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         return chunk;
 158 }
 159
 160 enum {HASH_SIZE = 128};
 161 static struct list_head chunk_hash_heads[HASH_SIZE];
 162 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
 163
 164 static inline struct list_head *chunk_hash(const struct inode *inode)
 165 {
 166         unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
 167         return chunk_hash_heads + n % HASH_SIZE;
 168 }
 169
 170 /* hash_lock & entry->lock is held by caller */
 171 static void insert_hash(struct audit_chunk *chunk)
 172 {
 173         struct fsnotify_mark *entry = &chunk->mark;
 174         struct list_head *list;
 175
 176         if (!entry->i.inode)
 177                 return;
 178         list = chunk_hash(entry->i.inode);
 179         list_add_rcu(&chunk->hash, list);
 180 }
 181
 182 /* called under rcu_read_lock */
 183 struct audit_chunk *audit_tree_lookup(const struct inode *inode)
 184 {
 185         struct list_head *list = chunk_hash(inode);
 186         struct audit_chunk *p;
 187
 188         list_for_each_entry_rcu(p, list, hash) {
 189                 /* mark.inode may have gone NULL, but who cares? */
 190                 if (p->mark.i.inode == inode) {
 191                         atomic_long_inc(&p->refs);
 192                         return p;
 193                 }
 194         }
 195         return NULL;
 196 }
 197
 198 int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
 199 {
 200         int n;
 201         for (n = 0; n < chunk->count; n++)
 202                 if (chunk->owners[n].owner == tree)
 203                         return 1;
 204         return 0;
 205 }
 206
 207 /* tagging and untagging inodes with trees */
 208
 209 static struct audit_chunk *find_chunk(struct node *p)
 210 {
 211         int index = p->index & ~(1U<<31);
 212         p -= index;
 213         return container_of(p, struct audit_chunk, owners[0]);
 214 }
 215
 216 static void untag_chunk(struct node *p)
 217 {
 218         struct audit_chunk *chunk = find_chunk(p);
 219         struct fsnotify_mark *entry = &chunk->mark;
 220         struct audit_chunk *new = NULL;
 221         struct audit_tree *owner;
 222         int size = chunk->count - 1;
 223         int i, j;
 224
 225         fsnotify_get_mark(entry);
 226
 227         spin_unlock(&hash_lock);
 228
 229         if (size)
 230                 new = alloc_chunk(size);
 231
 232         spin_lock(&entry->lock);
 233         if (chunk->dead || !entry->i.inode) {
 234                 spin_unlock(&entry->lock);
 235                 if (new)
 236                         free_chunk(new);
 237                 goto out;
 238         }
 239
 240         owner = p->owner;
 241
 242         if (!size) {
 243                 chunk->dead = 1;
 244                 spin_lock(&hash_lock);
 245                 list_del_init(&chunk->trees);
 246                 if (owner->root == chunk)
 247                         owner->root = NULL;
 248                 list_del_init(&p->list);
 249                 list_del_rcu(&chunk->hash);
 250                 spin_unlock(&hash_lock);
 251                 spin_unlock(&entry->lock);
 252                 fsnotify_destroy_mark(entry, audit_tree_group);
 253                 goto out;
 254         }
 255
 256         if (!new)
 257                 goto Fallback;
 258
 259         fsnotify_duplicate_mark(&new->mark, entry);
 260         if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.i.inode, NULL, 1)) {
 261                 fsnotify_put_mark(&new->mark);
 262                 goto Fallback;
 263         }
 264
 265         chunk->dead = 1;
 266         spin_lock(&hash_lock);
 267         list_replace_init(&chunk->trees, &new->trees);
 268         if (owner->root == chunk) {
 269                 list_del_init(&owner->same_root);
 270                 owner->root = NULL;
 271         }
 272
 273         for (i = j = 0; j <= size; i++, j++) {
 274                 struct audit_tree *s;
 275                 if (&chunk->owners[j] == p) {
 276                         list_del_init(&p->list);
 277                         i--;
 278                         continue;
 279                 }
 280                 s = chunk->owners[j].owner;
 281                 new->owners[i].owner = s;
 282                 new->owners[i].index = chunk->owners[j].index - j + i;
 283                 if (!s) /* result of earlier fallback */
 284                         continue;
 285                 get_tree(s);
 286                 list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
 287         }
 288
 289         list_replace_rcu(&chunk->hash, &new->hash);
 290         list_for_each_entry(owner, &new->trees, same_root)
 291                 owner->root = new;
 292         spin_unlock(&hash_lock);
 293         spin_unlock(&entry->lock);
 294         fsnotify_destroy_mark(entry, audit_tree_group);
 295         fsnotify_put_mark(&new->mark);  /* drop initial reference */
 296         goto out;
 297
 298 Fallback:
 299         // do the best we can
 300         spin_lock(&hash_lock);
 301         if (owner->root == chunk) {
 302                 list_del_init(&owner->same_root);
 303                 owner->root = NULL;
 304         }
 305         list_del_init(&p->list);
 306         p->owner = NULL;
 307         put_tree(owner);
 308         spin_unlock(&hash_lock);
 309         spin_unlock(&entry->lock);
 310 out:
 311         fsnotify_put_mark(entry);
 312         spin_lock(&hash_lock);
 313 }
 314
 315 static int create_chunk(struct inode *inode, struct audit_tree *tree)
 316 {
 317         struct fsnotify_mark *entry;
 318         struct audit_chunk *chunk = alloc_chunk(1);
 319         if (!chunk)
 320                 return -ENOMEM;
 321
 322         entry = &chunk->mark;
 323         if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) {
 324                 fsnotify_put_mark(entry);
 325                 return -ENOSPC;
 326         }
 327
 328         spin_lock(&entry->lock);
 329         spin_lock(&hash_lock);
 330         if (tree->goner) {
 331                 spin_unlock(&hash_lock);
 332                 chunk->dead = 1;
 333                 spin_unlock(&entry->lock);
 334                 fsnotify_destroy_mark(entry, audit_tree_group);
 335                 fsnotify_put_mark(entry);
 336                 return 0;
 337         }
 338         chunk->owners[0].index = (1U << 31);
 339         chunk->owners[0].owner = tree;
 340         get_tree(tree);
 341         list_add(&chunk->owners[0].list, &tree->chunks);
 342         if (!tree->root) {
 343                 tree->root = chunk;
 344                 list_add(&tree->same_root, &chunk->trees);
 345         }
 346         insert_hash(chunk);
 347         spin_unlock(&hash_lock);
 348         spin_unlock(&entry->lock);
 349         fsnotify_put_mark(entry);       /* drop initial reference */
 350         return 0;
 351 }
 352
 353 /* the first tagged inode becomes root of tree */
 354 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
 355 {
 356         struct fsnotify_mark *old_entry, *chunk_entry;
 357         struct audit_tree *owner;
 358         struct audit_chunk *chunk, *old;
 359         struct node *p;
 360         int n;
 361
 362         old_entry = fsnotify_find_inode_mark(audit_tree_group, inode);
 363         if (!old_entry)
 364                 return create_chunk(inode, tree);
 365
 366         old = container_of(old_entry, struct audit_chunk, mark);
 367
 368         /* are we already there? */
 369         spin_lock(&hash_lock);
 370         for (n = 0; n < old->count; n++) {
 371                 if (old->owners[n].owner == tree) {
 372                         spin_unlock(&hash_lock);
 373                         fsnotify_put_mark(old_entry);
 374                         return 0;
 375                 }
 376         }
 377         spin_unlock(&hash_lock);
 378
 379         chunk = alloc_chunk(old->count + 1);
 380         if (!chunk) {
 381                 fsnotify_put_mark(old_entry);
 382                 return -ENOMEM;
 383         }
 384
 385         chunk_entry = &chunk->mark;
 386
 387         spin_lock(&old_entry->lock);
 388         if (!old_entry->i.inode) {
 389                 /* old_entry is being shot, lets just lie */
 390                 spin_unlock(&old_entry->lock);
 391                 fsnotify_put_mark(old_entry);
 392                 free_chunk(chunk);
 393                 return -ENOENT;
 394         }
 395
 396         fsnotify_duplicate_mark(chunk_entry, old_entry);
 397         if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->i.inode, NULL, 1)) {
 398                 spin_unlock(&old_entry->lock);
 399                 fsnotify_put_mark(chunk_entry);
 400                 fsnotify_put_mark(old_entry);
 401                 return -ENOSPC;
 402         }
 403
 404         /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
 405         spin_lock(&chunk_entry->lock);
 406         spin_lock(&hash_lock);
 407
 408         /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
 409         if (tree->goner) {
 410                 spin_unlock(&hash_lock);
 411                 chunk->dead = 1;
 412                 spin_unlock(&chunk_entry->lock);
 413                 spin_unlock(&old_entry->lock);
 414
 415                 fsnotify_destroy_mark(chunk_entry, audit_tree_group);
 416
 417                 fsnotify_put_mark(chunk_entry);
 418                 fsnotify_put_mark(old_entry);
 419                 return 0;
 420         }
 421         list_replace_init(&old->trees, &chunk->trees);
 422         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
 423                 struct audit_tree *s = old->owners[n].owner;
 424                 p->owner = s;
 425                 p->index = old->owners[n].index;
 426                 if (!s) /* result of fallback in untag */
 427                         continue;
 428                 get_tree(s);
 429                 list_replace_init(&old->owners[n].list, &p->list);
 430         }
 431         p->index = (chunk->count - 1) | (1U<<31);
 432         p->owner = tree;
 433         get_tree(tree);
 434         list_add(&p->list, &tree->chunks);
 435         list_replace_rcu(&old->hash, &chunk->hash);
 436         list_for_each_entry(owner, &chunk->trees, same_root)
 437                 owner->root = chunk;
 438         old->dead = 1;
 439         if (!tree->root) {
 440                 tree->root = chunk;
 441                 list_add(&tree->same_root, &chunk->trees);
 442         }
 443         spin_unlock(&hash_lock);
 444         spin_unlock(&chunk_entry->lock);
 445         spin_unlock(&old_entry->lock);
 446         fsnotify_destroy_mark(old_entry, audit_tree_group);
 447         fsnotify_put_mark(chunk_entry); /* drop initial reference */
 448         fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
 449         return 0;
 450 }
 451
 452 static void kill_rules(struct audit_tree *tree)
 453 {
 454         struct audit_krule *rule, *next;
 455         struct audit_entry *entry;
 456         struct audit_buffer *ab;
 457
 458         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
 459                 entry = container_of(rule, struct audit_entry, rule);
 460
 461                 list_del_init(&rule->rlist);
 462                 if (rule->tree) {
 463                         /* not a half-baked one */
 464                         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
 465                         audit_log_format(ab, "op=");
 466                         audit_log_string(ab, "remove rule");
 467                         audit_log_format(ab, " dir=");
 468                         audit_log_untrustedstring(ab, rule->tree->pathname);
 469                         audit_log_key(ab, rule->filterkey);
 470                         audit_log_format(ab, " list=%d res=1", rule->listnr);
 471                         audit_log_end(ab);
 472                         rule->tree = NULL;
 473                         list_del_rcu(&entry->list);
 474                         list_del(&entry->rule.list);
 475                         call_rcu(&entry->rcu, audit_free_rule_rcu);
 476                 }
 477         }
 478 }
 479
 480 /*
 481  * finish killing struct audit_tree
 482  */
 483 static void prune_one(struct audit_tree *victim)
 484 {
 485         spin_lock(&hash_lock);
 486         while (!list_empty(&victim->chunks)) {
 487                 struct node *p;
 488
 489                 p = list_entry(victim->chunks.next, struct node, list);
 490
 491                 untag_chunk(p);
 492         }
 493         spin_unlock(&hash_lock);
 494         put_tree(victim);
 495 }
 496
 497 /* trim the uncommitted chunks from tree */
 498
 499 static void trim_marked(struct audit_tree *tree)
 500 {
 501         struct list_head *p, *q;
 502         spin_lock(&hash_lock);
 503         if (tree->goner) {
 504                 spin_unlock(&hash_lock);
 505                 return;
 506         }
 507         /* reorder */
 508         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
 509                 struct node *node = list_entry(p, struct node, list);
 510                 q = p->next;
 511                 if (node->index & (1U<<31)) {
 512                         list_del_init(p);
 513                         list_add(p, &tree->chunks);
 514                 }
 515         }
 516
 517         while (!list_empty(&tree->chunks)) {
 518                 struct node *node;
 519
 520                 node = list_entry(tree->chunks.next, struct node, list);
 521
 522                 /* have we run out of marked? */
 523                 if (!(node->index & (1U<<31)))
 524                         break;
 525
 526                 untag_chunk(node);
 527         }
 528         if (!tree->root && !tree->goner) {
 529                 tree->goner = 1;
 530                 spin_unlock(&hash_lock);
 531                 mutex_lock(&audit_filter_mutex);
 532                 kill_rules(tree);
 533                 list_del_init(&tree->list);
 534                 mutex_unlock(&audit_filter_mutex);
 535                 prune_one(tree);
 536         } else {
 537                 spin_unlock(&hash_lock);
 538         }
 539 }
 540
 541 static void audit_schedule_prune(void);
 542
 543 /* called with audit_filter_mutex */
 544 int audit_remove_tree_rule(struct audit_krule *rule)
 545 {
 546         struct audit_tree *tree;
 547         tree = rule->tree;
 548         if (tree) {
 549                 spin_lock(&hash_lock);
 550                 list_del_init(&rule->rlist);
 551                 if (list_empty(&tree->rules) && !tree->goner) {
 552                         tree->root = NULL;
 553                         list_del_init(&tree->same_root);
 554                         tree->goner = 1;
 555                         list_move(&tree->list, &prune_list);
 556                         rule->tree = NULL;
 557                         spin_unlock(&hash_lock);
 558                         audit_schedule_prune();
 559                         return 1;
 560                 }
 561                 rule->tree = NULL;
 562                 spin_unlock(&hash_lock);
 563                 return 1;
 564         }
 565         return 0;
 566 }
 567
 568 static int compare_root(struct vfsmount *mnt, void *arg)
 569 {
 570         return mnt->mnt_root->d_inode == arg;
 571 }
 572
 573 void audit_trim_trees(void)
 574 {
 575         struct list_head cursor;
 576
 577         mutex_lock(&audit_filter_mutex);
 578         list_add(&cursor, &tree_list);
 579         while (cursor.next != &tree_list) {
 580                 struct audit_tree *tree;
 581                 struct path path;
 582                 struct vfsmount *root_mnt;
 583                 struct node *node;
 584                 int err;
 585
 586                 tree = container_of(cursor.next, struct audit_tree, list);
 587                 get_tree(tree);
 588                 list_del(&cursor);
 589                 list_add(&cursor, &tree->list);
 590                 mutex_unlock(&audit_filter_mutex);
 591
 592                 err = kern_path(tree->pathname, 0, &path);
 593                 if (err)
 594                         goto skip_it;
 595
 596                 root_mnt = collect_mounts(&path);
 597                 path_put(&path);
 598                 if (IS_ERR(root_mnt))
 599                         goto skip_it;
 600
 601                 spin_lock(&hash_lock);
 602                 list_for_each_entry(node, &tree->chunks, list) {
 603                         struct audit_chunk *chunk = find_chunk(node);
 604                         /* this could be NULL if the watch is dying else where... */
 605                         struct inode *inode = chunk->mark.i.inode;
 606                         node->index |= 1U<<31;
 607                         if (iterate_mounts(compare_root, inode, root_mnt))
 608                                 node->index &= ~(1U<<31);
 609                 }
 610                 spin_unlock(&hash_lock);
 611                 trim_marked(tree);
 612                 put_tree(tree);
 613                 drop_collected_mounts(root_mnt);
 614 skip_it:
 615                 mutex_lock(&audit_filter_mutex);
 616         }
 617         list_del(&cursor);
 618         mutex_unlock(&audit_filter_mutex);
 619 }
 620
 621 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
 622 {
 623
 624         if (pathname[0] != '/' ||
 625             rule->listnr != AUDIT_FILTER_EXIT ||
 626             op != Audit_equal ||
 627             rule->inode_f || rule->watch || rule->tree)
 628                 return -EINVAL;
 629         rule->tree = alloc_tree(pathname);
 630         if (!rule->tree)
 631                 return -ENOMEM;
 632         return 0;
 633 }
 634
 635 void audit_put_tree(struct audit_tree *tree)
 636 {
 637         put_tree(tree);
 638 }
 639
 640 static int tag_mount(struct vfsmount *mnt, void *arg)
 641 {
 642         return tag_chunk(mnt->mnt_root->d_inode, arg);
 643 }
 644
 645 /* called with audit_filter_mutex */
 646 int audit_add_tree_rule(struct audit_krule *rule)
 647 {
 648         struct audit_tree *seed = rule->tree, *tree;
 649         struct path path;
 650         struct vfsmount *mnt;
 651         int err;
 652
 653         list_for_each_entry(tree, &tree_list, list) {
 654                 if (!strcmp(seed->pathname, tree->pathname)) {
 655                         put_tree(seed);
 656                         rule->tree = tree;
 657                         list_add(&rule->rlist, &tree->rules);
 658                         return 0;
 659                 }
 660         }
 661         tree = seed;
 662         list_add(&tree->list, &tree_list);
 663         list_add(&rule->rlist, &tree->rules);
 664         /* do not set rule->tree yet */
 665         mutex_unlock(&audit_filter_mutex);
 666
 667         err = kern_path(tree->pathname, 0, &path);
 668         if (err)
 669                 goto Err;
 670         mnt = collect_mounts(&path);
 671         path_put(&path);
 672         if (IS_ERR(mnt)) {
 673                 err = PTR_ERR(mnt);
 674                 goto Err;
 675         }
 676
 677         get_tree(tree);
 678         err = iterate_mounts(tag_mount, tree, mnt);
 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 path path1, path2;
 714         struct vfsmount *tagged;
 715         int err;
 716
 717         err = kern_path(new, 0, &path2);
 718         if (err)
 719                 return err;
 720         tagged = collect_mounts(&path2);
 721         path_put(&path2);
 722         if (IS_ERR(tagged))
 723                 return PTR_ERR(tagged);
 724
 725         err = kern_path(old, 0, &path1);
 726         if (err) {
 727                 drop_collected_mounts(tagged);
 728                 return err;
 729         }
 730
 731         mutex_lock(&audit_filter_mutex);
 732         list_add(&barrier, &tree_list);
 733         list_add(&cursor, &barrier);
 734
 735         while (cursor.next != &tree_list) {
 736                 struct audit_tree *tree;
 737                 int good_one = 0;
 738
 739                 tree = container_of(cursor.next, struct audit_tree, list);
 740                 get_tree(tree);
 741                 list_del(&cursor);
 742                 list_add(&cursor, &tree->list);
 743                 mutex_unlock(&audit_filter_mutex);
 744
 745                 err = kern_path(tree->pathname, 0, &path2);
 746                 if (!err) {
 747                         good_one = path_is_under(&path1, &path2);
 748                         path_put(&path2);
 749                 }
 750
 751                 if (!good_one) {
 752                         put_tree(tree);
 753                         mutex_lock(&audit_filter_mutex);
 754                         continue;
 755                 }
 756
 757                 failed = iterate_mounts(tag_mount, tree, tagged);
 758                 if (failed) {
 759                         put_tree(tree);
 760                         mutex_lock(&audit_filter_mutex);
 761                         break;
 762                 }
 763
 764                 mutex_lock(&audit_filter_mutex);
 765                 spin_lock(&hash_lock);
 766                 if (!tree->goner) {
 767                         list_del(&tree->list);
 768                         list_add(&tree->list, &tree_list);
 769                 }
 770                 spin_unlock(&hash_lock);
 771                 put_tree(tree);
 772         }
 773
 774         while (barrier.prev != &tree_list) {
 775                 struct audit_tree *tree;
 776
 777                 tree = container_of(barrier.prev, struct audit_tree, list);
 778                 get_tree(tree);
 779                 list_del(&tree->list);
 780                 list_add(&tree->list, &barrier);
 781                 mutex_unlock(&audit_filter_mutex);
 782
 783                 if (!failed) {
 784                         struct node *node;
 785                         spin_lock(&hash_lock);
 786                         list_for_each_entry(node, &tree->chunks, list)
 787                                 node->index &= ~(1U<<31);
 788                         spin_unlock(&hash_lock);
 789                 } else {
 790                         trim_marked(tree);
 791                 }
 792
 793                 put_tree(tree);
 794                 mutex_lock(&audit_filter_mutex);
 795         }
 796         list_del(&barrier);
 797         list_del(&cursor);
 798         mutex_unlock(&audit_filter_mutex);
 799         path_put(&path1);
 800         drop_collected_mounts(tagged);
 801         return failed;
 802 }
 803
 804 /*
 805  * That gets run when evict_chunk() ends up needing to kill audit_tree.
 806  * Runs from a separate thread.
 807  */
 808 static int prune_tree_thread(void *unused)
 809 {
 810         mutex_lock(&audit_cmd_mutex);
 811         mutex_lock(&audit_filter_mutex);
 812
 813         while (!list_empty(&prune_list)) {
 814                 struct audit_tree *victim;
 815
 816                 victim = list_entry(prune_list.next, struct audit_tree, list);
 817                 list_del_init(&victim->list);
 818
 819                 mutex_unlock(&audit_filter_mutex);
 820
 821                 prune_one(victim);
 822
 823                 mutex_lock(&audit_filter_mutex);
 824         }
 825
 826         mutex_unlock(&audit_filter_mutex);
 827         mutex_unlock(&audit_cmd_mutex);
 828         return 0;
 829 }
 830
 831 static void audit_schedule_prune(void)
 832 {
 833         kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
 834 }
 835
 836 /*
 837  * ... and that one is done if evict_chunk() decides to delay until the end
 838  * of syscall.  Runs synchronously.
 839  */
 840 void audit_kill_trees(struct list_head *list)
 841 {
 842         mutex_lock(&audit_cmd_mutex);
 843         mutex_lock(&audit_filter_mutex);
 844
 845         while (!list_empty(list)) {
 846                 struct audit_tree *victim;
 847
 848                 victim = list_entry(list->next, struct audit_tree, list);
 849                 kill_rules(victim);
 850                 list_del_init(&victim->list);
 851
 852                 mutex_unlock(&audit_filter_mutex);
 853
 854                 prune_one(victim);
 855
 856                 mutex_lock(&audit_filter_mutex);
 857         }
 858
 859         mutex_unlock(&audit_filter_mutex);
 860         mutex_unlock(&audit_cmd_mutex);
 861 }
 862
 863 /*
 864  *  Here comes the stuff asynchronous to auditctl operations
 865  */
 866
 867 static void evict_chunk(struct audit_chunk *chunk)
 868 {
 869         struct audit_tree *owner;
 870         struct list_head *postponed = audit_killed_trees();
 871         int need_prune = 0;
 872         int n;
 873
 874         if (chunk->dead)
 875                 return;
 876
 877         chunk->dead = 1;
 878         mutex_lock(&audit_filter_mutex);
 879         spin_lock(&hash_lock);
 880         while (!list_empty(&chunk->trees)) {
 881                 owner = list_entry(chunk->trees.next,
 882                                    struct audit_tree, same_root);
 883                 owner->goner = 1;
 884                 owner->root = NULL;
 885                 list_del_init(&owner->same_root);
 886                 spin_unlock(&hash_lock);
 887                 if (!postponed) {
 888                         kill_rules(owner);
 889                         list_move(&owner->list, &prune_list);
 890                         need_prune = 1;
 891                 } else {
 892                         list_move(&owner->list, postponed);
 893                 }
 894                 spin_lock(&hash_lock);
 895         }
 896         list_del_rcu(&chunk->hash);
 897         for (n = 0; n < chunk->count; n++)
 898                 list_del_init(&chunk->owners[n].list);
 899         spin_unlock(&hash_lock);
 900         if (need_prune)
 901                 audit_schedule_prune();
 902         mutex_unlock(&audit_filter_mutex);
 903 }
 904
 905 static int audit_tree_handle_event(struct fsnotify_group *group,
 906                                    struct fsnotify_mark *inode_mark,
 907                                    struct fsnotify_mark *vfsmonut_mark,
 908                                    struct fsnotify_event *event)
 909 {
 910         BUG();
 911         return -EOPNOTSUPP;
 912 }
 913
 914 static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
 915 {
 916         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
 917
 918         evict_chunk(chunk);
 919
 920         /*
 921          * We are guaranteed to have at least one reference to the mark from
 922          * either the inode or the caller of fsnotify_destroy_mark().
 923          */
 924         BUG_ON(atomic_read(&entry->refcnt) < 1);
 925 }
 926
 927 static bool audit_tree_send_event(struct fsnotify_group *group, struct inode *inode,
 928                                   struct fsnotify_mark *inode_mark,
 929                                   struct fsnotify_mark *vfsmount_mark,
 930                                   __u32 mask, void *data, int data_type)
 931 {
 932         return false;
 933 }
 934
 935 static const struct fsnotify_ops audit_tree_ops = {
 936         .handle_event = audit_tree_handle_event,
 937         .should_send_event = audit_tree_send_event,
 938         .free_group_priv = NULL,
 939         .free_event_priv = NULL,
 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);