kernel/audit_tree.c

   1 #include "audit.h"
   2 #include <linux/fsnotify_backend.h>
   3 #include <linux/namei.h>
   4 #include <linux/mount.h>
   5 #include <linux/kthread.h>
   6 #include <linux/slab.h>
   7
   8 struct audit_tree;
   9 struct audit_chunk;
  10
  11 struct audit_tree {
  12         atomic_t count;
  13         int goner;
  14         struct audit_chunk *root;
  15         struct list_head chunks;
  16         struct list_head rules;
  17         struct list_head list;
  18         struct list_head same_root;
  19         struct rcu_head head;
  20         char pathname[];
  21 };
  22
  23 struct audit_chunk {
  24         struct list_head hash;
  25         struct fsnotify_mark mark;
  26         struct list_head trees;         /* with root here */
  27         int dead;
  28         int count;
  29         atomic_long_t refs;
  30         struct rcu_head head;
  31         struct node {
  32                 struct list_head list;
  33                 struct audit_tree *owner;
  34                 unsigned index;         /* index; upper bit indicates 'will prune' */
  35         } owners[];
  36 };
  37
  38 static LIST_HEAD(tree_list);
  39 static LIST_HEAD(prune_list);
  40
  41 /*
  42  * One struct chunk is attached to each inode of interest.
  43  * We replace struct chunk on tagging/untagging.
  44  * Rules have pointer to struct audit_tree.
  45  * Rules have struct list_head rlist forming a list of rules over
  46  * the same tree.
  47  * References to struct chunk are collected at audit_inode{,_child}()
  48  * time and used in AUDIT_TREE rule matching.
  49  * These references are dropped at the same time we are calling
  50  * audit_free_names(), etc.
  51  *
  52  * Cyclic lists galore:
  53  * tree.chunks anchors chunk.owners[].list                      hash_lock
  54  * tree.rules anchors rule.rlist                                audit_filter_mutex
  55  * chunk.trees anchors tree.same_root                           hash_lock
  56  * chunk.hash is a hash with middle bits of watch.inode as
  57  * a hash function.                                             RCU, hash_lock
  58  *
  59  * tree is refcounted; one reference for "some rules on rules_list refer to
  60  * it", one for each chunk with pointer to it.
  61  *
  62  * chunk is refcounted by embedded fsnotify_mark + .refs (non-zero refcount
  63  * of watch contributes 1 to .refs).
  64  *
  65  * node.index allows to get from node.list to containing chunk.
  66  * MSB of that sucker is stolen to mark taggings that we might have to
  67  * revert - several operations have very unpleasant cleanup logics and
  68  * that makes a difference.  Some.
  69  */
  70
  71 static struct fsnotify_group *audit_tree_group;
  72
  73 static struct audit_tree *alloc_tree(const char *s)
  74 {
  75         struct audit_tree *tree;
  76
  77         tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
  78         if (tree) {
  79                 atomic_set(&tree->count, 1);
  80                 tree->goner = 0;
  81                 INIT_LIST_HEAD(&tree->chunks);
  82                 INIT_LIST_HEAD(&tree->rules);
  83                 INIT_LIST_HEAD(&tree->list);
  84                 INIT_LIST_HEAD(&tree->same_root);
  85                 tree->root = NULL;
  86                 strcpy(tree->pathname, s);
  87         }
  88         return tree;
  89 }
  90
  91 static inline void get_tree(struct audit_tree *tree)
  92 {
  93         atomic_inc(&tree->count);
  94 }
  95
  96 static inline void put_tree(struct audit_tree *tree)
  97 {
  98         if (atomic_dec_and_test(&tree->count))
  99                 kfree_rcu(tree, head);
 100 }
 101
 102 /* to avoid bringing the entire thing in audit.h */
 103 const char *audit_tree_path(struct audit_tree *tree)
 104 {
 105         return tree->pathname;
 106 }
 107
 108 static void free_chunk(struct audit_chunk *chunk)
 109 {
 110         int i;
 111
 112         for (i = 0; i < chunk->count; i++) {
 113                 if (chunk->owners[i].owner)
 114                         put_tree(chunk->owners[i].owner);
 115         }
 116         kfree(chunk);
 117 }
 118
 119 void audit_put_chunk(struct audit_chunk *chunk)
 120 {
 121         if (atomic_long_dec_and_test(&chunk->refs))
 122                 free_chunk(chunk);
 123 }
 124
 125 static void __put_chunk(struct rcu_head *rcu)
 126 {
 127         struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
 128         audit_put_chunk(chunk);
 129 }
 130
 131 static void audit_tree_destroy_watch(struct fsnotify_mark *entry)
 132 {
 133         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
 134         call_rcu(&chunk->head, __put_chunk);
 135 }
 136
 137 static struct audit_chunk *alloc_chunk(int count)
 138 {
 139         struct audit_chunk *chunk;
 140         size_t size;
 141         int i;
 142
 143         size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
 144         chunk = kzalloc(size, GFP_KERNEL);
 145         if (!chunk)
 146                 return NULL;
 147
 148         INIT_LIST_HEAD(&chunk->hash);
 149         INIT_LIST_HEAD(&chunk->trees);
 150         chunk->count = count;
 151         atomic_long_set(&chunk->refs, 1);
 152         for (i = 0; i < count; i++) {
 153                 INIT_LIST_HEAD(&chunk->owners[i].list);
 154                 chunk->owners[i].index = i;
 155         }
 156         fsnotify_init_mark(&chunk->mark, audit_tree_destroy_watch);
 157         chunk->mark.mask = FS_IN_IGNORED;
 158         return chunk;
 159 }
 160
 161 enum {HASH_SIZE = 128};
 162 static struct list_head chunk_hash_heads[HASH_SIZE];
 163 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
 164
 165 static inline struct list_head *chunk_hash(const struct inode *inode)
 166 {
 167         unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
 168         return chunk_hash_heads + n % HASH_SIZE;
 169 }
 170
 171 /* hash_lock & entry->lock is held by caller */
 172 static void insert_hash(struct audit_chunk *chunk)
 173 {
 174         struct fsnotify_mark *entry = &chunk->mark;
 175         struct list_head *list;
 176
 177         if (!entry->inode)
 178                 return;
 179         list = chunk_hash(entry->inode);
 180         list_add_rcu(&chunk->hash, list);
 181 }
 182
 183 /* called under rcu_read_lock */
 184 struct audit_chunk *audit_tree_lookup(const struct inode *inode)
 185 {
 186         struct list_head *list = chunk_hash(inode);
 187         struct audit_chunk *p;
 188
 189         list_for_each_entry_rcu(p, list, hash) {
 190                 /* mark.inode may have gone NULL, but who cares? */
 191                 if (p->mark.inode == inode) {
 192                         atomic_long_inc(&p->refs);
 193                         return p;
 194                 }
 195         }
 196         return NULL;
 197 }
 198
 199 int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
 200 {
 201         int n;
 202         for (n = 0; n < chunk->count; n++)
 203                 if (chunk->owners[n].owner == tree)
 204                         return 1;
 205         return 0;
 206 }
 207
 208 /* tagging and untagging inodes with trees */
 209
 210 static struct audit_chunk *find_chunk(struct node *p)
 211 {
 212         int index = p->index & ~(1U<<31);
 213         p -= index;
 214         return container_of(p, struct audit_chunk, owners[0]);
 215 }
 216
 217 static void untag_chunk(struct node *p)
 218 {
 219         struct audit_chunk *chunk = find_chunk(p);
 220         struct fsnotify_mark *entry = &chunk->mark;
 221         struct audit_chunk *new = NULL;
 222         struct audit_tree *owner;
 223         int size = chunk->count - 1;
 224         int i, j;
 225
 226         fsnotify_get_mark(entry);
 227
 228         spin_unlock(&hash_lock);
 229
 230         if (size)
 231                 new = alloc_chunk(size);
 232
 233         spin_lock(&entry->lock);
 234         if (chunk->dead || !entry->inode) {
 235                 spin_unlock(&entry->lock);
 236                 if (new)
 237                         free_chunk(new);
 238                 goto out;
 239         }
 240
 241         owner = p->owner;
 242
 243         if (!size) {
 244                 chunk->dead = 1;
 245                 spin_lock(&hash_lock);
 246                 list_del_init(&chunk->trees);
 247                 if (owner->root == chunk)
 248                         owner->root = NULL;
 249                 list_del_init(&p->list);
 250                 list_del_rcu(&chunk->hash);
 251                 spin_unlock(&hash_lock);
 252                 spin_unlock(&entry->lock);
 253                 fsnotify_destroy_mark(entry, audit_tree_group);
 254                 goto out;
 255         }
 256
 257         if (!new)
 258                 goto Fallback;
 259
 260         fsnotify_duplicate_mark(&new->mark, entry);
 261         if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.inode, NULL, 1)) {
 262                 fsnotify_put_mark(&new->mark);
 263                 goto Fallback;
 264         }
 265
 266         chunk->dead = 1;
 267         spin_lock(&hash_lock);
 268         list_replace_init(&chunk->trees, &new->trees);
 269         if (owner->root == chunk) {
 270                 list_del_init(&owner->same_root);
 271                 owner->root = NULL;
 272         }
 273
 274         for (i = j = 0; j <= size; i++, j++) {
 275                 struct audit_tree *s;
 276                 if (&chunk->owners[j] == p) {
 277                         list_del_init(&p->list);
 278                         i--;
 279                         continue;
 280                 }
 281                 s = chunk->owners[j].owner;
 282                 new->owners[i].owner = s;
 283                 new->owners[i].index = chunk->owners[j].index - j + i;
 284                 if (!s) /* result of earlier fallback */
 285                         continue;
 286                 get_tree(s);
 287                 list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
 288         }
 289
 290         list_replace_rcu(&chunk->hash, &new->hash);
 291         list_for_each_entry(owner, &new->trees, same_root)
 292                 owner->root = new;
 293         spin_unlock(&hash_lock);
 294         spin_unlock(&entry->lock);
 295         fsnotify_destroy_mark(entry, audit_tree_group);
 296         fsnotify_put_mark(&new->mark);  /* drop initial reference */
 297         goto out;
 298
 299 Fallback:
 300         // do the best we can
 301         spin_lock(&hash_lock);
 302         if (owner->root == chunk) {
 303                 list_del_init(&owner->same_root);
 304                 owner->root = NULL;
 305         }
 306         list_del_init(&p->list);
 307         p->owner = NULL;
 308         put_tree(owner);
 309         spin_unlock(&hash_lock);
 310         spin_unlock(&entry->lock);
 311 out:
 312         fsnotify_put_mark(entry);
 313         spin_lock(&hash_lock);
 314 }
 315
 316 static int create_chunk(struct inode *inode, struct audit_tree *tree)
 317 {
 318         struct fsnotify_mark *entry;
 319         struct audit_chunk *chunk = alloc_chunk(1);
 320         if (!chunk)
 321                 return -ENOMEM;
 322
 323         entry = &chunk->mark;
 324         if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) {
 325                 fsnotify_put_mark(entry);
 326                 return -ENOSPC;
 327         }
 328
 329         spin_lock(&entry->lock);
 330         spin_lock(&hash_lock);
 331         if (tree->goner) {
 332                 spin_unlock(&hash_lock);
 333                 chunk->dead = 1;
 334                 spin_unlock(&entry->lock);
 335                 fsnotify_destroy_mark(entry, audit_tree_group);
 336                 fsnotify_put_mark(entry);
 337                 return 0;
 338         }
 339         chunk->owners[0].index = (1U << 31);
 340         chunk->owners[0].owner = tree;
 341         get_tree(tree);
 342         list_add(&chunk->owners[0].list, &tree->chunks);
 343         if (!tree->root) {
 344                 tree->root = chunk;
 345                 list_add(&tree->same_root, &chunk->trees);
 346         }
 347         insert_hash(chunk);
 348         spin_unlock(&hash_lock);
 349         spin_unlock(&entry->lock);
 350         fsnotify_put_mark(entry);       /* drop initial reference */
 351         return 0;
 352 }
 353
 354 /* the first tagged inode becomes root of tree */
 355 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
 356 {
 357         struct fsnotify_mark *old_entry, *chunk_entry;
 358         struct audit_tree *owner;
 359         struct audit_chunk *chunk, *old;
 360         struct node *p;
 361         int n;
 362
 363         old_entry = fsnotify_find_inode_mark(audit_tree_group, inode);
 364         if (!old_entry)
 365                 return create_chunk(inode, tree);
 366
 367         old = container_of(old_entry, struct audit_chunk, mark);
 368
 369         /* are we already there? */
 370         spin_lock(&hash_lock);
 371         for (n = 0; n < old->count; n++) {
 372                 if (old->owners[n].owner == tree) {
 373                         spin_unlock(&hash_lock);
 374                         fsnotify_put_mark(old_entry);
 375                         return 0;
 376                 }
 377         }
 378         spin_unlock(&hash_lock);
 379
 380         chunk = alloc_chunk(old->count + 1);
 381         if (!chunk) {
 382                 fsnotify_put_mark(old_entry);
 383                 return -ENOMEM;
 384         }
 385
 386         chunk_entry = &chunk->mark;
 387
 388         spin_lock(&old_entry->lock);
 389         if (!old_entry->inode) {
 390                 /* old_entry is being shot, lets just lie */
 391                 spin_unlock(&old_entry->lock);
 392                 fsnotify_put_mark(old_entry);
 393                 free_chunk(chunk);
 394                 return -ENOENT;
 395         }
 396
 397         fsnotify_duplicate_mark(chunk_entry, old_entry);
 398         if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->inode, NULL, 1)) {
 399                 spin_unlock(&old_entry->lock);
 400                 fsnotify_put_mark(chunk_entry);
 401                 fsnotify_put_mark(old_entry);
 402                 return -ENOSPC;
 403         }
 404
 405         /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
 406         spin_lock(&chunk_entry->lock);
 407         spin_lock(&hash_lock);
 408
 409         /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
 410         if (tree->goner) {
 411                 spin_unlock(&hash_lock);
 412                 chunk->dead = 1;
 413                 spin_unlock(&chunk_entry->lock);
 414                 spin_unlock(&old_entry->lock);
 415
 416                 fsnotify_destroy_mark(chunk_entry, audit_tree_group);
 417
 418                 fsnotify_put_mark(chunk_entry);
 419                 fsnotify_put_mark(old_entry);
 420                 return 0;
 421         }
 422         list_replace_init(&old->trees, &chunk->trees);
 423         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
 424                 struct audit_tree *s = old->owners[n].owner;
 425                 p->owner = s;
 426                 p->index = old->owners[n].index;
 427                 if (!s) /* result of fallback in untag */
 428                         continue;
 429                 get_tree(s);
 430                 list_replace_init(&old->owners[n].list, &p->list);
 431         }
 432         p->index = (chunk->count - 1) | (1U<<31);
 433         p->owner = tree;
 434         get_tree(tree);
 435         list_add(&p->list, &tree->chunks);
 436         list_replace_rcu(&old->hash, &chunk->hash);
 437         list_for_each_entry(owner, &chunk->trees, same_root)
 438                 owner->root = chunk;
 439         old->dead = 1;
 440         if (!tree->root) {
 441                 tree->root = chunk;
 442                 list_add(&tree->same_root, &chunk->trees);
 443         }
 444         spin_unlock(&hash_lock);
 445         spin_unlock(&chunk_entry->lock);
 446         spin_unlock(&old_entry->lock);
 447         fsnotify_destroy_mark(old_entry, audit_tree_group);
 448         fsnotify_put_mark(chunk_entry); /* drop initial reference */
 449         fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
 450         return 0;
 451 }
 452
 453 static void audit_tree_log_remove_rule(struct audit_krule *rule)
 454 {
 455         struct audit_buffer *ab;
 456
 457         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
 458         if (unlikely(!ab))
 459                 return;
 460         audit_log_format(ab, "op=");
 461         audit_log_string(ab, "remove_rule");
 462         audit_log_format(ab, " dir=");
 463         audit_log_untrustedstring(ab, rule->tree->pathname);
 464         audit_log_key(ab, rule->filterkey);
 465         audit_log_format(ab, " list=%d res=1", rule->listnr);
 466         audit_log_end(ab);
 467 }
 468
 469 static void kill_rules(struct audit_tree *tree)
 470 {
 471         struct audit_krule *rule, *next;
 472         struct audit_entry *entry;
 473
 474         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
 475                 entry = container_of(rule, struct audit_entry, rule);
 476
 477                 list_del_init(&rule->rlist);
 478                 if (rule->tree) {
 479                         /* not a half-baked one */
 480                         audit_tree_log_remove_rule(rule);
 481                         rule->tree = NULL;
 482                         list_del_rcu(&entry->list);
 483                         list_del(&entry->rule.list);
 484                         call_rcu(&entry->rcu, audit_free_rule_rcu);
 485                 }
 486         }
 487 }
 488
 489 /*
 490  * finish killing struct audit_tree
 491  */
 492 static void prune_one(struct audit_tree *victim)
 493 {
 494         spin_lock(&hash_lock);
 495         while (!list_empty(&victim->chunks)) {
 496                 struct node *p;
 497
 498                 p = list_entry(victim->chunks.next, struct node, list);
 499
 500                 untag_chunk(p);
 501         }
 502         spin_unlock(&hash_lock);
 503         put_tree(victim);
 504 }
 505
 506 /* trim the uncommitted chunks from tree */
 507
 508 static void trim_marked(struct audit_tree *tree)
 509 {
 510         struct list_head *p, *q;
 511         spin_lock(&hash_lock);
 512         if (tree->goner) {
 513                 spin_unlock(&hash_lock);
 514                 return;
 515         }
 516         /* reorder */
 517         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
 518                 struct node *node = list_entry(p, struct node, list);
 519                 q = p->next;
 520                 if (node->index & (1U<<31)) {
 521                         list_del_init(p);
 522                         list_add(p, &tree->chunks);
 523                 }
 524         }
 525
 526         while (!list_empty(&tree->chunks)) {
 527                 struct node *node;
 528
 529                 node = list_entry(tree->chunks.next, struct node, list);
 530
 531                 /* have we run out of marked? */
 532                 if (!(node->index & (1U<<31)))
 533                         break;
 534
 535                 untag_chunk(node);
 536         }
 537         if (!tree->root && !tree->goner) {
 538                 tree->goner = 1;
 539                 spin_unlock(&hash_lock);
 540                 mutex_lock(&audit_filter_mutex);
 541                 kill_rules(tree);
 542                 list_del_init(&tree->list);
 543                 mutex_unlock(&audit_filter_mutex);
 544                 prune_one(tree);
 545         } else {
 546                 spin_unlock(&hash_lock);
 547         }
 548 }
 549
 550 static void audit_schedule_prune(void);
 551
 552 /* called with audit_filter_mutex */
 553 int audit_remove_tree_rule(struct audit_krule *rule)
 554 {
 555         struct audit_tree *tree;
 556         tree = rule->tree;
 557         if (tree) {
 558                 spin_lock(&hash_lock);
 559                 list_del_init(&rule->rlist);
 560                 if (list_empty(&tree->rules) && !tree->goner) {
 561                         tree->root = NULL;
 562                         list_del_init(&tree->same_root);
 563                         tree->goner = 1;
 564                         list_move(&tree->list, &prune_list);
 565                         rule->tree = NULL;
 566                         spin_unlock(&hash_lock);
 567                         audit_schedule_prune();
 568                         return 1;
 569                 }
 570                 rule->tree = NULL;
 571                 spin_unlock(&hash_lock);
 572                 return 1;
 573         }
 574         return 0;
 575 }
 576
 577 static int compare_root(struct vfsmount *mnt, void *arg)
 578 {
 579         return mnt->mnt_root->d_inode == arg;
 580 }
 581
 582 void audit_trim_trees(void)
 583 {
 584         struct list_head cursor;
 585
 586         mutex_lock(&audit_filter_mutex);
 587         list_add(&cursor, &tree_list);
 588         while (cursor.next != &tree_list) {
 589                 struct audit_tree *tree;
 590                 struct path path;
 591                 struct vfsmount *root_mnt;
 592                 struct node *node;
 593                 int err;
 594
 595                 tree = container_of(cursor.next, struct audit_tree, list);
 596                 get_tree(tree);
 597                 list_del(&cursor);
 598                 list_add(&cursor, &tree->list);
 599                 mutex_unlock(&audit_filter_mutex);
 600
 601                 err = kern_path(tree->pathname, 0, &path);
 602                 if (err)
 603                         goto skip_it;
 604
 605                 root_mnt = collect_mounts(&path);
 606                 path_put(&path);
 607                 if (IS_ERR(root_mnt))
 608                         goto skip_it;
 609
 610                 spin_lock(&hash_lock);
 611                 list_for_each_entry(node, &tree->chunks, list) {
 612                         struct audit_chunk *chunk = find_chunk(node);
 613                         /* this could be NULL if the watch is dying else where... */
 614                         struct inode *inode = chunk->mark.inode;
 615                         node->index |= 1U<<31;
 616                         if (iterate_mounts(compare_root, inode, root_mnt))
 617                                 node->index &= ~(1U<<31);
 618                 }
 619                 spin_unlock(&hash_lock);
 620                 trim_marked(tree);
 621                 drop_collected_mounts(root_mnt);
 622 skip_it:
 623                 put_tree(tree);
 624                 mutex_lock(&audit_filter_mutex);
 625         }
 626         list_del(&cursor);
 627         mutex_unlock(&audit_filter_mutex);
 628 }
 629
 630 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
 631 {
 632
 633         if (pathname[0] != '/' ||
 634             rule->listnr != AUDIT_FILTER_EXIT ||
 635             op != Audit_equal ||
 636             rule->inode_f || rule->watch || rule->tree)
 637                 return -EINVAL;
 638         rule->tree = alloc_tree(pathname);
 639         if (!rule->tree)
 640                 return -ENOMEM;
 641         return 0;
 642 }
 643
 644 void audit_put_tree(struct audit_tree *tree)
 645 {
 646         put_tree(tree);
 647 }
 648
 649 static int tag_mount(struct vfsmount *mnt, void *arg)
 650 {
 651         return tag_chunk(mnt->mnt_root->d_inode, arg);
 652 }
 653
 654 /* called with audit_filter_mutex */
 655 int audit_add_tree_rule(struct audit_krule *rule)
 656 {
 657         struct audit_tree *seed = rule->tree, *tree;
 658         struct path path;
 659         struct vfsmount *mnt;
 660         int err;
 661
 662         rule->tree = NULL;
 663         list_for_each_entry(tree, &tree_list, list) {
 664                 if (!strcmp(seed->pathname, tree->pathname)) {
 665                         put_tree(seed);
 666                         rule->tree = tree;
 667                         list_add(&rule->rlist, &tree->rules);
 668                         return 0;
 669                 }
 670         }
 671         tree = seed;
 672         list_add(&tree->list, &tree_list);
 673         list_add(&rule->rlist, &tree->rules);
 674         /* do not set rule->tree yet */
 675         mutex_unlock(&audit_filter_mutex);
 676
 677         err = kern_path(tree->pathname, 0, &path);
 678         if (err)
 679                 goto Err;
 680         mnt = collect_mounts(&path);
 681         path_put(&path);
 682         if (IS_ERR(mnt)) {
 683                 err = PTR_ERR(mnt);
 684                 goto Err;
 685         }
 686
 687         get_tree(tree);
 688         err = iterate_mounts(tag_mount, tree, mnt);
 689         drop_collected_mounts(mnt);
 690
 691         if (!err) {
 692                 struct node *node;
 693                 spin_lock(&hash_lock);
 694                 list_for_each_entry(node, &tree->chunks, list)
 695                         node->index &= ~(1U<<31);
 696                 spin_unlock(&hash_lock);
 697         } else {
 698                 trim_marked(tree);
 699                 goto Err;
 700         }
 701
 702         mutex_lock(&audit_filter_mutex);
 703         if (list_empty(&rule->rlist)) {
 704                 put_tree(tree);
 705                 return -ENOENT;
 706         }
 707         rule->tree = tree;
 708         put_tree(tree);
 709
 710         return 0;
 711 Err:
 712         mutex_lock(&audit_filter_mutex);
 713         list_del_init(&tree->list);
 714         list_del_init(&tree->rules);
 715         put_tree(tree);
 716         return err;
 717 }
 718
 719 int audit_tag_tree(char *old, char *new)
 720 {
 721         struct list_head cursor, barrier;
 722         int failed = 0;
 723         struct path path1, path2;
 724         struct vfsmount *tagged;
 725         int err;
 726
 727         err = kern_path(new, 0, &path2);
 728         if (err)
 729                 return err;
 730         tagged = collect_mounts(&path2);
 731         path_put(&path2);
 732         if (IS_ERR(tagged))
 733                 return PTR_ERR(tagged);
 734
 735         err = kern_path(old, 0, &path1);
 736         if (err) {
 737                 drop_collected_mounts(tagged);
 738                 return err;
 739         }
 740
 741         mutex_lock(&audit_filter_mutex);
 742         list_add(&barrier, &tree_list);
 743         list_add(&cursor, &barrier);
 744
 745         while (cursor.next != &tree_list) {
 746                 struct audit_tree *tree;
 747                 int good_one = 0;
 748
 749                 tree = container_of(cursor.next, struct audit_tree, list);
 750                 get_tree(tree);
 751                 list_del(&cursor);
 752                 list_add(&cursor, &tree->list);
 753                 mutex_unlock(&audit_filter_mutex);
 754
 755                 err = kern_path(tree->pathname, 0, &path2);
 756                 if (!err) {
 757                         good_one = path_is_under(&path1, &path2);
 758                         path_put(&path2);
 759                 }
 760
 761                 if (!good_one) {
 762                         put_tree(tree);
 763                         mutex_lock(&audit_filter_mutex);
 764                         continue;
 765                 }
 766
 767                 failed = iterate_mounts(tag_mount, tree, tagged);
 768                 if (failed) {
 769                         put_tree(tree);
 770                         mutex_lock(&audit_filter_mutex);
 771                         break;
 772                 }
 773
 774                 mutex_lock(&audit_filter_mutex);
 775                 spin_lock(&hash_lock);
 776                 if (!tree->goner) {
 777                         list_del(&tree->list);
 778                         list_add(&tree->list, &tree_list);
 779                 }
 780                 spin_unlock(&hash_lock);
 781                 put_tree(tree);
 782         }
 783
 784         while (barrier.prev != &tree_list) {
 785                 struct audit_tree *tree;
 786
 787                 tree = container_of(barrier.prev, struct audit_tree, list);
 788                 get_tree(tree);
 789                 list_del(&tree->list);
 790                 list_add(&tree->list, &barrier);
 791                 mutex_unlock(&audit_filter_mutex);
 792
 793                 if (!failed) {
 794                         struct node *node;
 795                         spin_lock(&hash_lock);
 796                         list_for_each_entry(node, &tree->chunks, list)
 797                                 node->index &= ~(1U<<31);
 798                         spin_unlock(&hash_lock);
 799                 } else {
 800                         trim_marked(tree);
 801                 }
 802
 803                 put_tree(tree);
 804                 mutex_lock(&audit_filter_mutex);
 805         }
 806         list_del(&barrier);
 807         list_del(&cursor);
 808         mutex_unlock(&audit_filter_mutex);
 809         path_put(&path1);
 810         drop_collected_mounts(tagged);
 811         return failed;
 812 }
 813
 814 /*
 815  * That gets run when evict_chunk() ends up needing to kill audit_tree.
 816  * Runs from a separate thread.
 817  */
 818 static int prune_tree_thread(void *unused)
 819 {
 820         mutex_lock(&audit_cmd_mutex);
 821         mutex_lock(&audit_filter_mutex);
 822
 823         while (!list_empty(&prune_list)) {
 824                 struct audit_tree *victim;
 825
 826                 victim = list_entry(prune_list.next, struct audit_tree, list);
 827                 list_del_init(&victim->list);
 828
 829                 mutex_unlock(&audit_filter_mutex);
 830
 831                 prune_one(victim);
 832
 833                 mutex_lock(&audit_filter_mutex);
 834         }
 835
 836         mutex_unlock(&audit_filter_mutex);
 837         mutex_unlock(&audit_cmd_mutex);
 838         return 0;
 839 }
 840
 841 static void audit_schedule_prune(void)
 842 {
 843         kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
 844 }
 845
 846 /*
 847  * ... and that one is done if evict_chunk() decides to delay until the end
 848  * of syscall.  Runs synchronously.
 849  */
 850 void audit_kill_trees(struct list_head *list)
 851 {
 852         mutex_lock(&audit_cmd_mutex);
 853         mutex_lock(&audit_filter_mutex);
 854
 855         while (!list_empty(list)) {
 856                 struct audit_tree *victim;
 857
 858                 victim = list_entry(list->next, struct audit_tree, list);
 859                 kill_rules(victim);
 860                 list_del_init(&victim->list);
 861
 862                 mutex_unlock(&audit_filter_mutex);
 863
 864                 prune_one(victim);
 865
 866                 mutex_lock(&audit_filter_mutex);
 867         }
 868
 869         mutex_unlock(&audit_filter_mutex);
 870         mutex_unlock(&audit_cmd_mutex);
 871 }
 872
 873 /*
 874  *  Here comes the stuff asynchronous to auditctl operations
 875  */
 876
 877 static void evict_chunk(struct audit_chunk *chunk)
 878 {
 879         struct audit_tree *owner;
 880         struct list_head *postponed = audit_killed_trees();
 881         int need_prune = 0;
 882         int n;
 883
 884         if (chunk->dead)
 885                 return;
 886
 887         chunk->dead = 1;
 888         mutex_lock(&audit_filter_mutex);
 889         spin_lock(&hash_lock);
 890         while (!list_empty(&chunk->trees)) {
 891                 owner = list_entry(chunk->trees.next,
 892                                    struct audit_tree, same_root);
 893                 owner->goner = 1;
 894                 owner->root = NULL;
 895                 list_del_init(&owner->same_root);
 896                 spin_unlock(&hash_lock);
 897                 if (!postponed) {
 898                         kill_rules(owner);
 899                         list_move(&owner->list, &prune_list);
 900                         need_prune = 1;
 901                 } else {
 902                         list_move(&owner->list, postponed);
 903                 }
 904                 spin_lock(&hash_lock);
 905         }
 906         list_del_rcu(&chunk->hash);
 907         for (n = 0; n < chunk->count; n++)
 908                 list_del_init(&chunk->owners[n].list);
 909         spin_unlock(&hash_lock);
 910         if (need_prune)
 911                 audit_schedule_prune();
 912         mutex_unlock(&audit_filter_mutex);
 913 }
 914
 915 static int audit_tree_handle_event(struct fsnotify_group *group,
 916                                    struct inode *to_tell,
 917                                    struct fsnotify_mark *inode_mark,
 918                                    struct fsnotify_mark *vfsmount_mark,
 919                                    u32 mask, void *data, int data_type,
 920                                    const unsigned char *file_name, u32 cookie)
 921 {
 922         return 0;
 923 }
 924
 925 static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
 926 {
 927         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
 928
 929         evict_chunk(chunk);
 930
 931         /*
 932          * We are guaranteed to have at least one reference to the mark from
 933          * either the inode or the caller of fsnotify_destroy_mark().
 934          */
 935         BUG_ON(atomic_read(&entry->refcnt) < 1);
 936 }
 937
 938 static const struct fsnotify_ops audit_tree_ops = {
 939         .handle_event = audit_tree_handle_event,
 940         .freeing_mark = audit_tree_freeing_mark,
 941 };
 942
 943 static int __init audit_tree_init(void)
 944 {
 945         int i;
 946
 947         audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
 948         if (IS_ERR(audit_tree_group))
 949                 audit_panic("cannot initialize fsnotify group for rectree watches");
 950
 951         for (i = 0; i < HASH_SIZE; i++)
 952                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
 953
 954         return 0;
 955 }
 956 __initcall(audit_tree_init);