1/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
2 *
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of version 2 of the GNU General Public
5 * License as published by the Free Software Foundation.
6 */
7#ifndef _LINUX_BPF_H
8#define _LINUX_BPF_H 1
9
10#include <uapi/linux/bpf.h>
11#include <linux/workqueue.h>
12#include <linux/file.h>
13
14struct bpf_map;
15
16/* map is generic key/value storage optionally accesible by eBPF programs */
17struct bpf_map_ops {
18	/* funcs callable from userspace (via syscall) */
19	struct bpf_map *(*map_alloc)(union bpf_attr *attr);
20	void (*map_free)(struct bpf_map *);
21	int (*map_get_next_key)(struct bpf_map *map, void *key, void *next_key);
22
23	/* funcs callable from userspace and from eBPF programs */
24	void *(*map_lookup_elem)(struct bpf_map *map, void *key);
25	int (*map_update_elem)(struct bpf_map *map, void *key, void *value, u64 flags);
26	int (*map_delete_elem)(struct bpf_map *map, void *key);
27};
28
29struct bpf_map {
30	atomic_t refcnt;
31	enum bpf_map_type map_type;
32	u32 key_size;
33	u32 value_size;
34	u32 max_entries;
35	const struct bpf_map_ops *ops;
36	struct work_struct work;
37};
38
39struct bpf_map_type_list {
40	struct list_head list_node;
41	const struct bpf_map_ops *ops;
42	enum bpf_map_type type;
43};
44
45/* function argument constraints */
46enum bpf_arg_type {
47	ARG_DONTCARE = 0,	/* unused argument in helper function */
48
49	/* the following constraints used to prototype
50	 * bpf_map_lookup/update/delete_elem() functions
51	 */
52	ARG_CONST_MAP_PTR,	/* const argument used as pointer to bpf_map */
53	ARG_PTR_TO_MAP_KEY,	/* pointer to stack used as map key */
54	ARG_PTR_TO_MAP_VALUE,	/* pointer to stack used as map value */
55
56	/* the following constraints used to prototype bpf_memcmp() and other
57	 * functions that access data on eBPF program stack
58	 */
59	ARG_PTR_TO_STACK,	/* any pointer to eBPF program stack */
60	ARG_CONST_STACK_SIZE,	/* number of bytes accessed from stack */
61
62	ARG_PTR_TO_CTX,		/* pointer to context */
63	ARG_ANYTHING,		/* any (initialized) argument is ok */
64};
65
66/* type of values returned from helper functions */
67enum bpf_return_type {
68	RET_INTEGER,			/* function returns integer */
69	RET_VOID,			/* function doesn't return anything */
70	RET_PTR_TO_MAP_VALUE_OR_NULL,	/* returns a pointer to map elem value or NULL */
71};
72
73/* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs
74 * to in-kernel helper functions and for adjusting imm32 field in BPF_CALL
75 * instructions after verifying
76 */
77struct bpf_func_proto {
78	u64 (*func)(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
79	bool gpl_only;
80	enum bpf_return_type ret_type;
81	enum bpf_arg_type arg1_type;
82	enum bpf_arg_type arg2_type;
83	enum bpf_arg_type arg3_type;
84	enum bpf_arg_type arg4_type;
85	enum bpf_arg_type arg5_type;
86};
87
88/* bpf_context is intentionally undefined structure. Pointer to bpf_context is
89 * the first argument to eBPF programs.
90 * For socket filters: 'struct bpf_context *' == 'struct sk_buff *'
91 */
92struct bpf_context;
93
94enum bpf_access_type {
95	BPF_READ = 1,
96	BPF_WRITE = 2
97};
98
99struct bpf_verifier_ops {
100	/* return eBPF function prototype for verification */
101	const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id);
102
103	/* return true if 'size' wide access at offset 'off' within bpf_context
104	 * with 'type' (read or write) is allowed
105	 */
106	bool (*is_valid_access)(int off, int size, enum bpf_access_type type);
107
108	u32 (*convert_ctx_access)(int dst_reg, int src_reg, int ctx_off,
109				  struct bpf_insn *insn);
110};
111
112struct bpf_prog_type_list {
113	struct list_head list_node;
114	const struct bpf_verifier_ops *ops;
115	enum bpf_prog_type type;
116};
117
118struct bpf_prog;
119
120struct bpf_prog_aux {
121	atomic_t refcnt;
122	u32 used_map_cnt;
123	const struct bpf_verifier_ops *ops;
124	struct bpf_map **used_maps;
125	struct bpf_prog *prog;
126	struct work_struct work;
127};
128
129#ifdef CONFIG_BPF_SYSCALL
130void bpf_register_prog_type(struct bpf_prog_type_list *tl);
131void bpf_register_map_type(struct bpf_map_type_list *tl);
132
133struct bpf_prog *bpf_prog_get(u32 ufd);
134void bpf_prog_put(struct bpf_prog *prog);
135
136struct bpf_map *bpf_map_get(struct fd f);
137void bpf_map_put(struct bpf_map *map);
138
139/* verify correctness of eBPF program */
140int bpf_check(struct bpf_prog **fp, union bpf_attr *attr);
141#else
142static inline void bpf_register_prog_type(struct bpf_prog_type_list *tl)
143{
144}
145
146static inline struct bpf_prog *bpf_prog_get(u32 ufd)
147{
148	return ERR_PTR(-EOPNOTSUPP);
149}
150
151static inline void bpf_prog_put(struct bpf_prog *prog)
152{
153}
154#endif /* CONFIG_BPF_SYSCALL */
155
156/* verifier prototypes for helper functions called from eBPF programs */
157extern const struct bpf_func_proto bpf_map_lookup_elem_proto;
158extern const struct bpf_func_proto bpf_map_update_elem_proto;
159extern const struct bpf_func_proto bpf_map_delete_elem_proto;
160
161extern const struct bpf_func_proto bpf_get_prandom_u32_proto;
162extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;
163
164#endif /* _LINUX_BPF_H */
165