audit: allow matching on obj_uid
[linux-2.6.git] / 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 #include <linux/kernel.h>
23 #include <linux/audit.h>
24 #include <linux/kthread.h>
25 #include <linux/mutex.h>
26 #include <linux/fs.h>
27 #include <linux/namei.h>
28 #include <linux/netlink.h>
29 #include <linux/sched.h>
30 #include <linux/slab.h>
31 #include <linux/security.h>
32 #include "audit.h"
33
34 /*
35  * Locking model:
36  *
37  * audit_filter_mutex:
38  *              Synchronizes writes and blocking reads of audit's filterlist
39  *              data.  Rcu is used to traverse the filterlist and access
40  *              contents of structs audit_entry, audit_watch and opaque
41  *              LSM rules during filtering.  If modified, these structures
42  *              must be copied and replace their counterparts in the filterlist.
43  *              An audit_parent struct is not accessed during filtering, so may
44  *              be written directly provided audit_filter_mutex is held.
45  */
46
47 /* Audit filter lists, defined in <linux/audit.h> */
48 struct list_head audit_filter_list[AUDIT_NR_FILTERS] = {
49         LIST_HEAD_INIT(audit_filter_list[0]),
50         LIST_HEAD_INIT(audit_filter_list[1]),
51         LIST_HEAD_INIT(audit_filter_list[2]),
52         LIST_HEAD_INIT(audit_filter_list[3]),
53         LIST_HEAD_INIT(audit_filter_list[4]),
54         LIST_HEAD_INIT(audit_filter_list[5]),
55 #if AUDIT_NR_FILTERS != 6
56 #error Fix audit_filter_list initialiser
57 #endif
58 };
59 static struct list_head audit_rules_list[AUDIT_NR_FILTERS] = {
60         LIST_HEAD_INIT(audit_rules_list[0]),
61         LIST_HEAD_INIT(audit_rules_list[1]),
62         LIST_HEAD_INIT(audit_rules_list[2]),
63         LIST_HEAD_INIT(audit_rules_list[3]),
64         LIST_HEAD_INIT(audit_rules_list[4]),
65         LIST_HEAD_INIT(audit_rules_list[5]),
66 };
67
68 DEFINE_MUTEX(audit_filter_mutex);
69
70 static inline void audit_free_rule(struct audit_entry *e)
71 {
72         int i;
73         struct audit_krule *erule = &e->rule;
74
75         /* some rules don't have associated watches */
76         if (erule->watch)
77                 audit_put_watch(erule->watch);
78         if (erule->fields)
79                 for (i = 0; i < erule->field_count; i++) {
80                         struct audit_field *f = &erule->fields[i];
81                         kfree(f->lsm_str);
82                         security_audit_rule_free(f->lsm_rule);
83                 }
84         kfree(erule->fields);
85         kfree(erule->filterkey);
86         kfree(e);
87 }
88
89 void audit_free_rule_rcu(struct rcu_head *head)
90 {
91         struct audit_entry *e = container_of(head, struct audit_entry, rcu);
92         audit_free_rule(e);
93 }
94
95 /* Initialize an audit filterlist entry. */
96 static inline struct audit_entry *audit_init_entry(u32 field_count)
97 {
98         struct audit_entry *entry;
99         struct audit_field *fields;
100
101         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
102         if (unlikely(!entry))
103                 return NULL;
104
105         fields = kzalloc(sizeof(*fields) * field_count, GFP_KERNEL);
106         if (unlikely(!fields)) {
107                 kfree(entry);
108                 return NULL;
109         }
110         entry->rule.fields = fields;
111
112         return entry;
113 }
114
115 /* Unpack a filter field's string representation from user-space
116  * buffer. */
117 char *audit_unpack_string(void **bufp, size_t *remain, size_t len)
118 {
119         char *str;
120
121         if (!*bufp || (len == 0) || (len > *remain))
122                 return ERR_PTR(-EINVAL);
123
124         /* Of the currently implemented string fields, PATH_MAX
125          * defines the longest valid length.
126          */
127         if (len > PATH_MAX)
128                 return ERR_PTR(-ENAMETOOLONG);
129
130         str = kmalloc(len + 1, GFP_KERNEL);
131         if (unlikely(!str))
132                 return ERR_PTR(-ENOMEM);
133
134         memcpy(str, *bufp, len);
135         str[len] = 0;
136         *bufp += len;
137         *remain -= len;
138
139         return str;
140 }
141
142 /* Translate an inode field to kernel respresentation. */
143 static inline int audit_to_inode(struct audit_krule *krule,
144                                  struct audit_field *f)
145 {
146         if (krule->listnr != AUDIT_FILTER_EXIT ||
147             krule->watch || krule->inode_f || krule->tree ||
148             (f->op != Audit_equal && f->op != Audit_not_equal))
149                 return -EINVAL;
150
151         krule->inode_f = f;
152         return 0;
153 }
154
155 static __u32 *classes[AUDIT_SYSCALL_CLASSES];
156
157 int __init audit_register_class(int class, unsigned *list)
158 {
159         __u32 *p = kzalloc(AUDIT_BITMASK_SIZE * sizeof(__u32), GFP_KERNEL);
160         if (!p)
161                 return -ENOMEM;
162         while (*list != ~0U) {
163                 unsigned n = *list++;
164                 if (n >= AUDIT_BITMASK_SIZE * 32 - AUDIT_SYSCALL_CLASSES) {
165                         kfree(p);
166                         return -EINVAL;
167                 }
168                 p[AUDIT_WORD(n)] |= AUDIT_BIT(n);
169         }
170         if (class >= AUDIT_SYSCALL_CLASSES || classes[class]) {
171                 kfree(p);
172                 return -EINVAL;
173         }
174         classes[class] = p;
175         return 0;
176 }
177
178 int audit_match_class(int class, unsigned syscall)
179 {
180         if (unlikely(syscall >= AUDIT_BITMASK_SIZE * 32))
181                 return 0;
182         if (unlikely(class >= AUDIT_SYSCALL_CLASSES || !classes[class]))
183                 return 0;
184         return classes[class][AUDIT_WORD(syscall)] & AUDIT_BIT(syscall);
185 }
186
187 #ifdef CONFIG_AUDITSYSCALL
188 static inline int audit_match_class_bits(int class, u32 *mask)
189 {
190         int i;
191
192         if (classes[class]) {
193                 for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
194                         if (mask[i] & classes[class][i])
195                                 return 0;
196         }
197         return 1;
198 }
199
200 static int audit_match_signal(struct audit_entry *entry)
201 {
202         struct audit_field *arch = entry->rule.arch_f;
203
204         if (!arch) {
205                 /* When arch is unspecified, we must check both masks on biarch
206                  * as syscall number alone is ambiguous. */
207                 return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
208                                                entry->rule.mask) &&
209                         audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
210                                                entry->rule.mask));
211         }
212
213         switch(audit_classify_arch(arch->val)) {
214         case 0: /* native */
215                 return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
216                                                entry->rule.mask));
217         case 1: /* 32bit on biarch */
218                 return (audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
219                                                entry->rule.mask));
220         default:
221                 return 1;
222         }
223 }
224 #endif
225
226 /* Common user-space to kernel rule translation. */
227 static inline struct audit_entry *audit_to_entry_common(struct audit_rule *rule)
228 {
229         unsigned listnr;
230         struct audit_entry *entry;
231         int i, err;
232
233         err = -EINVAL;
234         listnr = rule->flags & ~AUDIT_FILTER_PREPEND;
235         switch(listnr) {
236         default:
237                 goto exit_err;
238 #ifdef CONFIG_AUDITSYSCALL
239         case AUDIT_FILTER_ENTRY:
240                 if (rule->action == AUDIT_ALWAYS)
241                         goto exit_err;
242         case AUDIT_FILTER_EXIT:
243         case AUDIT_FILTER_TASK:
244 #endif
245         case AUDIT_FILTER_USER:
246         case AUDIT_FILTER_TYPE:
247                 ;
248         }
249         if (unlikely(rule->action == AUDIT_POSSIBLE)) {
250                 printk(KERN_ERR "AUDIT_POSSIBLE is deprecated\n");
251                 goto exit_err;
252         }
253         if (rule->action != AUDIT_NEVER && rule->action != AUDIT_ALWAYS)
254                 goto exit_err;
255         if (rule->field_count > AUDIT_MAX_FIELDS)
256                 goto exit_err;
257
258         err = -ENOMEM;
259         entry = audit_init_entry(rule->field_count);
260         if (!entry)
261                 goto exit_err;
262
263         entry->rule.flags = rule->flags & AUDIT_FILTER_PREPEND;
264         entry->rule.listnr = listnr;
265         entry->rule.action = rule->action;
266         entry->rule.field_count = rule->field_count;
267
268         for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
269                 entry->rule.mask[i] = rule->mask[i];
270
271         for (i = 0; i < AUDIT_SYSCALL_CLASSES; i++) {
272                 int bit = AUDIT_BITMASK_SIZE * 32 - i - 1;
273                 __u32 *p = &entry->rule.mask[AUDIT_WORD(bit)];
274                 __u32 *class;
275
276                 if (!(*p & AUDIT_BIT(bit)))
277                         continue;
278                 *p &= ~AUDIT_BIT(bit);
279                 class = classes[i];
280                 if (class) {
281                         int j;
282                         for (j = 0; j < AUDIT_BITMASK_SIZE; j++)
283                                 entry->rule.mask[j] |= class[j];
284                 }
285         }
286
287         return entry;
288
289 exit_err:
290         return ERR_PTR(err);
291 }
292
293 static u32 audit_ops[] =
294 {
295         [Audit_equal] = AUDIT_EQUAL,
296         [Audit_not_equal] = AUDIT_NOT_EQUAL,
297         [Audit_bitmask] = AUDIT_BIT_MASK,
298         [Audit_bittest] = AUDIT_BIT_TEST,
299         [Audit_lt] = AUDIT_LESS_THAN,
300         [Audit_gt] = AUDIT_GREATER_THAN,
301         [Audit_le] = AUDIT_LESS_THAN_OR_EQUAL,
302         [Audit_ge] = AUDIT_GREATER_THAN_OR_EQUAL,
303 };
304
305 static u32 audit_to_op(u32 op)
306 {
307         u32 n;
308         for (n = Audit_equal; n < Audit_bad && audit_ops[n] != op; n++)
309                 ;
310         return n;
311 }
312
313
314 /* Translate struct audit_rule to kernel's rule respresentation.
315  * Exists for backward compatibility with userspace. */
316 static struct audit_entry *audit_rule_to_entry(struct audit_rule *rule)
317 {
318         struct audit_entry *entry;
319         int err = 0;
320         int i;
321
322         entry = audit_to_entry_common(rule);
323         if (IS_ERR(entry))
324                 goto exit_nofree;
325
326         for (i = 0; i < rule->field_count; i++) {
327                 struct audit_field *f = &entry->rule.fields[i];
328                 u32 n;
329
330                 n = rule->fields[i] & (AUDIT_NEGATE|AUDIT_OPERATORS);
331
332                 /* Support for legacy operators where
333                  * AUDIT_NEGATE bit signifies != and otherwise assumes == */
334                 if (n & AUDIT_NEGATE)
335                         f->op = Audit_not_equal;
336                 else if (!n)
337                         f->op = Audit_equal;
338                 else
339                         f->op = audit_to_op(n);
340
341                 entry->rule.vers_ops = (n & AUDIT_OPERATORS) ? 2 : 1;
342
343                 f->type = rule->fields[i] & ~(AUDIT_NEGATE|AUDIT_OPERATORS);
344                 f->val = rule->values[i];
345
346                 err = -EINVAL;
347                 if (f->op == Audit_bad)
348                         goto exit_free;
349
350                 switch(f->type) {
351                 default:
352                         goto exit_free;
353                 case AUDIT_PID:
354                 case AUDIT_UID:
355                 case AUDIT_EUID:
356                 case AUDIT_SUID:
357                 case AUDIT_FSUID:
358                 case AUDIT_GID:
359                 case AUDIT_EGID:
360                 case AUDIT_SGID:
361                 case AUDIT_FSGID:
362                 case AUDIT_LOGINUID:
363                 case AUDIT_PERS:
364                 case AUDIT_MSGTYPE:
365                 case AUDIT_PPID:
366                 case AUDIT_DEVMAJOR:
367                 case AUDIT_DEVMINOR:
368                 case AUDIT_EXIT:
369                 case AUDIT_SUCCESS:
370                         /* bit ops are only useful on syscall args */
371                         if (f->op == Audit_bitmask || f->op == Audit_bittest)
372                                 goto exit_free;
373                         break;
374                 case AUDIT_ARG0:
375                 case AUDIT_ARG1:
376                 case AUDIT_ARG2:
377                 case AUDIT_ARG3:
378                         break;
379                 /* arch is only allowed to be = or != */
380                 case AUDIT_ARCH:
381                         if (f->op != Audit_not_equal && f->op != Audit_equal)
382                                 goto exit_free;
383                         entry->rule.arch_f = f;
384                         break;
385                 case AUDIT_PERM:
386                         if (f->val & ~15)
387                                 goto exit_free;
388                         break;
389                 case AUDIT_FILETYPE:
390                         if (f->val & ~S_IFMT)
391                                 goto exit_free;
392                         break;
393                 case AUDIT_INODE:
394                         err = audit_to_inode(&entry->rule, f);
395                         if (err)
396                                 goto exit_free;
397                         break;
398                 }
399         }
400
401         if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal)
402                 entry->rule.inode_f = NULL;
403
404 exit_nofree:
405         return entry;
406
407 exit_free:
408         audit_free_rule(entry);
409         return ERR_PTR(err);
410 }
411
412 /* Translate struct audit_rule_data to kernel's rule respresentation. */
413 static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
414                                                size_t datasz)
415 {
416         int err = 0;
417         struct audit_entry *entry;
418         void *bufp;
419         size_t remain = datasz - sizeof(struct audit_rule_data);
420         int i;
421         char *str;
422
423         entry = audit_to_entry_common((struct audit_rule *)data);
424         if (IS_ERR(entry))
425                 goto exit_nofree;
426
427         bufp = data->buf;
428         entry->rule.vers_ops = 2;
429         for (i = 0; i < data->field_count; i++) {
430                 struct audit_field *f = &entry->rule.fields[i];
431
432                 err = -EINVAL;
433
434                 f->op = audit_to_op(data->fieldflags[i]);
435                 if (f->op == Audit_bad)
436                         goto exit_free;
437
438                 f->type = data->fields[i];
439                 f->val = data->values[i];
440                 f->lsm_str = NULL;
441                 f->lsm_rule = NULL;
442                 switch(f->type) {
443                 case AUDIT_PID:
444                 case AUDIT_UID:
445                 case AUDIT_EUID:
446                 case AUDIT_SUID:
447                 case AUDIT_FSUID:
448                 case AUDIT_GID:
449                 case AUDIT_EGID:
450                 case AUDIT_SGID:
451                 case AUDIT_FSGID:
452                 case AUDIT_LOGINUID:
453                 case AUDIT_PERS:
454                 case AUDIT_MSGTYPE:
455                 case AUDIT_PPID:
456                 case AUDIT_DEVMAJOR:
457                 case AUDIT_DEVMINOR:
458                 case AUDIT_EXIT:
459                 case AUDIT_SUCCESS:
460                 case AUDIT_ARG0:
461                 case AUDIT_ARG1:
462                 case AUDIT_ARG2:
463                 case AUDIT_ARG3:
464                 case AUDIT_OBJ_UID:
465                         break;
466                 case AUDIT_ARCH:
467                         entry->rule.arch_f = f;
468                         break;
469                 case AUDIT_SUBJ_USER:
470                 case AUDIT_SUBJ_ROLE:
471                 case AUDIT_SUBJ_TYPE:
472                 case AUDIT_SUBJ_SEN:
473                 case AUDIT_SUBJ_CLR:
474                 case AUDIT_OBJ_USER:
475                 case AUDIT_OBJ_ROLE:
476                 case AUDIT_OBJ_TYPE:
477                 case AUDIT_OBJ_LEV_LOW:
478                 case AUDIT_OBJ_LEV_HIGH:
479                         str = audit_unpack_string(&bufp, &remain, f->val);
480                         if (IS_ERR(str))
481                                 goto exit_free;
482                         entry->rule.buflen += f->val;
483
484                         err = security_audit_rule_init(f->type, f->op, str,
485                                                        (void **)&f->lsm_rule);
486                         /* Keep currently invalid fields around in case they
487                          * become valid after a policy reload. */
488                         if (err == -EINVAL) {
489                                 printk(KERN_WARNING "audit rule for LSM "
490                                        "\'%s\' is invalid\n",  str);
491                                 err = 0;
492                         }
493                         if (err) {
494                                 kfree(str);
495                                 goto exit_free;
496                         } else
497                                 f->lsm_str = str;
498                         break;
499                 case AUDIT_WATCH:
500                         str = audit_unpack_string(&bufp, &remain, f->val);
501                         if (IS_ERR(str))
502                                 goto exit_free;
503                         entry->rule.buflen += f->val;
504
505                         err = audit_to_watch(&entry->rule, str, f->val, f->op);
506                         if (err) {
507                                 kfree(str);
508                                 goto exit_free;
509                         }
510                         break;
511                 case AUDIT_DIR:
512                         str = audit_unpack_string(&bufp, &remain, f->val);
513                         if (IS_ERR(str))
514                                 goto exit_free;
515                         entry->rule.buflen += f->val;
516
517                         err = audit_make_tree(&entry->rule, str, f->op);
518                         kfree(str);
519                         if (err)
520                                 goto exit_free;
521                         break;
522                 case AUDIT_INODE:
523                         err = audit_to_inode(&entry->rule, f);
524                         if (err)
525                                 goto exit_free;
526                         break;
527                 case AUDIT_FILTERKEY:
528                         err = -EINVAL;
529                         if (entry->rule.filterkey || f->val > AUDIT_MAX_KEY_LEN)
530                                 goto exit_free;
531                         str = audit_unpack_string(&bufp, &remain, f->val);
532                         if (IS_ERR(str))
533                                 goto exit_free;
534                         entry->rule.buflen += f->val;
535                         entry->rule.filterkey = str;
536                         break;
537                 case AUDIT_PERM:
538                         if (f->val & ~15)
539                                 goto exit_free;
540                         break;
541                 case AUDIT_FILETYPE:
542                         if (f->val & ~S_IFMT)
543                                 goto exit_free;
544                         break;
545                 default:
546                         goto exit_free;
547                 }
548         }
549
550         if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal)
551                 entry->rule.inode_f = NULL;
552
553 exit_nofree:
554         return entry;
555
556 exit_free:
557         audit_free_rule(entry);
558         return ERR_PTR(err);
559 }
560
561 /* Pack a filter field's string representation into data block. */
562 static inline size_t audit_pack_string(void **bufp, const char *str)
563 {
564         size_t len = strlen(str);
565
566         memcpy(*bufp, str, len);
567         *bufp += len;
568
569         return len;
570 }
571
572 /* Translate kernel rule respresentation to struct audit_rule.
573  * Exists for backward compatibility with userspace. */
574 static struct audit_rule *audit_krule_to_rule(struct audit_krule *krule)
575 {
576         struct audit_rule *rule;
577         int i;
578
579         rule = kzalloc(sizeof(*rule), GFP_KERNEL);
580         if (unlikely(!rule))
581                 return NULL;
582
583         rule->flags = krule->flags | krule->listnr;
584         rule->action = krule->action;
585         rule->field_count = krule->field_count;
586         for (i = 0; i < rule->field_count; i++) {
587                 rule->values[i] = krule->fields[i].val;
588                 rule->fields[i] = krule->fields[i].type;
589
590                 if (krule->vers_ops == 1) {
591                         if (krule->fields[i].op == Audit_not_equal)
592                                 rule->fields[i] |= AUDIT_NEGATE;
593                 } else {
594                         rule->fields[i] |= audit_ops[krule->fields[i].op];
595                 }
596         }
597         for (i = 0; i < AUDIT_BITMASK_SIZE; i++) rule->mask[i] = krule->mask[i];
598
599         return rule;
600 }
601
602 /* Translate kernel rule respresentation to struct audit_rule_data. */
603 static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule)
604 {
605         struct audit_rule_data *data;
606         void *bufp;
607         int i;
608
609         data = kmalloc(sizeof(*data) + krule->buflen, GFP_KERNEL);
610         if (unlikely(!data))
611                 return NULL;
612         memset(data, 0, sizeof(*data));
613
614         data->flags = krule->flags | krule->listnr;
615         data->action = krule->action;
616         data->field_count = krule->field_count;
617         bufp = data->buf;
618         for (i = 0; i < data->field_count; i++) {
619                 struct audit_field *f = &krule->fields[i];
620
621                 data->fields[i] = f->type;
622                 data->fieldflags[i] = audit_ops[f->op];
623                 switch(f->type) {
624                 case AUDIT_SUBJ_USER:
625                 case AUDIT_SUBJ_ROLE:
626                 case AUDIT_SUBJ_TYPE:
627                 case AUDIT_SUBJ_SEN:
628                 case AUDIT_SUBJ_CLR:
629                 case AUDIT_OBJ_USER:
630                 case AUDIT_OBJ_ROLE:
631                 case AUDIT_OBJ_TYPE:
632                 case AUDIT_OBJ_LEV_LOW:
633                 case AUDIT_OBJ_LEV_HIGH:
634                         data->buflen += data->values[i] =
635                                 audit_pack_string(&bufp, f->lsm_str);
636                         break;
637                 case AUDIT_WATCH:
638                         data->buflen += data->values[i] =
639                                 audit_pack_string(&bufp,
640                                                   audit_watch_path(krule->watch));
641                         break;
642                 case AUDIT_DIR:
643                         data->buflen += data->values[i] =
644                                 audit_pack_string(&bufp,
645                                                   audit_tree_path(krule->tree));
646                         break;
647                 case AUDIT_FILTERKEY:
648                         data->buflen += data->values[i] =
649                                 audit_pack_string(&bufp, krule->filterkey);
650                         break;
651                 default:
652                         data->values[i] = f->val;
653                 }
654         }
655         for (i = 0; i < AUDIT_BITMASK_SIZE; i++) data->mask[i] = krule->mask[i];
656
657         return data;
658 }
659
660 /* Compare two rules in kernel format.  Considered success if rules
661  * don't match. */
662 static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b)
663 {
664         int i;
665
666         if (a->flags != b->flags ||
667             a->listnr != b->listnr ||
668             a->action != b->action ||
669             a->field_count != b->field_count)
670                 return 1;
671
672         for (i = 0; i < a->field_count; i++) {
673                 if (a->fields[i].type != b->fields[i].type ||
674                     a->fields[i].op != b->fields[i].op)
675                         return 1;
676
677                 switch(a->fields[i].type) {
678                 case AUDIT_SUBJ_USER:
679                 case AUDIT_SUBJ_ROLE:
680                 case AUDIT_SUBJ_TYPE:
681                 case AUDIT_SUBJ_SEN:
682                 case AUDIT_SUBJ_CLR:
683                 case AUDIT_OBJ_USER:
684                 case AUDIT_OBJ_ROLE:
685                 case AUDIT_OBJ_TYPE:
686                 case AUDIT_OBJ_LEV_LOW:
687                 case AUDIT_OBJ_LEV_HIGH:
688                         if (strcmp(a->fields[i].lsm_str, b->fields[i].lsm_str))
689                                 return 1;
690                         break;
691                 case AUDIT_WATCH:
692                         if (strcmp(audit_watch_path(a->watch),
693                                    audit_watch_path(b->watch)))
694                                 return 1;
695                         break;
696                 case AUDIT_DIR:
697                         if (strcmp(audit_tree_path(a->tree),
698                                    audit_tree_path(b->tree)))
699                                 return 1;
700                         break;
701                 case AUDIT_FILTERKEY:
702                         /* both filterkeys exist based on above type compare */
703                         if (strcmp(a->filterkey, b->filterkey))
704                                 return 1;
705                         break;
706                 default:
707                         if (a->fields[i].val != b->fields[i].val)
708                                 return 1;
709                 }
710         }
711
712         for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
713                 if (a->mask[i] != b->mask[i])
714                         return 1;
715
716         return 0;
717 }
718
719 /* Duplicate LSM field information.  The lsm_rule is opaque, so must be
720  * re-initialized. */
721 static inline int audit_dupe_lsm_field(struct audit_field *df,
722                                            struct audit_field *sf)
723 {
724         int ret = 0;
725         char *lsm_str;
726
727         /* our own copy of lsm_str */
728         lsm_str = kstrdup(sf->lsm_str, GFP_KERNEL);
729         if (unlikely(!lsm_str))
730                 return -ENOMEM;
731         df->lsm_str = lsm_str;
732
733         /* our own (refreshed) copy of lsm_rule */
734         ret = security_audit_rule_init(df->type, df->op, df->lsm_str,
735                                        (void **)&df->lsm_rule);
736         /* Keep currently invalid fields around in case they
737          * become valid after a policy reload. */
738         if (ret == -EINVAL) {
739                 printk(KERN_WARNING "audit rule for LSM \'%s\' is "
740                        "invalid\n", df->lsm_str);
741                 ret = 0;
742         }
743
744         return ret;
745 }
746
747 /* Duplicate an audit rule.  This will be a deep copy with the exception
748  * of the watch - that pointer is carried over.  The LSM specific fields
749  * will be updated in the copy.  The point is to be able to replace the old
750  * rule with the new rule in the filterlist, then free the old rule.
751  * The rlist element is undefined; list manipulations are handled apart from
752  * the initial copy. */
753 struct audit_entry *audit_dupe_rule(struct audit_krule *old)
754 {
755         u32 fcount = old->field_count;
756         struct audit_entry *entry;
757         struct audit_krule *new;
758         char *fk;
759         int i, err = 0;
760
761         entry = audit_init_entry(fcount);
762         if (unlikely(!entry))
763                 return ERR_PTR(-ENOMEM);
764
765         new = &entry->rule;
766         new->vers_ops = old->vers_ops;
767         new->flags = old->flags;
768         new->listnr = old->listnr;
769         new->action = old->action;
770         for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
771                 new->mask[i] = old->mask[i];
772         new->prio = old->prio;
773         new->buflen = old->buflen;
774         new->inode_f = old->inode_f;
775         new->field_count = old->field_count;
776
777         /*
778          * note that we are OK with not refcounting here; audit_match_tree()
779          * never dereferences tree and we can't get false positives there
780          * since we'd have to have rule gone from the list *and* removed
781          * before the chunks found by lookup had been allocated, i.e. before
782          * the beginning of list scan.
783          */
784         new->tree = old->tree;
785         memcpy(new->fields, old->fields, sizeof(struct audit_field) * fcount);
786
787         /* deep copy this information, updating the lsm_rule fields, because
788          * the originals will all be freed when the old rule is freed. */
789         for (i = 0; i < fcount; i++) {
790                 switch (new->fields[i].type) {
791                 case AUDIT_SUBJ_USER:
792                 case AUDIT_SUBJ_ROLE:
793                 case AUDIT_SUBJ_TYPE:
794                 case AUDIT_SUBJ_SEN:
795                 case AUDIT_SUBJ_CLR:
796                 case AUDIT_OBJ_USER:
797                 case AUDIT_OBJ_ROLE:
798                 case AUDIT_OBJ_TYPE:
799                 case AUDIT_OBJ_LEV_LOW:
800                 case AUDIT_OBJ_LEV_HIGH:
801                         err = audit_dupe_lsm_field(&new->fields[i],
802                                                        &old->fields[i]);
803                         break;
804                 case AUDIT_FILTERKEY:
805                         fk = kstrdup(old->filterkey, GFP_KERNEL);
806                         if (unlikely(!fk))
807                                 err = -ENOMEM;
808                         else
809                                 new->filterkey = fk;
810                 }
811                 if (err) {
812                         audit_free_rule(entry);
813                         return ERR_PTR(err);
814                 }
815         }
816
817         if (old->watch) {
818                 audit_get_watch(old->watch);
819                 new->watch = old->watch;
820         }
821
822         return entry;
823 }
824
825 /* Find an existing audit rule.
826  * Caller must hold audit_filter_mutex to prevent stale rule data. */
827 static struct audit_entry *audit_find_rule(struct audit_entry *entry,
828                                            struct list_head **p)
829 {
830         struct audit_entry *e, *found = NULL;
831         struct list_head *list;
832         int h;
833
834         if (entry->rule.inode_f) {
835                 h = audit_hash_ino(entry->rule.inode_f->val);
836                 *p = list = &audit_inode_hash[h];
837         } else if (entry->rule.watch) {
838                 /* we don't know the inode number, so must walk entire hash */
839                 for (h = 0; h < AUDIT_INODE_BUCKETS; h++) {
840                         list = &audit_inode_hash[h];
841                         list_for_each_entry(e, list, list)
842                                 if (!audit_compare_rule(&entry->rule, &e->rule)) {
843                                         found = e;
844                                         goto out;
845                                 }
846                 }
847                 goto out;
848         } else {
849                 *p = list = &audit_filter_list[entry->rule.listnr];
850         }
851
852         list_for_each_entry(e, list, list)
853                 if (!audit_compare_rule(&entry->rule, &e->rule)) {
854                         found = e;
855                         goto out;
856                 }
857
858 out:
859         return found;
860 }
861
862 static u64 prio_low = ~0ULL/2;
863 static u64 prio_high = ~0ULL/2 - 1;
864
865 /* Add rule to given filterlist if not a duplicate. */
866 static inline int audit_add_rule(struct audit_entry *entry)
867 {
868         struct audit_entry *e;
869         struct audit_watch *watch = entry->rule.watch;
870         struct audit_tree *tree = entry->rule.tree;
871         struct list_head *list;
872         int err;
873 #ifdef CONFIG_AUDITSYSCALL
874         int dont_count = 0;
875
876         /* If either of these, don't count towards total */
877         if (entry->rule.listnr == AUDIT_FILTER_USER ||
878                 entry->rule.listnr == AUDIT_FILTER_TYPE)
879                 dont_count = 1;
880 #endif
881
882         mutex_lock(&audit_filter_mutex);
883         e = audit_find_rule(entry, &list);
884         if (e) {
885                 mutex_unlock(&audit_filter_mutex);
886                 err = -EEXIST;
887                 /* normally audit_add_tree_rule() will free it on failure */
888                 if (tree)
889                         audit_put_tree(tree);
890                 goto error;
891         }
892
893         if (watch) {
894                 /* audit_filter_mutex is dropped and re-taken during this call */
895                 err = audit_add_watch(&entry->rule, &list);
896                 if (err) {
897                         mutex_unlock(&audit_filter_mutex);
898                         goto error;
899                 }
900         }
901         if (tree) {
902                 err = audit_add_tree_rule(&entry->rule);
903                 if (err) {
904                         mutex_unlock(&audit_filter_mutex);
905                         goto error;
906                 }
907         }
908
909         entry->rule.prio = ~0ULL;
910         if (entry->rule.listnr == AUDIT_FILTER_EXIT) {
911                 if (entry->rule.flags & AUDIT_FILTER_PREPEND)
912                         entry->rule.prio = ++prio_high;
913                 else
914                         entry->rule.prio = --prio_low;
915         }
916
917         if (entry->rule.flags & AUDIT_FILTER_PREPEND) {
918                 list_add(&entry->rule.list,
919                          &audit_rules_list[entry->rule.listnr]);
920                 list_add_rcu(&entry->list, list);
921                 entry->rule.flags &= ~AUDIT_FILTER_PREPEND;
922         } else {
923                 list_add_tail(&entry->rule.list,
924                               &audit_rules_list[entry->rule.listnr]);
925                 list_add_tail_rcu(&entry->list, list);
926         }
927 #ifdef CONFIG_AUDITSYSCALL
928         if (!dont_count)
929                 audit_n_rules++;
930
931         if (!audit_match_signal(entry))
932                 audit_signals++;
933 #endif
934         mutex_unlock(&audit_filter_mutex);
935
936         return 0;
937
938 error:
939         if (watch)
940                 audit_put_watch(watch); /* tmp watch, matches initial get */
941         return err;
942 }
943
944 /* Remove an existing rule from filterlist. */
945 static inline int audit_del_rule(struct audit_entry *entry)
946 {
947         struct audit_entry  *e;
948         struct audit_watch *watch = entry->rule.watch;
949         struct audit_tree *tree = entry->rule.tree;
950         struct list_head *list;
951         int ret = 0;
952 #ifdef CONFIG_AUDITSYSCALL
953         int dont_count = 0;
954
955         /* If either of these, don't count towards total */
956         if (entry->rule.listnr == AUDIT_FILTER_USER ||
957                 entry->rule.listnr == AUDIT_FILTER_TYPE)
958                 dont_count = 1;
959 #endif
960
961         mutex_lock(&audit_filter_mutex);
962         e = audit_find_rule(entry, &list);
963         if (!e) {
964                 mutex_unlock(&audit_filter_mutex);
965                 ret = -ENOENT;
966                 goto out;
967         }
968
969         if (e->rule.watch)
970                 audit_remove_watch_rule(&e->rule);
971
972         if (e->rule.tree)
973                 audit_remove_tree_rule(&e->rule);
974
975         list_del_rcu(&e->list);
976         list_del(&e->rule.list);
977         call_rcu(&e->rcu, audit_free_rule_rcu);
978
979 #ifdef CONFIG_AUDITSYSCALL
980         if (!dont_count)
981                 audit_n_rules--;
982
983         if (!audit_match_signal(entry))
984                 audit_signals--;
985 #endif
986         mutex_unlock(&audit_filter_mutex);
987
988 out:
989         if (watch)
990                 audit_put_watch(watch); /* match initial get */
991         if (tree)
992                 audit_put_tree(tree);   /* that's the temporary one */
993
994         return ret;
995 }
996
997 /* List rules using struct audit_rule.  Exists for backward
998  * compatibility with userspace. */
999 static void audit_list(int pid, int seq, struct sk_buff_head *q)
1000 {
1001         struct sk_buff *skb;
1002         struct audit_krule *r;
1003         int i;
1004
1005         /* This is a blocking read, so use audit_filter_mutex instead of rcu
1006          * iterator to sync with list writers. */
1007         for (i=0; i<AUDIT_NR_FILTERS; i++) {
1008                 list_for_each_entry(r, &audit_rules_list[i], list) {
1009                         struct audit_rule *rule;
1010
1011                         rule = audit_krule_to_rule(r);
1012                         if (unlikely(!rule))
1013                                 break;
1014                         skb = audit_make_reply(pid, seq, AUDIT_LIST, 0, 1,
1015                                          rule, sizeof(*rule));
1016                         if (skb)
1017                                 skb_queue_tail(q, skb);
1018                         kfree(rule);
1019                 }
1020         }
1021         skb = audit_make_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0);
1022         if (skb)
1023                 skb_queue_tail(q, skb);
1024 }
1025
1026 /* List rules using struct audit_rule_data. */
1027 static void audit_list_rules(int pid, int seq, struct sk_buff_head *q)
1028 {
1029         struct sk_buff *skb;
1030         struct audit_krule *r;
1031         int i;
1032
1033         /* This is a blocking read, so use audit_filter_mutex instead of rcu
1034          * iterator to sync with list writers. */
1035         for (i=0; i<AUDIT_NR_FILTERS; i++) {
1036                 list_for_each_entry(r, &audit_rules_list[i], list) {
1037                         struct audit_rule_data *data;
1038
1039                         data = audit_krule_to_data(r);
1040                         if (unlikely(!data))
1041                                 break;
1042                         skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 0, 1,
1043                                          data, sizeof(*data) + data->buflen);
1044                         if (skb)
1045                                 skb_queue_tail(q, skb);
1046                         kfree(data);
1047                 }
1048         }
1049         skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0);
1050         if (skb)
1051                 skb_queue_tail(q, skb);
1052 }
1053
1054 /* Log rule additions and removals */
1055 static void audit_log_rule_change(uid_t loginuid, u32 sessionid, u32 sid,
1056                                   char *action, struct audit_krule *rule,
1057                                   int res)
1058 {
1059         struct audit_buffer *ab;
1060
1061         if (!audit_enabled)
1062                 return;
1063
1064         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
1065         if (!ab)
1066                 return;
1067         audit_log_format(ab, "auid=%u ses=%u", loginuid, sessionid);
1068         if (sid) {
1069                 char *ctx = NULL;
1070                 u32 len;
1071                 if (security_secid_to_secctx(sid, &ctx, &len))
1072                         audit_log_format(ab, " ssid=%u", sid);
1073                 else {
1074                         audit_log_format(ab, " subj=%s", ctx);
1075                         security_release_secctx(ctx, len);
1076                 }
1077         }
1078         audit_log_format(ab, " op=");
1079         audit_log_string(ab, action);
1080         audit_log_key(ab, rule->filterkey);
1081         audit_log_format(ab, " list=%d res=%d", rule->listnr, res);
1082         audit_log_end(ab);
1083 }
1084
1085 /**
1086  * audit_receive_filter - apply all rules to the specified message type
1087  * @type: audit message type
1088  * @pid: target pid for netlink audit messages
1089  * @uid: target uid for netlink audit messages
1090  * @seq: netlink audit message sequence (serial) number
1091  * @data: payload data
1092  * @datasz: size of payload data
1093  * @loginuid: loginuid of sender
1094  * @sessionid: sessionid for netlink audit message
1095  * @sid: SE Linux Security ID of sender
1096  */
1097 int audit_receive_filter(int type, int pid, int uid, int seq, void *data,
1098                          size_t datasz, uid_t loginuid, u32 sessionid, u32 sid)
1099 {
1100         struct task_struct *tsk;
1101         struct audit_netlink_list *dest;
1102         int err = 0;
1103         struct audit_entry *entry;
1104
1105         switch (type) {
1106         case AUDIT_LIST:
1107         case AUDIT_LIST_RULES:
1108                 /* We can't just spew out the rules here because we might fill
1109                  * the available socket buffer space and deadlock waiting for
1110                  * auditctl to read from it... which isn't ever going to
1111                  * happen if we're actually running in the context of auditctl
1112                  * trying to _send_ the stuff */
1113
1114                 dest = kmalloc(sizeof(struct audit_netlink_list), GFP_KERNEL);
1115                 if (!dest)
1116                         return -ENOMEM;
1117                 dest->pid = pid;
1118                 skb_queue_head_init(&dest->q);
1119
1120                 mutex_lock(&audit_filter_mutex);
1121                 if (type == AUDIT_LIST)
1122                         audit_list(pid, seq, &dest->q);
1123                 else
1124                         audit_list_rules(pid, seq, &dest->q);
1125                 mutex_unlock(&audit_filter_mutex);
1126
1127                 tsk = kthread_run(audit_send_list, dest, "audit_send_list");
1128                 if (IS_ERR(tsk)) {
1129                         skb_queue_purge(&dest->q);
1130                         kfree(dest);
1131                         err = PTR_ERR(tsk);
1132                 }
1133                 break;
1134         case AUDIT_ADD:
1135         case AUDIT_ADD_RULE:
1136                 if (type == AUDIT_ADD)
1137                         entry = audit_rule_to_entry(data);
1138                 else
1139                         entry = audit_data_to_entry(data, datasz);
1140                 if (IS_ERR(entry))
1141                         return PTR_ERR(entry);
1142
1143                 err = audit_add_rule(entry);
1144                 audit_log_rule_change(loginuid, sessionid, sid, "add rule",
1145                                       &entry->rule, !err);
1146
1147                 if (err)
1148                         audit_free_rule(entry);
1149                 break;
1150         case AUDIT_DEL:
1151         case AUDIT_DEL_RULE:
1152                 if (type == AUDIT_DEL)
1153                         entry = audit_rule_to_entry(data);
1154                 else
1155                         entry = audit_data_to_entry(data, datasz);
1156                 if (IS_ERR(entry))
1157                         return PTR_ERR(entry);
1158
1159                 err = audit_del_rule(entry);
1160                 audit_log_rule_change(loginuid, sessionid, sid, "remove rule",
1161                                       &entry->rule, !err);
1162
1163                 audit_free_rule(entry);
1164                 break;
1165         default:
1166                 return -EINVAL;
1167         }
1168
1169         return err;
1170 }
1171
1172 int audit_comparator(u32 left, u32 op, u32 right)
1173 {
1174         switch (op) {
1175         case Audit_equal:
1176                 return (left == right);
1177         case Audit_not_equal:
1178                 return (left != right);
1179         case Audit_lt:
1180                 return (left < right);
1181         case Audit_le:
1182                 return (left <= right);
1183         case Audit_gt:
1184                 return (left > right);
1185         case Audit_ge:
1186                 return (left >= right);
1187         case Audit_bitmask:
1188                 return (left & right);
1189         case Audit_bittest:
1190                 return ((left & right) == right);
1191         default:
1192                 BUG();
1193                 return 0;
1194         }
1195 }
1196
1197 /* Compare given dentry name with last component in given path,
1198  * return of 0 indicates a match. */
1199 int audit_compare_dname_path(const char *dname, const char *path,
1200                              int *dirlen)
1201 {
1202         int dlen, plen;
1203         const char *p;
1204
1205         if (!dname || !path)
1206                 return 1;
1207
1208         dlen = strlen(dname);
1209         plen = strlen(path);
1210         if (plen < dlen)
1211                 return 1;
1212
1213         /* disregard trailing slashes */
1214         p = path + plen - 1;
1215         while ((*p == '/') && (p > path))
1216                 p--;
1217
1218         /* find last path component */
1219         p = p - dlen + 1;
1220         if (p < path)
1221                 return 1;
1222         else if (p > path) {
1223                 if (*--p != '/')
1224                         return 1;
1225                 else
1226                         p++;
1227         }
1228
1229         /* return length of path's directory component */
1230         if (dirlen)
1231                 *dirlen = p - path;
1232         return strncmp(p, dname, dlen);
1233 }
1234
1235 static int audit_filter_user_rules(struct netlink_skb_parms *cb,
1236                                    struct audit_krule *rule,
1237                                    enum audit_state *state)
1238 {
1239         int i;
1240
1241         for (i = 0; i < rule->field_count; i++) {
1242                 struct audit_field *f = &rule->fields[i];
1243                 int result = 0;
1244                 u32 sid;
1245
1246                 switch (f->type) {
1247                 case AUDIT_PID:
1248                         result = audit_comparator(cb->creds.pid, f->op, f->val);
1249                         break;
1250                 case AUDIT_UID:
1251                         result = audit_comparator(cb->creds.uid, f->op, f->val);
1252                         break;
1253                 case AUDIT_GID:
1254                         result = audit_comparator(cb->creds.gid, f->op, f->val);
1255                         break;
1256                 case AUDIT_LOGINUID:
1257                         result = audit_comparator(audit_get_loginuid(current),
1258                                                   f->op, f->val);
1259                         break;
1260                 case AUDIT_SUBJ_USER:
1261                 case AUDIT_SUBJ_ROLE:
1262                 case AUDIT_SUBJ_TYPE:
1263                 case AUDIT_SUBJ_SEN:
1264                 case AUDIT_SUBJ_CLR:
1265                         if (f->lsm_rule) {
1266                                 security_task_getsecid(current, &sid);
1267                                 result = security_audit_rule_match(sid,
1268                                                                    f->type,
1269                                                                    f->op,
1270                                                                    f->lsm_rule,
1271                                                                    NULL);
1272                         }
1273                         break;
1274                 }
1275
1276                 if (!result)
1277                         return 0;
1278         }
1279         switch (rule->action) {
1280         case AUDIT_NEVER:    *state = AUDIT_DISABLED;       break;
1281         case AUDIT_ALWAYS:   *state = AUDIT_RECORD_CONTEXT; break;
1282         }
1283         return 1;
1284 }
1285
1286 int audit_filter_user(struct netlink_skb_parms *cb)
1287 {
1288         enum audit_state state = AUDIT_DISABLED;
1289         struct audit_entry *e;
1290         int ret = 1;
1291
1292         rcu_read_lock();
1293         list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) {
1294                 if (audit_filter_user_rules(cb, &e->rule, &state)) {
1295                         if (state == AUDIT_DISABLED)
1296                                 ret = 0;
1297                         break;
1298                 }
1299         }
1300         rcu_read_unlock();
1301
1302         return ret; /* Audit by default */
1303 }
1304
1305 int audit_filter_type(int type)
1306 {
1307         struct audit_entry *e;
1308         int result = 0;
1309
1310         rcu_read_lock();
1311         if (list_empty(&audit_filter_list[AUDIT_FILTER_TYPE]))
1312                 goto unlock_and_return;
1313
1314         list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE],
1315                                 list) {
1316                 int i;
1317                 for (i = 0; i < e->rule.field_count; i++) {
1318                         struct audit_field *f = &e->rule.fields[i];
1319                         if (f->type == AUDIT_MSGTYPE) {
1320                                 result = audit_comparator(type, f->op, f->val);
1321                                 if (!result)
1322                                         break;
1323                         }
1324                 }
1325                 if (result)
1326                         goto unlock_and_return;
1327         }
1328 unlock_and_return:
1329         rcu_read_unlock();
1330         return result;
1331 }
1332
1333 static int update_lsm_rule(struct audit_krule *r)
1334 {
1335         struct audit_entry *entry = container_of(r, struct audit_entry, rule);
1336         struct audit_entry *nentry;
1337         int err = 0;
1338
1339         if (!security_audit_rule_known(r))
1340                 return 0;
1341
1342         nentry = audit_dupe_rule(r);
1343         if (IS_ERR(nentry)) {
1344                 /* save the first error encountered for the
1345                  * return value */
1346                 err = PTR_ERR(nentry);
1347                 audit_panic("error updating LSM filters");
1348                 if (r->watch)
1349                         list_del(&r->rlist);
1350                 list_del_rcu(&entry->list);
1351                 list_del(&r->list);
1352         } else {
1353                 if (r->watch || r->tree)
1354                         list_replace_init(&r->rlist, &nentry->rule.rlist);
1355                 list_replace_rcu(&entry->list, &nentry->list);
1356                 list_replace(&r->list, &nentry->rule.list);
1357         }
1358         call_rcu(&entry->rcu, audit_free_rule_rcu);
1359
1360         return err;
1361 }
1362
1363 /* This function will re-initialize the lsm_rule field of all applicable rules.
1364  * It will traverse the filter lists serarching for rules that contain LSM
1365  * specific filter fields.  When such a rule is found, it is copied, the
1366  * LSM field is re-initialized, and the old rule is replaced with the
1367  * updated rule. */
1368 int audit_update_lsm_rules(void)
1369 {
1370         struct audit_krule *r, *n;
1371         int i, err = 0;
1372
1373         /* audit_filter_mutex synchronizes the writers */
1374         mutex_lock(&audit_filter_mutex);
1375
1376         for (i = 0; i < AUDIT_NR_FILTERS; i++) {
1377                 list_for_each_entry_safe(r, n, &audit_rules_list[i], list) {
1378                         int res = update_lsm_rule(r);
1379                         if (!err)
1380                                 err = res;
1381                 }
1382         }
1383         mutex_unlock(&audit_filter_mutex);
1384
1385         return err;
1386 }