903caa269b5c5172d4df23bc559ac7152ff5a9d2
[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                         break;
465                 case AUDIT_ARCH:
466                         entry->rule.arch_f = f;
467                         break;
468                 case AUDIT_SUBJ_USER:
469                 case AUDIT_SUBJ_ROLE:
470                 case AUDIT_SUBJ_TYPE:
471                 case AUDIT_SUBJ_SEN:
472                 case AUDIT_SUBJ_CLR:
473                 case AUDIT_OBJ_USER:
474                 case AUDIT_OBJ_ROLE:
475                 case AUDIT_OBJ_TYPE:
476                 case AUDIT_OBJ_LEV_LOW:
477                 case AUDIT_OBJ_LEV_HIGH:
478                         str = audit_unpack_string(&bufp, &remain, f->val);
479                         if (IS_ERR(str))
480                                 goto exit_free;
481                         entry->rule.buflen += f->val;
482
483                         err = security_audit_rule_init(f->type, f->op, str,
484                                                        (void **)&f->lsm_rule);
485                         /* Keep currently invalid fields around in case they
486                          * become valid after a policy reload. */
487                         if (err == -EINVAL) {
488                                 printk(KERN_WARNING "audit rule for LSM "
489                                        "\'%s\' is invalid\n",  str);
490                                 err = 0;
491                         }
492                         if (err) {
493                                 kfree(str);
494                                 goto exit_free;
495                         } else
496                                 f->lsm_str = str;
497                         break;
498                 case AUDIT_WATCH:
499                         str = audit_unpack_string(&bufp, &remain, f->val);
500                         if (IS_ERR(str))
501                                 goto exit_free;
502                         entry->rule.buflen += f->val;
503
504                         err = audit_to_watch(&entry->rule, str, f->val, f->op);
505                         if (err) {
506                                 kfree(str);
507                                 goto exit_free;
508                         }
509                         break;
510                 case AUDIT_DIR:
511                         str = audit_unpack_string(&bufp, &remain, f->val);
512                         if (IS_ERR(str))
513                                 goto exit_free;
514                         entry->rule.buflen += f->val;
515
516                         err = audit_make_tree(&entry->rule, str, f->op);
517                         kfree(str);
518                         if (err)
519                                 goto exit_free;
520                         break;
521                 case AUDIT_INODE:
522                         err = audit_to_inode(&entry->rule, f);
523                         if (err)
524                                 goto exit_free;
525                         break;
526                 case AUDIT_FILTERKEY:
527                         err = -EINVAL;
528                         if (entry->rule.filterkey || f->val > AUDIT_MAX_KEY_LEN)
529                                 goto exit_free;
530                         str = audit_unpack_string(&bufp, &remain, f->val);
531                         if (IS_ERR(str))
532                                 goto exit_free;
533                         entry->rule.buflen += f->val;
534                         entry->rule.filterkey = str;
535                         break;
536                 case AUDIT_PERM:
537                         if (f->val & ~15)
538                                 goto exit_free;
539                         break;
540                 case AUDIT_FILETYPE:
541                         if (f->val & ~S_IFMT)
542                                 goto exit_free;
543                         break;
544                 default:
545                         goto exit_free;
546                 }
547         }
548
549         if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal)
550                 entry->rule.inode_f = NULL;
551
552 exit_nofree:
553         return entry;
554
555 exit_free:
556         audit_free_rule(entry);
557         return ERR_PTR(err);
558 }
559
560 /* Pack a filter field's string representation into data block. */
561 static inline size_t audit_pack_string(void **bufp, const char *str)
562 {
563         size_t len = strlen(str);
564
565         memcpy(*bufp, str, len);
566         *bufp += len;
567
568         return len;
569 }
570
571 /* Translate kernel rule respresentation to struct audit_rule.
572  * Exists for backward compatibility with userspace. */
573 static struct audit_rule *audit_krule_to_rule(struct audit_krule *krule)
574 {
575         struct audit_rule *rule;
576         int i;
577
578         rule = kzalloc(sizeof(*rule), GFP_KERNEL);
579         if (unlikely(!rule))
580                 return NULL;
581
582         rule->flags = krule->flags | krule->listnr;
583         rule->action = krule->action;
584         rule->field_count = krule->field_count;
585         for (i = 0; i < rule->field_count; i++) {
586                 rule->values[i] = krule->fields[i].val;
587                 rule->fields[i] = krule->fields[i].type;
588
589                 if (krule->vers_ops == 1) {
590                         if (krule->fields[i].op == Audit_not_equal)
591                                 rule->fields[i] |= AUDIT_NEGATE;
592                 } else {
593                         rule->fields[i] |= audit_ops[krule->fields[i].op];
594                 }
595         }
596         for (i = 0; i < AUDIT_BITMASK_SIZE; i++) rule->mask[i] = krule->mask[i];
597
598         return rule;
599 }
600
601 /* Translate kernel rule respresentation to struct audit_rule_data. */
602 static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule)
603 {
604         struct audit_rule_data *data;
605         void *bufp;
606         int i;
607
608         data = kmalloc(sizeof(*data) + krule->buflen, GFP_KERNEL);
609         if (unlikely(!data))
610                 return NULL;
611         memset(data, 0, sizeof(*data));
612
613         data->flags = krule->flags | krule->listnr;
614         data->action = krule->action;
615         data->field_count = krule->field_count;
616         bufp = data->buf;
617         for (i = 0; i < data->field_count; i++) {
618                 struct audit_field *f = &krule->fields[i];
619
620                 data->fields[i] = f->type;
621                 data->fieldflags[i] = audit_ops[f->op];
622                 switch(f->type) {
623                 case AUDIT_SUBJ_USER:
624                 case AUDIT_SUBJ_ROLE:
625                 case AUDIT_SUBJ_TYPE:
626                 case AUDIT_SUBJ_SEN:
627                 case AUDIT_SUBJ_CLR:
628                 case AUDIT_OBJ_USER:
629                 case AUDIT_OBJ_ROLE:
630                 case AUDIT_OBJ_TYPE:
631                 case AUDIT_OBJ_LEV_LOW:
632                 case AUDIT_OBJ_LEV_HIGH:
633                         data->buflen += data->values[i] =
634                                 audit_pack_string(&bufp, f->lsm_str);
635                         break;
636                 case AUDIT_WATCH:
637                         data->buflen += data->values[i] =
638                                 audit_pack_string(&bufp,
639                                                   audit_watch_path(krule->watch));
640                         break;
641                 case AUDIT_DIR:
642                         data->buflen += data->values[i] =
643                                 audit_pack_string(&bufp,
644                                                   audit_tree_path(krule->tree));
645                         break;
646                 case AUDIT_FILTERKEY:
647                         data->buflen += data->values[i] =
648                                 audit_pack_string(&bufp, krule->filterkey);
649                         break;
650                 default:
651                         data->values[i] = f->val;
652                 }
653         }
654         for (i = 0; i < AUDIT_BITMASK_SIZE; i++) data->mask[i] = krule->mask[i];
655
656         return data;
657 }
658
659 /* Compare two rules in kernel format.  Considered success if rules
660  * don't match. */
661 static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b)
662 {
663         int i;
664
665         if (a->flags != b->flags ||
666             a->listnr != b->listnr ||
667             a->action != b->action ||
668             a->field_count != b->field_count)
669                 return 1;
670
671         for (i = 0; i < a->field_count; i++) {
672                 if (a->fields[i].type != b->fields[i].type ||
673                     a->fields[i].op != b->fields[i].op)
674                         return 1;
675
676                 switch(a->fields[i].type) {
677                 case AUDIT_SUBJ_USER:
678                 case AUDIT_SUBJ_ROLE:
679                 case AUDIT_SUBJ_TYPE:
680                 case AUDIT_SUBJ_SEN:
681                 case AUDIT_SUBJ_CLR:
682                 case AUDIT_OBJ_USER:
683                 case AUDIT_OBJ_ROLE:
684                 case AUDIT_OBJ_TYPE:
685                 case AUDIT_OBJ_LEV_LOW:
686                 case AUDIT_OBJ_LEV_HIGH:
687                         if (strcmp(a->fields[i].lsm_str, b->fields[i].lsm_str))
688                                 return 1;
689                         break;
690                 case AUDIT_WATCH:
691                         if (strcmp(audit_watch_path(a->watch),
692                                    audit_watch_path(b->watch)))
693                                 return 1;
694                         break;
695                 case AUDIT_DIR:
696                         if (strcmp(audit_tree_path(a->tree),
697                                    audit_tree_path(b->tree)))
698                                 return 1;
699                         break;
700                 case AUDIT_FILTERKEY:
701                         /* both filterkeys exist based on above type compare */
702                         if (strcmp(a->filterkey, b->filterkey))
703                                 return 1;
704                         break;
705                 default:
706                         if (a->fields[i].val != b->fields[i].val)
707                                 return 1;
708                 }
709         }
710
711         for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
712                 if (a->mask[i] != b->mask[i])
713                         return 1;
714
715         return 0;
716 }
717
718 /* Duplicate LSM field information.  The lsm_rule is opaque, so must be
719  * re-initialized. */
720 static inline int audit_dupe_lsm_field(struct audit_field *df,
721                                            struct audit_field *sf)
722 {
723         int ret = 0;
724         char *lsm_str;
725
726         /* our own copy of lsm_str */
727         lsm_str = kstrdup(sf->lsm_str, GFP_KERNEL);
728         if (unlikely(!lsm_str))
729                 return -ENOMEM;
730         df->lsm_str = lsm_str;
731
732         /* our own (refreshed) copy of lsm_rule */
733         ret = security_audit_rule_init(df->type, df->op, df->lsm_str,
734                                        (void **)&df->lsm_rule);
735         /* Keep currently invalid fields around in case they
736          * become valid after a policy reload. */
737         if (ret == -EINVAL) {
738                 printk(KERN_WARNING "audit rule for LSM \'%s\' is "
739                        "invalid\n", df->lsm_str);
740                 ret = 0;
741         }
742
743         return ret;
744 }
745
746 /* Duplicate an audit rule.  This will be a deep copy with the exception
747  * of the watch - that pointer is carried over.  The LSM specific fields
748  * will be updated in the copy.  The point is to be able to replace the old
749  * rule with the new rule in the filterlist, then free the old rule.
750  * The rlist element is undefined; list manipulations are handled apart from
751  * the initial copy. */
752 struct audit_entry *audit_dupe_rule(struct audit_krule *old)
753 {
754         u32 fcount = old->field_count;
755         struct audit_entry *entry;
756         struct audit_krule *new;
757         char *fk;
758         int i, err = 0;
759
760         entry = audit_init_entry(fcount);
761         if (unlikely(!entry))
762                 return ERR_PTR(-ENOMEM);
763
764         new = &entry->rule;
765         new->vers_ops = old->vers_ops;
766         new->flags = old->flags;
767         new->listnr = old->listnr;
768         new->action = old->action;
769         for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
770                 new->mask[i] = old->mask[i];
771         new->prio = old->prio;
772         new->buflen = old->buflen;
773         new->inode_f = old->inode_f;
774         new->field_count = old->field_count;
775
776         /*
777          * note that we are OK with not refcounting here; audit_match_tree()
778          * never dereferences tree and we can't get false positives there
779          * since we'd have to have rule gone from the list *and* removed
780          * before the chunks found by lookup had been allocated, i.e. before
781          * the beginning of list scan.
782          */
783         new->tree = old->tree;
784         memcpy(new->fields, old->fields, sizeof(struct audit_field) * fcount);
785
786         /* deep copy this information, updating the lsm_rule fields, because
787          * the originals will all be freed when the old rule is freed. */
788         for (i = 0; i < fcount; i++) {
789                 switch (new->fields[i].type) {
790                 case AUDIT_SUBJ_USER:
791                 case AUDIT_SUBJ_ROLE:
792                 case AUDIT_SUBJ_TYPE:
793                 case AUDIT_SUBJ_SEN:
794                 case AUDIT_SUBJ_CLR:
795                 case AUDIT_OBJ_USER:
796                 case AUDIT_OBJ_ROLE:
797                 case AUDIT_OBJ_TYPE:
798                 case AUDIT_OBJ_LEV_LOW:
799                 case AUDIT_OBJ_LEV_HIGH:
800                         err = audit_dupe_lsm_field(&new->fields[i],
801                                                        &old->fields[i]);
802                         break;
803                 case AUDIT_FILTERKEY:
804                         fk = kstrdup(old->filterkey, GFP_KERNEL);
805                         if (unlikely(!fk))
806                                 err = -ENOMEM;
807                         else
808                                 new->filterkey = fk;
809                 }
810                 if (err) {
811                         audit_free_rule(entry);
812                         return ERR_PTR(err);
813                 }
814         }
815
816         if (old->watch) {
817                 audit_get_watch(old->watch);
818                 new->watch = old->watch;
819         }
820
821         return entry;
822 }
823
824 /* Find an existing audit rule.
825  * Caller must hold audit_filter_mutex to prevent stale rule data. */
826 static struct audit_entry *audit_find_rule(struct audit_entry *entry,
827                                            struct list_head **p)
828 {
829         struct audit_entry *e, *found = NULL;
830         struct list_head *list;
831         int h;
832
833         if (entry->rule.inode_f) {
834                 h = audit_hash_ino(entry->rule.inode_f->val);
835                 *p = list = &audit_inode_hash[h];
836         } else if (entry->rule.watch) {
837                 /* we don't know the inode number, so must walk entire hash */
838                 for (h = 0; h < AUDIT_INODE_BUCKETS; h++) {
839                         list = &audit_inode_hash[h];
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                 }
846                 goto out;
847         } else {
848                 *p = list = &audit_filter_list[entry->rule.listnr];
849         }
850
851         list_for_each_entry(e, list, list)
852                 if (!audit_compare_rule(&entry->rule, &e->rule)) {
853                         found = e;
854                         goto out;
855                 }
856
857 out:
858         return found;
859 }
860
861 static u64 prio_low = ~0ULL/2;
862 static u64 prio_high = ~0ULL/2 - 1;
863
864 /* Add rule to given filterlist if not a duplicate. */
865 static inline int audit_add_rule(struct audit_entry *entry)
866 {
867         struct audit_entry *e;
868         struct audit_watch *watch = entry->rule.watch;
869         struct audit_tree *tree = entry->rule.tree;
870         struct list_head *list;
871         int err;
872 #ifdef CONFIG_AUDITSYSCALL
873         int dont_count = 0;
874
875         /* If either of these, don't count towards total */
876         if (entry->rule.listnr == AUDIT_FILTER_USER ||
877                 entry->rule.listnr == AUDIT_FILTER_TYPE)
878                 dont_count = 1;
879 #endif
880
881         mutex_lock(&audit_filter_mutex);
882         e = audit_find_rule(entry, &list);
883         if (e) {
884                 mutex_unlock(&audit_filter_mutex);
885                 err = -EEXIST;
886                 /* normally audit_add_tree_rule() will free it on failure */
887                 if (tree)
888                         audit_put_tree(tree);
889                 goto error;
890         }
891
892         if (watch) {
893                 /* audit_filter_mutex is dropped and re-taken during this call */
894                 err = audit_add_watch(&entry->rule, &list);
895                 if (err) {
896                         mutex_unlock(&audit_filter_mutex);
897                         goto error;
898                 }
899         }
900         if (tree) {
901                 err = audit_add_tree_rule(&entry->rule);
902                 if (err) {
903                         mutex_unlock(&audit_filter_mutex);
904                         goto error;
905                 }
906         }
907
908         entry->rule.prio = ~0ULL;
909         if (entry->rule.listnr == AUDIT_FILTER_EXIT) {
910                 if (entry->rule.flags & AUDIT_FILTER_PREPEND)
911                         entry->rule.prio = ++prio_high;
912                 else
913                         entry->rule.prio = --prio_low;
914         }
915
916         if (entry->rule.flags & AUDIT_FILTER_PREPEND) {
917                 list_add(&entry->rule.list,
918                          &audit_rules_list[entry->rule.listnr]);
919                 list_add_rcu(&entry->list, list);
920                 entry->rule.flags &= ~AUDIT_FILTER_PREPEND;
921         } else {
922                 list_add_tail(&entry->rule.list,
923                               &audit_rules_list[entry->rule.listnr]);
924                 list_add_tail_rcu(&entry->list, list);
925         }
926 #ifdef CONFIG_AUDITSYSCALL
927         if (!dont_count)
928                 audit_n_rules++;
929
930         if (!audit_match_signal(entry))
931                 audit_signals++;
932 #endif
933         mutex_unlock(&audit_filter_mutex);
934
935         return 0;
936
937 error:
938         if (watch)
939                 audit_put_watch(watch); /* tmp watch, matches initial get */
940         return err;
941 }
942
943 /* Remove an existing rule from filterlist. */
944 static inline int audit_del_rule(struct audit_entry *entry)
945 {
946         struct audit_entry  *e;
947         struct audit_watch *watch = entry->rule.watch;
948         struct audit_tree *tree = entry->rule.tree;
949         struct list_head *list;
950         int ret = 0;
951 #ifdef CONFIG_AUDITSYSCALL
952         int dont_count = 0;
953
954         /* If either of these, don't count towards total */
955         if (entry->rule.listnr == AUDIT_FILTER_USER ||
956                 entry->rule.listnr == AUDIT_FILTER_TYPE)
957                 dont_count = 1;
958 #endif
959
960         mutex_lock(&audit_filter_mutex);
961         e = audit_find_rule(entry, &list);
962         if (!e) {
963                 mutex_unlock(&audit_filter_mutex);
964                 ret = -ENOENT;
965                 goto out;
966         }
967
968         if (e->rule.watch)
969                 audit_remove_watch_rule(&e->rule);
970
971         if (e->rule.tree)
972                 audit_remove_tree_rule(&e->rule);
973
974         list_del_rcu(&e->list);
975         list_del(&e->rule.list);
976         call_rcu(&e->rcu, audit_free_rule_rcu);
977
978 #ifdef CONFIG_AUDITSYSCALL
979         if (!dont_count)
980                 audit_n_rules--;
981
982         if (!audit_match_signal(entry))
983                 audit_signals--;
984 #endif
985         mutex_unlock(&audit_filter_mutex);
986
987 out:
988         if (watch)
989                 audit_put_watch(watch); /* match initial get */
990         if (tree)
991                 audit_put_tree(tree);   /* that's the temporary one */
992
993         return ret;
994 }
995
996 /* List rules using struct audit_rule.  Exists for backward
997  * compatibility with userspace. */
998 static void audit_list(int pid, int seq, struct sk_buff_head *q)
999 {
1000         struct sk_buff *skb;
1001         struct audit_krule *r;
1002         int i;
1003
1004         /* This is a blocking read, so use audit_filter_mutex instead of rcu
1005          * iterator to sync with list writers. */
1006         for (i=0; i<AUDIT_NR_FILTERS; i++) {
1007                 list_for_each_entry(r, &audit_rules_list[i], list) {
1008                         struct audit_rule *rule;
1009
1010                         rule = audit_krule_to_rule(r);
1011                         if (unlikely(!rule))
1012                                 break;
1013                         skb = audit_make_reply(pid, seq, AUDIT_LIST, 0, 1,
1014                                          rule, sizeof(*rule));
1015                         if (skb)
1016                                 skb_queue_tail(q, skb);
1017                         kfree(rule);
1018                 }
1019         }
1020         skb = audit_make_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0);
1021         if (skb)
1022                 skb_queue_tail(q, skb);
1023 }
1024
1025 /* List rules using struct audit_rule_data. */
1026 static void audit_list_rules(int pid, int seq, struct sk_buff_head *q)
1027 {
1028         struct sk_buff *skb;
1029         struct audit_krule *r;
1030         int i;
1031
1032         /* This is a blocking read, so use audit_filter_mutex instead of rcu
1033          * iterator to sync with list writers. */
1034         for (i=0; i<AUDIT_NR_FILTERS; i++) {
1035                 list_for_each_entry(r, &audit_rules_list[i], list) {
1036                         struct audit_rule_data *data;
1037
1038                         data = audit_krule_to_data(r);
1039                         if (unlikely(!data))
1040                                 break;
1041                         skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 0, 1,
1042                                          data, sizeof(*data) + data->buflen);
1043                         if (skb)
1044                                 skb_queue_tail(q, skb);
1045                         kfree(data);
1046                 }
1047         }
1048         skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0);
1049         if (skb)
1050                 skb_queue_tail(q, skb);
1051 }
1052
1053 /* Log rule additions and removals */
1054 static void audit_log_rule_change(uid_t loginuid, u32 sessionid, u32 sid,
1055                                   char *action, struct audit_krule *rule,
1056                                   int res)
1057 {
1058         struct audit_buffer *ab;
1059
1060         if (!audit_enabled)
1061                 return;
1062
1063         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
1064         if (!ab)
1065                 return;
1066         audit_log_format(ab, "auid=%u ses=%u", loginuid, sessionid);
1067         if (sid) {
1068                 char *ctx = NULL;
1069                 u32 len;
1070                 if (security_secid_to_secctx(sid, &ctx, &len))
1071                         audit_log_format(ab, " ssid=%u", sid);
1072                 else {
1073                         audit_log_format(ab, " subj=%s", ctx);
1074                         security_release_secctx(ctx, len);
1075                 }
1076         }
1077         audit_log_format(ab, " op=");
1078         audit_log_string(ab, action);
1079         audit_log_key(ab, rule->filterkey);
1080         audit_log_format(ab, " list=%d res=%d", rule->listnr, res);
1081         audit_log_end(ab);
1082 }
1083
1084 /**
1085  * audit_receive_filter - apply all rules to the specified message type
1086  * @type: audit message type
1087  * @pid: target pid for netlink audit messages
1088  * @uid: target uid for netlink audit messages
1089  * @seq: netlink audit message sequence (serial) number
1090  * @data: payload data
1091  * @datasz: size of payload data
1092  * @loginuid: loginuid of sender
1093  * @sessionid: sessionid for netlink audit message
1094  * @sid: SE Linux Security ID of sender
1095  */
1096 int audit_receive_filter(int type, int pid, int uid, int seq, void *data,
1097                          size_t datasz, uid_t loginuid, u32 sessionid, u32 sid)
1098 {
1099         struct task_struct *tsk;
1100         struct audit_netlink_list *dest;
1101         int err = 0;
1102         struct audit_entry *entry;
1103
1104         switch (type) {
1105         case AUDIT_LIST:
1106         case AUDIT_LIST_RULES:
1107                 /* We can't just spew out the rules here because we might fill
1108                  * the available socket buffer space and deadlock waiting for
1109                  * auditctl to read from it... which isn't ever going to
1110                  * happen if we're actually running in the context of auditctl
1111                  * trying to _send_ the stuff */
1112
1113                 dest = kmalloc(sizeof(struct audit_netlink_list), GFP_KERNEL);
1114                 if (!dest)
1115                         return -ENOMEM;
1116                 dest->pid = pid;
1117                 skb_queue_head_init(&dest->q);
1118
1119                 mutex_lock(&audit_filter_mutex);
1120                 if (type == AUDIT_LIST)
1121                         audit_list(pid, seq, &dest->q);
1122                 else
1123                         audit_list_rules(pid, seq, &dest->q);
1124                 mutex_unlock(&audit_filter_mutex);
1125
1126                 tsk = kthread_run(audit_send_list, dest, "audit_send_list");
1127                 if (IS_ERR(tsk)) {
1128                         skb_queue_purge(&dest->q);
1129                         kfree(dest);
1130                         err = PTR_ERR(tsk);
1131                 }
1132                 break;
1133         case AUDIT_ADD:
1134         case AUDIT_ADD_RULE:
1135                 if (type == AUDIT_ADD)
1136                         entry = audit_rule_to_entry(data);
1137                 else
1138                         entry = audit_data_to_entry(data, datasz);
1139                 if (IS_ERR(entry))
1140                         return PTR_ERR(entry);
1141
1142                 err = audit_add_rule(entry);
1143                 audit_log_rule_change(loginuid, sessionid, sid, "add rule",
1144                                       &entry->rule, !err);
1145
1146                 if (err)
1147                         audit_free_rule(entry);
1148                 break;
1149         case AUDIT_DEL:
1150         case AUDIT_DEL_RULE:
1151                 if (type == AUDIT_DEL)
1152                         entry = audit_rule_to_entry(data);
1153                 else
1154                         entry = audit_data_to_entry(data, datasz);
1155                 if (IS_ERR(entry))
1156                         return PTR_ERR(entry);
1157
1158                 err = audit_del_rule(entry);
1159                 audit_log_rule_change(loginuid, sessionid, sid, "remove rule",
1160                                       &entry->rule, !err);
1161
1162                 audit_free_rule(entry);
1163                 break;
1164         default:
1165                 return -EINVAL;
1166         }
1167
1168         return err;
1169 }
1170
1171 int audit_comparator(u32 left, u32 op, u32 right)
1172 {
1173         switch (op) {
1174         case Audit_equal:
1175                 return (left == right);
1176         case Audit_not_equal:
1177                 return (left != right);
1178         case Audit_lt:
1179                 return (left < right);
1180         case Audit_le:
1181                 return (left <= right);
1182         case Audit_gt:
1183                 return (left > right);
1184         case Audit_ge:
1185                 return (left >= right);
1186         case Audit_bitmask:
1187                 return (left & right);
1188         case Audit_bittest:
1189                 return ((left & right) == right);
1190         default:
1191                 BUG();
1192                 return 0;
1193         }
1194 }
1195
1196 /* Compare given dentry name with last component in given path,
1197  * return of 0 indicates a match. */
1198 int audit_compare_dname_path(const char *dname, const char *path,
1199                              int *dirlen)
1200 {
1201         int dlen, plen;
1202         const char *p;
1203
1204         if (!dname || !path)
1205                 return 1;
1206
1207         dlen = strlen(dname);
1208         plen = strlen(path);
1209         if (plen < dlen)
1210                 return 1;
1211
1212         /* disregard trailing slashes */
1213         p = path + plen - 1;
1214         while ((*p == '/') && (p > path))
1215                 p--;
1216
1217         /* find last path component */
1218         p = p - dlen + 1;
1219         if (p < path)
1220                 return 1;
1221         else if (p > path) {
1222                 if (*--p != '/')
1223                         return 1;
1224                 else
1225                         p++;
1226         }
1227
1228         /* return length of path's directory component */
1229         if (dirlen)
1230                 *dirlen = p - path;
1231         return strncmp(p, dname, dlen);
1232 }
1233
1234 static int audit_filter_user_rules(struct netlink_skb_parms *cb,
1235                                    struct audit_krule *rule,
1236                                    enum audit_state *state)
1237 {
1238         int i;
1239
1240         for (i = 0; i < rule->field_count; i++) {
1241                 struct audit_field *f = &rule->fields[i];
1242                 int result = 0;
1243                 u32 sid;
1244
1245                 switch (f->type) {
1246                 case AUDIT_PID:
1247                         result = audit_comparator(cb->creds.pid, f->op, f->val);
1248                         break;
1249                 case AUDIT_UID:
1250                         result = audit_comparator(cb->creds.uid, f->op, f->val);
1251                         break;
1252                 case AUDIT_GID:
1253                         result = audit_comparator(cb->creds.gid, f->op, f->val);
1254                         break;
1255                 case AUDIT_LOGINUID:
1256                         result = audit_comparator(audit_get_loginuid(current),
1257                                                   f->op, f->val);
1258                         break;
1259                 case AUDIT_SUBJ_USER:
1260                 case AUDIT_SUBJ_ROLE:
1261                 case AUDIT_SUBJ_TYPE:
1262                 case AUDIT_SUBJ_SEN:
1263                 case AUDIT_SUBJ_CLR:
1264                         if (f->lsm_rule) {
1265                                 security_task_getsecid(current, &sid);
1266                                 result = security_audit_rule_match(sid,
1267                                                                    f->type,
1268                                                                    f->op,
1269                                                                    f->lsm_rule,
1270                                                                    NULL);
1271                         }
1272                         break;
1273                 }
1274
1275                 if (!result)
1276                         return 0;
1277         }
1278         switch (rule->action) {
1279         case AUDIT_NEVER:    *state = AUDIT_DISABLED;       break;
1280         case AUDIT_ALWAYS:   *state = AUDIT_RECORD_CONTEXT; break;
1281         }
1282         return 1;
1283 }
1284
1285 int audit_filter_user(struct netlink_skb_parms *cb)
1286 {
1287         enum audit_state state = AUDIT_DISABLED;
1288         struct audit_entry *e;
1289         int ret = 1;
1290
1291         rcu_read_lock();
1292         list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) {
1293                 if (audit_filter_user_rules(cb, &e->rule, &state)) {
1294                         if (state == AUDIT_DISABLED)
1295                                 ret = 0;
1296                         break;
1297                 }
1298         }
1299         rcu_read_unlock();
1300
1301         return ret; /* Audit by default */
1302 }
1303
1304 int audit_filter_type(int type)
1305 {
1306         struct audit_entry *e;
1307         int result = 0;
1308
1309         rcu_read_lock();
1310         if (list_empty(&audit_filter_list[AUDIT_FILTER_TYPE]))
1311                 goto unlock_and_return;
1312
1313         list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE],
1314                                 list) {
1315                 int i;
1316                 for (i = 0; i < e->rule.field_count; i++) {
1317                         struct audit_field *f = &e->rule.fields[i];
1318                         if (f->type == AUDIT_MSGTYPE) {
1319                                 result = audit_comparator(type, f->op, f->val);
1320                                 if (!result)
1321                                         break;
1322                         }
1323                 }
1324                 if (result)
1325                         goto unlock_and_return;
1326         }
1327 unlock_and_return:
1328         rcu_read_unlock();
1329         return result;
1330 }
1331
1332 static int update_lsm_rule(struct audit_krule *r)
1333 {
1334         struct audit_entry *entry = container_of(r, struct audit_entry, rule);
1335         struct audit_entry *nentry;
1336         int err = 0;
1337
1338         if (!security_audit_rule_known(r))
1339                 return 0;
1340
1341         nentry = audit_dupe_rule(r);
1342         if (IS_ERR(nentry)) {
1343                 /* save the first error encountered for the
1344                  * return value */
1345                 err = PTR_ERR(nentry);
1346                 audit_panic("error updating LSM filters");
1347                 if (r->watch)
1348                         list_del(&r->rlist);
1349                 list_del_rcu(&entry->list);
1350                 list_del(&r->list);
1351         } else {
1352                 if (r->watch || r->tree)
1353                         list_replace_init(&r->rlist, &nentry->rule.rlist);
1354                 list_replace_rcu(&entry->list, &nentry->list);
1355                 list_replace(&r->list, &nentry->rule.list);
1356         }
1357         call_rcu(&entry->rcu, audit_free_rule_rcu);
1358
1359         return err;
1360 }
1361
1362 /* This function will re-initialize the lsm_rule field of all applicable rules.
1363  * It will traverse the filter lists serarching for rules that contain LSM
1364  * specific filter fields.  When such a rule is found, it is copied, the
1365  * LSM field is re-initialized, and the old rule is replaced with the
1366  * updated rule. */
1367 int audit_update_lsm_rules(void)
1368 {
1369         struct audit_krule *r, *n;
1370         int i, err = 0;
1371
1372         /* audit_filter_mutex synchronizes the writers */
1373         mutex_lock(&audit_filter_mutex);
1374
1375         for (i = 0; i < AUDIT_NR_FILTERS; i++) {
1376                 list_for_each_entry_safe(r, n, &audit_rules_list[i], list) {
1377                         int res = update_lsm_rule(r);
1378                         if (!err)
1379                                 err = res;
1380                 }
1381         }
1382         mutex_unlock(&audit_filter_mutex);
1383
1384         return err;
1385 }