audit_tree.c 22 KB
Newer Older
Al Viro's avatar
Al Viro committed
1
#include "audit.h"
2
#include <linux/fsnotify_backend.h>
Al Viro's avatar
Al Viro committed
3 4
#include <linux/namei.h>
#include <linux/mount.h>
5
#include <linux/kthread.h>
6
#include <linux/slab.h>
Al Viro's avatar
Al Viro committed
7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

struct audit_tree;
struct audit_chunk;

struct audit_tree {
	atomic_t count;
	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;
25
	struct fsnotify_mark mark;
Al Viro's avatar
Al Viro committed
26 27 28
	struct list_head trees;		/* with root here */
	int dead;
	int count;
29
	atomic_long_t refs;
Al Viro's avatar
Al Viro committed
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61
	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);

/*
 * 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.
 *
62
 * chunk is refcounted by embedded fsnotify_mark + .refs (non-zero refcount
63
 * of watch contributes 1 to .refs).
Al Viro's avatar
Al Viro committed
64 65 66 67 68 69 70
 *
 * 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.
 */

71
static struct fsnotify_group *audit_tree_group;
Al Viro's avatar
Al Viro committed
72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98

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) {
		atomic_set(&tree->count, 1);
		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)
{
	atomic_inc(&tree->count);
}

static inline void put_tree(struct audit_tree *tree)
{
	if (atomic_dec_and_test(&tree->count))
99
		kfree_rcu(tree, head);
Al Viro's avatar
Al Viro committed
100 101 102 103 104 105 106 107
}

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

108
static void free_chunk(struct audit_chunk *chunk)
Al Viro's avatar
Al Viro committed
109 110 111 112 113 114 115 116 117 118
{
	int i;

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

119
void audit_put_chunk(struct audit_chunk *chunk)
Al Viro's avatar
Al Viro committed
120
{
121 122
	if (atomic_long_dec_and_test(&chunk->refs))
		free_chunk(chunk);
Al Viro's avatar
Al Viro committed
123 124
}

125
static void __put_chunk(struct rcu_head *rcu)
Al Viro's avatar
Al Viro committed
126
{
127 128
	struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
	audit_put_chunk(chunk);
Al Viro's avatar
Al Viro committed
129 130
}

131
static void audit_tree_destroy_watch(struct fsnotify_mark *entry)
132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159
{
	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;
	}
	fsnotify_init_mark(&chunk->mark, audit_tree_destroy_watch);
	return chunk;
}

Al Viro's avatar
Al Viro committed
160 161 162 163 164 165 166 167 168 169
enum {HASH_SIZE = 128};
static struct list_head chunk_hash_heads[HASH_SIZE];
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);

static inline struct list_head *chunk_hash(const struct inode *inode)
{
	unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
	return chunk_hash_heads + n % HASH_SIZE;
}

170
/* hash_lock & entry->lock is held by caller */
Al Viro's avatar
Al Viro committed
171 172
static void insert_hash(struct audit_chunk *chunk)
{
173
	struct fsnotify_mark *entry = &chunk->mark;
174 175
	struct list_head *list;

176
	if (!entry->i.inode)
177
		return;
178
	list = chunk_hash(entry->i.inode);
Al Viro's avatar
Al Viro committed
179 180 181 182 183 184 185
	list_add_rcu(&chunk->hash, list);
}

/* called under rcu_read_lock */
struct audit_chunk *audit_tree_lookup(const struct inode *inode)
{
	struct list_head *list = chunk_hash(inode);
186
	struct audit_chunk *p;
Al Viro's avatar
Al Viro committed
187

188
	list_for_each_entry_rcu(p, list, hash) {
189
		/* mark.inode may have gone NULL, but who cares? */
190
		if (p->mark.i.inode == inode) {
191
			atomic_long_inc(&p->refs);
Al Viro's avatar
Al Viro committed
192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208
			return p;
		}
	}
	return NULL;
}

int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
{
	int n;
	for (n = 0; n < chunk->count; n++)
		if (chunk->owners[n].owner == tree)
			return 1;
	return 0;
}

/* tagging and untagging inodes with trees */

209 210 211 212 213 214 215 216
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
217
{
218
	struct audit_chunk *chunk = find_chunk(p);
219
	struct fsnotify_mark *entry = &chunk->mark;
220
	struct audit_chunk *new = NULL;
Al Viro's avatar
Al Viro committed
221 222 223 224
	struct audit_tree *owner;
	int size = chunk->count - 1;
	int i, j;

225
	fsnotify_get_mark(entry);
226 227 228

	spin_unlock(&hash_lock);

229 230 231
	if (size)
		new = alloc_chunk(size);

232
	spin_lock(&entry->lock);
233
	if (chunk->dead || !entry->i.inode) {
234
		spin_unlock(&entry->lock);
235 236
		if (new)
			free_chunk(new);
237
		goto out;
Al Viro's avatar
Al Viro committed
238 239 240 241 242 243 244 245 246 247 248 249 250
	}

	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);
251
		spin_unlock(&entry->lock);
252
		fsnotify_destroy_mark(entry, audit_tree_group);
253
		goto out;
Al Viro's avatar
Al Viro committed
254 255 256 257
	}

	if (!new)
		goto Fallback;
258

259
	fsnotify_duplicate_mark(&new->mark, entry);
260
	if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.i.inode, NULL, 1)) {
261
		fsnotify_put_mark(&new->mark);
Al Viro's avatar
Al Viro committed
262 263 264 265 266 267 268 269 270 271 272
		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;
	}

273
	for (i = j = 0; j <= size; i++, j++) {
Al Viro's avatar
Al Viro committed
274 275 276 277 278 279 280 281 282 283 284 285
		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);
286
		list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
Al Viro's avatar
Al Viro committed
287 288 289 290 291 292
	}

	list_replace_rcu(&chunk->hash, &new->hash);
	list_for_each_entry(owner, &new->trees, same_root)
		owner->root = new;
	spin_unlock(&hash_lock);
293
	spin_unlock(&entry->lock);
294
	fsnotify_destroy_mark(entry, audit_tree_group);
295
	fsnotify_put_mark(&new->mark);	/* drop initial reference */
296
	goto out;
Al Viro's avatar
Al Viro committed
297 298 299 300 301 302 303 304 305 306 307 308

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);
309
	spin_unlock(&entry->lock);
310
out:
311
	fsnotify_put_mark(entry);
312
	spin_lock(&hash_lock);
Al Viro's avatar
Al Viro committed
313 314 315 316
}

static int create_chunk(struct inode *inode, struct audit_tree *tree)
{
317
	struct fsnotify_mark *entry;
Al Viro's avatar
Al Viro committed
318 319 320 321
	struct audit_chunk *chunk = alloc_chunk(1);
	if (!chunk)
		return -ENOMEM;

322
	entry = &chunk->mark;
323
	if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) {
324
		fsnotify_put_mark(entry);
Al Viro's avatar
Al Viro committed
325 326 327
		return -ENOSPC;
	}

328
	spin_lock(&entry->lock);
Al Viro's avatar
Al Viro committed
329 330 331 332
	spin_lock(&hash_lock);
	if (tree->goner) {
		spin_unlock(&hash_lock);
		chunk->dead = 1;
333
		spin_unlock(&entry->lock);
334
		fsnotify_destroy_mark(entry, audit_tree_group);
335
		fsnotify_put_mark(entry);
Al Viro's avatar
Al Viro committed
336 337 338 339 340 341 342 343 344 345 346 347
		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);
348
	spin_unlock(&entry->lock);
349
	fsnotify_put_mark(entry);	/* drop initial reference */
Al Viro's avatar
Al Viro committed
350 351 352 353 354 355
	return 0;
}

/* the first tagged inode becomes root of tree */
static int tag_chunk(struct inode *inode, struct audit_tree *tree)
{
356
	struct fsnotify_mark *old_entry, *chunk_entry;
Al Viro's avatar
Al Viro committed
357 358 359 360 361
	struct audit_tree *owner;
	struct audit_chunk *chunk, *old;
	struct node *p;
	int n;

362
	old_entry = fsnotify_find_inode_mark(audit_tree_group, inode);
363
	if (!old_entry)
Al Viro's avatar
Al Viro committed
364 365
		return create_chunk(inode, tree);

366
	old = container_of(old_entry, struct audit_chunk, mark);
Al Viro's avatar
Al Viro committed
367 368 369 370 371 372

	/* 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);
373
			fsnotify_put_mark(old_entry);
Al Viro's avatar
Al Viro committed
374 375 376 377 378 379
			return 0;
		}
	}
	spin_unlock(&hash_lock);

	chunk = alloc_chunk(old->count + 1);
380
	if (!chunk) {
381
		fsnotify_put_mark(old_entry);
Al Viro's avatar
Al Viro committed
382
		return -ENOMEM;
383
	}
Al Viro's avatar
Al Viro committed
384

385 386 387
	chunk_entry = &chunk->mark;

	spin_lock(&old_entry->lock);
388
	if (!old_entry->i.inode) {
389 390 391
		/* old_entry is being shot, lets just lie */
		spin_unlock(&old_entry->lock);
		fsnotify_put_mark(old_entry);
Al Viro's avatar
Al Viro committed
392
		free_chunk(chunk);
393 394 395 396
		return -ENOENT;
	}

	fsnotify_duplicate_mark(chunk_entry, old_entry);
397
	if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->i.inode, NULL, 1)) {
398
		spin_unlock(&old_entry->lock);
399
		fsnotify_put_mark(chunk_entry);
400
		fsnotify_put_mark(old_entry);
Al Viro's avatar
Al Viro committed
401 402
		return -ENOSPC;
	}
403 404 405

	/* 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
406
	spin_lock(&hash_lock);
407 408

	/* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
Al Viro's avatar
Al Viro committed
409 410 411
	if (tree->goner) {
		spin_unlock(&hash_lock);
		chunk->dead = 1;
412 413 414
		spin_unlock(&chunk_entry->lock);
		spin_unlock(&old_entry->lock);

415
		fsnotify_destroy_mark(chunk_entry, audit_tree_group);
416 417 418

		fsnotify_put_mark(chunk_entry);
		fsnotify_put_mark(old_entry);
Al Viro's avatar
Al Viro committed
419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443
		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);
444 445
	spin_unlock(&chunk_entry->lock);
	spin_unlock(&old_entry->lock);
446
	fsnotify_destroy_mark(old_entry, audit_tree_group);
447
	fsnotify_put_mark(chunk_entry);	/* drop initial reference */
448
	fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
Al Viro's avatar
Al Viro committed
449 450 451
	return 0;
}

452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467
static void audit_log_remove_rule(struct audit_krule *rule)
{
	struct audit_buffer *ab;

	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
	if (unlikely(!ab))
		return;
	audit_log_format(ab, "op=");
	audit_log_string(ab, "remove rule");
	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
468 469 470 471 472 473 474 475 476 477 478
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 */
479
			audit_log_remove_rule(rule);
Al Viro's avatar
Al Viro committed
480 481
			rule->tree = NULL;
			list_del_rcu(&entry->list);
Al Viro's avatar
Al Viro committed
482
			list_del(&entry->rule.list);
Al Viro's avatar
Al Viro committed
483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498
			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);

499
		untag_chunk(p);
Al Viro's avatar
Al Viro committed
500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533
	}
	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;

534
		untag_chunk(node);
Al Viro's avatar
Al Viro committed
535 536 537 538 539 540 541 542 543 544 545 546 547 548
	}
	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);
	}
}

549 550
static void audit_schedule_prune(void);

Al Viro's avatar
Al Viro committed
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
/* 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
576 577 578 579 580
static int compare_root(struct vfsmount *mnt, void *arg)
{
	return mnt->mnt_root->d_inode == arg;
}

Al Viro's avatar
Al Viro committed
581 582 583 584 585 586 587 588
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;
589
		struct path path;
Al Viro's avatar
Al Viro committed
590 591 592 593 594 595 596 597 598 599
		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);

600
		err = kern_path(tree->pathname, 0, &path);
Al Viro's avatar
Al Viro committed
601 602 603
		if (err)
			goto skip_it;

604
		root_mnt = collect_mounts(&path);
605
		path_put(&path);
606
		if (IS_ERR(root_mnt))
Al Viro's avatar
Al Viro committed
607 608 609 610
			goto skip_it;

		spin_lock(&hash_lock);
		list_for_each_entry(node, &tree->chunks, list) {
611
			struct audit_chunk *chunk = find_chunk(node);
Lucas De Marchi's avatar
Lucas De Marchi committed
612
			/* this could be NULL if the watch is dying else where... */
613
			struct inode *inode = chunk->mark.i.inode;
Al Viro's avatar
Al Viro committed
614
			node->index |= 1U<<31;
Al Viro's avatar
Al Viro committed
615 616
			if (iterate_mounts(compare_root, inode, root_mnt))
				node->index &= ~(1U<<31);
Al Viro's avatar
Al Viro committed
617 618 619 620 621
		}
		spin_unlock(&hash_lock);
		trim_marked(tree);
		drop_collected_mounts(root_mnt);
skip_it:
622
		put_tree(tree);
Al Viro's avatar
Al Viro committed
623 624 625 626 627 628 629 630 631 632 633
		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 ||
634
	    op != Audit_equal ||
Al Viro's avatar
Al Viro committed
635 636 637 638 639 640 641 642 643 644 645 646 647
	    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
648 649 650 651 652
static int tag_mount(struct vfsmount *mnt, void *arg)
{
	return tag_chunk(mnt->mnt_root->d_inode, arg);
}

Al Viro's avatar
Al Viro committed
653 654 655 656
/* called with audit_filter_mutex */
int audit_add_tree_rule(struct audit_krule *rule)
{
	struct audit_tree *seed = rule->tree, *tree;
657
	struct path path;
Al Viro's avatar
Al Viro committed
658
	struct vfsmount *mnt;
Al Viro's avatar
Al Viro committed
659 660
	int err;

661
	rule->tree = NULL;
Al Viro's avatar
Al Viro committed
662 663 664 665 666 667 668 669 670 671 672 673 674 675
	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);

676
	err = kern_path(tree->pathname, 0, &path);
Al Viro's avatar
Al Viro committed
677 678
	if (err)
		goto Err;
679
	mnt = collect_mounts(&path);
680
	path_put(&path);
681 682
	if (IS_ERR(mnt)) {
		err = PTR_ERR(mnt);
Al Viro's avatar
Al Viro committed
683 684 685 686
		goto Err;
	}

	get_tree(tree);
Al Viro's avatar
Al Viro committed
687
	err = iterate_mounts(tag_mount, tree, mnt);
Al Viro's avatar
Al Viro committed
688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721
	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;
722
	struct path path1, path2;
Al Viro's avatar
Al Viro committed
723 724 725
	struct vfsmount *tagged;
	int err;

726
	err = kern_path(new, 0, &path2);
Al Viro's avatar
Al Viro committed
727 728
	if (err)
		return err;
729 730
	tagged = collect_mounts(&path2);
	path_put(&path2);
731 732
	if (IS_ERR(tagged))
		return PTR_ERR(tagged);
Al Viro's avatar
Al Viro committed
733

734
	err = kern_path(old, 0, &path1);
Al Viro's avatar
Al Viro committed
735 736 737 738 739 740 741 742 743 744 745
	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;
746
		int good_one = 0;
Al Viro's avatar
Al Viro committed
747 748 749 750 751 752 753

		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);

754 755 756 757
		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
758 759
		}

760
		if (!good_one) {
Al Viro's avatar
Al Viro committed
761 762 763 764 765
			put_tree(tree);
			mutex_lock(&audit_filter_mutex);
			continue;
		}

Al Viro's avatar
Al Viro committed
766
		failed = iterate_mounts(tag_mount, tree, tagged);
Al Viro's avatar
Al Viro committed
767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807
		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);
808
	path_put(&path1);
Al Viro's avatar
Al Viro committed
809 810 811 812 813 814
	drop_collected_mounts(tagged);
	return failed;
}

/*
 * That gets run when evict_chunk() ends up needing to kill audit_tree.
815
 * Runs from a separate thread.
Al Viro's avatar
Al Viro committed
816
 */
817
static int prune_tree_thread(void *unused)
Al Viro's avatar
Al Viro committed
818
{
819
	mutex_lock(&audit_cmd_mutex);
Al Viro's avatar
Al Viro committed
820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835
	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);
836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869
	mutex_unlock(&audit_cmd_mutex);
	return 0;
}

static void audit_schedule_prune(void)
{
	kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
}

/*
 * ... 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
870 871 872 873 874 875 876 877 878
}

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

static void evict_chunk(struct audit_chunk *chunk)
{
	struct audit_tree *owner;
879 880
	struct list_head *postponed = audit_killed_trees();
	int need_prune = 0;
Al Viro's avatar
Al Viro committed
881 882 883 884 885 886 887 888 889 890 891 892 893 894 895
	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);
896 897 898 899 900 901 902
		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
903 904 905 906 907 908
		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);
909 910
	if (need_prune)
		audit_schedule_prune();
Al Viro's avatar
Al Viro committed
911 912 913
	mutex_unlock(&audit_filter_mutex);
}

914
static int audit_tree_handle_event(struct fsnotify_group *group,
915
				   struct inode *to_tell,
916
				   struct fsnotify_mark *inode_mark,
917 918 919
				   struct fsnotify_mark *vfsmount_mark,
				   u32 mask, void *data, int data_type,
				   const unsigned char *file_name)
Al Viro's avatar
Al Viro committed
920
{
921
	return 0;
922
}
Al Viro's avatar
Al Viro committed
923

924
static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
925 926 927 928
{
	struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);

	evict_chunk(chunk);
929 930 931 932 933 934

	/*
	 * 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
935 936
}

937 938 939
static const struct fsnotify_ops audit_tree_ops = {
	.handle_event = audit_tree_handle_event,
	.freeing_mark = audit_tree_freeing_mark,
Al Viro's avatar
Al Viro committed
940 941 942 943 944 945
};

static int __init audit_tree_init(void)
{
	int i;

946
	audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
947 948
	if (IS_ERR(audit_tree_group))
		audit_panic("cannot initialize fsnotify group for rectree watches");
Al Viro's avatar
Al Viro committed
949 950 951 952 953 954 955

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

	return 0;
}
__initcall(audit_tree_init);