kernel/audit_tree.c

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