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TOMOYO Linux Cross Reference
Linux/kernel/audit_tree.c

Version: ~ [ linux-5.4-rc3 ] ~ [ linux-5.3.6 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.79 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.149 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.196 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.196 ] ~ [ 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-3.16.75 ] ~ [ 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-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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         spin_lock(&entry->lock);
235         if (chunk->dead || !entry->inode) {
236                 spin_unlock(&entry->lock);
237                 if (new)
238                         free_chunk(new);
239                 goto out;
240         }
241 
242         owner = p->owner;
243 
244         if (!size) {
245                 chunk->dead = 1;
246                 spin_lock(&hash_lock);
247                 list_del_init(&chunk->trees);
248                 if (owner->root == chunk)
249                         owner->root = NULL;
250                 list_del_init(&p->list);
251                 list_del_rcu(&chunk->hash);
252                 spin_unlock(&hash_lock);
253                 spin_unlock(&entry->lock);
254                 fsnotify_destroy_mark(entry, audit_tree_group);
255                 goto out;
256         }
257 
258         if (!new)
259                 goto Fallback;
260 
261         fsnotify_duplicate_mark(&new->mark, entry);
262         if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.inode, NULL, 1)) {
263                 fsnotify_put_mark(&new->mark);
264                 goto Fallback;
265         }
266 
267         chunk->dead = 1;
268         spin_lock(&hash_lock);
269         list_replace_init(&chunk->trees, &new->trees);
270         if (owner->root == chunk) {
271                 list_del_init(&owner->same_root);
272                 owner->root = NULL;
273         }
274 
275         for (i = j = 0; j <= size; i++, j++) {
276                 struct audit_tree *s;
277                 if (&chunk->owners[j] == p) {
278                         list_del_init(&p->list);
279                         i--;
280                         continue;
281                 }
282                 s = chunk->owners[j].owner;
283                 new->owners[i].owner = s;
284                 new->owners[i].index = chunk->owners[j].index - j + i;
285                 if (!s) /* result of earlier fallback */
286                         continue;
287                 get_tree(s);
288                 list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
289         }
290 
291         list_replace_rcu(&chunk->hash, &new->hash);
292         list_for_each_entry(owner, &new->trees, same_root)
293                 owner->root = new;
294         spin_unlock(&hash_lock);
295         spin_unlock(&entry->lock);
296         fsnotify_destroy_mark(entry, audit_tree_group);
297         fsnotify_put_mark(&new->mark);  /* drop initial reference */
298         goto out;
299 
300 Fallback:
301         // do the best we can
302         spin_lock(&hash_lock);
303         if (owner->root == chunk) {
304                 list_del_init(&owner->same_root);
305                 owner->root = NULL;
306         }
307         list_del_init(&p->list);
308         p->owner = NULL;
309         put_tree(owner);
310         spin_unlock(&hash_lock);
311         spin_unlock(&entry->lock);
312 out:
313         fsnotify_put_mark(entry);
314         spin_lock(&hash_lock);
315 }
316 
317 static int create_chunk(struct inode *inode, struct audit_tree *tree)
318 {
319         struct fsnotify_mark *entry;
320         struct audit_chunk *chunk = alloc_chunk(1);
321         if (!chunk)
322                 return -ENOMEM;
323 
324         entry = &chunk->mark;
325         if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) {
326                 fsnotify_put_mark(entry);
327                 return -ENOSPC;
328         }
329 
330         spin_lock(&entry->lock);
331         spin_lock(&hash_lock);
332         if (tree->goner) {
333                 spin_unlock(&hash_lock);
334                 chunk->dead = 1;
335                 spin_unlock(&entry->lock);
336                 fsnotify_destroy_mark(entry, audit_tree_group);
337                 fsnotify_put_mark(entry);
338                 return 0;
339         }
340         chunk->owners[0].index = (1U << 31);
341         chunk->owners[0].owner = tree;
342         get_tree(tree);
343         list_add(&chunk->owners[0].list, &tree->chunks);
344         if (!tree->root) {
345                 tree->root = chunk;
346                 list_add(&tree->same_root, &chunk->trees);
347         }
348         insert_hash(chunk);
349         spin_unlock(&hash_lock);
350         spin_unlock(&entry->lock);
351         fsnotify_put_mark(entry);       /* drop initial reference */
352         return 0;
353 }
354 
355 /* the first tagged inode becomes root of tree */
356 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
357 {
358         struct fsnotify_mark *old_entry, *chunk_entry;
359         struct audit_tree *owner;
360         struct audit_chunk *chunk, *old;
361         struct node *p;
362         int n;
363 
364         old_entry = fsnotify_find_inode_mark(audit_tree_group, inode);
365         if (!old_entry)
366                 return create_chunk(inode, tree);
367 
368         old = container_of(old_entry, struct audit_chunk, mark);
369 
370         /* are we already there? */
371         spin_lock(&hash_lock);
372         for (n = 0; n < old->count; n++) {
373                 if (old->owners[n].owner == tree) {
374                         spin_unlock(&hash_lock);
375                         fsnotify_put_mark(old_entry);
376                         return 0;
377                 }
378         }
379         spin_unlock(&hash_lock);
380 
381         chunk = alloc_chunk(old->count + 1);
382         if (!chunk) {
383                 fsnotify_put_mark(old_entry);
384                 return -ENOMEM;
385         }
386 
387         chunk_entry = &chunk->mark;
388 
389         spin_lock(&old_entry->lock);
390         if (!old_entry->inode) {
391                 /* old_entry is being shot, lets just lie */
392                 spin_unlock(&old_entry->lock);
393                 fsnotify_put_mark(old_entry);
394                 free_chunk(chunk);
395                 return -ENOENT;
396         }
397 
398         fsnotify_duplicate_mark(chunk_entry, old_entry);
399         if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->inode, NULL, 1)) {
400                 spin_unlock(&old_entry->lock);
401                 fsnotify_put_mark(chunk_entry);
402                 fsnotify_put_mark(old_entry);
403                 return -ENOSPC;
404         }
405 
406         /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
407         spin_lock(&chunk_entry->lock);
408         spin_lock(&hash_lock);
409 
410         /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
411         if (tree->goner) {
412                 spin_unlock(&hash_lock);
413                 chunk->dead = 1;
414                 spin_unlock(&chunk_entry->lock);
415                 spin_unlock(&old_entry->lock);
416 
417                 fsnotify_destroy_mark(chunk_entry, audit_tree_group);
418 
419                 fsnotify_put_mark(chunk_entry);
420                 fsnotify_put_mark(old_entry);
421                 return 0;
422         }
423         list_replace_init(&old->trees, &chunk->trees);
424         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
425                 struct audit_tree *s = old->owners[n].owner;
426                 p->owner = s;
427                 p->index = old->owners[n].index;
428                 if (!s) /* result of fallback in untag */
429                         continue;
430                 get_tree(s);
431                 list_replace_init(&old->owners[n].list, &p->list);
432         }
433         p->index = (chunk->count - 1) | (1U<<31);
434         p->owner = tree;
435         get_tree(tree);
436         list_add(&p->list, &tree->chunks);
437         list_replace_rcu(&old->hash, &chunk->hash);
438         list_for_each_entry(owner, &chunk->trees, same_root)
439                 owner->root = chunk;
440         old->dead = 1;
441         if (!tree->root) {
442                 tree->root = chunk;
443                 list_add(&tree->same_root, &chunk->trees);
444         }
445         spin_unlock(&hash_lock);
446         spin_unlock(&chunk_entry->lock);
447         spin_unlock(&old_entry->lock);
448         fsnotify_destroy_mark(old_entry, audit_tree_group);
449         fsnotify_put_mark(chunk_entry); /* drop initial reference */
450         fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
451         return 0;
452 }
453 
454 static void audit_tree_log_remove_rule(struct audit_krule *rule)
455 {
456         struct audit_buffer *ab;
457 
458         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
459         if (unlikely(!ab))
460                 return;
461         audit_log_format(ab, "op=");
462         audit_log_string(ab, "remove_rule");
463         audit_log_format(ab, " dir=");
464         audit_log_untrustedstring(ab, rule->tree->pathname);
465         audit_log_key(ab, rule->filterkey);
466         audit_log_format(ab, " list=%d res=1", rule->listnr);
467         audit_log_end(ab);
468 }
469 
470 static void kill_rules(struct audit_tree *tree)
471 {
472         struct audit_krule *rule, *next;
473         struct audit_entry *entry;
474 
475         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
476                 entry = container_of(rule, struct audit_entry, rule);
477 
478                 list_del_init(&rule->rlist);
479                 if (rule->tree) {
480                         /* not a half-baked one */
481                         audit_tree_log_remove_rule(rule);
482                         if (entry->rule.exe)
483                                 audit_remove_mark(entry->rule.exe);
484                         rule->tree = NULL;
485                         list_del_rcu(&entry->list);
486                         list_del(&entry->rule.list);
487                         call_rcu(&entry->rcu, audit_free_rule_rcu);
488                 }
489         }
490 }
491 
492 /*
493  * finish killing struct audit_tree
494  */
495 static void prune_one(struct audit_tree *victim)
496 {
497         spin_lock(&hash_lock);
498         while (!list_empty(&victim->chunks)) {
499                 struct node *p;
500 
501                 p = list_entry(victim->chunks.next, struct node, list);
502 
503                 untag_chunk(p);
504         }
505         spin_unlock(&hash_lock);
506         put_tree(victim);
507 }
508 
509 /* trim the uncommitted chunks from tree */
510 
511 static void trim_marked(struct audit_tree *tree)
512 {
513         struct list_head *p, *q;
514         spin_lock(&hash_lock);
515         if (tree->goner) {
516                 spin_unlock(&hash_lock);
517                 return;
518         }
519         /* reorder */
520         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
521                 struct node *node = list_entry(p, struct node, list);
522                 q = p->next;
523                 if (node->index & (1U<<31)) {
524                         list_del_init(p);
525                         list_add(p, &tree->chunks);
526                 }
527         }
528 
529         while (!list_empty(&tree->chunks)) {
530                 struct node *node;
531 
532                 node = list_entry(tree->chunks.next, struct node, list);
533 
534                 /* have we run out of marked? */
535                 if (!(node->index & (1U<<31)))
536                         break;
537 
538                 untag_chunk(node);
539         }
540         if (!tree->root && !tree->goner) {
541                 tree->goner = 1;
542                 spin_unlock(&hash_lock);
543                 mutex_lock(&audit_filter_mutex);
544                 kill_rules(tree);
545                 list_del_init(&tree->list);
546                 mutex_unlock(&audit_filter_mutex);
547                 prune_one(tree);
548         } else {
549                 spin_unlock(&hash_lock);
550         }
551 }
552 
553 static void audit_schedule_prune(void);
554 
555 /* called with audit_filter_mutex */
556 int audit_remove_tree_rule(struct audit_krule *rule)
557 {
558         struct audit_tree *tree;
559         tree = rule->tree;
560         if (tree) {
561                 spin_lock(&hash_lock);
562                 list_del_init(&rule->rlist);
563                 if (list_empty(&tree->rules) && !tree->goner) {
564                         tree->root = NULL;
565                         list_del_init(&tree->same_root);
566                         tree->goner = 1;
567                         list_move(&tree->list, &prune_list);
568                         rule->tree = NULL;
569                         spin_unlock(&hash_lock);
570                         audit_schedule_prune();
571                         return 1;
572                 }
573                 rule->tree = NULL;
574                 spin_unlock(&hash_lock);
575                 return 1;
576         }
577         return 0;
578 }
579 
580 static int compare_root(struct vfsmount *mnt, void *arg)
581 {
582         return d_backing_inode(mnt->mnt_root) == arg;
583 }
584 
585 void audit_trim_trees(void)
586 {
587         struct list_head cursor;
588 
589         mutex_lock(&audit_filter_mutex);
590         list_add(&cursor, &tree_list);
591         while (cursor.next != &tree_list) {
592                 struct audit_tree *tree;
593                 struct path path;
594                 struct vfsmount *root_mnt;
595                 struct node *node;
596                 int err;
597 
598                 tree = container_of(cursor.next, struct audit_tree, list);
599                 get_tree(tree);
600                 list_del(&cursor);
601                 list_add(&cursor, &tree->list);
602                 mutex_unlock(&audit_filter_mutex);
603 
604                 err = kern_path(tree->pathname, 0, &path);
605                 if (err)
606                         goto skip_it;
607 
608                 root_mnt = collect_mounts(&path);
609                 path_put(&path);
610                 if (IS_ERR(root_mnt))
611                         goto skip_it;
612 
613                 spin_lock(&hash_lock);
614                 list_for_each_entry(node, &tree->chunks, list) {
615                         struct audit_chunk *chunk = find_chunk(node);
616                         /* this could be NULL if the watch is dying else where... */
617                         struct inode *inode = chunk->mark.inode;
618                         node->index |= 1U<<31;
619                         if (iterate_mounts(compare_root, inode, root_mnt))
620                                 node->index &= ~(1U<<31);
621                 }
622                 spin_unlock(&hash_lock);
623                 trim_marked(tree);
624                 drop_collected_mounts(root_mnt);
625 skip_it:
626                 put_tree(tree);
627                 mutex_lock(&audit_filter_mutex);
628         }
629         list_del(&cursor);
630         mutex_unlock(&audit_filter_mutex);
631 }
632 
633 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
634 {
635 
636         if (pathname[0] != '/' ||
637             rule->listnr != AUDIT_FILTER_EXIT ||
638             op != Audit_equal ||
639             rule->inode_f || rule->watch || rule->tree)
640                 return -EINVAL;
641         rule->tree = alloc_tree(pathname);
642         if (!rule->tree)
643                 return -ENOMEM;
644         return 0;
645 }
646 
647 void audit_put_tree(struct audit_tree *tree)
648 {
649         put_tree(tree);
650 }
651 
652 static int tag_mount(struct vfsmount *mnt, void *arg)
653 {
654         return tag_chunk(d_backing_inode(mnt->mnt_root), arg);
655 }
656 
657 /*
658  * That gets run when evict_chunk() ends up needing to kill audit_tree.
659  * Runs from a separate thread.
660  */
661 static int prune_tree_thread(void *unused)
662 {
663         for (;;) {
664                 if (list_empty(&prune_list)) {
665                         set_current_state(TASK_INTERRUPTIBLE);
666                         schedule();
667                 }
668 
669                 mutex_lock(&audit_cmd_mutex);
670                 mutex_lock(&audit_filter_mutex);
671 
672                 while (!list_empty(&prune_list)) {
673                         struct audit_tree *victim;
674 
675                         victim = list_entry(prune_list.next,
676                                         struct audit_tree, list);
677                         list_del_init(&victim->list);
678 
679                         mutex_unlock(&audit_filter_mutex);
680 
681                         prune_one(victim);
682 
683                         mutex_lock(&audit_filter_mutex);
684                 }
685 
686                 mutex_unlock(&audit_filter_mutex);
687                 mutex_unlock(&audit_cmd_mutex);
688         }
689         return 0;
690 }
691 
692 static int audit_launch_prune(void)
693 {
694         if (prune_thread)
695                 return 0;
696         prune_thread = kthread_run(prune_tree_thread, NULL,
697                                 "audit_prune_tree");
698         if (IS_ERR(prune_thread)) {
699                 pr_err("cannot start thread audit_prune_tree");
700                 prune_thread = NULL;
701                 return -ENOMEM;
702         }
703         return 0;
704 }
705 
706 /* called with audit_filter_mutex */
707 int audit_add_tree_rule(struct audit_krule *rule)
708 {
709         struct audit_tree *seed = rule->tree, *tree;
710         struct path path;
711         struct vfsmount *mnt;
712         int err;
713 
714         rule->tree = NULL;
715         list_for_each_entry(tree, &tree_list, list) {
716                 if (!strcmp(seed->pathname, tree->pathname)) {
717                         put_tree(seed);
718                         rule->tree = tree;
719                         list_add(&rule->rlist, &tree->rules);
720                         return 0;
721                 }
722         }
723         tree = seed;
724         list_add(&tree->list, &tree_list);
725         list_add(&rule->rlist, &tree->rules);
726         /* do not set rule->tree yet */
727         mutex_unlock(&audit_filter_mutex);
728 
729         if (unlikely(!prune_thread)) {
730                 err = audit_launch_prune();
731                 if (err)
732                         goto Err;
733         }
734 
735         err = kern_path(tree->pathname, 0, &path);
736         if (err)
737                 goto Err;
738         mnt = collect_mounts(&path);
739         path_put(&path);
740         if (IS_ERR(mnt)) {
741                 err = PTR_ERR(mnt);
742                 goto Err;
743         }
744 
745         get_tree(tree);
746         err = iterate_mounts(tag_mount, tree, mnt);
747         drop_collected_mounts(mnt);
748 
749         if (!err) {
750                 struct node *node;
751                 spin_lock(&hash_lock);
752                 list_for_each_entry(node, &tree->chunks, list)
753                         node->index &= ~(1U<<31);
754                 spin_unlock(&hash_lock);
755         } else {
756                 trim_marked(tree);
757                 goto Err;
758         }
759 
760         mutex_lock(&audit_filter_mutex);
761         if (list_empty(&rule->rlist)) {
762                 put_tree(tree);
763                 return -ENOENT;
764         }
765         rule->tree = tree;
766         put_tree(tree);
767 
768         return 0;
769 Err:
770         mutex_lock(&audit_filter_mutex);
771         list_del_init(&tree->list);
772         list_del_init(&tree->rules);
773         put_tree(tree);
774         return err;
775 }
776 
777 int audit_tag_tree(char *old, char *new)
778 {
779         struct list_head cursor, barrier;
780         int failed = 0;
781         struct path path1, path2;
782         struct vfsmount *tagged;
783         int err;
784 
785         err = kern_path(new, 0, &path2);
786         if (err)
787                 return err;
788         tagged = collect_mounts(&path2);
789         path_put(&path2);
790         if (IS_ERR(tagged))
791                 return PTR_ERR(tagged);
792 
793         err = kern_path(old, 0, &path1);
794         if (err) {
795                 drop_collected_mounts(tagged);
796                 return err;
797         }
798 
799         mutex_lock(&audit_filter_mutex);
800         list_add(&barrier, &tree_list);
801         list_add(&cursor, &barrier);
802 
803         while (cursor.next != &tree_list) {
804                 struct audit_tree *tree;
805                 int good_one = 0;
806 
807                 tree = container_of(cursor.next, struct audit_tree, list);
808                 get_tree(tree);
809                 list_del(&cursor);
810                 list_add(&cursor, &tree->list);
811                 mutex_unlock(&audit_filter_mutex);
812 
813                 err = kern_path(tree->pathname, 0, &path2);
814                 if (!err) {
815                         good_one = path_is_under(&path1, &path2);
816                         path_put(&path2);
817                 }
818 
819                 if (!good_one) {
820                         put_tree(tree);
821                         mutex_lock(&audit_filter_mutex);
822                         continue;
823                 }
824 
825                 failed = iterate_mounts(tag_mount, tree, tagged);
826                 if (failed) {
827                         put_tree(tree);
828                         mutex_lock(&audit_filter_mutex);
829                         break;
830                 }
831 
832                 mutex_lock(&audit_filter_mutex);
833                 spin_lock(&hash_lock);
834                 if (!tree->goner) {
835                         list_del(&tree->list);
836                         list_add(&tree->list, &tree_list);
837                 }
838                 spin_unlock(&hash_lock);
839                 put_tree(tree);
840         }
841 
842         while (barrier.prev != &tree_list) {
843                 struct audit_tree *tree;
844 
845                 tree = container_of(barrier.prev, struct audit_tree, list);
846                 get_tree(tree);
847                 list_del(&tree->list);
848                 list_add(&tree->list, &barrier);
849                 mutex_unlock(&audit_filter_mutex);
850 
851                 if (!failed) {
852                         struct node *node;
853                         spin_lock(&hash_lock);
854                         list_for_each_entry(node, &tree->chunks, list)
855                                 node->index &= ~(1U<<31);
856                         spin_unlock(&hash_lock);
857                 } else {
858                         trim_marked(tree);
859                 }
860 
861                 put_tree(tree);
862                 mutex_lock(&audit_filter_mutex);
863         }
864         list_del(&barrier);
865         list_del(&cursor);
866         mutex_unlock(&audit_filter_mutex);
867         path_put(&path1);
868         drop_collected_mounts(tagged);
869         return failed;
870 }
871 
872 
873 static void audit_schedule_prune(void)
874 {
875         wake_up_process(prune_thread);
876 }
877 
878 /*
879  * ... and that one is done if evict_chunk() decides to delay until the end
880  * of syscall.  Runs synchronously.
881  */
882 void audit_kill_trees(struct list_head *list)
883 {
884         mutex_lock(&audit_cmd_mutex);
885         mutex_lock(&audit_filter_mutex);
886 
887         while (!list_empty(list)) {
888                 struct audit_tree *victim;
889 
890                 victim = list_entry(list->next, struct audit_tree, list);
891                 kill_rules(victim);
892                 list_del_init(&victim->list);
893 
894                 mutex_unlock(&audit_filter_mutex);
895 
896                 prune_one(victim);
897 
898                 mutex_lock(&audit_filter_mutex);
899         }
900 
901         mutex_unlock(&audit_filter_mutex);
902         mutex_unlock(&audit_cmd_mutex);
903 }
904 
905 /*
906  *  Here comes the stuff asynchronous to auditctl operations
907  */
908 
909 static void evict_chunk(struct audit_chunk *chunk)
910 {
911         struct audit_tree *owner;
912         struct list_head *postponed = audit_killed_trees();
913         int need_prune = 0;
914         int n;
915 
916         if (chunk->dead)
917                 return;
918 
919         chunk->dead = 1;
920         mutex_lock(&audit_filter_mutex);
921         spin_lock(&hash_lock);
922         while (!list_empty(&chunk->trees)) {
923                 owner = list_entry(chunk->trees.next,
924                                    struct audit_tree, same_root);
925                 owner->goner = 1;
926                 owner->root = NULL;
927                 list_del_init(&owner->same_root);
928                 spin_unlock(&hash_lock);
929                 if (!postponed) {
930                         kill_rules(owner);
931                         list_move(&owner->list, &prune_list);
932                         need_prune = 1;
933                 } else {
934                         list_move(&owner->list, postponed);
935                 }
936                 spin_lock(&hash_lock);
937         }
938         list_del_rcu(&chunk->hash);
939         for (n = 0; n < chunk->count; n++)
940                 list_del_init(&chunk->owners[n].list);
941         spin_unlock(&hash_lock);
942         mutex_unlock(&audit_filter_mutex);
943         if (need_prune)
944                 audit_schedule_prune();
945 }
946 
947 static int audit_tree_handle_event(struct fsnotify_group *group,
948                                    struct inode *to_tell,
949                                    struct fsnotify_mark *inode_mark,
950                                    struct fsnotify_mark *vfsmount_mark,
951                                    u32 mask, void *data, int data_type,
952                                    const unsigned char *file_name, u32 cookie)
953 {
954         return 0;
955 }
956 
957 static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
958 {
959         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
960 
961         evict_chunk(chunk);
962 
963         /*
964          * We are guaranteed to have at least one reference to the mark from
965          * either the inode or the caller of fsnotify_destroy_mark().
966          */
967         BUG_ON(atomic_read(&entry->refcnt) < 1);
968 }
969 
970 static const struct fsnotify_ops audit_tree_ops = {
971         .handle_event = audit_tree_handle_event,
972         .freeing_mark = audit_tree_freeing_mark,
973 };
974 
975 static int __init audit_tree_init(void)
976 {
977         int i;
978 
979         audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
980         if (IS_ERR(audit_tree_group))
981                 audit_panic("cannot initialize fsnotify group for rectree watches");
982 
983         for (i = 0; i < HASH_SIZE; i++)
984                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
985 
986         return 0;
987 }
988 __initcall(audit_tree_init);
989 

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