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Linux/net/ipv6/calipso.c

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

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