Root/kernel/audit_tree.c

1#include "audit.h"
2#include <linux/inotify.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 inotify_watch watch;
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 inotify_watch + .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 inotify_handle *rtree_ih;
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 void __put_tree(struct rcu_head *rcu)
97{
98    struct audit_tree *tree = container_of(rcu, struct audit_tree, head);
99    kfree(tree);
100}
101
102static inline void put_tree(struct audit_tree *tree)
103{
104    if (atomic_dec_and_test(&tree->count))
105        call_rcu(&tree->head, __put_tree);
106}
107
108/* to avoid bringing the entire thing in audit.h */
109const char *audit_tree_path(struct audit_tree *tree)
110{
111    return tree->pathname;
112}
113
114static struct audit_chunk *alloc_chunk(int count)
115{
116    struct audit_chunk *chunk;
117    size_t size;
118    int i;
119
120    size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
121    chunk = kzalloc(size, GFP_KERNEL);
122    if (!chunk)
123        return NULL;
124
125    INIT_LIST_HEAD(&chunk->hash);
126    INIT_LIST_HEAD(&chunk->trees);
127    chunk->count = count;
128    atomic_long_set(&chunk->refs, 1);
129    for (i = 0; i < count; i++) {
130        INIT_LIST_HEAD(&chunk->owners[i].list);
131        chunk->owners[i].index = i;
132    }
133    inotify_init_watch(&chunk->watch);
134    return chunk;
135}
136
137static void free_chunk(struct audit_chunk *chunk)
138{
139    int i;
140
141    for (i = 0; i < chunk->count; i++) {
142        if (chunk->owners[i].owner)
143            put_tree(chunk->owners[i].owner);
144    }
145    kfree(chunk);
146}
147
148void audit_put_chunk(struct audit_chunk *chunk)
149{
150    if (atomic_long_dec_and_test(&chunk->refs))
151        free_chunk(chunk);
152}
153
154static void __put_chunk(struct rcu_head *rcu)
155{
156    struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
157    audit_put_chunk(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 is held by caller */
171static void insert_hash(struct audit_chunk *chunk)
172{
173    struct list_head *list = chunk_hash(chunk->watch.inode);
174    list_add_rcu(&chunk->hash, list);
175}
176
177/* called under rcu_read_lock */
178struct audit_chunk *audit_tree_lookup(const struct inode *inode)
179{
180    struct list_head *list = chunk_hash(inode);
181    struct audit_chunk *p;
182
183    list_for_each_entry_rcu(p, list, hash) {
184        if (p->watch.inode == inode) {
185            atomic_long_inc(&p->refs);
186            return p;
187        }
188    }
189    return NULL;
190}
191
192int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
193{
194    int n;
195    for (n = 0; n < chunk->count; n++)
196        if (chunk->owners[n].owner == tree)
197            return 1;
198    return 0;
199}
200
201/* tagging and untagging inodes with trees */
202
203static struct audit_chunk *find_chunk(struct node *p)
204{
205    int index = p->index & ~(1U<<31);
206    p -= index;
207    return container_of(p, struct audit_chunk, owners[0]);
208}
209
210static void untag_chunk(struct node *p)
211{
212    struct audit_chunk *chunk = find_chunk(p);
213    struct audit_chunk *new;
214    struct audit_tree *owner;
215    int size = chunk->count - 1;
216    int i, j;
217
218    if (!pin_inotify_watch(&chunk->watch)) {
219        /*
220         * Filesystem is shutting down; all watches are getting
221         * evicted, just take it off the node list for this
222         * tree and let the eviction logics take care of the
223         * rest.
224         */
225        owner = p->owner;
226        if (owner->root == chunk) {
227            list_del_init(&owner->same_root);
228            owner->root = NULL;
229        }
230        list_del_init(&p->list);
231        p->owner = NULL;
232        put_tree(owner);
233        return;
234    }
235
236    spin_unlock(&hash_lock);
237
238    /*
239     * pin_inotify_watch() succeeded, so the watch won't go away
240     * from under us.
241     */
242    mutex_lock(&chunk->watch.inode->inotify_mutex);
243    if (chunk->dead) {
244        mutex_unlock(&chunk->watch.inode->inotify_mutex);
245        goto out;
246    }
247
248    owner = p->owner;
249
250    if (!size) {
251        chunk->dead = 1;
252        spin_lock(&hash_lock);
253        list_del_init(&chunk->trees);
254        if (owner->root == chunk)
255            owner->root = NULL;
256        list_del_init(&p->list);
257        list_del_rcu(&chunk->hash);
258        spin_unlock(&hash_lock);
259        inotify_evict_watch(&chunk->watch);
260        mutex_unlock(&chunk->watch.inode->inotify_mutex);
261        put_inotify_watch(&chunk->watch);
262        goto out;
263    }
264
265    new = alloc_chunk(size);
266    if (!new)
267        goto Fallback;
268    if (inotify_clone_watch(&chunk->watch, &new->watch) < 0) {
269        free_chunk(new);
270        goto Fallback;
271    }
272
273    chunk->dead = 1;
274    spin_lock(&hash_lock);
275    list_replace_init(&chunk->trees, &new->trees);
276    if (owner->root == chunk) {
277        list_del_init(&owner->same_root);
278        owner->root = NULL;
279    }
280
281    for (i = j = 0; j <= size; i++, j++) {
282        struct audit_tree *s;
283        if (&chunk->owners[j] == p) {
284            list_del_init(&p->list);
285            i--;
286            continue;
287        }
288        s = chunk->owners[j].owner;
289        new->owners[i].owner = s;
290        new->owners[i].index = chunk->owners[j].index - j + i;
291        if (!s) /* result of earlier fallback */
292            continue;
293        get_tree(s);
294        list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
295    }
296
297    list_replace_rcu(&chunk->hash, &new->hash);
298    list_for_each_entry(owner, &new->trees, same_root)
299        owner->root = new;
300    spin_unlock(&hash_lock);
301    inotify_evict_watch(&chunk->watch);
302    mutex_unlock(&chunk->watch.inode->inotify_mutex);
303    put_inotify_watch(&chunk->watch);
304    goto out;
305
306Fallback:
307    // do the best we can
308    spin_lock(&hash_lock);
309    if (owner->root == chunk) {
310        list_del_init(&owner->same_root);
311        owner->root = NULL;
312    }
313    list_del_init(&p->list);
314    p->owner = NULL;
315    put_tree(owner);
316    spin_unlock(&hash_lock);
317    mutex_unlock(&chunk->watch.inode->inotify_mutex);
318out:
319    unpin_inotify_watch(&chunk->watch);
320    spin_lock(&hash_lock);
321}
322
323static int create_chunk(struct inode *inode, struct audit_tree *tree)
324{
325    struct audit_chunk *chunk = alloc_chunk(1);
326    if (!chunk)
327        return -ENOMEM;
328
329    if (inotify_add_watch(rtree_ih, &chunk->watch, inode, IN_IGNORED | IN_DELETE_SELF) < 0) {
330        free_chunk(chunk);
331        return -ENOSPC;
332    }
333
334    mutex_lock(&inode->inotify_mutex);
335    spin_lock(&hash_lock);
336    if (tree->goner) {
337        spin_unlock(&hash_lock);
338        chunk->dead = 1;
339        inotify_evict_watch(&chunk->watch);
340        mutex_unlock(&inode->inotify_mutex);
341        put_inotify_watch(&chunk->watch);
342        return 0;
343    }
344    chunk->owners[0].index = (1U << 31);
345    chunk->owners[0].owner = tree;
346    get_tree(tree);
347    list_add(&chunk->owners[0].list, &tree->chunks);
348    if (!tree->root) {
349        tree->root = chunk;
350        list_add(&tree->same_root, &chunk->trees);
351    }
352    insert_hash(chunk);
353    spin_unlock(&hash_lock);
354    mutex_unlock(&inode->inotify_mutex);
355    return 0;
356}
357
358/* the first tagged inode becomes root of tree */
359static int tag_chunk(struct inode *inode, struct audit_tree *tree)
360{
361    struct inotify_watch *watch;
362    struct audit_tree *owner;
363    struct audit_chunk *chunk, *old;
364    struct node *p;
365    int n;
366
367    if (inotify_find_watch(rtree_ih, inode, &watch) < 0)
368        return create_chunk(inode, tree);
369
370    old = container_of(watch, struct audit_chunk, watch);
371
372    /* are we already there? */
373    spin_lock(&hash_lock);
374    for (n = 0; n < old->count; n++) {
375        if (old->owners[n].owner == tree) {
376            spin_unlock(&hash_lock);
377            put_inotify_watch(&old->watch);
378            return 0;
379        }
380    }
381    spin_unlock(&hash_lock);
382
383    chunk = alloc_chunk(old->count + 1);
384    if (!chunk) {
385        put_inotify_watch(&old->watch);
386        return -ENOMEM;
387    }
388
389    mutex_lock(&inode->inotify_mutex);
390    if (inotify_clone_watch(&old->watch, &chunk->watch) < 0) {
391        mutex_unlock(&inode->inotify_mutex);
392        put_inotify_watch(&old->watch);
393        free_chunk(chunk);
394        return -ENOSPC;
395    }
396    spin_lock(&hash_lock);
397    if (tree->goner) {
398        spin_unlock(&hash_lock);
399        chunk->dead = 1;
400        inotify_evict_watch(&chunk->watch);
401        mutex_unlock(&inode->inotify_mutex);
402        put_inotify_watch(&old->watch);
403        put_inotify_watch(&chunk->watch);
404        return 0;
405    }
406    list_replace_init(&old->trees, &chunk->trees);
407    for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
408        struct audit_tree *s = old->owners[n].owner;
409        p->owner = s;
410        p->index = old->owners[n].index;
411        if (!s) /* result of fallback in untag */
412            continue;
413        get_tree(s);
414        list_replace_init(&old->owners[n].list, &p->list);
415    }
416    p->index = (chunk->count - 1) | (1U<<31);
417    p->owner = tree;
418    get_tree(tree);
419    list_add(&p->list, &tree->chunks);
420    list_replace_rcu(&old->hash, &chunk->hash);
421    list_for_each_entry(owner, &chunk->trees, same_root)
422        owner->root = chunk;
423    old->dead = 1;
424    if (!tree->root) {
425        tree->root = chunk;
426        list_add(&tree->same_root, &chunk->trees);
427    }
428    spin_unlock(&hash_lock);
429    inotify_evict_watch(&old->watch);
430    mutex_unlock(&inode->inotify_mutex);
431    put_inotify_watch(&old->watch); /* pair to inotify_find_watch */
432    put_inotify_watch(&old->watch); /* and kill it */
433    return 0;
434}
435
436static void kill_rules(struct audit_tree *tree)
437{
438    struct audit_krule *rule, *next;
439    struct audit_entry *entry;
440    struct audit_buffer *ab;
441
442    list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
443        entry = container_of(rule, struct audit_entry, rule);
444
445        list_del_init(&rule->rlist);
446        if (rule->tree) {
447            /* not a half-baked one */
448            ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
449            audit_log_format(ab, "op=");
450            audit_log_string(ab, "remove rule");
451            audit_log_format(ab, " dir=");
452            audit_log_untrustedstring(ab, rule->tree->pathname);
453            audit_log_key(ab, rule->filterkey);
454            audit_log_format(ab, " list=%d res=1", rule->listnr);
455            audit_log_end(ab);
456            rule->tree = NULL;
457            list_del_rcu(&entry->list);
458            list_del(&entry->rule.list);
459            call_rcu(&entry->rcu, audit_free_rule_rcu);
460        }
461    }
462}
463
464/*
465 * finish killing struct audit_tree
466 */
467static void prune_one(struct audit_tree *victim)
468{
469    spin_lock(&hash_lock);
470    while (!list_empty(&victim->chunks)) {
471        struct node *p;
472
473        p = list_entry(victim->chunks.next, struct node, list);
474
475        untag_chunk(p);
476    }
477    spin_unlock(&hash_lock);
478    put_tree(victim);
479}
480
481/* trim the uncommitted chunks from tree */
482
483static void trim_marked(struct audit_tree *tree)
484{
485    struct list_head *p, *q;
486    spin_lock(&hash_lock);
487    if (tree->goner) {
488        spin_unlock(&hash_lock);
489        return;
490    }
491    /* reorder */
492    for (p = tree->chunks.next; p != &tree->chunks; p = q) {
493        struct node *node = list_entry(p, struct node, list);
494        q = p->next;
495        if (node->index & (1U<<31)) {
496            list_del_init(p);
497            list_add(p, &tree->chunks);
498        }
499    }
500
501    while (!list_empty(&tree->chunks)) {
502        struct node *node;
503
504        node = list_entry(tree->chunks.next, struct node, list);
505
506        /* have we run out of marked? */
507        if (!(node->index & (1U<<31)))
508            break;
509
510        untag_chunk(node);
511    }
512    if (!tree->root && !tree->goner) {
513        tree->goner = 1;
514        spin_unlock(&hash_lock);
515        mutex_lock(&audit_filter_mutex);
516        kill_rules(tree);
517        list_del_init(&tree->list);
518        mutex_unlock(&audit_filter_mutex);
519        prune_one(tree);
520    } else {
521        spin_unlock(&hash_lock);
522    }
523}
524
525static void audit_schedule_prune(void);
526
527/* called with audit_filter_mutex */
528int audit_remove_tree_rule(struct audit_krule *rule)
529{
530    struct audit_tree *tree;
531    tree = rule->tree;
532    if (tree) {
533        spin_lock(&hash_lock);
534        list_del_init(&rule->rlist);
535        if (list_empty(&tree->rules) && !tree->goner) {
536            tree->root = NULL;
537            list_del_init(&tree->same_root);
538            tree->goner = 1;
539            list_move(&tree->list, &prune_list);
540            rule->tree = NULL;
541            spin_unlock(&hash_lock);
542            audit_schedule_prune();
543            return 1;
544        }
545        rule->tree = NULL;
546        spin_unlock(&hash_lock);
547        return 1;
548    }
549    return 0;
550}
551
552static int compare_root(struct vfsmount *mnt, void *arg)
553{
554    return mnt->mnt_root->d_inode == arg;
555}
556
557void audit_trim_trees(void)
558{
559    struct list_head cursor;
560
561    mutex_lock(&audit_filter_mutex);
562    list_add(&cursor, &tree_list);
563    while (cursor.next != &tree_list) {
564        struct audit_tree *tree;
565        struct path path;
566        struct vfsmount *root_mnt;
567        struct node *node;
568        int err;
569
570        tree = container_of(cursor.next, struct audit_tree, list);
571        get_tree(tree);
572        list_del(&cursor);
573        list_add(&cursor, &tree->list);
574        mutex_unlock(&audit_filter_mutex);
575
576        err = kern_path(tree->pathname, 0, &path);
577        if (err)
578            goto skip_it;
579
580        root_mnt = collect_mounts(&path);
581        path_put(&path);
582        if (!root_mnt)
583            goto skip_it;
584
585        spin_lock(&hash_lock);
586        list_for_each_entry(node, &tree->chunks, list) {
587            struct inode *inode = find_chunk(node)->watch.inode;
588            node->index |= 1U<<31;
589            if (iterate_mounts(compare_root, inode, root_mnt))
590                node->index &= ~(1U<<31);
591        }
592        spin_unlock(&hash_lock);
593        trim_marked(tree);
594        put_tree(tree);
595        drop_collected_mounts(root_mnt);
596skip_it:
597        mutex_lock(&audit_filter_mutex);
598    }
599    list_del(&cursor);
600    mutex_unlock(&audit_filter_mutex);
601}
602
603int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
604{
605
606    if (pathname[0] != '/' ||
607        rule->listnr != AUDIT_FILTER_EXIT ||
608        op != Audit_equal ||
609        rule->inode_f || rule->watch || rule->tree)
610        return -EINVAL;
611    rule->tree = alloc_tree(pathname);
612    if (!rule->tree)
613        return -ENOMEM;
614    return 0;
615}
616
617void audit_put_tree(struct audit_tree *tree)
618{
619    put_tree(tree);
620}
621
622static int tag_mount(struct vfsmount *mnt, void *arg)
623{
624    return tag_chunk(mnt->mnt_root->d_inode, arg);
625}
626
627/* called with audit_filter_mutex */
628int audit_add_tree_rule(struct audit_krule *rule)
629{
630    struct audit_tree *seed = rule->tree, *tree;
631    struct path path;
632    struct vfsmount *mnt;
633    int err;
634
635    list_for_each_entry(tree, &tree_list, list) {
636        if (!strcmp(seed->pathname, tree->pathname)) {
637            put_tree(seed);
638            rule->tree = tree;
639            list_add(&rule->rlist, &tree->rules);
640            return 0;
641        }
642    }
643    tree = seed;
644    list_add(&tree->list, &tree_list);
645    list_add(&rule->rlist, &tree->rules);
646    /* do not set rule->tree yet */
647    mutex_unlock(&audit_filter_mutex);
648
649    err = kern_path(tree->pathname, 0, &path);
650    if (err)
651        goto Err;
652    mnt = collect_mounts(&path);
653    path_put(&path);
654    if (!mnt) {
655        err = -ENOMEM;
656        goto Err;
657    }
658
659    get_tree(tree);
660    err = iterate_mounts(tag_mount, tree, mnt);
661    drop_collected_mounts(mnt);
662
663    if (!err) {
664        struct node *node;
665        spin_lock(&hash_lock);
666        list_for_each_entry(node, &tree->chunks, list)
667            node->index &= ~(1U<<31);
668        spin_unlock(&hash_lock);
669    } else {
670        trim_marked(tree);
671        goto Err;
672    }
673
674    mutex_lock(&audit_filter_mutex);
675    if (list_empty(&rule->rlist)) {
676        put_tree(tree);
677        return -ENOENT;
678    }
679    rule->tree = tree;
680    put_tree(tree);
681
682    return 0;
683Err:
684    mutex_lock(&audit_filter_mutex);
685    list_del_init(&tree->list);
686    list_del_init(&tree->rules);
687    put_tree(tree);
688    return err;
689}
690
691int audit_tag_tree(char *old, char *new)
692{
693    struct list_head cursor, barrier;
694    int failed = 0;
695    struct path path1, path2;
696    struct vfsmount *tagged;
697    int err;
698
699    err = kern_path(new, 0, &path2);
700    if (err)
701        return err;
702    tagged = collect_mounts(&path2);
703    path_put(&path2);
704    if (!tagged)
705        return -ENOMEM;
706
707    err = kern_path(old, 0, &path1);
708    if (err) {
709        drop_collected_mounts(tagged);
710        return err;
711    }
712
713    mutex_lock(&audit_filter_mutex);
714    list_add(&barrier, &tree_list);
715    list_add(&cursor, &barrier);
716
717    while (cursor.next != &tree_list) {
718        struct audit_tree *tree;
719        int good_one = 0;
720
721        tree = container_of(cursor.next, struct audit_tree, list);
722        get_tree(tree);
723        list_del(&cursor);
724        list_add(&cursor, &tree->list);
725        mutex_unlock(&audit_filter_mutex);
726
727        err = kern_path(tree->pathname, 0, &path2);
728        if (!err) {
729            good_one = path_is_under(&path1, &path2);
730            path_put(&path2);
731        }
732
733        if (!good_one) {
734            put_tree(tree);
735            mutex_lock(&audit_filter_mutex);
736            continue;
737        }
738
739        failed = iterate_mounts(tag_mount, tree, tagged);
740        if (failed) {
741            put_tree(tree);
742            mutex_lock(&audit_filter_mutex);
743            break;
744        }
745
746        mutex_lock(&audit_filter_mutex);
747        spin_lock(&hash_lock);
748        if (!tree->goner) {
749            list_del(&tree->list);
750            list_add(&tree->list, &tree_list);
751        }
752        spin_unlock(&hash_lock);
753        put_tree(tree);
754    }
755
756    while (barrier.prev != &tree_list) {
757        struct audit_tree *tree;
758
759        tree = container_of(barrier.prev, struct audit_tree, list);
760        get_tree(tree);
761        list_del(&tree->list);
762        list_add(&tree->list, &barrier);
763        mutex_unlock(&audit_filter_mutex);
764
765        if (!failed) {
766            struct node *node;
767            spin_lock(&hash_lock);
768            list_for_each_entry(node, &tree->chunks, list)
769                node->index &= ~(1U<<31);
770            spin_unlock(&hash_lock);
771        } else {
772            trim_marked(tree);
773        }
774
775        put_tree(tree);
776        mutex_lock(&audit_filter_mutex);
777    }
778    list_del(&barrier);
779    list_del(&cursor);
780    mutex_unlock(&audit_filter_mutex);
781    path_put(&path1);
782    drop_collected_mounts(tagged);
783    return failed;
784}
785
786/*
787 * That gets run when evict_chunk() ends up needing to kill audit_tree.
788 * Runs from a separate thread.
789 */
790static int prune_tree_thread(void *unused)
791{
792    mutex_lock(&audit_cmd_mutex);
793    mutex_lock(&audit_filter_mutex);
794
795    while (!list_empty(&prune_list)) {
796        struct audit_tree *victim;
797
798        victim = list_entry(prune_list.next, struct audit_tree, list);
799        list_del_init(&victim->list);
800
801        mutex_unlock(&audit_filter_mutex);
802
803        prune_one(victim);
804
805        mutex_lock(&audit_filter_mutex);
806    }
807
808    mutex_unlock(&audit_filter_mutex);
809    mutex_unlock(&audit_cmd_mutex);
810    return 0;
811}
812
813static void audit_schedule_prune(void)
814{
815    kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
816}
817
818/*
819 * ... and that one is done if evict_chunk() decides to delay until the end
820 * of syscall. Runs synchronously.
821 */
822void audit_kill_trees(struct list_head *list)
823{
824    mutex_lock(&audit_cmd_mutex);
825    mutex_lock(&audit_filter_mutex);
826
827    while (!list_empty(list)) {
828        struct audit_tree *victim;
829
830        victim = list_entry(list->next, struct audit_tree, list);
831        kill_rules(victim);
832        list_del_init(&victim->list);
833
834        mutex_unlock(&audit_filter_mutex);
835
836        prune_one(victim);
837
838        mutex_lock(&audit_filter_mutex);
839    }
840
841    mutex_unlock(&audit_filter_mutex);
842    mutex_unlock(&audit_cmd_mutex);
843}
844
845/*
846 * Here comes the stuff asynchronous to auditctl operations
847 */
848
849/* inode->inotify_mutex is locked */
850static void evict_chunk(struct audit_chunk *chunk)
851{
852    struct audit_tree *owner;
853    struct list_head *postponed = audit_killed_trees();
854    int need_prune = 0;
855    int n;
856
857    if (chunk->dead)
858        return;
859
860    chunk->dead = 1;
861    mutex_lock(&audit_filter_mutex);
862    spin_lock(&hash_lock);
863    while (!list_empty(&chunk->trees)) {
864        owner = list_entry(chunk->trees.next,
865                   struct audit_tree, same_root);
866        owner->goner = 1;
867        owner->root = NULL;
868        list_del_init(&owner->same_root);
869        spin_unlock(&hash_lock);
870        if (!postponed) {
871            kill_rules(owner);
872            list_move(&owner->list, &prune_list);
873            need_prune = 1;
874        } else {
875            list_move(&owner->list, postponed);
876        }
877        spin_lock(&hash_lock);
878    }
879    list_del_rcu(&chunk->hash);
880    for (n = 0; n < chunk->count; n++)
881        list_del_init(&chunk->owners[n].list);
882    spin_unlock(&hash_lock);
883    if (need_prune)
884        audit_schedule_prune();
885    mutex_unlock(&audit_filter_mutex);
886}
887
888static void handle_event(struct inotify_watch *watch, u32 wd, u32 mask,
889                         u32 cookie, const char *dname, struct inode *inode)
890{
891    struct audit_chunk *chunk = container_of(watch, struct audit_chunk, watch);
892
893    if (mask & IN_IGNORED) {
894        evict_chunk(chunk);
895        put_inotify_watch(watch);
896    }
897}
898
899static void destroy_watch(struct inotify_watch *watch)
900{
901    struct audit_chunk *chunk = container_of(watch, struct audit_chunk, watch);
902    call_rcu(&chunk->head, __put_chunk);
903}
904
905static const struct inotify_operations rtree_inotify_ops = {
906    .handle_event = handle_event,
907    .destroy_watch = destroy_watch,
908};
909
910static int __init audit_tree_init(void)
911{
912    int i;
913
914    rtree_ih = inotify_init(&rtree_inotify_ops);
915    if (IS_ERR(rtree_ih))
916        audit_panic("cannot initialize inotify handle for rectree watches");
917
918    for (i = 0; i < HASH_SIZE; i++)
919        INIT_LIST_HEAD(&chunk_hash_heads[i]);
920
921    return 0;
922}
923__initcall(audit_tree_init);
924

Archive Download this file



interactive