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