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                 fsnotify_put_mark(entry);
 260                 goto out;
 261         }
 262
 263         if (!new)
 264                 goto Fallback;
 265
 266         fsnotify_duplicate_mark(&new->mark, entry);
 267         if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.i.inode, NULL, 1)) {
 268                 free_chunk(new);
 269                 goto Fallback;
 270         }
 271
 272         chunk->dead = 1;
 273         spin_lock(&hash_lock);
 274         list_replace_init(&chunk->trees, &new->trees);
 275         if (owner->root == chunk) {
 276                 list_del_init(&owner->same_root);
 277                 owner->root = NULL;
 278         }
 279
 280         for (i = j = 0; j <= size; i++, j++) {
 281                 struct audit_tree *s;
 282                 if (&chunk->owners[j] == p) {
 283                         list_del_init(&p->list);
 284                         i--;
 285                         continue;
 286                 }
 287                 s = chunk->owners[j].owner;
 288                 new->owners[i].owner = s;
 289                 new->owners[i].index = chunk->owners[j].index - j + i;
 290                 if (!s) /* result of earlier fallback */
 291                         continue;
 292                 get_tree(s);
 293                 list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
 294         }
 295
 296         list_replace_rcu(&chunk->hash, &new->hash);
 297         list_for_each_entry(owner, &new->trees, same_root)
 298                 owner->root = new;
 299         spin_unlock(&hash_lock);
 300         spin_unlock(&entry->lock);
 301         fsnotify_destroy_mark(entry);
 302         fsnotify_put_mark(entry);
 303         goto out;
 304
 305 Fallback:
 306         // do the best we can
 307         spin_lock(&hash_lock);
 308         if (owner->root == chunk) {
 309                 list_del_init(&owner->same_root);
 310                 owner->root = NULL;
 311         }
 312         list_del_init(&p->list);
 313         p->owner = NULL;
 314         put_tree(owner);
 315         spin_unlock(&hash_lock);
 316         spin_unlock(&entry->lock);
 317 out:
 318         fsnotify_put_mark(entry);
 319         spin_lock(&hash_lock);
 320 }
 321
 322 static int create_chunk(struct inode *inode, struct audit_tree *tree)
 323 {
 324         struct fsnotify_mark *entry;
 325         struct audit_chunk *chunk = alloc_chunk(1);
 326         if (!chunk)
 327                 return -ENOMEM;
 328
 329         entry = &chunk->mark;
 330         if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) {
 331                 free_chunk(chunk);
 332                 return -ENOSPC;
 333         }
 334
 335         spin_lock(&entry->lock);
 336         spin_lock(&hash_lock);
 337         if (tree->goner) {
 338                 spin_unlock(&hash_lock);
 339                 chunk->dead = 1;
 340                 spin_unlock(&entry->lock);
 341                 fsnotify_destroy_mark(entry);
 342                 fsnotify_put_mark(entry);
 343                 return 0;
 344         }
 345         chunk->owners[0].index = (1U << 31);
 346         chunk->owners[0].owner = tree;
 347         get_tree(tree);
 348         list_add(&chunk->owners[0].list, &tree->chunks);
 349         if (!tree->root) {
 350                 tree->root = chunk;
 351                 list_add(&tree->same_root, &chunk->trees);
 352         }
 353         insert_hash(chunk);
 354         spin_unlock(&hash_lock);
 355         spin_unlock(&entry->lock);
 356         return 0;
 357 }
 358
 359 /* the first tagged inode becomes root of tree */
 360 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
 361 {
 362         struct fsnotify_mark *old_entry, *chunk_entry;
 363         struct audit_tree *owner;
 364         struct audit_chunk *chunk, *old;
 365         struct node *p;
 366         int n;
 367
 368         old_entry = fsnotify_find_inode_mark(audit_tree_group, inode);
 369         if (!old_entry)
 370                 return create_chunk(inode, tree);
 371
 372         old = container_of(old_entry, struct audit_chunk, mark);
 373
 374         /* are we already there? */
 375         spin_lock(&hash_lock);
 376         for (n = 0; n < old->count; n++) {
 377                 if (old->owners[n].owner == tree) {
 378                         spin_unlock(&hash_lock);
 379                         fsnotify_put_mark(old_entry);
 380                         return 0;
 381                 }
 382         }
 383         spin_unlock(&hash_lock);
 384
 385         chunk = alloc_chunk(old->count + 1);
 386         if (!chunk) {
 387                 fsnotify_put_mark(old_entry);
 388                 return -ENOMEM;
 389         }
 390
 391         chunk_entry = &chunk->mark;
 392
 393         spin_lock(&old_entry->lock);
 394         if (!old_entry->i.inode) {
 395                 /* old_entry is being shot, lets just lie */
 396                 spin_unlock(&old_entry->lock);
 397                 fsnotify_put_mark(old_entry);
 398                 free_chunk(chunk);
 399                 return -ENOENT;
 400         }
 401
 402         fsnotify_duplicate_mark(chunk_entry, old_entry);
 403         if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->i.inode, NULL, 1)) {
 404                 spin_unlock(&old_entry->lock);
 405                 free_chunk(chunk);
 406                 fsnotify_put_mark(old_entry);
 407                 return -ENOSPC;
 408         }
 409
 410         /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
 411         spin_lock(&chunk_entry->lock);
 412         spin_lock(&hash_lock);
 413
 414         /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
 415         if (tree->goner) {
 416                 spin_unlock(&hash_lock);
 417                 chunk->dead = 1;
 418                 spin_unlock(&chunk_entry->lock);
 419                 spin_unlock(&old_entry->lock);
 420
 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         fsnotify_put_mark(old_entry); /* and kill it */
 455         return 0;
 456 }
 457
 458 static void kill_rules(struct audit_tree *tree)
 459 {
 460         struct audit_krule *rule, *next;
 461         struct audit_entry *entry;
 462         struct audit_buffer *ab;
 463
 464         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
 465                 entry = container_of(rule, struct audit_entry, rule);
 466
 467                 list_del_init(&rule->rlist);
 468                 if (rule->tree) {
 469                         /* not a half-baked one */
 470                         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
 471                         audit_log_format(ab, "op=");
 472                         audit_log_string(ab, "remove rule");
 473                         audit_log_format(ab, " dir=");
 474                         audit_log_untrustedstring(ab, rule->tree->pathname);
 475                         audit_log_key(ab, rule->filterkey);
 476                         audit_log_format(ab, " list=%d res=1", rule->listnr);
 477                         audit_log_end(ab);
 478                         rule->tree = NULL;
 479                         list_del_rcu(&entry->list);
 480                         list_del(&entry->rule.list);
 481                         call_rcu(&entry->rcu, audit_free_rule_rcu);
 482                 }
 483         }
 484 }
 485
 486 /*
 487  * finish killing struct audit_tree
 488  */
 489 static void prune_one(struct audit_tree *victim)
 490 {
 491         spin_lock(&hash_lock);
 492         while (!list_empty(&victim->chunks)) {
 493                 struct node *p;
 494
 495                 p = list_entry(victim->chunks.next, struct node, list);
 496
 497                 untag_chunk(p);
 498         }
 499         spin_unlock(&hash_lock);
 500         put_tree(victim);
 501 }
 502
 503 /* trim the uncommitted chunks from tree */
 504
 505 static void trim_marked(struct audit_tree *tree)
 506 {
 507         struct list_head *p, *q;
 508         spin_lock(&hash_lock);
 509         if (tree->goner) {
 510                 spin_unlock(&hash_lock);
 511                 return;
 512         }
 513         /* reorder */
 514         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
 515                 struct node *node = list_entry(p, struct node, list);
 516                 q = p->next;
 517                 if (node->index & (1U<<31)) {
 518                         list_del_init(p);
 519                         list_add(p, &tree->chunks);
 520                 }
 521         }
 522
 523         while (!list_empty(&tree->chunks)) {
 524                 struct node *node;
 525
 526                 node = list_entry(tree->chunks.next, struct node, list);
 527
 528                 /* have we run out of marked? */
 529                 if (!(node->index & (1U<<31)))
 530                         break;
 531
 532                 untag_chunk(node);
 533         }
 534         if (!tree->root && !tree->goner) {
 535                 tree->goner = 1;
 536                 spin_unlock(&hash_lock);
 537                 mutex_lock(&audit_filter_mutex);
 538                 kill_rules(tree);
 539                 list_del_init(&tree->list);
 540                 mutex_unlock(&audit_filter_mutex);
 541                 prune_one(tree);
 542         } else {
 543                 spin_unlock(&hash_lock);
 544         }
 545 }
 546
 547 static void audit_schedule_prune(void);
 548
 549 /* called with audit_filter_mutex */
 550 int audit_remove_tree_rule(struct audit_krule *rule)
 551 {
 552         struct audit_tree *tree;
 553         tree = rule->tree;
 554         if (tree) {
 555                 spin_lock(&hash_lock);
 556                 list_del_init(&rule->rlist);
 557                 if (list_empty(&tree->rules) && !tree->goner) {
 558                         tree->root = NULL;
 559                         list_del_init(&tree->same_root);
 560                         tree->goner = 1;
 561                         list_move(&tree->list, &prune_list);
 562                         rule->tree = NULL;
 563                         spin_unlock(&hash_lock);
 564                         audit_schedule_prune();
 565                         return 1;
 566                 }
 567                 rule->tree = NULL;
 568                 spin_unlock(&hash_lock);
 569                 return 1;
 570         }
 571         return 0;
 572 }
 573
 574 static int compare_root(struct vfsmount *mnt, void *arg)
 575 {
 576         return mnt->mnt_root->d_inode == arg;
 577 }
 578
 579 void audit_trim_trees(void)
 580 {
 581         struct list_head cursor;
 582
 583         mutex_lock(&audit_filter_mutex);
 584         list_add(&cursor, &tree_list);
 585         while (cursor.next != &tree_list) {
 586                 struct audit_tree *tree;
 587                 struct path path;
 588                 struct vfsmount *root_mnt;
 589                 struct node *node;
 590                 int err;
 591
 592                 tree = container_of(cursor.next, struct audit_tree, list);
 593                 get_tree(tree);
 594                 list_del(&cursor);
 595                 list_add(&cursor, &tree->list);
 596                 mutex_unlock(&audit_filter_mutex);
 597
 598                 err = kern_path(tree->pathname, 0, &path);
 599                 if (err)
 600                         goto skip_it;
 601
 602                 root_mnt = collect_mounts(&path);
 603                 path_put(&path);
 604                 if (!root_mnt)
 605                         goto skip_it;
 606
 607                 spin_lock(&hash_lock);
 608                 list_for_each_entry(node, &tree->chunks, list) {
 609                         struct audit_chunk *chunk = find_chunk(node);
 610                         /* this could be NULL if the watch is dieing else where... */
 611                         struct inode *inode = chunk->mark.i.inode;
 612                         node->index |= 1U<<31;
 613                         if (iterate_mounts(compare_root, inode, root_mnt))
 614                                 node->index &= ~(1U<<31);
 615                 }
 616                 spin_unlock(&hash_lock);
 617                 trim_marked(tree);
 618                 put_tree(tree);
 619                 drop_collected_mounts(root_mnt);
 620 skip_it:
 621                 mutex_lock(&audit_filter_mutex);
 622         }
 623         list_del(&cursor);
 624         mutex_unlock(&audit_filter_mutex);
 625 }
 626
 627 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
 628 {
 629
 630         if (pathname[0] != '/' ||
 631             rule->listnr != AUDIT_FILTER_EXIT ||
 632             op != Audit_equal ||
 633             rule->inode_f || rule->watch || rule->tree)
 634                 return -EINVAL;
 635         rule->tree = alloc_tree(pathname);
 636         if (!rule->tree)
 637                 return -ENOMEM;
 638         return 0;
 639 }
 640
 641 void audit_put_tree(struct audit_tree *tree)
 642 {
 643         put_tree(tree);
 644 }
 645
 646 static int tag_mount(struct vfsmount *mnt, void *arg)
 647 {
 648         return tag_chunk(mnt->mnt_root->d_inode, arg);
 649 }
 650
 651 /* called with audit_filter_mutex */
 652 int audit_add_tree_rule(struct audit_krule *rule)
 653 {
 654         struct audit_tree *seed = rule->tree, *tree;
 655         struct path path;
 656         struct vfsmount *mnt;
 657         int err;
 658
 659         list_for_each_entry(tree, &tree_list, list) {
 660                 if (!strcmp(seed->pathname, tree->pathname)) {
 661                         put_tree(seed);
 662                         rule->tree = tree;
 663                         list_add(&rule->rlist, &tree->rules);
 664                         return 0;
 665                 }
 666         }
 667         tree = seed;
 668         list_add(&tree->list, &tree_list);
 669         list_add(&rule->rlist, &tree->rules);
 670         /* do not set rule->tree yet */
 671         mutex_unlock(&audit_filter_mutex);
 672
 673         err = kern_path(tree->pathname, 0, &path);
 674         if (err)
 675                 goto Err;
 676         mnt = collect_mounts(&path);
 677         path_put(&path);
 678         if (!mnt) {
 679                 err = -ENOMEM;
 680                 goto Err;
 681         }
 682
 683         get_tree(tree);
 684         err = iterate_mounts(tag_mount, tree, mnt);
 685         drop_collected_mounts(mnt);
 686
 687         if (!err) {
 688                 struct node *node;
 689                 spin_lock(&hash_lock);
 690                 list_for_each_entry(node, &tree->chunks, list)
 691                         node->index &= ~(1U<<31);
 692                 spin_unlock(&hash_lock);
 693         } else {
 694                 trim_marked(tree);
 695                 goto Err;
 696         }
 697
 698         mutex_lock(&audit_filter_mutex);
 699         if (list_empty(&rule->rlist)) {
 700                 put_tree(tree);
 701                 return -ENOENT;
 702         }
 703         rule->tree = tree;
 704         put_tree(tree);
 705
 706         return 0;
 707 Err:
 708         mutex_lock(&audit_filter_mutex);
 709         list_del_init(&tree->list);
 710         list_del_init(&tree->rules);
 711         put_tree(tree);
 712         return err;
 713 }
 714
 715 int audit_tag_tree(char *old, char *new)
 716 {
 717         struct list_head cursor, barrier;
 718         int failed = 0;
 719         struct path path1, path2;
 720         struct vfsmount *tagged;
 721         int err;
 722
 723         err = kern_path(new, 0, &path2);
 724         if (err)
 725                 return err;
 726         tagged = collect_mounts(&path2);
 727         path_put(&path2);
 728         if (!tagged)
 729                 return -ENOMEM;
 730
 731         err = kern_path(old, 0, &path1);
 732         if (err) {
 733                 drop_collected_mounts(tagged);
 734                 return err;
 735         }
 736
 737         mutex_lock(&audit_filter_mutex);
 738         list_add(&barrier, &tree_list);
 739         list_add(&cursor, &barrier);
 740
 741         while (cursor.next != &tree_list) {
 742                 struct audit_tree *tree;
 743                 int good_one = 0;
 744
 745                 tree = container_of(cursor.next, struct audit_tree, list);
 746                 get_tree(tree);
 747                 list_del(&cursor);
 748                 list_add(&cursor, &tree->list);
 749                 mutex_unlock(&audit_filter_mutex);
 750
 751                 err = kern_path(tree->pathname, 0, &path2);
 752                 if (!err) {
 753                         good_one = path_is_under(&path1, &path2);
 754                         path_put(&path2);
 755                 }
 756
 757                 if (!good_one) {
 758                         put_tree(tree);
 759                         mutex_lock(&audit_filter_mutex);
 760                         continue;
 761                 }
 762
 763                 failed = iterate_mounts(tag_mount, tree, tagged);
 764                 if (failed) {
 765                         put_tree(tree);
 766                         mutex_lock(&audit_filter_mutex);
 767                         break;
 768                 }
 769
 770                 mutex_lock(&audit_filter_mutex);
 771                 spin_lock(&hash_lock);
 772                 if (!tree->goner) {
 773                         list_del(&tree->list);
 774                         list_add(&tree->list, &tree_list);
 775                 }
 776                 spin_unlock(&hash_lock);
 777                 put_tree(tree);
 778         }
 779
 780         while (barrier.prev != &tree_list) {
 781                 struct audit_tree *tree;
 782
 783                 tree = container_of(barrier.prev, struct audit_tree, list);
 784                 get_tree(tree);
 785                 list_del(&tree->list);
 786                 list_add(&tree->list, &barrier);
 787                 mutex_unlock(&audit_filter_mutex);
 788
 789                 if (!failed) {
 790                         struct node *node;
 791                         spin_lock(&hash_lock);
 792                         list_for_each_entry(node, &tree->chunks, list)
 793                                 node->index &= ~(1U<<31);
 794                         spin_unlock(&hash_lock);
 795                 } else {
 796                         trim_marked(tree);
 797                 }
 798
 799                 put_tree(tree);
 800                 mutex_lock(&audit_filter_mutex);
 801         }
 802         list_del(&barrier);
 803         list_del(&cursor);
 804         mutex_unlock(&audit_filter_mutex);
 805         path_put(&path1);
 806         drop_collected_mounts(tagged);
 807         return failed;
 808 }
 809
 810 /*
 811  * That gets run when evict_chunk() ends up needing to kill audit_tree.
 812  * Runs from a separate thread.
 813  */
 814 static int prune_tree_thread(void *unused)
 815 {
 816         mutex_lock(&audit_cmd_mutex);
 817         mutex_lock(&audit_filter_mutex);
 818
 819         while (!list_empty(&prune_list)) {
 820                 struct audit_tree *victim;
 821
 822                 victim = list_entry(prune_list.next, struct audit_tree, list);
 823                 list_del_init(&victim->list);
 824
 825                 mutex_unlock(&audit_filter_mutex);
 826
 827                 prune_one(victim);
 828
 829                 mutex_lock(&audit_filter_mutex);
 830         }
 831
 832         mutex_unlock(&audit_filter_mutex);
 833         mutex_unlock(&audit_cmd_mutex);
 834         return 0;
 835 }
 836
 837 static void audit_schedule_prune(void)
 838 {
 839         kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
 840 }
 841
 842 /*
 843  * ... and that one is done if evict_chunk() decides to delay until the end
 844  * of syscall.  Runs synchronously.
 845  */
 846 void audit_kill_trees(struct list_head *list)
 847 {
 848         mutex_lock(&audit_cmd_mutex);
 849         mutex_lock(&audit_filter_mutex);
 850
 851         while (!list_empty(list)) {
 852                 struct audit_tree *victim;
 853
 854                 victim = list_entry(list->next, struct audit_tree, list);
 855                 kill_rules(victim);
 856                 list_del_init(&victim->list);
 857
 858                 mutex_unlock(&audit_filter_mutex);
 859
 860                 prune_one(victim);
 861
 862                 mutex_lock(&audit_filter_mutex);
 863         }
 864
 865         mutex_unlock(&audit_filter_mutex);
 866         mutex_unlock(&audit_cmd_mutex);
 867 }
 868
 869 /*
 870  *  Here comes the stuff asynchronous to auditctl operations
 871  */
 872
 873 static void evict_chunk(struct audit_chunk *chunk)
 874 {
 875         struct audit_tree *owner;
 876         struct list_head *postponed = audit_killed_trees();
 877         int need_prune = 0;
 878         int n;
 879
 880         if (chunk->dead)
 881                 return;
 882
 883         chunk->dead = 1;
 884         mutex_lock(&audit_filter_mutex);
 885         spin_lock(&hash_lock);
 886         while (!list_empty(&chunk->trees)) {
 887                 owner = list_entry(chunk->trees.next,
 888                                    struct audit_tree, same_root);
 889                 owner->goner = 1;
 890                 owner->root = NULL;
 891                 list_del_init(&owner->same_root);
 892                 spin_unlock(&hash_lock);
 893                 if (!postponed) {
 894                         kill_rules(owner);
 895                         list_move(&owner->list, &prune_list);
 896                         need_prune = 1;
 897                 } else {
 898                         list_move(&owner->list, postponed);
 899                 }
 900                 spin_lock(&hash_lock);
 901         }
 902         list_del_rcu(&chunk->hash);
 903         for (n = 0; n < chunk->count; n++)
 904                 list_del_init(&chunk->owners[n].list);
 905         spin_unlock(&hash_lock);
 906         if (need_prune)
 907                 audit_schedule_prune();
 908         mutex_unlock(&audit_filter_mutex);
 909 }
 910
 911 static int audit_tree_handle_event(struct fsnotify_group *group,
 912                                    struct fsnotify_mark *inode_mark,
 913                                    struct fsnotify_mark *vfsmonut_mark,
 914                                    struct fsnotify_event *event)
 915 {
 916         BUG();
 917         return -EOPNOTSUPP;
 918 }
 919
 920 static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
 921 {
 922         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
 923
 924         evict_chunk(chunk);
 925         fsnotify_put_mark(entry);
 926 }
 927
 928 static bool audit_tree_send_event(struct fsnotify_group *group, struct inode *inode,
 929                                   struct fsnotify_mark *inode_mark,
 930                                   struct fsnotify_mark *vfsmount_mark,
 931                                   __u32 mask, void *data, int data_type)
 932 {
 933         return false;
 934 }
 935
 936 static const struct fsnotify_ops audit_tree_ops = {
 937         .handle_event = audit_tree_handle_event,
 938         .should_send_event = audit_tree_send_event,
 939         .free_group_priv = NULL,
 940         .free_event_priv = NULL,
 941         .freeing_mark = audit_tree_freeing_mark,
 942 };
 943
 944 static int __init audit_tree_init(void)
 945 {
 946         int i;
 947
 948         audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
 949         if (IS_ERR(audit_tree_group))
 950                 audit_panic("cannot initialize fsnotify group for rectree watches");
 951
 952         for (i = 0; i < HASH_SIZE; i++)
 953                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
 954
 955         return 0;
 956 }
 957 __initcall(audit_tree_init);