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Linux/net/ipv4/cipso_ipv4.c

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  1 /*
  2  * CIPSO - Commercial IP Security Option
  3  *
  4  * This is an implementation of the CIPSO 2.2 protocol as specified in
  5  * draft-ietf-cipso-ipsecurity-01.txt with additional tag types as found in
  6  * FIPS-188.  While CIPSO never became a full IETF RFC standard many vendors
  7  * have chosen to adopt the protocol and over the years it has become a
  8  * de-facto standard for labeled networking.
  9  *
 10  * The CIPSO draft specification can be found in the kernel's Documentation
 11  * directory as well as the following URL:
 12  *   http://tools.ietf.org/id/draft-ietf-cipso-ipsecurity-01.txt
 13  * The FIPS-188 specification can be found at the following URL:
 14  *   http://www.itl.nist.gov/fipspubs/fip188.htm
 15  *
 16  * Author: Paul Moore <paul.moore@hp.com>
 17  *
 18  */
 19 
 20 /*
 21  * (c) Copyright Hewlett-Packard Development Company, L.P., 2006, 2008
 22  *
 23  * This program is free software;  you can redistribute it and/or modify
 24  * it under the terms of the GNU General Public License as published by
 25  * the Free Software Foundation; either version 2 of the License, or
 26  * (at your option) any later version.
 27  *
 28  * This program is distributed in the hope that it will be useful,
 29  * but WITHOUT ANY WARRANTY;  without even the implied warranty of
 30  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 31  * the GNU General Public License for more details.
 32  *
 33  * You should have received a copy of the GNU General Public License
 34  * along with this program;  if not, see <http://www.gnu.org/licenses/>.
 35  *
 36  */
 37 
 38 #include <linux/init.h>
 39 #include <linux/types.h>
 40 #include <linux/rcupdate.h>
 41 #include <linux/list.h>
 42 #include <linux/spinlock.h>
 43 #include <linux/string.h>
 44 #include <linux/jhash.h>
 45 #include <linux/audit.h>
 46 #include <linux/slab.h>
 47 #include <net/ip.h>
 48 #include <net/icmp.h>
 49 #include <net/tcp.h>
 50 #include <net/netlabel.h>
 51 #include <net/cipso_ipv4.h>
 52 #include <linux/atomic.h>
 53 #include <asm/bug.h>
 54 #include <asm/unaligned.h>
 55 
 56 /* List of available DOI definitions */
 57 /* XXX - This currently assumes a minimal number of different DOIs in use,
 58  * if in practice there are a lot of different DOIs this list should
 59  * probably be turned into a hash table or something similar so we
 60  * can do quick lookups. */
 61 static DEFINE_SPINLOCK(cipso_v4_doi_list_lock);
 62 static LIST_HEAD(cipso_v4_doi_list);
 63 
 64 /* Label mapping cache */
 65 int cipso_v4_cache_enabled = 1;
 66 int cipso_v4_cache_bucketsize = 10;
 67 #define CIPSO_V4_CACHE_BUCKETBITS     7
 68 #define CIPSO_V4_CACHE_BUCKETS        (1 << CIPSO_V4_CACHE_BUCKETBITS)
 69 #define CIPSO_V4_CACHE_REORDERLIMIT   10
 70 struct cipso_v4_map_cache_bkt {
 71         spinlock_t lock;
 72         u32 size;
 73         struct list_head list;
 74 };
 75 struct cipso_v4_map_cache_entry {
 76         u32 hash;
 77         unsigned char *key;
 78         size_t key_len;
 79 
 80         struct netlbl_lsm_cache *lsm_data;
 81 
 82         u32 activity;
 83         struct list_head list;
 84 };
 85 static struct cipso_v4_map_cache_bkt *cipso_v4_cache = NULL;
 86 
 87 /* Restricted bitmap (tag #1) flags */
 88 int cipso_v4_rbm_optfmt = 0;
 89 int cipso_v4_rbm_strictvalid = 1;
 90 
 91 /*
 92  * Protocol Constants
 93  */
 94 
 95 /* Maximum size of the CIPSO IP option, derived from the fact that the maximum
 96  * IPv4 header size is 60 bytes and the base IPv4 header is 20 bytes long. */
 97 #define CIPSO_V4_OPT_LEN_MAX          40
 98 
 99 /* Length of the base CIPSO option, this includes the option type (1 byte), the
100  * option length (1 byte), and the DOI (4 bytes). */
101 #define CIPSO_V4_HDR_LEN              6
102 
103 /* Base length of the restrictive category bitmap tag (tag #1). */
104 #define CIPSO_V4_TAG_RBM_BLEN         4
105 
106 /* Base length of the enumerated category tag (tag #2). */
107 #define CIPSO_V4_TAG_ENUM_BLEN        4
108 
109 /* Base length of the ranged categories bitmap tag (tag #5). */
110 #define CIPSO_V4_TAG_RNG_BLEN         4
111 /* The maximum number of category ranges permitted in the ranged category tag
112  * (tag #5).  You may note that the IETF draft states that the maximum number
113  * of category ranges is 7, but if the low end of the last category range is
114  * zero then it is possible to fit 8 category ranges because the zero should
115  * be omitted. */
116 #define CIPSO_V4_TAG_RNG_CAT_MAX      8
117 
118 /* Base length of the local tag (non-standard tag).
119  *  Tag definition (may change between kernel versions)
120  *
121  * 0          8          16         24         32
122  * +----------+----------+----------+----------+
123  * | 10000000 | 00000110 | 32-bit secid value  |
124  * +----------+----------+----------+----------+
125  * | in (host byte order)|
126  * +----------+----------+
127  *
128  */
129 #define CIPSO_V4_TAG_LOC_BLEN         6
130 
131 /*
132  * Helper Functions
133  */
134 
135 /**
136  * cipso_v4_bitmap_walk - Walk a bitmap looking for a bit
137  * @bitmap: the bitmap
138  * @bitmap_len: length in bits
139  * @offset: starting offset
140  * @state: if non-zero, look for a set (1) bit else look for a cleared (0) bit
141  *
142  * Description:
143  * Starting at @offset, walk the bitmap from left to right until either the
144  * desired bit is found or we reach the end.  Return the bit offset, -1 if
145  * not found, or -2 if error.
146  */
147 static int cipso_v4_bitmap_walk(const unsigned char *bitmap,
148                                 u32 bitmap_len,
149                                 u32 offset,
150                                 u8 state)
151 {
152         u32 bit_spot;
153         u32 byte_offset;
154         unsigned char bitmask;
155         unsigned char byte;
156 
157         /* gcc always rounds to zero when doing integer division */
158         byte_offset = offset / 8;
159         byte = bitmap[byte_offset];
160         bit_spot = offset;
161         bitmask = 0x80 >> (offset % 8);
162 
163         while (bit_spot < bitmap_len) {
164                 if ((state && (byte & bitmask) == bitmask) ||
165                     (state == 0 && (byte & bitmask) == 0))
166                         return bit_spot;
167 
168                 if (++bit_spot >= bitmap_len)
169                         return -1;
170                 bitmask >>= 1;
171                 if (bitmask == 0) {
172                         byte = bitmap[++byte_offset];
173                         bitmask = 0x80;
174                 }
175         }
176 
177         return -1;
178 }
179 
180 /**
181  * cipso_v4_bitmap_setbit - Sets a single bit in a bitmap
182  * @bitmap: the bitmap
183  * @bit: the bit
184  * @state: if non-zero, set the bit (1) else clear the bit (0)
185  *
186  * Description:
187  * Set a single bit in the bitmask.  Returns zero on success, negative values
188  * on error.
189  */
190 static void cipso_v4_bitmap_setbit(unsigned char *bitmap,
191                                    u32 bit,
192                                    u8 state)
193 {
194         u32 byte_spot;
195         u8 bitmask;
196 
197         /* gcc always rounds to zero when doing integer division */
198         byte_spot = bit / 8;
199         bitmask = 0x80 >> (bit % 8);
200         if (state)
201                 bitmap[byte_spot] |= bitmask;
202         else
203                 bitmap[byte_spot] &= ~bitmask;
204 }
205 
206 /**
207  * cipso_v4_cache_entry_free - Frees a cache entry
208  * @entry: the entry to free
209  *
210  * Description:
211  * This function frees the memory associated with a cache entry including the
212  * LSM cache data if there are no longer any users, i.e. reference count == 0.
213  *
214  */
215 static void cipso_v4_cache_entry_free(struct cipso_v4_map_cache_entry *entry)
216 {
217         if (entry->lsm_data)
218                 netlbl_secattr_cache_free(entry->lsm_data);
219         kfree(entry->key);
220         kfree(entry);
221 }
222 
223 /**
224  * cipso_v4_map_cache_hash - Hashing function for the CIPSO cache
225  * @key: the hash key
226  * @key_len: the length of the key in bytes
227  *
228  * Description:
229  * The CIPSO tag hashing function.  Returns a 32-bit hash value.
230  *
231  */
232 static u32 cipso_v4_map_cache_hash(const unsigned char *key, u32 key_len)
233 {
234         return jhash(key, key_len, 0);
235 }
236 
237 /*
238  * Label Mapping Cache Functions
239  */
240 
241 /**
242  * cipso_v4_cache_init - Initialize the CIPSO cache
243  *
244  * Description:
245  * Initializes the CIPSO label mapping cache, this function should be called
246  * before any of the other functions defined in this file.  Returns zero on
247  * success, negative values on error.
248  *
249  */
250 static int __init cipso_v4_cache_init(void)
251 {
252         u32 iter;
253 
254         cipso_v4_cache = kcalloc(CIPSO_V4_CACHE_BUCKETS,
255                                  sizeof(struct cipso_v4_map_cache_bkt),
256                                  GFP_KERNEL);
257         if (cipso_v4_cache == NULL)
258                 return -ENOMEM;
259 
260         for (iter = 0; iter < CIPSO_V4_CACHE_BUCKETS; iter++) {
261                 spin_lock_init(&cipso_v4_cache[iter].lock);
262                 cipso_v4_cache[iter].size = 0;
263                 INIT_LIST_HEAD(&cipso_v4_cache[iter].list);
264         }
265 
266         return 0;
267 }
268 
269 /**
270  * cipso_v4_cache_invalidate - Invalidates the current CIPSO cache
271  *
272  * Description:
273  * Invalidates and frees any entries in the CIPSO cache.  Returns zero on
274  * success and negative values on failure.
275  *
276  */
277 void cipso_v4_cache_invalidate(void)
278 {
279         struct cipso_v4_map_cache_entry *entry, *tmp_entry;
280         u32 iter;
281 
282         for (iter = 0; iter < CIPSO_V4_CACHE_BUCKETS; iter++) {
283                 spin_lock_bh(&cipso_v4_cache[iter].lock);
284                 list_for_each_entry_safe(entry,
285                                          tmp_entry,
286                                          &cipso_v4_cache[iter].list, list) {
287                         list_del(&entry->list);
288                         cipso_v4_cache_entry_free(entry);
289                 }
290                 cipso_v4_cache[iter].size = 0;
291                 spin_unlock_bh(&cipso_v4_cache[iter].lock);
292         }
293 }
294 
295 /**
296  * cipso_v4_cache_check - Check the CIPSO cache for a label mapping
297  * @key: the buffer to check
298  * @key_len: buffer length in bytes
299  * @secattr: the security attribute struct to use
300  *
301  * Description:
302  * This function checks the cache to see if a label mapping already exists for
303  * the given key.  If there is a match then the cache is adjusted and the
304  * @secattr struct is populated with the correct LSM security attributes.  The
305  * cache is adjusted in the following manner if the entry is not already the
306  * first in the cache bucket:
307  *
308  *  1. The cache entry's activity counter is incremented
309  *  2. The previous (higher ranking) entry's activity counter is decremented
310  *  3. If the difference between the two activity counters is geater than
311  *     CIPSO_V4_CACHE_REORDERLIMIT the two entries are swapped
312  *
313  * Returns zero on success, -ENOENT for a cache miss, and other negative values
314  * on error.
315  *
316  */
317 static int cipso_v4_cache_check(const unsigned char *key,
318                                 u32 key_len,
319                                 struct netlbl_lsm_secattr *secattr)
320 {
321         u32 bkt;
322         struct cipso_v4_map_cache_entry *entry;
323         struct cipso_v4_map_cache_entry *prev_entry = NULL;
324         u32 hash;
325 
326         if (!cipso_v4_cache_enabled)
327                 return -ENOENT;
328 
329         hash = cipso_v4_map_cache_hash(key, key_len);
330         bkt = hash & (CIPSO_V4_CACHE_BUCKETS - 1);
331         spin_lock_bh(&cipso_v4_cache[bkt].lock);
332         list_for_each_entry(entry, &cipso_v4_cache[bkt].list, list) {
333                 if (entry->hash == hash &&
334                     entry->key_len == key_len &&
335                     memcmp(entry->key, key, key_len) == 0) {
336                         entry->activity += 1;
337                         atomic_inc(&entry->lsm_data->refcount);
338                         secattr->cache = entry->lsm_data;
339                         secattr->flags |= NETLBL_SECATTR_CACHE;
340                         secattr->type = NETLBL_NLTYPE_CIPSOV4;
341                         if (prev_entry == NULL) {
342                                 spin_unlock_bh(&cipso_v4_cache[bkt].lock);
343                                 return 0;
344                         }
345 
346                         if (prev_entry->activity > 0)
347                                 prev_entry->activity -= 1;
348                         if (entry->activity > prev_entry->activity &&
349                             entry->activity - prev_entry->activity >
350                             CIPSO_V4_CACHE_REORDERLIMIT) {
351                                 __list_del(entry->list.prev, entry->list.next);
352                                 __list_add(&entry->list,
353                                            prev_entry->list.prev,
354                                            &prev_entry->list);
355                         }
356 
357                         spin_unlock_bh(&cipso_v4_cache[bkt].lock);
358                         return 0;
359                 }
360                 prev_entry = entry;
361         }
362         spin_unlock_bh(&cipso_v4_cache[bkt].lock);
363 
364         return -ENOENT;
365 }
366 
367 /**
368  * cipso_v4_cache_add - Add an entry to the CIPSO cache
369  * @skb: the packet
370  * @secattr: the packet's security attributes
371  *
372  * Description:
373  * Add a new entry into the CIPSO label mapping cache.  Add the new entry to
374  * head of the cache bucket's list, if the cache bucket is out of room remove
375  * the last entry in the list first.  It is important to note that there is
376  * currently no checking for duplicate keys.  Returns zero on success,
377  * negative values on failure.
378  *
379  */
380 int cipso_v4_cache_add(const unsigned char *cipso_ptr,
381                        const struct netlbl_lsm_secattr *secattr)
382 {
383         int ret_val = -EPERM;
384         u32 bkt;
385         struct cipso_v4_map_cache_entry *entry = NULL;
386         struct cipso_v4_map_cache_entry *old_entry = NULL;
387         u32 cipso_ptr_len;
388 
389         if (!cipso_v4_cache_enabled || cipso_v4_cache_bucketsize <= 0)
390                 return 0;
391 
392         cipso_ptr_len = cipso_ptr[1];
393 
394         entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
395         if (entry == NULL)
396                 return -ENOMEM;
397         entry->key = kmemdup(cipso_ptr, cipso_ptr_len, GFP_ATOMIC);
398         if (entry->key == NULL) {
399                 ret_val = -ENOMEM;
400                 goto cache_add_failure;
401         }
402         entry->key_len = cipso_ptr_len;
403         entry->hash = cipso_v4_map_cache_hash(cipso_ptr, cipso_ptr_len);
404         atomic_inc(&secattr->cache->refcount);
405         entry->lsm_data = secattr->cache;
406 
407         bkt = entry->hash & (CIPSO_V4_CACHE_BUCKETS - 1);
408         spin_lock_bh(&cipso_v4_cache[bkt].lock);
409         if (cipso_v4_cache[bkt].size < cipso_v4_cache_bucketsize) {
410                 list_add(&entry->list, &cipso_v4_cache[bkt].list);
411                 cipso_v4_cache[bkt].size += 1;
412         } else {
413                 old_entry = list_entry(cipso_v4_cache[bkt].list.prev,
414                                        struct cipso_v4_map_cache_entry, list);
415                 list_del(&old_entry->list);
416                 list_add(&entry->list, &cipso_v4_cache[bkt].list);
417                 cipso_v4_cache_entry_free(old_entry);
418         }
419         spin_unlock_bh(&cipso_v4_cache[bkt].lock);
420 
421         return 0;
422 
423 cache_add_failure:
424         if (entry)
425                 cipso_v4_cache_entry_free(entry);
426         return ret_val;
427 }
428 
429 /*
430  * DOI List Functions
431  */
432 
433 /**
434  * cipso_v4_doi_search - Searches for a DOI definition
435  * @doi: the DOI to search for
436  *
437  * Description:
438  * Search the DOI definition list for a DOI definition with a DOI value that
439  * matches @doi.  The caller is responsible for calling rcu_read_[un]lock().
440  * Returns a pointer to the DOI definition on success and NULL on failure.
441  */
442 static struct cipso_v4_doi *cipso_v4_doi_search(u32 doi)
443 {
444         struct cipso_v4_doi *iter;
445 
446         list_for_each_entry_rcu(iter, &cipso_v4_doi_list, list)
447                 if (iter->doi == doi && atomic_read(&iter->refcount))
448                         return iter;
449         return NULL;
450 }
451 
452 /**
453  * cipso_v4_doi_add - Add a new DOI to the CIPSO protocol engine
454  * @doi_def: the DOI structure
455  * @audit_info: NetLabel audit information
456  *
457  * Description:
458  * The caller defines a new DOI for use by the CIPSO engine and calls this
459  * function to add it to the list of acceptable domains.  The caller must
460  * ensure that the mapping table specified in @doi_def->map meets all of the
461  * requirements of the mapping type (see cipso_ipv4.h for details).  Returns
462  * zero on success and non-zero on failure.
463  *
464  */
465 int cipso_v4_doi_add(struct cipso_v4_doi *doi_def,
466                      struct netlbl_audit *audit_info)
467 {
468         int ret_val = -EINVAL;
469         u32 iter;
470         u32 doi;
471         u32 doi_type;
472         struct audit_buffer *audit_buf;
473 
474         doi = doi_def->doi;
475         doi_type = doi_def->type;
476 
477         if (doi_def->doi == CIPSO_V4_DOI_UNKNOWN)
478                 goto doi_add_return;
479         for (iter = 0; iter < CIPSO_V4_TAG_MAXCNT; iter++) {
480                 switch (doi_def->tags[iter]) {
481                 case CIPSO_V4_TAG_RBITMAP:
482                         break;
483                 case CIPSO_V4_TAG_RANGE:
484                 case CIPSO_V4_TAG_ENUM:
485                         if (doi_def->type != CIPSO_V4_MAP_PASS)
486                                 goto doi_add_return;
487                         break;
488                 case CIPSO_V4_TAG_LOCAL:
489                         if (doi_def->type != CIPSO_V4_MAP_LOCAL)
490                                 goto doi_add_return;
491                         break;
492                 case CIPSO_V4_TAG_INVALID:
493                         if (iter == 0)
494                                 goto doi_add_return;
495                         break;
496                 default:
497                         goto doi_add_return;
498                 }
499         }
500 
501         atomic_set(&doi_def->refcount, 1);
502 
503         spin_lock(&cipso_v4_doi_list_lock);
504         if (cipso_v4_doi_search(doi_def->doi) != NULL) {
505                 spin_unlock(&cipso_v4_doi_list_lock);
506                 ret_val = -EEXIST;
507                 goto doi_add_return;
508         }
509         list_add_tail_rcu(&doi_def->list, &cipso_v4_doi_list);
510         spin_unlock(&cipso_v4_doi_list_lock);
511         ret_val = 0;
512 
513 doi_add_return:
514         audit_buf = netlbl_audit_start(AUDIT_MAC_CIPSOV4_ADD, audit_info);
515         if (audit_buf != NULL) {
516                 const char *type_str;
517                 switch (doi_type) {
518                 case CIPSO_V4_MAP_TRANS:
519                         type_str = "trans";
520                         break;
521                 case CIPSO_V4_MAP_PASS:
522                         type_str = "pass";
523                         break;
524                 case CIPSO_V4_MAP_LOCAL:
525                         type_str = "local";
526                         break;
527                 default:
528                         type_str = "(unknown)";
529                 }
530                 audit_log_format(audit_buf,
531                                  " cipso_doi=%u cipso_type=%s res=%u",
532                                  doi, type_str, ret_val == 0 ? 1 : 0);
533                 audit_log_end(audit_buf);
534         }
535 
536         return ret_val;
537 }
538 
539 /**
540  * cipso_v4_doi_free - Frees a DOI definition
541  * @entry: the entry's RCU field
542  *
543  * Description:
544  * This function frees all of the memory associated with a DOI definition.
545  *
546  */
547 void cipso_v4_doi_free(struct cipso_v4_doi *doi_def)
548 {
549         if (doi_def == NULL)
550                 return;
551 
552         switch (doi_def->type) {
553         case CIPSO_V4_MAP_TRANS:
554                 kfree(doi_def->map.std->lvl.cipso);
555                 kfree(doi_def->map.std->lvl.local);
556                 kfree(doi_def->map.std->cat.cipso);
557                 kfree(doi_def->map.std->cat.local);
558                 break;
559         }
560         kfree(doi_def);
561 }
562 
563 /**
564  * cipso_v4_doi_free_rcu - Frees a DOI definition via the RCU pointer
565  * @entry: the entry's RCU field
566  *
567  * Description:
568  * This function is designed to be used as a callback to the call_rcu()
569  * function so that the memory allocated to the DOI definition can be released
570  * safely.
571  *
572  */
573 static void cipso_v4_doi_free_rcu(struct rcu_head *entry)
574 {
575         struct cipso_v4_doi *doi_def;
576 
577         doi_def = container_of(entry, struct cipso_v4_doi, rcu);
578         cipso_v4_doi_free(doi_def);
579 }
580 
581 /**
582  * cipso_v4_doi_remove - Remove an existing DOI from the CIPSO protocol engine
583  * @doi: the DOI value
584  * @audit_secid: the LSM secid to use in the audit message
585  *
586  * Description:
587  * Removes a DOI definition from the CIPSO engine.  The NetLabel routines will
588  * be called to release their own LSM domain mappings as well as our own
589  * domain list.  Returns zero on success and negative values on failure.
590  *
591  */
592 int cipso_v4_doi_remove(u32 doi, struct netlbl_audit *audit_info)
593 {
594         int ret_val;
595         struct cipso_v4_doi *doi_def;
596         struct audit_buffer *audit_buf;
597 
598         spin_lock(&cipso_v4_doi_list_lock);
599         doi_def = cipso_v4_doi_search(doi);
600         if (doi_def == NULL) {
601                 spin_unlock(&cipso_v4_doi_list_lock);
602                 ret_val = -ENOENT;
603                 goto doi_remove_return;
604         }
605         if (!atomic_dec_and_test(&doi_def->refcount)) {
606                 spin_unlock(&cipso_v4_doi_list_lock);
607                 ret_val = -EBUSY;
608                 goto doi_remove_return;
609         }
610         list_del_rcu(&doi_def->list);
611         spin_unlock(&cipso_v4_doi_list_lock);
612 
613         cipso_v4_cache_invalidate();
614         call_rcu(&doi_def->rcu, cipso_v4_doi_free_rcu);
615         ret_val = 0;
616 
617 doi_remove_return:
618         audit_buf = netlbl_audit_start(AUDIT_MAC_CIPSOV4_DEL, audit_info);
619         if (audit_buf != NULL) {
620                 audit_log_format(audit_buf,
621                                  " cipso_doi=%u res=%u",
622                                  doi, ret_val == 0 ? 1 : 0);
623                 audit_log_end(audit_buf);
624         }
625 
626         return ret_val;
627 }
628 
629 /**
630  * cipso_v4_doi_getdef - Returns a reference to a valid DOI definition
631  * @doi: the DOI value
632  *
633  * Description:
634  * Searches for a valid DOI definition and if one is found it is returned to
635  * the caller.  Otherwise NULL is returned.  The caller must ensure that
636  * rcu_read_lock() is held while accessing the returned definition and the DOI
637  * definition reference count is decremented when the caller is done.
638  *
639  */
640 struct cipso_v4_doi *cipso_v4_doi_getdef(u32 doi)
641 {
642         struct cipso_v4_doi *doi_def;
643 
644         rcu_read_lock();
645         doi_def = cipso_v4_doi_search(doi);
646         if (doi_def == NULL)
647                 goto doi_getdef_return;
648         if (!atomic_inc_not_zero(&doi_def->refcount))
649                 doi_def = NULL;
650 
651 doi_getdef_return:
652         rcu_read_unlock();
653         return doi_def;
654 }
655 
656 /**
657  * cipso_v4_doi_putdef - Releases a reference for the given DOI definition
658  * @doi_def: the DOI definition
659  *
660  * Description:
661  * Releases a DOI definition reference obtained from cipso_v4_doi_getdef().
662  *
663  */
664 void cipso_v4_doi_putdef(struct cipso_v4_doi *doi_def)
665 {
666         if (doi_def == NULL)
667                 return;
668 
669         if (!atomic_dec_and_test(&doi_def->refcount))
670                 return;
671         spin_lock(&cipso_v4_doi_list_lock);
672         list_del_rcu(&doi_def->list);
673         spin_unlock(&cipso_v4_doi_list_lock);
674 
675         cipso_v4_cache_invalidate();
676         call_rcu(&doi_def->rcu, cipso_v4_doi_free_rcu);
677 }
678 
679 /**
680  * cipso_v4_doi_walk - Iterate through the DOI definitions
681  * @skip_cnt: skip past this number of DOI definitions, updated
682  * @callback: callback for each DOI definition
683  * @cb_arg: argument for the callback function
684  *
685  * Description:
686  * Iterate over the DOI definition list, skipping the first @skip_cnt entries.
687  * For each entry call @callback, if @callback returns a negative value stop
688  * 'walking' through the list and return.  Updates the value in @skip_cnt upon
689  * return.  Returns zero on success, negative values on failure.
690  *
691  */
692 int cipso_v4_doi_walk(u32 *skip_cnt,
693                      int (*callback) (struct cipso_v4_doi *doi_def, void *arg),
694                      void *cb_arg)
695 {
696         int ret_val = -ENOENT;
697         u32 doi_cnt = 0;
698         struct cipso_v4_doi *iter_doi;
699 
700         rcu_read_lock();
701         list_for_each_entry_rcu(iter_doi, &cipso_v4_doi_list, list)
702                 if (atomic_read(&iter_doi->refcount) > 0) {
703                         if (doi_cnt++ < *skip_cnt)
704                                 continue;
705                         ret_val = callback(iter_doi, cb_arg);
706                         if (ret_val < 0) {
707                                 doi_cnt--;
708                                 goto doi_walk_return;
709                         }
710                 }
711 
712 doi_walk_return:
713         rcu_read_unlock();
714         *skip_cnt = doi_cnt;
715         return ret_val;
716 }
717 
718 /*
719  * Label Mapping Functions
720  */
721 
722 /**
723  * cipso_v4_map_lvl_valid - Checks to see if the given level is understood
724  * @doi_def: the DOI definition
725  * @level: the level to check
726  *
727  * Description:
728  * Checks the given level against the given DOI definition and returns a
729  * negative value if the level does not have a valid mapping and a zero value
730  * if the level is defined by the DOI.
731  *
732  */
733 static int cipso_v4_map_lvl_valid(const struct cipso_v4_doi *doi_def, u8 level)
734 {
735         switch (doi_def->type) {
736         case CIPSO_V4_MAP_PASS:
737                 return 0;
738         case CIPSO_V4_MAP_TRANS:
739                 if ((level < doi_def->map.std->lvl.cipso_size) &&
740                     (doi_def->map.std->lvl.cipso[level] < CIPSO_V4_INV_LVL))
741                         return 0;
742                 break;
743         }
744 
745         return -EFAULT;
746 }
747 
748 /**
749  * cipso_v4_map_lvl_hton - Perform a level mapping from the host to the network
750  * @doi_def: the DOI definition
751  * @host_lvl: the host MLS level
752  * @net_lvl: the network/CIPSO MLS level
753  *
754  * Description:
755  * Perform a label mapping to translate a local MLS level to the correct
756  * CIPSO level using the given DOI definition.  Returns zero on success,
757  * negative values otherwise.
758  *
759  */
760 static int cipso_v4_map_lvl_hton(const struct cipso_v4_doi *doi_def,
761                                  u32 host_lvl,
762                                  u32 *net_lvl)
763 {
764         switch (doi_def->type) {
765         case CIPSO_V4_MAP_PASS:
766                 *net_lvl = host_lvl;
767                 return 0;
768         case CIPSO_V4_MAP_TRANS:
769                 if (host_lvl < doi_def->map.std->lvl.local_size &&
770                     doi_def->map.std->lvl.local[host_lvl] < CIPSO_V4_INV_LVL) {
771                         *net_lvl = doi_def->map.std->lvl.local[host_lvl];
772                         return 0;
773                 }
774                 return -EPERM;
775         }
776 
777         return -EINVAL;
778 }
779 
780 /**
781  * cipso_v4_map_lvl_ntoh - Perform a level mapping from the network to the host
782  * @doi_def: the DOI definition
783  * @net_lvl: the network/CIPSO MLS level
784  * @host_lvl: the host MLS level
785  *
786  * Description:
787  * Perform a label mapping to translate a CIPSO level to the correct local MLS
788  * level using the given DOI definition.  Returns zero on success, negative
789  * values otherwise.
790  *
791  */
792 static int cipso_v4_map_lvl_ntoh(const struct cipso_v4_doi *doi_def,
793                                  u32 net_lvl,
794                                  u32 *host_lvl)
795 {
796         struct cipso_v4_std_map_tbl *map_tbl;
797 
798         switch (doi_def->type) {
799         case CIPSO_V4_MAP_PASS:
800                 *host_lvl = net_lvl;
801                 return 0;
802         case CIPSO_V4_MAP_TRANS:
803                 map_tbl = doi_def->map.std;
804                 if (net_lvl < map_tbl->lvl.cipso_size &&
805                     map_tbl->lvl.cipso[net_lvl] < CIPSO_V4_INV_LVL) {
806                         *host_lvl = doi_def->map.std->lvl.cipso[net_lvl];
807                         return 0;
808                 }
809                 return -EPERM;
810         }
811 
812         return -EINVAL;
813 }
814 
815 /**
816  * cipso_v4_map_cat_rbm_valid - Checks to see if the category bitmap is valid
817  * @doi_def: the DOI definition
818  * @bitmap: category bitmap
819  * @bitmap_len: bitmap length in bytes
820  *
821  * Description:
822  * Checks the given category bitmap against the given DOI definition and
823  * returns a negative value if any of the categories in the bitmap do not have
824  * a valid mapping and a zero value if all of the categories are valid.
825  *
826  */
827 static int cipso_v4_map_cat_rbm_valid(const struct cipso_v4_doi *doi_def,
828                                       const unsigned char *bitmap,
829                                       u32 bitmap_len)
830 {
831         int cat = -1;
832         u32 bitmap_len_bits = bitmap_len * 8;
833         u32 cipso_cat_size;
834         u32 *cipso_array;
835 
836         switch (doi_def->type) {
837         case CIPSO_V4_MAP_PASS:
838                 return 0;
839         case CIPSO_V4_MAP_TRANS:
840                 cipso_cat_size = doi_def->map.std->cat.cipso_size;
841                 cipso_array = doi_def->map.std->cat.cipso;
842                 for (;;) {
843                         cat = cipso_v4_bitmap_walk(bitmap,
844                                                    bitmap_len_bits,
845                                                    cat + 1,
846                                                    1);
847                         if (cat < 0)
848                                 break;
849                         if (cat >= cipso_cat_size ||
850                             cipso_array[cat] >= CIPSO_V4_INV_CAT)
851                                 return -EFAULT;
852                 }
853 
854                 if (cat == -1)
855                         return 0;
856                 break;
857         }
858 
859         return -EFAULT;
860 }
861 
862 /**
863  * cipso_v4_map_cat_rbm_hton - Perform a category mapping from host to network
864  * @doi_def: the DOI definition
865  * @secattr: the security attributes
866  * @net_cat: the zero'd out category bitmap in network/CIPSO format
867  * @net_cat_len: the length of the CIPSO bitmap in bytes
868  *
869  * Description:
870  * Perform a label mapping to translate a local MLS category bitmap to the
871  * correct CIPSO bitmap using the given DOI definition.  Returns the minimum
872  * size in bytes of the network bitmap on success, negative values otherwise.
873  *
874  */
875 static int cipso_v4_map_cat_rbm_hton(const struct cipso_v4_doi *doi_def,
876                                      const struct netlbl_lsm_secattr *secattr,
877                                      unsigned char *net_cat,
878                                      u32 net_cat_len)
879 {
880         int host_spot = -1;
881         u32 net_spot = CIPSO_V4_INV_CAT;
882         u32 net_spot_max = 0;
883         u32 net_clen_bits = net_cat_len * 8;
884         u32 host_cat_size = 0;
885         u32 *host_cat_array = NULL;
886 
887         if (doi_def->type == CIPSO_V4_MAP_TRANS) {
888                 host_cat_size = doi_def->map.std->cat.local_size;
889                 host_cat_array = doi_def->map.std->cat.local;
890         }
891 
892         for (;;) {
893                 host_spot = netlbl_catmap_walk(secattr->attr.mls.cat,
894                                                host_spot + 1);
895                 if (host_spot < 0)
896                         break;
897 
898                 switch (doi_def->type) {
899                 case CIPSO_V4_MAP_PASS:
900                         net_spot = host_spot;
901                         break;
902                 case CIPSO_V4_MAP_TRANS:
903                         if (host_spot >= host_cat_size)
904                                 return -EPERM;
905                         net_spot = host_cat_array[host_spot];
906                         if (net_spot >= CIPSO_V4_INV_CAT)
907                                 return -EPERM;
908                         break;
909                 }
910                 if (net_spot >= net_clen_bits)
911                         return -ENOSPC;
912                 cipso_v4_bitmap_setbit(net_cat, net_spot, 1);
913 
914                 if (net_spot > net_spot_max)
915                         net_spot_max = net_spot;
916         }
917 
918         if (++net_spot_max % 8)
919                 return net_spot_max / 8 + 1;
920         return net_spot_max / 8;
921 }
922 
923 /**
924  * cipso_v4_map_cat_rbm_ntoh - Perform a category mapping from network to host
925  * @doi_def: the DOI definition
926  * @net_cat: the category bitmap in network/CIPSO format
927  * @net_cat_len: the length of the CIPSO bitmap in bytes
928  * @secattr: the security attributes
929  *
930  * Description:
931  * Perform a label mapping to translate a CIPSO bitmap to the correct local
932  * MLS category bitmap using the given DOI definition.  Returns zero on
933  * success, negative values on failure.
934  *
935  */
936 static int cipso_v4_map_cat_rbm_ntoh(const struct cipso_v4_doi *doi_def,
937                                      const unsigned char *net_cat,
938                                      u32 net_cat_len,
939                                      struct netlbl_lsm_secattr *secattr)
940 {
941         int ret_val;
942         int net_spot = -1;
943         u32 host_spot = CIPSO_V4_INV_CAT;
944         u32 net_clen_bits = net_cat_len * 8;
945         u32 net_cat_size = 0;
946         u32 *net_cat_array = NULL;
947 
948         if (doi_def->type == CIPSO_V4_MAP_TRANS) {
949                 net_cat_size = doi_def->map.std->cat.cipso_size;
950                 net_cat_array = doi_def->map.std->cat.cipso;
951         }
952 
953         for (;;) {
954                 net_spot = cipso_v4_bitmap_walk(net_cat,
955                                                 net_clen_bits,
956                                                 net_spot + 1,
957                                                 1);
958                 if (net_spot < 0) {
959                         if (net_spot == -2)
960                                 return -EFAULT;
961                         return 0;
962                 }
963 
964                 switch (doi_def->type) {
965                 case CIPSO_V4_MAP_PASS:
966                         host_spot = net_spot;
967                         break;
968                 case CIPSO_V4_MAP_TRANS:
969                         if (net_spot >= net_cat_size)
970                                 return -EPERM;
971                         host_spot = net_cat_array[net_spot];
972                         if (host_spot >= CIPSO_V4_INV_CAT)
973                                 return -EPERM;
974                         break;
975                 }
976                 ret_val = netlbl_catmap_setbit(&secattr->attr.mls.cat,
977                                                        host_spot,
978                                                        GFP_ATOMIC);
979                 if (ret_val != 0)
980                         return ret_val;
981         }
982 
983         return -EINVAL;
984 }
985 
986 /**
987  * cipso_v4_map_cat_enum_valid - Checks to see if the categories are valid
988  * @doi_def: the DOI definition
989  * @enumcat: category list
990  * @enumcat_len: length of the category list in bytes
991  *
992  * Description:
993  * Checks the given categories against the given DOI definition and returns a
994  * negative value if any of the categories do not have a valid mapping and a
995  * zero value if all of the categories are valid.
996  *
997  */
998 static int cipso_v4_map_cat_enum_valid(const struct cipso_v4_doi *doi_def,
999                                        const unsigned char *enumcat,
1000                                        u32 enumcat_len)
1001 {
1002         u16 cat;
1003         int cat_prev = -1;
1004         u32 iter;
1005 
1006         if (doi_def->type != CIPSO_V4_MAP_PASS || enumcat_len & 0x01)
1007                 return -EFAULT;
1008 
1009         for (iter = 0; iter < enumcat_len; iter += 2) {
1010                 cat = get_unaligned_be16(&enumcat[iter]);
1011                 if (cat <= cat_prev)
1012                         return -EFAULT;
1013                 cat_prev = cat;
1014         }
1015 
1016         return 0;
1017 }
1018 
1019 /**
1020  * cipso_v4_map_cat_enum_hton - Perform a category mapping from host to network
1021  * @doi_def: the DOI definition
1022  * @secattr: the security attributes
1023  * @net_cat: the zero'd out category list in network/CIPSO format
1024  * @net_cat_len: the length of the CIPSO category list in bytes
1025  *
1026  * Description:
1027  * Perform a label mapping to translate a local MLS category bitmap to the
1028  * correct CIPSO category list using the given DOI definition.   Returns the
1029  * size in bytes of the network category bitmap on success, negative values
1030  * otherwise.
1031  *
1032  */
1033 static int cipso_v4_map_cat_enum_hton(const struct cipso_v4_doi *doi_def,
1034                                       const struct netlbl_lsm_secattr *secattr,
1035                                       unsigned char *net_cat,
1036                                       u32 net_cat_len)
1037 {
1038         int cat = -1;
1039         u32 cat_iter = 0;
1040 
1041         for (;;) {
1042                 cat = netlbl_catmap_walk(secattr->attr.mls.cat, cat + 1);
1043                 if (cat < 0)
1044                         break;
1045                 if ((cat_iter + 2) > net_cat_len)
1046                         return -ENOSPC;
1047 
1048                 *((__be16 *)&net_cat[cat_iter]) = htons(cat);
1049                 cat_iter += 2;
1050         }
1051 
1052         return cat_iter;
1053 }
1054 
1055 /**
1056  * cipso_v4_map_cat_enum_ntoh - Perform a category mapping from network to host
1057  * @doi_def: the DOI definition
1058  * @net_cat: the category list in network/CIPSO format
1059  * @net_cat_len: the length of the CIPSO bitmap in bytes
1060  * @secattr: the security attributes
1061  *
1062  * Description:
1063  * Perform a label mapping to translate a CIPSO category list to the correct
1064  * local MLS category bitmap using the given DOI definition.  Returns zero on
1065  * success, negative values on failure.
1066  *
1067  */
1068 static int cipso_v4_map_cat_enum_ntoh(const struct cipso_v4_doi *doi_def,
1069                                       const unsigned char *net_cat,
1070                                       u32 net_cat_len,
1071                                       struct netlbl_lsm_secattr *secattr)
1072 {
1073         int ret_val;
1074         u32 iter;
1075 
1076         for (iter = 0; iter < net_cat_len; iter += 2) {
1077                 ret_val = netlbl_catmap_setbit(&secattr->attr.mls.cat,
1078                                              get_unaligned_be16(&net_cat[iter]),
1079                                              GFP_ATOMIC);
1080                 if (ret_val != 0)
1081                         return ret_val;
1082         }
1083 
1084         return 0;
1085 }
1086 
1087 /**
1088  * cipso_v4_map_cat_rng_valid - Checks to see if the categories are valid
1089  * @doi_def: the DOI definition
1090  * @rngcat: category list
1091  * @rngcat_len: length of the category list in bytes
1092  *
1093  * Description:
1094  * Checks the given categories against the given DOI definition and returns a
1095  * negative value if any of the categories do not have a valid mapping and a
1096  * zero value if all of the categories are valid.
1097  *
1098  */
1099 static int cipso_v4_map_cat_rng_valid(const struct cipso_v4_doi *doi_def,
1100                                       const unsigned char *rngcat,
1101                                       u32 rngcat_len)
1102 {
1103         u16 cat_high;
1104         u16 cat_low;
1105         u32 cat_prev = CIPSO_V4_MAX_REM_CATS + 1;
1106         u32 iter;
1107 
1108         if (doi_def->type != CIPSO_V4_MAP_PASS || rngcat_len & 0x01)
1109                 return -EFAULT;
1110 
1111         for (iter = 0; iter < rngcat_len; iter += 4) {
1112                 cat_high = get_unaligned_be16(&rngcat[iter]);
1113                 if ((iter + 4) <= rngcat_len)
1114                         cat_low = get_unaligned_be16(&rngcat[iter + 2]);
1115                 else
1116                         cat_low = 0;
1117 
1118                 if (cat_high > cat_prev)
1119                         return -EFAULT;
1120 
1121                 cat_prev = cat_low;
1122         }
1123 
1124         return 0;
1125 }
1126 
1127 /**
1128  * cipso_v4_map_cat_rng_hton - Perform a category mapping from host to network
1129  * @doi_def: the DOI definition
1130  * @secattr: the security attributes
1131  * @net_cat: the zero'd out category list in network/CIPSO format
1132  * @net_cat_len: the length of the CIPSO category list in bytes
1133  *
1134  * Description:
1135  * Perform a label mapping to translate a local MLS category bitmap to the
1136  * correct CIPSO category list using the given DOI definition.   Returns the
1137  * size in bytes of the network category bitmap on success, negative values
1138  * otherwise.
1139  *
1140  */
1141 static int cipso_v4_map_cat_rng_hton(const struct cipso_v4_doi *doi_def,
1142                                      const struct netlbl_lsm_secattr *secattr,
1143                                      unsigned char *net_cat,
1144                                      u32 net_cat_len)
1145 {
1146         int iter = -1;
1147         u16 array[CIPSO_V4_TAG_RNG_CAT_MAX * 2];
1148         u32 array_cnt = 0;
1149         u32 cat_size = 0;
1150 
1151         /* make sure we don't overflow the 'array[]' variable */
1152         if (net_cat_len >
1153             (CIPSO_V4_OPT_LEN_MAX - CIPSO_V4_HDR_LEN - CIPSO_V4_TAG_RNG_BLEN))
1154                 return -ENOSPC;
1155 
1156         for (;;) {
1157                 iter = netlbl_catmap_walk(secattr->attr.mls.cat, iter + 1);
1158                 if (iter < 0)
1159                         break;
1160                 cat_size += (iter == 0 ? 0 : sizeof(u16));
1161                 if (cat_size > net_cat_len)
1162                         return -ENOSPC;
1163                 array[array_cnt++] = iter;
1164 
1165                 iter = netlbl_catmap_walkrng(secattr->attr.mls.cat, iter);
1166                 if (iter < 0)
1167                         return -EFAULT;
1168                 cat_size += sizeof(u16);
1169                 if (cat_size > net_cat_len)
1170                         return -ENOSPC;
1171                 array[array_cnt++] = iter;
1172         }
1173 
1174         for (iter = 0; array_cnt > 0;) {
1175                 *((__be16 *)&net_cat[iter]) = htons(array[--array_cnt]);
1176                 iter += 2;
1177                 array_cnt--;
1178                 if (array[array_cnt] != 0) {
1179                         *((__be16 *)&net_cat[iter]) = htons(array[array_cnt]);
1180                         iter += 2;
1181                 }
1182         }
1183 
1184         return cat_size;
1185 }
1186 
1187 /**
1188  * cipso_v4_map_cat_rng_ntoh - Perform a category mapping from network to host
1189  * @doi_def: the DOI definition
1190  * @net_cat: the category list in network/CIPSO format
1191  * @net_cat_len: the length of the CIPSO bitmap in bytes
1192  * @secattr: the security attributes
1193  *
1194  * Description:
1195  * Perform a label mapping to translate a CIPSO category list to the correct
1196  * local MLS category bitmap using the given DOI definition.  Returns zero on
1197  * success, negative values on failure.
1198  *
1199  */
1200 static int cipso_v4_map_cat_rng_ntoh(const struct cipso_v4_doi *doi_def,
1201                                      const unsigned char *net_cat,
1202                                      u32 net_cat_len,
1203                                      struct netlbl_lsm_secattr *secattr)
1204 {
1205         int ret_val;
1206         u32 net_iter;
1207         u16 cat_low;
1208         u16 cat_high;
1209 
1210         for (net_iter = 0; net_iter < net_cat_len; net_iter += 4) {
1211                 cat_high = get_unaligned_be16(&net_cat[net_iter]);
1212                 if ((net_iter + 4) <= net_cat_len)
1213                         cat_low = get_unaligned_be16(&net_cat[net_iter + 2]);
1214                 else
1215                         cat_low = 0;
1216 
1217                 ret_val = netlbl_catmap_setrng(&secattr->attr.mls.cat,
1218                                                cat_low,
1219                                                cat_high,
1220                                                GFP_ATOMIC);
1221                 if (ret_val != 0)
1222                         return ret_val;
1223         }
1224 
1225         return 0;
1226 }
1227 
1228 /*
1229  * Protocol Handling Functions
1230  */
1231 
1232 /**
1233  * cipso_v4_gentag_hdr - Generate a CIPSO option header
1234  * @doi_def: the DOI definition
1235  * @len: the total tag length in bytes, not including this header
1236  * @buf: the CIPSO option buffer
1237  *
1238  * Description:
1239  * Write a CIPSO header into the beginning of @buffer.
1240  *
1241  */
1242 static void cipso_v4_gentag_hdr(const struct cipso_v4_doi *doi_def,
1243                                 unsigned char *buf,
1244                                 u32 len)
1245 {
1246         buf[0] = IPOPT_CIPSO;
1247         buf[1] = CIPSO_V4_HDR_LEN + len;
1248         *(__be32 *)&buf[2] = htonl(doi_def->doi);
1249 }
1250 
1251 /**
1252  * cipso_v4_gentag_rbm - Generate a CIPSO restricted bitmap tag (type #1)
1253  * @doi_def: the DOI definition
1254  * @secattr: the security attributes
1255  * @buffer: the option buffer
1256  * @buffer_len: length of buffer in bytes
1257  *
1258  * Description:
1259  * Generate a CIPSO option using the restricted bitmap tag, tag type #1.  The
1260  * actual buffer length may be larger than the indicated size due to
1261  * translation between host and network category bitmaps.  Returns the size of
1262  * the tag on success, negative values on failure.
1263  *
1264  */
1265 static int cipso_v4_gentag_rbm(const struct cipso_v4_doi *doi_def,
1266                                const struct netlbl_lsm_secattr *secattr,
1267                                unsigned char *buffer,
1268                                u32 buffer_len)
1269 {
1270         int ret_val;
1271         u32 tag_len;
1272         u32 level;
1273 
1274         if ((secattr->flags & NETLBL_SECATTR_MLS_LVL) == 0)
1275                 return -EPERM;
1276 
1277         ret_val = cipso_v4_map_lvl_hton(doi_def,
1278                                         secattr->attr.mls.lvl,
1279                                         &level);
1280         if (ret_val != 0)
1281                 return ret_val;
1282 
1283         if (secattr->flags & NETLBL_SECATTR_MLS_CAT) {
1284                 ret_val = cipso_v4_map_cat_rbm_hton(doi_def,
1285                                                     secattr,
1286                                                     &buffer[4],
1287                                                     buffer_len - 4);
1288                 if (ret_val < 0)
1289                         return ret_val;
1290 
1291                 /* This will send packets using the "optimized" format when
1292                  * possible as specified in  section 3.4.2.6 of the
1293                  * CIPSO draft. */
1294                 if (cipso_v4_rbm_optfmt && ret_val > 0 && ret_val <= 10)
1295                         tag_len = 14;
1296                 else
1297                         tag_len = 4 + ret_val;
1298         } else
1299                 tag_len = 4;
1300 
1301         buffer[0] = CIPSO_V4_TAG_RBITMAP;
1302         buffer[1] = tag_len;
1303         buffer[3] = level;
1304 
1305         return tag_len;
1306 }
1307 
1308 /**
1309  * cipso_v4_parsetag_rbm - Parse a CIPSO restricted bitmap tag
1310  * @doi_def: the DOI definition
1311  * @tag: the CIPSO tag
1312  * @secattr: the security attributes
1313  *
1314  * Description:
1315  * Parse a CIPSO restricted bitmap tag (tag type #1) and return the security
1316  * attributes in @secattr.  Return zero on success, negatives values on
1317  * failure.
1318  *
1319  */
1320 static int cipso_v4_parsetag_rbm(const struct cipso_v4_doi *doi_def,
1321                                  const unsigned char *tag,
1322                                  struct netlbl_lsm_secattr *secattr)
1323 {
1324         int ret_val;
1325         u8 tag_len = tag[1];
1326         u32 level;
1327 
1328         ret_val = cipso_v4_map_lvl_ntoh(doi_def, tag[3], &level);
1329         if (ret_val != 0)
1330                 return ret_val;
1331         secattr->attr.mls.lvl = level;
1332         secattr->flags |= NETLBL_SECATTR_MLS_LVL;
1333 
1334         if (tag_len > 4) {
1335                 ret_val = cipso_v4_map_cat_rbm_ntoh(doi_def,
1336                                                     &tag[4],
1337                                                     tag_len - 4,
1338                                                     secattr);
1339                 if (ret_val != 0) {
1340                         netlbl_catmap_free(secattr->attr.mls.cat);
1341                         return ret_val;
1342                 }
1343 
1344                 secattr->flags |= NETLBL_SECATTR_MLS_CAT;
1345         }
1346 
1347         return 0;
1348 }
1349 
1350 /**
1351  * cipso_v4_gentag_enum - Generate a CIPSO enumerated tag (type #2)
1352  * @doi_def: the DOI definition
1353  * @secattr: the security attributes
1354  * @buffer: the option buffer
1355  * @buffer_len: length of buffer in bytes
1356  *
1357  * Description:
1358  * Generate a CIPSO option using the enumerated tag, tag type #2.  Returns the
1359  * size of the tag on success, negative values on failure.
1360  *
1361  */
1362 static int cipso_v4_gentag_enum(const struct cipso_v4_doi *doi_def,
1363                                 const struct netlbl_lsm_secattr *secattr,
1364                                 unsigned char *buffer,
1365                                 u32 buffer_len)
1366 {
1367         int ret_val;
1368         u32 tag_len;
1369         u32 level;
1370 
1371         if (!(secattr->flags & NETLBL_SECATTR_MLS_LVL))
1372                 return -EPERM;
1373 
1374         ret_val = cipso_v4_map_lvl_hton(doi_def,
1375                                         secattr->attr.mls.lvl,
1376                                         &level);
1377         if (ret_val != 0)
1378                 return ret_val;
1379 
1380         if (secattr->flags & NETLBL_SECATTR_MLS_CAT) {
1381                 ret_val = cipso_v4_map_cat_enum_hton(doi_def,
1382                                                      secattr,
1383                                                      &buffer[4],
1384                                                      buffer_len - 4);
1385                 if (ret_val < 0)
1386                         return ret_val;
1387 
1388                 tag_len = 4 + ret_val;
1389         } else
1390                 tag_len = 4;
1391 
1392         buffer[0] = CIPSO_V4_TAG_ENUM;
1393         buffer[1] = tag_len;
1394         buffer[3] = level;
1395 
1396         return tag_len;
1397 }
1398 
1399 /**
1400  * cipso_v4_parsetag_enum - Parse a CIPSO enumerated tag
1401  * @doi_def: the DOI definition
1402  * @tag: the CIPSO tag
1403  * @secattr: the security attributes
1404  *
1405  * Description:
1406  * Parse a CIPSO enumerated tag (tag type #2) and return the security
1407  * attributes in @secattr.  Return zero on success, negatives values on
1408  * failure.
1409  *
1410  */
1411 static int cipso_v4_parsetag_enum(const struct cipso_v4_doi *doi_def,
1412                                   const unsigned char *tag,
1413                                   struct netlbl_lsm_secattr *secattr)
1414 {
1415         int ret_val;
1416         u8 tag_len = tag[1];
1417         u32 level;
1418 
1419         ret_val = cipso_v4_map_lvl_ntoh(doi_def, tag[3], &level);
1420         if (ret_val != 0)
1421                 return ret_val;
1422         secattr->attr.mls.lvl = level;
1423         secattr->flags |= NETLBL_SECATTR_MLS_LVL;
1424 
1425         if (tag_len > 4) {
1426                 ret_val = cipso_v4_map_cat_enum_ntoh(doi_def,
1427                                                      &tag[4],
1428                                                      tag_len - 4,
1429                                                      secattr);
1430                 if (ret_val != 0) {
1431                         netlbl_catmap_free(secattr->attr.mls.cat);
1432                         return ret_val;
1433                 }
1434 
1435                 secattr->flags |= NETLBL_SECATTR_MLS_CAT;
1436         }
1437 
1438         return 0;
1439 }
1440 
1441 /**
1442  * cipso_v4_gentag_rng - Generate a CIPSO ranged tag (type #5)
1443  * @doi_def: the DOI definition
1444  * @secattr: the security attributes
1445  * @buffer: the option buffer
1446  * @buffer_len: length of buffer in bytes
1447  *
1448  * Description:
1449  * Generate a CIPSO option using the ranged tag, tag type #5.  Returns the
1450  * size of the tag on success, negative values on failure.
1451  *
1452  */
1453 static int cipso_v4_gentag_rng(const struct cipso_v4_doi *doi_def,
1454                                const struct netlbl_lsm_secattr *secattr,
1455                                unsigned char *buffer,
1456                                u32 buffer_len)
1457 {
1458         int ret_val;
1459         u32 tag_len;
1460         u32 level;
1461 
1462         if (!(secattr->flags & NETLBL_SECATTR_MLS_LVL))
1463                 return -EPERM;
1464 
1465         ret_val = cipso_v4_map_lvl_hton(doi_def,
1466                                         secattr->attr.mls.lvl,
1467                                         &level);
1468         if (ret_val != 0)
1469                 return ret_val;
1470 
1471         if (secattr->flags & NETLBL_SECATTR_MLS_CAT) {
1472                 ret_val = cipso_v4_map_cat_rng_hton(doi_def,
1473                                                     secattr,
1474                                                     &buffer[4],
1475                                                     buffer_len - 4);
1476                 if (ret_val < 0)
1477                         return ret_val;
1478 
1479                 tag_len = 4 + ret_val;
1480         } else
1481                 tag_len = 4;
1482 
1483         buffer[0] = CIPSO_V4_TAG_RANGE;
1484         buffer[1] = tag_len;
1485         buffer[3] = level;
1486 
1487         return tag_len;
1488 }
1489 
1490 /**
1491  * cipso_v4_parsetag_rng - Parse a CIPSO ranged tag
1492  * @doi_def: the DOI definition
1493  * @tag: the CIPSO tag
1494  * @secattr: the security attributes
1495  *
1496  * Description:
1497  * Parse a CIPSO ranged tag (tag type #5) and return the security attributes
1498  * in @secattr.  Return zero on success, negatives values on failure.
1499  *
1500  */
1501 static int cipso_v4_parsetag_rng(const struct cipso_v4_doi *doi_def,
1502                                  const unsigned char *tag,
1503                                  struct netlbl_lsm_secattr *secattr)
1504 {
1505         int ret_val;
1506         u8 tag_len = tag[1];
1507         u32 level;
1508 
1509         ret_val = cipso_v4_map_lvl_ntoh(doi_def, tag[3], &level);
1510         if (ret_val != 0)
1511                 return ret_val;
1512         secattr->attr.mls.lvl = level;
1513         secattr->flags |= NETLBL_SECATTR_MLS_LVL;
1514 
1515         if (tag_len > 4) {
1516                 ret_val = cipso_v4_map_cat_rng_ntoh(doi_def,
1517                                                     &tag[4],
1518                                                     tag_len - 4,
1519                                                     secattr);
1520                 if (ret_val != 0) {
1521                         netlbl_catmap_free(secattr->attr.mls.cat);
1522                         return ret_val;
1523                 }
1524 
1525                 secattr->flags |= NETLBL_SECATTR_MLS_CAT;
1526         }
1527 
1528         return 0;
1529 }
1530 
1531 /**
1532  * cipso_v4_gentag_loc - Generate a CIPSO local tag (non-standard)
1533  * @doi_def: the DOI definition
1534  * @secattr: the security attributes
1535  * @buffer: the option buffer
1536  * @buffer_len: length of buffer in bytes
1537  *
1538  * Description:
1539  * Generate a CIPSO option using the local tag.  Returns the size of the tag
1540  * on success, negative values on failure.
1541  *
1542  */
1543 static int cipso_v4_gentag_loc(const struct cipso_v4_doi *doi_def,
1544                                const struct netlbl_lsm_secattr *secattr,
1545                                unsigned char *buffer,
1546                                u32 buffer_len)
1547 {
1548         if (!(secattr->flags & NETLBL_SECATTR_SECID))
1549                 return -EPERM;
1550 
1551         buffer[0] = CIPSO_V4_TAG_LOCAL;
1552         buffer[1] = CIPSO_V4_TAG_LOC_BLEN;
1553         *(u32 *)&buffer[2] = secattr->attr.secid;
1554 
1555         return CIPSO_V4_TAG_LOC_BLEN;
1556 }
1557 
1558 /**
1559  * cipso_v4_parsetag_loc - Parse a CIPSO local tag
1560  * @doi_def: the DOI definition
1561  * @tag: the CIPSO tag
1562  * @secattr: the security attributes
1563  *
1564  * Description:
1565  * Parse a CIPSO local tag and return the security attributes in @secattr.
1566  * Return zero on success, negatives values on failure.
1567  *
1568  */
1569 static int cipso_v4_parsetag_loc(const struct cipso_v4_doi *doi_def,
1570                                  const unsigned char *tag,
1571                                  struct netlbl_lsm_secattr *secattr)
1572 {
1573         secattr->attr.secid = *(u32 *)&tag[2];
1574         secattr->flags |= NETLBL_SECATTR_SECID;
1575 
1576         return 0;
1577 }
1578 
1579 /**
1580  * cipso_v4_optptr - Find the CIPSO option in the packet
1581  * @skb: the packet
1582  *
1583  * Description:
1584  * Parse the packet's IP header looking for a CIPSO option.  Returns a pointer
1585  * to the start of the CIPSO option on success, NULL if one is not found.
1586  *
1587  */
1588 unsigned char *cipso_v4_optptr(const struct sk_buff *skb)
1589 {
1590         const struct iphdr *iph = ip_hdr(skb);
1591         unsigned char *optptr = (unsigned char *)&(ip_hdr(skb)[1]);
1592         int optlen;
1593         int taglen;
1594 
1595         for (optlen = iph->ihl*4 - sizeof(struct iphdr); optlen > 1; ) {
1596                 switch (optptr[0]) {
1597                 case IPOPT_END:
1598                         return NULL;
1599                 case IPOPT_NOOP:
1600                         taglen = 1;
1601                         break;
1602                 default:
1603                         taglen = optptr[1];
1604                 }
1605                 if (!taglen || taglen > optlen)
1606                         return NULL;
1607                 if (optptr[0] == IPOPT_CIPSO)
1608                         return optptr;
1609 
1610                 optlen -= taglen;
1611                 optptr += taglen;
1612         }
1613 
1614         return NULL;
1615 }
1616 
1617 /**
1618  * cipso_v4_validate - Validate a CIPSO option
1619  * @option: the start of the option, on error it is set to point to the error
1620  *
1621  * Description:
1622  * This routine is called to validate a CIPSO option, it checks all of the
1623  * fields to ensure that they are at least valid, see the draft snippet below
1624  * for details.  If the option is valid then a zero value is returned and
1625  * the value of @option is unchanged.  If the option is invalid then a
1626  * non-zero value is returned and @option is adjusted to point to the
1627  * offending portion of the option.  From the IETF draft ...
1628  *
1629  *  "If any field within the CIPSO options, such as the DOI identifier, is not
1630  *   recognized the IP datagram is discarded and an ICMP 'parameter problem'
1631  *   (type 12) is generated and returned.  The ICMP code field is set to 'bad
1632  *   parameter' (code 0) and the pointer is set to the start of the CIPSO field
1633  *   that is unrecognized."
1634  *
1635  */
1636 int cipso_v4_validate(const struct sk_buff *skb, unsigned char **option)
1637 {
1638         unsigned char *opt = *option;
1639         unsigned char *tag;
1640         unsigned char opt_iter;
1641         unsigned char err_offset = 0;
1642         u8 opt_len;
1643         u8 tag_len;
1644         struct cipso_v4_doi *doi_def = NULL;
1645         u32 tag_iter;
1646 
1647         /* caller already checks for length values that are too large */
1648         opt_len = opt[1];
1649         if (opt_len < 8) {
1650                 err_offset = 1;
1651                 goto validate_return;
1652         }
1653 
1654         rcu_read_lock();
1655         doi_def = cipso_v4_doi_search(get_unaligned_be32(&opt[2]));
1656         if (doi_def == NULL) {
1657                 err_offset = 2;
1658                 goto validate_return_locked;
1659         }
1660 
1661         opt_iter = CIPSO_V4_HDR_LEN;
1662         tag = opt + opt_iter;
1663         while (opt_iter < opt_len) {
1664                 for (tag_iter = 0; doi_def->tags[tag_iter] != tag[0];)
1665                         if (doi_def->tags[tag_iter] == CIPSO_V4_TAG_INVALID ||
1666                             ++tag_iter == CIPSO_V4_TAG_MAXCNT) {
1667                                 err_offset = opt_iter;
1668                                 goto validate_return_locked;
1669                         }
1670 
1671                 if (opt_iter + 1 == opt_len) {
1672                         err_offset = opt_iter;
1673                         goto validate_return_locked;
1674                 }
1675                 tag_len = tag[1];
1676                 if (tag_len > (opt_len - opt_iter)) {
1677                         err_offset = opt_iter + 1;
1678                         goto validate_return_locked;
1679                 }
1680 
1681                 switch (tag[0]) {
1682                 case CIPSO_V4_TAG_RBITMAP:
1683                         if (tag_len < CIPSO_V4_TAG_RBM_BLEN) {
1684                                 err_offset = opt_iter + 1;
1685                                 goto validate_return_locked;
1686                         }
1687 
1688                         /* We are already going to do all the verification
1689                          * necessary at the socket layer so from our point of
1690                          * view it is safe to turn these checks off (and less
1691                          * work), however, the CIPSO draft says we should do
1692                          * all the CIPSO validations here but it doesn't
1693                          * really specify _exactly_ what we need to validate
1694                          * ... so, just make it a sysctl tunable. */
1695                         if (cipso_v4_rbm_strictvalid) {
1696                                 if (cipso_v4_map_lvl_valid(doi_def,
1697                                                            tag[3]) < 0) {
1698                                         err_offset = opt_iter + 3;
1699                                         goto validate_return_locked;
1700                                 }
1701                                 if (tag_len > CIPSO_V4_TAG_RBM_BLEN &&
1702                                     cipso_v4_map_cat_rbm_valid(doi_def,
1703                                                             &tag[4],
1704                                                             tag_len - 4) < 0) {
1705                                         err_offset = opt_iter + 4;
1706                                         goto validate_return_locked;
1707                                 }
1708                         }
1709                         break;
1710                 case CIPSO_V4_TAG_ENUM:
1711                         if (tag_len < CIPSO_V4_TAG_ENUM_BLEN) {
1712                                 err_offset = opt_iter + 1;
1713                                 goto validate_return_locked;
1714                         }
1715 
1716                         if (cipso_v4_map_lvl_valid(doi_def,
1717                                                    tag[3]) < 0) {
1718                                 err_offset = opt_iter + 3;
1719                                 goto validate_return_locked;
1720                         }
1721                         if (tag_len > CIPSO_V4_TAG_ENUM_BLEN &&
1722                             cipso_v4_map_cat_enum_valid(doi_def,
1723                                                         &tag[4],
1724                                                         tag_len - 4) < 0) {
1725                                 err_offset = opt_iter + 4;
1726                                 goto validate_return_locked;
1727                         }
1728                         break;
1729                 case CIPSO_V4_TAG_RANGE:
1730                         if (tag_len < CIPSO_V4_TAG_RNG_BLEN) {
1731                                 err_offset = opt_iter + 1;
1732                                 goto validate_return_locked;
1733                         }
1734 
1735                         if (cipso_v4_map_lvl_valid(doi_def,
1736                                                    tag[3]) < 0) {
1737                                 err_offset = opt_iter + 3;
1738                                 goto validate_return_locked;
1739                         }
1740                         if (tag_len > CIPSO_V4_TAG_RNG_BLEN &&
1741                             cipso_v4_map_cat_rng_valid(doi_def,
1742                                                        &tag[4],
1743                                                        tag_len - 4) < 0) {
1744                                 err_offset = opt_iter + 4;
1745                                 goto validate_return_locked;
1746                         }
1747                         break;
1748                 case CIPSO_V4_TAG_LOCAL:
1749                         /* This is a non-standard tag that we only allow for
1750                          * local connections, so if the incoming interface is
1751                          * not the loopback device drop the packet. Further,
1752                          * there is no legitimate reason for setting this from
1753                          * userspace so reject it if skb is NULL. */
1754                         if (skb == NULL || !(skb->dev->flags & IFF_LOOPBACK)) {
1755                                 err_offset = opt_iter;
1756                                 goto validate_return_locked;
1757                         }
1758                         if (tag_len != CIPSO_V4_TAG_LOC_BLEN) {
1759                                 err_offset = opt_iter + 1;
1760                                 goto validate_return_locked;
1761                         }
1762                         break;
1763                 default:
1764                         err_offset = opt_iter;
1765                         goto validate_return_locked;
1766                 }
1767 
1768                 tag += tag_len;
1769                 opt_iter += tag_len;
1770         }
1771 
1772 validate_return_locked:
1773         rcu_read_unlock();
1774 validate_return:
1775         *option = opt + err_offset;
1776         return err_offset;
1777 }
1778 
1779 /**
1780  * cipso_v4_error - Send the correct response for a bad packet
1781  * @skb: the packet
1782  * @error: the error code
1783  * @gateway: CIPSO gateway flag
1784  *
1785  * Description:
1786  * Based on the error code given in @error, send an ICMP error message back to
1787  * the originating host.  From the IETF draft ...
1788  *
1789  *  "If the contents of the CIPSO [option] are valid but the security label is
1790  *   outside of the configured host or port label range, the datagram is
1791  *   discarded and an ICMP 'destination unreachable' (type 3) is generated and
1792  *   returned.  The code field of the ICMP is set to 'communication with
1793  *   destination network administratively prohibited' (code 9) or to
1794  *   'communication with destination host administratively prohibited'
1795  *   (code 10).  The value of the code is dependent on whether the originator
1796  *   of the ICMP message is acting as a CIPSO host or a CIPSO gateway.  The
1797  *   recipient of the ICMP message MUST be able to handle either value.  The
1798  *   same procedure is performed if a CIPSO [option] can not be added to an
1799  *   IP packet because it is too large to fit in the IP options area."
1800  *
1801  *  "If the error is triggered by receipt of an ICMP message, the message is
1802  *   discarded and no response is permitted (consistent with general ICMP
1803  *   processing rules)."
1804  *
1805  */
1806 void cipso_v4_error(struct sk_buff *skb, int error, u32 gateway)
1807 {
1808         unsigned char optbuf[sizeof(struct ip_options) + 40];
1809         struct ip_options *opt = (struct ip_options *)optbuf;
1810 
1811         if (ip_hdr(skb)->protocol == IPPROTO_ICMP || error != -EACCES)
1812                 return;
1813 
1814         /*
1815          * We might be called above the IP layer,
1816          * so we can not use icmp_send and IPCB here.
1817          */
1818 
1819         memset(opt, 0, sizeof(struct ip_options));
1820         opt->optlen = ip_hdr(skb)->ihl*4 - sizeof(struct iphdr);
1821         if (__ip_options_compile(dev_net(skb->dev), opt, skb, NULL))
1822                 return;
1823 
1824         if (gateway)
1825                 __icmp_send(skb, ICMP_DEST_UNREACH, ICMP_NET_ANO, 0, opt);
1826         else
1827                 __icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_ANO, 0, opt);
1828 }
1829 
1830 /**
1831  * cipso_v4_genopt - Generate a CIPSO option
1832  * @buf: the option buffer
1833  * @buf_len: the size of opt_buf
1834  * @doi_def: the CIPSO DOI to use
1835  * @secattr: the security attributes
1836  *
1837  * Description:
1838  * Generate a CIPSO option using the DOI definition and security attributes
1839  * passed to the function.  Returns the length of the option on success and
1840  * negative values on failure.
1841  *
1842  */
1843 static int cipso_v4_genopt(unsigned char *buf, u32 buf_len,
1844                            const struct cipso_v4_doi *doi_def,
1845                            const struct netlbl_lsm_secattr *secattr)
1846 {
1847         int ret_val;
1848         u32 iter;
1849 
1850         if (buf_len <= CIPSO_V4_HDR_LEN)
1851                 return -ENOSPC;
1852 
1853         /* XXX - This code assumes only one tag per CIPSO option which isn't
1854          * really a good assumption to make but since we only support the MAC
1855          * tags right now it is a safe assumption. */
1856         iter = 0;
1857         do {
1858                 memset(buf, 0, buf_len);
1859                 switch (doi_def->tags[iter]) {
1860                 case CIPSO_V4_TAG_RBITMAP:
1861                         ret_val = cipso_v4_gentag_rbm(doi_def,
1862                                                    secattr,
1863                                                    &buf[CIPSO_V4_HDR_LEN],
1864                                                    buf_len - CIPSO_V4_HDR_LEN);
1865                         break;
1866                 case CIPSO_V4_TAG_ENUM:
1867                         ret_val = cipso_v4_gentag_enum(doi_def,
1868                                                    secattr,
1869                                                    &buf[CIPSO_V4_HDR_LEN],
1870                                                    buf_len - CIPSO_V4_HDR_LEN);
1871                         break;
1872                 case CIPSO_V4_TAG_RANGE:
1873                         ret_val = cipso_v4_gentag_rng(doi_def,
1874                                                    secattr,
1875                                                    &buf[CIPSO_V4_HDR_LEN],
1876                                                    buf_len - CIPSO_V4_HDR_LEN);
1877                         break;
1878                 case CIPSO_V4_TAG_LOCAL:
1879                         ret_val = cipso_v4_gentag_loc(doi_def,
1880                                                    secattr,
1881                                                    &buf[CIPSO_V4_HDR_LEN],
1882                                                    buf_len - CIPSO_V4_HDR_LEN);
1883                         break;
1884                 default:
1885                         return -EPERM;
1886                 }
1887 
1888                 iter++;
1889         } while (ret_val < 0 &&
1890                  iter < CIPSO_V4_TAG_MAXCNT &&
1891                  doi_def->tags[iter] != CIPSO_V4_TAG_INVALID);
1892         if (ret_val < 0)
1893                 return ret_val;
1894         cipso_v4_gentag_hdr(doi_def, buf, ret_val);
1895         return CIPSO_V4_HDR_LEN + ret_val;
1896 }
1897 
1898 /**
1899  * cipso_v4_sock_setattr - Add a CIPSO option to a socket
1900  * @sk: the socket
1901  * @doi_def: the CIPSO DOI to use
1902  * @secattr: the specific security attributes of the socket
1903  *
1904  * Description:
1905  * Set the CIPSO option on the given socket using the DOI definition and
1906  * security attributes passed to the function.  This function requires
1907  * exclusive access to @sk, which means it either needs to be in the
1908  * process of being created or locked.  Returns zero on success and negative
1909  * values on failure.
1910  *
1911  */
1912 int cipso_v4_sock_setattr(struct sock *sk,
1913                           const struct cipso_v4_doi *doi_def,
1914                           const struct netlbl_lsm_secattr *secattr)
1915 {
1916         int ret_val = -EPERM;
1917         unsigned char *buf = NULL;
1918         u32 buf_len;
1919         u32 opt_len;
1920         struct ip_options_rcu *old, *opt = NULL;
1921         struct inet_sock *sk_inet;
1922         struct inet_connection_sock *sk_conn;
1923 
1924         /* In the case of sock_create_lite(), the sock->sk field is not
1925          * defined yet but it is not a problem as the only users of these
1926          * "lite" PF_INET sockets are functions which do an accept() call
1927          * afterwards so we will label the socket as part of the accept(). */
1928         if (sk == NULL)
1929                 return 0;
1930 
1931         /* We allocate the maximum CIPSO option size here so we are probably
1932          * being a little wasteful, but it makes our life _much_ easier later
1933          * on and after all we are only talking about 40 bytes. */
1934         buf_len = CIPSO_V4_OPT_LEN_MAX;
1935         buf = kmalloc(buf_len, GFP_ATOMIC);
1936         if (buf == NULL) {
1937                 ret_val = -ENOMEM;
1938                 goto socket_setattr_failure;
1939         }
1940 
1941         ret_val = cipso_v4_genopt(buf, buf_len, doi_def, secattr);
1942         if (ret_val < 0)
1943                 goto socket_setattr_failure;
1944         buf_len = ret_val;
1945 
1946         /* We can't use ip_options_get() directly because it makes a call to
1947          * ip_options_get_alloc() which allocates memory with GFP_KERNEL and
1948          * we won't always have CAP_NET_RAW even though we _always_ want to
1949          * set the IPOPT_CIPSO option. */
1950         opt_len = (buf_len + 3) & ~3;
1951         opt = kzalloc(sizeof(*opt) + opt_len, GFP_ATOMIC);
1952         if (opt == NULL) {
1953                 ret_val = -ENOMEM;
1954                 goto socket_setattr_failure;
1955         }
1956         memcpy(opt->opt.__data, buf, buf_len);
1957         opt->opt.optlen = opt_len;
1958         opt->opt.cipso = sizeof(struct iphdr);
1959         kfree(buf);
1960         buf = NULL;
1961 
1962         sk_inet = inet_sk(sk);
1963 
1964         old = rcu_dereference_protected(sk_inet->inet_opt, sock_owned_by_user(sk));
1965         if (sk_inet->is_icsk) {
1966                 sk_conn = inet_csk(sk);
1967                 if (old)
1968                         sk_conn->icsk_ext_hdr_len -= old->opt.optlen;
1969                 sk_conn->icsk_ext_hdr_len += opt->opt.optlen;
1970                 sk_conn->icsk_sync_mss(sk, sk_conn->icsk_pmtu_cookie);
1971         }
1972         rcu_assign_pointer(sk_inet->inet_opt, opt);
1973         if (old)
1974                 kfree_rcu(old, rcu);
1975 
1976         return 0;
1977 
1978 socket_setattr_failure:
1979         kfree(buf);
1980         kfree(opt);
1981         return ret_val;
1982 }
1983 
1984 /**
1985  * cipso_v4_req_setattr - Add a CIPSO option to a connection request socket
1986  * @req: the connection request socket
1987  * @doi_def: the CIPSO DOI to use
1988  * @secattr: the specific security attributes of the socket
1989  *
1990  * Description:
1991  * Set the CIPSO option on the given socket using the DOI definition and
1992  * security attributes passed to the function.  Returns zero on success and
1993  * negative values on failure.
1994  *
1995  */
1996 int cipso_v4_req_setattr(struct request_sock *req,
1997                          const struct cipso_v4_doi *doi_def,
1998                          const struct netlbl_lsm_secattr *secattr)
1999 {
2000         int ret_val = -EPERM;
2001         unsigned char *buf = NULL;
2002         u32 buf_len;
2003         u32 opt_len;
2004         struct ip_options_rcu *opt = NULL;
2005         struct inet_request_sock *req_inet;
2006 
2007         /* We allocate the maximum CIPSO option size here so we are probably
2008          * being a little wasteful, but it makes our life _much_ easier later
2009          * on and after all we are only talking about 40 bytes. */
2010         buf_len = CIPSO_V4_OPT_LEN_MAX;
2011         buf = kmalloc(buf_len, GFP_ATOMIC);
2012         if (buf == NULL) {
2013                 ret_val = -ENOMEM;
2014                 goto req_setattr_failure;
2015         }
2016 
2017         ret_val = cipso_v4_genopt(buf, buf_len, doi_def, secattr);
2018         if (ret_val < 0)
2019                 goto req_setattr_failure;
2020         buf_len = ret_val;
2021 
2022         /* We can't use ip_options_get() directly because it makes a call to
2023          * ip_options_get_alloc() which allocates memory with GFP_KERNEL and
2024          * we won't always have CAP_NET_RAW even though we _always_ want to
2025          * set the IPOPT_CIPSO option. */
2026         opt_len = (buf_len + 3) & ~3;
2027         opt = kzalloc(sizeof(*opt) + opt_len, GFP_ATOMIC);
2028         if (opt == NULL) {
2029                 ret_val = -ENOMEM;
2030                 goto req_setattr_failure;
2031         }
2032         memcpy(opt->opt.__data, buf, buf_len);
2033         opt->opt.optlen = opt_len;
2034         opt->opt.cipso = sizeof(struct iphdr);
2035         kfree(buf);
2036         buf = NULL;
2037 
2038         req_inet = inet_rsk(req);
2039         opt = xchg(&req_inet->opt, opt);
2040         if (opt)
2041                 kfree_rcu(opt, rcu);
2042 
2043         return 0;
2044 
2045 req_setattr_failure:
2046         kfree(buf);
2047         kfree(opt);
2048         return ret_val;
2049 }
2050 
2051 /**
2052  * cipso_v4_delopt - Delete the CIPSO option from a set of IP options
2053  * @opt_ptr: IP option pointer
2054  *
2055  * Description:
2056  * Deletes the CIPSO IP option from a set of IP options and makes the necessary
2057  * adjustments to the IP option structure.  Returns zero on success, negative
2058  * values on failure.
2059  *
2060  */
2061 static int cipso_v4_delopt(struct ip_options_rcu **opt_ptr)
2062 {
2063         int hdr_delta = 0;
2064         struct ip_options_rcu *opt = *opt_ptr;
2065 
2066         if (opt->opt.srr || opt->opt.rr || opt->opt.ts || opt->opt.router_alert) {
2067                 u8 cipso_len;
2068                 u8 cipso_off;
2069                 unsigned char *cipso_ptr;
2070                 int iter;
2071                 int optlen_new;
2072 
2073                 cipso_off = opt->opt.cipso - sizeof(struct iphdr);
2074                 cipso_ptr = &opt->opt.__data[cipso_off];
2075                 cipso_len = cipso_ptr[1];
2076 
2077                 if (opt->opt.srr > opt->opt.cipso)
2078                         opt->opt.srr -= cipso_len;
2079                 if (opt->opt.rr > opt->opt.cipso)
2080                         opt->opt.rr -= cipso_len;
2081                 if (opt->opt.ts > opt->opt.cipso)
2082                         opt->opt.ts -= cipso_len;
2083                 if (opt->opt.router_alert > opt->opt.cipso)
2084                         opt->opt.router_alert -= cipso_len;
2085                 opt->opt.cipso = 0;
2086 
2087                 memmove(cipso_ptr, cipso_ptr + cipso_len,
2088                         opt->opt.optlen - cipso_off - cipso_len);
2089 
2090                 /* determining the new total option length is tricky because of
2091                  * the padding necessary, the only thing i can think to do at
2092                  * this point is walk the options one-by-one, skipping the
2093                  * padding at the end to determine the actual option size and
2094                  * from there we can determine the new total option length */
2095                 iter = 0;
2096                 optlen_new = 0;
2097                 while (iter < opt->opt.optlen)
2098                         if (opt->opt.__data[iter] != IPOPT_NOP) {
2099                                 iter += opt->opt.__data[iter + 1];
2100                                 optlen_new = iter;
2101                         } else
2102                                 iter++;
2103                 hdr_delta = opt->opt.optlen;
2104                 opt->opt.optlen = (optlen_new + 3) & ~3;
2105                 hdr_delta -= opt->opt.optlen;
2106         } else {
2107                 /* only the cipso option was present on the socket so we can
2108                  * remove the entire option struct */
2109                 *opt_ptr = NULL;
2110                 hdr_delta = opt->opt.optlen;
2111                 kfree_rcu(opt, rcu);
2112         }
2113 
2114         return hdr_delta;
2115 }
2116 
2117 /**
2118  * cipso_v4_sock_delattr - Delete the CIPSO option from a socket
2119  * @sk: the socket
2120  *
2121  * Description:
2122  * Removes the CIPSO option from a socket, if present.
2123  *
2124  */
2125 void cipso_v4_sock_delattr(struct sock *sk)
2126 {
2127         int hdr_delta;
2128         struct ip_options_rcu *opt;
2129         struct inet_sock *sk_inet;
2130 
2131         sk_inet = inet_sk(sk);
2132         opt = rcu_dereference_protected(sk_inet->inet_opt, 1);
2133         if (opt == NULL || opt->opt.cipso == 0)
2134                 return;
2135 
2136         hdr_delta = cipso_v4_delopt(&sk_inet->inet_opt);
2137         if (sk_inet->is_icsk && hdr_delta > 0) {
2138                 struct inet_connection_sock *sk_conn = inet_csk(sk);
2139                 sk_conn->icsk_ext_hdr_len -= hdr_delta;
2140                 sk_conn->icsk_sync_mss(sk, sk_conn->icsk_pmtu_cookie);
2141         }
2142 }
2143 
2144 /**
2145  * cipso_v4_req_delattr - Delete the CIPSO option from a request socket
2146  * @reg: the request socket
2147  *
2148  * Description:
2149  * Removes the CIPSO option from a request socket, if present.
2150  *
2151  */
2152 void cipso_v4_req_delattr(struct request_sock *req)
2153 {
2154         struct ip_options_rcu *opt;
2155         struct inet_request_sock *req_inet;
2156 
2157         req_inet = inet_rsk(req);
2158         opt = req_inet->opt;
2159         if (opt == NULL || opt->opt.cipso == 0)
2160                 return;
2161 
2162         cipso_v4_delopt(&req_inet->opt);
2163 }
2164 
2165 /**
2166  * cipso_v4_getattr - Helper function for the cipso_v4_*_getattr functions
2167  * @cipso: the CIPSO v4 option
2168  * @secattr: the security attributes
2169  *
2170  * Description:
2171  * Inspect @cipso and return the security attributes in @secattr.  Returns zero
2172  * on success and negative values on failure.
2173  *
2174  */
2175 int cipso_v4_getattr(const unsigned char *cipso,
2176                      struct netlbl_lsm_secattr *secattr)
2177 {
2178         int ret_val = -ENOMSG;
2179         u32 doi;
2180         struct cipso_v4_doi *doi_def;
2181 
2182         if (cipso_v4_cache_check(cipso, cipso[1], secattr) == 0)
2183                 return 0;
2184 
2185         doi = get_unaligned_be32(&cipso[2]);
2186         rcu_read_lock();
2187         doi_def = cipso_v4_doi_search(doi);
2188         if (doi_def == NULL)
2189                 goto getattr_return;
2190         /* XXX - This code assumes only one tag per CIPSO option which isn't
2191          * really a good assumption to make but since we only support the MAC
2192          * tags right now it is a safe assumption. */
2193         switch (cipso[6]) {
2194         case CIPSO_V4_TAG_RBITMAP:
2195                 ret_val = cipso_v4_parsetag_rbm(doi_def, &cipso[6], secattr);
2196                 break;
2197         case CIPSO_V4_TAG_ENUM:
2198                 ret_val = cipso_v4_parsetag_enum(doi_def, &cipso[6], secattr);
2199                 break;
2200         case CIPSO_V4_TAG_RANGE:
2201                 ret_val = cipso_v4_parsetag_rng(doi_def, &cipso[6], secattr);
2202                 break;
2203         case CIPSO_V4_TAG_LOCAL:
2204                 ret_val = cipso_v4_parsetag_loc(doi_def, &cipso[6], secattr);
2205                 break;
2206         }
2207         if (ret_val == 0)
2208                 secattr->type = NETLBL_NLTYPE_CIPSOV4;
2209 
2210 getattr_return:
2211         rcu_read_unlock();
2212         return ret_val;
2213 }
2214 
2215 /**
2216  * cipso_v4_sock_getattr - Get the security attributes from a sock
2217  * @sk: the sock
2218  * @secattr: the security attributes
2219  *
2220  * Description:
2221  * Query @sk to see if there is a CIPSO option attached to the sock and if
2222  * there is return the CIPSO security attributes in @secattr.  This function
2223  * requires that @sk be locked, or privately held, but it does not do any
2224  * locking itself.  Returns zero on success and negative values on failure.
2225  *
2226  */
2227 int cipso_v4_sock_getattr(struct sock *sk, struct netlbl_lsm_secattr *secattr)
2228 {
2229         struct ip_options_rcu *opt;
2230         int res = -ENOMSG;
2231 
2232         rcu_read_lock();
2233         opt = rcu_dereference(inet_sk(sk)->inet_opt);
2234         if (opt && opt->opt.cipso)
2235                 res = cipso_v4_getattr(opt->opt.__data +
2236                                                 opt->opt.cipso -
2237                                                 sizeof(struct iphdr),
2238                                        secattr);
2239         rcu_read_unlock();
2240         return res;
2241 }
2242 
2243 /**
2244  * cipso_v4_skbuff_setattr - Set the CIPSO option on a packet
2245  * @skb: the packet
2246  * @secattr: the security attributes
2247  *
2248  * Description:
2249  * Set the CIPSO option on the given packet based on the security attributes.
2250  * Returns a pointer to the IP header on success and NULL on failure.
2251  *
2252  */
2253 int cipso_v4_skbuff_setattr(struct sk_buff *skb,
2254                             const struct cipso_v4_doi *doi_def,
2255                             const struct netlbl_lsm_secattr *secattr)
2256 {
2257         int ret_val;
2258         struct iphdr *iph;
2259         struct ip_options *opt = &IPCB(skb)->opt;
2260         unsigned char buf[CIPSO_V4_OPT_LEN_MAX];
2261         u32 buf_len = CIPSO_V4_OPT_LEN_MAX;
2262         u32 opt_len;
2263         int len_delta;
2264 
2265         ret_val = cipso_v4_genopt(buf, buf_len, doi_def, secattr);
2266         if (ret_val < 0)
2267                 return ret_val;
2268         buf_len = ret_val;
2269         opt_len = (buf_len + 3) & ~3;
2270 
2271         /* we overwrite any existing options to ensure that we have enough
2272          * room for the CIPSO option, the reason is that we _need_ to guarantee
2273          * that the security label is applied to the packet - we do the same
2274          * thing when using the socket options and it hasn't caused a problem,
2275          * if we need to we can always revisit this choice later */
2276 
2277         len_delta = opt_len - opt->optlen;
2278         /* if we don't ensure enough headroom we could panic on the skb_push()
2279          * call below so make sure we have enough, we are also "mangling" the
2280          * packet so we should probably do a copy-on-write call anyway */
2281         ret_val = skb_cow(skb, skb_headroom(skb) + len_delta);
2282         if (ret_val < 0)
2283                 return ret_val;
2284 
2285         if (len_delta > 0) {
2286                 /* we assume that the header + opt->optlen have already been
2287                  * "pushed" in ip_options_build() or similar */
2288                 iph = ip_hdr(skb);
2289                 skb_push(skb, len_delta);
2290                 memmove((char *)iph - len_delta, iph, iph->ihl << 2);
2291                 skb_reset_network_header(skb);
2292                 iph = ip_hdr(skb);
2293         } else if (len_delta < 0) {
2294                 iph = ip_hdr(skb);
2295                 memset(iph + 1, IPOPT_NOP, opt->optlen);
2296         } else
2297                 iph = ip_hdr(skb);
2298 
2299         if (opt->optlen > 0)
2300                 memset(opt, 0, sizeof(*opt));
2301         opt->optlen = opt_len;
2302         opt->cipso = sizeof(struct iphdr);
2303         opt->is_changed = 1;
2304 
2305         /* we have to do the following because we are being called from a
2306          * netfilter hook which means the packet already has had the header
2307          * fields populated and the checksum calculated - yes this means we
2308          * are doing more work than needed but we do it to keep the core
2309          * stack clean and tidy */
2310         memcpy(iph + 1, buf, buf_len);
2311         if (opt_len > buf_len)
2312                 memset((char *)(iph + 1) + buf_len, 0, opt_len - buf_len);
2313         if (len_delta != 0) {
2314                 iph->ihl = 5 + (opt_len >> 2);
2315                 iph->tot_len = htons(skb->len);
2316         }
2317         ip_send_check(iph);
2318 
2319         return 0;
2320 }
2321 
2322 /**
2323  * cipso_v4_skbuff_delattr - Delete any CIPSO options from a packet
2324  * @skb: the packet
2325  *
2326  * Description:
2327  * Removes any and all CIPSO options from the given packet.  Returns zero on
2328  * success, negative values on failure.
2329  *
2330  */
2331 int cipso_v4_skbuff_delattr(struct sk_buff *skb)
2332 {
2333         int ret_val;
2334         struct iphdr *iph;
2335         struct ip_options *opt = &IPCB(skb)->opt;
2336         unsigned char *cipso_ptr;
2337 
2338         if (opt->cipso == 0)
2339                 return 0;
2340 
2341         /* since we are changing the packet we should make a copy */
2342         ret_val = skb_cow(skb, skb_headroom(skb));
2343         if (ret_val < 0)
2344                 return ret_val;
2345 
2346         /* the easiest thing to do is just replace the cipso option with noop
2347          * options since we don't change the size of the packet, although we
2348          * still need to recalculate the checksum */
2349 
2350         iph = ip_hdr(skb);
2351         cipso_ptr = (unsigned char *)iph + opt->cipso;
2352         memset(cipso_ptr, IPOPT_NOOP, cipso_ptr[1]);
2353         opt->cipso = 0;
2354         opt->is_changed = 1;
2355 
2356         ip_send_check(iph);
2357 
2358         return 0;
2359 }
2360 
2361 /*
2362  * Setup Functions
2363  */
2364 
2365 /**
2366  * cipso_v4_init - Initialize the CIPSO module
2367  *
2368  * Description:
2369  * Initialize the CIPSO module and prepare it for use.  Returns zero on success
2370  * and negative values on failure.
2371  *
2372  */
2373 static int __init cipso_v4_init(void)
2374 {
2375         int ret_val;
2376 
2377         ret_val = cipso_v4_cache_init();
2378         if (ret_val != 0)
2379                 panic("Failed to initialize the CIPSO/IPv4 cache (%d)\n",
2380                       ret_val);
2381 
2382         return 0;
2383 }
2384 
2385 subsys_initcall(cipso_v4_init);
2386 

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