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; j <= 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[j].list, &new->owners[i].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(&old->watch);
 376                         return 0;
 377                 }
 378         }
 379         spin_unlock(&hash_lock);
 380
 381         chunk = alloc_chunk(old->count + 1);
 382         if (!chunk) {
 383                 put_inotify_watch(&old->watch);
 384                 return -ENOMEM;
 385         }
 386
 387         mutex_lock(&inode->inotify_mutex);
 388         if (inotify_clone_watch(&old->watch, &chunk->watch) < 0) {
 389                 mutex_unlock(&inode->inotify_mutex);
 390                 free_chunk(chunk);
 391                 return -ENOSPC;
 392         }
 393         spin_lock(&hash_lock);
 394         if (tree->goner) {
 395                 spin_unlock(&hash_lock);
 396                 chunk->dead = 1;
 397                 inotify_evict_watch(&chunk->watch);
 398                 mutex_unlock(&inode->inotify_mutex);
 399                 put_inotify_watch(&chunk->watch);
 400                 return 0;
 401         }
 402         list_replace_init(&old->trees, &chunk->trees);
 403         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
 404                 struct audit_tree *s = old->owners[n].owner;
 405                 p->owner = s;
 406                 p->index = old->owners[n].index;
 407                 if (!s) /* result of fallback in untag */
 408                         continue;
 409                 get_tree(s);
 410                 list_replace_init(&old->owners[n].list, &p->list);
 411         }
 412         p->index = (chunk->count - 1) | (1U<<31);
 413         p->owner = tree;
 414         get_tree(tree);
 415         list_add(&p->list, &tree->chunks);
 416         list_replace_rcu(&old->hash, &chunk->hash);
 417         list_for_each_entry(owner, &chunk->trees, same_root)
 418                 owner->root = chunk;
 419         old->dead = 1;
 420         if (!tree->root) {
 421                 tree->root = chunk;
 422                 list_add(&tree->same_root, &chunk->trees);
 423         }
 424         spin_unlock(&hash_lock);
 425         inotify_evict_watch(&old->watch);
 426         mutex_unlock(&inode->inotify_mutex);
 427         put_inotify_watch(&old->watch); /* pair to inotify_find_watch */
 428         put_inotify_watch(&old->watch); /* and kill it */
 429         return 0;
 430 }
 431
 432 static void kill_rules(struct audit_tree *tree)
 433 {
 434         struct audit_krule *rule, *next;
 435         struct audit_entry *entry;
 436         struct audit_buffer *ab;
 437
 438         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
 439                 entry = container_of(rule, struct audit_entry, rule);
 440
 441                 list_del_init(&rule->rlist);
 442                 if (rule->tree) {
 443                         /* not a half-baked one */
 444                         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
 445                         audit_log_format(ab, "op=remove rule dir=");
 446                         audit_log_untrustedstring(ab, rule->tree->pathname);
 447                         if (rule->filterkey) {
 448                                 audit_log_format(ab, " key=");
 449                                 audit_log_untrustedstring(ab, rule->filterkey);
 450                         } else
 451                                 audit_log_format(ab, " key=(null)");
 452                         audit_log_format(ab, " list=%d res=1", rule->listnr);
 453                         audit_log_end(ab);
 454                         rule->tree = NULL;
 455                         list_del_rcu(&entry->list);
 456                         call_rcu(&entry->rcu, audit_free_rule_rcu);
 457                 }
 458         }
 459 }
 460
 461 /*
 462  * finish killing struct audit_tree
 463  */
 464 static void prune_one(struct audit_tree *victim)
 465 {
 466         spin_lock(&hash_lock);
 467         while (!list_empty(&victim->chunks)) {
 468                 struct node *p;
 469
 470                 p = list_entry(victim->chunks.next, struct node, list);
 471
 472                 untag_chunk(p);
 473         }
 474         spin_unlock(&hash_lock);
 475         put_tree(victim);
 476 }
 477
 478 /* trim the uncommitted chunks from tree */
 479
 480 static void trim_marked(struct audit_tree *tree)
 481 {
 482         struct list_head *p, *q;
 483         spin_lock(&hash_lock);
 484         if (tree->goner) {
 485                 spin_unlock(&hash_lock);
 486                 return;
 487         }
 488         /* reorder */
 489         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
 490                 struct node *node = list_entry(p, struct node, list);
 491                 q = p->next;
 492                 if (node->index & (1U<<31)) {
 493                         list_del_init(p);
 494                         list_add(p, &tree->chunks);
 495                 }
 496         }
 497
 498         while (!list_empty(&tree->chunks)) {
 499                 struct node *node;
 500
 501                 node = list_entry(tree->chunks.next, struct node, list);
 502
 503                 /* have we run out of marked? */
 504                 if (!(node->index & (1U<<31)))
 505                         break;
 506
 507                 untag_chunk(node);
 508         }
 509         if (!tree->root && !tree->goner) {
 510                 tree->goner = 1;
 511                 spin_unlock(&hash_lock);
 512                 mutex_lock(&audit_filter_mutex);
 513                 kill_rules(tree);
 514                 list_del_init(&tree->list);
 515                 mutex_unlock(&audit_filter_mutex);
 516                 prune_one(tree);
 517         } else {
 518                 spin_unlock(&hash_lock);
 519         }
 520 }
 521
 522 /* called with audit_filter_mutex */
 523 int audit_remove_tree_rule(struct audit_krule *rule)
 524 {
 525         struct audit_tree *tree;
 526         tree = rule->tree;
 527         if (tree) {
 528                 spin_lock(&hash_lock);
 529                 list_del_init(&rule->rlist);
 530                 if (list_empty(&tree->rules) && !tree->goner) {
 531                         tree->root = NULL;
 532                         list_del_init(&tree->same_root);
 533                         tree->goner = 1;
 534                         list_move(&tree->list, &prune_list);
 535                         rule->tree = NULL;
 536                         spin_unlock(&hash_lock);
 537                         audit_schedule_prune();
 538                         return 1;
 539                 }
 540                 rule->tree = NULL;
 541                 spin_unlock(&hash_lock);
 542                 return 1;
 543         }
 544         return 0;
 545 }
 546
 547 void audit_trim_trees(void)
 548 {
 549         struct list_head cursor;
 550
 551         mutex_lock(&audit_filter_mutex);
 552         list_add(&cursor, &tree_list);
 553         while (cursor.next != &tree_list) {
 554                 struct audit_tree *tree;
 555                 struct nameidata nd;
 556                 struct vfsmount *root_mnt;
 557                 struct node *node;
 558                 struct list_head list;
 559                 int err;
 560
 561                 tree = container_of(cursor.next, struct audit_tree, list);
 562                 get_tree(tree);
 563                 list_del(&cursor);
 564                 list_add(&cursor, &tree->list);
 565                 mutex_unlock(&audit_filter_mutex);
 566
 567                 err = path_lookup(tree->pathname, 0, &nd);
 568                 if (err)
 569                         goto skip_it;
 570
 571                 root_mnt = collect_mounts(nd.path.mnt, nd.path.dentry);
 572                 path_put(&nd.path);
 573                 if (!root_mnt)
 574                         goto skip_it;
 575
 576                 list_add_tail(&list, &root_mnt->mnt_list);
 577                 spin_lock(&hash_lock);
 578                 list_for_each_entry(node, &tree->chunks, list) {
 579                         struct audit_chunk *chunk = find_chunk(node);
 580                         struct inode *inode = chunk->watch.inode;
 581                         struct vfsmount *mnt;
 582                         node->index |= 1U<<31;
 583                         list_for_each_entry(mnt, &list, mnt_list) {
 584                                 if (mnt->mnt_root->d_inode == inode) {
 585                                         node->index &= ~(1U<<31);
 586                                         break;
 587                                 }
 588                         }
 589                 }
 590                 spin_unlock(&hash_lock);
 591                 trim_marked(tree);
 592                 put_tree(tree);
 593                 list_del_init(&list);
 594                 drop_collected_mounts(root_mnt);
 595 skip_it:
 596                 mutex_lock(&audit_filter_mutex);
 597         }
 598         list_del(&cursor);
 599         mutex_unlock(&audit_filter_mutex);
 600 }
 601
 602 static int is_under(struct vfsmount *mnt, struct dentry *dentry,
 603                     struct nameidata *nd)
 604 {
 605         if (mnt != nd->path.mnt) {
 606                 for (;;) {
 607                         if (mnt->mnt_parent == mnt)
 608                                 return 0;
 609                         if (mnt->mnt_parent == nd->path.mnt)
 610                                         break;
 611                         mnt = mnt->mnt_parent;
 612                 }
 613                 dentry = mnt->mnt_mountpoint;
 614         }
 615         return is_subdir(dentry, nd->path.dentry);
 616 }
 617
 618 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
 619 {
 620
 621         if (pathname[0] != '/' ||
 622             rule->listnr != AUDIT_FILTER_EXIT ||
 623             op & ~AUDIT_EQUAL ||
 624             rule->inode_f || rule->watch || rule->tree)
 625                 return -EINVAL;
 626         rule->tree = alloc_tree(pathname);
 627         if (!rule->tree)
 628                 return -ENOMEM;
 629         return 0;
 630 }
 631
 632 void audit_put_tree(struct audit_tree *tree)
 633 {
 634         put_tree(tree);
 635 }
 636
 637 /* called with audit_filter_mutex */
 638 int audit_add_tree_rule(struct audit_krule *rule)
 639 {
 640         struct audit_tree *seed = rule->tree, *tree;
 641         struct nameidata nd;
 642         struct vfsmount *mnt, *p;
 643         struct list_head list;
 644         int err;
 645
 646         list_for_each_entry(tree, &tree_list, list) {
 647                 if (!strcmp(seed->pathname, tree->pathname)) {
 648                         put_tree(seed);
 649                         rule->tree = tree;
 650                         list_add(&rule->rlist, &tree->rules);
 651                         return 0;
 652                 }
 653         }
 654         tree = seed;
 655         list_add(&tree->list, &tree_list);
 656         list_add(&rule->rlist, &tree->rules);
 657         /* do not set rule->tree yet */
 658         mutex_unlock(&audit_filter_mutex);
 659
 660         err = path_lookup(tree->pathname, 0, &nd);
 661         if (err)
 662                 goto Err;
 663         mnt = collect_mounts(nd.path.mnt, nd.path.dentry);
 664         path_put(&nd.path);
 665         if (!mnt) {
 666                 err = -ENOMEM;
 667                 goto Err;
 668         }
 669         list_add_tail(&list, &mnt->mnt_list);
 670
 671         get_tree(tree);
 672         list_for_each_entry(p, &list, mnt_list) {
 673                 err = tag_chunk(p->mnt_root->d_inode, tree);
 674                 if (err)
 675                         break;
 676         }
 677
 678         list_del(&list);
 679         drop_collected_mounts(mnt);
 680
 681         if (!err) {
 682                 struct node *node;
 683                 spin_lock(&hash_lock);
 684                 list_for_each_entry(node, &tree->chunks, list)
 685                         node->index &= ~(1U<<31);
 686                 spin_unlock(&hash_lock);
 687         } else {
 688                 trim_marked(tree);
 689                 goto Err;
 690         }
 691
 692         mutex_lock(&audit_filter_mutex);
 693         if (list_empty(&rule->rlist)) {
 694                 put_tree(tree);
 695                 return -ENOENT;
 696         }
 697         rule->tree = tree;
 698         put_tree(tree);
 699
 700         return 0;
 701 Err:
 702         mutex_lock(&audit_filter_mutex);
 703         list_del_init(&tree->list);
 704         list_del_init(&tree->rules);
 705         put_tree(tree);
 706         return err;
 707 }
 708
 709 int audit_tag_tree(char *old, char *new)
 710 {
 711         struct list_head cursor, barrier;
 712         int failed = 0;
 713         struct nameidata nd;
 714         struct vfsmount *tagged;
 715         struct list_head list;
 716         struct vfsmount *mnt;
 717         struct dentry *dentry;
 718         int err;
 719
 720         err = path_lookup(new, 0, &nd);
 721         if (err)
 722                 return err;
 723         tagged = collect_mounts(nd.path.mnt, nd.path.dentry);
 724         path_put(&nd.path);
 725         if (!tagged)
 726                 return -ENOMEM;
 727
 728         err = path_lookup(old, 0, &nd);
 729         if (err) {
 730                 drop_collected_mounts(tagged);
 731                 return err;
 732         }
 733         mnt = mntget(nd.path.mnt);
 734         dentry = dget(nd.path.dentry);
 735         path_put(&nd.path);
 736
 737         if (dentry == tagged->mnt_root && dentry == mnt->mnt_root)
 738                 follow_up(&mnt, &dentry);
 739
 740         list_add_tail(&list, &tagged->mnt_list);
 741
 742         mutex_lock(&audit_filter_mutex);
 743         list_add(&barrier, &tree_list);
 744         list_add(&cursor, &barrier);
 745
 746         while (cursor.next != &tree_list) {
 747                 struct audit_tree *tree;
 748                 struct vfsmount *p;
 749
 750                 tree = container_of(cursor.next, struct audit_tree, list);
 751                 get_tree(tree);
 752                 list_del(&cursor);
 753                 list_add(&cursor, &tree->list);
 754                 mutex_unlock(&audit_filter_mutex);
 755
 756                 err = path_lookup(tree->pathname, 0, &nd);
 757                 if (err) {
 758                         put_tree(tree);
 759                         mutex_lock(&audit_filter_mutex);
 760                         continue;
 761                 }
 762
 763                 spin_lock(&vfsmount_lock);
 764                 if (!is_under(mnt, dentry, &nd)) {
 765                         spin_unlock(&vfsmount_lock);
 766                         path_put(&nd.path);
 767                         put_tree(tree);
 768                         mutex_lock(&audit_filter_mutex);
 769                         continue;
 770                 }
 771                 spin_unlock(&vfsmount_lock);
 772                 path_put(&nd.path);
 773
 774                 list_for_each_entry(p, &list, mnt_list) {
 775                         failed = tag_chunk(p->mnt_root->d_inode, tree);
 776                         if (failed)
 777                                 break;
 778                 }
 779
 780                 if (failed) {
 781                         put_tree(tree);
 782                         mutex_lock(&audit_filter_mutex);
 783                         break;
 784                 }
 785
 786                 mutex_lock(&audit_filter_mutex);
 787                 spin_lock(&hash_lock);
 788                 if (!tree->goner) {
 789                         list_del(&tree->list);
 790                         list_add(&tree->list, &tree_list);
 791                 }
 792                 spin_unlock(&hash_lock);
 793                 put_tree(tree);
 794         }
 795
 796         while (barrier.prev != &tree_list) {
 797                 struct audit_tree *tree;
 798
 799                 tree = container_of(barrier.prev, struct audit_tree, list);
 800                 get_tree(tree);
 801                 list_del(&tree->list);
 802                 list_add(&tree->list, &barrier);
 803                 mutex_unlock(&audit_filter_mutex);
 804
 805                 if (!failed) {
 806                         struct node *node;
 807                         spin_lock(&hash_lock);
 808                         list_for_each_entry(node, &tree->chunks, list)
 809                                 node->index &= ~(1U<<31);
 810                         spin_unlock(&hash_lock);
 811                 } else {
 812                         trim_marked(tree);
 813                 }
 814
 815                 put_tree(tree);
 816                 mutex_lock(&audit_filter_mutex);
 817         }
 818         list_del(&barrier);
 819         list_del(&cursor);
 820         list_del(&list);
 821         mutex_unlock(&audit_filter_mutex);
 822         dput(dentry);
 823         mntput(mnt);
 824         drop_collected_mounts(tagged);
 825         return failed;
 826 }
 827
 828 /*
 829  * That gets run when evict_chunk() ends up needing to kill audit_tree.
 830  * Runs from a separate thread, with audit_cmd_mutex held.
 831  */
 832 void audit_prune_trees(void)
 833 {
 834         mutex_lock(&audit_filter_mutex);
 835
 836         while (!list_empty(&prune_list)) {
 837                 struct audit_tree *victim;
 838
 839                 victim = list_entry(prune_list.next, struct audit_tree, list);
 840                 list_del_init(&victim->list);
 841
 842                 mutex_unlock(&audit_filter_mutex);
 843
 844                 prune_one(victim);
 845
 846                 mutex_lock(&audit_filter_mutex);
 847         }
 848
 849         mutex_unlock(&audit_filter_mutex);
 850 }
 851
 852 /*
 853  *  Here comes the stuff asynchronous to auditctl operations
 854  */
 855
 856 /* inode->inotify_mutex is locked */
 857 static void evict_chunk(struct audit_chunk *chunk)
 858 {
 859         struct audit_tree *owner;
 860         int n;
 861
 862         if (chunk->dead)
 863                 return;
 864
 865         chunk->dead = 1;
 866         mutex_lock(&audit_filter_mutex);
 867         spin_lock(&hash_lock);
 868         while (!list_empty(&chunk->trees)) {
 869                 owner = list_entry(chunk->trees.next,
 870                                    struct audit_tree, same_root);
 871                 owner->goner = 1;
 872                 owner->root = NULL;
 873                 list_del_init(&owner->same_root);
 874                 spin_unlock(&hash_lock);
 875                 kill_rules(owner);
 876                 list_move(&owner->list, &prune_list);
 877                 audit_schedule_prune();
 878                 spin_lock(&hash_lock);
 879         }
 880         list_del_rcu(&chunk->hash);
 881         for (n = 0; n < chunk->count; n++)
 882                 list_del_init(&chunk->owners[n].list);
 883         spin_unlock(&hash_lock);
 884         mutex_unlock(&audit_filter_mutex);
 885 }
 886
 887 static void handle_event(struct inotify_watch *watch, u32 wd, u32 mask,
 888                          u32 cookie, const char *dname, struct inode *inode)
 889 {
 890         struct audit_chunk *chunk = container_of(watch, struct audit_chunk, watch);
 891
 892         if (mask & IN_IGNORED) {
 893                 evict_chunk(chunk);
 894                 put_inotify_watch(watch);
 895         }
 896 }
 897
 898 static void destroy_watch(struct inotify_watch *watch)
 899 {
 900         struct audit_chunk *chunk = container_of(watch, struct audit_chunk, watch);
 901         call_rcu(&chunk->head, __put_chunk);
 902 }
 903
 904 static const struct inotify_operations rtree_inotify_ops = {
 905         .handle_event   = handle_event,
 906         .destroy_watch  = destroy_watch,
 907 };
 908
 909 static int __init audit_tree_init(void)
 910 {
 911         int i;
 912
 913         rtree_ih = inotify_init(&rtree_inotify_ops);
 914         if (IS_ERR(rtree_ih))
 915                 audit_panic("cannot initialize inotify handle for rectree watches");
 916
 917         for (i = 0; i < HASH_SIZE; i++)
 918                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
 919
 920         return 0;
 921 }
 922 __initcall(audit_tree_init);