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                         if (entry->rule.exe)
 482                                 audit_remove_mark(entry->rule.exe);
 483                         rule->tree = NULL;
 484                         list_del_rcu(&entry->list);
 485                         list_del(&entry->rule.list);
 486                         call_rcu(&entry->rcu, audit_free_rule_rcu);
 487                 }
 488         }
 489 }
 490
 491 /*
 492  * finish killing struct audit_tree
 493  */
 494 static void prune_one(struct audit_tree *victim)
 495 {
 496         spin_lock(&hash_lock);
 497         while (!list_empty(&victim->chunks)) {
 498                 struct node *p;
 499
 500                 p = list_entry(victim->chunks.next, struct node, list);
 501
 502                 untag_chunk(p);
 503         }
 504         spin_unlock(&hash_lock);
 505         put_tree(victim);
 506 }
 507
 508 /* trim the uncommitted chunks from tree */
 509
 510 static void trim_marked(struct audit_tree *tree)
 511 {
 512         struct list_head *p, *q;
 513         spin_lock(&hash_lock);
 514         if (tree->goner) {
 515                 spin_unlock(&hash_lock);
 516                 return;
 517         }
 518         /* reorder */
 519         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
 520                 struct node *node = list_entry(p, struct node, list);
 521                 q = p->next;
 522                 if (node->index & (1U<<31)) {
 523                         list_del_init(p);
 524                         list_add(p, &tree->chunks);
 525                 }
 526         }
 527
 528         while (!list_empty(&tree->chunks)) {
 529                 struct node *node;
 530
 531                 node = list_entry(tree->chunks.next, struct node, list);
 532
 533                 /* have we run out of marked? */
 534                 if (!(node->index & (1U<<31)))
 535                         break;
 536
 537                 untag_chunk(node);
 538         }
 539         if (!tree->root && !tree->goner) {
 540                 tree->goner = 1;
 541                 spin_unlock(&hash_lock);
 542                 mutex_lock(&audit_filter_mutex);
 543                 kill_rules(tree);
 544                 list_del_init(&tree->list);
 545                 mutex_unlock(&audit_filter_mutex);
 546                 prune_one(tree);
 547         } else {
 548                 spin_unlock(&hash_lock);
 549         }
 550 }
 551
 552 static void audit_schedule_prune(void);
 553
 554 /* called with audit_filter_mutex */
 555 int audit_remove_tree_rule(struct audit_krule *rule)
 556 {
 557         struct audit_tree *tree;
 558         tree = rule->tree;
 559         if (tree) {
 560                 spin_lock(&hash_lock);
 561                 list_del_init(&rule->rlist);
 562                 if (list_empty(&tree->rules) && !tree->goner) {
 563                         tree->root = NULL;
 564                         list_del_init(&tree->same_root);
 565                         tree->goner = 1;
 566                         list_move(&tree->list, &prune_list);
 567                         rule->tree = NULL;
 568                         spin_unlock(&hash_lock);
 569                         audit_schedule_prune();
 570                         return 1;
 571                 }
 572                 rule->tree = NULL;
 573                 spin_unlock(&hash_lock);
 574                 return 1;
 575         }
 576         return 0;
 577 }
 578
 579 static int compare_root(struct vfsmount *mnt, void *arg)
 580 {
 581         return mnt->mnt_root->d_inode == arg;
 582 }
 583
 584 void audit_trim_trees(void)
 585 {
 586         struct list_head cursor;
 587
 588         mutex_lock(&audit_filter_mutex);
 589         list_add(&cursor, &tree_list);
 590         while (cursor.next != &tree_list) {
 591                 struct audit_tree *tree;
 592                 struct path path;
 593                 struct vfsmount *root_mnt;
 594                 struct node *node;
 595                 int err;
 596
 597                 tree = container_of(cursor.next, struct audit_tree, list);
 598                 get_tree(tree);
 599                 list_del(&cursor);
 600                 list_add(&cursor, &tree->list);
 601                 mutex_unlock(&audit_filter_mutex);
 602
 603                 err = kern_path(tree->pathname, 0, &path);
 604                 if (err)
 605                         goto skip_it;
 606
 607                 root_mnt = collect_mounts(&path);
 608                 path_put(&path);
 609                 if (IS_ERR(root_mnt))
 610                         goto skip_it;
 611
 612                 spin_lock(&hash_lock);
 613                 list_for_each_entry(node, &tree->chunks, list) {
 614                         struct audit_chunk *chunk = find_chunk(node);
 615                         /* this could be NULL if the watch is dying else where... */
 616                         struct inode *inode = chunk->mark.inode;
 617                         node->index |= 1U<<31;
 618                         if (iterate_mounts(compare_root, inode, root_mnt))
 619                                 node->index &= ~(1U<<31);
 620                 }
 621                 spin_unlock(&hash_lock);
 622                 trim_marked(tree);
 623                 drop_collected_mounts(root_mnt);
 624 skip_it:
 625                 put_tree(tree);
 626                 mutex_lock(&audit_filter_mutex);
 627         }
 628         list_del(&cursor);
 629         mutex_unlock(&audit_filter_mutex);
 630 }
 631
 632 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
 633 {
 634
 635         if (pathname[0] != '/' ||
 636             rule->listnr != AUDIT_FILTER_EXIT ||
 637             op != Audit_equal ||
 638             rule->inode_f || rule->watch || rule->tree)
 639                 return -EINVAL;
 640         rule->tree = alloc_tree(pathname);
 641         if (!rule->tree)
 642                 return -ENOMEM;
 643         return 0;
 644 }
 645
 646 void audit_put_tree(struct audit_tree *tree)
 647 {
 648         put_tree(tree);
 649 }
 650
 651 static int tag_mount(struct vfsmount *mnt, void *arg)
 652 {
 653         return tag_chunk(mnt->mnt_root->d_inode, arg);
 654 }
 655
 656 /* called with audit_filter_mutex */
 657 int audit_add_tree_rule(struct audit_krule *rule)
 658 {
 659         struct audit_tree *seed = rule->tree, *tree;
 660         struct path path;
 661         struct vfsmount *mnt;
 662         int err;
 663
 664         rule->tree = NULL;
 665         list_for_each_entry(tree, &tree_list, list) {
 666                 if (!strcmp(seed->pathname, tree->pathname)) {
 667                         put_tree(seed);
 668                         rule->tree = tree;
 669                         list_add(&rule->rlist, &tree->rules);
 670                         return 0;
 671                 }
 672         }
 673         tree = seed;
 674         list_add(&tree->list, &tree_list);
 675         list_add(&rule->rlist, &tree->rules);
 676         /* do not set rule->tree yet */
 677         mutex_unlock(&audit_filter_mutex);
 678
 679         err = kern_path(tree->pathname, 0, &path);
 680         if (err)
 681                 goto Err;
 682         mnt = collect_mounts(&path);
 683         path_put(&path);
 684         if (IS_ERR(mnt)) {
 685                 err = PTR_ERR(mnt);
 686                 goto Err;
 687         }
 688
 689         get_tree(tree);
 690         err = iterate_mounts(tag_mount, tree, mnt);
 691         drop_collected_mounts(mnt);
 692
 693         if (!err) {
 694                 struct node *node;
 695                 spin_lock(&hash_lock);
 696                 list_for_each_entry(node, &tree->chunks, list)
 697                         node->index &= ~(1U<<31);
 698                 spin_unlock(&hash_lock);
 699         } else {
 700                 trim_marked(tree);
 701                 goto Err;
 702         }
 703
 704         mutex_lock(&audit_filter_mutex);
 705         if (list_empty(&rule->rlist)) {
 706                 put_tree(tree);
 707                 return -ENOENT;
 708         }
 709         rule->tree = tree;
 710         put_tree(tree);
 711
 712         return 0;
 713 Err:
 714         mutex_lock(&audit_filter_mutex);
 715         list_del_init(&tree->list);
 716         list_del_init(&tree->rules);
 717         put_tree(tree);
 718         return err;
 719 }
 720
 721 int audit_tag_tree(char *old, char *new)
 722 {
 723         struct list_head cursor, barrier;
 724         int failed = 0;
 725         struct path path1, path2;
 726         struct vfsmount *tagged;
 727         int err;
 728
 729         err = kern_path(new, 0, &path2);
 730         if (err)
 731                 return err;
 732         tagged = collect_mounts(&path2);
 733         path_put(&path2);
 734         if (IS_ERR(tagged))
 735                 return PTR_ERR(tagged);
 736
 737         err = kern_path(old, 0, &path1);
 738         if (err) {
 739                 drop_collected_mounts(tagged);
 740                 return err;
 741         }
 742
 743         mutex_lock(&audit_filter_mutex);
 744         list_add(&barrier, &tree_list);
 745         list_add(&cursor, &barrier);
 746
 747         while (cursor.next != &tree_list) {
 748                 struct audit_tree *tree;
 749                 int good_one = 0;
 750
 751                 tree = container_of(cursor.next, struct audit_tree, list);
 752                 get_tree(tree);
 753                 list_del(&cursor);
 754                 list_add(&cursor, &tree->list);
 755                 mutex_unlock(&audit_filter_mutex);
 756
 757                 err = kern_path(tree->pathname, 0, &path2);
 758                 if (!err) {
 759                         good_one = path_is_under(&path1, &path2);
 760                         path_put(&path2);
 761                 }
 762
 763                 if (!good_one) {
 764                         put_tree(tree);
 765                         mutex_lock(&audit_filter_mutex);
 766                         continue;
 767                 }
 768
 769                 failed = iterate_mounts(tag_mount, tree, tagged);
 770                 if (failed) {
 771                         put_tree(tree);
 772                         mutex_lock(&audit_filter_mutex);
 773                         break;
 774                 }
 775
 776                 mutex_lock(&audit_filter_mutex);
 777                 spin_lock(&hash_lock);
 778                 if (!tree->goner) {
 779                         list_del(&tree->list);
 780                         list_add(&tree->list, &tree_list);
 781                 }
 782                 spin_unlock(&hash_lock);
 783                 put_tree(tree);
 784         }
 785
 786         while (barrier.prev != &tree_list) {
 787                 struct audit_tree *tree;
 788
 789                 tree = container_of(barrier.prev, struct audit_tree, list);
 790                 get_tree(tree);
 791                 list_del(&tree->list);
 792                 list_add(&tree->list, &barrier);
 793                 mutex_unlock(&audit_filter_mutex);
 794
 795                 if (!failed) {
 796                         struct node *node;
 797                         spin_lock(&hash_lock);
 798                         list_for_each_entry(node, &tree->chunks, list)
 799                                 node->index &= ~(1U<<31);
 800                         spin_unlock(&hash_lock);
 801                 } else {
 802                         trim_marked(tree);
 803                 }
 804
 805                 put_tree(tree);
 806                 mutex_lock(&audit_filter_mutex);
 807         }
 808         list_del(&barrier);
 809         list_del(&cursor);
 810         mutex_unlock(&audit_filter_mutex);
 811         path_put(&path1);
 812         drop_collected_mounts(tagged);
 813         return failed;
 814 }
 815
 816 /*
 817  * That gets run when evict_chunk() ends up needing to kill audit_tree.
 818  * Runs from a separate thread.
 819  */
 820 static int prune_tree_thread(void *unused)
 821 {
 822         mutex_lock(&audit_cmd_mutex);
 823         mutex_lock(&audit_filter_mutex);
 824
 825         while (!list_empty(&prune_list)) {
 826                 struct audit_tree *victim;
 827
 828                 victim = list_entry(prune_list.next, struct audit_tree, list);
 829                 list_del_init(&victim->list);
 830
 831                 mutex_unlock(&audit_filter_mutex);
 832
 833                 prune_one(victim);
 834
 835                 mutex_lock(&audit_filter_mutex);
 836         }
 837
 838         mutex_unlock(&audit_filter_mutex);
 839         mutex_unlock(&audit_cmd_mutex);
 840         return 0;
 841 }
 842
 843 static void audit_schedule_prune(void)
 844 {
 845         kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
 846 }
 847
 848 /*
 849  * ... and that one is done if evict_chunk() decides to delay until the end
 850  * of syscall.  Runs synchronously.
 851  */
 852 void audit_kill_trees(struct list_head *list)
 853 {
 854         mutex_lock(&audit_cmd_mutex);
 855         mutex_lock(&audit_filter_mutex);
 856
 857         while (!list_empty(list)) {
 858                 struct audit_tree *victim;
 859
 860                 victim = list_entry(list->next, struct audit_tree, list);
 861                 kill_rules(victim);
 862                 list_del_init(&victim->list);
 863
 864                 mutex_unlock(&audit_filter_mutex);
 865
 866                 prune_one(victim);
 867
 868                 mutex_lock(&audit_filter_mutex);
 869         }
 870
 871         mutex_unlock(&audit_filter_mutex);
 872         mutex_unlock(&audit_cmd_mutex);
 873 }
 874
 875 /*
 876  *  Here comes the stuff asynchronous to auditctl operations
 877  */
 878
 879 static void evict_chunk(struct audit_chunk *chunk)
 880 {
 881         struct audit_tree *owner;
 882         struct list_head *postponed = audit_killed_trees();
 883         int need_prune = 0;
 884         int n;
 885
 886         if (chunk->dead)
 887                 return;
 888
 889         chunk->dead = 1;
 890         mutex_lock(&audit_filter_mutex);
 891         spin_lock(&hash_lock);
 892         while (!list_empty(&chunk->trees)) {
 893                 owner = list_entry(chunk->trees.next,
 894                                    struct audit_tree, same_root);
 895                 owner->goner = 1;
 896                 owner->root = NULL;
 897                 list_del_init(&owner->same_root);
 898                 spin_unlock(&hash_lock);
 899                 if (!postponed) {
 900                         kill_rules(owner);
 901                         list_move(&owner->list, &prune_list);
 902                         need_prune = 1;
 903                 } else {
 904                         list_move(&owner->list, postponed);
 905                 }
 906                 spin_lock(&hash_lock);
 907         }
 908         list_del_rcu(&chunk->hash);
 909         for (n = 0; n < chunk->count; n++)
 910                 list_del_init(&chunk->owners[n].list);
 911         spin_unlock(&hash_lock);
 912         if (need_prune)
 913                 audit_schedule_prune();
 914         mutex_unlock(&audit_filter_mutex);
 915 }
 916
 917 static int audit_tree_handle_event(struct fsnotify_group *group,
 918                                    struct inode *to_tell,
 919                                    struct fsnotify_mark *inode_mark,
 920                                    struct fsnotify_mark *vfsmount_mark,
 921                                    u32 mask, void *data, int data_type,
 922                                    const unsigned char *file_name, u32 cookie)
 923 {
 924         return 0;
 925 }
 926
 927 static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
 928 {
 929         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
 930
 931         evict_chunk(chunk);
 932
 933         /*
 934          * We are guaranteed to have at least one reference to the mark from
 935          * either the inode or the caller of fsnotify_destroy_mark().
 936          */
 937         BUG_ON(atomic_read(&entry->refcnt) < 1);
 938 }
 939
 940 static const struct fsnotify_ops audit_tree_ops = {
 941         .handle_event = audit_tree_handle_event,
 942         .freeing_mark = audit_tree_freeing_mark,
 943 };
 944
 945 static int __init audit_tree_init(void)
 946 {
 947         int i;
 948
 949         audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
 950         if (IS_ERR(audit_tree_group))
 951                 audit_panic("cannot initialize fsnotify group for rectree watches");
 952
 953         for (i = 0; i < HASH_SIZE; i++)
 954                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
 955
 956         return 0;
 957 }
 958 __initcall(audit_tree_init);