root/net/ipv6/calipso.c

DEFINITIONS

1. calipso_cache_entry_free
2. calipso_map_cache_hash
3. calipso_cache_init
4. calipso_cache_invalidate
5. calipso_cache_check
6. calipso_cache_add
7. calipso_doi_search
8. calipso_doi_add
9. calipso_doi_free
10. calipso_doi_free_rcu
11. calipso_doi_remove
12. calipso_doi_getdef
13. calipso_doi_putdef
14. calipso_doi_walk
15. calipso_validate
16. calipso_map_cat_hton
17. calipso_map_cat_ntoh
18. calipso_pad_write
19. calipso_genopt
20. calipso_opt_update
21. calipso_tlv_len
22. calipso_opt_find
23. calipso_opt_insert
24. calipso_opt_del
25. calipso_opt_getattr
26. calipso_sock_getattr
27. calipso_sock_setattr
28. calipso_sock_delattr
29. calipso_req_setattr
30. calipso_req_delattr
31. calipso_skbuff_optptr
32. calipso_skbuff_setattr
33. calipso_skbuff_delattr
34. calipso_init
35. calipso_exit

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * CALIPSO - Common Architecture Label IPv6 Security Option
   4  *
   5  * This is an implementation of the CALIPSO protocol as specified in
   6  * RFC 5570.
   7  *
   8  * Authors: Paul Moore <paul.moore@hp.com>
   9  *          Huw Davies <huw@codeweavers.com>
  10  */
  11 
  12 /* (c) Copyright Hewlett-Packard Development Company, L.P., 2006, 2008
  13  * (c) Copyright Huw Davies <huw@codeweavers.com>, 2015
  14  */
  15 
  16 #include <linux/init.h>
  17 #include <linux/types.h>
  18 #include <linux/rcupdate.h>
  19 #include <linux/list.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/string.h>
  22 #include <linux/jhash.h>
  23 #include <linux/audit.h>
  24 #include <linux/slab.h>
  25 #include <net/ip.h>
  26 #include <net/icmp.h>
  27 #include <net/tcp.h>
  28 #include <net/netlabel.h>
  29 #include <net/calipso.h>
  30 #include <linux/atomic.h>
  31 #include <linux/bug.h>
  32 #include <asm/unaligned.h>
  33 #include <linux/crc-ccitt.h>
  34 
  35 /* Maximium size of the calipso option including
  36  * the two-byte TLV header.
  37  */
  38 #define CALIPSO_OPT_LEN_MAX (2 + 252)
  39 
  40 /* Size of the minimum calipso option including
  41  * the two-byte TLV header.
  42  */
  43 #define CALIPSO_HDR_LEN (2 + 8)
  44 
  45 /* Maximium size of the calipso option including
  46  * the two-byte TLV header and upto 3 bytes of
  47  * leading pad and 7 bytes of trailing pad.
  48  */
  49 #define CALIPSO_OPT_LEN_MAX_WITH_PAD (3 + CALIPSO_OPT_LEN_MAX + 7)
  50 
  51  /* Maximium size of u32 aligned buffer required to hold calipso
  52   * option.  Max of 3 initial pad bytes starting from buffer + 3.
  53   * i.e. the worst case is when the previous tlv finishes on 4n + 3.
  54   */
  55 #define CALIPSO_MAX_BUFFER (6 + CALIPSO_OPT_LEN_MAX)
  56 
  57 /* List of available DOI definitions */
  58 static DEFINE_SPINLOCK(calipso_doi_list_lock);
  59 static LIST_HEAD(calipso_doi_list);
  60 
  61 /* Label mapping cache */
  62 int calipso_cache_enabled = 1;
  63 int calipso_cache_bucketsize = 10;
  64 #define CALIPSO_CACHE_BUCKETBITS     7
  65 #define CALIPSO_CACHE_BUCKETS        BIT(CALIPSO_CACHE_BUCKETBITS)
  66 #define CALIPSO_CACHE_REORDERLIMIT   10
  67 struct calipso_map_cache_bkt {
  68         spinlock_t lock;
  69         u32 size;
  70         struct list_head list;
  71 };
  72 
  73 struct calipso_map_cache_entry {
  74         u32 hash;
  75         unsigned char *key;
  76         size_t key_len;
  77 
  78         struct netlbl_lsm_cache *lsm_data;
  79 
  80         u32 activity;
  81         struct list_head list;
  82 };
  83 
  84 static struct calipso_map_cache_bkt *calipso_cache;
  85 
  86 /* Label Mapping Cache Functions
  87  */
  88 
  89 /**
  90  * calipso_cache_entry_free - Frees a cache entry
  91  * @entry: the entry to free
  92  *
  93  * Description:
  94  * This function frees the memory associated with a cache entry including the
  95  * LSM cache data if there are no longer any users, i.e. reference count == 0.
  96  *
  97  */
  98 static void calipso_cache_entry_free(struct calipso_map_cache_entry *entry)
  99 {
 100         if (entry->lsm_data)
 101                 netlbl_secattr_cache_free(entry->lsm_data);
 102         kfree(entry->key);
 103         kfree(entry);
 104 }
 105 
 106 /**
 107  * calipso_map_cache_hash - Hashing function for the CALIPSO cache
 108  * @key: the hash key
 109  * @key_len: the length of the key in bytes
 110  *
 111  * Description:
 112  * The CALIPSO tag hashing function.  Returns a 32-bit hash value.
 113  *
 114  */
 115 static u32 calipso_map_cache_hash(const unsigned char *key, u32 key_len)
 116 {
 117         return jhash(key, key_len, 0);
 118 }
 119 
 120 /**
 121  * calipso_cache_init - Initialize the CALIPSO cache
 122  *
 123  * Description:
 124  * Initializes the CALIPSO label mapping cache, this function should be called
 125  * before any of the other functions defined in this file.  Returns zero on
 126  * success, negative values on error.
 127  *
 128  */
 129 static int __init calipso_cache_init(void)
 130 {
 131         u32 iter;
 132 
 133         calipso_cache = kcalloc(CALIPSO_CACHE_BUCKETS,
 134                                 sizeof(struct calipso_map_cache_bkt),
 135                                 GFP_KERNEL);
 136         if (!calipso_cache)
 137                 return -ENOMEM;
 138 
 139         for (iter = 0; iter < CALIPSO_CACHE_BUCKETS; iter++) {
 140                 spin_lock_init(&calipso_cache[iter].lock);
 141                 calipso_cache[iter].size = 0;
 142                 INIT_LIST_HEAD(&calipso_cache[iter].list);
 143         }
 144 
 145         return 0;
 146 }
 147 
 148 /**
 149  * calipso_cache_invalidate - Invalidates the current CALIPSO cache
 150  *
 151  * Description:
 152  * Invalidates and frees any entries in the CALIPSO cache.  Returns zero on
 153  * success and negative values on failure.
 154  *
 155  */
 156 static void calipso_cache_invalidate(void)
 157 {
 158         struct calipso_map_cache_entry *entry, *tmp_entry;
 159         u32 iter;
 160 
 161         for (iter = 0; iter < CALIPSO_CACHE_BUCKETS; iter++) {
 162                 spin_lock_bh(&calipso_cache[iter].lock);
 163                 list_for_each_entry_safe(entry,
 164                                          tmp_entry,
 165                                          &calipso_cache[iter].list, list) {
 166                         list_del(&entry->list);
 167                         calipso_cache_entry_free(entry);
 168                 }
 169                 calipso_cache[iter].size = 0;
 170                 spin_unlock_bh(&calipso_cache[iter].lock);
 171         }
 172 }
 173 
 174 /**
 175  * calipso_cache_check - Check the CALIPSO cache for a label mapping
 176  * @key: the buffer to check
 177  * @key_len: buffer length in bytes
 178  * @secattr: the security attribute struct to use
 179  *
 180  * Description:
 181  * This function checks the cache to see if a label mapping already exists for
 182  * the given key.  If there is a match then the cache is adjusted and the
 183  * @secattr struct is populated with the correct LSM security attributes.  The
 184  * cache is adjusted in the following manner if the entry is not already the
 185  * first in the cache bucket:
 186  *
 187  *  1. The cache entry's activity counter is incremented
 188  *  2. The previous (higher ranking) entry's activity counter is decremented
 189  *  3. If the difference between the two activity counters is geater than
 190  *     CALIPSO_CACHE_REORDERLIMIT the two entries are swapped
 191  *
 192  * Returns zero on success, -ENOENT for a cache miss, and other negative values
 193  * on error.
 194  *
 195  */
 196 static int calipso_cache_check(const unsigned char *key,
 197                                u32 key_len,
 198                                struct netlbl_lsm_secattr *secattr)
 199 {
 200         u32 bkt;
 201         struct calipso_map_cache_entry *entry;
 202         struct calipso_map_cache_entry *prev_entry = NULL;
 203         u32 hash;
 204 
 205         if (!calipso_cache_enabled)
 206                 return -ENOENT;
 207 
 208         hash = calipso_map_cache_hash(key, key_len);
 209         bkt = hash & (CALIPSO_CACHE_BUCKETS - 1);
 210         spin_lock_bh(&calipso_cache[bkt].lock);
 211         list_for_each_entry(entry, &calipso_cache[bkt].list, list) {
 212                 if (entry->hash == hash &&
 213                     entry->key_len == key_len &&
 214                     memcmp(entry->key, key, key_len) == 0) {
 215                         entry->activity += 1;
 216                         refcount_inc(&entry->lsm_data->refcount);
 217                         secattr->cache = entry->lsm_data;
 218                         secattr->flags |= NETLBL_SECATTR_CACHE;
 219                         secattr->type = NETLBL_NLTYPE_CALIPSO;
 220                         if (!prev_entry) {
 221                                 spin_unlock_bh(&calipso_cache[bkt].lock);
 222                                 return 0;
 223                         }
 224 
 225                         if (prev_entry->activity > 0)
 226                                 prev_entry->activity -= 1;
 227                         if (entry->activity > prev_entry->activity &&
 228                             entry->activity - prev_entry->activity >
 229                             CALIPSO_CACHE_REORDERLIMIT) {
 230                                 __list_del(entry->list.prev, entry->list.next);
 231                                 __list_add(&entry->list,
 232                                            prev_entry->list.prev,
 233                                            &prev_entry->list);
 234                         }
 235 
 236                         spin_unlock_bh(&calipso_cache[bkt].lock);
 237                         return 0;
 238                 }
 239                 prev_entry = entry;
 240         }
 241         spin_unlock_bh(&calipso_cache[bkt].lock);
 242 
 243         return -ENOENT;
 244 }
 245 
 246 /**
 247  * calipso_cache_add - Add an entry to the CALIPSO cache
 248  * @calipso_ptr: the CALIPSO option
 249  * @secattr: the packet's security attributes
 250  *
 251  * Description:
 252  * Add a new entry into the CALIPSO label mapping cache.  Add the new entry to
 253  * head of the cache bucket's list, if the cache bucket is out of room remove
 254  * the last entry in the list first.  It is important to note that there is
 255  * currently no checking for duplicate keys.  Returns zero on success,
 256  * negative values on failure.  The key stored starts at calipso_ptr + 2,
 257  * i.e. the type and length bytes are not stored, this corresponds to
 258  * calipso_ptr[1] bytes of data.
 259  *
 260  */
 261 static int calipso_cache_add(const unsigned char *calipso_ptr,
 262                              const struct netlbl_lsm_secattr *secattr)
 263 {
 264         int ret_val = -EPERM;
 265         u32 bkt;
 266         struct calipso_map_cache_entry *entry = NULL;
 267         struct calipso_map_cache_entry *old_entry = NULL;
 268         u32 calipso_ptr_len;
 269 
 270         if (!calipso_cache_enabled || calipso_cache_bucketsize <= 0)
 271                 return 0;
 272 
 273         calipso_ptr_len = calipso_ptr[1];
 274 
 275         entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
 276         if (!entry)
 277                 return -ENOMEM;
 278         entry->key = kmemdup(calipso_ptr + 2, calipso_ptr_len, GFP_ATOMIC);
 279         if (!entry->key) {
 280                 ret_val = -ENOMEM;
 281                 goto cache_add_failure;
 282         }
 283         entry->key_len = calipso_ptr_len;
 284         entry->hash = calipso_map_cache_hash(calipso_ptr, calipso_ptr_len);
 285         refcount_inc(&secattr->cache->refcount);
 286         entry->lsm_data = secattr->cache;
 287 
 288         bkt = entry->hash & (CALIPSO_CACHE_BUCKETS - 1);
 289         spin_lock_bh(&calipso_cache[bkt].lock);
 290         if (calipso_cache[bkt].size < calipso_cache_bucketsize) {
 291                 list_add(&entry->list, &calipso_cache[bkt].list);
 292                 calipso_cache[bkt].size += 1;
 293         } else {
 294                 old_entry = list_entry(calipso_cache[bkt].list.prev,
 295                                        struct calipso_map_cache_entry, list);
 296                 list_del(&old_entry->list);
 297                 list_add(&entry->list, &calipso_cache[bkt].list);
 298                 calipso_cache_entry_free(old_entry);
 299         }
 300         spin_unlock_bh(&calipso_cache[bkt].lock);
 301 
 302         return 0;
 303 
 304 cache_add_failure:
 305         if (entry)
 306                 calipso_cache_entry_free(entry);
 307         return ret_val;
 308 }
 309 
 310 /* DOI List Functions
 311  */
 312 
 313 /**
 314  * calipso_doi_search - Searches for a DOI definition
 315  * @doi: the DOI to search for
 316  *
 317  * Description:
 318  * Search the DOI definition list for a DOI definition with a DOI value that
 319  * matches @doi.  The caller is responsible for calling rcu_read_[un]lock().
 320  * Returns a pointer to the DOI definition on success and NULL on failure.
 321  */
 322 static struct calipso_doi *calipso_doi_search(u32 doi)
 323 {
 324         struct calipso_doi *iter;
 325 
 326         list_for_each_entry_rcu(iter, &calipso_doi_list, list)
 327                 if (iter->doi == doi && refcount_read(&iter->refcount))
 328                         return iter;
 329         return NULL;
 330 }
 331 
 332 /**
 333  * calipso_doi_add - Add a new DOI to the CALIPSO protocol engine
 334  * @doi_def: the DOI structure
 335  * @audit_info: NetLabel audit information
 336  *
 337  * Description:
 338  * The caller defines a new DOI for use by the CALIPSO engine and calls this
 339  * function to add it to the list of acceptable domains.  The caller must
 340  * ensure that the mapping table specified in @doi_def->map meets all of the
 341  * requirements of the mapping type (see calipso.h for details).  Returns
 342  * zero on success and non-zero on failure.
 343  *
 344  */
 345 static int calipso_doi_add(struct calipso_doi *doi_def,
 346                            struct netlbl_audit *audit_info)
 347 {
 348         int ret_val = -EINVAL;
 349         u32 doi;
 350         u32 doi_type;
 351         struct audit_buffer *audit_buf;
 352 
 353         doi = doi_def->doi;
 354         doi_type = doi_def->type;
 355 
 356         if (doi_def->doi == CALIPSO_DOI_UNKNOWN)
 357                 goto doi_add_return;
 358 
 359         refcount_set(&doi_def->refcount, 1);
 360 
 361         spin_lock(&calipso_doi_list_lock);
 362         if (calipso_doi_search(doi_def->doi)) {
 363                 spin_unlock(&calipso_doi_list_lock);
 364                 ret_val = -EEXIST;
 365                 goto doi_add_return;
 366         }
 367         list_add_tail_rcu(&doi_def->list, &calipso_doi_list);
 368         spin_unlock(&calipso_doi_list_lock);
 369         ret_val = 0;
 370 
 371 doi_add_return:
 372         audit_buf = netlbl_audit_start(AUDIT_MAC_CALIPSO_ADD, audit_info);
 373         if (audit_buf) {
 374                 const char *type_str;
 375 
 376                 switch (doi_type) {
 377                 case CALIPSO_MAP_PASS:
 378                         type_str = "pass";
 379                         break;
 380                 default:
 381                         type_str = "(unknown)";
 382                 }
 383                 audit_log_format(audit_buf,
 384                                  " calipso_doi=%u calipso_type=%s res=%u",
 385                                  doi, type_str, ret_val == 0 ? 1 : 0);
 386                 audit_log_end(audit_buf);
 387         }
 388 
 389         return ret_val;
 390 }
 391 
 392 /**
 393  * calipso_doi_free - Frees a DOI definition
 394  * @doi_def: the DOI definition
 395  *
 396  * Description:
 397  * This function frees all of the memory associated with a DOI definition.
 398  *
 399  */
 400 static void calipso_doi_free(struct calipso_doi *doi_def)
 401 {
 402         kfree(doi_def);
 403 }
 404 
 405 /**
 406  * calipso_doi_free_rcu - Frees a DOI definition via the RCU pointer
 407  * @entry: the entry's RCU field
 408  *
 409  * Description:
 410  * This function is designed to be used as a callback to the call_rcu()
 411  * function so that the memory allocated to the DOI definition can be released
 412  * safely.
 413  *
 414  */
 415 static void calipso_doi_free_rcu(struct rcu_head *entry)
 416 {
 417         struct calipso_doi *doi_def;
 418 
 419         doi_def = container_of(entry, struct calipso_doi, rcu);
 420         calipso_doi_free(doi_def);
 421 }
 422 
 423 /**
 424  * calipso_doi_remove - Remove an existing DOI from the CALIPSO protocol engine
 425  * @doi: the DOI value
 426  * @audit_secid: the LSM secid to use in the audit message
 427  *
 428  * Description:
 429  * Removes a DOI definition from the CALIPSO engine.  The NetLabel routines will
 430  * be called to release their own LSM domain mappings as well as our own
 431  * domain list.  Returns zero on success and negative values on failure.
 432  *
 433  */
 434 static int calipso_doi_remove(u32 doi, struct netlbl_audit *audit_info)
 435 {
 436         int ret_val;
 437         struct calipso_doi *doi_def;
 438         struct audit_buffer *audit_buf;
 439 
 440         spin_lock(&calipso_doi_list_lock);
 441         doi_def = calipso_doi_search(doi);
 442         if (!doi_def) {
 443                 spin_unlock(&calipso_doi_list_lock);
 444                 ret_val = -ENOENT;
 445                 goto doi_remove_return;
 446         }
 447         if (!refcount_dec_and_test(&doi_def->refcount)) {
 448                 spin_unlock(&calipso_doi_list_lock);
 449                 ret_val = -EBUSY;
 450                 goto doi_remove_return;
 451         }
 452         list_del_rcu(&doi_def->list);
 453         spin_unlock(&calipso_doi_list_lock);
 454 
 455         call_rcu(&doi_def->rcu, calipso_doi_free_rcu);
 456         ret_val = 0;
 457 
 458 doi_remove_return:
 459         audit_buf = netlbl_audit_start(AUDIT_MAC_CALIPSO_DEL, audit_info);
 460         if (audit_buf) {
 461                 audit_log_format(audit_buf,
 462                                  " calipso_doi=%u res=%u",
 463                                  doi, ret_val == 0 ? 1 : 0);
 464                 audit_log_end(audit_buf);
 465         }
 466 
 467         return ret_val;
 468 }
 469 
 470 /**
 471  * calipso_doi_getdef - Returns a reference to a valid DOI definition
 472  * @doi: the DOI value
 473  *
 474  * Description:
 475  * Searches for a valid DOI definition and if one is found it is returned to
 476  * the caller.  Otherwise NULL is returned.  The caller must ensure that
 477  * calipso_doi_putdef() is called when the caller is done.
 478  *
 479  */
 480 static struct calipso_doi *calipso_doi_getdef(u32 doi)
 481 {
 482         struct calipso_doi *doi_def;
 483 
 484         rcu_read_lock();
 485         doi_def = calipso_doi_search(doi);
 486         if (!doi_def)
 487                 goto doi_getdef_return;
 488         if (!refcount_inc_not_zero(&doi_def->refcount))
 489                 doi_def = NULL;
 490 
 491 doi_getdef_return:
 492         rcu_read_unlock();
 493         return doi_def;
 494 }
 495 
 496 /**
 497  * calipso_doi_putdef - Releases a reference for the given DOI definition
 498  * @doi_def: the DOI definition
 499  *
 500  * Description:
 501  * Releases a DOI definition reference obtained from calipso_doi_getdef().
 502  *
 503  */
 504 static void calipso_doi_putdef(struct calipso_doi *doi_def)
 505 {
 506         if (!doi_def)
 507                 return;
 508 
 509         if (!refcount_dec_and_test(&doi_def->refcount))
 510                 return;
 511         spin_lock(&calipso_doi_list_lock);
 512         list_del_rcu(&doi_def->list);
 513         spin_unlock(&calipso_doi_list_lock);
 514 
 515         call_rcu(&doi_def->rcu, calipso_doi_free_rcu);
 516 }
 517 
 518 /**
 519  * calipso_doi_walk - Iterate through the DOI definitions
 520  * @skip_cnt: skip past this number of DOI definitions, updated
 521  * @callback: callback for each DOI definition
 522  * @cb_arg: argument for the callback function
 523  *
 524  * Description:
 525  * Iterate over the DOI definition list, skipping the first @skip_cnt entries.
 526  * For each entry call @callback, if @callback returns a negative value stop
 527  * 'walking' through the list and return.  Updates the value in @skip_cnt upon
 528  * return.  Returns zero on success, negative values on failure.
 529  *
 530  */
 531 static int calipso_doi_walk(u32 *skip_cnt,
 532                             int (*callback)(struct calipso_doi *doi_def,
 533                                             void *arg),
 534                             void *cb_arg)
 535 {
 536         int ret_val = -ENOENT;
 537         u32 doi_cnt = 0;
 538         struct calipso_doi *iter_doi;
 539 
 540         rcu_read_lock();
 541         list_for_each_entry_rcu(iter_doi, &calipso_doi_list, list)
 542                 if (refcount_read(&iter_doi->refcount) > 0) {
 543                         if (doi_cnt++ < *skip_cnt)
 544                                 continue;
 545                         ret_val = callback(iter_doi, cb_arg);
 546                         if (ret_val < 0) {
 547                                 doi_cnt--;
 548                                 goto doi_walk_return;
 549                         }
 550                 }
 551 
 552 doi_walk_return:
 553         rcu_read_unlock();
 554         *skip_cnt = doi_cnt;
 555         return ret_val;
 556 }
 557 
 558 /**
 559  * calipso_validate - Validate a CALIPSO option
 560  * @skb: the packet
 561  * @option: the start of the option
 562  *
 563  * Description:
 564  * This routine is called to validate a CALIPSO option.
 565  * If the option is valid then %true is returned, otherwise
 566  * %false is returned.
 567  *
 568  * The caller should have already checked that the length of the
 569  * option (including the TLV header) is >= 10 and that the catmap
 570  * length is consistent with the option length.
 571  *
 572  * We leave checks on the level and categories to the socket layer.
 573  */
 574 bool calipso_validate(const struct sk_buff *skb, const unsigned char *option)
 575 {
 576         struct calipso_doi *doi_def;
 577         bool ret_val;
 578         u16 crc, len = option[1] + 2;
 579         static const u8 zero[2];
 580 
 581         /* The original CRC runs over the option including the TLV header
 582          * with the CRC-16 field (at offset 8) zeroed out. */
 583         crc = crc_ccitt(0xffff, option, 8);
 584         crc = crc_ccitt(crc, zero, sizeof(zero));
 585         if (len > 10)
 586                 crc = crc_ccitt(crc, option + 10, len - 10);
 587         crc = ~crc;
 588         if (option[8] != (crc & 0xff) || option[9] != ((crc >> 8) & 0xff))
 589                 return false;
 590 
 591         rcu_read_lock();
 592         doi_def = calipso_doi_search(get_unaligned_be32(option + 2));
 593         ret_val = !!doi_def;
 594         rcu_read_unlock();
 595 
 596         return ret_val;
 597 }
 598 
 599 /**
 600  * calipso_map_cat_hton - Perform a category mapping from host to network
 601  * @doi_def: the DOI definition
 602  * @secattr: the security attributes
 603  * @net_cat: the zero'd out category bitmap in network/CALIPSO format
 604  * @net_cat_len: the length of the CALIPSO bitmap in bytes
 605  *
 606  * Description:
 607  * Perform a label mapping to translate a local MLS category bitmap to the
 608  * correct CALIPSO bitmap using the given DOI definition.  Returns the minimum
 609  * size in bytes of the network bitmap on success, negative values otherwise.
 610  *
 611  */
 612 static int calipso_map_cat_hton(const struct calipso_doi *doi_def,
 613                                 const struct netlbl_lsm_secattr *secattr,
 614                                 unsigned char *net_cat,
 615                                 u32 net_cat_len)
 616 {
 617         int spot = -1;
 618         u32 net_spot_max = 0;
 619         u32 net_clen_bits = net_cat_len * 8;
 620 
 621         for (;;) {
 622                 spot = netlbl_catmap_walk(secattr->attr.mls.cat,
 623                                           spot + 1);
 624                 if (spot < 0)
 625                         break;
 626                 if (spot >= net_clen_bits)
 627                         return -ENOSPC;
 628                 netlbl_bitmap_setbit(net_cat, spot, 1);
 629 
 630                 if (spot > net_spot_max)
 631                         net_spot_max = spot;
 632         }
 633 
 634         return (net_spot_max / 32 + 1) * 4;
 635 }
 636 
 637 /**
 638  * calipso_map_cat_ntoh - Perform a category mapping from network to host
 639  * @doi_def: the DOI definition
 640  * @net_cat: the category bitmap in network/CALIPSO format
 641  * @net_cat_len: the length of the CALIPSO bitmap in bytes
 642  * @secattr: the security attributes
 643  *
 644  * Description:
 645  * Perform a label mapping to translate a CALIPSO bitmap to the correct local
 646  * MLS category bitmap using the given DOI definition.  Returns zero on
 647  * success, negative values on failure.
 648  *
 649  */
 650 static int calipso_map_cat_ntoh(const struct calipso_doi *doi_def,
 651                                 const unsigned char *net_cat,
 652                                 u32 net_cat_len,
 653                                 struct netlbl_lsm_secattr *secattr)
 654 {
 655         int ret_val;
 656         int spot = -1;
 657         u32 net_clen_bits = net_cat_len * 8;
 658 
 659         for (;;) {
 660                 spot = netlbl_bitmap_walk(net_cat,
 661                                           net_clen_bits,
 662                                           spot + 1,
 663                                           1);
 664                 if (spot < 0) {
 665                         if (spot == -2)
 666                                 return -EFAULT;
 667                         return 0;
 668                 }
 669 
 670                 ret_val = netlbl_catmap_setbit(&secattr->attr.mls.cat,
 671                                                spot,
 672                                                GFP_ATOMIC);
 673                 if (ret_val != 0)
 674                         return ret_val;
 675         }
 676 
 677         return -EINVAL;
 678 }
 679 
 680 /**
 681  * calipso_pad_write - Writes pad bytes in TLV format
 682  * @buf: the buffer
 683  * @offset: offset from start of buffer to write padding
 684  * @count: number of pad bytes to write
 685  *
 686  * Description:
 687  * Write @count bytes of TLV padding into @buffer starting at offset @offset.
 688  * @count should be less than 8 - see RFC 4942.
 689  *
 690  */
 691 static int calipso_pad_write(unsigned char *buf, unsigned int offset,
 692                              unsigned int count)
 693 {
 694         if (WARN_ON_ONCE(count >= 8))
 695                 return -EINVAL;
 696 
 697         switch (count) {
 698         case 0:
 699                 break;
 700         case 1:
 701                 buf[offset] = IPV6_TLV_PAD1;
 702                 break;
 703         default:
 704                 buf[offset] = IPV6_TLV_PADN;
 705                 buf[offset + 1] = count - 2;
 706                 if (count > 2)
 707                         memset(buf + offset + 2, 0, count - 2);
 708                 break;
 709         }
 710         return 0;
 711 }
 712 
 713 /**
 714  * calipso_genopt - Generate a CALIPSO option
 715  * @buf: the option buffer
 716  * @start: offset from which to write
 717  * @buf_len: the size of opt_buf
 718  * @doi_def: the CALIPSO DOI to use
 719  * @secattr: the security attributes
 720  *
 721  * Description:
 722  * Generate a CALIPSO option using the DOI definition and security attributes
 723  * passed to the function. This also generates upto three bytes of leading
 724  * padding that ensures that the option is 4n + 2 aligned.  It returns the
 725  * number of bytes written (including any initial padding).
 726  */
 727 static int calipso_genopt(unsigned char *buf, u32 start, u32 buf_len,
 728                           const struct calipso_doi *doi_def,
 729                           const struct netlbl_lsm_secattr *secattr)
 730 {
 731         int ret_val;
 732         u32 len, pad;
 733         u16 crc;
 734         static const unsigned char padding[4] = {2, 1, 0, 3};
 735         unsigned char *calipso;
 736 
 737         /* CALIPSO has 4n + 2 alignment */
 738         pad = padding[start & 3];
 739         if (buf_len <= start + pad + CALIPSO_HDR_LEN)
 740                 return -ENOSPC;
 741 
 742         if ((secattr->flags & NETLBL_SECATTR_MLS_LVL) == 0)
 743                 return -EPERM;
 744 
 745         len = CALIPSO_HDR_LEN;
 746 
 747         if (secattr->flags & NETLBL_SECATTR_MLS_CAT) {
 748                 ret_val = calipso_map_cat_hton(doi_def,
 749                                                secattr,
 750                                                buf + start + pad + len,
 751                                                buf_len - start - pad - len);
 752                 if (ret_val < 0)
 753                         return ret_val;
 754                 len += ret_val;
 755         }
 756 
 757         calipso_pad_write(buf, start, pad);
 758         calipso = buf + start + pad;
 759 
 760         calipso[0] = IPV6_TLV_CALIPSO;
 761         calipso[1] = len - 2;
 762         *(__be32 *)(calipso + 2) = htonl(doi_def->doi);
 763         calipso[6] = (len - CALIPSO_HDR_LEN) / 4;
 764         calipso[7] = secattr->attr.mls.lvl,
 765         crc = ~crc_ccitt(0xffff, calipso, len);
 766         calipso[8] = crc & 0xff;
 767         calipso[9] = (crc >> 8) & 0xff;
 768         return pad + len;
 769 }
 770 
 771 /* Hop-by-hop hdr helper functions
 772  */
 773 
 774 /**
 775  * calipso_opt_update - Replaces socket's hop options with a new set
 776  * @sk: the socket
 777  * @hop: new hop options
 778  *
 779  * Description:
 780  * Replaces @sk's hop options with @hop.  @hop may be NULL to leave
 781  * the socket with no hop options.
 782  *
 783  */
 784 static int calipso_opt_update(struct sock *sk, struct ipv6_opt_hdr *hop)
 785 {
 786         struct ipv6_txoptions *old = txopt_get(inet6_sk(sk)), *txopts;
 787 
 788         txopts = ipv6_renew_options(sk, old, IPV6_HOPOPTS, hop);
 789         txopt_put(old);
 790         if (IS_ERR(txopts))
 791                 return PTR_ERR(txopts);
 792 
 793         txopts = ipv6_update_options(sk, txopts);
 794         if (txopts) {
 795                 atomic_sub(txopts->tot_len, &sk->sk_omem_alloc);
 796                 txopt_put(txopts);
 797         }
 798 
 799         return 0;
 800 }
 801 
 802 /**
 803  * calipso_tlv_len - Returns the length of the TLV
 804  * @opt: the option header
 805  * @offset: offset of the TLV within the header
 806  *
 807  * Description:
 808  * Returns the length of the TLV option at offset @offset within
 809  * the option header @opt.  Checks that the entire TLV fits inside
 810  * the option header, returns a negative value if this is not the case.
 811  */
 812 static int calipso_tlv_len(struct ipv6_opt_hdr *opt, unsigned int offset)
 813 {
 814         unsigned char *tlv = (unsigned char *)opt;
 815         unsigned int opt_len = ipv6_optlen(opt), tlv_len;
 816 
 817         if (offset < sizeof(*opt) || offset >= opt_len)
 818                 return -EINVAL;
 819         if (tlv[offset] == IPV6_TLV_PAD1)
 820                 return 1;
 821         if (offset + 1 >= opt_len)
 822                 return -EINVAL;
 823         tlv_len = tlv[offset + 1] + 2;
 824         if (offset + tlv_len > opt_len)
 825                 return -EINVAL;
 826         return tlv_len;
 827 }
 828 
 829 /**
 830  * calipso_opt_find - Finds the CALIPSO option in an IPv6 hop options header
 831  * @hop: the hop options header
 832  * @start: on return holds the offset of any leading padding
 833  * @end: on return holds the offset of the first non-pad TLV after CALIPSO
 834  *
 835  * Description:
 836  * Finds the space occupied by a CALIPSO option (including any leading and
 837  * trailing padding).
 838  *
 839  * If a CALIPSO option exists set @start and @end to the
 840  * offsets within @hop of the start of padding before the first
 841  * CALIPSO option and the end of padding after the first CALIPSO
 842  * option.  In this case the function returns 0.
 843  *
 844  * In the absence of a CALIPSO option, @start and @end will be
 845  * set to the start and end of any trailing padding in the header.
 846  * This is useful when appending a new option, as the caller may want
 847  * to overwrite some of this padding.  In this case the function will
 848  * return -ENOENT.
 849  */
 850 static int calipso_opt_find(struct ipv6_opt_hdr *hop, unsigned int *start,
 851                             unsigned int *end)
 852 {
 853         int ret_val = -ENOENT, tlv_len;
 854         unsigned int opt_len, offset, offset_s = 0, offset_e = 0;
 855         unsigned char *opt = (unsigned char *)hop;
 856 
 857         opt_len = ipv6_optlen(hop);
 858         offset = sizeof(*hop);
 859 
 860         while (offset < opt_len) {
 861                 tlv_len = calipso_tlv_len(hop, offset);
 862                 if (tlv_len < 0)
 863                         return tlv_len;
 864 
 865                 switch (opt[offset]) {
 866                 case IPV6_TLV_PAD1:
 867                 case IPV6_TLV_PADN:
 868                         if (offset_e)
 869                                 offset_e = offset;
 870                         break;
 871                 case IPV6_TLV_CALIPSO:
 872                         ret_val = 0;
 873                         offset_e = offset;
 874                         break;
 875                 default:
 876                         if (offset_e == 0)
 877                                 offset_s = offset;
 878                         else
 879                                 goto out;
 880                 }
 881                 offset += tlv_len;
 882         }
 883 
 884 out:
 885         if (offset_s)
 886                 *start = offset_s + calipso_tlv_len(hop, offset_s);
 887         else
 888                 *start = sizeof(*hop);
 889         if (offset_e)
 890                 *end = offset_e + calipso_tlv_len(hop, offset_e);
 891         else
 892                 *end = opt_len;
 893 
 894         return ret_val;
 895 }
 896 
 897 /**
 898  * calipso_opt_insert - Inserts a CALIPSO option into an IPv6 hop opt hdr
 899  * @hop: the original hop options header
 900  * @doi_def: the CALIPSO DOI to use
 901  * @secattr: the specific security attributes of the socket
 902  *
 903  * Description:
 904  * Creates a new hop options header based on @hop with a
 905  * CALIPSO option added to it.  If @hop already contains a CALIPSO
 906  * option this is overwritten, otherwise the new option is appended
 907  * after any existing options.  If @hop is NULL then the new header
 908  * will contain just the CALIPSO option and any needed padding.
 909  *
 910  */
 911 static struct ipv6_opt_hdr *
 912 calipso_opt_insert(struct ipv6_opt_hdr *hop,
 913                    const struct calipso_doi *doi_def,
 914                    const struct netlbl_lsm_secattr *secattr)
 915 {
 916         unsigned int start, end, buf_len, pad, hop_len;
 917         struct ipv6_opt_hdr *new;
 918         int ret_val;
 919 
 920         if (hop) {
 921                 hop_len = ipv6_optlen(hop);
 922                 ret_val = calipso_opt_find(hop, &start, &end);
 923                 if (ret_val && ret_val != -ENOENT)
 924                         return ERR_PTR(ret_val);
 925         } else {
 926                 hop_len = 0;
 927                 start = sizeof(*hop);
 928                 end = 0;
 929         }
 930 
 931         buf_len = hop_len + start - end + CALIPSO_OPT_LEN_MAX_WITH_PAD;
 932         new = kzalloc(buf_len, GFP_ATOMIC);
 933         if (!new)
 934                 return ERR_PTR(-ENOMEM);
 935 
 936         if (start > sizeof(*hop))
 937                 memcpy(new, hop, start);
 938         ret_val = calipso_genopt((unsigned char *)new, start, buf_len, doi_def,
 939                                  secattr);
 940         if (ret_val < 0) {
 941                 kfree(new);
 942                 return ERR_PTR(ret_val);
 943         }
 944 
 945         buf_len = start + ret_val;
 946         /* At this point buf_len aligns to 4n, so (buf_len & 4) pads to 8n */
 947         pad = ((buf_len & 4) + (end & 7)) & 7;
 948         calipso_pad_write((unsigned char *)new, buf_len, pad);
 949         buf_len += pad;
 950 
 951         if (end != hop_len) {
 952                 memcpy((char *)new + buf_len, (char *)hop + end, hop_len - end);
 953                 buf_len += hop_len - end;
 954         }
 955         new->nexthdr = 0;
 956         new->hdrlen = buf_len / 8 - 1;
 957 
 958         return new;
 959 }
 960 
 961 /**
 962  * calipso_opt_del - Removes the CALIPSO option from an option header
 963  * @hop: the original header
 964  * @new: the new header
 965  *
 966  * Description:
 967  * Creates a new header based on @hop without any CALIPSO option.  If @hop
 968  * doesn't contain a CALIPSO option it returns -ENOENT.  If @hop contains
 969  * no other non-padding options, it returns zero with @new set to NULL.
 970  * Otherwise it returns zero, creates a new header without the CALIPSO
 971  * option (and removing as much padding as possible) and returns with
 972  * @new set to that header.
 973  *
 974  */
 975 static int calipso_opt_del(struct ipv6_opt_hdr *hop,
 976                            struct ipv6_opt_hdr **new)
 977 {
 978         int ret_val;
 979         unsigned int start, end, delta, pad, hop_len;
 980 
 981         ret_val = calipso_opt_find(hop, &start, &end);
 982         if (ret_val)
 983                 return ret_val;
 984 
 985         hop_len = ipv6_optlen(hop);
 986         if (start == sizeof(*hop) && end == hop_len) {
 987                 /* There's no other option in the header so return NULL */
 988                 *new = NULL;
 989                 return 0;
 990         }
 991 
 992         delta = (end - start) & ~7;
 993         *new = kzalloc(hop_len - delta, GFP_ATOMIC);
 994         if (!*new)
 995                 return -ENOMEM;
 996 
 997         memcpy(*new, hop, start);
 998         (*new)->hdrlen -= delta / 8;
 999         pad = (end - start) & 7;
1000         calipso_pad_write((unsigned char *)*new, start, pad);
1001         if (end != hop_len)
1002                 memcpy((char *)*new + start + pad, (char *)hop + end,
1003                        hop_len - end);
1004 
1005         return 0;
1006 }
1007 
1008 /**
1009  * calipso_opt_getattr - Get the security attributes from a memory block
1010  * @calipso: the CALIPSO option
1011  * @secattr: the security attributes
1012  *
1013  * Description:
1014  * Inspect @calipso and return the security attributes in @secattr.
1015  * Returns zero on success and negative values on failure.
1016  *
1017  */
1018 static int calipso_opt_getattr(const unsigned char *calipso,
1019                                struct netlbl_lsm_secattr *secattr)
1020 {
1021         int ret_val = -ENOMSG;
1022         u32 doi, len = calipso[1], cat_len = calipso[6] * 4;
1023         struct calipso_doi *doi_def;
1024 
1025         if (cat_len + 8 > len)
1026                 return -EINVAL;
1027 
1028         if (calipso_cache_check(calipso + 2, calipso[1], secattr) == 0)
1029                 return 0;
1030 
1031         doi = get_unaligned_be32(calipso + 2);
1032         rcu_read_lock();
1033         doi_def = calipso_doi_search(doi);
1034         if (!doi_def)
1035                 goto getattr_return;
1036 
1037         secattr->attr.mls.lvl = calipso[7];
1038         secattr->flags |= NETLBL_SECATTR_MLS_LVL;
1039 
1040         if (cat_len) {
1041                 ret_val = calipso_map_cat_ntoh(doi_def,
1042                                                calipso + 10,
1043                                                cat_len,
1044                                                secattr);
1045                 if (ret_val != 0) {
1046                         netlbl_catmap_free(secattr->attr.mls.cat);
1047                         goto getattr_return;
1048                 }
1049 
1050                 if (secattr->attr.mls.cat)
1051                         secattr->flags |= NETLBL_SECATTR_MLS_CAT;
1052         }
1053 
1054         secattr->type = NETLBL_NLTYPE_CALIPSO;
1055 
1056 getattr_return:
1057         rcu_read_unlock();
1058         return ret_val;
1059 }
1060 
1061 /* sock functions.
1062  */
1063 
1064 /**
1065  * calipso_sock_getattr - Get the security attributes from a sock
1066  * @sk: the sock
1067  * @secattr: the security attributes
1068  *
1069  * Description:
1070  * Query @sk to see if there is a CALIPSO option attached to the sock and if
1071  * there is return the CALIPSO security attributes in @secattr.  This function
1072  * requires that @sk be locked, or privately held, but it does not do any
1073  * locking itself.  Returns zero on success and negative values on failure.
1074  *
1075  */
1076 static int calipso_sock_getattr(struct sock *sk,
1077                                 struct netlbl_lsm_secattr *secattr)
1078 {
1079         struct ipv6_opt_hdr *hop;
1080         int opt_len, len, ret_val = -ENOMSG, offset;
1081         unsigned char *opt;
1082         struct ipv6_txoptions *txopts = txopt_get(inet6_sk(sk));
1083 
1084         if (!txopts || !txopts->hopopt)
1085                 goto done;
1086 
1087         hop = txopts->hopopt;
1088         opt = (unsigned char *)hop;
1089         opt_len = ipv6_optlen(hop);
1090         offset = sizeof(*hop);
1091         while (offset < opt_len) {
1092                 len = calipso_tlv_len(hop, offset);
1093                 if (len < 0) {
1094                         ret_val = len;
1095                         goto done;
1096                 }
1097                 switch (opt[offset]) {
1098                 case IPV6_TLV_CALIPSO:
1099                         if (len < CALIPSO_HDR_LEN)
1100                                 ret_val = -EINVAL;
1101                         else
1102                                 ret_val = calipso_opt_getattr(&opt[offset],
1103                                                               secattr);
1104                         goto done;
1105                 default:
1106                         offset += len;
1107                         break;
1108                 }
1109         }
1110 done:
1111         txopt_put(txopts);
1112         return ret_val;
1113 }
1114 
1115 /**
1116  * calipso_sock_setattr - Add a CALIPSO option to a socket
1117  * @sk: the socket
1118  * @doi_def: the CALIPSO DOI to use
1119  * @secattr: the specific security attributes of the socket
1120  *
1121  * Description:
1122  * Set the CALIPSO option on the given socket using the DOI definition and
1123  * security attributes passed to the function.  This function requires
1124  * exclusive access to @sk, which means it either needs to be in the
1125  * process of being created or locked.  Returns zero on success and negative
1126  * values on failure.
1127  *
1128  */
1129 static int calipso_sock_setattr(struct sock *sk,
1130                                 const struct calipso_doi *doi_def,
1131                                 const struct netlbl_lsm_secattr *secattr)
1132 {
1133         int ret_val;
1134         struct ipv6_opt_hdr *old, *new;
1135         struct ipv6_txoptions *txopts = txopt_get(inet6_sk(sk));
1136 
1137         old = NULL;
1138         if (txopts)
1139                 old = txopts->hopopt;
1140 
1141         new = calipso_opt_insert(old, doi_def, secattr);
1142         txopt_put(txopts);
1143         if (IS_ERR(new))
1144                 return PTR_ERR(new);
1145 
1146         ret_val = calipso_opt_update(sk, new);
1147 
1148         kfree(new);
1149         return ret_val;
1150 }
1151 
1152 /**
1153  * calipso_sock_delattr - Delete the CALIPSO option from a socket
1154  * @sk: the socket
1155  *
1156  * Description:
1157  * Removes the CALIPSO option from a socket, if present.
1158  *
1159  */
1160 static void calipso_sock_delattr(struct sock *sk)
1161 {
1162         struct ipv6_opt_hdr *new_hop;
1163         struct ipv6_txoptions *txopts = txopt_get(inet6_sk(sk));
1164 
1165         if (!txopts || !txopts->hopopt)
1166                 goto done;
1167 
1168         if (calipso_opt_del(txopts->hopopt, &new_hop))
1169                 goto done;
1170 
1171         calipso_opt_update(sk, new_hop);
1172         kfree(new_hop);
1173 
1174 done:
1175         txopt_put(txopts);
1176 }
1177 
1178 /* request sock functions.
1179  */
1180 
1181 /**
1182  * calipso_req_setattr - Add a CALIPSO option to a connection request socket
1183  * @req: the connection request socket
1184  * @doi_def: the CALIPSO DOI to use
1185  * @secattr: the specific security attributes of the socket
1186  *
1187  * Description:
1188  * Set the CALIPSO option on the given socket using the DOI definition and
1189  * security attributes passed to the function.  Returns zero on success and
1190  * negative values on failure.
1191  *
1192  */
1193 static int calipso_req_setattr(struct request_sock *req,
1194                                const struct calipso_doi *doi_def,
1195                                const struct netlbl_lsm_secattr *secattr)
1196 {
1197         struct ipv6_txoptions *txopts;
1198         struct inet_request_sock *req_inet = inet_rsk(req);
1199         struct ipv6_opt_hdr *old, *new;
1200         struct sock *sk = sk_to_full_sk(req_to_sk(req));
1201 
1202         if (req_inet->ipv6_opt && req_inet->ipv6_opt->hopopt)
1203                 old = req_inet->ipv6_opt->hopopt;
1204         else
1205                 old = NULL;
1206 
1207         new = calipso_opt_insert(old, doi_def, secattr);
1208         if (IS_ERR(new))
1209                 return PTR_ERR(new);
1210 
1211         txopts = ipv6_renew_options(sk, req_inet->ipv6_opt, IPV6_HOPOPTS, new);
1212 
1213         kfree(new);
1214 
1215         if (IS_ERR(txopts))
1216                 return PTR_ERR(txopts);
1217 
1218         txopts = xchg(&req_inet->ipv6_opt, txopts);
1219         if (txopts) {
1220                 atomic_sub(txopts->tot_len, &sk->sk_omem_alloc);
1221                 txopt_put(txopts);
1222         }
1223 
1224         return 0;
1225 }
1226 
1227 /**
1228  * calipso_req_delattr - Delete the CALIPSO option from a request socket
1229  * @reg: the request socket
1230  *
1231  * Description:
1232  * Removes the CALIPSO option from a request socket, if present.
1233  *
1234  */
1235 static void calipso_req_delattr(struct request_sock *req)
1236 {
1237         struct inet_request_sock *req_inet = inet_rsk(req);
1238         struct ipv6_opt_hdr *new;
1239         struct ipv6_txoptions *txopts;
1240         struct sock *sk = sk_to_full_sk(req_to_sk(req));
1241 
1242         if (!req_inet->ipv6_opt || !req_inet->ipv6_opt->hopopt)
1243                 return;
1244 
1245         if (calipso_opt_del(req_inet->ipv6_opt->hopopt, &new))
1246                 return; /* Nothing to do */
1247 
1248         txopts = ipv6_renew_options(sk, req_inet->ipv6_opt, IPV6_HOPOPTS, new);
1249 
1250         if (!IS_ERR(txopts)) {
1251                 txopts = xchg(&req_inet->ipv6_opt, txopts);
1252                 if (txopts) {
1253                         atomic_sub(txopts->tot_len, &sk->sk_omem_alloc);
1254                         txopt_put(txopts);
1255                 }
1256         }
1257         kfree(new);
1258 }
1259 
1260 /* skbuff functions.
1261  */
1262 
1263 /**
1264  * calipso_skbuff_optptr - Find the CALIPSO option in the packet
1265  * @skb: the packet
1266  *
1267  * Description:
1268  * Parse the packet's IP header looking for a CALIPSO option.  Returns a pointer
1269  * to the start of the CALIPSO option on success, NULL if one if not found.
1270  *
1271  */
1272 static unsigned char *calipso_skbuff_optptr(const struct sk_buff *skb)
1273 {
1274         const struct ipv6hdr *ip6_hdr = ipv6_hdr(skb);
1275         int offset;
1276 
1277         if (ip6_hdr->nexthdr != NEXTHDR_HOP)
1278                 return NULL;
1279 
1280         offset = ipv6_find_tlv(skb, sizeof(*ip6_hdr), IPV6_TLV_CALIPSO);
1281         if (offset >= 0)
1282                 return (unsigned char *)ip6_hdr + offset;
1283 
1284         return NULL;
1285 }
1286 
1287 /**
1288  * calipso_skbuff_setattr - Set the CALIPSO option on a packet
1289  * @skb: the packet
1290  * @doi_def: the CALIPSO DOI to use
1291  * @secattr: the security attributes
1292  *
1293  * Description:
1294  * Set the CALIPSO option on the given packet based on the security attributes.
1295  * Returns a pointer to the IP header on success and NULL on failure.
1296  *
1297  */
1298 static int calipso_skbuff_setattr(struct sk_buff *skb,
1299                                   const struct calipso_doi *doi_def,
1300                                   const struct netlbl_lsm_secattr *secattr)
1301 {
1302         int ret_val;
1303         struct ipv6hdr *ip6_hdr;
1304         struct ipv6_opt_hdr *hop;
1305         unsigned char buf[CALIPSO_MAX_BUFFER];
1306         int len_delta, new_end, pad, payload;
1307         unsigned int start, end;
1308 
1309         ip6_hdr = ipv6_hdr(skb);
1310         if (ip6_hdr->nexthdr == NEXTHDR_HOP) {
1311                 hop = (struct ipv6_opt_hdr *)(ip6_hdr + 1);
1312                 ret_val = calipso_opt_find(hop, &start, &end);
1313                 if (ret_val && ret_val != -ENOENT)
1314                         return ret_val;
1315         } else {
1316                 start = 0;
1317                 end = 0;
1318         }
1319 
1320         memset(buf, 0, sizeof(buf));
1321         ret_val = calipso_genopt(buf, start & 3, sizeof(buf), doi_def, secattr);
1322         if (ret_val < 0)
1323                 return ret_val;
1324 
1325         new_end = start + ret_val;
1326         /* At this point new_end aligns to 4n, so (new_end & 4) pads to 8n */
1327         pad = ((new_end & 4) + (end & 7)) & 7;
1328         len_delta = new_end - (int)end + pad;
1329         ret_val = skb_cow(skb, skb_headroom(skb) + len_delta);
1330         if (ret_val < 0)
1331                 return ret_val;
1332 
1333         ip6_hdr = ipv6_hdr(skb); /* Reset as skb_cow() may have moved it */
1334 
1335         if (len_delta) {
1336                 if (len_delta > 0)
1337                         skb_push(skb, len_delta);
1338                 else
1339                         skb_pull(skb, -len_delta);
1340                 memmove((char *)ip6_hdr - len_delta, ip6_hdr,
1341                         sizeof(*ip6_hdr) + start);
1342                 skb_reset_network_header(skb);
1343                 ip6_hdr = ipv6_hdr(skb);
1344                 payload = ntohs(ip6_hdr->payload_len);
1345                 ip6_hdr->payload_len = htons(payload + len_delta);
1346         }
1347 
1348         hop = (struct ipv6_opt_hdr *)(ip6_hdr + 1);
1349         if (start == 0) {
1350                 struct ipv6_opt_hdr *new_hop = (struct ipv6_opt_hdr *)buf;
1351 
1352                 new_hop->nexthdr = ip6_hdr->nexthdr;
1353                 new_hop->hdrlen = len_delta / 8 - 1;
1354                 ip6_hdr->nexthdr = NEXTHDR_HOP;
1355         } else {
1356                 hop->hdrlen += len_delta / 8;
1357         }
1358         memcpy((char *)hop + start, buf + (start & 3), new_end - start);
1359         calipso_pad_write((unsigned char *)hop, new_end, pad);
1360 
1361         return 0;
1362 }
1363 
1364 /**
1365  * calipso_skbuff_delattr - Delete any CALIPSO options from a packet
1366  * @skb: the packet
1367  *
1368  * Description:
1369  * Removes any and all CALIPSO options from the given packet.  Returns zero on
1370  * success, negative values on failure.
1371  *
1372  */
1373 static int calipso_skbuff_delattr(struct sk_buff *skb)
1374 {
1375         int ret_val;
1376         struct ipv6hdr *ip6_hdr;
1377         struct ipv6_opt_hdr *old_hop;
1378         u32 old_hop_len, start = 0, end = 0, delta, size, pad;
1379 
1380         if (!calipso_skbuff_optptr(skb))
1381                 return 0;
1382 
1383         /* since we are changing the packet we should make a copy */
1384         ret_val = skb_cow(skb, skb_headroom(skb));
1385         if (ret_val < 0)
1386                 return ret_val;
1387 
1388         ip6_hdr = ipv6_hdr(skb);
1389         old_hop = (struct ipv6_opt_hdr *)(ip6_hdr + 1);
1390         old_hop_len = ipv6_optlen(old_hop);
1391 
1392         ret_val = calipso_opt_find(old_hop, &start, &end);
1393         if (ret_val)
1394                 return ret_val;
1395 
1396         if (start == sizeof(*old_hop) && end == old_hop_len) {
1397                 /* There's no other option in the header so we delete
1398                  * the whole thing. */
1399                 delta = old_hop_len;
1400                 size = sizeof(*ip6_hdr);
1401                 ip6_hdr->nexthdr = old_hop->nexthdr;
1402         } else {
1403                 delta = (end - start) & ~7;
1404                 if (delta)
1405                         old_hop->hdrlen -= delta / 8;
1406                 pad = (end - start) & 7;
1407                 size = sizeof(*ip6_hdr) + start + pad;
1408                 calipso_pad_write((unsigned char *)old_hop, start, pad);
1409         }
1410 
1411         if (delta) {
1412                 skb_pull(skb, delta);
1413                 memmove((char *)ip6_hdr + delta, ip6_hdr, size);
1414                 skb_reset_network_header(skb);
1415         }
1416 
1417         return 0;
1418 }
1419 
1420 static const struct netlbl_calipso_ops ops = {
1421         .doi_add          = calipso_doi_add,
1422         .doi_free         = calipso_doi_free,
1423         .doi_remove       = calipso_doi_remove,
1424         .doi_getdef       = calipso_doi_getdef,
1425         .doi_putdef       = calipso_doi_putdef,
1426         .doi_walk         = calipso_doi_walk,
1427         .sock_getattr     = calipso_sock_getattr,
1428         .sock_setattr     = calipso_sock_setattr,
1429         .sock_delattr     = calipso_sock_delattr,
1430         .req_setattr      = calipso_req_setattr,
1431         .req_delattr      = calipso_req_delattr,
1432         .opt_getattr      = calipso_opt_getattr,
1433         .skbuff_optptr    = calipso_skbuff_optptr,
1434         .skbuff_setattr   = calipso_skbuff_setattr,
1435         .skbuff_delattr   = calipso_skbuff_delattr,
1436         .cache_invalidate = calipso_cache_invalidate,
1437         .cache_add        = calipso_cache_add
1438 };
1439 
1440 /**
1441  * calipso_init - Initialize the CALIPSO module
1442  *
1443  * Description:
1444  * Initialize the CALIPSO module and prepare it for use.  Returns zero on
1445  * success and negative values on failure.
1446  *
1447  */
1448 int __init calipso_init(void)
1449 {
1450         int ret_val;
1451 
1452         ret_val = calipso_cache_init();
1453         if (!ret_val)
1454                 netlbl_calipso_ops_register(&ops);
1455         return ret_val;
1456 }
1457 
1458 void calipso_exit(void)
1459 {
1460         netlbl_calipso_ops_register(NULL);
1461         calipso_cache_invalidate();
1462         kfree(calipso_cache);
1463 }