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   1 #include "audit.h"
   2 #include <linux/inotify.h>
   3 #include <linux/namei.h>
   4 #include <linux/mount.h>
   5 #include <linux/kthread.h>
   6
   7 struct audit_tree;
   8 struct audit_chunk;
   9
  10 struct audit_tree {
  11         atomic_t count;
  12         int goner;
  13         struct audit_chunk *root;
  14         struct list_head chunks;
  15         struct list_head rules;
  16         struct list_head list;
  17         struct list_head same_root;
  18         struct rcu_head head;
  19         char pathname[];
  20 };
  21
  22 struct audit_chunk {
  23         struct list_head hash;
  24         struct inotify_watch watch;
  25         struct list_head trees;         /* with root here */
  26         int dead;
  27         int count;
  28         atomic_long_t refs;
  29         struct rcu_head head;
  30         struct node {
  31                 struct list_head list;
  32                 struct audit_tree *owner;
  33                 unsigned index;         /* index; upper bit indicates 'will prune' */
  34         } owners[];
  35 };
  36
  37 static LIST_HEAD(tree_list);
  38 static LIST_HEAD(prune_list);
  39
  40 /*
  41  * One struct chunk is attached to each inode of interest.
  42  * We replace struct chunk on tagging/untagging.
  43  * Rules have pointer to struct audit_tree.
  44  * Rules have struct list_head rlist forming a list of rules over
  45  * the same tree.
  46  * References to struct chunk are collected at audit_inode{,_child}()
  47  * time and used in AUDIT_TREE rule matching.
  48  * These references are dropped at the same time we are calling
  49  * audit_free_names(), etc.
  50  *
  51  * Cyclic lists galore:
  52  * tree.chunks anchors chunk.owners[].list                      hash_lock
  53  * tree.rules anchors rule.rlist                                audit_filter_mutex
  54  * chunk.trees anchors tree.same_root                           hash_lock
  55  * chunk.hash is a hash with middle bits of watch.inode as
  56  * a hash function.                                             RCU, hash_lock
  57  *
  58  * tree is refcounted; one reference for "some rules on rules_list refer to
  59  * it", one for each chunk with pointer to it.
  60  *
  61  * chunk is refcounted by embedded inotify_watch + .refs (non-zero refcount
  62  * of watch contributes 1 to .refs).
  63  *
  64  * node.index allows to get from node.list to containing chunk.
  65  * MSB of that sucker is stolen to mark taggings that we might have to
  66  * revert - several operations have very unpleasant cleanup logics and
  67  * that makes a difference.  Some.
  68  */
  69
  70 static struct inotify_handle *rtree_ih;
  71
  72 static struct audit_tree *alloc_tree(const char *s)
  73 {
  74         struct audit_tree *tree;
  75
  76         tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
  77         if (tree) {
  78                 atomic_set(&tree->count, 1);
  79                 tree->goner = 0;
  80                 INIT_LIST_HEAD(&tree->chunks);
  81                 INIT_LIST_HEAD(&tree->rules);
  82                 INIT_LIST_HEAD(&tree->list);
  83                 INIT_LIST_HEAD(&tree->same_root);
  84                 tree->root = NULL;
  85                 strcpy(tree->pathname, s);
  86         }
  87         return tree;
  88 }
  89
  90 static inline void get_tree(struct audit_tree *tree)
  91 {
  92         atomic_inc(&tree->count);
  93 }
  94
  95 static void __put_tree(struct rcu_head *rcu)
  96 {
  97         struct audit_tree *tree = container_of(rcu, struct audit_tree, head);
  98         kfree(tree);
  99 }
 100
 101 static inline void put_tree(struct audit_tree *tree)
 102 {
 103         if (atomic_dec_and_test(&tree->count))
 104                 call_rcu(&tree->head, __put_tree);
 105 }
 106
 107 /* to avoid bringing the entire thing in audit.h */
 108 const char *audit_tree_path(struct audit_tree *tree)
 109 {
 110         return tree->pathname;
 111 }
 112
 113 static struct audit_chunk *alloc_chunk(int count)
 114 {
 115         struct audit_chunk *chunk;
 116         size_t size;
 117         int i;
 118
 119         size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
 120         chunk = kzalloc(size, GFP_KERNEL);
 121         if (!chunk)
 122                 return NULL;
 123
 124         INIT_LIST_HEAD(&chunk->hash);
 125         INIT_LIST_HEAD(&chunk->trees);
 126         chunk->count = count;
 127         atomic_long_set(&chunk->refs, 1);
 128         for (i = 0; i < count; i++) {
 129                 INIT_LIST_HEAD(&chunk->owners[i].list);
 130                 chunk->owners[i].index = i;
 131         }
 132         inotify_init_watch(&chunk->watch);
 133         return chunk;
 134 }
 135
 136 static void free_chunk(struct audit_chunk *chunk)
 137 {
 138         int i;
 139
 140         for (i = 0; i < chunk->count; i++) {
 141                 if (chunk->owners[i].owner)
 142                         put_tree(chunk->owners[i].owner);
 143         }
 144         kfree(chunk);
 145 }
 146
 147 void audit_put_chunk(struct audit_chunk *chunk)
 148 {
 149         if (atomic_long_dec_and_test(&chunk->refs))
 150                 free_chunk(chunk);
 151 }
 152
 153 static void __put_chunk(struct rcu_head *rcu)
 154 {
 155         struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
 156         audit_put_chunk(chunk);
 157 }
 158
 159 enum {HASH_SIZE = 128};
 160 static struct list_head chunk_hash_heads[HASH_SIZE];
 161 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
 162
 163 static inline struct list_head *chunk_hash(const struct inode *inode)
 164 {
 165         unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
 166         return chunk_hash_heads + n % HASH_SIZE;
 167 }
 168
 169 /* hash_lock is held by caller */
 170 static void insert_hash(struct audit_chunk *chunk)
 171 {
 172         struct list_head *list = chunk_hash(chunk->watch.inode);
 173         list_add_rcu(&chunk->hash, list);
 174 }
 175
 176 /* called under rcu_read_lock */
 177 struct audit_chunk *audit_tree_lookup(const struct inode *inode)
 178 {
 179         struct list_head *list = chunk_hash(inode);
 180         struct audit_chunk *p;
 181
 182         list_for_each_entry_rcu(p, list, hash) {
 183                 if (p->watch.inode == inode) {
 184                         atomic_long_inc(&p->refs);
 185                         return p;
 186                 }
 187         }
 188         return NULL;
 189 }
 190
 191 int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
 192 {
 193         int n;
 194         for (n = 0; n < chunk->count; n++)
 195                 if (chunk->owners[n].owner == tree)
 196                         return 1;
 197         return 0;
 198 }
 199
 200 /* tagging and untagging inodes with trees */
 201
 202 static struct audit_chunk *find_chunk(struct node *p)
 203 {
 204         int index = p->index & ~(1U<<31);
 205         p -= index;
 206         return container_of(p, struct audit_chunk, owners[0]);
 207 }
 208
 209 static void untag_chunk(struct node *p)
 210 {
 211         struct audit_chunk *chunk = find_chunk(p);
 212         struct audit_chunk *new;
 213         struct audit_tree *owner;
 214         int size = chunk->count - 1;
 215         int i, j;
 216
 217         if (!pin_inotify_watch(&chunk->watch)) {
 218                 /*
 219                  * Filesystem is shutting down; all watches are getting
 220                  * evicted, just take it off the node list for this
 221                  * tree and let the eviction logics take care of the
 222                  * rest.
 223                  */
 224                 owner = p->owner;
 225                 if (owner->root == chunk) {
 226                         list_del_init(&owner->same_root);
 227                         owner->root = NULL;
 228                 }
 229                 list_del_init(&p->list);
 230                 p->owner = NULL;
 231                 put_tree(owner);
 232                 return;
 233         }
 234
 235         spin_unlock(&hash_lock);
 236
 237         /*
 238          * pin_inotify_watch() succeeded, so the watch won't go away
 239          * from under us.
 240          */
 241         mutex_lock(&chunk->watch.inode->inotify_mutex);
 242         if (chunk->dead) {
 243                 mutex_unlock(&chunk->watch.inode->inotify_mutex);
 244                 goto out;
 245         }
 246
 247         owner = p->owner;
 248
 249         if (!size) {
 250                 chunk->dead = 1;
 251                 spin_lock(&hash_lock);
 252                 list_del_init(&chunk->trees);
 253                 if (owner->root == chunk)
 254                         owner->root = NULL;
 255                 list_del_init(&p->list);
 256                 list_del_rcu(&chunk->hash);
 257                 spin_unlock(&hash_lock);
 258                 inotify_evict_watch(&chunk->watch);
 259                 mutex_unlock(&chunk->watch.inode->inotify_mutex);
 260                 put_inotify_watch(&chunk->watch);
 261                 goto out;
 262         }
 263
 264         new = alloc_chunk(size);
 265         if (!new)
 266                 goto Fallback;
 267         if (inotify_clone_watch(&chunk->watch, &new->watch) < 0) {
 268                 free_chunk(new);
 269                 goto Fallback;
 270         }
 271
 272         chunk->dead = 1;
 273         spin_lock(&hash_lock);
 274         list_replace_init(&chunk->trees, &new->trees);
 275         if (owner->root == chunk) {
 276                 list_del_init(&owner->same_root);
 277                 owner->root = NULL;
 278         }
 279
 280         for (i = j = 0; j <= size; i++, j++) {
 281                 struct audit_tree *s;
 282                 if (&chunk->owners[j] == p) {
 283                         list_del_init(&p->list);
 284                         i--;
 285                         continue;
 286                 }
 287                 s = chunk->owners[j].owner;
 288                 new->owners[i].owner = s;
 289                 new->owners[i].index = chunk->owners[j].index - j + i;
 290                 if (!s) /* result of earlier fallback */
 291                         continue;
 292                 get_tree(s);
 293                 list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
 294         }
 295
 296         list_replace_rcu(&chunk->hash, &new->hash);
 297         list_for_each_entry(owner, &new->trees, same_root)
 298                 owner->root = new;
 299         spin_unlock(&hash_lock);
 300         inotify_evict_watch(&chunk->watch);
 301         mutex_unlock(&chunk->watch.inode->inotify_mutex);
 302         put_inotify_watch(&chunk->watch);
 303         goto out;
 304
 305 Fallback:
 306         // do the best we can
 307         spin_lock(&hash_lock);
 308         if (owner->root == chunk) {
 309                 list_del_init(&owner->same_root);
 310                 owner->root = NULL;
 311         }
 312         list_del_init(&p->list);
 313         p->owner = NULL;
 314         put_tree(owner);
 315         spin_unlock(&hash_lock);
 316         mutex_unlock(&chunk->watch.inode->inotify_mutex);
 317 out:
 318         unpin_inotify_watch(&chunk->watch);
 319         spin_lock(&hash_lock);
 320 }
 321
 322 static int create_chunk(struct inode *inode, struct audit_tree *tree)
 323 {
 324         struct audit_chunk *chunk = alloc_chunk(1);
 325         if (!chunk)
 326                 return -ENOMEM;
 327
 328         if (inotify_add_watch(rtree_ih, &chunk->watch, inode, IN_IGNORED | IN_DELETE_SELF) < 0) {
 329                 free_chunk(chunk);
 330                 return -ENOSPC;
 331         }
 332
 333         mutex_lock(&inode->inotify_mutex);
 334         spin_lock(&hash_lock);
 335         if (tree->goner) {
 336                 spin_unlock(&hash_lock);
 337                 chunk->dead = 1;
 338                 inotify_evict_watch(&chunk->watch);
 339                 mutex_unlock(&inode->inotify_mutex);
 340                 put_inotify_watch(&chunk->watch);
 341                 return 0;
 342         }
 343         chunk->owners[0].index = (1U << 31);
 344         chunk->owners[0].owner = tree;
 345         get_tree(tree);
 346         list_add(&chunk->owners[0].list, &tree->chunks);
 347         if (!tree->root) {
 348                 tree->root = chunk;
 349                 list_add(&tree->same_root, &chunk->trees);
 350         }
 351         insert_hash(chunk);
 352         spin_unlock(&hash_lock);
 353         mutex_unlock(&inode->inotify_mutex);
 354         return 0;
 355 }
 356
 357 /* the first tagged inode becomes root of tree */
 358 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
 359 {
 360         struct inotify_watch *watch;
 361         struct audit_tree *owner;
 362         struct audit_chunk *chunk, *old;
 363         struct node *p;
 364         int n;
 365
 366         if (inotify_find_watch(rtree_ih, inode, &watch) < 0)
 367                 return create_chunk(inode, tree);
 368
 369         old = container_of(watch, struct audit_chunk, watch);
 370
 371         /* are we already there? */
 372         spin_lock(&hash_lock);
 373         for (n = 0; n < old->count; n++) {
 374                 if (old->owners[n].owner == tree) {
 375                         spin_unlock(&hash_lock);
 376                         put_inotify_watch(&old->watch);
 377                         return 0;
 378                 }
 379         }
 380         spin_unlock(&hash_lock);
 381
 382         chunk = alloc_chunk(old->count + 1);
 383         if (!chunk) {
 384                 put_inotify_watch(&old->watch);
 385                 return -ENOMEM;
 386         }
 387
 388         mutex_lock(&inode->inotify_mutex);
 389         if (inotify_clone_watch(&old->watch, &chunk->watch) < 0) {
 390                 mutex_unlock(&inode->inotify_mutex);
 391                 put_inotify_watch(&old->watch);
 392                 free_chunk(chunk);
 393                 return -ENOSPC;
 394         }
 395         spin_lock(&hash_lock);
 396         if (tree->goner) {
 397                 spin_unlock(&hash_lock);
 398                 chunk->dead = 1;
 399                 inotify_evict_watch(&chunk->watch);
 400                 mutex_unlock(&inode->inotify_mutex);
 401                 put_inotify_watch(&old->watch);
 402                 put_inotify_watch(&chunk->watch);
 403                 return 0;
 404         }
 405         list_replace_init(&old->trees, &chunk->trees);
 406         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
 407                 struct audit_tree *s = old->owners[n].owner;
 408                 p->owner = s;
 409                 p->index = old->owners[n].index;
 410                 if (!s) /* result of fallback in untag */
 411                         continue;
 412                 get_tree(s);
 413                 list_replace_init(&old->owners[n].list, &p->list);
 414         }
 415         p->index = (chunk->count - 1) | (1U<<31);
 416         p->owner = tree;
 417         get_tree(tree);
 418         list_add(&p->list, &tree->chunks);
 419         list_replace_rcu(&old->hash, &chunk->hash);
 420         list_for_each_entry(owner, &chunk->trees, same_root)
 421                 owner->root = chunk;
 422         old->dead = 1;
 423         if (!tree->root) {
 424                 tree->root = chunk;
 425                 list_add(&tree->same_root, &chunk->trees);
 426         }
 427         spin_unlock(&hash_lock);
 428         inotify_evict_watch(&old->watch);
 429         mutex_unlock(&inode->inotify_mutex);
 430         put_inotify_watch(&old->watch); /* pair to inotify_find_watch */
 431         put_inotify_watch(&old->watch); /* and kill it */
 432         return 0;
 433 }
 434
 435 static void kill_rules(struct audit_tree *tree)
 436 {
 437         struct audit_krule *rule, *next;
 438         struct audit_entry *entry;
 439         struct audit_buffer *ab;
 440
 441         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
 442                 entry = container_of(rule, struct audit_entry, rule);
 443
 444                 list_del_init(&rule->rlist);
 445                 if (rule->tree) {
 446                         /* not a half-baked one */
 447                         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
 448                         audit_log_format(ab, "op=");
 449                         audit_log_string(ab, "remove rule");
 450                         audit_log_format(ab, " dir=");
 451                         audit_log_untrustedstring(ab, rule->tree->pathname);
 452                         audit_log_key(ab, rule->filterkey);
 453                         audit_log_format(ab, " list=%d res=1", rule->listnr);
 454                         audit_log_end(ab);
 455                         rule->tree = NULL;
 456                         list_del_rcu(&entry->list);
 457                         list_del(&entry->rule.list);
 458                         call_rcu(&entry->rcu, audit_free_rule_rcu);
 459                 }
 460         }
 461 }
 462
 463 /*
 464  * finish killing struct audit_tree
 465  */
 466 static void prune_one(struct audit_tree *victim)
 467 {
 468         spin_lock(&hash_lock);
 469         while (!list_empty(&victim->chunks)) {
 470                 struct node *p;
 471
 472                 p = list_entry(victim->chunks.next, struct node, list);
 473
 474                 untag_chunk(p);
 475         }
 476         spin_unlock(&hash_lock);
 477         put_tree(victim);
 478 }
 479
 480 /* trim the uncommitted chunks from tree */
 481
 482 static void trim_marked(struct audit_tree *tree)
 483 {
 484         struct list_head *p, *q;
 485         spin_lock(&hash_lock);
 486         if (tree->goner) {
 487                 spin_unlock(&hash_lock);
 488                 return;
 489         }
 490         /* reorder */
 491         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
 492                 struct node *node = list_entry(p, struct node, list);
 493                 q = p->next;
 494                 if (node->index & (1U<<31)) {
 495                         list_del_init(p);
 496                         list_add(p, &tree->chunks);
 497                 }
 498         }
 499
 500         while (!list_empty(&tree->chunks)) {
 501                 struct node *node;
 502
 503                 node = list_entry(tree->chunks.next, struct node, list);
 504
 505                 /* have we run out of marked? */
 506                 if (!(node->index & (1U<<31)))
 507                         break;
 508
 509                 untag_chunk(node);
 510         }
 511         if (!tree->root && !tree->goner) {
 512                 tree->goner = 1;
 513                 spin_unlock(&hash_lock);
 514                 mutex_lock(&audit_filter_mutex);
 515                 kill_rules(tree);
 516                 list_del_init(&tree->list);
 517                 mutex_unlock(&audit_filter_mutex);
 518                 prune_one(tree);
 519         } else {
 520                 spin_unlock(&hash_lock);
 521         }
 522 }
 523
 524 static void audit_schedule_prune(void);
 525
 526 /* called with audit_filter_mutex */
 527 int audit_remove_tree_rule(struct audit_krule *rule)
 528 {
 529         struct audit_tree *tree;
 530         tree = rule->tree;
 531         if (tree) {
 532                 spin_lock(&hash_lock);
 533                 list_del_init(&rule->rlist);
 534                 if (list_empty(&tree->rules) && !tree->goner) {
 535                         tree->root = NULL;
 536                         list_del_init(&tree->same_root);
 537                         tree->goner = 1;
 538                         list_move(&tree->list, &prune_list);
 539                         rule->tree = NULL;
 540                         spin_unlock(&hash_lock);
 541                         audit_schedule_prune();
 542                         return 1;
 543                 }
 544                 rule->tree = NULL;
 545                 spin_unlock(&hash_lock);
 546                 return 1;
 547         }
 548         return 0;
 549 }
 550
 551 void audit_trim_trees(void)
 552 {
 553         struct list_head cursor;
 554
 555         mutex_lock(&audit_filter_mutex);
 556         list_add(&cursor, &tree_list);
 557         while (cursor.next != &tree_list) {
 558                 struct audit_tree *tree;
 559                 struct path path;
 560                 struct vfsmount *root_mnt;
 561                 struct node *node;
 562                 struct list_head list;
 563                 int err;
 564
 565                 tree = container_of(cursor.next, struct audit_tree, list);
 566                 get_tree(tree);
 567                 list_del(&cursor);
 568                 list_add(&cursor, &tree->list);
 569                 mutex_unlock(&audit_filter_mutex);
 570
 571                 err = kern_path(tree->pathname, 0, &path);
 572                 if (err)
 573                         goto skip_it;
 574
 575                 root_mnt = collect_mounts(&path);
 576                 path_put(&path);
 577                 if (!root_mnt)
 578                         goto skip_it;
 579
 580                 list_add_tail(&list, &root_mnt->mnt_list);
 581                 spin_lock(&hash_lock);
 582                 list_for_each_entry(node, &tree->chunks, list) {
 583                         struct audit_chunk *chunk = find_chunk(node);
 584                         struct inode *inode = chunk->watch.inode;
 585                         struct vfsmount *mnt;
 586                         node->index |= 1U<<31;
 587                         list_for_each_entry(mnt, &list, mnt_list) {
 588                                 if (mnt->mnt_root->d_inode == inode) {
 589                                         node->index &= ~(1U<<31);
 590                                         break;
 591                                 }
 592                         }
 593                 }
 594                 spin_unlock(&hash_lock);
 595                 trim_marked(tree);
 596                 put_tree(tree);
 597                 list_del_init(&list);
 598                 drop_collected_mounts(root_mnt);
 599 skip_it:
 600                 mutex_lock(&audit_filter_mutex);
 601         }
 602         list_del(&cursor);
 603         mutex_unlock(&audit_filter_mutex);
 604 }
 605
 606 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
 607 {
 608
 609         if (pathname[0] != '/' ||
 610             rule->listnr != AUDIT_FILTER_EXIT ||
 611             op != Audit_equal ||
 612             rule->inode_f || rule->watch || rule->tree)
 613                 return -EINVAL;
 614         rule->tree = alloc_tree(pathname);
 615         if (!rule->tree)
 616                 return -ENOMEM;
 617         return 0;
 618 }
 619
 620 void audit_put_tree(struct audit_tree *tree)
 621 {
 622         put_tree(tree);
 623 }
 624
 625 /* called with audit_filter_mutex */
 626 int audit_add_tree_rule(struct audit_krule *rule)
 627 {
 628         struct audit_tree *seed = rule->tree, *tree;
 629         struct path path;
 630         struct vfsmount *mnt, *p;
 631         struct list_head list;
 632         int err;
 633
 634         list_for_each_entry(tree, &tree_list, list) {
 635                 if (!strcmp(seed->pathname, tree->pathname)) {
 636                         put_tree(seed);
 637                         rule->tree = tree;
 638                         list_add(&rule->rlist, &tree->rules);
 639                         return 0;
 640                 }
 641         }
 642         tree = seed;
 643         list_add(&tree->list, &tree_list);
 644         list_add(&rule->rlist, &tree->rules);
 645         /* do not set rule->tree yet */
 646         mutex_unlock(&audit_filter_mutex);
 647
 648         err = kern_path(tree->pathname, 0, &path);
 649         if (err)
 650                 goto Err;
 651         mnt = collect_mounts(&path);
 652         path_put(&path);
 653         if (!mnt) {
 654                 err = -ENOMEM;
 655                 goto Err;
 656         }
 657         list_add_tail(&list, &mnt->mnt_list);
 658
 659         get_tree(tree);
 660         list_for_each_entry(p, &list, mnt_list) {
 661                 err = tag_chunk(p->mnt_root->d_inode, tree);
 662                 if (err)
 663                         break;
 664         }
 665
 666         list_del(&list);
 667         drop_collected_mounts(mnt);
 668
 669         if (!err) {
 670                 struct node *node;
 671                 spin_lock(&hash_lock);
 672                 list_for_each_entry(node, &tree->chunks, list)
 673                         node->index &= ~(1U<<31);
 674                 spin_unlock(&hash_lock);
 675         } else {
 676                 trim_marked(tree);
 677                 goto Err;
 678         }
 679
 680         mutex_lock(&audit_filter_mutex);
 681         if (list_empty(&rule->rlist)) {
 682                 put_tree(tree);
 683                 return -ENOENT;
 684         }
 685         rule->tree = tree;
 686         put_tree(tree);
 687
 688         return 0;
 689 Err:
 690         mutex_lock(&audit_filter_mutex);
 691         list_del_init(&tree->list);
 692         list_del_init(&tree->rules);
 693         put_tree(tree);
 694         return err;
 695 }
 696
 697 int audit_tag_tree(char *old, char *new)
 698 {
 699         struct list_head cursor, barrier;
 700         int failed = 0;
 701         struct path path1, path2;
 702         struct vfsmount *tagged;
 703         struct list_head list;
 704         int err;
 705
 706         err = kern_path(new, 0, &path2);
 707         if (err)
 708                 return err;
 709         tagged = collect_mounts(&path2);
 710         path_put(&path2);
 711         if (!tagged)
 712                 return -ENOMEM;
 713
 714         err = kern_path(old, 0, &path1);
 715         if (err) {
 716                 drop_collected_mounts(tagged);
 717                 return err;
 718         }
 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                 int good_one = 0;
 730
 731                 tree = container_of(cursor.next, struct audit_tree, list);
 732                 get_tree(tree);
 733                 list_del(&cursor);
 734                 list_add(&cursor, &tree->list);
 735                 mutex_unlock(&audit_filter_mutex);
 736
 737                 err = kern_path(tree->pathname, 0, &path2);
 738                 if (!err) {
 739                         good_one = path_is_under(&path1, &path2);
 740                         path_put(&path2);
 741                 }
 742
 743                 if (!good_one) {
 744                         put_tree(tree);
 745                         mutex_lock(&audit_filter_mutex);
 746                         continue;
 747                 }
 748
 749                 list_for_each_entry(p, &list, mnt_list) {
 750                         failed = tag_chunk(p->mnt_root->d_inode, tree);
 751                         if (failed)
 752                                 break;
 753                 }
 754
 755                 if (failed) {
 756                         put_tree(tree);
 757                         mutex_lock(&audit_filter_mutex);
 758                         break;
 759                 }
 760
 761                 mutex_lock(&audit_filter_mutex);
 762                 spin_lock(&hash_lock);
 763                 if (!tree->goner) {
 764                         list_del(&tree->list);
 765                         list_add(&tree->list, &tree_list);
 766                 }
 767                 spin_unlock(&hash_lock);
 768                 put_tree(tree);
 769         }
 770
 771         while (barrier.prev != &tree_list) {
 772                 struct audit_tree *tree;
 773
 774                 tree = container_of(barrier.prev, struct audit_tree, list);
 775                 get_tree(tree);
 776                 list_del(&tree->list);
 777                 list_add(&tree->list, &barrier);
 778                 mutex_unlock(&audit_filter_mutex);
 779
 780                 if (!failed) {
 781                         struct node *node;
 782                         spin_lock(&hash_lock);
 783                         list_for_each_entry(node, &tree->chunks, list)
 784                                 node->index &= ~(1U<<31);
 785                         spin_unlock(&hash_lock);
 786                 } else {
 787                         trim_marked(tree);
 788                 }
 789
 790                 put_tree(tree);
 791                 mutex_lock(&audit_filter_mutex);
 792         }
 793         list_del(&barrier);
 794         list_del(&cursor);
 795         list_del(&list);
 796         mutex_unlock(&audit_filter_mutex);
 797         path_put(&path1);
 798         drop_collected_mounts(tagged);
 799         return failed;
 800 }
 801
 802 /*
 803  * That gets run when evict_chunk() ends up needing to kill audit_tree.
 804  * Runs from a separate thread.
 805  */
 806 static int prune_tree_thread(void *unused)
 807 {
 808         mutex_lock(&audit_cmd_mutex);
 809         mutex_lock(&audit_filter_mutex);
 810
 811         while (!list_empty(&prune_list)) {
 812                 struct audit_tree *victim;
 813
 814                 victim = list_entry(prune_list.next, struct audit_tree, list);
 815                 list_del_init(&victim->list);
 816
 817                 mutex_unlock(&audit_filter_mutex);
 818
 819                 prune_one(victim);
 820
 821                 mutex_lock(&audit_filter_mutex);
 822         }
 823
 824         mutex_unlock(&audit_filter_mutex);
 825         mutex_unlock(&audit_cmd_mutex);
 826         return 0;
 827 }
 828
 829 static void audit_schedule_prune(void)
 830 {
 831         kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
 832 }
 833
 834 /*
 835  * ... and that one is done if evict_chunk() decides to delay until the end
 836  * of syscall.  Runs synchronously.
 837  */
 838 void audit_kill_trees(struct list_head *list)
 839 {
 840         mutex_lock(&audit_cmd_mutex);
 841         mutex_lock(&audit_filter_mutex);
 842
 843         while (!list_empty(list)) {
 844                 struct audit_tree *victim;
 845
 846                 victim = list_entry(list->next, struct audit_tree, list);
 847                 kill_rules(victim);
 848                 list_del_init(&victim->list);
 849
 850                 mutex_unlock(&audit_filter_mutex);
 851
 852                 prune_one(victim);
 853
 854                 mutex_lock(&audit_filter_mutex);
 855         }
 856
 857         mutex_unlock(&audit_filter_mutex);
 858         mutex_unlock(&audit_cmd_mutex);
 859 }
 860
 861 /*
 862  *  Here comes the stuff asynchronous to auditctl operations
 863  */
 864
 865 /* inode->inotify_mutex is locked */
 866 static void evict_chunk(struct audit_chunk *chunk)
 867 {
 868         struct audit_tree *owner;
 869         struct list_head *postponed = audit_killed_trees();
 870         int need_prune = 0;
 871         int n;
 872
 873         if (chunk->dead)
 874                 return;
 875
 876         chunk->dead = 1;
 877         mutex_lock(&audit_filter_mutex);
 878         spin_lock(&hash_lock);
 879         while (!list_empty(&chunk->trees)) {
 880                 owner = list_entry(chunk->trees.next,
 881                                    struct audit_tree, same_root);
 882                 owner->goner = 1;
 883                 owner->root = NULL;
 884                 list_del_init(&owner->same_root);
 885                 spin_unlock(&hash_lock);
 886                 if (!postponed) {
 887                         kill_rules(owner);
 888                         list_move(&owner->list, &prune_list);
 889                         need_prune = 1;
 890                 } else {
 891                         list_move(&owner->list, postponed);
 892                 }
 893                 spin_lock(&hash_lock);
 894         }
 895         list_del_rcu(&chunk->hash);
 896         for (n = 0; n < chunk->count; n++)
 897                 list_del_init(&chunk->owners[n].list);
 898         spin_unlock(&hash_lock);
 899         if (need_prune)
 900                 audit_schedule_prune();
 901         mutex_unlock(&audit_filter_mutex);
 902 }
 903
 904 static void handle_event(struct inotify_watch *watch, u32 wd, u32 mask,
 905                          u32 cookie, const char *dname, struct inode *inode)
 906 {
 907         struct audit_chunk *chunk = container_of(watch, struct audit_chunk, watch);
 908
 909         if (mask & IN_IGNORED) {
 910                 evict_chunk(chunk);
 911                 put_inotify_watch(watch);
 912         }
 913 }
 914
 915 static void destroy_watch(struct inotify_watch *watch)
 916 {
 917         struct audit_chunk *chunk = container_of(watch, struct audit_chunk, watch);
 918         call_rcu(&chunk->head, __put_chunk);
 919 }
 920
 921 static const struct inotify_operations rtree_inotify_ops = {
 922         .handle_event   = handle_event,
 923         .destroy_watch  = destroy_watch,
 924 };
 925
 926 static int __init audit_tree_init(void)
 927 {
 928         int i;
 929
 930         rtree_ih = inotify_init(&rtree_inotify_ops);
 931         if (IS_ERR(rtree_ih))
 932                 audit_panic("cannot initialize inotify handle for rectree watches");
 933
 934         for (i = 0; i < HASH_SIZE; i++)
 935                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
 936
 937         return 0;
 938 }
 939 __initcall(audit_tree_init);