1// SPDX-License-Identifier: GPL-2.0
   2#include "audit.h"
   3#include <linux/fsnotify_backend.h>
   4#include <linux/namei.h>
   5#include <linux/mount.h>
   6#include <linux/kthread.h>
   7#include <linux/refcount.h>
   8#include <linux/slab.h>
   9
  10struct audit_tree;
  11struct audit_chunk;
  12
  13struct audit_tree {
  14	refcount_t count;
  15	int goner;
  16	struct audit_chunk *root;
  17	struct list_head chunks;
  18	struct list_head rules;
  19	struct list_head list;
  20	struct list_head same_root;
  21	struct rcu_head head;
  22	char pathname[];
  23};
  24
  25struct audit_chunk {
  26	struct list_head hash;
  27	unsigned long key;
  28	struct fsnotify_mark *mark;
  29	struct list_head trees;		/* with root here */
 
  30	int count;
  31	atomic_long_t refs;
  32	struct rcu_head head;
  33	struct audit_node {
  34		struct list_head list;
  35		struct audit_tree *owner;
  36		unsigned index;		/* index; upper bit indicates 'will prune' */
  37	} owners[] __counted_by(count);
  38};
  39
  40struct audit_tree_mark {
  41	struct fsnotify_mark mark;
  42	struct audit_chunk *chunk;
  43};
  44
  45static LIST_HEAD(tree_list);
  46static LIST_HEAD(prune_list);
  47static struct task_struct *prune_thread;
  48
  49/*
  50 * One struct chunk is attached to each inode of interest through
  51 * audit_tree_mark (fsnotify mark). We replace struct chunk on tagging /
  52 * untagging, the mark is stable as long as there is chunk attached. The
  53 * association between mark and chunk is protected by hash_lock and
  54 * audit_tree_group->mark_mutex. Thus as long as we hold
  55 * audit_tree_group->mark_mutex and check that the mark is alive by
  56 * FSNOTIFY_MARK_FLAG_ATTACHED flag check, we are sure the mark points to
  57 * the current chunk.
  58 *
  59 * Rules have pointer to struct audit_tree.
  60 * Rules have struct list_head rlist forming a list of rules over
  61 * the same tree.
  62 * References to struct chunk are collected at audit_inode{,_child}()
  63 * time and used in AUDIT_TREE rule matching.
  64 * These references are dropped at the same time we are calling
  65 * audit_free_names(), etc.
  66 *
  67 * Cyclic lists galore:
  68 * tree.chunks anchors chunk.owners[].list			hash_lock
  69 * tree.rules anchors rule.rlist				audit_filter_mutex
  70 * chunk.trees anchors tree.same_root				hash_lock
  71 * chunk.hash is a hash with middle bits of watch.inode as
  72 * a hash function.						RCU, hash_lock
  73 *
  74 * tree is refcounted; one reference for "some rules on rules_list refer to
  75 * it", one for each chunk with pointer to it.
  76 *
  77 * chunk is refcounted by embedded .refs. Mark associated with the chunk holds
  78 * one chunk reference. This reference is dropped either when a mark is going
  79 * to be freed (corresponding inode goes away) or when chunk attached to the
  80 * mark gets replaced. This reference must be dropped using
  81 * audit_mark_put_chunk() to make sure the reference is dropped only after RCU
  82 * grace period as it protects RCU readers of the hash table.
  83 *
  84 * node.index allows to get from node.list to containing chunk.
  85 * MSB of that sucker is stolen to mark taggings that we might have to
  86 * revert - several operations have very unpleasant cleanup logics and
  87 * that makes a difference.  Some.
  88 */
  89
  90static struct fsnotify_group *audit_tree_group __ro_after_init;
  91static struct kmem_cache *audit_tree_mark_cachep __ro_after_init;
  92
  93static struct audit_tree *alloc_tree(const char *s)
  94{
  95	struct audit_tree *tree;
  96
  97	tree = kmalloc(struct_size(tree, pathname, strlen(s) + 1), GFP_KERNEL);
  98	if (tree) {
  99		refcount_set(&tree->count, 1);
 100		tree->goner = 0;
 101		INIT_LIST_HEAD(&tree->chunks);
 102		INIT_LIST_HEAD(&tree->rules);
 103		INIT_LIST_HEAD(&tree->list);
 104		INIT_LIST_HEAD(&tree->same_root);
 105		tree->root = NULL;
 106		strcpy(tree->pathname, s);
 107	}
 108	return tree;
 109}
 110
 111static inline void get_tree(struct audit_tree *tree)
 112{
 113	refcount_inc(&tree->count);
 114}
 115
 116static inline void put_tree(struct audit_tree *tree)
 117{
 118	if (refcount_dec_and_test(&tree->count))
 119		kfree_rcu(tree, head);
 120}
 121
 122/* to avoid bringing the entire thing in audit.h */
 123const char *audit_tree_path(struct audit_tree *tree)
 124{
 125	return tree->pathname;
 126}
 127
 128static void free_chunk(struct audit_chunk *chunk)
 129{
 130	int i;
 131
 132	for (i = 0; i < chunk->count; i++) {
 133		if (chunk->owners[i].owner)
 134			put_tree(chunk->owners[i].owner);
 135	}
 136	kfree(chunk);
 137}
 138
 139void audit_put_chunk(struct audit_chunk *chunk)
 140{
 141	if (atomic_long_dec_and_test(&chunk->refs))
 142		free_chunk(chunk);
 143}
 144
 145static void __put_chunk(struct rcu_head *rcu)
 146{
 147	struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
 148	audit_put_chunk(chunk);
 149}
 150
 151/*
 152 * Drop reference to the chunk that was held by the mark. This is the reference
 153 * that gets dropped after we've removed the chunk from the hash table and we
 154 * use it to make sure chunk cannot be freed before RCU grace period expires.
 155 */
 156static void audit_mark_put_chunk(struct audit_chunk *chunk)
 157{
 
 158	call_rcu(&chunk->head, __put_chunk);
 159}
 160
 161static inline struct audit_tree_mark *audit_mark(struct fsnotify_mark *mark)
 162{
 163	return container_of(mark, struct audit_tree_mark, mark);
 164}
 165
 166static struct audit_chunk *mark_chunk(struct fsnotify_mark *mark)
 167{
 168	return audit_mark(mark)->chunk;
 169}
 170
 171static void audit_tree_destroy_watch(struct fsnotify_mark *mark)
 172{
 173	kmem_cache_free(audit_tree_mark_cachep, audit_mark(mark));
 174}
 175
 176static struct fsnotify_mark *alloc_mark(void)
 177{
 178	struct audit_tree_mark *amark;
 179
 180	amark = kmem_cache_zalloc(audit_tree_mark_cachep, GFP_KERNEL);
 181	if (!amark)
 182		return NULL;
 183	fsnotify_init_mark(&amark->mark, audit_tree_group);
 184	amark->mark.mask = FS_IN_IGNORED;
 185	return &amark->mark;
 186}
 187
 188static struct audit_chunk *alloc_chunk(int count)
 189{
 190	struct audit_chunk *chunk;
 
 191	int i;
 192
 193	chunk = kzalloc(struct_size(chunk, owners, count), GFP_KERNEL);
 
 194	if (!chunk)
 195		return NULL;
 196
 197	INIT_LIST_HEAD(&chunk->hash);
 198	INIT_LIST_HEAD(&chunk->trees);
 199	chunk->count = count;
 200	atomic_long_set(&chunk->refs, 1);
 201	for (i = 0; i < count; i++) {
 202		INIT_LIST_HEAD(&chunk->owners[i].list);
 203		chunk->owners[i].index = i;
 204	}
 
 205	return chunk;
 206}
 207
 208enum {HASH_SIZE = 128};
 209static struct list_head chunk_hash_heads[HASH_SIZE];
 210static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
 211
 212/* Function to return search key in our hash from inode. */
 213static unsigned long inode_to_key(const struct inode *inode)
 214{
 215	/* Use address pointed to by connector->obj as the key */
 216	return (unsigned long)&inode->i_fsnotify_marks;
 217}
 218
 219static inline struct list_head *chunk_hash(unsigned long key)
 220{
 221	unsigned long n = key / L1_CACHE_BYTES;
 222	return chunk_hash_heads + n % HASH_SIZE;
 223}
 224
 225/* hash_lock & mark->group->mark_mutex is held by caller */
 226static void insert_hash(struct audit_chunk *chunk)
 227{
 
 228	struct list_head *list;
 229
 230	/*
 231	 * Make sure chunk is fully initialized before making it visible in the
 232	 * hash. Pairs with a data dependency barrier in READ_ONCE() in
 233	 * audit_tree_lookup().
 234	 */
 235	smp_wmb();
 236	WARN_ON_ONCE(!chunk->key);
 237	list = chunk_hash(chunk->key);
 238	list_add_rcu(&chunk->hash, list);
 239}
 240
 241/* called under rcu_read_lock */
 242struct audit_chunk *audit_tree_lookup(const struct inode *inode)
 243{
 244	unsigned long key = inode_to_key(inode);
 245	struct list_head *list = chunk_hash(key);
 246	struct audit_chunk *p;
 247
 248	list_for_each_entry_rcu(p, list, hash) {
 249		/*
 250		 * We use a data dependency barrier in READ_ONCE() to make sure
 251		 * the chunk we see is fully initialized.
 252		 */
 253		if (READ_ONCE(p->key) == key) {
 254			atomic_long_inc(&p->refs);
 255			return p;
 256		}
 257	}
 258	return NULL;
 259}
 260
 261bool audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
 262{
 263	int n;
 264	for (n = 0; n < chunk->count; n++)
 265		if (chunk->owners[n].owner == tree)
 266			return true;
 267	return false;
 268}
 269
 270/* tagging and untagging inodes with trees */
 271
 272static struct audit_chunk *find_chunk(struct audit_node *p)
 273{
 274	int index = p->index & ~(1U<<31);
 275	p -= index;
 276	return container_of(p, struct audit_chunk, owners[0]);
 277}
 278
 279static void replace_mark_chunk(struct fsnotify_mark *mark,
 280			       struct audit_chunk *chunk)
 281{
 282	struct audit_chunk *old;
 283
 284	assert_spin_locked(&hash_lock);
 285	old = mark_chunk(mark);
 286	audit_mark(mark)->chunk = chunk;
 287	if (chunk)
 288		chunk->mark = mark;
 289	if (old)
 290		old->mark = NULL;
 291}
 292
 293static void replace_chunk(struct audit_chunk *new, struct audit_chunk *old)
 294{
 
 
 
 295	struct audit_tree *owner;
 
 296	int i, j;
 297
 298	new->key = old->key;
 299	list_splice_init(&old->trees, &new->trees);
 300	list_for_each_entry(owner, &new->trees, same_root)
 301		owner->root = new;
 302	for (i = j = 0; j < old->count; i++, j++) {
 303		if (!old->owners[j].owner) {
 304			i--;
 305			continue;
 306		}
 307		owner = old->owners[j].owner;
 308		new->owners[i].owner = owner;
 309		new->owners[i].index = old->owners[j].index - j + i;
 310		if (!owner) /* result of earlier fallback */
 311			continue;
 312		get_tree(owner);
 313		list_replace_init(&old->owners[j].list, &new->owners[i].list);
 314	}
 315	replace_mark_chunk(old->mark, new);
 316	/*
 317	 * Make sure chunk is fully initialized before making it visible in the
 318	 * hash. Pairs with a data dependency barrier in READ_ONCE() in
 319	 * audit_tree_lookup().
 320	 */
 321	smp_wmb();
 322	list_replace_rcu(&old->hash, &new->hash);
 323}
 324
 325static void remove_chunk_node(struct audit_chunk *chunk, struct audit_node *p)
 326{
 327	struct audit_tree *owner = p->owner;
 328
 329	if (owner->root == chunk) {
 330		list_del_init(&owner->same_root);
 331		owner->root = NULL;
 332	}
 333	list_del_init(&p->list);
 334	p->owner = NULL;
 335	put_tree(owner);
 336}
 337
 338static int chunk_count_trees(struct audit_chunk *chunk)
 339{
 340	int i;
 341	int ret = 0;
 342
 343	for (i = 0; i < chunk->count; i++)
 344		if (chunk->owners[i].owner)
 345			ret++;
 346	return ret;
 347}
 348
 349static void untag_chunk(struct audit_chunk *chunk, struct fsnotify_mark *mark)
 350{
 351	struct audit_chunk *new;
 352	int size;
 
 
 
 353
 354	fsnotify_group_lock(audit_tree_group);
 355	/*
 356	 * mark_mutex stabilizes chunk attached to the mark so we can check
 357	 * whether it didn't change while we've dropped hash_lock.
 358	 */
 359	if (!(mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED) ||
 360	    mark_chunk(mark) != chunk)
 361		goto out_mutex;
 362
 363	size = chunk_count_trees(chunk);
 364	if (!size) {
 
 365		spin_lock(&hash_lock);
 366		list_del_init(&chunk->trees);
 
 
 
 367		list_del_rcu(&chunk->hash);
 368		replace_mark_chunk(mark, NULL);
 369		spin_unlock(&hash_lock);
 370		fsnotify_detach_mark(mark);
 371		fsnotify_group_unlock(audit_tree_group);
 372		audit_mark_put_chunk(chunk);
 373		fsnotify_free_mark(mark);
 374		return;
 375	}
 376
 377	new = alloc_chunk(size);
 378	if (!new)
 379		goto out_mutex;
 380
 
 
 
 
 
 
 
 381	spin_lock(&hash_lock);
 382	/*
 383	 * This has to go last when updating chunk as once replace_chunk() is
 384	 * called, new RCU readers can see the new chunk.
 385	 */
 386	replace_chunk(new, chunk);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 387	spin_unlock(&hash_lock);
 388	fsnotify_group_unlock(audit_tree_group);
 389	audit_mark_put_chunk(chunk);
 390	return;
 391
 392out_mutex:
 393	fsnotify_group_unlock(audit_tree_group);
 
 
 
 
 
 
 
 
 
 
 
 
 
 394}
 395
 396/* Call with group->mark_mutex held, releases it */
 397static int create_chunk(struct inode *inode, struct audit_tree *tree)
 398{
 399	struct fsnotify_mark *mark;
 400	struct audit_chunk *chunk = alloc_chunk(1);
 401
 402	if (!chunk) {
 403		fsnotify_group_unlock(audit_tree_group);
 404		return -ENOMEM;
 405	}
 406
 407	mark = alloc_mark();
 408	if (!mark) {
 409		fsnotify_group_unlock(audit_tree_group);
 410		kfree(chunk);
 411		return -ENOMEM;
 412	}
 413
 414	if (fsnotify_add_inode_mark_locked(mark, inode, 0)) {
 415		fsnotify_group_unlock(audit_tree_group);
 416		fsnotify_put_mark(mark);
 417		kfree(chunk);
 418		return -ENOSPC;
 419	}
 420
 
 421	spin_lock(&hash_lock);
 422	if (tree->goner) {
 423		spin_unlock(&hash_lock);
 424		fsnotify_detach_mark(mark);
 425		fsnotify_group_unlock(audit_tree_group);
 426		fsnotify_free_mark(mark);
 427		fsnotify_put_mark(mark);
 428		kfree(chunk);
 429		return 0;
 430	}
 431	replace_mark_chunk(mark, chunk);
 432	chunk->owners[0].index = (1U << 31);
 433	chunk->owners[0].owner = tree;
 434	get_tree(tree);
 435	list_add(&chunk->owners[0].list, &tree->chunks);
 436	if (!tree->root) {
 437		tree->root = chunk;
 438		list_add(&tree->same_root, &chunk->trees);
 439	}
 440	chunk->key = inode_to_key(inode);
 441	/*
 442	 * Inserting into the hash table has to go last as once we do that RCU
 443	 * readers can see the chunk.
 444	 */
 445	insert_hash(chunk);
 446	spin_unlock(&hash_lock);
 447	fsnotify_group_unlock(audit_tree_group);
 448	/*
 449	 * Drop our initial reference. When mark we point to is getting freed,
 450	 * we get notification through ->freeing_mark callback and cleanup
 451	 * chunk pointing to this mark.
 452	 */
 453	fsnotify_put_mark(mark);
 454	return 0;
 455}
 456
 457/* the first tagged inode becomes root of tree */
 458static int tag_chunk(struct inode *inode, struct audit_tree *tree)
 459{
 460	struct fsnotify_mark *mark;
 
 461	struct audit_chunk *chunk, *old;
 462	struct audit_node *p;
 463	int n;
 464
 465	fsnotify_group_lock(audit_tree_group);
 466	mark = fsnotify_find_mark(&inode->i_fsnotify_marks, audit_tree_group);
 467	if (!mark)
 468		return create_chunk(inode, tree);
 469
 470	/*
 471	 * Found mark is guaranteed to be attached and mark_mutex protects mark
 472	 * from getting detached and thus it makes sure there is chunk attached
 473	 * to the mark.
 474	 */
 475	/* are we already there? */
 476	spin_lock(&hash_lock);
 477	old = mark_chunk(mark);
 478	for (n = 0; n < old->count; n++) {
 479		if (old->owners[n].owner == tree) {
 480			spin_unlock(&hash_lock);
 481			fsnotify_group_unlock(audit_tree_group);
 482			fsnotify_put_mark(mark);
 483			return 0;
 484		}
 485	}
 486	spin_unlock(&hash_lock);
 487
 488	chunk = alloc_chunk(old->count + 1);
 489	if (!chunk) {
 490		fsnotify_group_unlock(audit_tree_group);
 491		fsnotify_put_mark(mark);
 492		return -ENOMEM;
 493	}
 494
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 495	spin_lock(&hash_lock);
 
 
 496	if (tree->goner) {
 497		spin_unlock(&hash_lock);
 498		fsnotify_group_unlock(audit_tree_group);
 499		fsnotify_put_mark(mark);
 500		kfree(chunk);
 
 
 
 
 
 
 501		return 0;
 502	}
 503	p = &chunk->owners[chunk->count - 1];
 
 
 
 
 
 
 
 
 
 504	p->index = (chunk->count - 1) | (1U<<31);
 505	p->owner = tree;
 506	get_tree(tree);
 507	list_add(&p->list, &tree->chunks);
 
 
 
 
 508	if (!tree->root) {
 509		tree->root = chunk;
 510		list_add(&tree->same_root, &chunk->trees);
 511	}
 512	/*
 513	 * This has to go last when updating chunk as once replace_chunk() is
 514	 * called, new RCU readers can see the new chunk.
 515	 */
 516	replace_chunk(chunk, old);
 517	spin_unlock(&hash_lock);
 518	fsnotify_group_unlock(audit_tree_group);
 519	fsnotify_put_mark(mark); /* pair to fsnotify_find_mark */
 520	audit_mark_put_chunk(old);
 521
 522	return 0;
 523}
 524
 525static void audit_tree_log_remove_rule(struct audit_context *context,
 526				       struct audit_krule *rule)
 527{
 528	struct audit_buffer *ab;
 529
 530	if (!audit_enabled)
 531		return;
 532	ab = audit_log_start(context, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
 533	if (unlikely(!ab))
 534		return;
 535	audit_log_format(ab, "op=remove_rule dir=");
 536	audit_log_untrustedstring(ab, rule->tree->pathname);
 537	audit_log_key(ab, rule->filterkey);
 538	audit_log_format(ab, " list=%d res=1", rule->listnr);
 539	audit_log_end(ab);
 540}
 541
 542static void kill_rules(struct audit_context *context, struct audit_tree *tree)
 543{
 544	struct audit_krule *rule, *next;
 545	struct audit_entry *entry;
 
 546
 547	list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
 548		entry = container_of(rule, struct audit_entry, rule);
 549
 550		list_del_init(&rule->rlist);
 551		if (rule->tree) {
 552			/* not a half-baked one */
 553			audit_tree_log_remove_rule(context, rule);
 554			if (entry->rule.exe)
 555				audit_remove_mark(entry->rule.exe);
 
 
 
 
 
 556			rule->tree = NULL;
 557			list_del_rcu(&entry->list);
 558			list_del(&entry->rule.list);
 559			call_rcu(&entry->rcu, audit_free_rule_rcu);
 560		}
 561	}
 562}
 563
 564/*
 565 * Remove tree from chunks. If 'tagged' is set, remove tree only from tagged
 566 * chunks. The function expects tagged chunks are all at the beginning of the
 567 * chunks list.
 568 */
 569static void prune_tree_chunks(struct audit_tree *victim, bool tagged)
 570{
 571	spin_lock(&hash_lock);
 572	while (!list_empty(&victim->chunks)) {
 573		struct audit_node *p;
 574		struct audit_chunk *chunk;
 575		struct fsnotify_mark *mark;
 576
 577		p = list_first_entry(&victim->chunks, struct audit_node, list);
 578		/* have we run out of marked? */
 579		if (tagged && !(p->index & (1U<<31)))
 580			break;
 581		chunk = find_chunk(p);
 582		mark = chunk->mark;
 583		remove_chunk_node(chunk, p);
 584		/* Racing with audit_tree_freeing_mark()? */
 585		if (!mark)
 586			continue;
 587		fsnotify_get_mark(mark);
 588		spin_unlock(&hash_lock);
 589
 590		untag_chunk(chunk, mark);
 591		fsnotify_put_mark(mark);
 592
 593		spin_lock(&hash_lock);
 594	}
 595	spin_unlock(&hash_lock);
 596}
 597
 598/*
 599 * finish killing struct audit_tree
 600 */
 601static void prune_one(struct audit_tree *victim)
 602{
 603	prune_tree_chunks(victim, false);
 604	put_tree(victim);
 605}
 606
 607/* trim the uncommitted chunks from tree */
 608
 609static void trim_marked(struct audit_tree *tree)
 610{
 611	struct list_head *p, *q;
 612	spin_lock(&hash_lock);
 613	if (tree->goner) {
 614		spin_unlock(&hash_lock);
 615		return;
 616	}
 617	/* reorder */
 618	for (p = tree->chunks.next; p != &tree->chunks; p = q) {
 619		struct audit_node *node = list_entry(p, struct audit_node, list);
 620		q = p->next;
 621		if (node->index & (1U<<31)) {
 622			list_del_init(p);
 623			list_add(p, &tree->chunks);
 624		}
 625	}
 626	spin_unlock(&hash_lock);
 627
 628	prune_tree_chunks(tree, true);
 
 629
 630	spin_lock(&hash_lock);
 
 
 
 
 
 
 
 631	if (!tree->root && !tree->goner) {
 632		tree->goner = 1;
 633		spin_unlock(&hash_lock);
 634		mutex_lock(&audit_filter_mutex);
 635		kill_rules(audit_context(), tree);
 636		list_del_init(&tree->list);
 637		mutex_unlock(&audit_filter_mutex);
 638		prune_one(tree);
 639	} else {
 640		spin_unlock(&hash_lock);
 641	}
 642}
 643
 644static void audit_schedule_prune(void);
 645
 646/* called with audit_filter_mutex */
 647int audit_remove_tree_rule(struct audit_krule *rule)
 648{
 649	struct audit_tree *tree;
 650	tree = rule->tree;
 651	if (tree) {
 652		spin_lock(&hash_lock);
 653		list_del_init(&rule->rlist);
 654		if (list_empty(&tree->rules) && !tree->goner) {
 655			tree->root = NULL;
 656			list_del_init(&tree->same_root);
 657			tree->goner = 1;
 658			list_move(&tree->list, &prune_list);
 659			rule->tree = NULL;
 660			spin_unlock(&hash_lock);
 661			audit_schedule_prune();
 662			return 1;
 663		}
 664		rule->tree = NULL;
 665		spin_unlock(&hash_lock);
 666		return 1;
 667	}
 668	return 0;
 669}
 670
 671static int compare_root(struct vfsmount *mnt, void *arg)
 672{
 673	return inode_to_key(d_backing_inode(mnt->mnt_root)) ==
 674	       (unsigned long)arg;
 675}
 676
 677void audit_trim_trees(void)
 678{
 679	struct list_head cursor;
 680
 681	mutex_lock(&audit_filter_mutex);
 682	list_add(&cursor, &tree_list);
 683	while (cursor.next != &tree_list) {
 684		struct audit_tree *tree;
 685		struct path path;
 686		struct vfsmount *root_mnt;
 687		struct audit_node *node;
 688		int err;
 689
 690		tree = container_of(cursor.next, struct audit_tree, list);
 691		get_tree(tree);
 692		list_move(&cursor, &tree->list);
 
 693		mutex_unlock(&audit_filter_mutex);
 694
 695		err = kern_path(tree->pathname, 0, &path);
 696		if (err)
 697			goto skip_it;
 698
 699		root_mnt = collect_mounts(&path);
 700		path_put(&path);
 701		if (IS_ERR(root_mnt))
 702			goto skip_it;
 703
 704		spin_lock(&hash_lock);
 705		list_for_each_entry(node, &tree->chunks, list) {
 706			struct audit_chunk *chunk = find_chunk(node);
 707			/* this could be NULL if the watch is dying else where... */
 
 708			node->index |= 1U<<31;
 709			if (iterate_mounts(compare_root,
 710					   (void *)(chunk->key),
 711					   root_mnt))
 712				node->index &= ~(1U<<31);
 713		}
 714		spin_unlock(&hash_lock);
 715		trim_marked(tree);
 
 716		drop_collected_mounts(root_mnt);
 717skip_it:
 718		put_tree(tree);
 719		mutex_lock(&audit_filter_mutex);
 720	}
 721	list_del(&cursor);
 722	mutex_unlock(&audit_filter_mutex);
 723}
 724
 725int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
 726{
 727
 728	if (pathname[0] != '/' ||
 729	    (rule->listnr != AUDIT_FILTER_EXIT &&
 730	     rule->listnr != AUDIT_FILTER_URING_EXIT) ||
 731	    op != Audit_equal ||
 732	    rule->inode_f || rule->watch || rule->tree)
 733		return -EINVAL;
 734	rule->tree = alloc_tree(pathname);
 735	if (!rule->tree)
 736		return -ENOMEM;
 737	return 0;
 738}
 739
 740void audit_put_tree(struct audit_tree *tree)
 741{
 742	put_tree(tree);
 743}
 744
 745static int tag_mount(struct vfsmount *mnt, void *arg)
 746{
 747	return tag_chunk(d_backing_inode(mnt->mnt_root), arg);
 748}
 749
 750/*
 751 * That gets run when evict_chunk() ends up needing to kill audit_tree.
 752 * Runs from a separate thread.
 753 */
 754static int prune_tree_thread(void *unused)
 755{
 756	for (;;) {
 757		if (list_empty(&prune_list)) {
 758			set_current_state(TASK_INTERRUPTIBLE);
 759			schedule();
 760		}
 761
 762		audit_ctl_lock();
 763		mutex_lock(&audit_filter_mutex);
 764
 765		while (!list_empty(&prune_list)) {
 766			struct audit_tree *victim;
 767
 768			victim = list_entry(prune_list.next,
 769					struct audit_tree, list);
 770			list_del_init(&victim->list);
 771
 772			mutex_unlock(&audit_filter_mutex);
 773
 774			prune_one(victim);
 775
 776			mutex_lock(&audit_filter_mutex);
 777		}
 778
 779		mutex_unlock(&audit_filter_mutex);
 780		audit_ctl_unlock();
 781	}
 782	return 0;
 783}
 784
 785static int audit_launch_prune(void)
 786{
 787	if (prune_thread)
 788		return 0;
 789	prune_thread = kthread_run(prune_tree_thread, NULL,
 790				"audit_prune_tree");
 791	if (IS_ERR(prune_thread)) {
 792		pr_err("cannot start thread audit_prune_tree");
 793		prune_thread = NULL;
 794		return -ENOMEM;
 795	}
 796	return 0;
 797}
 798
 799/* called with audit_filter_mutex */
 800int audit_add_tree_rule(struct audit_krule *rule)
 801{
 802	struct audit_tree *seed = rule->tree, *tree;
 803	struct path path;
 804	struct vfsmount *mnt;
 805	int err;
 806
 807	rule->tree = NULL;
 808	list_for_each_entry(tree, &tree_list, list) {
 809		if (!strcmp(seed->pathname, tree->pathname)) {
 810			put_tree(seed);
 811			rule->tree = tree;
 812			list_add(&rule->rlist, &tree->rules);
 813			return 0;
 814		}
 815	}
 816	tree = seed;
 817	list_add(&tree->list, &tree_list);
 818	list_add(&rule->rlist, &tree->rules);
 819	/* do not set rule->tree yet */
 820	mutex_unlock(&audit_filter_mutex);
 821
 822	if (unlikely(!prune_thread)) {
 823		err = audit_launch_prune();
 824		if (err)
 825			goto Err;
 826	}
 827
 828	err = kern_path(tree->pathname, 0, &path);
 829	if (err)
 830		goto Err;
 831	mnt = collect_mounts(&path);
 832	path_put(&path);
 833	if (IS_ERR(mnt)) {
 834		err = PTR_ERR(mnt);
 835		goto Err;
 836	}
 837
 838	get_tree(tree);
 839	err = iterate_mounts(tag_mount, tree, mnt);
 840	drop_collected_mounts(mnt);
 841
 842	if (!err) {
 843		struct audit_node *node;
 844		spin_lock(&hash_lock);
 845		list_for_each_entry(node, &tree->chunks, list)
 846			node->index &= ~(1U<<31);
 847		spin_unlock(&hash_lock);
 848	} else {
 849		trim_marked(tree);
 850		goto Err;
 851	}
 852
 853	mutex_lock(&audit_filter_mutex);
 854	if (list_empty(&rule->rlist)) {
 855		put_tree(tree);
 856		return -ENOENT;
 857	}
 858	rule->tree = tree;
 859	put_tree(tree);
 860
 861	return 0;
 862Err:
 863	mutex_lock(&audit_filter_mutex);
 864	list_del_init(&tree->list);
 865	list_del_init(&tree->rules);
 866	put_tree(tree);
 867	return err;
 868}
 869
 870int audit_tag_tree(char *old, char *new)
 871{
 872	struct list_head cursor, barrier;
 873	int failed = 0;
 874	struct path path1, path2;
 875	struct vfsmount *tagged;
 876	int err;
 877
 878	err = kern_path(new, 0, &path2);
 879	if (err)
 880		return err;
 881	tagged = collect_mounts(&path2);
 882	path_put(&path2);
 883	if (IS_ERR(tagged))
 884		return PTR_ERR(tagged);
 885
 886	err = kern_path(old, 0, &path1);
 887	if (err) {
 888		drop_collected_mounts(tagged);
 889		return err;
 890	}
 891
 892	mutex_lock(&audit_filter_mutex);
 893	list_add(&barrier, &tree_list);
 894	list_add(&cursor, &barrier);
 895
 896	while (cursor.next != &tree_list) {
 897		struct audit_tree *tree;
 898		int good_one = 0;
 899
 900		tree = container_of(cursor.next, struct audit_tree, list);
 901		get_tree(tree);
 902		list_move(&cursor, &tree->list);
 
 903		mutex_unlock(&audit_filter_mutex);
 904
 905		err = kern_path(tree->pathname, 0, &path2);
 906		if (!err) {
 907			good_one = path_is_under(&path1, &path2);
 908			path_put(&path2);
 909		}
 910
 911		if (!good_one) {
 912			put_tree(tree);
 913			mutex_lock(&audit_filter_mutex);
 914			continue;
 915		}
 916
 917		failed = iterate_mounts(tag_mount, tree, tagged);
 918		if (failed) {
 919			put_tree(tree);
 920			mutex_lock(&audit_filter_mutex);
 921			break;
 922		}
 923
 924		mutex_lock(&audit_filter_mutex);
 925		spin_lock(&hash_lock);
 926		if (!tree->goner) {
 927			list_move(&tree->list, &tree_list);
 
 928		}
 929		spin_unlock(&hash_lock);
 930		put_tree(tree);
 931	}
 932
 933	while (barrier.prev != &tree_list) {
 934		struct audit_tree *tree;
 935
 936		tree = container_of(barrier.prev, struct audit_tree, list);
 937		get_tree(tree);
 938		list_move(&tree->list, &barrier);
 
 939		mutex_unlock(&audit_filter_mutex);
 940
 941		if (!failed) {
 942			struct audit_node *node;
 943			spin_lock(&hash_lock);
 944			list_for_each_entry(node, &tree->chunks, list)
 945				node->index &= ~(1U<<31);
 946			spin_unlock(&hash_lock);
 947		} else {
 948			trim_marked(tree);
 949		}
 950
 951		put_tree(tree);
 952		mutex_lock(&audit_filter_mutex);
 953	}
 954	list_del(&barrier);
 955	list_del(&cursor);
 956	mutex_unlock(&audit_filter_mutex);
 957	path_put(&path1);
 958	drop_collected_mounts(tagged);
 959	return failed;
 960}
 961
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 962
 963static void audit_schedule_prune(void)
 964{
 965	wake_up_process(prune_thread);
 966}
 967
 968/*
 969 * ... and that one is done if evict_chunk() decides to delay until the end
 970 * of syscall.  Runs synchronously.
 971 */
 972void audit_kill_trees(struct audit_context *context)
 973{
 974	struct list_head *list = &context->killed_trees;
 975
 976	audit_ctl_lock();
 977	mutex_lock(&audit_filter_mutex);
 978
 979	while (!list_empty(list)) {
 980		struct audit_tree *victim;
 981
 982		victim = list_entry(list->next, struct audit_tree, list);
 983		kill_rules(context, victim);
 984		list_del_init(&victim->list);
 985
 986		mutex_unlock(&audit_filter_mutex);
 987
 988		prune_one(victim);
 989
 990		mutex_lock(&audit_filter_mutex);
 991	}
 992
 993	mutex_unlock(&audit_filter_mutex);
 994	audit_ctl_unlock();
 995}
 996
 997/*
 998 *  Here comes the stuff asynchronous to auditctl operations
 999 */
1000
1001static void evict_chunk(struct audit_chunk *chunk)
1002{
1003	struct audit_tree *owner;
1004	struct list_head *postponed = audit_killed_trees();
1005	int need_prune = 0;
1006	int n;
1007
 
 
 
 
1008	mutex_lock(&audit_filter_mutex);
1009	spin_lock(&hash_lock);
1010	while (!list_empty(&chunk->trees)) {
1011		owner = list_entry(chunk->trees.next,
1012				   struct audit_tree, same_root);
1013		owner->goner = 1;
1014		owner->root = NULL;
1015		list_del_init(&owner->same_root);
1016		spin_unlock(&hash_lock);
1017		if (!postponed) {
1018			kill_rules(audit_context(), owner);
1019			list_move(&owner->list, &prune_list);
1020			need_prune = 1;
1021		} else {
1022			list_move(&owner->list, postponed);
1023		}
1024		spin_lock(&hash_lock);
1025	}
1026	list_del_rcu(&chunk->hash);
1027	for (n = 0; n < chunk->count; n++)
1028		list_del_init(&chunk->owners[n].list);
1029	spin_unlock(&hash_lock);
1030	mutex_unlock(&audit_filter_mutex);
1031	if (need_prune)
1032		audit_schedule_prune();
 
1033}
1034
1035static int audit_tree_handle_event(struct fsnotify_mark *mark, u32 mask,
1036				   struct inode *inode, struct inode *dir,
1037				   const struct qstr *file_name, u32 cookie)
 
1038{
1039	return 0;
 
1040}
1041
1042static void audit_tree_freeing_mark(struct fsnotify_mark *mark,
1043				    struct fsnotify_group *group)
1044{
1045	struct audit_chunk *chunk;
1046
1047	fsnotify_group_lock(mark->group);
1048	spin_lock(&hash_lock);
1049	chunk = mark_chunk(mark);
1050	replace_mark_chunk(mark, NULL);
1051	spin_unlock(&hash_lock);
1052	fsnotify_group_unlock(mark->group);
1053	if (chunk) {
1054		evict_chunk(chunk);
1055		audit_mark_put_chunk(chunk);
1056	}
1057
1058	/*
1059	 * We are guaranteed to have at least one reference to the mark from
1060	 * either the inode or the caller of fsnotify_destroy_mark().
1061	 */
1062	BUG_ON(refcount_read(&mark->refcnt) < 1);
 
1063}
1064
1065static const struct fsnotify_ops audit_tree_ops = {
1066	.handle_inode_event = audit_tree_handle_event,
 
 
 
1067	.freeing_mark = audit_tree_freeing_mark,
1068	.free_mark = audit_tree_destroy_watch,
1069};
1070
1071static int __init audit_tree_init(void)
1072{
1073	int i;
1074
1075	audit_tree_mark_cachep = KMEM_CACHE(audit_tree_mark, SLAB_PANIC);
1076
1077	audit_tree_group = fsnotify_alloc_group(&audit_tree_ops, 0);
1078	if (IS_ERR(audit_tree_group))
1079		audit_panic("cannot initialize fsnotify group for rectree watches");
1080
1081	for (i = 0; i < HASH_SIZE; i++)
1082		INIT_LIST_HEAD(&chunk_hash_heads[i]);
1083
1084	return 0;
1085}
1086__initcall(audit_tree_init);