git.oblomov.eu Git - linux-2.6/blob - 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         struct rcu_head head;
  28         struct node {
  29                 struct list_head list;
  30                 struct audit_tree *owner;
  31                 unsigned index;         /* index; upper bit indicates 'will prune' */
  32         } owners[];
  33 };
  34
  35 static LIST_HEAD(tree_list);
  36 static LIST_HEAD(prune_list);
  37
  38 /*
  39  * One struct chunk is attached to each inode of interest.
  40  * We replace struct chunk on tagging/untagging.
  41  * Rules have pointer to struct audit_tree.
  42  * Rules have struct list_head rlist forming a list of rules over
  43  * the same tree.
  44  * References to struct chunk are collected at audit_inode{,_child}()
  45  * time and used in AUDIT_TREE rule matching.
  46  * These references are dropped at the same time we are calling
  47  * audit_free_names(), etc.
  48  *
  49  * Cyclic lists galore:
  50  * tree.chunks anchors chunk.owners[].list                      hash_lock
  51  * tree.rules anchors rule.rlist                                audit_filter_mutex
  52  * chunk.trees anchors tree.same_root                           hash_lock
  53  * chunk.hash is a hash with middle bits of watch.inode as
  54  * a hash function.                                             RCU, hash_lock
  55  *
  56  * tree is refcounted; one reference for "some rules on rules_list refer to
  57  * it", one for each chunk with pointer to it.
  58  *
  59  * chunk is refcounted by embedded inotify_watch.
  60  *
  61  * node.index allows to get from node.list to containing chunk.
  62  * MSB of that sucker is stolen to mark taggings that we might have to
  63  * revert - several operations have very unpleasant cleanup logics and
  64  * that makes a difference.  Some.
  65  */
  66
  67 static struct inotify_handle *rtree_ih;
  68
  69 static struct audit_tree *alloc_tree(const char *s)
  70 {
  71         struct audit_tree *tree;
  72
  73         tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
  74         if (tree) {
  75                 atomic_set(&tree->count, 1);
  76                 tree->goner = 0;
  77                 INIT_LIST_HEAD(&tree->chunks);
  78                 INIT_LIST_HEAD(&tree->rules);
  79                 INIT_LIST_HEAD(&tree->list);
  80                 INIT_LIST_HEAD(&tree->same_root);
  81                 tree->root = NULL;
  82                 strcpy(tree->pathname, s);
  83         }
  84         return tree;
  85 }
  86
  87 static inline void get_tree(struct audit_tree *tree)
  88 {
  89         atomic_inc(&tree->count);
  90 }
  91
  92 static void __put_tree(struct rcu_head *rcu)
  93 {
  94         struct audit_tree *tree = container_of(rcu, struct audit_tree, head);
  95         kfree(tree);
  96 }
  97
  98 static inline void put_tree(struct audit_tree *tree)
  99 {
 100         if (atomic_dec_and_test(&tree->count))
 101                 call_rcu(&tree->head, __put_tree);
 102 }
 103
 104 /* to avoid bringing the entire thing in audit.h */
 105 const char *audit_tree_path(struct audit_tree *tree)
 106 {
 107         return tree->pathname;
 108 }
 109
 110 static struct audit_chunk *alloc_chunk(int count)
 111 {
 112         struct audit_chunk *chunk;
 113         size_t size;
 114         int i;
 115
 116         size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
 117         chunk = kzalloc(size, GFP_KERNEL);
 118         if (!chunk)
 119                 return NULL;
 120
 121         INIT_LIST_HEAD(&chunk->hash);
 122         INIT_LIST_HEAD(&chunk->trees);
 123         chunk->count = count;
 124         for (i = 0; i < count; i++) {
 125                 INIT_LIST_HEAD(&chunk->owners[i].list);
 126                 chunk->owners[i].index = i;
 127         }
 128         inotify_init_watch(&chunk->watch);
 129         return chunk;
 130 }
 131
 132 static void __free_chunk(struct rcu_head *rcu)
 133 {
 134         struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
 135         int i;
 136
 137         for (i = 0; i < chunk->count; i++) {
 138                 if (chunk->owners[i].owner)
 139                         put_tree(chunk->owners[i].owner);
 140         }
 141         kfree(chunk);
 142 }
 143
 144 static inline void free_chunk(struct audit_chunk *chunk)
 145 {
 146         call_rcu(&chunk->head, __free_chunk);
 147 }
 148
 149 void audit_put_chunk(struct audit_chunk *chunk)
 150 {
 151         put_inotify_watch(&chunk->watch);
 152 }
 153
 154 enum {HASH_SIZE = 128};
 155 static struct list_head chunk_hash_heads[HASH_SIZE];
 156 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
 157
 158 static inline struct list_head *chunk_hash(const struct inode *inode)
 159 {
 160         unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
 161         return chunk_hash_heads + n % HASH_SIZE;
 162 }
 163
 164 /* hash_lock is held by caller */
 165 static void insert_hash(struct audit_chunk *chunk)
 166 {
 167         struct list_head *list = chunk_hash(chunk->watch.inode);
 168         list_add_rcu(&chunk->hash, list);
 169 }
 170
 171 /* called under rcu_read_lock */
 172 struct audit_chunk *audit_tree_lookup(const struct inode *inode)
 173 {
 174         struct list_head *list = chunk_hash(inode);
 175         struct audit_chunk *p;
 176
 177         list_for_each_entry_rcu(p, list, hash) {
 178                 if (p->watch.inode == inode) {
 179                         get_inotify_watch(&p->watch);
 180                         return p;
 181                 }
 182         }
 183         return NULL;
 184 }
 185
 186 int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
 187 {
 188         int n;
 189         for (n = 0; n < chunk->count; n++)
 190                 if (chunk->owners[n].owner == tree)
 191                         return 1;
 192         return 0;
 193 }
 194
 195 /* tagging and untagging inodes with trees */
 196
 197 static void untag_chunk(struct audit_chunk *chunk, struct node *p)
 198 {
 199         struct audit_chunk *new;
 200         struct audit_tree *owner;
 201         int size = chunk->count - 1;
 202         int i, j;
 203
 204         mutex_lock(&chunk->watch.inode->inotify_mutex);
 205         if (chunk->dead) {
 206                 mutex_unlock(&chunk->watch.inode->inotify_mutex);
 207                 return;
 208         }
 209
 210         owner = p->owner;
 211
 212         if (!size) {
 213                 chunk->dead = 1;
 214                 spin_lock(&hash_lock);
 215                 list_del_init(&chunk->trees);
 216                 if (owner->root == chunk)
 217                         owner->root = NULL;
 218                 list_del_init(&p->list);
 219                 list_del_rcu(&chunk->hash);
 220                 spin_unlock(&hash_lock);
 221                 inotify_evict_watch(&chunk->watch);
 222                 mutex_unlock(&chunk->watch.inode->inotify_mutex);
 223                 put_inotify_watch(&chunk->watch);
 224                 return;
 225         }
 226
 227         new = alloc_chunk(size);
 228         if (!new)
 229                 goto Fallback;
 230         if (inotify_clone_watch(&chunk->watch, &new->watch) < 0) {
 231                 free_chunk(new);
 232                 goto Fallback;
 233         }
 234
 235         chunk->dead = 1;
 236         spin_lock(&hash_lock);
 237         list_replace_init(&chunk->trees, &new->trees);
 238         if (owner->root == chunk) {
 239                 list_del_init(&owner->same_root);
 240                 owner->root = NULL;
 241         }
 242
 243         for (i = j = 0; i < size; i++, j++) {
 244                 struct audit_tree *s;
 245                 if (&chunk->owners[j] == p) {
 246                         list_del_init(&p->list);
 247                         i--;
 248                         continue;
 249                 }
 250                 s = chunk->owners[j].owner;
 251                 new->owners[i].owner = s;
 252                 new->owners[i].index = chunk->owners[j].index - j + i;
 253                 if (!s) /* result of earlier fallback */
 254                         continue;
 255                 get_tree(s);
 256                 list_replace_init(&chunk->owners[i].list, &new->owners[j].list);
 257         }
 258
 259         list_replace_rcu(&chunk->hash, &new->hash);
 260         list_for_each_entry(owner, &new->trees, same_root)
 261                 owner->root = new;
 262         spin_unlock(&hash_lock);
 263         inotify_evict_watch(&chunk->watch);
 264         mutex_unlock(&chunk->watch.inode->inotify_mutex);
 265         put_inotify_watch(&chunk->watch);
 266         return;
 267
 268 Fallback:
 269         // do the best we can
 270         spin_lock(&hash_lock);
 271         if (owner->root == chunk) {
 272                 list_del_init(&owner->same_root);
 273                 owner->root = NULL;
 274         }
 275         list_del_init(&p->list);
 276         p->owner = NULL;
 277         put_tree(owner);
 278         spin_unlock(&hash_lock);
 279         mutex_unlock(&chunk->watch.inode->inotify_mutex);
 280 }
 281
 282 static int create_chunk(struct inode *inode, struct audit_tree *tree)
 283 {
 284         struct audit_chunk *chunk = alloc_chunk(1);
 285         if (!chunk)
 286                 return -ENOMEM;
 287
 288         if (inotify_add_watch(rtree_ih, &chunk->watch, inode, IN_IGNORED | IN_DELETE_SELF) < 0) {
 289                 free_chunk(chunk);
 290                 return -ENOSPC;
 291         }
 292
 293         mutex_lock(&inode->inotify_mutex);
 294         spin_lock(&hash_lock);
 295         if (tree->goner) {
 296                 spin_unlock(&hash_lock);
 297                 chunk->dead = 1;
 298                 inotify_evict_watch(&chunk->watch);
 299                 mutex_unlock(&inode->inotify_mutex);
 300                 put_inotify_watch(&chunk->watch);
 301                 return 0;
 302         }
 303         chunk->owners[0].index = (1U << 31);
 304         chunk->owners[0].owner = tree;
 305         get_tree(tree);
 306         list_add(&chunk->owners[0].list, &tree->chunks);
 307         if (!tree->root) {
 308                 tree->root = chunk;
 309                 list_add(&tree->same_root, &chunk->trees);
 310         }
 311         insert_hash(chunk);
 312         spin_unlock(&hash_lock);
 313         mutex_unlock(&inode->inotify_mutex);
 314         return 0;
 315 }
 316
 317 /* the first tagged inode becomes root of tree */
 318 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
 319 {
 320         struct inotify_watch *watch;
 321         struct audit_tree *owner;
 322         struct audit_chunk *chunk, *old;
 323         struct node *p;
 324         int n;
 325
 326         if (inotify_find_watch(rtree_ih, inode, &watch) < 0)
 327                 return create_chunk(inode, tree);
 328
 329         old = container_of(watch, struct audit_chunk, watch);
 330
 331         /* are we already there? */
 332         spin_lock(&hash_lock);
 333         for (n = 0; n < old->count; n++) {
 334                 if (old->owners[n].owner == tree) {
 335                         spin_unlock(&hash_lock);
 336                         put_inotify_watch(watch);
 337                         return 0;
 338                 }
 339         }
 340         spin_unlock(&hash_lock);
 341
 342         chunk = alloc_chunk(old->count + 1);
 343         if (!chunk)
 344                 return -ENOMEM;
 345
 346         mutex_lock(&inode->inotify_mutex);
 347         if (inotify_clone_watch(&old->watch, &chunk->watch) < 0) {
 348                 mutex_unlock(&inode->inotify_mutex);
 349                 free_chunk(chunk);
 350                 return -ENOSPC;
 351         }
 352         spin_lock(&hash_lock);
 353         if (tree->goner) {
 354                 spin_unlock(&hash_lock);
 355                 chunk->dead = 1;
 356                 inotify_evict_watch(&chunk->watch);
 357                 mutex_unlock(&inode->inotify_mutex);
 358                 put_inotify_watch(&chunk->watch);
 359                 return 0;
 360         }
 361         list_replace_init(&old->trees, &chunk->trees);
 362         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
 363                 struct audit_tree *s = old->owners[n].owner;
 364                 p->owner = s;
 365                 p->index = old->owners[n].index;
 366                 if (!s) /* result of fallback in untag */
 367                         continue;
 368                 get_tree(s);
 369                 list_replace_init(&old->owners[n].list, &p->list);
 370         }
 371         p->index = (chunk->count - 1) | (1U<<31);
 372         p->owner = tree;
 373         get_tree(tree);
 374         list_add(&p->list, &tree->chunks);
 375         list_replace_rcu(&old->hash, &chunk->hash);
 376         list_for_each_entry(owner, &chunk->trees, same_root)
 377                 owner->root = chunk;
 378         old->dead = 1;
 379         if (!tree->root) {
 380                 tree->root = chunk;
 381                 list_add(&tree->same_root, &chunk->trees);
 382         }
 383         spin_unlock(&hash_lock);
 384         inotify_evict_watch(&old->watch);
 385         mutex_unlock(&inode->inotify_mutex);
 386         put_inotify_watch(&old->watch);
 387         return 0;
 388 }
 389
 390 static struct audit_chunk *find_chunk(struct node *p)
 391 {
 392         int index = p->index & ~(1U<<31);
 393         p -= index;
 394         return container_of(p, struct audit_chunk, owners[0]);
 395 }
 396
 397 static void kill_rules(struct audit_tree *tree)
 398 {
 399         struct audit_krule *rule, *next;
 400         struct audit_entry *entry;
 401         struct audit_buffer *ab;
 402
 403         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
 404                 entry = container_of(rule, struct audit_entry, rule);
 405
 406                 list_del_init(&rule->rlist);
 407                 if (rule->tree) {
 408                         /* not a half-baked one */
 409                         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
 410                         audit_log_format(ab, "op=remove rule dir=");
 411                         audit_log_untrustedstring(ab, rule->tree->pathname);
 412                         if (rule->filterkey) {
 413                                 audit_log_format(ab, " key=");
 414                                 audit_log_untrustedstring(ab, rule->filterkey);
 415                         } else
 416                                 audit_log_format(ab, " key=(null)");
 417                         audit_log_format(ab, " list=%d res=1", rule->listnr);
 418                         audit_log_end(ab);
 419                         rule->tree = NULL;
 420                         list_del_rcu(&entry->list);
 421                         call_rcu(&entry->rcu, audit_free_rule_rcu);
 422                 }
 423         }
 424 }
 425
 426 /*
 427  * finish killing struct audit_tree
 428  */
 429 static void prune_one(struct audit_tree *victim)
 430 {
 431         spin_lock(&hash_lock);
 432         while (!list_empty(&victim->chunks)) {
 433                 struct node *p;
 434                 struct audit_chunk *chunk;
 435
 436                 p = list_entry(victim->chunks.next, struct node, list);
 437                 chunk = find_chunk(p);
 438                 get_inotify_watch(&chunk->watch);
 439                 spin_unlock(&hash_lock);
 440
 441                 untag_chunk(chunk, p);
 442
 443                 put_inotify_watch(&chunk->watch);
 444                 spin_lock(&hash_lock);
 445         }
 446         spin_unlock(&hash_lock);
 447         put_tree(victim);
 448 }
 449
 450 /* trim the uncommitted chunks from tree */
 451
 452 static void trim_marked(struct audit_tree *tree)
 453 {
 454         struct list_head *p, *q;
 455         spin_lock(&hash_lock);
 456         if (tree->goner) {
 457                 spin_unlock(&hash_lock);
 458                 return;
 459         }
 460         /* reorder */
 461         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
 462                 struct node *node = list_entry(p, struct node, list);
 463                 q = p->next;
 464                 if (node->index & (1U<<31)) {
 465                         list_del_init(p);
 466                         list_add(p, &tree->chunks);
 467                 }
 468         }
 469
 470         while (!list_empty(&tree->chunks)) {
 471                 struct node *node;
 472                 struct audit_chunk *chunk;
 473
 474                 node = list_entry(tree->chunks.next, struct node, list);
 475
 476                 /* have we run out of marked? */
 477                 if (!(node->index & (1U<<31)))
 478                         break;
 479
 480                 chunk = find_chunk(node);
 481                 get_inotify_watch(&chunk->watch);
 482                 spin_unlock(&hash_lock);
 483
 484                 untag_chunk(chunk, node);
 485
 486                 put_inotify_watch(&chunk->watch);
 487                 spin_lock(&hash_lock);
 488         }
 489         if (!tree->root && !tree->goner) {
 490                 tree->goner = 1;
 491                 spin_unlock(&hash_lock);
 492                 mutex_lock(&audit_filter_mutex);
 493                 kill_rules(tree);
 494                 list_del_init(&tree->list);
 495                 mutex_unlock(&audit_filter_mutex);
 496                 prune_one(tree);
 497         } else {
 498                 spin_unlock(&hash_lock);
 499         }
 500 }
 501
 502 /* called with audit_filter_mutex */
 503 int audit_remove_tree_rule(struct audit_krule *rule)
 504 {
 505         struct audit_tree *tree;
 506         tree = rule->tree;
 507         if (tree) {
 508                 spin_lock(&hash_lock);
 509                 list_del_init(&rule->rlist);
 510                 if (list_empty(&tree->rules) && !tree->goner) {
 511                         tree->root = NULL;
 512                         list_del_init(&tree->same_root);
 513                         tree->goner = 1;
 514                         list_move(&tree->list, &prune_list);
 515                         rule->tree = NULL;
 516                         spin_unlock(&hash_lock);
 517                         audit_schedule_prune();
 518                         return 1;
 519                 }
 520                 rule->tree = NULL;
 521                 spin_unlock(&hash_lock);
 522                 return 1;
 523         }
 524         return 0;
 525 }
 526
 527 void audit_trim_trees(void)
 528 {
 529         struct list_head cursor;
 530
 531         mutex_lock(&audit_filter_mutex);
 532         list_add(&cursor, &tree_list);
 533         while (cursor.next != &tree_list) {
 534                 struct audit_tree *tree;
 535                 struct nameidata nd;
 536                 struct vfsmount *root_mnt;
 537                 struct node *node;
 538                 struct list_head list;
 539                 int err;
 540
 541                 tree = container_of(cursor.next, struct audit_tree, list);
 542                 get_tree(tree);
 543                 list_del(&cursor);
 544                 list_add(&cursor, &tree->list);
 545                 mutex_unlock(&audit_filter_mutex);
 546
 547                 err = path_lookup(tree->pathname, 0, &nd);
 548                 if (err)
 549                         goto skip_it;
 550
 551                 root_mnt = collect_mounts(nd.path.mnt, nd.path.dentry);
 552                 path_put(&nd.path);
 553                 if (!root_mnt)
 554                         goto skip_it;
 555
 556                 list_add_tail(&list, &root_mnt->mnt_list);
 557                 spin_lock(&hash_lock);
 558                 list_for_each_entry(node, &tree->chunks, list) {
 559                         struct audit_chunk *chunk = find_chunk(node);
 560                         struct inode *inode = chunk->watch.inode;
 561                         struct vfsmount *mnt;
 562                         node->index |= 1U<<31;
 563                         list_for_each_entry(mnt, &list, mnt_list) {
 564                                 if (mnt->mnt_root->d_inode == inode) {
 565                                         node->index &= ~(1U<<31);
 566                                         break;
 567                                 }
 568                         }
 569                 }
 570                 spin_unlock(&hash_lock);
 571                 trim_marked(tree);
 572                 put_tree(tree);
 573                 list_del_init(&list);
 574                 drop_collected_mounts(root_mnt);
 575 skip_it:
 576                 mutex_lock(&audit_filter_mutex);
 577         }
 578         list_del(&cursor);
 579         mutex_unlock(&audit_filter_mutex);
 580 }
 581
 582 static int is_under(struct vfsmount *mnt, struct dentry *dentry,
 583                     struct nameidata *nd)
 584 {
 585         if (mnt != nd->path.mnt) {
 586                 for (;;) {
 587                         if (mnt->mnt_parent == mnt)
 588                                 return 0;
 589                         if (mnt->mnt_parent == nd->path.mnt)
 590                                         break;
 591                         mnt = mnt->mnt_parent;
 592                 }
 593                 dentry = mnt->mnt_mountpoint;
 594         }
 595         return is_subdir(dentry, nd->path.dentry);
 596 }
 597
 598 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
 599 {
 600
 601         if (pathname[0] != '/' ||
 602             rule->listnr != AUDIT_FILTER_EXIT ||
 603             op & ~AUDIT_EQUAL ||
 604             rule->inode_f || rule->watch || rule->tree)
 605                 return -EINVAL;
 606         rule->tree = alloc_tree(pathname);
 607         if (!rule->tree)
 608                 return -ENOMEM;
 609         return 0;
 610 }
 611
 612 void audit_put_tree(struct audit_tree *tree)
 613 {
 614         put_tree(tree);
 615 }
 616
 617 /* called with audit_filter_mutex */
 618 int audit_add_tree_rule(struct audit_krule *rule)
 619 {
 620         struct audit_tree *seed = rule->tree, *tree;
 621         struct nameidata nd;
 622         struct vfsmount *mnt, *p;
 623         struct list_head list;
 624         int err;
 625
 626         list_for_each_entry(tree, &tree_list, list) {
 627                 if (!strcmp(seed->pathname, tree->pathname)) {
 628                         put_tree(seed);
 629                         rule->tree = tree;
 630                         list_add(&rule->rlist, &tree->rules);
 631                         return 0;
 632                 }
 633         }
 634         tree = seed;
 635         list_add(&tree->list, &tree_list);
 636         list_add(&rule->rlist, &tree->rules);
 637         /* do not set rule->tree yet */
 638         mutex_unlock(&audit_filter_mutex);
 639
 640         err = path_lookup(tree->pathname, 0, &nd);
 641         if (err)
 642                 goto Err;
 643         mnt = collect_mounts(nd.path.mnt, nd.path.dentry);
 644         path_put(&nd.path);
 645         if (!mnt) {
 646                 err = -ENOMEM;
 647                 goto Err;
 648         }
 649         list_add_tail(&list, &mnt->mnt_list);
 650
 651         get_tree(tree);
 652         list_for_each_entry(p, &list, mnt_list) {
 653                 err = tag_chunk(p->mnt_root->d_inode, tree);
 654                 if (err)
 655                         break;
 656         }
 657
 658         list_del(&list);
 659         drop_collected_mounts(mnt);
 660
 661         if (!err) {
 662                 struct node *node;
 663                 spin_lock(&hash_lock);
 664                 list_for_each_entry(node, &tree->chunks, list)
 665                         node->index &= ~(1U<<31);
 666                 spin_unlock(&hash_lock);
 667         } else {
 668                 trim_marked(tree);
 669                 goto Err;
 670         }
 671
 672         mutex_lock(&audit_filter_mutex);
 673         if (list_empty(&rule->rlist)) {
 674                 put_tree(tree);
 675                 return -ENOENT;
 676         }
 677         rule->tree = tree;
 678         put_tree(tree);
 679
 680         return 0;
 681 Err:
 682         mutex_lock(&audit_filter_mutex);
 683         list_del_init(&tree->list);
 684         list_del_init(&tree->rules);
 685         put_tree(tree);
 686         return err;
 687 }
 688
 689 int audit_tag_tree(char *old, char *new)
 690 {
 691         struct list_head cursor, barrier;
 692         int failed = 0;
 693         struct nameidata nd;
 694         struct vfsmount *tagged;
 695         struct list_head list;
 696         struct vfsmount *mnt;
 697         struct dentry *dentry;
 698         int err;
 699
 700         err = path_lookup(new, 0, &nd);
 701         if (err)
 702                 return err;
 703         tagged = collect_mounts(nd.path.mnt, nd.path.dentry);
 704         path_put(&nd.path);
 705         if (!tagged)
 706                 return -ENOMEM;
 707
 708         err = path_lookup(old, 0, &nd);
 709         if (err) {
 710                 drop_collected_mounts(tagged);
 711                 return err;
 712         }
 713         mnt = mntget(nd.path.mnt);
 714         dentry = dget(nd.path.dentry);
 715         path_put(&nd.path);
 716
 717         if (dentry == tagged->mnt_root && dentry == mnt->mnt_root)
 718                 follow_up(&mnt, &dentry);
 719
 720         list_add_tail(&list, &tagged->mnt_list);
 721
 722         mutex_lock(&audit_filter_mutex);
 723         list_add(&barrier, &tree_list);
 724         list_add(&cursor, &barrier);
 725
 726         while (cursor.next != &tree_list) {
 727                 struct audit_tree *tree;
 728                 struct vfsmount *p;
 729
 730                 tree = container_of(cursor.next, struct audit_tree, list);
 731                 get_tree(tree);
 732                 list_del(&cursor);
 733                 list_add(&cursor, &tree->list);
 734                 mutex_unlock(&audit_filter_mutex);
 735
 736                 err = path_lookup(tree->pathname, 0, &nd);
 737                 if (err) {
 738                         put_tree(tree);
 739                         mutex_lock(&audit_filter_mutex);
 740                         continue;
 741                 }
 742
 743                 spin_lock(&vfsmount_lock);
 744                 if (!is_under(mnt, dentry, &nd)) {
 745                         spin_unlock(&vfsmount_lock);
 746                         path_put(&nd.path);
 747                         put_tree(tree);
 748                         mutex_lock(&audit_filter_mutex);
 749                         continue;
 750                 }
 751                 spin_unlock(&vfsmount_lock);
 752                 path_put(&nd.path);
 753
 754                 list_for_each_entry(p, &list, mnt_list) {
 755                         failed = tag_chunk(p->mnt_root->d_inode, tree);
 756                         if (failed)
 757                                 break;
 758                 }
 759
 760                 if (failed) {
 761                         put_tree(tree);
 762                         mutex_lock(&audit_filter_mutex);
 763                         break;
 764                 }
 765
 766                 mutex_lock(&audit_filter_mutex);
 767                 spin_lock(&hash_lock);
 768                 if (!tree->goner) {
 769                         list_del(&tree->list);
 770                         list_add(&tree->list, &tree_list);
 771                 }
 772                 spin_unlock(&hash_lock);
 773                 put_tree(tree);
 774         }
 775
 776         while (barrier.prev != &tree_list) {
 777                 struct audit_tree *tree;
 778
 779                 tree = container_of(barrier.prev, struct audit_tree, list);
 780                 get_tree(tree);
 781                 list_del(&tree->list);
 782                 list_add(&tree->list, &barrier);
 783                 mutex_unlock(&audit_filter_mutex);
 784
 785                 if (!failed) {
 786                         struct node *node;
 787                         spin_lock(&hash_lock);
 788                         list_for_each_entry(node, &tree->chunks, list)
 789                                 node->index &= ~(1U<<31);
 790                         spin_unlock(&hash_lock);
 791                 } else {
 792                         trim_marked(tree);
 793                 }
 794
 795                 put_tree(tree);
 796                 mutex_lock(&audit_filter_mutex);
 797         }
 798         list_del(&barrier);
 799         list_del(&cursor);
 800         list_del(&list);
 801         mutex_unlock(&audit_filter_mutex);
 802         dput(dentry);
 803         mntput(mnt);
 804         drop_collected_mounts(tagged);
 805         return failed;
 806 }
 807
 808 /*
 809  * That gets run when evict_chunk() ends up needing to kill audit_tree.
 810  * Runs from a separate thread, with audit_cmd_mutex held.
 811  */
 812 void audit_prune_trees(void)
 813 {
 814         mutex_lock(&audit_filter_mutex);
 815
 816         while (!list_empty(&prune_list)) {
 817                 struct audit_tree *victim;
 818
 819                 victim = list_entry(prune_list.next, struct audit_tree, list);
 820                 list_del_init(&victim->list);
 821
 822                 mutex_unlock(&audit_filter_mutex);
 823
 824                 prune_one(victim);
 825
 826                 mutex_lock(&audit_filter_mutex);
 827         }
 828
 829         mutex_unlock(&audit_filter_mutex);
 830 }
 831
 832 /*
 833  *  Here comes the stuff asynchronous to auditctl operations
 834  */
 835
 836 /* inode->inotify_mutex is locked */
 837 static void evict_chunk(struct audit_chunk *chunk)
 838 {
 839         struct audit_tree *owner;
 840         int n;
 841
 842         if (chunk->dead)
 843                 return;
 844
 845         chunk->dead = 1;
 846         mutex_lock(&audit_filter_mutex);
 847         spin_lock(&hash_lock);
 848         while (!list_empty(&chunk->trees)) {
 849                 owner = list_entry(chunk->trees.next,
 850                                    struct audit_tree, same_root);
 851                 owner->goner = 1;
 852                 owner->root = NULL;
 853                 list_del_init(&owner->same_root);
 854                 spin_unlock(&hash_lock);
 855                 kill_rules(owner);
 856                 list_move(&owner->list, &prune_list);
 857                 audit_schedule_prune();
 858                 spin_lock(&hash_lock);
 859         }
 860         list_del_rcu(&chunk->hash);
 861         for (n = 0; n < chunk->count; n++)
 862                 list_del_init(&chunk->owners[n].list);
 863         spin_unlock(&hash_lock);
 864         mutex_unlock(&audit_filter_mutex);
 865 }
 866
 867 static void handle_event(struct inotify_watch *watch, u32 wd, u32 mask,
 868                          u32 cookie, const char *dname, struct inode *inode)
 869 {
 870         struct audit_chunk *chunk = container_of(watch, struct audit_chunk, watch);
 871
 872         if (mask & IN_IGNORED) {
 873                 evict_chunk(chunk);
 874                 put_inotify_watch(watch);
 875         }
 876 }
 877
 878 static void destroy_watch(struct inotify_watch *watch)
 879 {
 880         struct audit_chunk *chunk = container_of(watch, struct audit_chunk, watch);
 881         free_chunk(chunk);
 882 }
 883
 884 static const struct inotify_operations rtree_inotify_ops = {
 885         .handle_event   = handle_event,
 886         .destroy_watch  = destroy_watch,
 887 };
 888
 889 static int __init audit_tree_init(void)
 890 {
 891         int i;
 892
 893         rtree_ih = inotify_init(&rtree_inotify_ops);
 894         if (IS_ERR(rtree_ih))
 895                 audit_panic("cannot initialize inotify handle for rectree watches");
 896
 897         for (i = 0; i < HASH_SIZE; i++)
 898                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
 899
 900         return 0;
 901 }
 902 __initcall(audit_tree_init);