Root/kernel/audit_tree.c

1#include "audit.h"
2#include <linux/fsnotify_backend.h>
3#include <linux/namei.h>
4#include <linux/mount.h>
5#include <linux/kthread.h>
6#include <linux/slab.h>
7
8struct audit_tree;
9struct audit_chunk;
10
11struct audit_tree {
12    atomic_t count;
13    int goner;
14    struct audit_chunk *root;
15    struct list_head chunks;
16    struct list_head rules;
17    struct list_head list;
18    struct list_head same_root;
19    struct rcu_head head;
20    char pathname[];
21};
22
23struct audit_chunk {
24    struct list_head hash;
25    struct fsnotify_mark mark;
26    struct list_head trees; /* with root here */
27    int dead;
28    int count;
29    atomic_long_t refs;
30    struct rcu_head head;
31    struct node {
32        struct list_head list;
33        struct audit_tree *owner;
34        unsigned index; /* index; upper bit indicates 'will prune' */
35    } owners[];
36};
37
38static LIST_HEAD(tree_list);
39static LIST_HEAD(prune_list);
40
41/*
42 * One struct chunk is attached to each inode of interest.
43 * We replace struct chunk on tagging/untagging.
44 * Rules have pointer to struct audit_tree.
45 * Rules have struct list_head rlist forming a list of rules over
46 * the same tree.
47 * References to struct chunk are collected at audit_inode{,_child}()
48 * time and used in AUDIT_TREE rule matching.
49 * These references are dropped at the same time we are calling
50 * audit_free_names(), etc.
51 *
52 * Cyclic lists galore:
53 * tree.chunks anchors chunk.owners[].list hash_lock
54 * tree.rules anchors rule.rlist audit_filter_mutex
55 * chunk.trees anchors tree.same_root hash_lock
56 * chunk.hash is a hash with middle bits of watch.inode as
57 * a hash function. RCU, hash_lock
58 *
59 * tree is refcounted; one reference for "some rules on rules_list refer to
60 * it", one for each chunk with pointer to it.
61 *
62 * chunk is refcounted by embedded fsnotify_mark + .refs (non-zero refcount
63 * of watch contributes 1 to .refs).
64 *
65 * node.index allows to get from node.list to containing chunk.
66 * MSB of that sucker is stolen to mark taggings that we might have to
67 * revert - several operations have very unpleasant cleanup logics and
68 * that makes a difference. Some.
69 */
70
71static struct fsnotify_group *audit_tree_group;
72
73static struct audit_tree *alloc_tree(const char *s)
74{
75    struct audit_tree *tree;
76
77    tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
78    if (tree) {
79        atomic_set(&tree->count, 1);
80        tree->goner = 0;
81        INIT_LIST_HEAD(&tree->chunks);
82        INIT_LIST_HEAD(&tree->rules);
83        INIT_LIST_HEAD(&tree->list);
84        INIT_LIST_HEAD(&tree->same_root);
85        tree->root = NULL;
86        strcpy(tree->pathname, s);
87    }
88    return tree;
89}
90
91static inline void get_tree(struct audit_tree *tree)
92{
93    atomic_inc(&tree->count);
94}
95
96static inline void put_tree(struct audit_tree *tree)
97{
98    if (atomic_dec_and_test(&tree->count))
99        kfree_rcu(tree, head);
100}
101
102/* to avoid bringing the entire thing in audit.h */
103const char *audit_tree_path(struct audit_tree *tree)
104{
105    return tree->pathname;
106}
107
108static void free_chunk(struct audit_chunk *chunk)
109{
110    int i;
111
112    for (i = 0; i < chunk->count; i++) {
113        if (chunk->owners[i].owner)
114            put_tree(chunk->owners[i].owner);
115    }
116    kfree(chunk);
117}
118
119void audit_put_chunk(struct audit_chunk *chunk)
120{
121    if (atomic_long_dec_and_test(&chunk->refs))
122        free_chunk(chunk);
123}
124
125static void __put_chunk(struct rcu_head *rcu)
126{
127    struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
128    audit_put_chunk(chunk);
129}
130
131static void audit_tree_destroy_watch(struct fsnotify_mark *entry)
132{
133    struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
134    call_rcu(&chunk->head, __put_chunk);
135}
136
137static struct audit_chunk *alloc_chunk(int count)
138{
139    struct audit_chunk *chunk;
140    size_t size;
141    int i;
142
143    size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
144    chunk = kzalloc(size, GFP_KERNEL);
145    if (!chunk)
146        return NULL;
147
148    INIT_LIST_HEAD(&chunk->hash);
149    INIT_LIST_HEAD(&chunk->trees);
150    chunk->count = count;
151    atomic_long_set(&chunk->refs, 1);
152    for (i = 0; i < count; i++) {
153        INIT_LIST_HEAD(&chunk->owners[i].list);
154        chunk->owners[i].index = i;
155    }
156    fsnotify_init_mark(&chunk->mark, audit_tree_destroy_watch);
157    return chunk;
158}
159
160enum {HASH_SIZE = 128};
161static struct list_head chunk_hash_heads[HASH_SIZE];
162static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
163
164static inline struct list_head *chunk_hash(const struct inode *inode)
165{
166    unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
167    return chunk_hash_heads + n % HASH_SIZE;
168}
169
170/* hash_lock & entry->lock is held by caller */
171static void insert_hash(struct audit_chunk *chunk)
172{
173    struct fsnotify_mark *entry = &chunk->mark;
174    struct list_head *list;
175
176    if (!entry->i.inode)
177        return;
178    list = chunk_hash(entry->i.inode);
179    list_add_rcu(&chunk->hash, list);
180}
181
182/* called under rcu_read_lock */
183struct audit_chunk *audit_tree_lookup(const struct inode *inode)
184{
185    struct list_head *list = chunk_hash(inode);
186    struct audit_chunk *p;
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);
192            return p;
193        }
194    }
195    return NULL;
196}
197
198int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
199{
200    int n;
201    for (n = 0; n < chunk->count; n++)
202        if (chunk->owners[n].owner == tree)
203            return 1;
204    return 0;
205}
206
207/* tagging and untagging inodes with trees */
208
209static struct audit_chunk *find_chunk(struct node *p)
210{
211    int index = p->index & ~(1U<<31);
212    p -= index;
213    return container_of(p, struct audit_chunk, owners[0]);
214}
215
216static void untag_chunk(struct node *p)
217{
218    struct audit_chunk *chunk = find_chunk(p);
219    struct fsnotify_mark *entry = &chunk->mark;
220    struct audit_chunk *new = NULL;
221    struct audit_tree *owner;
222    int size = chunk->count - 1;
223    int i, j;
224
225    fsnotify_get_mark(entry);
226
227    spin_unlock(&hash_lock);
228
229    if (size)
230        new = alloc_chunk(size);
231
232    spin_lock(&entry->lock);
233    if (chunk->dead || !entry->i.inode) {
234        spin_unlock(&entry->lock);
235        if (new)
236            free_chunk(new);
237        goto out;
238    }
239
240    owner = p->owner;
241
242    if (!size) {
243        chunk->dead = 1;
244        spin_lock(&hash_lock);
245        list_del_init(&chunk->trees);
246        if (owner->root == chunk)
247            owner->root = NULL;
248        list_del_init(&p->list);
249        list_del_rcu(&chunk->hash);
250        spin_unlock(&hash_lock);
251        spin_unlock(&entry->lock);
252        fsnotify_destroy_mark(entry, audit_tree_group);
253        goto out;
254    }
255
256    if (!new)
257        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);
262        goto Fallback;
263    }
264
265    chunk->dead = 1;
266    spin_lock(&hash_lock);
267    list_replace_init(&chunk->trees, &new->trees);
268    if (owner->root == chunk) {
269        list_del_init(&owner->same_root);
270        owner->root = NULL;
271    }
272
273    for (i = j = 0; j <= size; i++, j++) {
274        struct audit_tree *s;
275        if (&chunk->owners[j] == p) {
276            list_del_init(&p->list);
277            i--;
278            continue;
279        }
280        s = chunk->owners[j].owner;
281        new->owners[i].owner = s;
282        new->owners[i].index = chunk->owners[j].index - j + i;
283        if (!s) /* result of earlier fallback */
284            continue;
285        get_tree(s);
286        list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
287    }
288
289    list_replace_rcu(&chunk->hash, &new->hash);
290    list_for_each_entry(owner, &new->trees, same_root)
291        owner->root = new;
292    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;
297
298Fallback:
299    // do the best we can
300    spin_lock(&hash_lock);
301    if (owner->root == chunk) {
302        list_del_init(&owner->same_root);
303        owner->root = NULL;
304    }
305    list_del_init(&p->list);
306    p->owner = NULL;
307    put_tree(owner);
308    spin_unlock(&hash_lock);
309    spin_unlock(&entry->lock);
310out:
311    fsnotify_put_mark(entry);
312    spin_lock(&hash_lock);
313}
314
315static int create_chunk(struct inode *inode, struct audit_tree *tree)
316{
317    struct fsnotify_mark *entry;
318    struct audit_chunk *chunk = alloc_chunk(1);
319    if (!chunk)
320        return -ENOMEM;
321
322    entry = &chunk->mark;
323    if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) {
324        fsnotify_put_mark(entry);
325        return -ENOSPC;
326    }
327
328    spin_lock(&entry->lock);
329    spin_lock(&hash_lock);
330    if (tree->goner) {
331        spin_unlock(&hash_lock);
332        chunk->dead = 1;
333        spin_unlock(&entry->lock);
334        fsnotify_destroy_mark(entry, audit_tree_group);
335        fsnotify_put_mark(entry);
336        return 0;
337    }
338    chunk->owners[0].index = (1U << 31);
339    chunk->owners[0].owner = tree;
340    get_tree(tree);
341    list_add(&chunk->owners[0].list, &tree->chunks);
342    if (!tree->root) {
343        tree->root = chunk;
344        list_add(&tree->same_root, &chunk->trees);
345    }
346    insert_hash(chunk);
347    spin_unlock(&hash_lock);
348    spin_unlock(&entry->lock);
349    fsnotify_put_mark(entry); /* drop initial reference */
350    return 0;
351}
352
353/* the first tagged inode becomes root of tree */
354static int tag_chunk(struct inode *inode, struct audit_tree *tree)
355{
356    struct fsnotify_mark *old_entry, *chunk_entry;
357    struct audit_tree *owner;
358    struct audit_chunk *chunk, *old;
359    struct node *p;
360    int n;
361
362    old_entry = fsnotify_find_inode_mark(audit_tree_group, inode);
363    if (!old_entry)
364        return create_chunk(inode, tree);
365
366    old = container_of(old_entry, struct audit_chunk, mark);
367
368    /* are we already there? */
369    spin_lock(&hash_lock);
370    for (n = 0; n < old->count; n++) {
371        if (old->owners[n].owner == tree) {
372            spin_unlock(&hash_lock);
373            fsnotify_put_mark(old_entry);
374            return 0;
375        }
376    }
377    spin_unlock(&hash_lock);
378
379    chunk = alloc_chunk(old->count + 1);
380    if (!chunk) {
381        fsnotify_put_mark(old_entry);
382        return -ENOMEM;
383    }
384
385    chunk_entry = &chunk->mark;
386
387    spin_lock(&old_entry->lock);
388    if (!old_entry->i.inode) {
389        /* old_entry is being shot, lets just lie */
390        spin_unlock(&old_entry->lock);
391        fsnotify_put_mark(old_entry);
392        free_chunk(chunk);
393        return -ENOENT;
394    }
395
396    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);
401        return -ENOSPC;
402    }
403
404    /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
405    spin_lock(&chunk_entry->lock);
406    spin_lock(&hash_lock);
407
408    /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
409    if (tree->goner) {
410        spin_unlock(&hash_lock);
411        chunk->dead = 1;
412        spin_unlock(&chunk_entry->lock);
413        spin_unlock(&old_entry->lock);
414
415        fsnotify_destroy_mark(chunk_entry, audit_tree_group);
416
417        fsnotify_put_mark(chunk_entry);
418        fsnotify_put_mark(old_entry);
419        return 0;
420    }
421    list_replace_init(&old->trees, &chunk->trees);
422    for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
423        struct audit_tree *s = old->owners[n].owner;
424        p->owner = s;
425        p->index = old->owners[n].index;
426        if (!s) /* result of fallback in untag */
427            continue;
428        get_tree(s);
429        list_replace_init(&old->owners[n].list, &p->list);
430    }
431    p->index = (chunk->count - 1) | (1U<<31);
432    p->owner = tree;
433    get_tree(tree);
434    list_add(&p->list, &tree->chunks);
435    list_replace_rcu(&old->hash, &chunk->hash);
436    list_for_each_entry(owner, &chunk->trees, same_root)
437        owner->root = chunk;
438    old->dead = 1;
439    if (!tree->root) {
440        tree->root = chunk;
441        list_add(&tree->same_root, &chunk->trees);
442    }
443    spin_unlock(&hash_lock);
444    spin_unlock(&chunk_entry->lock);
445    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 */
449    return 0;
450}
451
452static void audit_log_remove_rule(struct audit_krule *rule)
453{
454    struct audit_buffer *ab;
455
456    ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
457    if (unlikely(!ab))
458        return;
459    audit_log_format(ab, "op=");
460    audit_log_string(ab, "remove rule");
461    audit_log_format(ab, " dir=");
462    audit_log_untrustedstring(ab, rule->tree->pathname);
463    audit_log_key(ab, rule->filterkey);
464    audit_log_format(ab, " list=%d res=1", rule->listnr);
465    audit_log_end(ab);
466}
467
468static void kill_rules(struct audit_tree *tree)
469{
470    struct audit_krule *rule, *next;
471    struct audit_entry *entry;
472
473    list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
474        entry = container_of(rule, struct audit_entry, rule);
475
476        list_del_init(&rule->rlist);
477        if (rule->tree) {
478            /* not a half-baked one */
479            audit_log_remove_rule(rule);
480            rule->tree = NULL;
481            list_del_rcu(&entry->list);
482            list_del(&entry->rule.list);
483            call_rcu(&entry->rcu, audit_free_rule_rcu);
484        }
485    }
486}
487
488/*
489 * finish killing struct audit_tree
490 */
491static void prune_one(struct audit_tree *victim)
492{
493    spin_lock(&hash_lock);
494    while (!list_empty(&victim->chunks)) {
495        struct node *p;
496
497        p = list_entry(victim->chunks.next, struct node, list);
498
499        untag_chunk(p);
500    }
501    spin_unlock(&hash_lock);
502    put_tree(victim);
503}
504
505/* trim the uncommitted chunks from tree */
506
507static void trim_marked(struct audit_tree *tree)
508{
509    struct list_head *p, *q;
510    spin_lock(&hash_lock);
511    if (tree->goner) {
512        spin_unlock(&hash_lock);
513        return;
514    }
515    /* reorder */
516    for (p = tree->chunks.next; p != &tree->chunks; p = q) {
517        struct node *node = list_entry(p, struct node, list);
518        q = p->next;
519        if (node->index & (1U<<31)) {
520            list_del_init(p);
521            list_add(p, &tree->chunks);
522        }
523    }
524
525    while (!list_empty(&tree->chunks)) {
526        struct node *node;
527
528        node = list_entry(tree->chunks.next, struct node, list);
529
530        /* have we run out of marked? */
531        if (!(node->index & (1U<<31)))
532            break;
533
534        untag_chunk(node);
535    }
536    if (!tree->root && !tree->goner) {
537        tree->goner = 1;
538        spin_unlock(&hash_lock);
539        mutex_lock(&audit_filter_mutex);
540        kill_rules(tree);
541        list_del_init(&tree->list);
542        mutex_unlock(&audit_filter_mutex);
543        prune_one(tree);
544    } else {
545        spin_unlock(&hash_lock);
546    }
547}
548
549static void audit_schedule_prune(void);
550
551/* called with audit_filter_mutex */
552int audit_remove_tree_rule(struct audit_krule *rule)
553{
554    struct audit_tree *tree;
555    tree = rule->tree;
556    if (tree) {
557        spin_lock(&hash_lock);
558        list_del_init(&rule->rlist);
559        if (list_empty(&tree->rules) && !tree->goner) {
560            tree->root = NULL;
561            list_del_init(&tree->same_root);
562            tree->goner = 1;
563            list_move(&tree->list, &prune_list);
564            rule->tree = NULL;
565            spin_unlock(&hash_lock);
566            audit_schedule_prune();
567            return 1;
568        }
569        rule->tree = NULL;
570        spin_unlock(&hash_lock);
571        return 1;
572    }
573    return 0;
574}
575
576static int compare_root(struct vfsmount *mnt, void *arg)
577{
578    return mnt->mnt_root->d_inode == arg;
579}
580
581void audit_trim_trees(void)
582{
583    struct list_head cursor;
584
585    mutex_lock(&audit_filter_mutex);
586    list_add(&cursor, &tree_list);
587    while (cursor.next != &tree_list) {
588        struct audit_tree *tree;
589        struct path path;
590        struct vfsmount *root_mnt;
591        struct node *node;
592        int err;
593
594        tree = container_of(cursor.next, struct audit_tree, list);
595        get_tree(tree);
596        list_del(&cursor);
597        list_add(&cursor, &tree->list);
598        mutex_unlock(&audit_filter_mutex);
599
600        err = kern_path(tree->pathname, 0, &path);
601        if (err)
602            goto skip_it;
603
604        root_mnt = collect_mounts(&path);
605        path_put(&path);
606        if (IS_ERR(root_mnt))
607            goto skip_it;
608
609        spin_lock(&hash_lock);
610        list_for_each_entry(node, &tree->chunks, list) {
611            struct audit_chunk *chunk = find_chunk(node);
612            /* this could be NULL if the watch is dying else where... */
613            struct inode *inode = chunk->mark.i.inode;
614            node->index |= 1U<<31;
615            if (iterate_mounts(compare_root, inode, root_mnt))
616                node->index &= ~(1U<<31);
617        }
618        spin_unlock(&hash_lock);
619        trim_marked(tree);
620        drop_collected_mounts(root_mnt);
621skip_it:
622        put_tree(tree);
623        mutex_lock(&audit_filter_mutex);
624    }
625    list_del(&cursor);
626    mutex_unlock(&audit_filter_mutex);
627}
628
629int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
630{
631
632    if (pathname[0] != '/' ||
633        rule->listnr != AUDIT_FILTER_EXIT ||
634        op != Audit_equal ||
635        rule->inode_f || rule->watch || rule->tree)
636        return -EINVAL;
637    rule->tree = alloc_tree(pathname);
638    if (!rule->tree)
639        return -ENOMEM;
640    return 0;
641}
642
643void audit_put_tree(struct audit_tree *tree)
644{
645    put_tree(tree);
646}
647
648static int tag_mount(struct vfsmount *mnt, void *arg)
649{
650    return tag_chunk(mnt->mnt_root->d_inode, arg);
651}
652
653/* called with audit_filter_mutex */
654int audit_add_tree_rule(struct audit_krule *rule)
655{
656    struct audit_tree *seed = rule->tree, *tree;
657    struct path path;
658    struct vfsmount *mnt;
659    int err;
660
661    rule->tree = NULL;
662    list_for_each_entry(tree, &tree_list, list) {
663        if (!strcmp(seed->pathname, tree->pathname)) {
664            put_tree(seed);
665            rule->tree = tree;
666            list_add(&rule->rlist, &tree->rules);
667            return 0;
668        }
669    }
670    tree = seed;
671    list_add(&tree->list, &tree_list);
672    list_add(&rule->rlist, &tree->rules);
673    /* do not set rule->tree yet */
674    mutex_unlock(&audit_filter_mutex);
675
676    err = kern_path(tree->pathname, 0, &path);
677    if (err)
678        goto Err;
679    mnt = collect_mounts(&path);
680    path_put(&path);
681    if (IS_ERR(mnt)) {
682        err = PTR_ERR(mnt);
683        goto Err;
684    }
685
686    get_tree(tree);
687    err = iterate_mounts(tag_mount, tree, mnt);
688    drop_collected_mounts(mnt);
689
690    if (!err) {
691        struct node *node;
692        spin_lock(&hash_lock);
693        list_for_each_entry(node, &tree->chunks, list)
694            node->index &= ~(1U<<31);
695        spin_unlock(&hash_lock);
696    } else {
697        trim_marked(tree);
698        goto Err;
699    }
700
701    mutex_lock(&audit_filter_mutex);
702    if (list_empty(&rule->rlist)) {
703        put_tree(tree);
704        return -ENOENT;
705    }
706    rule->tree = tree;
707    put_tree(tree);
708
709    return 0;
710Err:
711    mutex_lock(&audit_filter_mutex);
712    list_del_init(&tree->list);
713    list_del_init(&tree->rules);
714    put_tree(tree);
715    return err;
716}
717
718int audit_tag_tree(char *old, char *new)
719{
720    struct list_head cursor, barrier;
721    int failed = 0;
722    struct path path1, path2;
723    struct vfsmount *tagged;
724    int err;
725
726    err = kern_path(new, 0, &path2);
727    if (err)
728        return err;
729    tagged = collect_mounts(&path2);
730    path_put(&path2);
731    if (IS_ERR(tagged))
732        return PTR_ERR(tagged);
733
734    err = kern_path(old, 0, &path1);
735    if (err) {
736        drop_collected_mounts(tagged);
737        return err;
738    }
739
740    mutex_lock(&audit_filter_mutex);
741    list_add(&barrier, &tree_list);
742    list_add(&cursor, &barrier);
743
744    while (cursor.next != &tree_list) {
745        struct audit_tree *tree;
746        int good_one = 0;
747
748        tree = container_of(cursor.next, struct audit_tree, list);
749        get_tree(tree);
750        list_del(&cursor);
751        list_add(&cursor, &tree->list);
752        mutex_unlock(&audit_filter_mutex);
753
754        err = kern_path(tree->pathname, 0, &path2);
755        if (!err) {
756            good_one = path_is_under(&path1, &path2);
757            path_put(&path2);
758        }
759
760        if (!good_one) {
761            put_tree(tree);
762            mutex_lock(&audit_filter_mutex);
763            continue;
764        }
765
766        failed = iterate_mounts(tag_mount, tree, tagged);
767        if (failed) {
768            put_tree(tree);
769            mutex_lock(&audit_filter_mutex);
770            break;
771        }
772
773        mutex_lock(&audit_filter_mutex);
774        spin_lock(&hash_lock);
775        if (!tree->goner) {
776            list_del(&tree->list);
777            list_add(&tree->list, &tree_list);
778        }
779        spin_unlock(&hash_lock);
780        put_tree(tree);
781    }
782
783    while (barrier.prev != &tree_list) {
784        struct audit_tree *tree;
785
786        tree = container_of(barrier.prev, struct audit_tree, list);
787        get_tree(tree);
788        list_del(&tree->list);
789        list_add(&tree->list, &barrier);
790        mutex_unlock(&audit_filter_mutex);
791
792        if (!failed) {
793            struct node *node;
794            spin_lock(&hash_lock);
795            list_for_each_entry(node, &tree->chunks, list)
796                node->index &= ~(1U<<31);
797            spin_unlock(&hash_lock);
798        } else {
799            trim_marked(tree);
800        }
801
802        put_tree(tree);
803        mutex_lock(&audit_filter_mutex);
804    }
805    list_del(&barrier);
806    list_del(&cursor);
807    mutex_unlock(&audit_filter_mutex);
808    path_put(&path1);
809    drop_collected_mounts(tagged);
810    return failed;
811}
812
813/*
814 * That gets run when evict_chunk() ends up needing to kill audit_tree.
815 * Runs from a separate thread.
816 */
817static int prune_tree_thread(void *unused)
818{
819    mutex_lock(&audit_cmd_mutex);
820    mutex_lock(&audit_filter_mutex);
821
822    while (!list_empty(&prune_list)) {
823        struct audit_tree *victim;
824
825        victim = list_entry(prune_list.next, struct audit_tree, list);
826        list_del_init(&victim->list);
827
828        mutex_unlock(&audit_filter_mutex);
829
830        prune_one(victim);
831
832        mutex_lock(&audit_filter_mutex);
833    }
834
835    mutex_unlock(&audit_filter_mutex);
836    mutex_unlock(&audit_cmd_mutex);
837    return 0;
838}
839
840static void audit_schedule_prune(void)
841{
842    kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
843}
844
845/*
846 * ... and that one is done if evict_chunk() decides to delay until the end
847 * of syscall. Runs synchronously.
848 */
849void audit_kill_trees(struct list_head *list)
850{
851    mutex_lock(&audit_cmd_mutex);
852    mutex_lock(&audit_filter_mutex);
853
854    while (!list_empty(list)) {
855        struct audit_tree *victim;
856
857        victim = list_entry(list->next, struct audit_tree, list);
858        kill_rules(victim);
859        list_del_init(&victim->list);
860
861        mutex_unlock(&audit_filter_mutex);
862
863        prune_one(victim);
864
865        mutex_lock(&audit_filter_mutex);
866    }
867
868    mutex_unlock(&audit_filter_mutex);
869    mutex_unlock(&audit_cmd_mutex);
870}
871
872/*
873 * Here comes the stuff asynchronous to auditctl operations
874 */
875
876static void evict_chunk(struct audit_chunk *chunk)
877{
878    struct audit_tree *owner;
879    struct list_head *postponed = audit_killed_trees();
880    int need_prune = 0;
881    int n;
882
883    if (chunk->dead)
884        return;
885
886    chunk->dead = 1;
887    mutex_lock(&audit_filter_mutex);
888    spin_lock(&hash_lock);
889    while (!list_empty(&chunk->trees)) {
890        owner = list_entry(chunk->trees.next,
891                   struct audit_tree, same_root);
892        owner->goner = 1;
893        owner->root = NULL;
894        list_del_init(&owner->same_root);
895        spin_unlock(&hash_lock);
896        if (!postponed) {
897            kill_rules(owner);
898            list_move(&owner->list, &prune_list);
899            need_prune = 1;
900        } else {
901            list_move(&owner->list, postponed);
902        }
903        spin_lock(&hash_lock);
904    }
905    list_del_rcu(&chunk->hash);
906    for (n = 0; n < chunk->count; n++)
907        list_del_init(&chunk->owners[n].list);
908    spin_unlock(&hash_lock);
909    if (need_prune)
910        audit_schedule_prune();
911    mutex_unlock(&audit_filter_mutex);
912}
913
914static int audit_tree_handle_event(struct fsnotify_group *group,
915                   struct inode *to_tell,
916                   struct fsnotify_mark *inode_mark,
917                   struct fsnotify_mark *vfsmount_mark,
918                   u32 mask, void *data, int data_type,
919                   const unsigned char *file_name, u32 cookie)
920{
921    return 0;
922}
923
924static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
925{
926    struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
927
928    evict_chunk(chunk);
929
930    /*
931     * We are guaranteed to have at least one reference to the mark from
932     * either the inode or the caller of fsnotify_destroy_mark().
933     */
934    BUG_ON(atomic_read(&entry->refcnt) < 1);
935}
936
937static const struct fsnotify_ops audit_tree_ops = {
938    .handle_event = audit_tree_handle_event,
939    .freeing_mark = audit_tree_freeing_mark,
940};
941
942static int __init audit_tree_init(void)
943{
944    int i;
945
946    audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
947    if (IS_ERR(audit_tree_group))
948        audit_panic("cannot initialize fsnotify group for rectree watches");
949
950    for (i = 0; i < HASH_SIZE; i++)
951        INIT_LIST_HEAD(&chunk_hash_heads[i]);
952
953    return 0;
954}
955__initcall(audit_tree_init);
956

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