Root/kernel/auditfilter.c

1/* auditfilter.c -- filtering of audit events
2 *
3 * Copyright 2003-2004 Red Hat, Inc.
4 * Copyright 2005 Hewlett-Packard Development Company, L.P.
5 * Copyright 2005 IBM Corporation
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 */
21
22#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
23
24#include <linux/kernel.h>
25#include <linux/audit.h>
26#include <linux/kthread.h>
27#include <linux/mutex.h>
28#include <linux/fs.h>
29#include <linux/namei.h>
30#include <linux/netlink.h>
31#include <linux/sched.h>
32#include <linux/slab.h>
33#include <linux/security.h>
34#include <net/net_namespace.h>
35#include <net/sock.h>
36#include "audit.h"
37
38/*
39 * Locking model:
40 *
41 * audit_filter_mutex:
42 * Synchronizes writes and blocking reads of audit's filterlist
43 * data. Rcu is used to traverse the filterlist and access
44 * contents of structs audit_entry, audit_watch and opaque
45 * LSM rules during filtering. If modified, these structures
46 * must be copied and replace their counterparts in the filterlist.
47 * An audit_parent struct is not accessed during filtering, so may
48 * be written directly provided audit_filter_mutex is held.
49 */
50
51/* Audit filter lists, defined in <linux/audit.h> */
52struct list_head audit_filter_list[AUDIT_NR_FILTERS] = {
53    LIST_HEAD_INIT(audit_filter_list[0]),
54    LIST_HEAD_INIT(audit_filter_list[1]),
55    LIST_HEAD_INIT(audit_filter_list[2]),
56    LIST_HEAD_INIT(audit_filter_list[3]),
57    LIST_HEAD_INIT(audit_filter_list[4]),
58    LIST_HEAD_INIT(audit_filter_list[5]),
59#if AUDIT_NR_FILTERS != 6
60#error Fix audit_filter_list initialiser
61#endif
62};
63static struct list_head audit_rules_list[AUDIT_NR_FILTERS] = {
64    LIST_HEAD_INIT(audit_rules_list[0]),
65    LIST_HEAD_INIT(audit_rules_list[1]),
66    LIST_HEAD_INIT(audit_rules_list[2]),
67    LIST_HEAD_INIT(audit_rules_list[3]),
68    LIST_HEAD_INIT(audit_rules_list[4]),
69    LIST_HEAD_INIT(audit_rules_list[5]),
70};
71
72DEFINE_MUTEX(audit_filter_mutex);
73
74static inline void audit_free_rule(struct audit_entry *e)
75{
76    int i;
77    struct audit_krule *erule = &e->rule;
78
79    /* some rules don't have associated watches */
80    if (erule->watch)
81        audit_put_watch(erule->watch);
82    if (erule->fields)
83        for (i = 0; i < erule->field_count; i++) {
84            struct audit_field *f = &erule->fields[i];
85            kfree(f->lsm_str);
86            security_audit_rule_free(f->lsm_rule);
87        }
88    kfree(erule->fields);
89    kfree(erule->filterkey);
90    kfree(e);
91}
92
93void audit_free_rule_rcu(struct rcu_head *head)
94{
95    struct audit_entry *e = container_of(head, struct audit_entry, rcu);
96    audit_free_rule(e);
97}
98
99/* Initialize an audit filterlist entry. */
100static inline struct audit_entry *audit_init_entry(u32 field_count)
101{
102    struct audit_entry *entry;
103    struct audit_field *fields;
104
105    entry = kzalloc(sizeof(*entry), GFP_KERNEL);
106    if (unlikely(!entry))
107        return NULL;
108
109    fields = kzalloc(sizeof(*fields) * field_count, GFP_KERNEL);
110    if (unlikely(!fields)) {
111        kfree(entry);
112        return NULL;
113    }
114    entry->rule.fields = fields;
115
116    return entry;
117}
118
119/* Unpack a filter field's string representation from user-space
120 * buffer. */
121char *audit_unpack_string(void **bufp, size_t *remain, size_t len)
122{
123    char *str;
124
125    if (!*bufp || (len == 0) || (len > *remain))
126        return ERR_PTR(-EINVAL);
127
128    /* Of the currently implemented string fields, PATH_MAX
129     * defines the longest valid length.
130     */
131    if (len > PATH_MAX)
132        return ERR_PTR(-ENAMETOOLONG);
133
134    str = kmalloc(len + 1, GFP_KERNEL);
135    if (unlikely(!str))
136        return ERR_PTR(-ENOMEM);
137
138    memcpy(str, *bufp, len);
139    str[len] = 0;
140    *bufp += len;
141    *remain -= len;
142
143    return str;
144}
145
146/* Translate an inode field to kernel respresentation. */
147static inline int audit_to_inode(struct audit_krule *krule,
148                 struct audit_field *f)
149{
150    if (krule->listnr != AUDIT_FILTER_EXIT ||
151        krule->watch || krule->inode_f || krule->tree ||
152        (f->op != Audit_equal && f->op != Audit_not_equal))
153        return -EINVAL;
154
155    krule->inode_f = f;
156    return 0;
157}
158
159static __u32 *classes[AUDIT_SYSCALL_CLASSES];
160
161int __init audit_register_class(int class, unsigned *list)
162{
163    __u32 *p = kzalloc(AUDIT_BITMASK_SIZE * sizeof(__u32), GFP_KERNEL);
164    if (!p)
165        return -ENOMEM;
166    while (*list != ~0U) {
167        unsigned n = *list++;
168        if (n >= AUDIT_BITMASK_SIZE * 32 - AUDIT_SYSCALL_CLASSES) {
169            kfree(p);
170            return -EINVAL;
171        }
172        p[AUDIT_WORD(n)] |= AUDIT_BIT(n);
173    }
174    if (class >= AUDIT_SYSCALL_CLASSES || classes[class]) {
175        kfree(p);
176        return -EINVAL;
177    }
178    classes[class] = p;
179    return 0;
180}
181
182int audit_match_class(int class, unsigned syscall)
183{
184    if (unlikely(syscall >= AUDIT_BITMASK_SIZE * 32))
185        return 0;
186    if (unlikely(class >= AUDIT_SYSCALL_CLASSES || !classes[class]))
187        return 0;
188    return classes[class][AUDIT_WORD(syscall)] & AUDIT_BIT(syscall);
189}
190
191#ifdef CONFIG_AUDITSYSCALL
192static inline int audit_match_class_bits(int class, u32 *mask)
193{
194    int i;
195
196    if (classes[class]) {
197        for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
198            if (mask[i] & classes[class][i])
199                return 0;
200    }
201    return 1;
202}
203
204static int audit_match_signal(struct audit_entry *entry)
205{
206    struct audit_field *arch = entry->rule.arch_f;
207
208    if (!arch) {
209        /* When arch is unspecified, we must check both masks on biarch
210         * as syscall number alone is ambiguous. */
211        return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
212                           entry->rule.mask) &&
213            audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
214                           entry->rule.mask));
215    }
216
217    switch(audit_classify_arch(arch->val)) {
218    case 0: /* native */
219        return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
220                           entry->rule.mask));
221    case 1: /* 32bit on biarch */
222        return (audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
223                           entry->rule.mask));
224    default:
225        return 1;
226    }
227}
228#endif
229
230/* Common user-space to kernel rule translation. */
231static inline struct audit_entry *audit_to_entry_common(struct audit_rule_data *rule)
232{
233    unsigned listnr;
234    struct audit_entry *entry;
235    int i, err;
236
237    err = -EINVAL;
238    listnr = rule->flags & ~AUDIT_FILTER_PREPEND;
239    switch(listnr) {
240    default:
241        goto exit_err;
242#ifdef CONFIG_AUDITSYSCALL
243    case AUDIT_FILTER_ENTRY:
244        if (rule->action == AUDIT_ALWAYS)
245            goto exit_err;
246    case AUDIT_FILTER_EXIT:
247    case AUDIT_FILTER_TASK:
248#endif
249    case AUDIT_FILTER_USER:
250    case AUDIT_FILTER_TYPE:
251        ;
252    }
253    if (unlikely(rule->action == AUDIT_POSSIBLE)) {
254        pr_err("AUDIT_POSSIBLE is deprecated\n");
255        goto exit_err;
256    }
257    if (rule->action != AUDIT_NEVER && rule->action != AUDIT_ALWAYS)
258        goto exit_err;
259    if (rule->field_count > AUDIT_MAX_FIELDS)
260        goto exit_err;
261
262    err = -ENOMEM;
263    entry = audit_init_entry(rule->field_count);
264    if (!entry)
265        goto exit_err;
266
267    entry->rule.flags = rule->flags & AUDIT_FILTER_PREPEND;
268    entry->rule.listnr = listnr;
269    entry->rule.action = rule->action;
270    entry->rule.field_count = rule->field_count;
271
272    for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
273        entry->rule.mask[i] = rule->mask[i];
274
275    for (i = 0; i < AUDIT_SYSCALL_CLASSES; i++) {
276        int bit = AUDIT_BITMASK_SIZE * 32 - i - 1;
277        __u32 *p = &entry->rule.mask[AUDIT_WORD(bit)];
278        __u32 *class;
279
280        if (!(*p & AUDIT_BIT(bit)))
281            continue;
282        *p &= ~AUDIT_BIT(bit);
283        class = classes[i];
284        if (class) {
285            int j;
286            for (j = 0; j < AUDIT_BITMASK_SIZE; j++)
287                entry->rule.mask[j] |= class[j];
288        }
289    }
290
291    return entry;
292
293exit_err:
294    return ERR_PTR(err);
295}
296
297static u32 audit_ops[] =
298{
299    [Audit_equal] = AUDIT_EQUAL,
300    [Audit_not_equal] = AUDIT_NOT_EQUAL,
301    [Audit_bitmask] = AUDIT_BIT_MASK,
302    [Audit_bittest] = AUDIT_BIT_TEST,
303    [Audit_lt] = AUDIT_LESS_THAN,
304    [Audit_gt] = AUDIT_GREATER_THAN,
305    [Audit_le] = AUDIT_LESS_THAN_OR_EQUAL,
306    [Audit_ge] = AUDIT_GREATER_THAN_OR_EQUAL,
307};
308
309static u32 audit_to_op(u32 op)
310{
311    u32 n;
312    for (n = Audit_equal; n < Audit_bad && audit_ops[n] != op; n++)
313        ;
314    return n;
315}
316
317/* check if an audit field is valid */
318static int audit_field_valid(struct audit_entry *entry, struct audit_field *f)
319{
320    switch(f->type) {
321    case AUDIT_MSGTYPE:
322        if (entry->rule.listnr != AUDIT_FILTER_TYPE &&
323            entry->rule.listnr != AUDIT_FILTER_USER)
324            return -EINVAL;
325        break;
326    };
327
328    switch(f->type) {
329    default:
330        return -EINVAL;
331    case AUDIT_UID:
332    case AUDIT_EUID:
333    case AUDIT_SUID:
334    case AUDIT_FSUID:
335    case AUDIT_LOGINUID:
336    case AUDIT_OBJ_UID:
337    case AUDIT_GID:
338    case AUDIT_EGID:
339    case AUDIT_SGID:
340    case AUDIT_FSGID:
341    case AUDIT_OBJ_GID:
342    case AUDIT_PID:
343    case AUDIT_PERS:
344    case AUDIT_MSGTYPE:
345    case AUDIT_PPID:
346    case AUDIT_DEVMAJOR:
347    case AUDIT_DEVMINOR:
348    case AUDIT_EXIT:
349    case AUDIT_SUCCESS:
350    case AUDIT_INODE:
351        /* bit ops are only useful on syscall args */
352        if (f->op == Audit_bitmask || f->op == Audit_bittest)
353            return -EINVAL;
354        break;
355    case AUDIT_ARG0:
356    case AUDIT_ARG1:
357    case AUDIT_ARG2:
358    case AUDIT_ARG3:
359    case AUDIT_SUBJ_USER:
360    case AUDIT_SUBJ_ROLE:
361    case AUDIT_SUBJ_TYPE:
362    case AUDIT_SUBJ_SEN:
363    case AUDIT_SUBJ_CLR:
364    case AUDIT_OBJ_USER:
365    case AUDIT_OBJ_ROLE:
366    case AUDIT_OBJ_TYPE:
367    case AUDIT_OBJ_LEV_LOW:
368    case AUDIT_OBJ_LEV_HIGH:
369    case AUDIT_WATCH:
370    case AUDIT_DIR:
371    case AUDIT_FILTERKEY:
372        break;
373    case AUDIT_LOGINUID_SET:
374        if ((f->val != 0) && (f->val != 1))
375            return -EINVAL;
376    /* FALL THROUGH */
377    case AUDIT_ARCH:
378        if (f->op != Audit_not_equal && f->op != Audit_equal)
379            return -EINVAL;
380        break;
381    case AUDIT_PERM:
382        if (f->val & ~15)
383            return -EINVAL;
384        break;
385    case AUDIT_FILETYPE:
386        if (f->val & ~S_IFMT)
387            return -EINVAL;
388        break;
389    case AUDIT_FIELD_COMPARE:
390        if (f->val > AUDIT_MAX_FIELD_COMPARE)
391            return -EINVAL;
392        break;
393    };
394    return 0;
395}
396
397/* Translate struct audit_rule_data to kernel's rule respresentation. */
398static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
399                           size_t datasz)
400{
401    int err = 0;
402    struct audit_entry *entry;
403    void *bufp;
404    size_t remain = datasz - sizeof(struct audit_rule_data);
405    int i;
406    char *str;
407
408    entry = audit_to_entry_common(data);
409    if (IS_ERR(entry))
410        goto exit_nofree;
411
412    bufp = data->buf;
413    entry->rule.vers_ops = 2;
414    for (i = 0; i < data->field_count; i++) {
415        struct audit_field *f = &entry->rule.fields[i];
416
417        err = -EINVAL;
418
419        f->op = audit_to_op(data->fieldflags[i]);
420        if (f->op == Audit_bad)
421            goto exit_free;
422
423        f->type = data->fields[i];
424        f->val = data->values[i];
425        f->uid = INVALID_UID;
426        f->gid = INVALID_GID;
427        f->lsm_str = NULL;
428        f->lsm_rule = NULL;
429
430        /* Support legacy tests for a valid loginuid */
431        if ((f->type == AUDIT_LOGINUID) && (f->val == AUDIT_UID_UNSET)) {
432            f->type = AUDIT_LOGINUID_SET;
433            f->val = 0;
434        }
435
436        if ((f->type == AUDIT_PID) || (f->type == AUDIT_PPID)) {
437            struct pid *pid;
438            rcu_read_lock();
439            pid = find_vpid(f->val);
440            if (!pid) {
441                rcu_read_unlock();
442                err = -ESRCH;
443                goto exit_free;
444            }
445            f->val = pid_nr(pid);
446            rcu_read_unlock();
447        }
448
449        err = audit_field_valid(entry, f);
450        if (err)
451            goto exit_free;
452
453        err = -EINVAL;
454        switch (f->type) {
455        case AUDIT_LOGINUID:
456        case AUDIT_UID:
457        case AUDIT_EUID:
458        case AUDIT_SUID:
459        case AUDIT_FSUID:
460        case AUDIT_OBJ_UID:
461            f->uid = make_kuid(current_user_ns(), f->val);
462            if (!uid_valid(f->uid))
463                goto exit_free;
464            break;
465        case AUDIT_GID:
466        case AUDIT_EGID:
467        case AUDIT_SGID:
468        case AUDIT_FSGID:
469        case AUDIT_OBJ_GID:
470            f->gid = make_kgid(current_user_ns(), f->val);
471            if (!gid_valid(f->gid))
472                goto exit_free;
473            break;
474        case AUDIT_ARCH:
475            entry->rule.arch_f = f;
476            break;
477        case AUDIT_SUBJ_USER:
478        case AUDIT_SUBJ_ROLE:
479        case AUDIT_SUBJ_TYPE:
480        case AUDIT_SUBJ_SEN:
481        case AUDIT_SUBJ_CLR:
482        case AUDIT_OBJ_USER:
483        case AUDIT_OBJ_ROLE:
484        case AUDIT_OBJ_TYPE:
485        case AUDIT_OBJ_LEV_LOW:
486        case AUDIT_OBJ_LEV_HIGH:
487            str = audit_unpack_string(&bufp, &remain, f->val);
488            if (IS_ERR(str))
489                goto exit_free;
490            entry->rule.buflen += f->val;
491
492            err = security_audit_rule_init(f->type, f->op, str,
493                               (void **)&f->lsm_rule);
494            /* Keep currently invalid fields around in case they
495             * become valid after a policy reload. */
496            if (err == -EINVAL) {
497                pr_warn("audit rule for LSM \'%s\' is invalid\n",
498                    str);
499                err = 0;
500            }
501            if (err) {
502                kfree(str);
503                goto exit_free;
504            } else
505                f->lsm_str = str;
506            break;
507        case AUDIT_WATCH:
508            str = audit_unpack_string(&bufp, &remain, f->val);
509            if (IS_ERR(str))
510                goto exit_free;
511            entry->rule.buflen += f->val;
512
513            err = audit_to_watch(&entry->rule, str, f->val, f->op);
514            if (err) {
515                kfree(str);
516                goto exit_free;
517            }
518            break;
519        case AUDIT_DIR:
520            str = audit_unpack_string(&bufp, &remain, f->val);
521            if (IS_ERR(str))
522                goto exit_free;
523            entry->rule.buflen += f->val;
524
525            err = audit_make_tree(&entry->rule, str, f->op);
526            kfree(str);
527            if (err)
528                goto exit_free;
529            break;
530        case AUDIT_INODE:
531            err = audit_to_inode(&entry->rule, f);
532            if (err)
533                goto exit_free;
534            break;
535        case AUDIT_FILTERKEY:
536            if (entry->rule.filterkey || f->val > AUDIT_MAX_KEY_LEN)
537                goto exit_free;
538            str = audit_unpack_string(&bufp, &remain, f->val);
539            if (IS_ERR(str))
540                goto exit_free;
541            entry->rule.buflen += f->val;
542            entry->rule.filterkey = str;
543            break;
544        }
545    }
546
547    if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal)
548        entry->rule.inode_f = NULL;
549
550exit_nofree:
551    return entry;
552
553exit_free:
554    if (entry->rule.watch)
555        audit_put_watch(entry->rule.watch); /* matches initial get */
556    if (entry->rule.tree)
557        audit_put_tree(entry->rule.tree); /* that's the temporary one */
558    audit_free_rule(entry);
559    return ERR_PTR(err);
560}
561
562/* Pack a filter field's string representation into data block. */
563static inline size_t audit_pack_string(void **bufp, const char *str)
564{
565    size_t len = strlen(str);
566
567    memcpy(*bufp, str, len);
568    *bufp += len;
569
570    return len;
571}
572
573/* Translate kernel rule respresentation to struct audit_rule_data. */
574static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule)
575{
576    struct audit_rule_data *data;
577    void *bufp;
578    int i;
579
580    data = kmalloc(sizeof(*data) + krule->buflen, GFP_KERNEL);
581    if (unlikely(!data))
582        return NULL;
583    memset(data, 0, sizeof(*data));
584
585    data->flags = krule->flags | krule->listnr;
586    data->action = krule->action;
587    data->field_count = krule->field_count;
588    bufp = data->buf;
589    for (i = 0; i < data->field_count; i++) {
590        struct audit_field *f = &krule->fields[i];
591
592        data->fields[i] = f->type;
593        data->fieldflags[i] = audit_ops[f->op];
594        switch(f->type) {
595        case AUDIT_SUBJ_USER:
596        case AUDIT_SUBJ_ROLE:
597        case AUDIT_SUBJ_TYPE:
598        case AUDIT_SUBJ_SEN:
599        case AUDIT_SUBJ_CLR:
600        case AUDIT_OBJ_USER:
601        case AUDIT_OBJ_ROLE:
602        case AUDIT_OBJ_TYPE:
603        case AUDIT_OBJ_LEV_LOW:
604        case AUDIT_OBJ_LEV_HIGH:
605            data->buflen += data->values[i] =
606                audit_pack_string(&bufp, f->lsm_str);
607            break;
608        case AUDIT_WATCH:
609            data->buflen += data->values[i] =
610                audit_pack_string(&bufp,
611                          audit_watch_path(krule->watch));
612            break;
613        case AUDIT_DIR:
614            data->buflen += data->values[i] =
615                audit_pack_string(&bufp,
616                          audit_tree_path(krule->tree));
617            break;
618        case AUDIT_FILTERKEY:
619            data->buflen += data->values[i] =
620                audit_pack_string(&bufp, krule->filterkey);
621            break;
622        default:
623            data->values[i] = f->val;
624        }
625    }
626    for (i = 0; i < AUDIT_BITMASK_SIZE; i++) data->mask[i] = krule->mask[i];
627
628    return data;
629}
630
631/* Compare two rules in kernel format. Considered success if rules
632 * don't match. */
633static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b)
634{
635    int i;
636
637    if (a->flags != b->flags ||
638        a->listnr != b->listnr ||
639        a->action != b->action ||
640        a->field_count != b->field_count)
641        return 1;
642
643    for (i = 0; i < a->field_count; i++) {
644        if (a->fields[i].type != b->fields[i].type ||
645            a->fields[i].op != b->fields[i].op)
646            return 1;
647
648        switch(a->fields[i].type) {
649        case AUDIT_SUBJ_USER:
650        case AUDIT_SUBJ_ROLE:
651        case AUDIT_SUBJ_TYPE:
652        case AUDIT_SUBJ_SEN:
653        case AUDIT_SUBJ_CLR:
654        case AUDIT_OBJ_USER:
655        case AUDIT_OBJ_ROLE:
656        case AUDIT_OBJ_TYPE:
657        case AUDIT_OBJ_LEV_LOW:
658        case AUDIT_OBJ_LEV_HIGH:
659            if (strcmp(a->fields[i].lsm_str, b->fields[i].lsm_str))
660                return 1;
661            break;
662        case AUDIT_WATCH:
663            if (strcmp(audit_watch_path(a->watch),
664                   audit_watch_path(b->watch)))
665                return 1;
666            break;
667        case AUDIT_DIR:
668            if (strcmp(audit_tree_path(a->tree),
669                   audit_tree_path(b->tree)))
670                return 1;
671            break;
672        case AUDIT_FILTERKEY:
673            /* both filterkeys exist based on above type compare */
674            if (strcmp(a->filterkey, b->filterkey))
675                return 1;
676            break;
677        case AUDIT_UID:
678        case AUDIT_EUID:
679        case AUDIT_SUID:
680        case AUDIT_FSUID:
681        case AUDIT_LOGINUID:
682        case AUDIT_OBJ_UID:
683            if (!uid_eq(a->fields[i].uid, b->fields[i].uid))
684                return 1;
685            break;
686        case AUDIT_GID:
687        case AUDIT_EGID:
688        case AUDIT_SGID:
689        case AUDIT_FSGID:
690        case AUDIT_OBJ_GID:
691            if (!gid_eq(a->fields[i].gid, b->fields[i].gid))
692                return 1;
693            break;
694        default:
695            if (a->fields[i].val != b->fields[i].val)
696                return 1;
697        }
698    }
699
700    for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
701        if (a->mask[i] != b->mask[i])
702            return 1;
703
704    return 0;
705}
706
707/* Duplicate LSM field information. The lsm_rule is opaque, so must be
708 * re-initialized. */
709static inline int audit_dupe_lsm_field(struct audit_field *df,
710                       struct audit_field *sf)
711{
712    int ret = 0;
713    char *lsm_str;
714
715    /* our own copy of lsm_str */
716    lsm_str = kstrdup(sf->lsm_str, GFP_KERNEL);
717    if (unlikely(!lsm_str))
718        return -ENOMEM;
719    df->lsm_str = lsm_str;
720
721    /* our own (refreshed) copy of lsm_rule */
722    ret = security_audit_rule_init(df->type, df->op, df->lsm_str,
723                       (void **)&df->lsm_rule);
724    /* Keep currently invalid fields around in case they
725     * become valid after a policy reload. */
726    if (ret == -EINVAL) {
727        pr_warn("audit rule for LSM \'%s\' is invalid\n",
728            df->lsm_str);
729        ret = 0;
730    }
731
732    return ret;
733}
734
735/* Duplicate an audit rule. This will be a deep copy with the exception
736 * of the watch - that pointer is carried over. The LSM specific fields
737 * will be updated in the copy. The point is to be able to replace the old
738 * rule with the new rule in the filterlist, then free the old rule.
739 * The rlist element is undefined; list manipulations are handled apart from
740 * the initial copy. */
741struct audit_entry *audit_dupe_rule(struct audit_krule *old)
742{
743    u32 fcount = old->field_count;
744    struct audit_entry *entry;
745    struct audit_krule *new;
746    char *fk;
747    int i, err = 0;
748
749    entry = audit_init_entry(fcount);
750    if (unlikely(!entry))
751        return ERR_PTR(-ENOMEM);
752
753    new = &entry->rule;
754    new->vers_ops = old->vers_ops;
755    new->flags = old->flags;
756    new->listnr = old->listnr;
757    new->action = old->action;
758    for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
759        new->mask[i] = old->mask[i];
760    new->prio = old->prio;
761    new->buflen = old->buflen;
762    new->inode_f = old->inode_f;
763    new->field_count = old->field_count;
764
765    /*
766     * note that we are OK with not refcounting here; audit_match_tree()
767     * never dereferences tree and we can't get false positives there
768     * since we'd have to have rule gone from the list *and* removed
769     * before the chunks found by lookup had been allocated, i.e. before
770     * the beginning of list scan.
771     */
772    new->tree = old->tree;
773    memcpy(new->fields, old->fields, sizeof(struct audit_field) * fcount);
774
775    /* deep copy this information, updating the lsm_rule fields, because
776     * the originals will all be freed when the old rule is freed. */
777    for (i = 0; i < fcount; i++) {
778        switch (new->fields[i].type) {
779        case AUDIT_SUBJ_USER:
780        case AUDIT_SUBJ_ROLE:
781        case AUDIT_SUBJ_TYPE:
782        case AUDIT_SUBJ_SEN:
783        case AUDIT_SUBJ_CLR:
784        case AUDIT_OBJ_USER:
785        case AUDIT_OBJ_ROLE:
786        case AUDIT_OBJ_TYPE:
787        case AUDIT_OBJ_LEV_LOW:
788        case AUDIT_OBJ_LEV_HIGH:
789            err = audit_dupe_lsm_field(&new->fields[i],
790                               &old->fields[i]);
791            break;
792        case AUDIT_FILTERKEY:
793            fk = kstrdup(old->filterkey, GFP_KERNEL);
794            if (unlikely(!fk))
795                err = -ENOMEM;
796            else
797                new->filterkey = fk;
798        }
799        if (err) {
800            audit_free_rule(entry);
801            return ERR_PTR(err);
802        }
803    }
804
805    if (old->watch) {
806        audit_get_watch(old->watch);
807        new->watch = old->watch;
808    }
809
810    return entry;
811}
812
813/* Find an existing audit rule.
814 * Caller must hold audit_filter_mutex to prevent stale rule data. */
815static struct audit_entry *audit_find_rule(struct audit_entry *entry,
816                       struct list_head **p)
817{
818    struct audit_entry *e, *found = NULL;
819    struct list_head *list;
820    int h;
821
822    if (entry->rule.inode_f) {
823        h = audit_hash_ino(entry->rule.inode_f->val);
824        *p = list = &audit_inode_hash[h];
825    } else if (entry->rule.watch) {
826        /* we don't know the inode number, so must walk entire hash */
827        for (h = 0; h < AUDIT_INODE_BUCKETS; h++) {
828            list = &audit_inode_hash[h];
829            list_for_each_entry(e, list, list)
830                if (!audit_compare_rule(&entry->rule, &e->rule)) {
831                    found = e;
832                    goto out;
833                }
834        }
835        goto out;
836    } else {
837        *p = list = &audit_filter_list[entry->rule.listnr];
838    }
839
840    list_for_each_entry(e, list, list)
841        if (!audit_compare_rule(&entry->rule, &e->rule)) {
842            found = e;
843            goto out;
844        }
845
846out:
847    return found;
848}
849
850static u64 prio_low = ~0ULL/2;
851static u64 prio_high = ~0ULL/2 - 1;
852
853/* Add rule to given filterlist if not a duplicate. */
854static inline int audit_add_rule(struct audit_entry *entry)
855{
856    struct audit_entry *e;
857    struct audit_watch *watch = entry->rule.watch;
858    struct audit_tree *tree = entry->rule.tree;
859    struct list_head *list;
860    int err;
861#ifdef CONFIG_AUDITSYSCALL
862    int dont_count = 0;
863
864    /* If either of these, don't count towards total */
865    if (entry->rule.listnr == AUDIT_FILTER_USER ||
866        entry->rule.listnr == AUDIT_FILTER_TYPE)
867        dont_count = 1;
868#endif
869
870    mutex_lock(&audit_filter_mutex);
871    e = audit_find_rule(entry, &list);
872    if (e) {
873        mutex_unlock(&audit_filter_mutex);
874        err = -EEXIST;
875        /* normally audit_add_tree_rule() will free it on failure */
876        if (tree)
877            audit_put_tree(tree);
878        goto error;
879    }
880
881    if (watch) {
882        /* audit_filter_mutex is dropped and re-taken during this call */
883        err = audit_add_watch(&entry->rule, &list);
884        if (err) {
885            mutex_unlock(&audit_filter_mutex);
886            /*
887             * normally audit_add_tree_rule() will free it
888             * on failure
889             */
890            if (tree)
891                audit_put_tree(tree);
892            goto error;
893        }
894    }
895    if (tree) {
896        err = audit_add_tree_rule(&entry->rule);
897        if (err) {
898            mutex_unlock(&audit_filter_mutex);
899            goto error;
900        }
901    }
902
903    entry->rule.prio = ~0ULL;
904    if (entry->rule.listnr == AUDIT_FILTER_EXIT) {
905        if (entry->rule.flags & AUDIT_FILTER_PREPEND)
906            entry->rule.prio = ++prio_high;
907        else
908            entry->rule.prio = --prio_low;
909    }
910
911    if (entry->rule.flags & AUDIT_FILTER_PREPEND) {
912        list_add(&entry->rule.list,
913             &audit_rules_list[entry->rule.listnr]);
914        list_add_rcu(&entry->list, list);
915        entry->rule.flags &= ~AUDIT_FILTER_PREPEND;
916    } else {
917        list_add_tail(&entry->rule.list,
918                  &audit_rules_list[entry->rule.listnr]);
919        list_add_tail_rcu(&entry->list, list);
920    }
921#ifdef CONFIG_AUDITSYSCALL
922    if (!dont_count)
923        audit_n_rules++;
924
925    if (!audit_match_signal(entry))
926        audit_signals++;
927#endif
928    mutex_unlock(&audit_filter_mutex);
929
930     return 0;
931
932error:
933    if (watch)
934        audit_put_watch(watch); /* tmp watch, matches initial get */
935    return err;
936}
937
938/* Remove an existing rule from filterlist. */
939static inline int audit_del_rule(struct audit_entry *entry)
940{
941    struct audit_entry *e;
942    struct audit_watch *watch = entry->rule.watch;
943    struct audit_tree *tree = entry->rule.tree;
944    struct list_head *list;
945    int ret = 0;
946#ifdef CONFIG_AUDITSYSCALL
947    int dont_count = 0;
948
949    /* If either of these, don't count towards total */
950    if (entry->rule.listnr == AUDIT_FILTER_USER ||
951        entry->rule.listnr == AUDIT_FILTER_TYPE)
952        dont_count = 1;
953#endif
954
955    mutex_lock(&audit_filter_mutex);
956    e = audit_find_rule(entry, &list);
957    if (!e) {
958        mutex_unlock(&audit_filter_mutex);
959        ret = -ENOENT;
960        goto out;
961    }
962
963    if (e->rule.watch)
964        audit_remove_watch_rule(&e->rule);
965
966    if (e->rule.tree)
967        audit_remove_tree_rule(&e->rule);
968
969    list_del_rcu(&e->list);
970    list_del(&e->rule.list);
971    call_rcu(&e->rcu, audit_free_rule_rcu);
972
973#ifdef CONFIG_AUDITSYSCALL
974    if (!dont_count)
975        audit_n_rules--;
976
977    if (!audit_match_signal(entry))
978        audit_signals--;
979#endif
980    mutex_unlock(&audit_filter_mutex);
981
982out:
983    if (watch)
984        audit_put_watch(watch); /* match initial get */
985    if (tree)
986        audit_put_tree(tree); /* that's the temporary one */
987
988    return ret;
989}
990
991/* List rules using struct audit_rule_data. */
992static void audit_list_rules(__u32 portid, int seq, struct sk_buff_head *q)
993{
994    struct sk_buff *skb;
995    struct audit_krule *r;
996    int i;
997
998    /* This is a blocking read, so use audit_filter_mutex instead of rcu
999     * iterator to sync with list writers. */
1000    for (i=0; i<AUDIT_NR_FILTERS; i++) {
1001        list_for_each_entry(r, &audit_rules_list[i], list) {
1002            struct audit_rule_data *data;
1003
1004            data = audit_krule_to_data(r);
1005            if (unlikely(!data))
1006                break;
1007            skb = audit_make_reply(portid, seq, AUDIT_LIST_RULES,
1008                           0, 1, data,
1009                           sizeof(*data) + data->buflen);
1010            if (skb)
1011                skb_queue_tail(q, skb);
1012            kfree(data);
1013        }
1014    }
1015    skb = audit_make_reply(portid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0);
1016    if (skb)
1017        skb_queue_tail(q, skb);
1018}
1019
1020/* Log rule additions and removals */
1021static void audit_log_rule_change(char *action, struct audit_krule *rule, int res)
1022{
1023    struct audit_buffer *ab;
1024    uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(current));
1025    unsigned int sessionid = audit_get_sessionid(current);
1026
1027    if (!audit_enabled)
1028        return;
1029
1030    ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
1031    if (!ab)
1032        return;
1033    audit_log_format(ab, "auid=%u ses=%u" ,loginuid, sessionid);
1034    audit_log_task_context(ab);
1035    audit_log_format(ab, " op=");
1036    audit_log_string(ab, action);
1037    audit_log_key(ab, rule->filterkey);
1038    audit_log_format(ab, " list=%d res=%d", rule->listnr, res);
1039    audit_log_end(ab);
1040}
1041
1042/**
1043 * audit_rule_change - apply all rules to the specified message type
1044 * @type: audit message type
1045 * @portid: target port id for netlink audit messages
1046 * @seq: netlink audit message sequence (serial) number
1047 * @data: payload data
1048 * @datasz: size of payload data
1049 */
1050int audit_rule_change(int type, __u32 portid, int seq, void *data,
1051            size_t datasz)
1052{
1053    int err = 0;
1054    struct audit_entry *entry;
1055
1056    switch (type) {
1057    case AUDIT_ADD_RULE:
1058        entry = audit_data_to_entry(data, datasz);
1059        if (IS_ERR(entry))
1060            return PTR_ERR(entry);
1061
1062        err = audit_add_rule(entry);
1063        audit_log_rule_change("add rule", &entry->rule, !err);
1064        if (err)
1065            audit_free_rule(entry);
1066        break;
1067    case AUDIT_DEL_RULE:
1068        entry = audit_data_to_entry(data, datasz);
1069        if (IS_ERR(entry))
1070            return PTR_ERR(entry);
1071
1072        err = audit_del_rule(entry);
1073        audit_log_rule_change("remove rule", &entry->rule, !err);
1074        audit_free_rule(entry);
1075        break;
1076    default:
1077        return -EINVAL;
1078    }
1079
1080    return err;
1081}
1082
1083/**
1084 * audit_list_rules_send - list the audit rules
1085 * @request_skb: skb of request we are replying to (used to target the reply)
1086 * @seq: netlink audit message sequence (serial) number
1087 */
1088int audit_list_rules_send(struct sk_buff *request_skb, int seq)
1089{
1090    u32 portid = NETLINK_CB(request_skb).portid;
1091    struct net *net = sock_net(NETLINK_CB(request_skb).sk);
1092    struct task_struct *tsk;
1093    struct audit_netlink_list *dest;
1094    int err = 0;
1095
1096    /* We can't just spew out the rules here because we might fill
1097     * the available socket buffer space and deadlock waiting for
1098     * auditctl to read from it... which isn't ever going to
1099     * happen if we're actually running in the context of auditctl
1100     * trying to _send_ the stuff */
1101
1102    dest = kmalloc(sizeof(struct audit_netlink_list), GFP_KERNEL);
1103    if (!dest)
1104        return -ENOMEM;
1105    dest->net = get_net(net);
1106    dest->portid = portid;
1107    skb_queue_head_init(&dest->q);
1108
1109    mutex_lock(&audit_filter_mutex);
1110    audit_list_rules(portid, seq, &dest->q);
1111    mutex_unlock(&audit_filter_mutex);
1112
1113    tsk = kthread_run(audit_send_list, dest, "audit_send_list");
1114    if (IS_ERR(tsk)) {
1115        skb_queue_purge(&dest->q);
1116        kfree(dest);
1117        err = PTR_ERR(tsk);
1118    }
1119
1120    return err;
1121}
1122
1123int audit_comparator(u32 left, u32 op, u32 right)
1124{
1125    switch (op) {
1126    case Audit_equal:
1127        return (left == right);
1128    case Audit_not_equal:
1129        return (left != right);
1130    case Audit_lt:
1131        return (left < right);
1132    case Audit_le:
1133        return (left <= right);
1134    case Audit_gt:
1135        return (left > right);
1136    case Audit_ge:
1137        return (left >= right);
1138    case Audit_bitmask:
1139        return (left & right);
1140    case Audit_bittest:
1141        return ((left & right) == right);
1142    default:
1143        BUG();
1144        return 0;
1145    }
1146}
1147
1148int audit_uid_comparator(kuid_t left, u32 op, kuid_t right)
1149{
1150    switch (op) {
1151    case Audit_equal:
1152        return uid_eq(left, right);
1153    case Audit_not_equal:
1154        return !uid_eq(left, right);
1155    case Audit_lt:
1156        return uid_lt(left, right);
1157    case Audit_le:
1158        return uid_lte(left, right);
1159    case Audit_gt:
1160        return uid_gt(left, right);
1161    case Audit_ge:
1162        return uid_gte(left, right);
1163    case Audit_bitmask:
1164    case Audit_bittest:
1165    default:
1166        BUG();
1167        return 0;
1168    }
1169}
1170
1171int audit_gid_comparator(kgid_t left, u32 op, kgid_t right)
1172{
1173    switch (op) {
1174    case Audit_equal:
1175        return gid_eq(left, right);
1176    case Audit_not_equal:
1177        return !gid_eq(left, right);
1178    case Audit_lt:
1179        return gid_lt(left, right);
1180    case Audit_le:
1181        return gid_lte(left, right);
1182    case Audit_gt:
1183        return gid_gt(left, right);
1184    case Audit_ge:
1185        return gid_gte(left, right);
1186    case Audit_bitmask:
1187    case Audit_bittest:
1188    default:
1189        BUG();
1190        return 0;
1191    }
1192}
1193
1194/**
1195 * parent_len - find the length of the parent portion of a pathname
1196 * @path: pathname of which to determine length
1197 */
1198int parent_len(const char *path)
1199{
1200    int plen;
1201    const char *p;
1202
1203    plen = strlen(path);
1204
1205    if (plen == 0)
1206        return plen;
1207
1208    /* disregard trailing slashes */
1209    p = path + plen - 1;
1210    while ((*p == '/') && (p > path))
1211        p--;
1212
1213    /* walk backward until we find the next slash or hit beginning */
1214    while ((*p != '/') && (p > path))
1215        p--;
1216
1217    /* did we find a slash? Then increment to include it in path */
1218    if (*p == '/')
1219        p++;
1220
1221    return p - path;
1222}
1223
1224/**
1225 * audit_compare_dname_path - compare given dentry name with last component in
1226 * given path. Return of 0 indicates a match.
1227 * @dname: dentry name that we're comparing
1228 * @path: full pathname that we're comparing
1229 * @parentlen: length of the parent if known. Passing in AUDIT_NAME_FULL
1230 * here indicates that we must compute this value.
1231 */
1232int audit_compare_dname_path(const char *dname, const char *path, int parentlen)
1233{
1234    int dlen, pathlen;
1235    const char *p;
1236
1237    dlen = strlen(dname);
1238    pathlen = strlen(path);
1239    if (pathlen < dlen)
1240        return 1;
1241
1242    parentlen = parentlen == AUDIT_NAME_FULL ? parent_len(path) : parentlen;
1243    if (pathlen - parentlen != dlen)
1244        return 1;
1245
1246    p = path + parentlen;
1247
1248    return strncmp(p, dname, dlen);
1249}
1250
1251static int audit_filter_user_rules(struct audit_krule *rule, int type,
1252                   enum audit_state *state)
1253{
1254    int i;
1255
1256    for (i = 0; i < rule->field_count; i++) {
1257        struct audit_field *f = &rule->fields[i];
1258        pid_t pid;
1259        int result = 0;
1260        u32 sid;
1261
1262        switch (f->type) {
1263        case AUDIT_PID:
1264            pid = task_pid_nr(current);
1265            result = audit_comparator(pid, f->op, f->val);
1266            break;
1267        case AUDIT_UID:
1268            result = audit_uid_comparator(current_uid(), f->op, f->uid);
1269            break;
1270        case AUDIT_GID:
1271            result = audit_gid_comparator(current_gid(), f->op, f->gid);
1272            break;
1273        case AUDIT_LOGINUID:
1274            result = audit_uid_comparator(audit_get_loginuid(current),
1275                          f->op, f->uid);
1276            break;
1277        case AUDIT_LOGINUID_SET:
1278            result = audit_comparator(audit_loginuid_set(current),
1279                          f->op, f->val);
1280            break;
1281        case AUDIT_MSGTYPE:
1282            result = audit_comparator(type, f->op, f->val);
1283            break;
1284        case AUDIT_SUBJ_USER:
1285        case AUDIT_SUBJ_ROLE:
1286        case AUDIT_SUBJ_TYPE:
1287        case AUDIT_SUBJ_SEN:
1288        case AUDIT_SUBJ_CLR:
1289            if (f->lsm_rule) {
1290                security_task_getsecid(current, &sid);
1291                result = security_audit_rule_match(sid,
1292                                   f->type,
1293                                   f->op,
1294                                   f->lsm_rule,
1295                                   NULL);
1296            }
1297            break;
1298        }
1299
1300        if (!result)
1301            return 0;
1302    }
1303    switch (rule->action) {
1304    case AUDIT_NEVER: *state = AUDIT_DISABLED; break;
1305    case AUDIT_ALWAYS: *state = AUDIT_RECORD_CONTEXT; break;
1306    }
1307    return 1;
1308}
1309
1310int audit_filter_user(int type)
1311{
1312    enum audit_state state = AUDIT_DISABLED;
1313    struct audit_entry *e;
1314    int rc, ret;
1315
1316    ret = 1; /* Audit by default */
1317
1318    rcu_read_lock();
1319    list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) {
1320        rc = audit_filter_user_rules(&e->rule, type, &state);
1321        if (rc) {
1322            if (rc > 0 && state == AUDIT_DISABLED)
1323                ret = 0;
1324            break;
1325        }
1326    }
1327    rcu_read_unlock();
1328
1329    return ret;
1330}
1331
1332int audit_filter_type(int type)
1333{
1334    struct audit_entry *e;
1335    int result = 0;
1336
1337    rcu_read_lock();
1338    if (list_empty(&audit_filter_list[AUDIT_FILTER_TYPE]))
1339        goto unlock_and_return;
1340
1341    list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE],
1342                list) {
1343        int i;
1344        for (i = 0; i < e->rule.field_count; i++) {
1345            struct audit_field *f = &e->rule.fields[i];
1346            if (f->type == AUDIT_MSGTYPE) {
1347                result = audit_comparator(type, f->op, f->val);
1348                if (!result)
1349                    break;
1350            }
1351        }
1352        if (result)
1353            goto unlock_and_return;
1354    }
1355unlock_and_return:
1356    rcu_read_unlock();
1357    return result;
1358}
1359
1360static int update_lsm_rule(struct audit_krule *r)
1361{
1362    struct audit_entry *entry = container_of(r, struct audit_entry, rule);
1363    struct audit_entry *nentry;
1364    int err = 0;
1365
1366    if (!security_audit_rule_known(r))
1367        return 0;
1368
1369    nentry = audit_dupe_rule(r);
1370    if (IS_ERR(nentry)) {
1371        /* save the first error encountered for the
1372         * return value */
1373        err = PTR_ERR(nentry);
1374        audit_panic("error updating LSM filters");
1375        if (r->watch)
1376            list_del(&r->rlist);
1377        list_del_rcu(&entry->list);
1378        list_del(&r->list);
1379    } else {
1380        if (r->watch || r->tree)
1381            list_replace_init(&r->rlist, &nentry->rule.rlist);
1382        list_replace_rcu(&entry->list, &nentry->list);
1383        list_replace(&r->list, &nentry->rule.list);
1384    }
1385    call_rcu(&entry->rcu, audit_free_rule_rcu);
1386
1387    return err;
1388}
1389
1390/* This function will re-initialize the lsm_rule field of all applicable rules.
1391 * It will traverse the filter lists serarching for rules that contain LSM
1392 * specific filter fields. When such a rule is found, it is copied, the
1393 * LSM field is re-initialized, and the old rule is replaced with the
1394 * updated rule. */
1395int audit_update_lsm_rules(void)
1396{
1397    struct audit_krule *r, *n;
1398    int i, err = 0;
1399
1400    /* audit_filter_mutex synchronizes the writers */
1401    mutex_lock(&audit_filter_mutex);
1402
1403    for (i = 0; i < AUDIT_NR_FILTERS; i++) {
1404        list_for_each_entry_safe(r, n, &audit_rules_list[i], list) {
1405            int res = update_lsm_rule(r);
1406            if (!err)
1407                err = res;
1408        }
1409    }
1410    mutex_unlock(&audit_filter_mutex);
1411
1412    return err;
1413}
1414

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