kernel/audit_tree.c

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