Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/kernel/audit_tree.c

  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 static struct task_struct *prune_thread;
 41 
 42 /*
 43  * One struct chunk is attached to each inode of interest.
 44  * We replace struct chunk on tagging/untagging.
 45  * Rules have pointer to struct audit_tree.
 46  * Rules have struct list_head rlist forming a list of rules over
 47  * the same tree.
 48  * References to struct chunk are collected at audit_inode{,_child}()
 49  * time and used in AUDIT_TREE rule matching.
 50  * These references are dropped at the same time we are calling
 51  * audit_free_names(), etc.
 52  *
 53  * Cyclic lists galore:
 54  * tree.chunks anchors chunk.owners[].list                      hash_lock
 55  * tree.rules anchors rule.rlist                                audit_filter_mutex
 56  * chunk.trees anchors tree.same_root                           hash_lock
 57  * chunk.hash is a hash with middle bits of watch.inode as
 58  * a hash function.                                             RCU, hash_lock
 59  *
 60  * tree is refcounted; one reference for "some rules on rules_list refer to
 61  * it", one for each chunk with pointer to it.
 62  *
 63  * chunk is refcounted by embedded fsnotify_mark + .refs (non-zero refcount
 64  * of watch contributes 1 to .refs).
 65  *
 66  * node.index allows to get from node.list to containing chunk.
 67  * MSB of that sucker is stolen to mark taggings that we might have to
 68  * revert - several operations have very unpleasant cleanup logics and
 69  * that makes a difference.  Some.
 70  */
 71 
 72 static struct fsnotify_group *audit_tree_group;
 73 
 74 static struct audit_tree *alloc_tree(const char *s)
 75 {
 76         struct audit_tree *tree;
 77 
 78         tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
 79         if (tree) {
 80                 atomic_set(&tree->count, 1);
 81                 tree->goner = 0;
 82                 INIT_LIST_HEAD(&tree->chunks);
 83                 INIT_LIST_HEAD(&tree->rules);
 84                 INIT_LIST_HEAD(&tree->list);
 85                 INIT_LIST_HEAD(&tree->same_root);
 86                 tree->root = NULL;
 87                 strcpy(tree->pathname, s);
 88         }
 89         return tree;
 90 }
 91 
 92 static inline void get_tree(struct audit_tree *tree)
 93 {
 94         atomic_inc(&tree->count);
 95 }
 96 
 97 static inline void put_tree(struct audit_tree *tree)
 98 {
 99         if (atomic_dec_and_test(&tree->count))
100                 kfree_rcu(tree, head);
101 }
102 
103 /* to avoid bringing the entire thing in audit.h */
104 const char *audit_tree_path(struct audit_tree *tree)
105 {
106         return tree->pathname;
107 }
108 
109 static void free_chunk(struct audit_chunk *chunk)
110 {
111         int i;
112 
113         for (i = 0; i < chunk->count; i++) {
114                 if (chunk->owners[i].owner)
115                         put_tree(chunk->owners[i].owner);
116         }
117         kfree(chunk);
118 }
119 
120 void audit_put_chunk(struct audit_chunk *chunk)
121 {
122         if (atomic_long_dec_and_test(&chunk->refs))
123                 free_chunk(chunk);
124 }
125 
126 static void __put_chunk(struct rcu_head *rcu)
127 {
128         struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
129         audit_put_chunk(chunk);
130 }
131 
132 static void audit_tree_destroy_watch(struct fsnotify_mark *entry)
133 {
134         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
135         call_rcu(&chunk->head, __put_chunk);
136 }
137 
138 static struct audit_chunk *alloc_chunk(int count)
139 {
140         struct audit_chunk *chunk;
141         size_t size;
142         int i;
143 
144         size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
145         chunk = kzalloc(size, GFP_KERNEL);
146         if (!chunk)
147                 return NULL;
148 
149         INIT_LIST_HEAD(&chunk->hash);
150         INIT_LIST_HEAD(&chunk->trees);
151         chunk->count = count;
152         atomic_long_set(&chunk->refs, 1);
153         for (i = 0; i < count; i++) {
154                 INIT_LIST_HEAD(&chunk->owners[i].list);
155                 chunk->owners[i].index = i;
156         }
157         fsnotify_init_mark(&chunk->mark, audit_tree_destroy_watch);
158         chunk->mark.mask = FS_IN_IGNORED;
159         return chunk;
160 }
161 
162 enum {HASH_SIZE = 128};
163 static struct list_head chunk_hash_heads[HASH_SIZE];
164 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
165 
166 static inline struct list_head *chunk_hash(const struct inode *inode)
167 {
168         unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
169         return chunk_hash_heads + n % HASH_SIZE;
170 }
171 
172 /* hash_lock & entry->lock is held by caller */
173 static void insert_hash(struct audit_chunk *chunk)
174 {
175         struct fsnotify_mark *entry = &chunk->mark;
176         struct list_head *list;
177 
178         if (!entry->inode)
179                 return;
180         list = chunk_hash(entry->inode);
181         list_add_rcu(&chunk->hash, list);
182 }
183 
184 /* called under rcu_read_lock */
185 struct audit_chunk *audit_tree_lookup(const struct inode *inode)
186 {
187         struct list_head *list = chunk_hash(inode);
188         struct audit_chunk *p;
189 
190         list_for_each_entry_rcu(p, list, hash) {
191                 /* mark.inode may have gone NULL, but who cares? */
192                 if (p->mark.inode == inode) {
193                         atomic_long_inc(&p->refs);
194                         return p;
195                 }
196         }
197         return NULL;
198 }
199 
200 bool audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
201 {
202         int n;
203         for (n = 0; n < chunk->count; n++)
204                 if (chunk->owners[n].owner == tree)
205                         return true;
206         return false;
207 }
208 
209 /* tagging and untagging inodes with trees */
210 
211 static struct audit_chunk *find_chunk(struct node *p)
212 {
213         int index = p->index & ~(1U<<31);
214         p -= index;
215         return container_of(p, struct audit_chunk, owners[0]);
216 }
217 
218 static void untag_chunk(struct node *p)
219 {
220         struct audit_chunk *chunk = find_chunk(p);
221         struct fsnotify_mark *entry = &chunk->mark;
222         struct audit_chunk *new = NULL;
223         struct audit_tree *owner;
224         int size = chunk->count - 1;
225         int i, j;
226 
227         fsnotify_get_mark(entry);
228 
229         spin_unlock(&hash_lock);
230 
231         if (size)
232                 new = alloc_chunk(size);
233 
234         mutex_lock(&entry->group->mark_mutex);
235         spin_lock(&entry->lock);
236         if (chunk->dead || !entry->inode) {
237                 spin_unlock(&entry->lock);
238                 mutex_unlock(&entry->group->mark_mutex);
239                 if (new)
240                         free_chunk(new);
241                 goto out;
242         }
243 
244         owner = p->owner;
245 
246         if (!size) {
247                 chunk->dead = 1;
248                 spin_lock(&hash_lock);
249                 list_del_init(&chunk->trees);
250                 if (owner->root == chunk)
251                         owner->root = NULL;
252                 list_del_init(&p->list);
253                 list_del_rcu(&chunk->hash);
254                 spin_unlock(&hash_lock);
255                 spin_unlock(&entry->lock);
256                 mutex_unlock(&entry->group->mark_mutex);
257                 fsnotify_destroy_mark(entry, audit_tree_group);
258                 goto out;
259         }
260 
261         if (!new)
262                 goto Fallback;
263 
264         if (fsnotify_add_mark_locked(&new->mark, entry->group, entry->inode,
265                                      NULL, 1)) {
266                 fsnotify_put_mark(&new->mark);
267                 goto Fallback;
268         }
269 
270         chunk->dead = 1;
271         spin_lock(&hash_lock);
272         list_replace_init(&chunk->trees, &new->trees);
273         if (owner->root == chunk) {
274                 list_del_init(&owner->same_root);
275                 owner->root = NULL;
276         }
277 
278         for (i = j = 0; j <= size; i++, j++) {
279                 struct audit_tree *s;
280                 if (&chunk->owners[j] == p) {
281                         list_del_init(&p->list);
282                         i--;
283                         continue;
284                 }
285                 s = chunk->owners[j].owner;
286                 new->owners[i].owner = s;
287                 new->owners[i].index = chunk->owners[j].index - j + i;
288                 if (!s) /* result of earlier fallback */
289                         continue;
290                 get_tree(s);
291                 list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
292         }
293 
294         list_replace_rcu(&chunk->hash, &new->hash);
295         list_for_each_entry(owner, &new->trees, same_root)
296                 owner->root = new;
297         spin_unlock(&hash_lock);
298         spin_unlock(&entry->lock);
299         mutex_unlock(&entry->group->mark_mutex);
300         fsnotify_destroy_mark(entry, audit_tree_group);
301         fsnotify_put_mark(&new->mark);  /* drop initial reference */
302         goto out;
303 
304 Fallback:
305         // do the best we can
306         spin_lock(&hash_lock);
307         if (owner->root == chunk) {
308                 list_del_init(&owner->same_root);
309                 owner->root = NULL;
310         }
311         list_del_init(&p->list);
312         p->owner = NULL;
313         put_tree(owner);
314         spin_unlock(&hash_lock);
315         spin_unlock(&entry->lock);
316         mutex_unlock(&entry->group->mark_mutex);
317 out:
318         fsnotify_put_mark(entry);
319         spin_lock(&hash_lock);
320 }
321 
322 static int create_chunk(struct inode *inode, struct audit_tree *tree)
323 {
324         struct fsnotify_mark *entry;
325         struct audit_chunk *chunk = alloc_chunk(1);
326         if (!chunk)
327                 return -ENOMEM;
328 
329         entry = &chunk->mark;
330         if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) {
331                 fsnotify_put_mark(entry);
332                 return -ENOSPC;
333         }
334 
335         spin_lock(&entry->lock);
336         spin_lock(&hash_lock);
337         if (tree->goner) {
338                 spin_unlock(&hash_lock);
339                 chunk->dead = 1;
340                 spin_unlock(&entry->lock);
341                 fsnotify_destroy_mark(entry, audit_tree_group);
342                 fsnotify_put_mark(entry);
343                 return 0;
344         }
345         chunk->owners[0].index = (1U << 31);
346         chunk->owners[0].owner = tree;
347         get_tree(tree);
348         list_add(&chunk->owners[0].list, &tree->chunks);
349         if (!tree->root) {
350                 tree->root = chunk;
351                 list_add(&tree->same_root, &chunk->trees);
352         }
353         insert_hash(chunk);
354         spin_unlock(&hash_lock);
355         spin_unlock(&entry->lock);
356         fsnotify_put_mark(entry);       /* drop initial reference */
357         return 0;
358 }
359 
360 /* the first tagged inode becomes root of tree */
361 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
362 {
363         struct fsnotify_mark *old_entry, *chunk_entry;
364         struct audit_tree *owner;
365         struct audit_chunk *chunk, *old;
366         struct node *p;
367         int n;
368 
369         old_entry = fsnotify_find_inode_mark(audit_tree_group, inode);
370         if (!old_entry)
371                 return create_chunk(inode, tree);
372 
373         old = container_of(old_entry, struct audit_chunk, mark);
374 
375         /* are we already there? */
376         spin_lock(&hash_lock);
377         for (n = 0; n < old->count; n++) {
378                 if (old->owners[n].owner == tree) {
379                         spin_unlock(&hash_lock);
380                         fsnotify_put_mark(old_entry);
381                         return 0;
382                 }
383         }
384         spin_unlock(&hash_lock);
385 
386         chunk = alloc_chunk(old->count + 1);
387         if (!chunk) {
388                 fsnotify_put_mark(old_entry);
389                 return -ENOMEM;
390         }
391 
392         chunk_entry = &chunk->mark;
393 
394         mutex_lock(&old_entry->group->mark_mutex);
395         spin_lock(&old_entry->lock);
396         if (!old_entry->inode) {
397                 /* old_entry is being shot, lets just lie */
398                 spin_unlock(&old_entry->lock);
399                 mutex_unlock(&old_entry->group->mark_mutex);
400                 fsnotify_put_mark(old_entry);
401                 free_chunk(chunk);
402                 return -ENOENT;
403         }
404 
405         if (fsnotify_add_mark_locked(chunk_entry, old_entry->group,
406                                      old_entry->inode, NULL, 1)) {
407                 spin_unlock(&old_entry->lock);
408                 mutex_unlock(&old_entry->group->mark_mutex);
409                 fsnotify_put_mark(chunk_entry);
410                 fsnotify_put_mark(old_entry);
411                 return -ENOSPC;
412         }
413 
414         /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
415         spin_lock(&chunk_entry->lock);
416         spin_lock(&hash_lock);
417 
418         /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
419         if (tree->goner) {
420                 spin_unlock(&hash_lock);
421                 chunk->dead = 1;
422                 spin_unlock(&chunk_entry->lock);
423                 spin_unlock(&old_entry->lock);
424                 mutex_unlock(&old_entry->group->mark_mutex);
425 
426                 fsnotify_destroy_mark(chunk_entry, audit_tree_group);
427 
428                 fsnotify_put_mark(chunk_entry);
429                 fsnotify_put_mark(old_entry);
430                 return 0;
431         }
432         list_replace_init(&old->trees, &chunk->trees);
433         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
434                 struct audit_tree *s = old->owners[n].owner;
435                 p->owner = s;
436                 p->index = old->owners[n].index;
437                 if (!s) /* result of fallback in untag */
438                         continue;
439                 get_tree(s);
440                 list_replace_init(&old->owners[n].list, &p->list);
441         }
442         p->index = (chunk->count - 1) | (1U<<31);
443         p->owner = tree;
444         get_tree(tree);
445         list_add(&p->list, &tree->chunks);
446         list_replace_rcu(&old->hash, &chunk->hash);
447         list_for_each_entry(owner, &chunk->trees, same_root)
448                 owner->root = chunk;
449         old->dead = 1;
450         if (!tree->root) {
451                 tree->root = chunk;
452                 list_add(&tree->same_root, &chunk->trees);
453         }
454         spin_unlock(&hash_lock);
455         spin_unlock(&chunk_entry->lock);
456         spin_unlock(&old_entry->lock);
457         mutex_unlock(&old_entry->group->mark_mutex);
458         fsnotify_destroy_mark(old_entry, audit_tree_group);
459         fsnotify_put_mark(chunk_entry); /* drop initial reference */
460         fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
461         return 0;
462 }
463 
464 static void audit_tree_log_remove_rule(struct audit_krule *rule)
465 {
466         struct audit_buffer *ab;
467 
468         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
469         if (unlikely(!ab))
470                 return;
471         audit_log_format(ab, "op=remove_rule");
472         audit_log_format(ab, " dir=");
473         audit_log_untrustedstring(ab, rule->tree->pathname);
474         audit_log_key(ab, rule->filterkey);
475         audit_log_format(ab, " list=%d res=1", rule->listnr);
476         audit_log_end(ab);
477 }
478 
479 static void kill_rules(struct audit_tree *tree)
480 {
481         struct audit_krule *rule, *next;
482         struct audit_entry *entry;
483 
484         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
485                 entry = container_of(rule, struct audit_entry, rule);
486 
487                 list_del_init(&rule->rlist);
488                 if (rule->tree) {
489                         /* not a half-baked one */
490                         audit_tree_log_remove_rule(rule);
491                         if (entry->rule.exe)
492                                 audit_remove_mark(entry->rule.exe);
493                         rule->tree = NULL;
494                         list_del_rcu(&entry->list);
495                         list_del(&entry->rule.list);
496                         call_rcu(&entry->rcu, audit_free_rule_rcu);
497                 }
498         }
499 }
500 
501 /*
502  * finish killing struct audit_tree
503  */
504 static void prune_one(struct audit_tree *victim)
505 {
506         spin_lock(&hash_lock);
507         while (!list_empty(&victim->chunks)) {
508                 struct node *p;
509 
510                 p = list_entry(victim->chunks.next, struct node, list);
511 
512                 untag_chunk(p);
513         }
514         spin_unlock(&hash_lock);
515         put_tree(victim);
516 }
517 
518 /* trim the uncommitted chunks from tree */
519 
520 static void trim_marked(struct audit_tree *tree)
521 {
522         struct list_head *p, *q;
523         spin_lock(&hash_lock);
524         if (tree->goner) {
525                 spin_unlock(&hash_lock);
526                 return;
527         }
528         /* reorder */
529         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
530                 struct node *node = list_entry(p, struct node, list);
531                 q = p->next;
532                 if (node->index & (1U<<31)) {
533                         list_del_init(p);
534                         list_add(p, &tree->chunks);
535                 }
536         }
537 
538         while (!list_empty(&tree->chunks)) {
539                 struct node *node;
540 
541                 node = list_entry(tree->chunks.next, struct node, list);
542 
543                 /* have we run out of marked? */
544                 if (!(node->index & (1U<<31)))
545                         break;
546 
547                 untag_chunk(node);
548         }
549         if (!tree->root && !tree->goner) {
550                 tree->goner = 1;
551                 spin_unlock(&hash_lock);
552                 mutex_lock(&audit_filter_mutex);
553                 kill_rules(tree);
554                 list_del_init(&tree->list);
555                 mutex_unlock(&audit_filter_mutex);
556                 prune_one(tree);
557         } else {
558                 spin_unlock(&hash_lock);
559         }
560 }
561 
562 static void audit_schedule_prune(void);
563 
564 /* called with audit_filter_mutex */
565 int audit_remove_tree_rule(struct audit_krule *rule)
566 {
567         struct audit_tree *tree;
568         tree = rule->tree;
569         if (tree) {
570                 spin_lock(&hash_lock);
571                 list_del_init(&rule->rlist);
572                 if (list_empty(&tree->rules) && !tree->goner) {
573                         tree->root = NULL;
574                         list_del_init(&tree->same_root);
575                         tree->goner = 1;
576                         list_move(&tree->list, &prune_list);
577                         rule->tree = NULL;
578                         spin_unlock(&hash_lock);
579                         audit_schedule_prune();
580                         return 1;
581                 }
582                 rule->tree = NULL;
583                 spin_unlock(&hash_lock);
584                 return 1;
585         }
586         return 0;
587 }
588 
589 static int compare_root(struct vfsmount *mnt, void *arg)
590 {
591         return d_backing_inode(mnt->mnt_root) == arg;
592 }
593 
594 void audit_trim_trees(void)
595 {
596         struct list_head cursor;
597 
598         mutex_lock(&audit_filter_mutex);
599         list_add(&cursor, &tree_list);
600         while (cursor.next != &tree_list) {
601                 struct audit_tree *tree;
602                 struct path path;
603                 struct vfsmount *root_mnt;
604                 struct node *node;
605                 int err;
606 
607                 tree = container_of(cursor.next, struct audit_tree, list);
608                 get_tree(tree);
609                 list_del(&cursor);
610                 list_add(&cursor, &tree->list);
611                 mutex_unlock(&audit_filter_mutex);
612 
613                 err = kern_path(tree->pathname, 0, &path);
614                 if (err)
615                         goto skip_it;
616 
617                 root_mnt = collect_mounts(&path);
618                 path_put(&path);
619                 if (IS_ERR(root_mnt))
620                         goto skip_it;
621 
622                 spin_lock(&hash_lock);
623                 list_for_each_entry(node, &tree->chunks, list) {
624                         struct audit_chunk *chunk = find_chunk(node);
625                         /* this could be NULL if the watch is dying else where... */
626                         struct inode *inode = chunk->mark.inode;
627                         node->index |= 1U<<31;
628                         if (iterate_mounts(compare_root, inode, root_mnt))
629                                 node->index &= ~(1U<<31);
630                 }
631                 spin_unlock(&hash_lock);
632                 trim_marked(tree);
633                 drop_collected_mounts(root_mnt);
634 skip_it:
635                 put_tree(tree);
636                 mutex_lock(&audit_filter_mutex);
637         }
638         list_del(&cursor);
639         mutex_unlock(&audit_filter_mutex);
640 }
641 
642 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
643 {
644 
645         if (pathname[0] != '/' ||
646             rule->listnr != AUDIT_FILTER_EXIT ||
647             op != Audit_equal ||
648             rule->inode_f || rule->watch || rule->tree)
649                 return -EINVAL;
650         rule->tree = alloc_tree(pathname);
651         if (!rule->tree)
652                 return -ENOMEM;
653         return 0;
654 }
655 
656 void audit_put_tree(struct audit_tree *tree)
657 {
658         put_tree(tree);
659 }
660 
661 static int tag_mount(struct vfsmount *mnt, void *arg)
662 {
663         return tag_chunk(d_backing_inode(mnt->mnt_root), arg);
664 }
665 
666 /*
667  * That gets run when evict_chunk() ends up needing to kill audit_tree.
668  * Runs from a separate thread.
669  */
670 static int prune_tree_thread(void *unused)
671 {
672         for (;;) {
673                 if (list_empty(&prune_list)) {
674                         set_current_state(TASK_INTERRUPTIBLE);
675                         schedule();
676                 }
677 
678                 mutex_lock(&audit_cmd_mutex);
679                 mutex_lock(&audit_filter_mutex);
680 
681                 while (!list_empty(&prune_list)) {
682                         struct audit_tree *victim;
683 
684                         victim = list_entry(prune_list.next,
685                                         struct audit_tree, list);
686                         list_del_init(&victim->list);
687 
688                         mutex_unlock(&audit_filter_mutex);
689 
690                         prune_one(victim);
691 
692                         mutex_lock(&audit_filter_mutex);
693                 }
694 
695                 mutex_unlock(&audit_filter_mutex);
696                 mutex_unlock(&audit_cmd_mutex);
697         }
698         return 0;
699 }
700 
701 static int audit_launch_prune(void)
702 {
703         if (prune_thread)
704                 return 0;
705         prune_thread = kthread_run(prune_tree_thread, NULL,
706                                 "audit_prune_tree");
707         if (IS_ERR(prune_thread)) {
708                 pr_err("cannot start thread audit_prune_tree");
709                 prune_thread = NULL;
710                 return -ENOMEM;
711         }
712         return 0;
713 }
714 
715 /* called with audit_filter_mutex */
716 int audit_add_tree_rule(struct audit_krule *rule)
717 {
718         struct audit_tree *seed = rule->tree, *tree;
719         struct path path;
720         struct vfsmount *mnt;
721         int err;
722 
723         rule->tree = NULL;
724         list_for_each_entry(tree, &tree_list, list) {
725                 if (!strcmp(seed->pathname, tree->pathname)) {
726                         put_tree(seed);
727                         rule->tree = tree;
728                         list_add(&rule->rlist, &tree->rules);
729                         return 0;
730                 }
731         }
732         tree = seed;
733         list_add(&tree->list, &tree_list);
734         list_add(&rule->rlist, &tree->rules);
735         /* do not set rule->tree yet */
736         mutex_unlock(&audit_filter_mutex);
737 
738         if (unlikely(!prune_thread)) {
739                 err = audit_launch_prune();
740                 if (err)
741                         goto Err;
742         }
743 
744         err = kern_path(tree->pathname, 0, &path);
745         if (err)
746                 goto Err;
747         mnt = collect_mounts(&path);
748         path_put(&path);
749         if (IS_ERR(mnt)) {
750                 err = PTR_ERR(mnt);
751                 goto Err;
752         }
753 
754         get_tree(tree);
755         err = iterate_mounts(tag_mount, tree, mnt);
756         drop_collected_mounts(mnt);
757 
758         if (!err) {
759                 struct node *node;
760                 spin_lock(&hash_lock);
761                 list_for_each_entry(node, &tree->chunks, list)
762                         node->index &= ~(1U<<31);
763                 spin_unlock(&hash_lock);
764         } else {
765                 trim_marked(tree);
766                 goto Err;
767         }
768 
769         mutex_lock(&audit_filter_mutex);
770         if (list_empty(&rule->rlist)) {
771                 put_tree(tree);
772                 return -ENOENT;
773         }
774         rule->tree = tree;
775         put_tree(tree);
776 
777         return 0;
778 Err:
779         mutex_lock(&audit_filter_mutex);
780         list_del_init(&tree->list);
781         list_del_init(&tree->rules);
782         put_tree(tree);
783         return err;
784 }
785 
786 int audit_tag_tree(char *old, char *new)
787 {
788         struct list_head cursor, barrier;
789         int failed = 0;
790         struct path path1, path2;
791         struct vfsmount *tagged;
792         int err;
793 
794         err = kern_path(new, 0, &path2);
795         if (err)
796                 return err;
797         tagged = collect_mounts(&path2);
798         path_put(&path2);
799         if (IS_ERR(tagged))
800                 return PTR_ERR(tagged);
801 
802         err = kern_path(old, 0, &path1);
803         if (err) {
804                 drop_collected_mounts(tagged);
805                 return err;
806         }
807 
808         mutex_lock(&audit_filter_mutex);
809         list_add(&barrier, &tree_list);
810         list_add(&cursor, &barrier);
811 
812         while (cursor.next != &tree_list) {
813                 struct audit_tree *tree;
814                 int good_one = 0;
815 
816                 tree = container_of(cursor.next, struct audit_tree, list);
817                 get_tree(tree);
818                 list_del(&cursor);
819                 list_add(&cursor, &tree->list);
820                 mutex_unlock(&audit_filter_mutex);
821 
822                 err = kern_path(tree->pathname, 0, &path2);
823                 if (!err) {
824                         good_one = path_is_under(&path1, &path2);
825                         path_put(&path2);
826                 }
827 
828                 if (!good_one) {
829                         put_tree(tree);
830                         mutex_lock(&audit_filter_mutex);
831                         continue;
832                 }
833 
834                 failed = iterate_mounts(tag_mount, tree, tagged);
835                 if (failed) {
836                         put_tree(tree);
837                         mutex_lock(&audit_filter_mutex);
838                         break;
839                 }
840 
841                 mutex_lock(&audit_filter_mutex);
842                 spin_lock(&hash_lock);
843                 if (!tree->goner) {
844                         list_del(&tree->list);
845                         list_add(&tree->list, &tree_list);
846                 }
847                 spin_unlock(&hash_lock);
848                 put_tree(tree);
849         }
850 
851         while (barrier.prev != &tree_list) {
852                 struct audit_tree *tree;
853 
854                 tree = container_of(barrier.prev, struct audit_tree, list);
855                 get_tree(tree);
856                 list_del(&tree->list);
857                 list_add(&tree->list, &barrier);
858                 mutex_unlock(&audit_filter_mutex);
859 
860                 if (!failed) {
861                         struct node *node;
862                         spin_lock(&hash_lock);
863                         list_for_each_entry(node, &tree->chunks, list)
864                                 node->index &= ~(1U<<31);
865                         spin_unlock(&hash_lock);
866                 } else {
867                         trim_marked(tree);
868                 }
869 
870                 put_tree(tree);
871                 mutex_lock(&audit_filter_mutex);
872         }
873         list_del(&barrier);
874         list_del(&cursor);
875         mutex_unlock(&audit_filter_mutex);
876         path_put(&path1);
877         drop_collected_mounts(tagged);
878         return failed;
879 }
880 
881 
882 static void audit_schedule_prune(void)
883 {
884         wake_up_process(prune_thread);
885 }
886 
887 /*
888  * ... and that one is done if evict_chunk() decides to delay until the end
889  * of syscall.  Runs synchronously.
890  */
891 void audit_kill_trees(struct list_head *list)
892 {
893         mutex_lock(&audit_cmd_mutex);
894         mutex_lock(&audit_filter_mutex);
895 
896         while (!list_empty(list)) {
897                 struct audit_tree *victim;
898 
899                 victim = list_entry(list->next, struct audit_tree, list);
900                 kill_rules(victim);
901                 list_del_init(&victim->list);
902 
903                 mutex_unlock(&audit_filter_mutex);
904 
905                 prune_one(victim);
906 
907                 mutex_lock(&audit_filter_mutex);
908         }
909 
910         mutex_unlock(&audit_filter_mutex);
911         mutex_unlock(&audit_cmd_mutex);
912 }
913 
914 /*
915  *  Here comes the stuff asynchronous to auditctl operations
916  */
917 
918 static void evict_chunk(struct audit_chunk *chunk)
919 {
920         struct audit_tree *owner;
921         struct list_head *postponed = audit_killed_trees();
922         int need_prune = 0;
923         int n;
924 
925         if (chunk->dead)
926                 return;
927 
928         chunk->dead = 1;
929         mutex_lock(&audit_filter_mutex);
930         spin_lock(&hash_lock);
931         while (!list_empty(&chunk->trees)) {
932                 owner = list_entry(chunk->trees.next,
933                                    struct audit_tree, same_root);
934                 owner->goner = 1;
935                 owner->root = NULL;
936                 list_del_init(&owner->same_root);
937                 spin_unlock(&hash_lock);
938                 if (!postponed) {
939                         kill_rules(owner);
940                         list_move(&owner->list, &prune_list);
941                         need_prune = 1;
942                 } else {
943                         list_move(&owner->list, postponed);
944                 }
945                 spin_lock(&hash_lock);
946         }
947         list_del_rcu(&chunk->hash);
948         for (n = 0; n < chunk->count; n++)
949                 list_del_init(&chunk->owners[n].list);
950         spin_unlock(&hash_lock);
951         mutex_unlock(&audit_filter_mutex);
952         if (need_prune)
953                 audit_schedule_prune();
954 }
955 
956 static int audit_tree_handle_event(struct fsnotify_group *group,
957                                    struct inode *to_tell,
958                                    struct fsnotify_mark *inode_mark,
959                                    struct fsnotify_mark *vfsmount_mark,
960                                    u32 mask, const void *data, int data_type,
961                                    const unsigned char *file_name, u32 cookie)
962 {
963         return 0;
964 }
965 
966 static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
967 {
968         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
969 
970         evict_chunk(chunk);
971 
972         /*
973          * We are guaranteed to have at least one reference to the mark from
974          * either the inode or the caller of fsnotify_destroy_mark().
975          */
976         BUG_ON(atomic_read(&entry->refcnt) < 1);
977 }
978 
979 static const struct fsnotify_ops audit_tree_ops = {
980         .handle_event = audit_tree_handle_event,
981         .freeing_mark = audit_tree_freeing_mark,
982 };
983 
984 static int __init audit_tree_init(void)
985 {
986         int i;
987 
988         audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
989         if (IS_ERR(audit_tree_group))
990                 audit_panic("cannot initialize fsnotify group for rectree watches");
991 
992         for (i = 0; i < HASH_SIZE; i++)
993                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
994 
995         return 0;
996 }
997 __initcall(audit_tree_init);
998 

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