendmsg**\ () hooks this
1882  *              is likely the first scatterlist element. But for calls relying
1883  *              on the **sendpage** handler (e.g. **sendfile**\ ()) this will
1884  *              be the range (**0**, **0**) because the data is shared with
1885  *              user space and by default the objective is to avoid allowing
1886  *              user space to modify data while (or after) eBPF verdict is
1887  *              being decided. This helper can be used to pull in data and to
1888  *              set the start and end pointer to given values. Data will be
1889  *              copied if necessary (i.e. if data was not linear and if start
1890  *              and end pointers do not point to the same chunk).
1891  *
1892  *              A call to this helper is susceptible to change the underlying
1893  *              packet buffer. Therefore, at load time, all checks on pointers
1894  *              previously done by the verifier are invalidated and must be
1895  *              performed again, if the helper is used in combination with
1896  *              direct packet access.
1897  *
1898  *              All values for *flags* are reserved for future usage, and must
1899  *              be left at zero.
1900  *      Return
1901  *              0 on success, or a negative error in case of failure.
1902  *
1903  * int bpf_bind(struct bpf_sock_addr *ctx, struct sockaddr *addr, int addr_len)
1904  *      Description
1905  *              Bind the socket associated to *ctx* to the address pointed by
1906  *              *addr*, of length *addr_len*. This allows for making outgoing
1907  *              connection from the desired IP address, which can be useful for
1908  *              example when all processes inside a cgroup should use one
1909  *              single IP address on a host that has multiple IP configured.
1910  *
1911  *              This helper works for IPv4 and IPv6, TCP and UDP sockets. The
1912  *              domain (*addr*\ **->sa_family**) must be **AF_INET** (or
1913  *              **AF_INET6**). Looking for a free port to bind to can be
1914  *              expensive, therefore binding to port is not permitted by the
1915  *              helper: *addr*\ **->sin_port** (or **sin6_port**, respectively)
1916  *              must be set to zero.
1917  *      Return
1918  *              0 on success, or a negative error in case of failure.
1919  *
1920  * int bpf_xdp_adjust_tail(struct xdp_buff *xdp_md, int delta)
1921  *      Description
1922  *              Adjust (move) *xdp_md*\ **->data_end** by *delta* bytes. It is
1923  *              only possible to shrink the packet as of this writing,
1924  *              therefore *delta* must be a negative integer.
1925  *
1926  *              A call to this helper is susceptible to change the underlying
1927  *              packet buffer. Therefore, at load time, all checks on pointers
1928  *              previously done by the verifier are invalidated and must be
1929  *              performed again, if the helper is used in combination with
1930  *              direct packet access.
1931  *      Return
1932  *              0 on success, or a negative error in case of failure.
1933  *
1934  * int bpf_skb_get_xfrm_state(struct sk_buff *skb, u32 index, struct bpf_xfrm_state *xfrm_state, u32 size, u64 flags)
1935  *      Description
1936  *              Retrieve the XFRM state (IP transform framework, see also
1937  *              **ip-xfrm(8)**) at *index* in XFRM "security path" for *skb*.
1938  *
1939  *              The retrieved value is stored in the **struct bpf_xfrm_state**
1940  *              pointed by *xfrm_state* and of length *size*.
1941  *
1942  *              All values for *flags* are reserved for future usage, and must
1943  *              be left at zero.
1944  *
1945  *              This helper is available only if the kernel was compiled with
1946  *              **CONFIG_XFRM** configuration option.
1947  *      Return
1948  *              0 on success, or a negative error in case of failure.
1949  *
1950  * int bpf_get_stack(struct pt_regs *regs, void *buf, u32 size, u64 flags)
1951  *      Description
1952  *              Return a user or a kernel stack in bpf program provided buffer.
1953  *              To achieve this, the helper needs *ctx*, which is a pointer
1954  *              to the context on which the tracing program is executed.
1955  *              To store the stacktrace, the bpf program provides *buf* with
1956  *              a nonnegative *size*.
1957  *
1958  *              The last argument, *flags*, holds the number of stack frames to
1959  *              skip (from 0 to 255), masked with
1960  *              **BPF_F_SKIP_FIELD_MASK**. The next bits can be used to set
1961  *              the following flags:
1962  *
1963  *              **BPF_F_USER_STACK**
1964  *                      Collect a user space stack instead of a kernel stack.
1965  *              **BPF_F_USER_BUILD_ID**
1966  *                      Collect buildid+offset instead of ips for user stack,
1967  *                      only valid if **BPF_F_USER_STACK** is also specified.
1968  *
1969  *              **bpf_get_stack**\ () can collect up to
1970  *              **PERF_MAX_STACK_DEPTH** both kernel and user frames, subject
1971  *              to sufficient large buffer size. Note that
1972  *              this limit can be controlled with the **sysctl** program, and
1973  *              that it should be manually increased in order to profile long
1974  *              user stacks (such as stacks for Java programs). To do so, use:
1975  *
1976  *              ::
1977  *
1978  *                      # sysctl kernel.perf_event_max_stack=<new value>
1979  *      Return
1980  *              A non-negative value equal to or less than *size* on success,
1981  *              or a negative error in case of failure.
1982  *
1983  * int bpf_skb_load_bytes_relative(const struct sk_buff *skb, u32 offset, void *to, u32 len, u32 start_header)
1984  *      Description
1985  *              This helper is similar to **bpf_skb_load_bytes**\ () in that
1986  *              it provides an easy way to load *len* bytes from *offset*
1987  *              from the packet associated to *skb*, into the buffer pointed
1988  *              by *to*. The difference to **bpf_skb_load_bytes**\ () is that
1989  *              a fifth argument *start_header* exists in order to select a
1990  *              base offset to start from. *start_header* can be one of:
1991  *
1992  *              **BPF_HDR_START_MAC**
1993  *                      Base offset to load data from is *skb*'s mac header.
1994  *              **BPF_HDR_START_NET**
1995  *                      Base offset to load data from is *skb*'s network header.
1996  *
1997  *              In general, "direct packet access" is the preferred method to
1998  *              access packet data, however, this helper is in particular useful
1999  *              in socket filters where *skb*\ **->data** does not always point
2000  *              to the start of the mac header and where "direct packet access"
2001  *              is not available.
2002  *      Return
2003  *              0 on success, or a negative error in case of failure.
2004  *
2005  * int bpf_fib_lookup(void *ctx, struct bpf_fib_lookup *params, int plen, u32 flags)
2006  *      Description
2007  *              Do FIB lookup in kernel tables using parameters in *params*.
2008  *              If lookup is successful and result shows packet is to be
2009  *              forwarded, the neighbor tables are searched for the nexthop.
2010  *              If successful (ie., FIB lookup shows forwarding and nexthop
2011  *              is resolved), the nexthop address is returned in ipv4_dst
2012  *              or ipv6_dst based on family, smac is set to mac address of
2013  *              egress device, dmac is set to nexthop mac address, rt_metric
2014  *              is set to metric from route (IPv4/IPv6 only), and ifindex
2015  *              is set to the device index of the nexthop from the FIB lookup.
2016  *
2017  *              *plen* argument is the size of the passed in struct.
2018  *              *flags* argument can be a combination of one or more of the
2019  *              following values:
2020  *
2021  *              **BPF_FIB_LOOKUP_DIRECT**
2022  *                      Do a direct table lookup vs full lookup using FIB
2023  *                      rules.
2024  *              **BPF_FIB_LOOKUP_OUTPUT**
2025  *                      Perform lookup from an egress perspective (default is
2026  *                      ingress).
2027  *
2028  *              *ctx* is either **struct xdp_md** for XDP programs or
2029  *              **struct sk_buff** tc cls_act programs.
2030  *      Return
2031  *              * < 0 if any input argument is invalid
2032  *              *   0 on success (packet is forwarded, nexthop neighbor exists)
2033  *              * > 0 one of **BPF_FIB_LKUP_RET_** codes explaining why the
2034  *                packet is not forwarded or needs assist from full stack
2035  *
2036  * int bpf_sock_hash_update(struct bpf_sock_ops_kern *skops, struct bpf_map *map, void *key, u64 flags)
2037  *      Description
2038  *              Add an entry to, or update a sockhash *map* referencing sockets.
2039  *              The *skops* is used as a new value for the entry associated to
2040  *              *key*. *flags* is one of:
2041  *
2042  *              **BPF_NOEXIST**
2043  *                      The entry for *key* must not exist in the map.
2044  *              **BPF_EXIST**
2045  *                      The entry for *key* must already exist in the map.
2046  *              **BPF_ANY**
2047  *                      No condition on the existence of the entry for *key*.
2048  *
2049  *              If the *map* has eBPF programs (parser and verdict), those will
2050  *              be inherited by the socket being added. If the socket is
2051  *              already attached to eBPF programs, this results in an error.
2052  *      Return
2053  *              0 on success, or a negative error in case of failure.
2054  *
2055  * int bpf_msg_redirect_hash(struct sk_msg_buff *msg, struct bpf_map *map, void *key, u64 flags)
2056  *      Description
2057  *              This helper is used in programs implementing policies at the
2058  *              socket level. If the message *msg* is allowed to pass (i.e. if
2059  *              the verdict eBPF program returns **SK_PASS**), redirect it to
2060  *              the socket referenced by *map* (of type
2061  *              **BPF_MAP_TYPE_SOCKHASH**) using hash *key*. Both ingress and
2062  *              egress interfaces can be used for redirection. The
2063  *              **BPF_F_INGRESS** value in *flags* is used to make the
2064  *              distinction (ingress path is selected if the flag is present,
2065  *              egress path otherwise). This is the only flag supported for now.
2066  *      Return
2067  *              **SK_PASS** on success, or **SK_DROP** on error.
2068  *
2069  * int bpf_sk_redirect_hash(struct sk_buff *skb, struct bpf_map *map, void *key, u64 flags)
2070  *      Description
2071  *              This helper is used in programs implementing policies at the
2072  *              skb socket level. If the sk_buff *skb* is allowed to pass (i.e.
2073  *              if the verdeict eBPF program returns **SK_PASS**), redirect it
2074  *              to the socket referenced by *map* (of type
2075  *              **BPF_MAP_TYPE_SOCKHASH**) using hash *key*. Both ingress and
2076  *              egress interfaces can be used for redirection. The
2077  *              **BPF_F_INGRESS** value in *flags* is used to make the
2078  *              distinction (ingress path is selected if the flag is present,
2079  *              egress otherwise). This is the only flag supported for now.
2080  *      Return
2081  *              **SK_PASS** on success, or **SK_DROP** on error.
2082  *
2083  * int bpf_lwt_push_encap(struct sk_buff *skb, u32 type, void *hdr, u32 len)
2084  *      Description
2085  *              Encapsulate the packet associated to *skb* within a Layer 3
2086  *              protocol header. This header is provided in the buffer at
2087  *              address *hdr*, with *len* its size in bytes. *type* indicates
2088  *              the protocol of the header and can be one of:
2089  *
2090  *              **BPF_LWT_ENCAP_SEG6**
2091  *                      IPv6 encapsulation with Segment Routing Header
2092  *                      (**struct ipv6_sr_hdr**). *hdr* only contains the SRH,
2093  *                      the IPv6 header is computed by the kernel.
2094  *              **BPF_LWT_ENCAP_SEG6_INLINE**
2095  *                      Only works if *skb* contains an IPv6 packet. Insert a
2096  *                      Segment Routing Header (**struct ipv6_sr_hdr**) inside
2097  *                      the IPv6 header.
2098  *              **BPF_LWT_ENCAP_IP**
2099  *                      IP encapsulation (GRE/GUE/IPIP/etc). The outer header
2100  *                      must be IPv4 or IPv6, followed by zero or more
2101  *                      additional headers, up to **LWT_BPF_MAX_HEADROOM**
2102  *                      total bytes in all prepended headers. Please note that
2103  *                      if **skb_is_gso**\ (*skb*) is true, no more than two
2104  *                      headers can be prepended, and the inner header, if
2105  *                      present, should be either GRE or UDP/GUE.
2106  *
2107  *              **BPF_LWT_ENCAP_SEG6**\ \* types can be called by BPF programs
2108  *              of type **BPF_PROG_TYPE_LWT_IN**; **BPF_LWT_ENCAP_IP** type can
2109  *              be called by bpf programs of types **BPF_PROG_TYPE_LWT_IN** and
2110  *              **BPF_PROG_TYPE_LWT_XMIT**.
2111  *
2112  *              A call to this helper is susceptible to change the underlying
2113  *              packet buffer. Therefore, at load time, all checks on pointers
2114  *              previously done by the verifier are invalidated and must be
2115  *              performed again, if the helper is used in combination with
2116  *              direct packet access.
2117  *      Return
2118  *              0 on success, or a negative error in case of failure.
2119  *
2120  * int bpf_lwt_seg6_store_bytes(struct sk_buff *skb, u32 offset, const void *from, u32 len)
2121  *      Description
2122  *              Store *len* bytes from address *from* into the packet
2123  *              associated to *skb*, at *offset*. Only the flags, tag and TLVs
2124  *              inside the outermost IPv6 Segment Routing Header can be
2125  *              modified through this helper.
2126  *
2127  *              A call to this helper is susceptible to change the underlying
2128  *              packet buffer. Therefore, at load time, all checks on pointers
2129  *              previously done by the verifier are invalidated and must be
2130  *              performed again, if the helper is used in combination with
2131  *              direct packet access.
2132  *      Return
2133  *              0 on success, or a negative error in case of failure.
2134  *
2135  * int bpf_lwt_seg6_adjust_srh(struct sk_buff *skb, u32 offset, s32 delta)
2136  *      Description
2137  *              Adjust the size allocated to TLVs in the outermost IPv6
2138  *              Segment Routing Header contained in the packet associated to
2139  *              *skb*, at position *offset* by *delta* bytes. Only offsets
2140  *              after the segments are accepted. *delta* can be as well
2141  *              positive (growing) as negative (shrinking).
2142  *
2143  *              A call to this helper is susceptible to change the underlying
2144  *              packet buffer. Therefore, at load time, all checks on pointers
2145  *              previously done by the verifier are invalidated and must be
2146  *              performed again, if the helper is used in combination with
2147  *              direct packet access.
2148  *      Return
2149  *              0 on success, or a negative error in case of failure.
2150  *
2151  * int bpf_lwt_seg6_action(struct sk_buff *skb, u32 action, void *param, u32 param_len)
2152  *      Description
2153  *              Apply an IPv6 Segment Routing action of type *action* to the
2154  *              packet associated to *skb*. Each action takes a parameter
2155  *              contained at address *param*, and of length *param_len* bytes.
2156  *              *action* can be one of:
2157  *
2158  *              **SEG6_LOCAL_ACTION_END_X**
2159  *                      End.X action: Endpoint with Layer-3 cross-connect.
2160  *                      Type of *param*: **struct in6_addr**.
2161  *              **SEG6_LOCAL_ACTION_END_T**
2162  *                      End.T action: Endpoint with specific IPv6 table lookup.
2163  *                      Type of *param*: **int**.
2164  *              **SEG6_LOCAL_ACTION_END_B6**
2165  *                      End.B6 action: Endpoint bound to an SRv6 policy.
2166  *                      Type of *param*: **struct ipv6_sr_hdr**.
2167  *              **SEG6_LOCAL_ACTION_END_B6_ENCAP**
2168  *                      End.B6.Encap action: Endpoint bound to an SRv6
2169  *                      encapsulation policy.
2170  *                      Type of *param*: **struct ipv6_sr_hdr**.
2171  *
2172  *              A call to this helper is susceptible to change the underlying
2173  *              packet buffer. Therefore, at load time, all checks on pointers
2174  *              previously done by the verifier are invalidated and must be
2175  *              performed again, if the helper is used in combination with
2176  *              direct packet access.
2177  *      Return
2178  *              0 on success, or a negative error in case of failure.
2179  *
2180  * int bpf_rc_repeat(void *ctx)
2181  *      Description
2182  *              This helper is used in programs implementing IR decoding, to
2183  *              report a successfully decoded repeat key message. This delays
2184  *              the generation of a key up event for previously generated
2185  *              key down event.
2186  *
2187  *              Some IR protocols like NEC have a special IR message for
2188  *              repeating last button, for when a button is held down.
2189  *
2190  *              The *ctx* should point to the lirc sample as passed into
2191  *              the program.
2192  *
2193  *              This helper is only available is the kernel was compiled with
2194  *              the **CONFIG_BPF_LIRC_MODE2** configuration option set to
2195  *              "**y**".
2196  *      Return
2197  *              0
2198  *
2199  * int bpf_rc_keydown(void *ctx, u32 protocol, u64 scancode, u32 toggle)
2200  *      Description
2201  *              This helper is used in programs implementing IR decoding, to
2202  *              report a successfully decoded key press with *scancode*,
2203  *              *toggle* value in the given *protocol*. The scancode will be
2204  *              translated to a keycode using the rc keymap, and reported as
2205  *              an input key down event. After a period a key up event is
2206  *              generated. This period can be extended by calling either
2207  *              **bpf_rc_keydown**\ () again with the same values, or calling
2208  *              **bpf_rc_repeat**\ ().
2209  *
2210  *              Some protocols include a toggle bit, in case the button was
2211  *              released and pressed again between consecutive scancodes.
2212  *
2213  *              The *ctx* should point to the lirc sample as passed into
2214  *              the program.
2215  *
2216  *              The *protocol* is the decoded protocol number (see
2217  *              **enum rc_proto** for some predefined values).
2218  *
2219  *              This helper is only available is the kernel was compiled with
2220  *              the **CONFIG_BPF_LIRC_MODE2** configuration option set to
2221  *              "**y**".
2222  *      Return
2223  *              0
2224  *
2225  * u64 bpf_skb_cgroup_id(struct sk_buff *skb)
2226  *      Description
2227  *              Return the cgroup v2 id of the socket associated with the *skb*.
2228  *              This is roughly similar to the **bpf_get_cgroup_classid**\ ()
2229  *              helper for cgroup v1 by providing a tag resp. identifier that
2230  *              can be matched on or used for map lookups e.g. to implement
2231  *              policy. The cgroup v2 id of a given path in the hierarchy is
2232  *              exposed in user space through the f_handle API in order to get
2233  *              to the same 64-bit id.
2234  *
2235  *              This helper can be used on TC egress path, but not on ingress,
2236  *              and is available only if the kernel was compiled with the
2237  *              **CONFIG_SOCK_CGROUP_DATA** configuration option.
2238  *      Return
2239  *              The id is returned or 0 in case the id could not be retrieved.
2240  *
2241  * u64 bpf_get_current_cgroup_id(void)
2242  *      Return
2243  *              A 64-bit integer containing the current cgroup id based
2244  *              on the cgroup within which the current task is running.
2245  *
2246  * void *bpf_get_local_storage(void *map, u64 flags)
2247  *      Description
2248  *              Get the pointer to the local storage area.
2249  *              The type and the size of the local storage is defined
2250  *              by the *map* argument.
2251  *              The *flags* meaning is specific for each map type,
2252  *              and has to be 0 for cgroup local storage.
2253  *
2254  *              Depending on the BPF program type, a local storage area
2255  *              can be shared between multiple instances of the BPF program,
2256  *              running simultaneously.
2257  *
2258  *              A user should care about the synchronization by himself.
2259  *              For example, by using the **BPF_STX_XADD** instruction to alter
2260  *              the shared data.
2261  *      Return
2262  *              A pointer to the local storage area.
2263  *
2264  * int bpf_sk_select_reuseport(struct sk_reuseport_md *reuse, struct bpf_map *map, void *key, u64 flags)
2265  *      Description
2266  *              Select a **SO_REUSEPORT** socket from a
2267  *              **BPF_MAP_TYPE_REUSEPORT_ARRAY** *map*.
2268  *              It checks the selected socket is matching the incoming
2269  *              request in the socket buffer.
2270  *      Return
2271  *              0 on success, or a negative error in case of failure.
2272  *
2273  * u64 bpf_skb_ancestor_cgroup_id(struct sk_buff *skb, int ancestor_level)
2274  *      Description
2275  *              Return id of cgroup v2 that is ancestor of cgroup associated
2276  *              with the *skb* at the *ancestor_level*.  The root cgroup is at
2277  *              *ancestor_level* zero and each step down the hierarchy
2278  *              increments the level. If *ancestor_level* == level of cgroup
2279  *              associated with *skb*, then return value will be same as that
2280  *              of **bpf_skb_cgroup_id**\ ().
2281  *
2282  *              The helper is useful to implement policies based on cgroups
2283  *              that are upper in hierarchy than immediate cgroup associated
2284  *              with *skb*.
2285  *
2286  *              The format of returned id and helper limitations are same as in
2287  *              **bpf_skb_cgroup_id**\ ().
2288  *      Return
2289  *              The id is returned or 0 in case the id could not be retrieved.
2290  *
2291  * struct bpf_sock *bpf_sk_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
2292  *      Description
2293  *              Look for TCP socket matching *tuple*, optionally in a child
2294  *              network namespace *netns*. The return value must be checked,
2295  *              and if non-**NULL**, released via **bpf_sk_release**\ ().
2296  *
2297  *              The *ctx* should point to the context of the program, such as
2298  *              the skb or socket (depending on the hook in use). This is used
2299  *              to determine the base network namespace for the lookup.
2300  *
2301  *              *tuple_size* must be one of:
2302  *
2303  *              **sizeof**\ (*tuple*\ **->ipv4**)
2304  *                      Look for an IPv4 socket.
2305  *              **sizeof**\ (*tuple*\ **->ipv6**)
2306  *                      Look for an IPv6 socket.
2307  *
2308  *              If the *netns* is a negative signed 32-bit integer, then the
2309  *              socket lookup table in the netns associated with the *ctx* will
2310  *              will be used. For the TC hooks, this is the netns of the device
2311  *              in the skb. For socket hooks, this is the netns of the socket.
2312  *              If *netns* is any other signed 32-bit value greater than or
2313  *              equal to zero then it specifies the ID of the netns relative to
2314  *              the netns associated with the *ctx*. *netns* values beyond the
2315  *              range of 32-bit integers are reserved for future use.
2316  *
2317  *              All values for *flags* are reserved for future usage, and must
2318  *              be left at zero.
2319  *
2320  *              This helper is available only if the kernel was compiled with
2321  *              **CONFIG_NET** configuration option.
2322  *      Return
2323  *              Pointer to **struct bpf_sock**, or **NULL** in case of failure.
2324  *              For sockets with reuseport option, the **struct bpf_sock**
2325  *              result is from *reuse*\ **->socks**\ [] using the hash of the
2326  *              tuple.
2327  *
2328  * struct bpf_sock *bpf_sk_lookup_udp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
2329  *      Description
2330  *              Look for UDP socket matching *tuple*, optionally in a child
2331  *              network namespace *netns*. The return value must be checked,
2332  *              and if non-**NULL**, released via **bpf_sk_release**\ ().
2333  *
2334  *              The *ctx* should point to the context of the program, such as
2335  *              the skb or socket (depending on the hook in use). This is used
2336  *              to determine the base network namespace for the lookup.
2337  *
2338  *              *tuple_size* must be one of:
2339  *
2340  *              **sizeof**\ (*tuple*\ **->ipv4**)
2341  *                      Look for an IPv4 socket.
2342  *              **sizeof**\ (*tuple*\ **->ipv6**)
2343  *                      Look for an IPv6 socket.
2344  *
2345  *              If the *netns* is a negative signed 32-bit integer, then the
2346  *              socket lookup table in the netns associated with the *ctx* will
2347  *              will be used. For the TC hooks, this is the netns of the device
2348  *              in the skb. For socket hooks, this is the netns of the socket.
2349  *              If *netns* is any other signed 32-bit value greater than or
2350  *              equal to zero then it specifies the ID of the netns relative to
2351  *              the netns associated with the *ctx*. *netns* values beyond the
2352  *              range of 32-bit integers are reserved for future use.
2353  *
2354  *              All values for *flags* are reserved for future usage, and must
2355  *              be left at zero.
2356  *
2357  *              This helper is available only if the kernel was compiled with
2358  *              **CONFIG_NET** configuration option.
2359  *      Return
2360  *              Pointer to **struct bpf_sock**, or **NULL** in case of failure.
2361  *              For sockets with reuseport option, the **struct bpf_sock**
2362  *              result is from *reuse*\ **->socks**\ [] using the hash of the
2363  *              tuple.
2364  *
2365  * int bpf_sk_release(struct bpf_sock *sock)
2366  *      Description
2367  *              Release the reference held by *sock*. *sock* must be a
2368  *              non-**NULL** pointer that was returned from
2369  *              **bpf_sk_lookup_xxx**\ ().
2370  *      Return
2371  *              0 on success, or a negative error in case of failure.
2372  *
2373  * int bpf_map_push_elem(struct bpf_map *map, const void *value, u64 flags)
2374  *      Description
2375  *              Push an element *value* in *map*. *flags* is one of:
2376  *
2377  *              **BPF_EXIST**
2378  *                      If the queue/stack is full, the oldest element is
2379  *                      removed to make room for this.
2380  *      Return
2381  *              0 on success, or a negative error in case of failure.
2382  *
2383  * int bpf_map_pop_elem(struct bpf_map *map, void *value)
2384  *      Description
2385  *              Pop an element from *map*.
2386  *      Return
2387  *              0 on success, or a negative error in case of failure.
2388  *
2389  * int bpf_map_peek_elem(struct bpf_map *map, void *value)
2390  *      Description
2391  *              Get an element from *map* without removing it.
2392  *      Return
2393  *              0 on success, or a negative error in case of failure.
2394  *
2395  * int bpf_msg_push_data(struct sk_buff *skb, u32 start, u32 len, u64 flags)
2396  *      Description
2397  *              For socket policies, insert *len* bytes into *msg* at offset
2398  *              *start*.
2399  *
2400  *              If a program of type **BPF_PROG_TYPE_SK_MSG** is run on a
2401  *              *msg* it may want to insert metadata or options into the *msg*.
2402  *              This can later be read and used by any of the lower layer BPF
2403  *              hooks.
2404  *
2405  *              This helper may fail if under memory pressure (a malloc
2406  *              fails) in these cases BPF programs will get an appropriate
2407  *              error and BPF programs will need to handle them.
2408  *      Return
2409  *              0 on success, or a negative error in case of failure.
2410  *
2411  * int bpf_msg_pop_data(struct sk_msg_buff *msg, u32 start, u32 pop, u64 flags)
2412  *      Description
2413  *              Will remove *pop* bytes from a *msg* starting at byte *start*.
2414  *              This may result in **ENOMEM** errors under certain situations if
2415  *              an allocation and copy are required due to a full ring buffer.
2416  *              However, the helper will try to avoid doing the allocation
2417  *              if possible. Other errors can occur if input parameters are
2418  *              invalid either due to *start* byte not being valid part of *msg*
2419  *              payload and/or *pop* value being to large.
2420  *      Return
2421  *              0 on success, or a negative error in case of failure.
2422  *
2423  * int bpf_rc_pointer_rel(void *ctx, s32 rel_x, s32 rel_y)
2424  *      Description
2425  *              This helper is used in programs implementing IR decoding, to
2426  *              report a successfully decoded pointer movement.
2427  *
2428  *              The *ctx* should point to the lirc sample as passed into
2429  *              the program.
2430  *
2431  *              This helper is only available is the kernel was compiled with
2432  *              the **CONFIG_BPF_LIRC_MODE2** configuration option set to
2433  *              "**y**".
2434  *      Return
2435  *              0
2436  *
2437  * int bpf_spin_lock(struct bpf_spin_lock *lock)
2438  *      Description
2439  *              Acquire a spinlock represented by the pointer *lock*, which is
2440  *              stored as part of a value of a map. Taking the lock allows to
2441  *              safely update the rest of the fields in that value. The
2442  *              spinlock can (and must) later be released with a call to
2443  *              **bpf_spin_unlock**\ (\ *lock*\ ).
2444  *
2445  *              Spinlocks in BPF programs come with a number of restrictions
2446  *              and constraints:
2447  *
2448  *              * **bpf_spin_lock** objects are only allowed inside maps of
2449  *                types **BPF_MAP_TYPE_HASH** and **BPF_MAP_TYPE_ARRAY** (this
2450  *                list could be extended in the future).
2451  *              * BTF description of the map is mandatory.
2452  *              * The BPF program can take ONE lock at a time, since taking two
2453  *                or more could cause dead locks.
2454  *              * Only one **struct bpf_spin_lock** is allowed per map element.
2455  *              * When the lock is taken, calls (either BPF to BPF or helpers)
2456  *                are not allowed.
2457  *              * The **BPF_LD_ABS** and **BPF_LD_IND** instructions are not
2458  *                allowed inside a spinlock-ed region.
2459  *              * The BPF program MUST call **bpf_spin_unlock**\ () to release
2460  *                the lock, on all execution paths, before it returns.
2461  *              * The BPF program can access **struct bpf_spin_lock** only via
2462  *                the **bpf_spin_lock**\ () and **bpf_spin_unlock**\ ()
2463  *                helpers. Loading or storing data into the **struct
2464  *                bpf_spin_lock** *lock*\ **;** field of a map is not allowed.
2465  *              * To use the **bpf_spin_lock**\ () helper, the BTF description
2466  *                of the map value must be a struct and have **struct
2467  *                bpf_spin_lock** *anyname*\ **;** field at the top level.
2468  *                Nested lock inside another struct is not allowed.
2469  *              * The **struct bpf_spin_lock** *lock* field in a map value must
2470  *                be aligned on a multiple of 4 bytes in that value.
2471  *              * Syscall with command **BPF_MAP_LOOKUP_ELEM** does not copy
2472  *                the **bpf_spin_lock** field to user space.
2473  *              * Syscall with command **BPF_MAP_UPDATE_ELEM**, or update from
2474  *                a BPF program, do not update the **bpf_spin_lock** field.
2475  *              * **bpf_spin_lock** cannot be on the stack or inside a
2476  *                networking packet (it can only be inside of a map values).
2477  *              * **bpf_spin_lock** is available to root only.
2478  *              * Tracing programs and socket filter programs cannot use
2479  *                **bpf_spin_lock**\ () due to insufficient preemption checks
2480  *                (but this may change in the future).
2481  *              * **bpf_spin_lock** is not allowed in inner maps of map-in-map.
2482  *      Return
2483  *              0
2484  *
2485  * int bpf_spin_unlock(struct bpf_spin_lock *lock)
2486  *      Description
2487  *              Release the *lock* previously locked by a call to
2488  *              **bpf_spin_lock**\ (\ *lock*\ ).
2489  *      Return
2490  *              0
2491  *
2492  * struct bpf_sock *bpf_sk_fullsock(struct bpf_sock *sk)
2493  *      Description
2494  *              This helper gets a **struct bpf_sock** pointer such
2495  *              that all the fields in this **bpf_sock** can be accessed.
2496  *      Return
2497  *              A **struct bpf_sock** pointer on success, or **NULL** in
2498  *              case of failure.
2499  *
2500  * struct bpf_tcp_sock *bpf_tcp_sock(struct bpf_sock *sk)
2501  *      Description
2502  *              This helper gets a **struct bpf_tcp_sock** pointer from a
2503  *              **struct bpf_sock** pointer.
2504  *      Return
2505  *              A **struct bpf_tcp_sock** pointer on success, or **NULL** in
2506  *              case of failure.
2507  *
2508  * int bpf_skb_ecn_set_ce(struct sk_buf *skb)
2509  *      Description
2510  *              Set ECN (Explicit Congestion Notification) field of IP header
2511  *              to **CE** (Congestion Encountered) if current value is **ECT**
2512  *              (ECN Capable Transport). Otherwise, do nothing. Works with IPv6
2513  *              and IPv4.
2514  *      Return
2515  *              1 if the **CE** flag is set (either by the current helper call
2516  *              or because it was already present), 0 if it is not set.
2517  *
2518  * struct bpf_sock *bpf_get_listener_sock(struct bpf_sock *sk)
2519  *      Description
2520  *              Return a **struct bpf_sock** pointer in **TCP_LISTEN** state.
2521  *              **bpf_sk_release**\ () is unnecessary and not allowed.
2522  *      Return
2523  *              A **struct bpf_sock** pointer on success, or **NULL** in
2524  *              case of failure.
2525  *
2526  * struct bpf_sock *bpf_skc_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
2527  *      Description
2528  *              Look for TCP socket matching *tuple*, optionally in a child
2529  *              network namespace *netns*. The return value must be checked,
2530  *              and if non-**NULL**, released via **bpf_sk_release**\ ().
2531  *
2532  *              This function is identical to **bpf_sk_lookup_tcp**\ (), except
2533  *              that it also returns timewait or request sockets. Use
2534  *              **bpf_sk_fullsock**\ () or **bpf_tcp_sock**\ () to access the
2535  *              full structure.
2536  *
2537  *              This helper is available only if the kernel was compiled with
2538  *              **CONFIG_NET** configuration option.
2539  *      Return
2540  *              Pointer to **struct bpf_sock**, or **NULL** in case of failure.
2541  *              For sockets with reuseport option, the **struct bpf_sock**
2542  *              result is from *reuse*\ **->socks**\ [] using the hash of the
2543  *              tuple.
2544  *
2545  * int bpf_tcp_check_syncookie(struct bpf_sock *sk, void *iph, u32 iph_len, struct tcphdr *th, u32 th_len)
2546  *      Description
2547  *              Check whether *iph* and *th* contain a valid SYN cookie ACK for
2548  *              the listening socket in *sk*.
2549  *
2550  *              *iph* points to the start of the IPv4 or IPv6 header, while
2551  *              *iph_len* contains **sizeof**\ (**struct iphdr**) or
2552  *              **sizeof**\ (**struct ip6hdr**).
2553  *
2554  *              *th* points to the start of the TCP header, while *th_len*
2555  *              contains **sizeof**\ (**struct tcphdr**).
2556  *
2557  *      Return
2558  *              0 if *iph* and *th* are a valid SYN cookie ACK, or a negative
2559  *              error otherwise.
2560  *
2561  * int bpf_sysctl_get_name(struct bpf_sysctl *ctx, char *buf, size_t buf_len, u64 flags)
2562  *      Description
2563  *              Get name of sysctl in /proc/sys/ and copy it into provided by
2564  *              program buffer *buf* of size *buf_len*.
2565  *
2566  *              The buffer is always NUL terminated, unless it's zero-sized.
2567  *
2568  *              If *flags* is zero, full name (e.g. "net/ipv4/tcp_mem") is
2569  *              copied. Use **BPF_F_SYSCTL_BASE_NAME** flag to copy base name
2570  *              only (e.g. "tcp_mem").
2571  *      Return
2572  *              Number of character copied (not including the trailing NUL).
2573  *
2574  *              **-E2BIG** if the buffer wasn't big enough (*buf* will contain
2575  *              truncated name in this case).
2576  *
2577  * int bpf_sysctl_get_current_value(struct bpf_sysctl *ctx, char *buf, size_t buf_len)
2578  *      Description
2579  *              Get current value of sysctl as it is presented in /proc/sys
2580  *              (incl. newline, etc), and copy it as a string into provided
2581  *              by program buffer *buf* of size *buf_len*.
2582  *
2583  *              The whole value is copied, no matter what file position user
2584  *              space issued e.g. sys_read at.
2585  *
2586  *              The buffer is always NUL terminated, unless it's zero-sized.
2587  *      Return
2588  *              Number of character copied (not including the trailing NUL).
2589  *
2590  *              **-E2BIG** if the buffer wasn't big enough (*buf* will contain
2591  *              truncated name in this case).
2592  *
2593  *              **-EINVAL** if current value was unavailable, e.g. because
2594  *              sysctl is uninitialized and read returns -EIO for it.
2595  *
2596  * int bpf_sysctl_get_new_value(struct bpf_sysctl *ctx, char *buf, size_t buf_len)
2597  *      Description
2598  *              Get new value being written by user space to sysctl (before
2599  *              the actual write happens) and copy it as a string into
2600  *              provided by program buffer *buf* of size *buf_len*.
2601  *
2602  *              User space may write new value at file position > 0.
2603  *
2604  *              The buffer is always NUL terminated, unless it's zero-sized.
2605  *      Return
2606  *              Number of character copied (not including the trailing NUL).
2607  *
2608  *              **-E2BIG** if the buffer wasn't big enough (*buf* will contain
2609  *              truncated name in this case).
2610  *
2611  *              **-EINVAL** if sysctl is being read.
2612  *
2613  * int bpf_sysctl_set_new_value(struct bpf_sysctl *ctx, const char *buf, size_t buf_len)
2614  *      Description
2615  *              Override new value being written by user space to sysctl with
2616  *              value provided by program in buffer *buf* of size *buf_len*.
2617  *
2618  *              *buf* should contain a string in same form as provided by user
2619  *              space on sysctl write.
2620  *
2621  *              User space may write new value at file position > 0. To override
2622  *              the whole sysctl value file position should be set to zero.
2623  *      Return
2624  *              0 on success.
2625  *
2626  *              **-E2BIG** if the *buf_len* is too big.
2627  *
2628  *              **-EINVAL** if sysctl is being read.
2629  *
2630  * int bpf_strtol(const char *buf, size_t buf_len, u64 flags, long *res)
2631  *      Description
2632  *              Convert the initial part of the string from buffer *buf* of
2633  *              size *buf_len* to a long integer according to the given base
2634  *              and save the result in *res*.
2635  *
2636  *              The string may begin with an arbitrary amount of white space
2637  *              (as determined by **isspace**\ (3)) followed by a single
2638  *              optional '**-**' sign.
2639  *
2640  *              Five least significant bits of *flags* encode base, other bits
2641  *              are currently unused.
2642  *
2643  *              Base must be either 8, 10, 16 or 0 to detect it automatically
2644  *              similar to user space **strtol**\ (3).
2645  *      Return
2646  *              Number of characters consumed on success. Must be positive but
2647  *              no more than *buf_len*.
2648  *
2649  *              **-EINVAL** if no valid digits were found or unsupported base
2650  *              was provided.
2651  *
2652  *              **-ERANGE** if resulting value was out of range.
2653  *
2654  * int bpf_strtoul(const char *buf, size_t buf_len, u64 flags, unsigned long *res)
2655  *      Description
2656  *              Convert the initial part of the string from buffer *buf* of
2657  *              size *buf_len* to an unsigned long integer according to the
2658  *              given base and save the result in *res*.
2659  *
2660  *              The string may begin with an arbitrary amount of white space
2661  *              (as determined by **isspace**\ (3)).
2662  *
2663  *              Five least significant bits of *flags* encode base, other bits
2664  *              are currently unused.
2665  *
2666  *              Base must be either 8, 10, 16 or 0 to detect it automatically
2667  *              similar to user space **strtoul**\ (3).
2668  *      Return
2669  *              Number of characters consumed on success. Must be positive but
2670  *              no more than *buf_len*.
2671  *
2672  *              **-EINVAL** if no valid digits were found or unsupported base
2673  *              was provided.
2674  *
2675  *              **-ERANGE** if resulting value was out of range.
2676  *
2677  * void *bpf_sk_storage_get(struct bpf_map *map, struct bpf_sock *sk, void *value, u64 flags)
2678  *      Description
2679  *              Get a bpf-local-storage from a *sk*.
2680  *
2681  *              Logically, it could be thought of getting the value from
2682  *              a *map* with *sk* as the **key**.  From this
2683  *              perspective,  the usage is not much different from
2684  *              **bpf_map_lookup_elem**\ (*map*, **&**\ *sk*) except this
2685  *              helper enforces the key must be a full socket and the map must
2686  *              be a **BPF_MAP_TYPE_SK_STORAGE** also.
2687  *
2688  *              Underneath, the value is stored locally at *sk* instead of
2689  *              the *map*.  The *map* is used as the bpf-local-storage
2690  *              "type". The bpf-local-storage "type" (i.e. the *map*) is
2691  *              searched against all bpf-local-storages residing at *sk*.
2692  *
2693  *              An optional *flags* (**BPF_SK_STORAGE_GET_F_CREATE**) can be
2694  *              used such that a new bpf-local-storage will be
2695  *              created if one does not exist.  *value* can be used
2696  *              together with **BPF_SK_STORAGE_GET_F_CREATE** to specify
2697  *              the initial value of a bpf-local-storage.  If *value* is
2698  *              **NULL**, the new bpf-local-storage will be zero initialized.
2699  *      Return
2700  *              A bpf-local-storage pointer is returned on success.
2701  *
2702  *              **NULL** if not found or there was an error in adding
2703  *              a new bpf-local-storage.
2704  *
2705  * int bpf_sk_storage_delete(struct bpf_map *map, struct bpf_sock *sk)
2706  *      Description
2707  *              Delete a bpf-local-storage from a *sk*.
2708  *      Return
2709  *              0 on success.
2710  *
2711  *              **-ENOENT** if the bpf-local-storage cannot be found.
2712  *
2713  * int bpf_send_signal(u32 sig)
2714  *      Description
2715  *              Send signal *sig* to the current task.
2716  *      Return
2717  *              0 on success or successfully queued.
2718  *
2719  *              **-EBUSY** if work queue under nmi is full.
2720  *
2721  *              **-EINVAL** if *sig* is invalid.
2722  *
2723  *              **-EPERM** if no permission to send the *sig*.
2724  *
2725  *              **-EAGAIN** if bpf program can try again.
2726  *
2727  * s64 bpf_tcp_gen_syncookie(struct bpf_sock *sk, void *iph, u32 iph_len, struct tcphdr *th, u32 th_len)
2728  *      Description
2729  *              Try to issue a SYN cookie for the packet with corresponding
2730  *              IP/TCP headers, *iph* and *th*, on the listening socket in *sk*.
2731  *
2732  *              *iph* points to the start of the IPv4 or IPv6 header, while
2733  *              *iph_len* contains **sizeof**\ (**struct iphdr**) or
2734  *              **sizeof**\ (**struct ip6hdr**).
2735  *
2736  *              *th* points to the start of the TCP header, while *th_len*
2737  *              contains the length of the TCP header.
2738  *
2739  *      Return
2740  *              On success, lower 32 bits hold the generated SYN cookie in
2741  *              followed by 16 bits which hold the MSS value for that cookie,
2742  *              and the top 16 bits are unused.
2743  *
2744  *              On failure, the returned value is one of the following:
2745  *
2746  *              **-EINVAL** SYN cookie cannot be issued due to error
2747  *
2748  *              **-ENOENT** SYN cookie should not be issued (no SYN flood)
2749  *
2750  *              **-EOPNOTSUPP** kernel configuration does not enable SYN cookies
2751  *
2752  *              **-EPROTONOSUPPORT** IP packet version is not 4 or 6
2753  */
2754 #define __BPF_FUNC_MAPPER(FN)           \
2755         FN(unspec),                     \
2756         FN(map_lookup_elem),            \
2757         FN(map_update_elem),            \
2758         FN(map_delete_elem),            \
2759         FN(probe_read),                 \
2760         FN(ktime_get_ns),               \
2761         FN(trace_printk),               \
2762         FN(get_prandom_u32),            \
2763         FN(get_smp_processor_id),       \
2764         FN(skb_store_bytes),            \
2765         FN(l3_csum_replace),            \
2766         FN(l4_csum_replace),            \
2767         FN(tail_call),                  \
2768         FN(clone_redirect),             \
2769         FN(get_current_pid_tgid),       \
2770         FN(get_current_uid_gid),        \
2771         FN(get_current_comm),           \
2772         FN(get_cgroup_classid),         \
2773         FN(skb_vlan_push),              \
2774         FN(skb_vlan_pop),               \
2775         FN(skb_get_tunnel_key),         \
2776         FN(skb_set_tunnel_key),         \
2777         FN(perf_event_read),            \
2778         FN(redirect),                   \
2779         FN(get_route_realm),            \
2780         FN(perf_event_output),          \
2781         FN(skb_load_bytes),             \
2782         FN(get_stackid),                \
2783         FN(csum_diff),                  \
2784         FN(skb_get_tunnel_opt),         \
2785         FN(skb_set_tunnel_opt),         \
2786         FN(skb_change_proto),           \
2787         FN(skb_change_type),            \
2788         FN(skb_under_cgroup),           \
2789         FN(get_hash_recalc),            \
2790         FN(get_current_task),           \
2791         FN(probe_write_user),           \
2792         FN(current_task_under_cgroup),  \
2793         FN(skb_change_tail),            \
2794         FN(skb_pull_data),              \
2795         FN(csum_update),                \
2796         FN(set_hash_invalid),           \
2797         FN(get_numa_node_id),           \
2798         FN(skb_change_head),            \
2799         FN(xdp_adjust_head),            \
2800         FN(probe_read_str),             \
2801         FN(get_socket_cookie),          \
2802         FN(get_socket_uid),             \
2803         FN(set_hash),                   \
2804         FN(setsockopt),                 \
2805         FN(skb_adjust_room),            \
2806         FN(redirect_map),               \
2807         FN(sk_redirect_map),            \
2808         FN(sock_map_update),            \
2809         FN(xdp_adjust_meta),            \
2810         FN(perf_event_read_value),      \
2811         FN(perf_prog_read_value),       \
2812         FN(getsockopt),                 \
2813         FN(override_return),            \
2814         FN(sock_ops_cb_flags_set),      \
2815         FN(msg_redirect_map),           \
2816         FN(msg_apply_bytes),            \
2817         FN(msg_cork_bytes),             \
2818         FN(msg_pull_data),              \
2819         FN(bind),                       \
2820         FN(xdp_adjust_tail),            \
2821         FN(skb_get_xfrm_state),         \
2822         FN(get_stack),                  \
2823         FN(skb_load_bytes_relative),    \
2824         FN(fib_lookup),                 \
2825         FN(sock_hash_update),           \
2826         FN(msg_redirect_hash),          \
2827         FN(sk_redirect_hash),           \
2828         FN(lwt_push_encap),             \
2829         FN(lwt_seg6_store_bytes),       \
2830         FN(lwt_seg6_adjust_srh),        \
2831         FN(lwt_seg6_action),            \
2832         FN(rc_repeat),                  \
2833         FN(rc_keydown),                 \
2834         FN(skb_cgroup_id),              \
2835         FN(get_current_cgroup_id),      \
2836         FN(get_local_storage),          \
2837         FN(sk_select_reuseport),        \
2838         FN(skb_ancestor_cgroup_id),     \
2839         FN(sk_lookup_tcp),              \
2840         FN(sk_lookup_udp),              \
2841         FN(sk_release),                 \
2842         FN(map_push_elem),              \
2843         FN(map_pop_elem),               \
2844         FN(map_peek_elem),              \
2845         FN(msg_push_data),              \
2846         FN(msg_pop_data),               \
2847         FN(rc_pointer_rel),             \
2848         FN(spin_lock),                  \
2849         FN(spin_unlock),                \
2850         FN(sk_fullsock),                \
2851         FN(tcp_sock),                   \
2852         FN(skb_ecn_set_ce),             \
2853         FN(get_listener_sock),          \
2854         FN(skc_lookup_tcp),             \
2855         FN(tcp_check_syncookie),        \
2856         FN(sysctl_get_name),            \
2857         FN(sysctl_get_current_value),   \
2858         FN(sysctl_get_new_value),       \
2859         FN(sysctl_set_new_value),       \
2860         FN(strtol),                     \
2861         FN(strtoul),                    \
2862         FN(sk_storage_get),             \
2863         FN(sk_storage_delete),          \
2864         FN(send_signal),                \
2865         FN(tcp_gen_syncookie),
2866 
2867 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
2868  * function eBPF program intends to call
2869  */
2870 #define __BPF_ENUM_FN(x) BPF_FUNC_ ## x
2871 enum bpf_func_id {
2872         __BPF_FUNC_MAPPER(__BPF_ENUM_FN)
2873         __BPF_FUNC_MAX_ID,
2874 };
2875 #undef __BPF_ENUM_FN
2876 
2877 /* All flags used by eBPF helper functions, placed here. */
2878 
2879 /* BPF_FUNC_skb_store_bytes flags. */
2880 #define BPF_F_RECOMPUTE_CSUM            (1ULL << 0)
2881 #define BPF_F_INVALIDATE_HASH           (1ULL << 1)
2882 
2883 /* BPF_FUNC_l3_csum_replace and BPF_FUNC_l4_csum_replace flags.
2884  * First 4 bits are for passing the header field size.
2885  */
2886 #define BPF_F_HDR_FIELD_MASK            0xfULL
2887 
2888 /* BPF_FUNC_l4_csum_replace flags. */
2889 #define BPF_F_PSEUDO_HDR                (1ULL << 4)
2890 #define BPF_F_MARK_MANGLED_0            (1ULL << 5)
2891 #define BPF_F_MARK_ENFORCE              (1ULL << 6)
2892 
2893 /* BPF_FUNC_clone_redirect and BPF_FUNC_redirect flags. */
2894 #define BPF_F_INGRESS                   (1ULL << 0)
2895 
2896 /* BPF_FUNC_skb_set_tunnel_key and BPF_FUNC_skb_get_tunnel_key flags. */
2897 #define BPF_F_TUNINFO_IPV6              (1ULL << 0)
2898 
2899 /* flags for both BPF_FUNC_get_stackid and BPF_FUNC_get_stack. */
2900 #define BPF_F_SKIP_FIELD_MASK           0xffULL
2901 #define BPF_F_USER_STACK                (1ULL << 8)
2902 /* flags used by BPF_FUNC_get_stackid only. */
2903 #define BPF_F_FAST_STACK_CMP            (1ULL << 9)
2904 #define BPF_F_REUSE_STACKID             (1ULL << 10)
2905 /* flags used by BPF_FUNC_get_stack only. */
2906 #define BPF_F_USER_BUILD_ID             (1ULL << 11)
2907 
2908 /* BPF_FUNC_skb_set_tunnel_key flags. */
2909 #define BPF_F_ZERO_CSUM_TX              (1ULL << 1)
2910 #define BPF_F_DONT_FRAGMENT             (1ULL << 2)
2911 #define BPF_F_SEQ_NUMBER                (1ULL << 3)
2912 
2913 /* BPF_FUNC_perf_event_output, BPF_FUNC_perf_event_read and
2914  * BPF_FUNC_perf_event_read_value flags.
2915  */
2916 #define BPF_F_INDEX_MASK                0xffffffffULL
2917 #define BPF_F_CURRENT_CPU               BPF_F_INDEX_MASK
2918 /* BPF_FUNC_perf_event_output for sk_buff input context. */
2919 #define BPF_F_CTXLEN_MASK               (0xfffffULL << 32)
2920 
2921 /* Current network namespace */
2922 #define BPF_F_CURRENT_NETNS             (-1L)
2923 
2924 /* BPF_FUNC_skb_adjust_room flags. */
2925 #define BPF_F_ADJ_ROOM_FIXED_GSO        (1ULL << 0)
2926 
2927 #define BPF_ADJ_ROOM_ENCAP_L2_MASK      0xff
2928 #define BPF_ADJ_ROOM_ENCAP_L2_SHIFT     56
2929 
2930 #define BPF_F_ADJ_ROOM_ENCAP_L3_IPV4    (1ULL << 1)
2931 #define BPF_F_ADJ_ROOM_ENCAP_L3_IPV6    (1ULL << 2)
2932 #define BPF_F_ADJ_ROOM_ENCAP_L4_GRE     (1ULL << 3)
2933 #define BPF_F_ADJ_ROOM_ENCAP_L4_UDP     (1ULL << 4)
2934 #define BPF_F_ADJ_ROOM_ENCAP_L2(len)    (((__u64)len & \
2935                                           BPF_ADJ_ROOM_ENCAP_L2_MASK) \
2936                                          << BPF_ADJ_ROOM_ENCAP_L2_SHIFT)
2937 
2938 /* BPF_FUNC_sysctl_get_name flags. */
2939 #define BPF_F_SYSCTL_BASE_NAME          (1ULL << 0)
2940 
2941 /* BPF_FUNC_sk_storage_get flags */
2942 #define BPF_SK_STORAGE_GET_F_CREATE     (1ULL << 0)
2943 
2944 /* Mode for BPF_FUNC_skb_adjust_room helper. */
2945 enum bpf_adj_room_mode {
2946         BPF_ADJ_ROOM_NET,
2947         BPF_ADJ_ROOM_MAC,
2948 };
2949 
2950 /* Mode for BPF_FUNC_skb_load_bytes_relative helper. */
2951 enum bpf_hdr_start_off {
2952         BPF_HDR_START_MAC,
2953         BPF_HDR_START_NET,
2954 };
2955 
2956 /* Encapsulation type for BPF_FUNC_lwt_push_encap helper. */
2957 enum bpf_lwt_encap_mode {
2958         BPF_LWT_ENCAP_SEG6,
2959         BPF_LWT_ENCAP_SEG6_INLINE,
2960         BPF_LWT_ENCAP_IP,
2961 };
2962 
2963 #define __bpf_md_ptr(type, name)        \
2964 union {                                 \
2965         type name;                      \
2966         __u64 :64;                      \
2967 } __attribute__((aligned(8)))
2968 
2969 /* user accessible mirror of in-kernel sk_buff.
2970  * new fields can only be added to the end of this structure
2971  */
2972 struct __sk_buff {
2973         __u32 len;
2974         __u32 pkt_type;
2975         __u32 mark;
2976         __u32 queue_mapping;
2977         __u32 protocol;
2978         __u32 vlan_present;
2979         __u32 vlan_tci;
2980         __u32 vlan_proto;
2981         __u32 priority;
2982         __u32 ingress_ifindex;
2983         __u32 ifindex;
2984         __u32 tc_index;
2985         __u32 cb[5];
2986         __u32 hash;
2987         __u32 tc_classid;
2988         __u32 data;
2989         __u32 data_end;
2990         __u32 napi_id;
2991 
2992         /* Accessed by BPF_PROG_TYPE_sk_skb types from here to ... */
2993         __u32 family;
2994         __u32 remote_ip4;       /* Stored in network byte order */
2995         __u32 local_ip4;        /* Stored in network byte order */
2996         __u32 remote_ip6[4];    /* Stored in network byte order */
2997         __u32 local_ip6[4];     /* Stored in network byte order */
2998         __u32 remote_port;      /* Stored in network byte order */
2999         __u32 local_port;       /* stored in host byte order */
3000         /* ... here. */
3001 
3002         __u32 data_meta;
3003         __bpf_md_ptr(struct bpf_flow_keys *, flow_keys);
3004         __u64 tstamp;
3005         __u32 wire_len;
3006         __u32 gso_segs;
3007         __bpf_md_ptr(struct bpf_sock *, sk);
3008 };
3009 
3010 struct bpf_tunnel_key {
3011         __u32 tunnel_id;
3012         union {
3013                 __u32 remote_ipv4;
3014                 __u32 remote_ipv6[4];
3015         };
3016         __u8 tunnel_tos;
3017         __u8 tunnel_ttl;
3018         __u16 tunnel_ext;       /* Padding, future use. */
3019         __u32 tunnel_label;
3020 };
3021 
3022 /* user accessible mirror of in-kernel xfrm_state.
3023  * new fields can only be added to the end of this structure
3024  */
3025 struct bpf_xfrm_state {
3026         __u32 reqid;
3027         __u32 spi;      /* Stored in network byte order */
3028         __u16 family;
3029         __u16 ext;      /* Padding, future use. */
3030         union {
3031                 __u32 remote_ipv4;      /* Stored in network byte order */
3032                 __u32 remote_ipv6[4];   /* Stored in network byte order */
3033         };
3034 };
3035 
3036 /* Generic BPF return codes which all BPF program types may support.
3037  * The values are binary compatible with their TC_ACT_* counter-part to
3038  * provide backwards compatibility with existing SCHED_CLS and SCHED_ACT
3039  * programs.
3040  *
3041  * XDP is handled seprately, see XDP_*.
3042  */
3043 enum bpf_ret_code {
3044         BPF_OK = 0,
3045         /* 1 reserved */
3046         BPF_DROP = 2,
3047         /* 3-6 reserved */
3048         BPF_REDIRECT = 7,
3049         /* >127 are reserved for prog type specific return codes.
3050          *
3051          * BPF_LWT_REROUTE: used by BPF_PROG_TYPE_LWT_IN and
3052          *    BPF_PROG_TYPE_LWT_XMIT to indicate that skb had been
3053          *    changed and should be routed based on its new L3 header.
3054          *    (This is an L3 redirect, as opposed to L2 redirect
3055          *    represented by BPF_REDIRECT above).
3056          */
3057         BPF_LWT_REROUTE = 128,
3058 };
3059 
3060 struct bpf_sock {
3061         __u32 bound_dev_if;
3062         __u32 family;
3063         __u32 type;
3064         __u32 protocol;
3065         __u32 mark;
3066         __u32 priority;
3067         /* IP address also allows 1 and 2 bytes access */
3068         __u32 src_ip4;
3069         __u32 src_ip6[4];
3070         __u32 src_port;         /* host byte order */
3071         __u32 dst_port;         /* network byte order */
3072         __u32 dst_ip4;
3073         __u32 dst_ip6[4];
3074         __u32 state;
3075 };
3076 
3077 struct bpf_tcp_sock {
3078         __u32 snd_cwnd;         /* Sending congestion window            */
3079         __u32 srtt_us;          /* smoothed round trip time << 3 in usecs */
3080         __u32 rtt_min;
3081         __u32 snd_ssthresh;     /* Slow start size threshold            */
3082         __u32 rcv_nxt;          /* What we want to receive next         */
3083         __u32 snd_nxt;          /* Next sequence we send                */
3084         __u32 snd_una;          /* First byte we want an ack for        */
3085         __u32 mss_cache;        /* Cached effective mss, not including SACKS */
3086         __u32 ecn_flags;        /* ECN status bits.                     */
3087         __u32 rate_delivered;   /* saved rate sample: packets delivered */
3088         __u32 rate_interval_us; /* saved rate sample: time elapsed */
3089         __u32 packets_out;      /* Packets which are "in flight"        */
3090         __u32 retrans_out;      /* Retransmitted packets out            */
3091         __u32 total_retrans;    /* Total retransmits for entire connection */
3092         __u32 segs_in;          /* RFC4898 tcpEStatsPerfSegsIn
3093                                  * total number of segments in.
3094                                  */
3095         __u32 data_segs_in;     /* RFC4898 tcpEStatsPerfDataSegsIn
3096                                  * total number of data segments in.
3097                                  */
3098         __u32 segs_out;         /* RFC4898 tcpEStatsPerfSegsOut
3099                                  * The total number of segments sent.
3100                                  */
3101         __u32 data_segs_out;    /* RFC4898 tcpEStatsPerfDataSegsOut
3102                                  * total number of data segments sent.
3103                                  */
3104         __u32 lost_out;         /* Lost packets                 */
3105         __u32 sacked_out;       /* SACK'd packets                       */
3106         __u64 bytes_received;   /* RFC4898 tcpEStatsAppHCThruOctetsReceived
3107                                  * sum(delta(rcv_nxt)), or how many bytes
3108                                  * were acked.
3109                                  */
3110         __u64 bytes_acked;      /* RFC4898 tcpEStatsAppHCThruOctetsAcked
3111                                  * sum(delta(snd_una)), or how many bytes
3112                                  * were acked.
3113                                  */
3114         __u32 dsack_dups;       /* RFC4898 tcpEStatsStackDSACKDups
3115                                  * total number of DSACK blocks received
3116                                  */
3117         __u32 delivered;        /* Total data packets delivered incl. rexmits */
3118         __u32 delivered_ce;     /* Like the above but only ECE marked packets */
3119         __u32 icsk_retransmits; /* Number of unrecovered [RTO] timeouts */
3120 };
3121 
3122 struct bpf_sock_tuple {
3123         union {
3124                 struct {
3125                         __be32 saddr;
3126                         __be32 daddr;
3127                         __be16 sport;
3128                         __be16 dport;
3129                 } ipv4;
3130                 struct {
3131                         __be32 saddr[4];
3132                         __be32 daddr[4];
3133                         __be16 sport;
3134                         __be16 dport;
3135                 } ipv6;
3136         };
3137 };
3138 
3139 struct bpf_xdp_sock {
3140         __u32 queue_id;
3141 };
3142 
3143 #define XDP_PACKET_HEADROOM 256
3144 
3145 /* User return codes for XDP prog type.
3146  * A valid XDP program must return one of these defined values. All other
3147  * return codes are reserved for future use. Unknown return codes will
3148  * result in packet drops and a warning via bpf_warn_invalid_xdp_action().
3149  */
3150 enum xdp_action {
3151         XDP_ABORTED = 0,
3152         XDP_DROP,
3153         XDP_PASS,
3154         XDP_TX,
3155         XDP_REDIRECT,
3156 };
3157 
3158 /* user accessible metadata for XDP packet hook
3159  * new fields must be added to the end of this structure
3160  */
3161 struct xdp_md {
3162         __u32 data;
3163         __u32 data_end;
3164         __u32 data_meta;
3165         /* Below access go through struct xdp_rxq_info */
3166         __u32 ingress_ifindex; /* rxq->dev->ifindex */
3167         __u32 rx_queue_index;  /* rxq->queue_index  */
3168 };
3169 
3170 enum sk_action {
3171         SK_DROP = 0,
3172         SK_PASS,
3173 };
3174 
3175 /* user accessible metadata for SK_MSG packet hook, new fields must
3176  * be added to the end of this structure
3177  */
3178 struct sk_msg_md {
3179         __bpf_md_ptr(void *, data);
3180         __bpf_md_ptr(void *, data_end);
3181 
3182         __u32 family;
3183         __u32 remote_ip4;       /* Stored in network byte order */
3184         __u32 local_ip4;        /* Stored in network byte order */
3185         __u32 remote_ip6[4];    /* Stored in network byte order */
3186         __u32 local_ip6[4];     /* Stored in network byte order */
3187         __u32 remote_port;      /* Stored in network byte order */
3188         __u32 local_port;       /* stored in host byte order */
3189         __u32 size;             /* Total size of sk_msg */
3190 };
3191 
3192 struct sk_reuseport_md {
3193         /*
3194          * Start of directly accessible data. It begins from
3195          * the tcp/udp header.
3196          */
3197         __bpf_md_ptr(void *, data);
3198         /* End of directly accessible data */
3199         __bpf_md_ptr(void *, data_end);
3200         /*
3201          * Total length of packet (starting from the tcp/udp header).
3202          * Note that the directly accessible bytes (data_end - data)
3203          * could be less than this "len".  Those bytes could be
3204          * indirectly read by a helper "bpf_skb_load_bytes()".
3205          */
3206         __u32 len;
3207         /*
3208          * Eth protocol in the mac header (network byte order). e.g.
3209          * ETH_P_IP(0x0800) and ETH_P_IPV6(0x86DD)
3210          */
3211         __u32 eth_protocol;
3212         __u32 ip_protocol;      /* IP protocol. e.g. IPPROTO_TCP, IPPROTO_UDP */
3213         __u32 bind_inany;       /* Is sock bound to an INANY address? */
3214         __u32 hash;             /* A hash of the packet 4 tuples */
3215 };
3216 
3217 #define BPF_TAG_SIZE    8
3218 
3219 struct bpf_prog_info {
3220         __u32 type;
3221         __u32 id;
3222         __u8  tag[BPF_TAG_SIZE];
3223         __u32 jited_prog_len;
3224         __u32 xlated_prog_len;
3225         __aligned_u64 jited_prog_insns;
3226         __aligned_u64 xlated_prog_insns;
3227         __u64 load_time;        /* ns since boottime */
3228         __u32 created_by_uid;
3229         __u32 nr_map_ids;
3230         __aligned_u64 map_ids;
3231         char name[BPF_OBJ_NAME_LEN];
3232         __u32 ifindex;
3233         __u32 gpl_compatible:1;
3234         __u32 :31; /* alignment pad */
3235         __u64 netns_dev;
3236         __u64 netns_ino;
3237         __u32 nr_jited_ksyms;
3238         __u32 nr_jited_func_lens;
3239         __aligned_u64 jited_ksyms;
3240         __aligned_u64 jited_func_lens;
3241         __u32 btf_id;
3242         __u32 func_info_rec_size;
3243         __aligned_u64 func_info;
3244         __u32 nr_func_info;
3245         __u32 nr_line_info;
3246         __aligned_u64 line_info;
3247         __aligned_u64 jited_line_info;
3248         __u32 nr_jited_line_info;
3249         __u32 line_info_rec_size;
3250         __u32 jited_line_info_rec_size;
3251         __u32 nr_prog_tags;
3252         __aligned_u64 prog_tags;
3253         __u64 run_time_ns;
3254         __u64 run_cnt;
3255 } __attribute__((aligned(8)));
3256 
3257 struct bpf_map_info {
3258         __u32 type;
3259         __u32 id;
3260         __u32 key_size;
3261         __u32 value_size;
3262         __u32 max_entries;
3263         __u32 map_flags;
3264         char  name[BPF_OBJ_NAME_LEN];
3265         __u32 ifindex;
3266         __u32 :32;
3267         __u64 netns_dev;
3268         __u64 netns_ino;
3269         __u32 btf_id;
3270         __u32 btf_key_type_id;
3271         __u32 btf_value_type_id;
3272 } __attribute__((aligned(8)));
3273 
3274 struct bpf_btf_info {
3275         __aligned_u64 btf;
3276         __u32 btf_size;
3277         __u32 id;
3278 } __attribute__((aligned(8)));
3279 
3280 /* User bpf_sock_addr struct to access socket fields and sockaddr struct passed
3281  * by user and intended to be used by socket (e.g. to bind to, depends on
3282  * attach attach type).
3283  */
3284 struct bpf_sock_addr {
3285         __u32 user_family;      /* Allows 4-byte read, but no write. */
3286         __u32 user_ip4;         /* Allows 1,2,4-byte read and 4-byte write.
3287                                  * Stored in network byte order.
3288                                  */
3289         __u32 user_ip6[4];      /* Allows 1,2,4,8-byte read and 4,8-byte write.
3290                                  * Stored in network byte order.
3291                                  */
3292         __u32 user_port;        /* Allows 4-byte read and write.
3293                                  * Stored in network byte order
3294                                  */
3295         __u32 family;           /* Allows 4-byte read, but no write */
3296         __u32 type;             /* Allows 4-byte read, but no write */
3297         __u32 protocol;         /* Allows 4-byte read, but no write */
3298         __u32 msg_src_ip4;      /* Allows 1,2,4-byte read and 4-byte write.
3299                                  * Stored in network byte order.
3300                                  */
3301         __u32 msg_src_ip6[4];   /* Allows 1,2,4,8-byte read and 4,8-byte write.
3302                                  * Stored in network byte order.
3303                                  */
3304         __bpf_md_ptr(struct bpf_sock *, sk);
3305 };
3306 
3307 /* User bpf_sock_ops struct to access socket values and specify request ops
3308  * and their replies.
3309  * Some of this fields are in network (bigendian) byte order and may need
3310  * to be converted before use (bpf_ntohl() defined in samples/bpf/bpf_endian.h).
3311  * New fields can only be added at the end of this structure
3312  */
3313 struct bpf_sock_ops {
3314         __u32 op;
3315         union {
3316                 __u32 args[4];          /* Optionally passed to bpf program */
3317                 __u32 reply;            /* Returned by bpf program          */
3318                 __u32 replylong[4];     /* Optionally returned by bpf prog  */
3319         };
3320         __u32 family;
3321         __u32 remote_ip4;       /* Stored in network byte order */
3322         __u32 local_ip4;        /* Stored in network byte order */
3323         __u32 remote_ip6[4];    /* Stored in network byte order */
3324         __u32 local_ip6[4];     /* Stored in network byte order */
3325         __u32 remote_port;      /* Stored in network byte order */
3326         __u32 local_port;       /* stored in host byte order */
3327         __u32 is_fullsock;      /* Some TCP fields are only valid if
3328                                  * there is a full socket. If not, the
3329                                  * fields read as zero.
3330                                  */
3331         __u32 snd_cwnd;
3332         __u32 srtt_us;          /* Averaged RTT << 3 in usecs */
3333         __u32 bpf_sock_ops_cb_flags; /* flags defined in uapi/linux/tcp.h */
3334         __u32 state;
3335         __u32 rtt_min;
3336         __u32 snd_ssthresh;
3337         __u32 rcv_nxt;
3338         __u32 snd_nxt;
3339         __u32 snd_una;
3340         __u32 mss_cache;
3341         __u32 ecn_flags;
3342         __u32 rate_delivered;
3343         __u32 rate_interval_us;
3344         __u32 packets_out;
3345         __u32 retrans_out;
3346         __u32 total_retrans;
3347         __u32 segs_in;
3348         __u32 data_segs_in;
3349         __u32 segs_out;
3350         __u32 data_segs_out;
3351         __u32 lost_out;
3352         __u32 sacked_out;
3353         __u32 sk_txhash;
3354         __u64 bytes_received;
3355         __u64 bytes_acked;
3356         __bpf_md_ptr(struct bpf_sock *, sk);
3357 };
3358 
3359 /* Definitions for bpf_sock_ops_cb_flags */
3360 #define BPF_SOCK_OPS_RTO_CB_FLAG        (1<<0)
3361 #define BPF_SOCK_OPS_RETRANS_CB_FLAG    (1<<1)
3362 #define BPF_SOCK_OPS_STATE_CB_FLAG      (1<<2)
3363 #define BPF_SOCK_OPS_RTT_CB_FLAG        (1<<3)
3364 #define BPF_SOCK_OPS_ALL_CB_FLAGS       0xF             /* Mask of all currently
3365                                                          * supported cb flags
3366                                                          */
3367 
3368 /* List of known BPF sock_ops operators.
3369  * New entries can only be added at the end
3370  */
3371 enum {
3372         BPF_SOCK_OPS_VOID,
3373         BPF_SOCK_OPS_TIMEOUT_INIT,      /* Should return SYN-RTO value to use or
3374                                          * -1 if default value should be used
3375                                          */
3376         BPF_SOCK_OPS_RWND_INIT,         /* Should return initial advertized
3377                                          * window (in packets) or -1 if default
3378                                          * value should be used
3379                                          */
3380         BPF_SOCK_OPS_TCP_CONNECT_CB,    /* Calls BPF program right before an
3381                                          * active connection is initialized
3382                                          */
3383         BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB,     /* Calls BPF program when an
3384                                                  * active connection is
3385                                                  * established
3386                                                  */
3387         BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB,    /* Calls BPF program when a
3388                                                  * passive connection is
3389                                                  * established
3390                                                  */
3391         BPF_SOCK_OPS_NEEDS_ECN,         /* If connection's congestion control
3392                                          * needs ECN
3393                                          */
3394         BPF_SOCK_OPS_BASE_RTT,          /* Get base RTT. The correct value is
3395                                          * based on the path and may be
3396                                          * dependent on the congestion control
3397                                          * algorithm. In general it indicates
3398                                          * a congestion threshold. RTTs above
3399                                          * this indicate congestion
3400                                          */
3401         BPF_SOCK_OPS_RTO_CB,            /* Called when an RTO has triggered.
3402                                          * Arg1: value of icsk_retransmits
3403                                          * Arg2: value of icsk_rto
3404                                          * Arg3: whether RTO has expired
3405                                          */
3406         BPF_SOCK_OPS_RETRANS_CB,        /* Called when skb is retransmitted.
3407                                          * Arg1: sequence number of 1st byte
3408                                          * Arg2: # segments
3409                                          * Arg3: return value of
3410                                          *       tcp_transmit_skb (0 => success)
3411                                          */
3412         BPF_SOCK_OPS_STATE_CB,          /* Called when TCP changes state.
3413                                          * Arg1: old_state
3414                                          * Arg2: new_state
3415                                          */
3416         BPF_SOCK_OPS_TCP_LISTEN_CB,     /* Called on listen(2), right after
3417                                          * socket transition to LISTEN state.
3418                                          */
3419         BPF_SOCK_OPS_RTT_CB,            /* Called on every RTT.
3420                                          */
3421 };
3422 
3423 /* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
3424  * changes between the TCP and BPF versions. Ideally this should never happen.
3425  * If it does, we need to add code to convert them before calling
3426  * the BPF sock_ops function.
3427  */
3428 enum {
3429         BPF_TCP_ESTABLISHED = 1,
3430         BPF_TCP_SYN_SENT,
3431         BPF_TCP_SYN_RECV,
3432         BPF_TCP_FIN_WAIT1,
3433         BPF_TCP_FIN_WAIT2,
3434         BPF_TCP_TIME_WAIT,
3435         BPF_TCP_CLOSE,
3436         BPF_TCP_CLOSE_WAIT,
3437         BPF_TCP_LAST_ACK,
3438         BPF_TCP_LISTEN,
3439         BPF_TCP_CLOSING,        /* Now a valid state */
3440         BPF_TCP_NEW_SYN_RECV,
3441 
3442         BPF_TCP_MAX_STATES      /* Leave at the end! */
3443 };
3444 
3445 #define TCP_BPF_IW              1001    /* Set TCP initial congestion window */
3446 #define TCP_BPF_SNDCWND_CLAMP   1002    /* Set sndcwnd_clamp */
3447 
3448 struct bpf_perf_event_value {
3449         __u64 counter;
3450         __u64 enabled;
3451         __u64 running;
3452 };
3453 
3454 #define BPF_DEVCG_ACC_MKNOD     (1ULL << 0)
3455 #define BPF_DEVCG_ACC_READ      (1ULL << 1)
3456 #define BPF_DEVCG_ACC_WRITE     (1ULL << 2)
3457 
3458 #define BPF_DEVCG_DEV_BLOCK     (1ULL << 0)
3459 #define BPF_DEVCG_DEV_CHAR      (1ULL << 1)
3460 
3461 struct bpf_cgroup_dev_ctx {
3462         /* access_type encoded as (BPF_DEVCG_ACC_* << 16) | BPF_DEVCG_DEV_* */
3463         __u32 access_type;
3464         __u32 major;
3465         __u32 minor;
3466 };
3467 
3468 struct bpf_raw_tracepoint_args {
3469         __u64 args[0];
3470 };
3471 
3472 /* DIRECT:  Skip the FIB rules and go to FIB table associated with device
3473  * OUTPUT:  Do lookup from egress perspective; default is ingress
3474  */
3475 #define BPF_FIB_LOOKUP_DIRECT  (1U << 0)
3476 #define BPF_FIB_LOOKUP_OUTPUT  (1U << 1)
3477 
3478 enum {
3479         BPF_FIB_LKUP_RET_SUCCESS,      /* lookup successful */
3480         BPF_FIB_LKUP_RET_BLACKHOLE,    /* dest is blackholed; can be dropped */
3481         BPF_FIB_LKUP_RET_UNREACHABLE,  /* dest is unreachable; can be dropped */
3482         BPF_FIB_LKUP_RET_PROHIBIT,     /* dest not allowed; can be dropped */
3483         BPF_FIB_LKUP_RET_NOT_FWDED,    /* packet is not forwarded */
3484         BPF_FIB_LKUP_RET_FWD_DISABLED, /* fwding is not enabled on ingress */
3485         BPF_FIB_LKUP_RET_UNSUPP_LWT,   /* fwd requires encapsulation */
3486         BPF_FIB_LKUP_RET_NO_NEIGH,     /* no neighbor entry for nh */
3487         BPF_FIB_LKUP_RET_FRAG_NEEDED,  /* fragmentation required to fwd */
3488 };
3489 
3490 struct bpf_fib_lookup {
3491         /* input:  network family for lookup (AF_INET, AF_INET6)
3492          * output: network family of egress nexthop
3493          */
3494         __u8    family;
3495 
3496         /* set if lookup is to consider L4 data - e.g., FIB rules */
3497         __u8    l4_protocol;
3498         __be16  sport;
3499         __be16  dport;
3500 
3501         /* total length of packet from network header - used for MTU check */
3502         __u16   tot_len;
3503 
3504         /* input: L3 device index for lookup
3505          * output: device index from FIB lookup
3506          */
3507         __u32   ifindex;
3508 
3509         union {
3510                 /* inputs to lookup */
3511                 __u8    tos;            /* AF_INET  */
3512                 __be32  flowinfo;       /* AF_INET6, flow_label + priority */
3513 
3514                 /* output: metric of fib result (IPv4/IPv6 only) */
3515                 __u32   rt_metric;
3516         };
3517 
3518         union {
3519                 __be32          ipv4_src;
3520                 __u32           ipv6_src[4];  /* in6_addr; network order */
3521         };
3522 
3523         /* input to bpf_fib_lookup, ipv{4,6}_dst is destination address in
3524          * network header. output: bpf_fib_lookup sets to gateway address
3525          * if FIB lookup returns gateway route
3526          */
3527         union {
3528                 __be32          ipv4_dst;
3529                 __u32           ipv6_dst[4];  /* in6_addr; network order */
3530         };
3531 
3532         /* output */
3533         __be16  h_vlan_proto;
3534         __be16  h_vlan_TCI;
3535         __u8    smac[6];     /* ETH_ALEN */
3536         __u8    dmac[6];     /* ETH_ALEN */
3537 };
3538 
3539 enum bpf_task_fd_type {
3540         BPF_FD_TYPE_RAW_TRACEPOINT,     /* tp name */
3541         BPF_FD_TYPE_TRACEPOINT,         /* tp name */
3542         BPF_FD_TYPE_KPROBE,             /* (symbol + offset) or addr */
3543         BPF_FD_TYPE_KRETPROBE,          /* (symbol + offset) or addr */
3544         BPF_FD_TYPE_UPROBE,             /* filename + offset */
3545         BPF_FD_TYPE_URETPROBE,          /* filename + offset */
3546 };
3547 
3548 #define BPF_FLOW_DISSECTOR_F_PARSE_1ST_FRAG             (1U << 0)
3549 #define BPF_FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL         (1U << 1)
3550 #define BPF_FLOW_DISSECTOR_F_STOP_AT_ENCAP              (1U << 2)
3551 
3552 struct bpf_flow_keys {
3553         __u16   nhoff;
3554         __u16   thoff;
3555         __u16   addr_proto;                     /* ETH_P_* of valid addrs */
3556         __u8    is_frag;
3557         __u8    is_first_frag;
3558         __u8    is_encap;
3559         __u8    ip_proto;
3560         __be16  n_proto;
3561         __be16  sport;
3562         __be16  dport;
3563         union {
3564                 struct {
3565                         __be32  ipv4_src;
3566                         __be32  ipv4_dst;
3567                 };
3568                 struct {
3569                         __u32   ipv6_src[4];    /* in6_addr; network order */
3570                         __u32   ipv6_dst[4];    /* in6_addr; network order */
3571                 };
3572         };
3573         __u32   flags;
3574         __be32  flow_label;
3575 };
3576 
3577 struct bpf_func_info {
3578         __u32   insn_off;
3579         __u32   type_id;
3580 };
3581 
3582 #define BPF_LINE_INFO_LINE_NUM(line_col)        ((line_col) >> 10)
3583 #define BPF_LINE_INFO_LINE_COL(line_col)        ((line_col) & 0x3ff)
3584 
3585 struct bpf_line_info {
3586         __u32   insn_off;
3587         __u32   file_name_off;
3588         __u32   line_off;
3589         __u32   line_col;
3590 };
3591 
3592 struct bpf_spin_lock {
3593         __u32   val;
3594 };
3595 
3596 struct bpf_sysctl {
3597         __u32   write;          /* Sysctl is being read (= 0) or written (= 1).
3598                                  * Allows 1,2,4-byte read, but no write.
3599                                  */
3600         __u32   file_pos;       /* Sysctl file position to read from, write to.
3601                                  * Allows 1,2,4-byte read an 4-byte write.
3602                                  */
3603 };
3604 
3605 struct bpf_sockopt {
3606         __bpf_md_ptr(struct bpf_sock *, sk);
3607         __bpf_md_ptr(void *, optval);
3608         __bpf_md_ptr(void *, optval_end);
3609 
3610         __s32   level;
3611         __s32   optname;
3612         __s32   optlen;
3613         __s32   retval;
3614 };
3615 
3616 #endif /* _UAPI__LINUX_BPF_H__ */

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