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TOMOYO Linux Cross Reference
Linux/kernel/audit_tree.c

Version: ~ [ linux-5.2-rc6 ] ~ [ linux-5.1.15 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.56 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.130 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.183 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.183 ] ~ [ 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-3.16.69 ] ~ [ 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         chunk->mark.mask = FS_IN_IGNORED;
158         return chunk;
159 }
160 
161 enum {HASH_SIZE = 128};
162 static struct list_head chunk_hash_heads[HASH_SIZE];
163 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
164 
165 static inline struct list_head *chunk_hash(const struct inode *inode)
166 {
167         unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
168         return chunk_hash_heads + n % HASH_SIZE;
169 }
170 
171 /* hash_lock & entry->lock is held by caller */
172 static void insert_hash(struct audit_chunk *chunk)
173 {
174         struct fsnotify_mark *entry = &chunk->mark;
175         struct list_head *list;
176 
177         if (!entry->i.inode)
178                 return;
179         list = chunk_hash(entry->i.inode);
180         list_add_rcu(&chunk->hash, list);
181 }
182 
183 /* called under rcu_read_lock */
184 struct audit_chunk *audit_tree_lookup(const struct inode *inode)
185 {
186         struct list_head *list = chunk_hash(inode);
187         struct audit_chunk *p;
188 
189         list_for_each_entry_rcu(p, list, hash) {
190                 /* mark.inode may have gone NULL, but who cares? */
191                 if (p->mark.i.inode == inode) {
192                         atomic_long_inc(&p->refs);
193                         return p;
194                 }
195         }
196         return NULL;
197 }
198 
199 int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
200 {
201         int n;
202         for (n = 0; n < chunk->count; n++)
203                 if (chunk->owners[n].owner == tree)
204                         return 1;
205         return 0;
206 }
207 
208 /* tagging and untagging inodes with trees */
209 
210 static struct audit_chunk *find_chunk(struct node *p)
211 {
212         int index = p->index & ~(1U<<31);
213         p -= index;
214         return container_of(p, struct audit_chunk, owners[0]);
215 }
216 
217 static void untag_chunk(struct node *p)
218 {
219         struct audit_chunk *chunk = find_chunk(p);
220         struct fsnotify_mark *entry = &chunk->mark;
221         struct audit_chunk *new = NULL;
222         struct audit_tree *owner;
223         int size = chunk->count - 1;
224         int i, j;
225 
226         fsnotify_get_mark(entry);
227 
228         spin_unlock(&hash_lock);
229 
230         if (size)
231                 new = alloc_chunk(size);
232 
233         spin_lock(&entry->lock);
234         if (chunk->dead || !entry->i.inode) {
235                 spin_unlock(&entry->lock);
236                 if (new)
237                         free_chunk(new);
238                 goto out;
239         }
240 
241         owner = p->owner;
242 
243         if (!size) {
244                 chunk->dead = 1;
245                 spin_lock(&hash_lock);
246                 list_del_init(&chunk->trees);
247                 if (owner->root == chunk)
248                         owner->root = NULL;
249                 list_del_init(&p->list);
250                 list_del_rcu(&chunk->hash);
251                 spin_unlock(&hash_lock);
252                 spin_unlock(&entry->lock);
253                 fsnotify_destroy_mark(entry);
254                 goto out;
255         }
256 
257         if (!new)
258                 goto Fallback;
259 
260         fsnotify_duplicate_mark(&new->mark, entry);
261         if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.i.inode, NULL, 1)) {
262                 fsnotify_put_mark(&new->mark);
263                 goto Fallback;
264         }
265 
266         chunk->dead = 1;
267         spin_lock(&hash_lock);
268         list_replace_init(&chunk->trees, &new->trees);
269         if (owner->root == chunk) {
270                 list_del_init(&owner->same_root);
271                 owner->root = NULL;
272         }
273 
274         for (i = j = 0; j <= size; i++, j++) {
275                 struct audit_tree *s;
276                 if (&chunk->owners[j] == p) {
277                         list_del_init(&p->list);
278                         i--;
279                         continue;
280                 }
281                 s = chunk->owners[j].owner;
282                 new->owners[i].owner = s;
283                 new->owners[i].index = chunk->owners[j].index - j + i;
284                 if (!s) /* result of earlier fallback */
285                         continue;
286                 get_tree(s);
287                 list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
288         }
289 
290         list_replace_rcu(&chunk->hash, &new->hash);
291         list_for_each_entry(owner, &new->trees, same_root)
292                 owner->root = new;
293         spin_unlock(&hash_lock);
294         spin_unlock(&entry->lock);
295         fsnotify_destroy_mark(entry);
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_get_mark(entry);
335                 fsnotify_destroy_mark(entry);
336                 fsnotify_put_mark(entry);
337                 return 0;
338         }
339         chunk->owners[0].index = (1U << 31);
340         chunk->owners[0].owner = tree;
341         get_tree(tree);
342         list_add(&chunk->owners[0].list, &tree->chunks);
343         if (!tree->root) {
344                 tree->root = chunk;
345                 list_add(&tree->same_root, &chunk->trees);
346         }
347         insert_hash(chunk);
348         spin_unlock(&hash_lock);
349         spin_unlock(&entry->lock);
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_get_mark(chunk_entry);
416                 fsnotify_destroy_mark(chunk_entry);
417 
418                 fsnotify_put_mark(chunk_entry);
419                 fsnotify_put_mark(old_entry);
420                 return 0;
421         }
422         list_replace_init(&old->trees, &chunk->trees);
423         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
424                 struct audit_tree *s = old->owners[n].owner;
425                 p->owner = s;
426                 p->index = old->owners[n].index;
427                 if (!s) /* result of fallback in untag */
428                         continue;
429                 get_tree(s);
430                 list_replace_init(&old->owners[n].list, &p->list);
431         }
432         p->index = (chunk->count - 1) | (1U<<31);
433         p->owner = tree;
434         get_tree(tree);
435         list_add(&p->list, &tree->chunks);
436         list_replace_rcu(&old->hash, &chunk->hash);
437         list_for_each_entry(owner, &chunk->trees, same_root)
438                 owner->root = chunk;
439         old->dead = 1;
440         if (!tree->root) {
441                 tree->root = chunk;
442                 list_add(&tree->same_root, &chunk->trees);
443         }
444         spin_unlock(&hash_lock);
445         spin_unlock(&chunk_entry->lock);
446         spin_unlock(&old_entry->lock);
447         fsnotify_destroy_mark(old_entry);
448         fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
449         return 0;
450 }
451 
452 static void kill_rules(struct audit_tree *tree)
453 {
454         struct audit_krule *rule, *next;
455         struct audit_entry *entry;
456         struct audit_buffer *ab;
457 
458         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
459                 entry = container_of(rule, struct audit_entry, rule);
460 
461                 list_del_init(&rule->rlist);
462                 if (rule->tree) {
463                         /* not a half-baked one */
464                         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
465                         audit_log_format(ab, "op=");
466                         audit_log_string(ab, "remove rule");
467                         audit_log_format(ab, " dir=");
468                         audit_log_untrustedstring(ab, rule->tree->pathname);
469                         audit_log_key(ab, rule->filterkey);
470                         audit_log_format(ab, " list=%d res=1", rule->listnr);
471                         audit_log_end(ab);
472                         rule->tree = NULL;
473                         list_del_rcu(&entry->list);
474                         list_del(&entry->rule.list);
475                         call_rcu(&entry->rcu, audit_free_rule_rcu);
476                 }
477         }
478 }
479 
480 /*
481  * finish killing struct audit_tree
482  */
483 static void prune_one(struct audit_tree *victim)
484 {
485         spin_lock(&hash_lock);
486         while (!list_empty(&victim->chunks)) {
487                 struct node *p;
488 
489                 p = list_entry(victim->chunks.next, struct node, list);
490 
491                 untag_chunk(p);
492         }
493         spin_unlock(&hash_lock);
494         put_tree(victim);
495 }
496 
497 /* trim the uncommitted chunks from tree */
498 
499 static void trim_marked(struct audit_tree *tree)
500 {
501         struct list_head *p, *q;
502         spin_lock(&hash_lock);
503         if (tree->goner) {
504                 spin_unlock(&hash_lock);
505                 return;
506         }
507         /* reorder */
508         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
509                 struct node *node = list_entry(p, struct node, list);
510                 q = p->next;
511                 if (node->index & (1U<<31)) {
512                         list_del_init(p);
513                         list_add(p, &tree->chunks);
514                 }
515         }
516 
517         while (!list_empty(&tree->chunks)) {
518                 struct node *node;
519 
520                 node = list_entry(tree->chunks.next, struct node, list);
521 
522                 /* have we run out of marked? */
523                 if (!(node->index & (1U<<31)))
524                         break;
525 
526                 untag_chunk(node);
527         }
528         if (!tree->root && !tree->goner) {
529                 tree->goner = 1;
530                 spin_unlock(&hash_lock);
531                 mutex_lock(&audit_filter_mutex);
532                 kill_rules(tree);
533                 list_del_init(&tree->list);
534                 mutex_unlock(&audit_filter_mutex);
535                 prune_one(tree);
536         } else {
537                 spin_unlock(&hash_lock);
538         }
539 }
540 
541 static void audit_schedule_prune(void);
542 
543 /* called with audit_filter_mutex */
544 int audit_remove_tree_rule(struct audit_krule *rule)
545 {
546         struct audit_tree *tree;
547         tree = rule->tree;
548         if (tree) {
549                 spin_lock(&hash_lock);
550                 list_del_init(&rule->rlist);
551                 if (list_empty(&tree->rules) && !tree->goner) {
552                         tree->root = NULL;
553                         list_del_init(&tree->same_root);
554                         tree->goner = 1;
555                         list_move(&tree->list, &prune_list);
556                         rule->tree = NULL;
557                         spin_unlock(&hash_lock);
558                         audit_schedule_prune();
559                         return 1;
560                 }
561                 rule->tree = NULL;
562                 spin_unlock(&hash_lock);
563                 return 1;
564         }
565         return 0;
566 }
567 
568 static int compare_root(struct vfsmount *mnt, void *arg)
569 {
570         return mnt->mnt_root->d_inode == arg;
571 }
572 
573 void audit_trim_trees(void)
574 {
575         struct list_head cursor;
576 
577         mutex_lock(&audit_filter_mutex);
578         list_add(&cursor, &tree_list);
579         while (cursor.next != &tree_list) {
580                 struct audit_tree *tree;
581                 struct path path;
582                 struct vfsmount *root_mnt;
583                 struct node *node;
584                 int err;
585 
586                 tree = container_of(cursor.next, struct audit_tree, list);
587                 get_tree(tree);
588                 list_del(&cursor);
589                 list_add(&cursor, &tree->list);
590                 mutex_unlock(&audit_filter_mutex);
591 
592                 err = kern_path(tree->pathname, 0, &path);
593                 if (err)
594                         goto skip_it;
595 
596                 root_mnt = collect_mounts(&path);
597                 path_put(&path);
598                 if (!root_mnt)
599                         goto skip_it;
600 
601                 spin_lock(&hash_lock);
602                 list_for_each_entry(node, &tree->chunks, list) {
603                         struct audit_chunk *chunk = find_chunk(node);
604                         /* this could be NULL if the watch is dying else where... */
605                         struct inode *inode = chunk->mark.i.inode;
606                         node->index |= 1U<<31;
607                         if (iterate_mounts(compare_root, inode, root_mnt))
608                                 node->index &= ~(1U<<31);
609                 }
610                 spin_unlock(&hash_lock);
611                 trim_marked(tree);
612                 drop_collected_mounts(root_mnt);
613 skip_it:
614                 put_tree(tree);
615                 mutex_lock(&audit_filter_mutex);
616         }
617         list_del(&cursor);
618         mutex_unlock(&audit_filter_mutex);
619 }
620 
621 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
622 {
623 
624         if (pathname[0] != '/' ||
625             rule->listnr != AUDIT_FILTER_EXIT ||
626             op != Audit_equal ||
627             rule->inode_f || rule->watch || rule->tree)
628                 return -EINVAL;
629         rule->tree = alloc_tree(pathname);
630         if (!rule->tree)
631                 return -ENOMEM;
632         return 0;
633 }
634 
635 void audit_put_tree(struct audit_tree *tree)
636 {
637         put_tree(tree);
638 }
639 
640 static int tag_mount(struct vfsmount *mnt, void *arg)
641 {
642         return tag_chunk(mnt->mnt_root->d_inode, arg);
643 }
644 
645 /* called with audit_filter_mutex */
646 int audit_add_tree_rule(struct audit_krule *rule)
647 {
648         struct audit_tree *seed = rule->tree, *tree;
649         struct path path;
650         struct vfsmount *mnt;
651         int err;
652 
653         list_for_each_entry(tree, &tree_list, list) {
654                 if (!strcmp(seed->pathname, tree->pathname)) {
655                         put_tree(seed);
656                         rule->tree = tree;
657                         list_add(&rule->rlist, &tree->rules);
658                         return 0;
659                 }
660         }
661         tree = seed;
662         list_add(&tree->list, &tree_list);
663         list_add(&rule->rlist, &tree->rules);
664         /* do not set rule->tree yet */
665         mutex_unlock(&audit_filter_mutex);
666 
667         err = kern_path(tree->pathname, 0, &path);
668         if (err)
669                 goto Err;
670         mnt = collect_mounts(&path);
671         path_put(&path);
672         if (!mnt) {
673                 err = -ENOMEM;
674                 goto Err;
675         }
676 
677         get_tree(tree);
678         err = iterate_mounts(tag_mount, tree, mnt);
679         drop_collected_mounts(mnt);
680 
681         if (!err) {
682                 struct node *node;
683                 spin_lock(&hash_lock);
684                 list_for_each_entry(node, &tree->chunks, list)
685                         node->index &= ~(1U<<31);
686                 spin_unlock(&hash_lock);
687         } else {
688                 trim_marked(tree);
689                 goto Err;
690         }
691 
692         mutex_lock(&audit_filter_mutex);
693         if (list_empty(&rule->rlist)) {
694                 put_tree(tree);
695                 return -ENOENT;
696         }
697         rule->tree = tree;
698         put_tree(tree);
699 
700         return 0;
701 Err:
702         mutex_lock(&audit_filter_mutex);
703         list_del_init(&tree->list);
704         list_del_init(&tree->rules);
705         put_tree(tree);
706         return err;
707 }
708 
709 int audit_tag_tree(char *old, char *new)
710 {
711         struct list_head cursor, barrier;
712         int failed = 0;
713         struct path path1, path2;
714         struct vfsmount *tagged;
715         int err;
716 
717         err = kern_path(new, 0, &path2);
718         if (err)
719                 return err;
720         tagged = collect_mounts(&path2);
721         path_put(&path2);
722         if (!tagged)
723                 return -ENOMEM;
724 
725         err = kern_path(old, 0, &path1);
726         if (err) {
727                 drop_collected_mounts(tagged);
728                 return err;
729         }
730 
731         mutex_lock(&audit_filter_mutex);
732         list_add(&barrier, &tree_list);
733         list_add(&cursor, &barrier);
734 
735         while (cursor.next != &tree_list) {
736                 struct audit_tree *tree;
737                 int good_one = 0;
738 
739                 tree = container_of(cursor.next, struct audit_tree, list);
740                 get_tree(tree);
741                 list_del(&cursor);
742                 list_add(&cursor, &tree->list);
743                 mutex_unlock(&audit_filter_mutex);
744 
745                 err = kern_path(tree->pathname, 0, &path2);
746                 if (!err) {
747                         good_one = path_is_under(&path1, &path2);
748                         path_put(&path2);
749                 }
750 
751                 if (!good_one) {
752                         put_tree(tree);
753                         mutex_lock(&audit_filter_mutex);
754                         continue;
755                 }
756 
757                 failed = iterate_mounts(tag_mount, tree, tagged);
758                 if (failed) {
759                         put_tree(tree);
760                         mutex_lock(&audit_filter_mutex);
761                         break;
762                 }
763 
764                 mutex_lock(&audit_filter_mutex);
765                 spin_lock(&hash_lock);
766                 if (!tree->goner) {
767                         list_del(&tree->list);
768                         list_add(&tree->list, &tree_list);
769                 }
770                 spin_unlock(&hash_lock);
771                 put_tree(tree);
772         }
773 
774         while (barrier.prev != &tree_list) {
775                 struct audit_tree *tree;
776 
777                 tree = container_of(barrier.prev, struct audit_tree, list);
778                 get_tree(tree);
779                 list_del(&tree->list);
780                 list_add(&tree->list, &barrier);
781                 mutex_unlock(&audit_filter_mutex);
782 
783                 if (!failed) {
784                         struct node *node;
785                         spin_lock(&hash_lock);
786                         list_for_each_entry(node, &tree->chunks, list)
787                                 node->index &= ~(1U<<31);
788                         spin_unlock(&hash_lock);
789                 } else {
790                         trim_marked(tree);
791                 }
792 
793                 put_tree(tree);
794                 mutex_lock(&audit_filter_mutex);
795         }
796         list_del(&barrier);
797         list_del(&cursor);
798         mutex_unlock(&audit_filter_mutex);
799         path_put(&path1);
800         drop_collected_mounts(tagged);
801         return failed;
802 }
803 
804 /*
805  * That gets run when evict_chunk() ends up needing to kill audit_tree.
806  * Runs from a separate thread.
807  */
808 static int prune_tree_thread(void *unused)
809 {
810         mutex_lock(&audit_cmd_mutex);
811         mutex_lock(&audit_filter_mutex);
812 
813         while (!list_empty(&prune_list)) {
814                 struct audit_tree *victim;
815 
816                 victim = list_entry(prune_list.next, struct audit_tree, list);
817                 list_del_init(&victim->list);
818 
819                 mutex_unlock(&audit_filter_mutex);
820 
821                 prune_one(victim);
822 
823                 mutex_lock(&audit_filter_mutex);
824         }
825 
826         mutex_unlock(&audit_filter_mutex);
827         mutex_unlock(&audit_cmd_mutex);
828         return 0;
829 }
830 
831 static void audit_schedule_prune(void)
832 {
833         kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
834 }
835 
836 /*
837  * ... and that one is done if evict_chunk() decides to delay until the end
838  * of syscall.  Runs synchronously.
839  */
840 void audit_kill_trees(struct list_head *list)
841 {
842         mutex_lock(&audit_cmd_mutex);
843         mutex_lock(&audit_filter_mutex);
844 
845         while (!list_empty(list)) {
846                 struct audit_tree *victim;
847 
848                 victim = list_entry(list->next, struct audit_tree, list);
849                 kill_rules(victim);
850                 list_del_init(&victim->list);
851 
852                 mutex_unlock(&audit_filter_mutex);
853 
854                 prune_one(victim);
855 
856                 mutex_lock(&audit_filter_mutex);
857         }
858 
859         mutex_unlock(&audit_filter_mutex);
860         mutex_unlock(&audit_cmd_mutex);
861 }
862 
863 /*
864  *  Here comes the stuff asynchronous to auditctl operations
865  */
866 
867 static void evict_chunk(struct audit_chunk *chunk)
868 {
869         struct audit_tree *owner;
870         struct list_head *postponed = audit_killed_trees();
871         int need_prune = 0;
872         int n;
873 
874         if (chunk->dead)
875                 return;
876 
877         chunk->dead = 1;
878         mutex_lock(&audit_filter_mutex);
879         spin_lock(&hash_lock);
880         while (!list_empty(&chunk->trees)) {
881                 owner = list_entry(chunk->trees.next,
882                                    struct audit_tree, same_root);
883                 owner->goner = 1;
884                 owner->root = NULL;
885                 list_del_init(&owner->same_root);
886                 spin_unlock(&hash_lock);
887                 if (!postponed) {
888                         kill_rules(owner);
889                         list_move(&owner->list, &prune_list);
890                         need_prune = 1;
891                 } else {
892                         list_move(&owner->list, postponed);
893                 }
894                 spin_lock(&hash_lock);
895         }
896         list_del_rcu(&chunk->hash);
897         for (n = 0; n < chunk->count; n++)
898                 list_del_init(&chunk->owners[n].list);
899         spin_unlock(&hash_lock);
900         if (need_prune)
901                 audit_schedule_prune();
902         mutex_unlock(&audit_filter_mutex);
903 }
904 
905 static int audit_tree_handle_event(struct fsnotify_group *group,
906                                    struct fsnotify_mark *inode_mark,
907                                    struct fsnotify_mark *vfsmonut_mark,
908                                    struct fsnotify_event *event)
909 {
910         BUG();
911         return -EOPNOTSUPP;
912 }
913 
914 static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
915 {
916         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
917 
918         evict_chunk(chunk);
919         fsnotify_put_mark(entry);
920 }
921 
922 static bool audit_tree_send_event(struct fsnotify_group *group, struct inode *inode,
923                                   struct fsnotify_mark *inode_mark,
924                                   struct fsnotify_mark *vfsmount_mark,
925                                   __u32 mask, void *data, int data_type)
926 {
927         return false;
928 }
929 
930 static const struct fsnotify_ops audit_tree_ops = {
931         .handle_event = audit_tree_handle_event,
932         .should_send_event = audit_tree_send_event,
933         .free_group_priv = NULL,
934         .free_event_priv = NULL,
935         .freeing_mark = audit_tree_freeing_mark,
936 };
937 
938 static int __init audit_tree_init(void)
939 {
940         int i;
941 
942         audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
943         if (IS_ERR(audit_tree_group))
944                 audit_panic("cannot initialize fsnotify group for rectree watches");
945 
946         for (i = 0; i < HASH_SIZE; i++)
947                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
948 
949         return 0;
950 }
951 __initcall(audit_tree_init);
952 

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