audit_tree.c 23.9 KB
Newer Older
1
// SPDX-License-Identifier: GPL-2.0
Al Viro's avatar
Al Viro committed
2
#include "audit.h"
3
#include <linux/fsnotify_backend.h>
Al Viro's avatar
Al Viro committed
4 5
#include <linux/namei.h>
#include <linux/mount.h>
6
#include <linux/kthread.h>
7
#include <linux/refcount.h>
8
#include <linux/slab.h>
Al Viro's avatar
Al Viro committed
9 10 11 12 13

struct audit_tree;
struct audit_chunk;

struct audit_tree {
14
	refcount_t count;
Al Viro's avatar
Al Viro committed
15 16 17 18 19 20 21 22 23 24 25 26
	int goner;
	struct audit_chunk *root;
	struct list_head chunks;
	struct list_head rules;
	struct list_head list;
	struct list_head same_root;
	struct rcu_head head;
	char pathname[];
};

struct audit_chunk {
	struct list_head hash;
27
	struct fsnotify_mark mark;
Al Viro's avatar
Al Viro committed
28 29 30
	struct list_head trees;		/* with root here */
	int dead;
	int count;
31
	atomic_long_t refs;
Al Viro's avatar
Al Viro committed
32 33 34 35 36 37 38 39 40 41
	struct rcu_head head;
	struct node {
		struct list_head list;
		struct audit_tree *owner;
		unsigned index;		/* index; upper bit indicates 'will prune' */
	} owners[];
};

static LIST_HEAD(tree_list);
static LIST_HEAD(prune_list);
42
static struct task_struct *prune_thread;
Al Viro's avatar
Al Viro committed
43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64

/*
 * One struct chunk is attached to each inode of interest.
 * We replace struct chunk on tagging/untagging.
 * Rules have pointer to struct audit_tree.
 * Rules have struct list_head rlist forming a list of rules over
 * the same tree.
 * References to struct chunk are collected at audit_inode{,_child}()
 * time and used in AUDIT_TREE rule matching.
 * These references are dropped at the same time we are calling
 * audit_free_names(), etc.
 *
 * Cyclic lists galore:
 * tree.chunks anchors chunk.owners[].list			hash_lock
 * tree.rules anchors rule.rlist				audit_filter_mutex
 * chunk.trees anchors tree.same_root				hash_lock
 * chunk.hash is a hash with middle bits of watch.inode as
 * a hash function.						RCU, hash_lock
 *
 * tree is refcounted; one reference for "some rules on rules_list refer to
 * it", one for each chunk with pointer to it.
 *
65
 * chunk is refcounted by embedded fsnotify_mark + .refs (non-zero refcount
66
 * of watch contributes 1 to .refs).
Al Viro's avatar
Al Viro committed
67 68 69 70 71 72 73
 *
 * node.index allows to get from node.list to containing chunk.
 * MSB of that sucker is stolen to mark taggings that we might have to
 * revert - several operations have very unpleasant cleanup logics and
 * that makes a difference.  Some.
 */

74
static struct fsnotify_group *audit_tree_group;
Al Viro's avatar
Al Viro committed
75 76 77 78 79 80 81

static struct audit_tree *alloc_tree(const char *s)
{
	struct audit_tree *tree;

	tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
	if (tree) {
82
		refcount_set(&tree->count, 1);
Al Viro's avatar
Al Viro committed
83 84 85 86 87 88 89 90 91 92 93 94 95
		tree->goner = 0;
		INIT_LIST_HEAD(&tree->chunks);
		INIT_LIST_HEAD(&tree->rules);
		INIT_LIST_HEAD(&tree->list);
		INIT_LIST_HEAD(&tree->same_root);
		tree->root = NULL;
		strcpy(tree->pathname, s);
	}
	return tree;
}

static inline void get_tree(struct audit_tree *tree)
{
96
	refcount_inc(&tree->count);
Al Viro's avatar
Al Viro committed
97 98 99 100
}

static inline void put_tree(struct audit_tree *tree)
{
101
	if (refcount_dec_and_test(&tree->count))
102
		kfree_rcu(tree, head);
Al Viro's avatar
Al Viro committed
103 104 105 106 107 108 109 110
}

/* to avoid bringing the entire thing in audit.h */
const char *audit_tree_path(struct audit_tree *tree)
{
	return tree->pathname;
}

111
static void free_chunk(struct audit_chunk *chunk)
Al Viro's avatar
Al Viro committed
112 113 114 115 116 117 118 119 120 121
{
	int i;

	for (i = 0; i < chunk->count; i++) {
		if (chunk->owners[i].owner)
			put_tree(chunk->owners[i].owner);
	}
	kfree(chunk);
}

122
void audit_put_chunk(struct audit_chunk *chunk)
Al Viro's avatar
Al Viro committed
123
{
124 125
	if (atomic_long_dec_and_test(&chunk->refs))
		free_chunk(chunk);
Al Viro's avatar
Al Viro committed
126 127
}

128
static void __put_chunk(struct rcu_head *rcu)
Al Viro's avatar
Al Viro committed
129
{
130 131
	struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
	audit_put_chunk(chunk);
Al Viro's avatar
Al Viro committed
132 133
}

134
static void audit_tree_destroy_watch(struct fsnotify_mark *entry)
135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158
{
	struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
	call_rcu(&chunk->head, __put_chunk);
}

static struct audit_chunk *alloc_chunk(int count)
{
	struct audit_chunk *chunk;
	size_t size;
	int i;

	size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
	chunk = kzalloc(size, GFP_KERNEL);
	if (!chunk)
		return NULL;

	INIT_LIST_HEAD(&chunk->hash);
	INIT_LIST_HEAD(&chunk->trees);
	chunk->count = count;
	atomic_long_set(&chunk->refs, 1);
	for (i = 0; i < count; i++) {
		INIT_LIST_HEAD(&chunk->owners[i].list);
		chunk->owners[i].index = i;
	}
159
	fsnotify_init_mark(&chunk->mark, audit_tree_group);
Miklos Szeredi's avatar
Miklos Szeredi committed
160
	chunk->mark.mask = FS_IN_IGNORED;
161 162 163
	return chunk;
}

Al Viro's avatar
Al Viro committed
164 165 166 167
enum {HASH_SIZE = 128};
static struct list_head chunk_hash_heads[HASH_SIZE];
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);

Jan Kara's avatar
Jan Kara committed
168 169
/* Function to return search key in our hash from inode. */
static unsigned long inode_to_key(const struct inode *inode)
Al Viro's avatar
Al Viro committed
170
{
Jan Kara's avatar
Jan Kara committed
171 172 173 174 175 176 177
	return (unsigned long)inode;
}

/*
 * Function to return search key in our hash from chunk. Key 0 is special and
 * should never be present in the hash.
 */
178
static unsigned long chunk_to_key(struct audit_chunk *chunk)
179
{
180 181 182 183 184
	/*
	 * We have a reference to the mark so it should be attached to a
	 * connector.
	 */
	if (WARN_ON_ONCE(!chunk->mark.connector))
185 186 187 188
		return 0;
	return (unsigned long)chunk->mark.connector->inode;
}

Jan Kara's avatar
Jan Kara committed
189 190 191
static inline struct list_head *chunk_hash(unsigned long key)
{
	unsigned long n = key / L1_CACHE_BYTES;
Al Viro's avatar
Al Viro committed
192 193 194
	return chunk_hash_heads + n % HASH_SIZE;
}

195
/* hash_lock & entry->lock is held by caller */
Al Viro's avatar
Al Viro committed
196 197
static void insert_hash(struct audit_chunk *chunk)
{
198
	unsigned long key = chunk_to_key(chunk);
199 200
	struct list_head *list;

201
	if (!(chunk->mark.flags & FSNOTIFY_MARK_FLAG_ATTACHED))
202
		return;
Jan Kara's avatar
Jan Kara committed
203
	list = chunk_hash(key);
Al Viro's avatar
Al Viro committed
204 205 206 207 208 209
	list_add_rcu(&chunk->hash, list);
}

/* called under rcu_read_lock */
struct audit_chunk *audit_tree_lookup(const struct inode *inode)
{
Jan Kara's avatar
Jan Kara committed
210 211
	unsigned long key = inode_to_key(inode);
	struct list_head *list = chunk_hash(key);
212
	struct audit_chunk *p;
Al Viro's avatar
Al Viro committed
213

214
	list_for_each_entry_rcu(p, list, hash) {
Jan Kara's avatar
Jan Kara committed
215
		if (chunk_to_key(p) == key) {
216
			atomic_long_inc(&p->refs);
Al Viro's avatar
Al Viro committed
217 218 219 220 221 222
			return p;
		}
	}
	return NULL;
}

223
bool audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
Al Viro's avatar
Al Viro committed
224 225 226 227
{
	int n;
	for (n = 0; n < chunk->count; n++)
		if (chunk->owners[n].owner == tree)
228 229
			return true;
	return false;
Al Viro's avatar
Al Viro committed
230 231 232 233
}

/* tagging and untagging inodes with trees */

234 235 236 237 238 239 240 241
static struct audit_chunk *find_chunk(struct node *p)
{
	int index = p->index & ~(1U<<31);
	p -= index;
	return container_of(p, struct audit_chunk, owners[0]);
}

static void untag_chunk(struct node *p)
Al Viro's avatar
Al Viro committed
242
{
243
	struct audit_chunk *chunk = find_chunk(p);
244
	struct fsnotify_mark *entry = &chunk->mark;
245
	struct audit_chunk *new = NULL;
Al Viro's avatar
Al Viro committed
246 247 248 249
	struct audit_tree *owner;
	int size = chunk->count - 1;
	int i, j;

250
	fsnotify_get_mark(entry);
251 252 253

	spin_unlock(&hash_lock);

254 255 256
	if (size)
		new = alloc_chunk(size);

Jan Kara's avatar
Jan Kara committed
257
	mutex_lock(&entry->group->mark_mutex);
258
	spin_lock(&entry->lock);
259 260 261 262
	/*
	 * mark_mutex protects mark from getting detached and thus also from
	 * mark->connector->inode getting NULL.
	 */
263
	if (chunk->dead || !(entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) {
264
		spin_unlock(&entry->lock);
Jan Kara's avatar
Jan Kara committed
265
		mutex_unlock(&entry->group->mark_mutex);
266
		if (new)
267
			fsnotify_put_mark(&new->mark);
268
		goto out;
Al Viro's avatar
Al Viro committed
269 270 271 272 273 274 275 276 277 278 279 280 281
	}

	owner = p->owner;

	if (!size) {
		chunk->dead = 1;
		spin_lock(&hash_lock);
		list_del_init(&chunk->trees);
		if (owner->root == chunk)
			owner->root = NULL;
		list_del_init(&p->list);
		list_del_rcu(&chunk->hash);
		spin_unlock(&hash_lock);
282
		spin_unlock(&entry->lock);
Jan Kara's avatar
Jan Kara committed
283
		mutex_unlock(&entry->group->mark_mutex);
284
		fsnotify_destroy_mark(entry, audit_tree_group);
285
		goto out;
Al Viro's avatar
Al Viro committed
286 287 288 289
	}

	if (!new)
		goto Fallback;
290

291
	if (fsnotify_add_mark_locked(&new->mark, entry->connector->inode,
Jan Kara's avatar
Jan Kara committed
292
				     NULL, 1)) {
293
		fsnotify_put_mark(&new->mark);
Al Viro's avatar
Al Viro committed
294 295 296 297 298 299 300 301 302 303 304
		goto Fallback;
	}

	chunk->dead = 1;
	spin_lock(&hash_lock);
	list_replace_init(&chunk->trees, &new->trees);
	if (owner->root == chunk) {
		list_del_init(&owner->same_root);
		owner->root = NULL;
	}

305
	for (i = j = 0; j <= size; i++, j++) {
Al Viro's avatar
Al Viro committed
306 307 308 309 310 311 312 313 314 315 316 317
		struct audit_tree *s;
		if (&chunk->owners[j] == p) {
			list_del_init(&p->list);
			i--;
			continue;
		}
		s = chunk->owners[j].owner;
		new->owners[i].owner = s;
		new->owners[i].index = chunk->owners[j].index - j + i;
		if (!s) /* result of earlier fallback */
			continue;
		get_tree(s);
318
		list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
Al Viro's avatar
Al Viro committed
319 320 321 322 323 324
	}

	list_replace_rcu(&chunk->hash, &new->hash);
	list_for_each_entry(owner, &new->trees, same_root)
		owner->root = new;
	spin_unlock(&hash_lock);
325
	spin_unlock(&entry->lock);
Jan Kara's avatar
Jan Kara committed
326
	mutex_unlock(&entry->group->mark_mutex);
327
	fsnotify_destroy_mark(entry, audit_tree_group);
328
	fsnotify_put_mark(&new->mark);	/* drop initial reference */
329
	goto out;
Al Viro's avatar
Al Viro committed
330 331 332 333 334 335 336 337 338 339 340 341

Fallback:
	// do the best we can
	spin_lock(&hash_lock);
	if (owner->root == chunk) {
		list_del_init(&owner->same_root);
		owner->root = NULL;
	}
	list_del_init(&p->list);
	p->owner = NULL;
	put_tree(owner);
	spin_unlock(&hash_lock);
342
	spin_unlock(&entry->lock);
Jan Kara's avatar
Jan Kara committed
343
	mutex_unlock(&entry->group->mark_mutex);
344
out:
345
	fsnotify_put_mark(entry);
346
	spin_lock(&hash_lock);
Al Viro's avatar
Al Viro committed
347 348 349 350
}

static int create_chunk(struct inode *inode, struct audit_tree *tree)
{
351
	struct fsnotify_mark *entry;
Al Viro's avatar
Al Viro committed
352 353 354 355
	struct audit_chunk *chunk = alloc_chunk(1);
	if (!chunk)
		return -ENOMEM;

356
	entry = &chunk->mark;
357
	if (fsnotify_add_mark(entry, inode, NULL, 0)) {
358
		fsnotify_put_mark(entry);
Al Viro's avatar
Al Viro committed
359 360 361
		return -ENOSPC;
	}

362
	spin_lock(&entry->lock);
Al Viro's avatar
Al Viro committed
363 364 365 366
	spin_lock(&hash_lock);
	if (tree->goner) {
		spin_unlock(&hash_lock);
		chunk->dead = 1;
367
		spin_unlock(&entry->lock);
368
		fsnotify_destroy_mark(entry, audit_tree_group);
369
		fsnotify_put_mark(entry);
Al Viro's avatar
Al Viro committed
370 371 372 373 374 375 376 377 378 379 380 381
		return 0;
	}
	chunk->owners[0].index = (1U << 31);
	chunk->owners[0].owner = tree;
	get_tree(tree);
	list_add(&chunk->owners[0].list, &tree->chunks);
	if (!tree->root) {
		tree->root = chunk;
		list_add(&tree->same_root, &chunk->trees);
	}
	insert_hash(chunk);
	spin_unlock(&hash_lock);
382
	spin_unlock(&entry->lock);
383
	fsnotify_put_mark(entry);	/* drop initial reference */
Al Viro's avatar
Al Viro committed
384 385 386 387 388 389
	return 0;
}

/* the first tagged inode becomes root of tree */
static int tag_chunk(struct inode *inode, struct audit_tree *tree)
{
390
	struct fsnotify_mark *old_entry, *chunk_entry;
Al Viro's avatar
Al Viro committed
391 392 393 394 395
	struct audit_tree *owner;
	struct audit_chunk *chunk, *old;
	struct node *p;
	int n;

396 397
	old_entry = fsnotify_find_mark(&inode->i_fsnotify_marks,
				       audit_tree_group);
398
	if (!old_entry)
Al Viro's avatar
Al Viro committed
399 400
		return create_chunk(inode, tree);

401
	old = container_of(old_entry, struct audit_chunk, mark);
Al Viro's avatar
Al Viro committed
402 403 404 405 406 407

	/* are we already there? */
	spin_lock(&hash_lock);
	for (n = 0; n < old->count; n++) {
		if (old->owners[n].owner == tree) {
			spin_unlock(&hash_lock);
408
			fsnotify_put_mark(old_entry);
Al Viro's avatar
Al Viro committed
409 410 411 412 413 414
			return 0;
		}
	}
	spin_unlock(&hash_lock);

	chunk = alloc_chunk(old->count + 1);
415
	if (!chunk) {
416
		fsnotify_put_mark(old_entry);
Al Viro's avatar
Al Viro committed
417
		return -ENOMEM;
418
	}
Al Viro's avatar
Al Viro committed
419

420 421
	chunk_entry = &chunk->mark;

Jan Kara's avatar
Jan Kara committed
422
	mutex_lock(&old_entry->group->mark_mutex);
423
	spin_lock(&old_entry->lock);
424 425 426 427
	/*
	 * mark_mutex protects mark from getting detached and thus also from
	 * mark->connector->inode getting NULL.
	 */
428
	if (!(old_entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) {
429 430
		/* old_entry is being shot, lets just lie */
		spin_unlock(&old_entry->lock);
Jan Kara's avatar
Jan Kara committed
431
		mutex_unlock(&old_entry->group->mark_mutex);
432
		fsnotify_put_mark(old_entry);
433
		fsnotify_put_mark(&chunk->mark);
434 435 436
		return -ENOENT;
	}

437
	if (fsnotify_add_mark_locked(chunk_entry,
438
			     old_entry->connector->inode, NULL, 1)) {
439
		spin_unlock(&old_entry->lock);
Jan Kara's avatar
Jan Kara committed
440
		mutex_unlock(&old_entry->group->mark_mutex);
441
		fsnotify_put_mark(chunk_entry);
442
		fsnotify_put_mark(old_entry);
Al Viro's avatar
Al Viro committed
443 444
		return -ENOSPC;
	}
445 446 447

	/* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
	spin_lock(&chunk_entry->lock);
Al Viro's avatar
Al Viro committed
448
	spin_lock(&hash_lock);
449 450

	/* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
Al Viro's avatar
Al Viro committed
451 452 453
	if (tree->goner) {
		spin_unlock(&hash_lock);
		chunk->dead = 1;
454 455
		spin_unlock(&chunk_entry->lock);
		spin_unlock(&old_entry->lock);
Jan Kara's avatar
Jan Kara committed
456
		mutex_unlock(&old_entry->group->mark_mutex);
457

458
		fsnotify_destroy_mark(chunk_entry, audit_tree_group);
459 460 461

		fsnotify_put_mark(chunk_entry);
		fsnotify_put_mark(old_entry);
Al Viro's avatar
Al Viro committed
462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486
		return 0;
	}
	list_replace_init(&old->trees, &chunk->trees);
	for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
		struct audit_tree *s = old->owners[n].owner;
		p->owner = s;
		p->index = old->owners[n].index;
		if (!s) /* result of fallback in untag */
			continue;
		get_tree(s);
		list_replace_init(&old->owners[n].list, &p->list);
	}
	p->index = (chunk->count - 1) | (1U<<31);
	p->owner = tree;
	get_tree(tree);
	list_add(&p->list, &tree->chunks);
	list_replace_rcu(&old->hash, &chunk->hash);
	list_for_each_entry(owner, &chunk->trees, same_root)
		owner->root = chunk;
	old->dead = 1;
	if (!tree->root) {
		tree->root = chunk;
		list_add(&tree->same_root, &chunk->trees);
	}
	spin_unlock(&hash_lock);
487 488
	spin_unlock(&chunk_entry->lock);
	spin_unlock(&old_entry->lock);
Jan Kara's avatar
Jan Kara committed
489
	mutex_unlock(&old_entry->group->mark_mutex);
490
	fsnotify_destroy_mark(old_entry, audit_tree_group);
491
	fsnotify_put_mark(chunk_entry);	/* drop initial reference */
492
	fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
Al Viro's avatar
Al Viro committed
493 494 495
	return 0;
}

496
static void audit_tree_log_remove_rule(struct audit_krule *rule)
497 498 499 500 501 502
{
	struct audit_buffer *ab;

	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
	if (unlikely(!ab))
		return;
503
	audit_log_format(ab, "op=remove_rule");
504 505 506 507 508 509 510
	audit_log_format(ab, " dir=");
	audit_log_untrustedstring(ab, rule->tree->pathname);
	audit_log_key(ab, rule->filterkey);
	audit_log_format(ab, " list=%d res=1", rule->listnr);
	audit_log_end(ab);
}

Al Viro's avatar
Al Viro committed
511 512 513 514 515 516 517 518 519 520 521
static void kill_rules(struct audit_tree *tree)
{
	struct audit_krule *rule, *next;
	struct audit_entry *entry;

	list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
		entry = container_of(rule, struct audit_entry, rule);

		list_del_init(&rule->rlist);
		if (rule->tree) {
			/* not a half-baked one */
522
			audit_tree_log_remove_rule(rule);
523 524
			if (entry->rule.exe)
				audit_remove_mark(entry->rule.exe);
Al Viro's avatar
Al Viro committed
525 526
			rule->tree = NULL;
			list_del_rcu(&entry->list);
Al Viro's avatar
Al Viro committed
527
			list_del(&entry->rule.list);
Al Viro's avatar
Al Viro committed
528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543
			call_rcu(&entry->rcu, audit_free_rule_rcu);
		}
	}
}

/*
 * finish killing struct audit_tree
 */
static void prune_one(struct audit_tree *victim)
{
	spin_lock(&hash_lock);
	while (!list_empty(&victim->chunks)) {
		struct node *p;

		p = list_entry(victim->chunks.next, struct node, list);

544
		untag_chunk(p);
Al Viro's avatar
Al Viro committed
545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578
	}
	spin_unlock(&hash_lock);
	put_tree(victim);
}

/* trim the uncommitted chunks from tree */

static void trim_marked(struct audit_tree *tree)
{
	struct list_head *p, *q;
	spin_lock(&hash_lock);
	if (tree->goner) {
		spin_unlock(&hash_lock);
		return;
	}
	/* reorder */
	for (p = tree->chunks.next; p != &tree->chunks; p = q) {
		struct node *node = list_entry(p, struct node, list);
		q = p->next;
		if (node->index & (1U<<31)) {
			list_del_init(p);
			list_add(p, &tree->chunks);
		}
	}

	while (!list_empty(&tree->chunks)) {
		struct node *node;

		node = list_entry(tree->chunks.next, struct node, list);

		/* have we run out of marked? */
		if (!(node->index & (1U<<31)))
			break;

579
		untag_chunk(node);
Al Viro's avatar
Al Viro committed
580 581 582 583 584 585 586 587 588 589 590 591 592 593
	}
	if (!tree->root && !tree->goner) {
		tree->goner = 1;
		spin_unlock(&hash_lock);
		mutex_lock(&audit_filter_mutex);
		kill_rules(tree);
		list_del_init(&tree->list);
		mutex_unlock(&audit_filter_mutex);
		prune_one(tree);
	} else {
		spin_unlock(&hash_lock);
	}
}

594 595
static void audit_schedule_prune(void);

Al Viro's avatar
Al Viro committed
596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620
/* called with audit_filter_mutex */
int audit_remove_tree_rule(struct audit_krule *rule)
{
	struct audit_tree *tree;
	tree = rule->tree;
	if (tree) {
		spin_lock(&hash_lock);
		list_del_init(&rule->rlist);
		if (list_empty(&tree->rules) && !tree->goner) {
			tree->root = NULL;
			list_del_init(&tree->same_root);
			tree->goner = 1;
			list_move(&tree->list, &prune_list);
			rule->tree = NULL;
			spin_unlock(&hash_lock);
			audit_schedule_prune();
			return 1;
		}
		rule->tree = NULL;
		spin_unlock(&hash_lock);
		return 1;
	}
	return 0;
}

Al Viro's avatar
Al Viro committed
621 622
static int compare_root(struct vfsmount *mnt, void *arg)
{
Jan Kara's avatar
Jan Kara committed
623 624
	return inode_to_key(d_backing_inode(mnt->mnt_root)) ==
	       (unsigned long)arg;
Al Viro's avatar
Al Viro committed
625 626
}

Al Viro's avatar
Al Viro committed
627 628 629 630 631 632 633 634
void audit_trim_trees(void)
{
	struct list_head cursor;

	mutex_lock(&audit_filter_mutex);
	list_add(&cursor, &tree_list);
	while (cursor.next != &tree_list) {
		struct audit_tree *tree;
635
		struct path path;
Al Viro's avatar
Al Viro committed
636 637 638 639 640 641 642 643 644 645
		struct vfsmount *root_mnt;
		struct node *node;
		int err;

		tree = container_of(cursor.next, struct audit_tree, list);
		get_tree(tree);
		list_del(&cursor);
		list_add(&cursor, &tree->list);
		mutex_unlock(&audit_filter_mutex);

646
		err = kern_path(tree->pathname, 0, &path);
Al Viro's avatar
Al Viro committed
647 648 649
		if (err)
			goto skip_it;

650
		root_mnt = collect_mounts(&path);
651
		path_put(&path);
652
		if (IS_ERR(root_mnt))
Al Viro's avatar
Al Viro committed
653 654 655 656
			goto skip_it;

		spin_lock(&hash_lock);
		list_for_each_entry(node, &tree->chunks, list) {
657
			struct audit_chunk *chunk = find_chunk(node);
Lucas De Marchi's avatar
Lucas De Marchi committed
658
			/* this could be NULL if the watch is dying else where... */
Al Viro's avatar
Al Viro committed
659
			node->index |= 1U<<31;
Jan Kara's avatar
Jan Kara committed
660 661 662
			if (iterate_mounts(compare_root,
					   (void *)chunk_to_key(chunk),
					   root_mnt))
Al Viro's avatar
Al Viro committed
663
				node->index &= ~(1U<<31);
Al Viro's avatar
Al Viro committed
664 665 666 667 668
		}
		spin_unlock(&hash_lock);
		trim_marked(tree);
		drop_collected_mounts(root_mnt);
skip_it:
669
		put_tree(tree);
Al Viro's avatar
Al Viro committed
670 671 672 673 674 675 676 677 678 679 680
		mutex_lock(&audit_filter_mutex);
	}
	list_del(&cursor);
	mutex_unlock(&audit_filter_mutex);
}

int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
{

	if (pathname[0] != '/' ||
	    rule->listnr != AUDIT_FILTER_EXIT ||
681
	    op != Audit_equal ||
Al Viro's avatar
Al Viro committed
682 683 684 685 686 687 688 689 690 691 692 693 694
	    rule->inode_f || rule->watch || rule->tree)
		return -EINVAL;
	rule->tree = alloc_tree(pathname);
	if (!rule->tree)
		return -ENOMEM;
	return 0;
}

void audit_put_tree(struct audit_tree *tree)
{
	put_tree(tree);
}

Al Viro's avatar
Al Viro committed
695 696
static int tag_mount(struct vfsmount *mnt, void *arg)
{
697
	return tag_chunk(d_backing_inode(mnt->mnt_root), arg);
Al Viro's avatar
Al Viro committed
698 699
}

700 701 702 703 704 705 706
/*
 * That gets run when evict_chunk() ends up needing to kill audit_tree.
 * Runs from a separate thread.
 */
static int prune_tree_thread(void *unused)
{
	for (;;) {
707 708
		if (list_empty(&prune_list)) {
			set_current_state(TASK_INTERRUPTIBLE);
709
			schedule();
710
		}
711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738

		mutex_lock(&audit_cmd_mutex);
		mutex_lock(&audit_filter_mutex);

		while (!list_empty(&prune_list)) {
			struct audit_tree *victim;

			victim = list_entry(prune_list.next,
					struct audit_tree, list);
			list_del_init(&victim->list);

			mutex_unlock(&audit_filter_mutex);

			prune_one(victim);

			mutex_lock(&audit_filter_mutex);
		}

		mutex_unlock(&audit_filter_mutex);
		mutex_unlock(&audit_cmd_mutex);
	}
	return 0;
}

static int audit_launch_prune(void)
{
	if (prune_thread)
		return 0;
739
	prune_thread = kthread_run(prune_tree_thread, NULL,
740 741 742 743 744 745
				"audit_prune_tree");
	if (IS_ERR(prune_thread)) {
		pr_err("cannot start thread audit_prune_tree");
		prune_thread = NULL;
		return -ENOMEM;
	}
746
	return 0;
747 748
}

Al Viro's avatar
Al Viro committed
749 750 751 752
/* called with audit_filter_mutex */
int audit_add_tree_rule(struct audit_krule *rule)
{
	struct audit_tree *seed = rule->tree, *tree;
753
	struct path path;
Al Viro's avatar
Al Viro committed
754
	struct vfsmount *mnt;
Al Viro's avatar
Al Viro committed
755 756
	int err;

757
	rule->tree = NULL;
Al Viro's avatar
Al Viro committed
758 759 760 761 762 763 764 765 766 767 768 769 770 771
	list_for_each_entry(tree, &tree_list, list) {
		if (!strcmp(seed->pathname, tree->pathname)) {
			put_tree(seed);
			rule->tree = tree;
			list_add(&rule->rlist, &tree->rules);
			return 0;
		}
	}
	tree = seed;
	list_add(&tree->list, &tree_list);
	list_add(&rule->rlist, &tree->rules);
	/* do not set rule->tree yet */
	mutex_unlock(&audit_filter_mutex);

772 773 774 775 776 777
	if (unlikely(!prune_thread)) {
		err = audit_launch_prune();
		if (err)
			goto Err;
	}

778
	err = kern_path(tree->pathname, 0, &path);
Al Viro's avatar
Al Viro committed
779 780
	if (err)
		goto Err;
781
	mnt = collect_mounts(&path);
782
	path_put(&path);
783 784
	if (IS_ERR(mnt)) {
		err = PTR_ERR(mnt);
Al Viro's avatar
Al Viro committed
785 786 787 788
		goto Err;
	}

	get_tree(tree);
Al Viro's avatar
Al Viro committed
789
	err = iterate_mounts(tag_mount, tree, mnt);
Al Viro's avatar
Al Viro committed
790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823
	drop_collected_mounts(mnt);

	if (!err) {
		struct node *node;
		spin_lock(&hash_lock);
		list_for_each_entry(node, &tree->chunks, list)
			node->index &= ~(1U<<31);
		spin_unlock(&hash_lock);
	} else {
		trim_marked(tree);
		goto Err;
	}

	mutex_lock(&audit_filter_mutex);
	if (list_empty(&rule->rlist)) {
		put_tree(tree);
		return -ENOENT;
	}
	rule->tree = tree;
	put_tree(tree);

	return 0;
Err:
	mutex_lock(&audit_filter_mutex);
	list_del_init(&tree->list);
	list_del_init(&tree->rules);
	put_tree(tree);
	return err;
}

int audit_tag_tree(char *old, char *new)
{
	struct list_head cursor, barrier;
	int failed = 0;
824
	struct path path1, path2;
Al Viro's avatar
Al Viro committed
825 826 827
	struct vfsmount *tagged;
	int err;

828
	err = kern_path(new, 0, &path2);
Al Viro's avatar
Al Viro committed
829 830
	if (err)
		return err;
831 832
	tagged = collect_mounts(&path2);
	path_put(&path2);
833 834
	if (IS_ERR(tagged))
		return PTR_ERR(tagged);
Al Viro's avatar
Al Viro committed
835

836
	err = kern_path(old, 0, &path1);
Al Viro's avatar
Al Viro committed
837 838 839 840 841 842 843 844 845 846 847
	if (err) {
		drop_collected_mounts(tagged);
		return err;
	}

	mutex_lock(&audit_filter_mutex);
	list_add(&barrier, &tree_list);
	list_add(&cursor, &barrier);

	while (cursor.next != &tree_list) {
		struct audit_tree *tree;
848
		int good_one = 0;
Al Viro's avatar
Al Viro committed
849 850 851 852 853 854 855

		tree = container_of(cursor.next, struct audit_tree, list);
		get_tree(tree);
		list_del(&cursor);
		list_add(&cursor, &tree->list);
		mutex_unlock(&audit_filter_mutex);

856 857 858 859
		err = kern_path(tree->pathname, 0, &path2);
		if (!err) {
			good_one = path_is_under(&path1, &path2);
			path_put(&path2);
Al Viro's avatar
Al Viro committed
860 861
		}

862
		if (!good_one) {
Al Viro's avatar
Al Viro committed
863 864 865 866 867
			put_tree(tree);
			mutex_lock(&audit_filter_mutex);
			continue;
		}

Al Viro's avatar
Al Viro committed
868
		failed = iterate_mounts(tag_mount, tree, tagged);
Al Viro's avatar
Al Viro committed
869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909
		if (failed) {
			put_tree(tree);
			mutex_lock(&audit_filter_mutex);
			break;
		}

		mutex_lock(&audit_filter_mutex);
		spin_lock(&hash_lock);
		if (!tree->goner) {
			list_del(&tree->list);
			list_add(&tree->list, &tree_list);
		}
		spin_unlock(&hash_lock);
		put_tree(tree);
	}

	while (barrier.prev != &tree_list) {
		struct audit_tree *tree;

		tree = container_of(barrier.prev, struct audit_tree, list);
		get_tree(tree);
		list_del(&tree->list);
		list_add(&tree->list, &barrier);
		mutex_unlock(&audit_filter_mutex);

		if (!failed) {
			struct node *node;
			spin_lock(&hash_lock);
			list_for_each_entry(node, &tree->chunks, list)
				node->index &= ~(1U<<31);
			spin_unlock(&hash_lock);
		} else {
			trim_marked(tree);
		}

		put_tree(tree);
		mutex_lock(&audit_filter_mutex);
	}
	list_del(&barrier);
	list_del(&cursor);
	mutex_unlock(&audit_filter_mutex);
910
	path_put(&path1);
Al Viro's avatar
Al Viro committed
911 912 913 914
	drop_collected_mounts(tagged);
	return failed;
}

915 916 917

static void audit_schedule_prune(void)
{
918
	wake_up_process(prune_thread);
919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945
}

/*
 * ... and that one is done if evict_chunk() decides to delay until the end
 * of syscall.  Runs synchronously.
 */
void audit_kill_trees(struct list_head *list)
{
	mutex_lock(&audit_cmd_mutex);
	mutex_lock(&audit_filter_mutex);

	while (!list_empty(list)) {
		struct audit_tree *victim;

		victim = list_entry(list->next, struct audit_tree, list);
		kill_rules(victim);
		list_del_init(&victim->list);

		mutex_unlock(&audit_filter_mutex);

		prune_one(victim);

		mutex_lock(&audit_filter_mutex);
	}

	mutex_unlock(&audit_filter_mutex);
	mutex_unlock(&audit_cmd_mutex);
Al Viro's avatar
Al Viro committed
946 947 948 949 950 951 952 953 954
}

/*
 *  Here comes the stuff asynchronous to auditctl operations
 */

static void evict_chunk(struct audit_chunk *chunk)
{
	struct audit_tree *owner;
955 956
	struct list_head *postponed = audit_killed_trees();
	int need_prune = 0;
Al Viro's avatar
Al Viro committed
957 958 959 960 961 962 963 964 965 966 967 968 969 970 971
	int n;

	if (chunk->dead)
		return;

	chunk->dead = 1;
	mutex_lock(&audit_filter_mutex);
	spin_lock(&hash_lock);
	while (!list_empty(&chunk->trees)) {
		owner = list_entry(chunk->trees.next,
				   struct audit_tree, same_root);
		owner->goner = 1;
		owner->root = NULL;
		list_del_init(&owner->same_root);
		spin_unlock(&hash_lock);
972 973 974 975 976 977 978
		if (!postponed) {
			kill_rules(owner);
			list_move(&owner->list, &prune_list);
			need_prune = 1;
		} else {
			list_move(&owner->list, postponed);
		}
Al Viro's avatar
Al Viro committed
979 980 981 982 983 984
		spin_lock(&hash_lock);
	}
	list_del_rcu(&chunk->hash);
	for (n = 0; n < chunk->count; n++)
		list_del_init(&chunk->owners[n].list);
	spin_unlock(&hash_lock);
985
	mutex_unlock(&audit_filter_mutex);
986 987
	if (need_prune)
		audit_schedule_prune();
Al Viro's avatar
Al Viro committed
988 989
}

990
static int audit_tree_handle_event(struct fsnotify_group *group,
991
				   struct inode *to_tell,
992
				   struct fsnotify_mark *inode_mark,
993
				   struct fsnotify_mark *vfsmount_mark,
994
				   u32 mask, const void *data, int data_type,
995 996
				   const unsigned char *file_name, u32 cookie,
				   struct fsnotify_iter_info *iter_info)
Al Viro's avatar
Al Viro committed
997
{
998
	return 0;
999
}
Al Viro's avatar
Al Viro committed
1000

1001
static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
1002 1003 1004 1005
{
	struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);

	evict_chunk(chunk);
1006 1007 1008 1009 1010 1011

	/*
	 * We are guaranteed to have at least one reference to the mark from
	 * either the inode or the caller of fsnotify_destroy_mark().
	 */
	BUG_ON(atomic_read(&entry->refcnt) < 1);
Al Viro's avatar
Al Viro committed
1012 1013
}

1014 1015 1016
static const struct fsnotify_ops audit_tree_ops = {
	.handle_event = audit_tree_handle_event,
	.freeing_mark = audit_tree_freeing_mark,
1017
	.free_mark = audit_tree_destroy_watch,
Al Viro's avatar
Al Viro committed
1018 1019 1020 1021 1022 1023
};

static int __init audit_tree_init(void)
{
	int i;

1024
	audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
1025 1026
	if (IS_ERR(audit_tree_group))
		audit_panic("cannot initialize fsnotify group for rectree watches");
Al Viro's avatar
Al Viro committed
1027 1028 1029 1030 1031 1032 1033

	for (i = 0; i < HASH_SIZE; i++)
		INIT_LIST_HEAD(&chunk_hash_heads[i]);

	return 0;
}
__initcall(audit_tree_init);