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TOMOYO Linux Cross Reference
Linux/kernel/audit_tree.c

Version: ~ [ linux-5.2-rc4 ] ~ [ linux-5.1.9 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.50 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.125 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.181 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.181 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.68 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.39.4 ] ~ [ linux-2.6.38.8 ] ~ [ linux-2.6.37.6 ] ~ [ linux-2.6.36.4 ] ~ [ linux-2.6.35.14 ] ~ [ linux-2.6.34.15 ] ~ [ linux-2.6.33.20 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  1 #include "audit.h"
  2 #include <linux/fsnotify_backend.h>
  3 #include <linux/namei.h>
  4 #include <linux/mount.h>
  5 #include <linux/kthread.h>
  6 #include <linux/slab.h>
  7 
  8 struct audit_tree;
  9 struct audit_chunk;
 10 
 11 struct audit_tree {
 12         atomic_t count;
 13         int goner;
 14         struct audit_chunk *root;
 15         struct list_head chunks;
 16         struct list_head rules;
 17         struct list_head list;
 18         struct list_head same_root;
 19         struct rcu_head head;
 20         char pathname[];
 21 };
 22 
 23 struct audit_chunk {
 24         struct list_head hash;
 25         struct fsnotify_mark mark;
 26         struct list_head trees;         /* with root here */
 27         int dead;
 28         int count;
 29         atomic_long_t refs;
 30         struct rcu_head head;
 31         struct node {
 32                 struct list_head list;
 33                 struct audit_tree *owner;
 34                 unsigned index;         /* index; upper bit indicates 'will prune' */
 35         } owners[];
 36 };
 37 
 38 static LIST_HEAD(tree_list);
 39 static LIST_HEAD(prune_list);
 40 
 41 /*
 42  * One struct chunk is attached to each inode of interest.
 43  * We replace struct chunk on tagging/untagging.
 44  * Rules have pointer to struct audit_tree.
 45  * Rules have struct list_head rlist forming a list of rules over
 46  * the same tree.
 47  * References to struct chunk are collected at audit_inode{,_child}()
 48  * time and used in AUDIT_TREE rule matching.
 49  * These references are dropped at the same time we are calling
 50  * audit_free_names(), etc.
 51  *
 52  * Cyclic lists galore:
 53  * tree.chunks anchors chunk.owners[].list                      hash_lock
 54  * tree.rules anchors rule.rlist                                audit_filter_mutex
 55  * chunk.trees anchors tree.same_root                           hash_lock
 56  * chunk.hash is a hash with middle bits of watch.inode as
 57  * a hash function.                                             RCU, hash_lock
 58  *
 59  * tree is refcounted; one reference for "some rules on rules_list refer to
 60  * it", one for each chunk with pointer to it.
 61  *
 62  * chunk is refcounted by embedded fsnotify_mark + .refs (non-zero refcount
 63  * of watch contributes 1 to .refs).
 64  *
 65  * node.index allows to get from node.list to containing chunk.
 66  * MSB of that sucker is stolen to mark taggings that we might have to
 67  * revert - several operations have very unpleasant cleanup logics and
 68  * that makes a difference.  Some.
 69  */
 70 
 71 static struct fsnotify_group *audit_tree_group;
 72 
 73 static struct audit_tree *alloc_tree(const char *s)
 74 {
 75         struct audit_tree *tree;
 76 
 77         tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
 78         if (tree) {
 79                 atomic_set(&tree->count, 1);
 80                 tree->goner = 0;
 81                 INIT_LIST_HEAD(&tree->chunks);
 82                 INIT_LIST_HEAD(&tree->rules);
 83                 INIT_LIST_HEAD(&tree->list);
 84                 INIT_LIST_HEAD(&tree->same_root);
 85                 tree->root = NULL;
 86                 strcpy(tree->pathname, s);
 87         }
 88         return tree;
 89 }
 90 
 91 static inline void get_tree(struct audit_tree *tree)
 92 {
 93         atomic_inc(&tree->count);
 94 }
 95 
 96 static inline void put_tree(struct audit_tree *tree)
 97 {
 98         if (atomic_dec_and_test(&tree->count))
 99                 kfree_rcu(tree, head);
100 }
101 
102 /* to avoid bringing the entire thing in audit.h */
103 const char *audit_tree_path(struct audit_tree *tree)
104 {
105         return tree->pathname;
106 }
107 
108 static void free_chunk(struct audit_chunk *chunk)
109 {
110         int i;
111 
112         for (i = 0; i < chunk->count; i++) {
113                 if (chunk->owners[i].owner)
114                         put_tree(chunk->owners[i].owner);
115         }
116         kfree(chunk);
117 }
118 
119 void audit_put_chunk(struct audit_chunk *chunk)
120 {
121         if (atomic_long_dec_and_test(&chunk->refs))
122                 free_chunk(chunk);
123 }
124 
125 static void __put_chunk(struct rcu_head *rcu)
126 {
127         struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
128         audit_put_chunk(chunk);
129 }
130 
131 static void audit_tree_destroy_watch(struct fsnotify_mark *entry)
132 {
133         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
134         call_rcu(&chunk->head, __put_chunk);
135 }
136 
137 static struct audit_chunk *alloc_chunk(int count)
138 {
139         struct audit_chunk *chunk;
140         size_t size;
141         int i;
142 
143         size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
144         chunk = kzalloc(size, GFP_KERNEL);
145         if (!chunk)
146                 return NULL;
147 
148         INIT_LIST_HEAD(&chunk->hash);
149         INIT_LIST_HEAD(&chunk->trees);
150         chunk->count = count;
151         atomic_long_set(&chunk->refs, 1);
152         for (i = 0; i < count; i++) {
153                 INIT_LIST_HEAD(&chunk->owners[i].list);
154                 chunk->owners[i].index = i;
155         }
156         fsnotify_init_mark(&chunk->mark, audit_tree_destroy_watch);
157         return chunk;
158 }
159 
160 enum {HASH_SIZE = 128};
161 static struct list_head chunk_hash_heads[HASH_SIZE];
162 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
163 
164 static inline struct list_head *chunk_hash(const struct inode *inode)
165 {
166         unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
167         return chunk_hash_heads + n % HASH_SIZE;
168 }
169 
170 /* hash_lock & entry->lock is held by caller */
171 static void insert_hash(struct audit_chunk *chunk)
172 {
173         struct fsnotify_mark *entry = &chunk->mark;
174         struct list_head *list;
175 
176         if (!entry->i.inode)
177                 return;
178         list = chunk_hash(entry->i.inode);
179         list_add_rcu(&chunk->hash, list);
180 }
181 
182 /* called under rcu_read_lock */
183 struct audit_chunk *audit_tree_lookup(const struct inode *inode)
184 {
185         struct list_head *list = chunk_hash(inode);
186         struct audit_chunk *p;
187 
188         list_for_each_entry_rcu(p, list, hash) {
189                 /* mark.inode may have gone NULL, but who cares? */
190                 if (p->mark.i.inode == inode) {
191                         atomic_long_inc(&p->refs);
192                         return p;
193                 }
194         }
195         return NULL;
196 }
197 
198 int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
199 {
200         int n;
201         for (n = 0; n < chunk->count; n++)
202                 if (chunk->owners[n].owner == tree)
203                         return 1;
204         return 0;
205 }
206 
207 /* tagging and untagging inodes with trees */
208 
209 static struct audit_chunk *find_chunk(struct node *p)
210 {
211         int index = p->index & ~(1U<<31);
212         p -= index;
213         return container_of(p, struct audit_chunk, owners[0]);
214 }
215 
216 static void untag_chunk(struct node *p)
217 {
218         struct audit_chunk *chunk = find_chunk(p);
219         struct fsnotify_mark *entry = &chunk->mark;
220         struct audit_chunk *new = NULL;
221         struct audit_tree *owner;
222         int size = chunk->count - 1;
223         int i, j;
224 
225         fsnotify_get_mark(entry);
226 
227         spin_unlock(&hash_lock);
228 
229         if (size)
230                 new = alloc_chunk(size);
231 
232         spin_lock(&entry->lock);
233         if (chunk->dead || !entry->i.inode) {
234                 spin_unlock(&entry->lock);
235                 if (new)
236                         free_chunk(new);
237                 goto out;
238         }
239 
240         owner = p->owner;
241 
242         if (!size) {
243                 chunk->dead = 1;
244                 spin_lock(&hash_lock);
245                 list_del_init(&chunk->trees);
246                 if (owner->root == chunk)
247                         owner->root = NULL;
248                 list_del_init(&p->list);
249                 list_del_rcu(&chunk->hash);
250                 spin_unlock(&hash_lock);
251                 spin_unlock(&entry->lock);
252                 fsnotify_destroy_mark(entry, audit_tree_group);
253                 goto out;
254         }
255 
256         if (!new)
257                 goto Fallback;
258 
259         fsnotify_duplicate_mark(&new->mark, entry);
260         if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.i.inode, NULL, 1)) {
261                 fsnotify_put_mark(&new->mark);
262                 goto Fallback;
263         }
264 
265         chunk->dead = 1;
266         spin_lock(&hash_lock);
267         list_replace_init(&chunk->trees, &new->trees);
268         if (owner->root == chunk) {
269                 list_del_init(&owner->same_root);
270                 owner->root = NULL;
271         }
272 
273         for (i = j = 0; j <= size; i++, j++) {
274                 struct audit_tree *s;
275                 if (&chunk->owners[j] == p) {
276                         list_del_init(&p->list);
277                         i--;
278                         continue;
279                 }
280                 s = chunk->owners[j].owner;
281                 new->owners[i].owner = s;
282                 new->owners[i].index = chunk->owners[j].index - j + i;
283                 if (!s) /* result of earlier fallback */
284                         continue;
285                 get_tree(s);
286                 list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
287         }
288 
289         list_replace_rcu(&chunk->hash, &new->hash);
290         list_for_each_entry(owner, &new->trees, same_root)
291                 owner->root = new;
292         spin_unlock(&hash_lock);
293         spin_unlock(&entry->lock);
294         fsnotify_destroy_mark(entry, audit_tree_group);
295         fsnotify_put_mark(&new->mark);  /* drop initial reference */
296         goto out;
297 
298 Fallback:
299         // do the best we can
300         spin_lock(&hash_lock);
301         if (owner->root == chunk) {
302                 list_del_init(&owner->same_root);
303                 owner->root = NULL;
304         }
305         list_del_init(&p->list);
306         p->owner = NULL;
307         put_tree(owner);
308         spin_unlock(&hash_lock);
309         spin_unlock(&entry->lock);
310 out:
311         fsnotify_put_mark(entry);
312         spin_lock(&hash_lock);
313 }
314 
315 static int create_chunk(struct inode *inode, struct audit_tree *tree)
316 {
317         struct fsnotify_mark *entry;
318         struct audit_chunk *chunk = alloc_chunk(1);
319         if (!chunk)
320                 return -ENOMEM;
321 
322         entry = &chunk->mark;
323         if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) {
324                 fsnotify_put_mark(entry);
325                 return -ENOSPC;
326         }
327 
328         spin_lock(&entry->lock);
329         spin_lock(&hash_lock);
330         if (tree->goner) {
331                 spin_unlock(&hash_lock);
332                 chunk->dead = 1;
333                 spin_unlock(&entry->lock);
334                 fsnotify_destroy_mark(entry, audit_tree_group);
335                 fsnotify_put_mark(entry);
336                 return 0;
337         }
338         chunk->owners[0].index = (1U << 31);
339         chunk->owners[0].owner = tree;
340         get_tree(tree);
341         list_add(&chunk->owners[0].list, &tree->chunks);
342         if (!tree->root) {
343                 tree->root = chunk;
344                 list_add(&tree->same_root, &chunk->trees);
345         }
346         insert_hash(chunk);
347         spin_unlock(&hash_lock);
348         spin_unlock(&entry->lock);
349         fsnotify_put_mark(entry);       /* drop initial reference */
350         return 0;
351 }
352 
353 /* the first tagged inode becomes root of tree */
354 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
355 {
356         struct fsnotify_mark *old_entry, *chunk_entry;
357         struct audit_tree *owner;
358         struct audit_chunk *chunk, *old;
359         struct node *p;
360         int n;
361 
362         old_entry = fsnotify_find_inode_mark(audit_tree_group, inode);
363         if (!old_entry)
364                 return create_chunk(inode, tree);
365 
366         old = container_of(old_entry, struct audit_chunk, mark);
367 
368         /* are we already there? */
369         spin_lock(&hash_lock);
370         for (n = 0; n < old->count; n++) {
371                 if (old->owners[n].owner == tree) {
372                         spin_unlock(&hash_lock);
373                         fsnotify_put_mark(old_entry);
374                         return 0;
375                 }
376         }
377         spin_unlock(&hash_lock);
378 
379         chunk = alloc_chunk(old->count + 1);
380         if (!chunk) {
381                 fsnotify_put_mark(old_entry);
382                 return -ENOMEM;
383         }
384 
385         chunk_entry = &chunk->mark;
386 
387         spin_lock(&old_entry->lock);
388         if (!old_entry->i.inode) {
389                 /* old_entry is being shot, lets just lie */
390                 spin_unlock(&old_entry->lock);
391                 fsnotify_put_mark(old_entry);
392                 free_chunk(chunk);
393                 return -ENOENT;
394         }
395 
396         fsnotify_duplicate_mark(chunk_entry, old_entry);
397         if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->i.inode, NULL, 1)) {
398                 spin_unlock(&old_entry->lock);
399                 fsnotify_put_mark(chunk_entry);
400                 fsnotify_put_mark(old_entry);
401                 return -ENOSPC;
402         }
403 
404         /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
405         spin_lock(&chunk_entry->lock);
406         spin_lock(&hash_lock);
407 
408         /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
409         if (tree->goner) {
410                 spin_unlock(&hash_lock);
411                 chunk->dead = 1;
412                 spin_unlock(&chunk_entry->lock);
413                 spin_unlock(&old_entry->lock);
414 
415                 fsnotify_destroy_mark(chunk_entry, audit_tree_group);
416 
417                 fsnotify_put_mark(chunk_entry);
418                 fsnotify_put_mark(old_entry);
419                 return 0;
420         }
421         list_replace_init(&old->trees, &chunk->trees);
422         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
423                 struct audit_tree *s = old->owners[n].owner;
424                 p->owner = s;
425                 p->index = old->owners[n].index;
426                 if (!s) /* result of fallback in untag */
427                         continue;
428                 get_tree(s);
429                 list_replace_init(&old->owners[n].list, &p->list);
430         }
431         p->index = (chunk->count - 1) | (1U<<31);
432         p->owner = tree;
433         get_tree(tree);
434         list_add(&p->list, &tree->chunks);
435         list_replace_rcu(&old->hash, &chunk->hash);
436         list_for_each_entry(owner, &chunk->trees, same_root)
437                 owner->root = chunk;
438         old->dead = 1;
439         if (!tree->root) {
440                 tree->root = chunk;
441                 list_add(&tree->same_root, &chunk->trees);
442         }
443         spin_unlock(&hash_lock);
444         spin_unlock(&chunk_entry->lock);
445         spin_unlock(&old_entry->lock);
446         fsnotify_destroy_mark(old_entry, audit_tree_group);
447         fsnotify_put_mark(chunk_entry); /* drop initial reference */
448         fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
449         return 0;
450 }
451 
452 static void audit_log_remove_rule(struct audit_krule *rule)
453 {
454         struct audit_buffer *ab;
455 
456         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
457         if (unlikely(!ab))
458                 return;
459         audit_log_format(ab, "op=");
460         audit_log_string(ab, "remove rule");
461         audit_log_format(ab, " dir=");
462         audit_log_untrustedstring(ab, rule->tree->pathname);
463         audit_log_key(ab, rule->filterkey);
464         audit_log_format(ab, " list=%d res=1", rule->listnr);
465         audit_log_end(ab);
466 }
467 
468 static void kill_rules(struct audit_tree *tree)
469 {
470         struct audit_krule *rule, *next;
471         struct audit_entry *entry;
472 
473         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
474                 entry = container_of(rule, struct audit_entry, rule);
475 
476                 list_del_init(&rule->rlist);
477                 if (rule->tree) {
478                         /* not a half-baked one */
479                         audit_log_remove_rule(rule);
480                         rule->tree = NULL;
481                         list_del_rcu(&entry->list);
482                         list_del(&entry->rule.list);
483                         call_rcu(&entry->rcu, audit_free_rule_rcu);
484                 }
485         }
486 }
487 
488 /*
489  * finish killing struct audit_tree
490  */
491 static void prune_one(struct audit_tree *victim)
492 {
493         spin_lock(&hash_lock);
494         while (!list_empty(&victim->chunks)) {
495                 struct node *p;
496 
497                 p = list_entry(victim->chunks.next, struct node, list);
498 
499                 untag_chunk(p);
500         }
501         spin_unlock(&hash_lock);
502         put_tree(victim);
503 }
504 
505 /* trim the uncommitted chunks from tree */
506 
507 static void trim_marked(struct audit_tree *tree)
508 {
509         struct list_head *p, *q;
510         spin_lock(&hash_lock);
511         if (tree->goner) {
512                 spin_unlock(&hash_lock);
513                 return;
514         }
515         /* reorder */
516         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
517                 struct node *node = list_entry(p, struct node, list);
518                 q = p->next;
519                 if (node->index & (1U<<31)) {
520                         list_del_init(p);
521                         list_add(p, &tree->chunks);
522                 }
523         }
524 
525         while (!list_empty(&tree->chunks)) {
526                 struct node *node;
527 
528                 node = list_entry(tree->chunks.next, struct node, list);
529 
530                 /* have we run out of marked? */
531                 if (!(node->index & (1U<<31)))
532                         break;
533 
534                 untag_chunk(node);
535         }
536         if (!tree->root && !tree->goner) {
537                 tree->goner = 1;
538                 spin_unlock(&hash_lock);
539                 mutex_lock(&audit_filter_mutex);
540                 kill_rules(tree);
541                 list_del_init(&tree->list);
542                 mutex_unlock(&audit_filter_mutex);
543                 prune_one(tree);
544         } else {
545                 spin_unlock(&hash_lock);
546         }
547 }
548 
549 static void audit_schedule_prune(void);
550 
551 /* called with audit_filter_mutex */
552 int audit_remove_tree_rule(struct audit_krule *rule)
553 {
554         struct audit_tree *tree;
555         tree = rule->tree;
556         if (tree) {
557                 spin_lock(&hash_lock);
558                 list_del_init(&rule->rlist);
559                 if (list_empty(&tree->rules) && !tree->goner) {
560                         tree->root = NULL;
561                         list_del_init(&tree->same_root);
562                         tree->goner = 1;
563                         list_move(&tree->list, &prune_list);
564                         rule->tree = NULL;
565                         spin_unlock(&hash_lock);
566                         audit_schedule_prune();
567                         return 1;
568                 }
569                 rule->tree = NULL;
570                 spin_unlock(&hash_lock);
571                 return 1;
572         }
573         return 0;
574 }
575 
576 static int compare_root(struct vfsmount *mnt, void *arg)
577 {
578         return mnt->mnt_root->d_inode == arg;
579 }
580 
581 void audit_trim_trees(void)
582 {
583         struct list_head cursor;
584 
585         mutex_lock(&audit_filter_mutex);
586         list_add(&cursor, &tree_list);
587         while (cursor.next != &tree_list) {
588                 struct audit_tree *tree;
589                 struct path path;
590                 struct vfsmount *root_mnt;
591                 struct node *node;
592                 int err;
593 
594                 tree = container_of(cursor.next, struct audit_tree, list);
595                 get_tree(tree);
596                 list_del(&cursor);
597                 list_add(&cursor, &tree->list);
598                 mutex_unlock(&audit_filter_mutex);
599 
600                 err = kern_path(tree->pathname, 0, &path);
601                 if (err)
602                         goto skip_it;
603 
604                 root_mnt = collect_mounts(&path);
605                 path_put(&path);
606                 if (IS_ERR(root_mnt))
607                         goto skip_it;
608 
609                 spin_lock(&hash_lock);
610                 list_for_each_entry(node, &tree->chunks, list) {
611                         struct audit_chunk *chunk = find_chunk(node);
612                         /* this could be NULL if the watch is dying else where... */
613                         struct inode *inode = chunk->mark.i.inode;
614                         node->index |= 1U<<31;
615                         if (iterate_mounts(compare_root, inode, root_mnt))
616                                 node->index &= ~(1U<<31);
617                 }
618                 spin_unlock(&hash_lock);
619                 trim_marked(tree);
620                 drop_collected_mounts(root_mnt);
621 skip_it:
622                 put_tree(tree);
623                 mutex_lock(&audit_filter_mutex);
624         }
625         list_del(&cursor);
626         mutex_unlock(&audit_filter_mutex);
627 }
628 
629 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
630 {
631 
632         if (pathname[0] != '/' ||
633             rule->listnr != AUDIT_FILTER_EXIT ||
634             op != Audit_equal ||
635             rule->inode_f || rule->watch || rule->tree)
636                 return -EINVAL;
637         rule->tree = alloc_tree(pathname);
638         if (!rule->tree)
639                 return -ENOMEM;
640         return 0;
641 }
642 
643 void audit_put_tree(struct audit_tree *tree)
644 {
645         put_tree(tree);
646 }
647 
648 static int tag_mount(struct vfsmount *mnt, void *arg)
649 {
650         return tag_chunk(mnt->mnt_root->d_inode, arg);
651 }
652 
653 /* called with audit_filter_mutex */
654 int audit_add_tree_rule(struct audit_krule *rule)
655 {
656         struct audit_tree *seed = rule->tree, *tree;
657         struct path path;
658         struct vfsmount *mnt;
659         int err;
660 
661         list_for_each_entry(tree, &tree_list, list) {
662                 if (!strcmp(seed->pathname, tree->pathname)) {
663                         put_tree(seed);
664                         rule->tree = tree;
665                         list_add(&rule->rlist, &tree->rules);
666                         return 0;
667                 }
668         }
669         tree = seed;
670         list_add(&tree->list, &tree_list);
671         list_add(&rule->rlist, &tree->rules);
672         /* do not set rule->tree yet */
673         mutex_unlock(&audit_filter_mutex);
674 
675         err = kern_path(tree->pathname, 0, &path);
676         if (err)
677                 goto Err;
678         mnt = collect_mounts(&path);
679         path_put(&path);
680         if (IS_ERR(mnt)) {
681                 err = PTR_ERR(mnt);
682                 goto Err;
683         }
684 
685         get_tree(tree);
686         err = iterate_mounts(tag_mount, tree, mnt);
687         drop_collected_mounts(mnt);
688 
689         if (!err) {
690                 struct node *node;
691                 spin_lock(&hash_lock);
692                 list_for_each_entry(node, &tree->chunks, list)
693                         node->index &= ~(1U<<31);
694                 spin_unlock(&hash_lock);
695         } else {
696                 trim_marked(tree);
697                 goto Err;
698         }
699 
700         mutex_lock(&audit_filter_mutex);
701         if (list_empty(&rule->rlist)) {
702                 put_tree(tree);
703                 return -ENOENT;
704         }
705         rule->tree = tree;
706         put_tree(tree);
707 
708         return 0;
709 Err:
710         mutex_lock(&audit_filter_mutex);
711         list_del_init(&tree->list);
712         list_del_init(&tree->rules);
713         put_tree(tree);
714         return err;
715 }
716 
717 int audit_tag_tree(char *old, char *new)
718 {
719         struct list_head cursor, barrier;
720         int failed = 0;
721         struct path path1, path2;
722         struct vfsmount *tagged;
723         int err;
724 
725         err = kern_path(new, 0, &path2);
726         if (err)
727                 return err;
728         tagged = collect_mounts(&path2);
729         path_put(&path2);
730         if (IS_ERR(tagged))
731                 return PTR_ERR(tagged);
732 
733         err = kern_path(old, 0, &path1);
734         if (err) {
735                 drop_collected_mounts(tagged);
736                 return err;
737         }
738 
739         mutex_lock(&audit_filter_mutex);
740         list_add(&barrier, &tree_list);
741         list_add(&cursor, &barrier);
742 
743         while (cursor.next != &tree_list) {
744                 struct audit_tree *tree;
745                 int good_one = 0;
746 
747                 tree = container_of(cursor.next, struct audit_tree, list);
748                 get_tree(tree);
749                 list_del(&cursor);
750                 list_add(&cursor, &tree->list);
751                 mutex_unlock(&audit_filter_mutex);
752 
753                 err = kern_path(tree->pathname, 0, &path2);
754                 if (!err) {
755                         good_one = path_is_under(&path1, &path2);
756                         path_put(&path2);
757                 }
758 
759                 if (!good_one) {
760                         put_tree(tree);
761                         mutex_lock(&audit_filter_mutex);
762                         continue;
763                 }
764 
765                 failed = iterate_mounts(tag_mount, tree, tagged);
766                 if (failed) {
767                         put_tree(tree);
768                         mutex_lock(&audit_filter_mutex);
769                         break;
770                 }
771 
772                 mutex_lock(&audit_filter_mutex);
773                 spin_lock(&hash_lock);
774                 if (!tree->goner) {
775                         list_del(&tree->list);
776                         list_add(&tree->list, &tree_list);
777                 }
778                 spin_unlock(&hash_lock);
779                 put_tree(tree);
780         }
781 
782         while (barrier.prev != &tree_list) {
783                 struct audit_tree *tree;
784 
785                 tree = container_of(barrier.prev, struct audit_tree, list);
786                 get_tree(tree);
787                 list_del(&tree->list);
788                 list_add(&tree->list, &barrier);
789                 mutex_unlock(&audit_filter_mutex);
790 
791                 if (!failed) {
792                         struct node *node;
793                         spin_lock(&hash_lock);
794                         list_for_each_entry(node, &tree->chunks, list)
795                                 node->index &= ~(1U<<31);
796                         spin_unlock(&hash_lock);
797                 } else {
798                         trim_marked(tree);
799                 }
800 
801                 put_tree(tree);
802                 mutex_lock(&audit_filter_mutex);
803         }
804         list_del(&barrier);
805         list_del(&cursor);
806         mutex_unlock(&audit_filter_mutex);
807         path_put(&path1);
808         drop_collected_mounts(tagged);
809         return failed;
810 }
811 
812 /*
813  * That gets run when evict_chunk() ends up needing to kill audit_tree.
814  * Runs from a separate thread.
815  */
816 static int prune_tree_thread(void *unused)
817 {
818         mutex_lock(&audit_cmd_mutex);
819         mutex_lock(&audit_filter_mutex);
820 
821         while (!list_empty(&prune_list)) {
822                 struct audit_tree *victim;
823 
824                 victim = list_entry(prune_list.next, struct audit_tree, list);
825                 list_del_init(&victim->list);
826 
827                 mutex_unlock(&audit_filter_mutex);
828 
829                 prune_one(victim);
830 
831                 mutex_lock(&audit_filter_mutex);
832         }
833 
834         mutex_unlock(&audit_filter_mutex);
835         mutex_unlock(&audit_cmd_mutex);
836         return 0;
837 }
838 
839 static void audit_schedule_prune(void)
840 {
841         kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
842 }
843 
844 /*
845  * ... and that one is done if evict_chunk() decides to delay until the end
846  * of syscall.  Runs synchronously.
847  */
848 void audit_kill_trees(struct list_head *list)
849 {
850         mutex_lock(&audit_cmd_mutex);
851         mutex_lock(&audit_filter_mutex);
852 
853         while (!list_empty(list)) {
854                 struct audit_tree *victim;
855 
856                 victim = list_entry(list->next, struct audit_tree, list);
857                 kill_rules(victim);
858                 list_del_init(&victim->list);
859 
860                 mutex_unlock(&audit_filter_mutex);
861 
862                 prune_one(victim);
863 
864                 mutex_lock(&audit_filter_mutex);
865         }
866 
867         mutex_unlock(&audit_filter_mutex);
868         mutex_unlock(&audit_cmd_mutex);
869 }
870 
871 /*
872  *  Here comes the stuff asynchronous to auditctl operations
873  */
874 
875 static void evict_chunk(struct audit_chunk *chunk)
876 {
877         struct audit_tree *owner;
878         struct list_head *postponed = audit_killed_trees();
879         int need_prune = 0;
880         int n;
881 
882         if (chunk->dead)
883                 return;
884 
885         chunk->dead = 1;
886         mutex_lock(&audit_filter_mutex);
887         spin_lock(&hash_lock);
888         while (!list_empty(&chunk->trees)) {
889                 owner = list_entry(chunk->trees.next,
890                                    struct audit_tree, same_root);
891                 owner->goner = 1;
892                 owner->root = NULL;
893                 list_del_init(&owner->same_root);
894                 spin_unlock(&hash_lock);
895                 if (!postponed) {
896                         kill_rules(owner);
897                         list_move(&owner->list, &prune_list);
898                         need_prune = 1;
899                 } else {
900                         list_move(&owner->list, postponed);
901                 }
902                 spin_lock(&hash_lock);
903         }
904         list_del_rcu(&chunk->hash);
905         for (n = 0; n < chunk->count; n++)
906                 list_del_init(&chunk->owners[n].list);
907         spin_unlock(&hash_lock);
908         if (need_prune)
909                 audit_schedule_prune();
910         mutex_unlock(&audit_filter_mutex);
911 }
912 
913 static int audit_tree_handle_event(struct fsnotify_group *group,
914                                    struct fsnotify_mark *inode_mark,
915                                    struct fsnotify_mark *vfsmonut_mark,
916                                    struct fsnotify_event *event)
917 {
918         BUG();
919         return -EOPNOTSUPP;
920 }
921 
922 static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
923 {
924         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
925 
926         evict_chunk(chunk);
927 
928         /*
929          * We are guaranteed to have at least one reference to the mark from
930          * either the inode or the caller of fsnotify_destroy_mark().
931          */
932         BUG_ON(atomic_read(&entry->refcnt) < 1);
933 }
934 
935 static bool audit_tree_send_event(struct fsnotify_group *group, struct inode *inode,
936                                   struct fsnotify_mark *inode_mark,
937                                   struct fsnotify_mark *vfsmount_mark,
938                                   __u32 mask, void *data, int data_type)
939 {
940         return false;
941 }
942 
943 static const struct fsnotify_ops audit_tree_ops = {
944         .handle_event = audit_tree_handle_event,
945         .should_send_event = audit_tree_send_event,
946         .free_group_priv = NULL,
947         .free_event_priv = NULL,
948         .freeing_mark = audit_tree_freeing_mark,
949 };
950 
951 static int __init audit_tree_init(void)
952 {
953         int i;
954 
955         audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
956         if (IS_ERR(audit_tree_group))
957                 audit_panic("cannot initialize fsnotify group for rectree watches");
958 
959         for (i = 0; i < HASH_SIZE; i++)
960                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
961 
962         return 0;
963 }
964 __initcall(audit_tree_init);
965 

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