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Linux/security/integrity/ima/ima_policy.c

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  1 /*
  2  * Copyright (C) 2008 IBM Corporation
  3  * Author: Mimi Zohar <zohar@us.ibm.com>
  4  *
  5  * This program is free software; you can redistribute it and/or modify
  6  * it under the terms of the GNU General Public License as published by
  7  * the Free Software Foundation, version 2 of the License.
  8  *
  9  * ima_policy.c
 10  *      - initialize default measure policy rules
 11  *
 12  */
 13 #include <linux/module.h>
 14 #include <linux/list.h>
 15 #include <linux/security.h>
 16 #include <linux/magic.h>
 17 #include <linux/parser.h>
 18 #include <linux/slab.h>
 19 #include <linux/genhd.h>
 20 
 21 #include "ima.h"
 22 
 23 /* flags definitions */
 24 #define IMA_FUNC        0x0001
 25 #define IMA_MASK        0x0002
 26 #define IMA_FSMAGIC     0x0004
 27 #define IMA_UID         0x0008
 28 #define IMA_FOWNER      0x0010
 29 #define IMA_FSUUID      0x0020
 30 #define IMA_INMASK      0x0040
 31 #define IMA_EUID        0x0080
 32 
 33 #define UNKNOWN         0
 34 #define MEASURE         0x0001  /* same as IMA_MEASURE */
 35 #define DONT_MEASURE    0x0002
 36 #define APPRAISE        0x0004  /* same as IMA_APPRAISE */
 37 #define DONT_APPRAISE   0x0008
 38 #define AUDIT           0x0040
 39 
 40 #define MAX_LSM_RULES 6
 41 enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
 42         LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
 43 };
 44 
 45 struct ima_rule_entry {
 46         struct list_head list;
 47         int action;
 48         unsigned int flags;
 49         enum ima_hooks func;
 50         int mask;
 51         unsigned long fsmagic;
 52         u8 fsuuid[16];
 53         kuid_t uid;
 54         kuid_t fowner;
 55         struct {
 56                 void *rule;     /* LSM file metadata specific */
 57                 void *args_p;   /* audit value */
 58                 int type;       /* audit type */
 59         } lsm[MAX_LSM_RULES];
 60 };
 61 
 62 /*
 63  * Without LSM specific knowledge, the default policy can only be
 64  * written in terms of .action, .func, .mask, .fsmagic, .uid, and .fowner
 65  */
 66 
 67 /*
 68  * The minimum rule set to allow for full TCB coverage.  Measures all files
 69  * opened or mmap for exec and everything read by root.  Dangerous because
 70  * normal users can easily run the machine out of memory simply building
 71  * and running executables.
 72  */
 73 static struct ima_rule_entry default_rules[] = {
 74         {.action = DONT_MEASURE,.fsmagic = PROC_SUPER_MAGIC,.flags = IMA_FSMAGIC},
 75         {.action = DONT_MEASURE,.fsmagic = SYSFS_MAGIC,.flags = IMA_FSMAGIC},
 76         {.action = DONT_MEASURE,.fsmagic = DEBUGFS_MAGIC,.flags = IMA_FSMAGIC},
 77         {.action = DONT_MEASURE,.fsmagic = TMPFS_MAGIC,.flags = IMA_FSMAGIC},
 78         {.action = DONT_MEASURE,.fsmagic = DEVPTS_SUPER_MAGIC,.flags = IMA_FSMAGIC},
 79         {.action = DONT_MEASURE,.fsmagic = BINFMTFS_MAGIC,.flags = IMA_FSMAGIC},
 80         {.action = DONT_MEASURE,.fsmagic = SECURITYFS_MAGIC,.flags = IMA_FSMAGIC},
 81         {.action = DONT_MEASURE,.fsmagic = SELINUX_MAGIC,.flags = IMA_FSMAGIC},
 82         {.action = MEASURE,.func = MMAP_CHECK,.mask = MAY_EXEC,
 83          .flags = IMA_FUNC | IMA_MASK},
 84         {.action = MEASURE,.func = BPRM_CHECK,.mask = MAY_EXEC,
 85          .flags = IMA_FUNC | IMA_MASK},
 86         {.action = MEASURE,.func = FILE_CHECK,.mask = MAY_READ,.uid = GLOBAL_ROOT_UID,
 87          .flags = IMA_FUNC | IMA_MASK | IMA_UID},
 88         {.action = MEASURE,.func = MODULE_CHECK, .flags = IMA_FUNC},
 89 };
 90 
 91 static struct ima_rule_entry default_appraise_rules[] = {
 92         {.action = DONT_APPRAISE,.fsmagic = PROC_SUPER_MAGIC,.flags = IMA_FSMAGIC},
 93         {.action = DONT_APPRAISE,.fsmagic = SYSFS_MAGIC,.flags = IMA_FSMAGIC},
 94         {.action = DONT_APPRAISE,.fsmagic = DEBUGFS_MAGIC,.flags = IMA_FSMAGIC},
 95         {.action = DONT_APPRAISE,.fsmagic = TMPFS_MAGIC,.flags = IMA_FSMAGIC},
 96         {.action = DONT_APPRAISE,.fsmagic = RAMFS_MAGIC,.flags = IMA_FSMAGIC},
 97         {.action = DONT_APPRAISE,.fsmagic = DEVPTS_SUPER_MAGIC,.flags = IMA_FSMAGIC},
 98         {.action = DONT_APPRAISE,.fsmagic = BINFMTFS_MAGIC,.flags = IMA_FSMAGIC},
 99         {.action = DONT_APPRAISE,.fsmagic = SECURITYFS_MAGIC,.flags = IMA_FSMAGIC},
100         {.action = DONT_APPRAISE,.fsmagic = SELINUX_MAGIC,.flags = IMA_FSMAGIC},
101         {.action = DONT_APPRAISE,.fsmagic = CGROUP_SUPER_MAGIC,.flags = IMA_FSMAGIC},
102         {.action = APPRAISE,.fowner = GLOBAL_ROOT_UID,.flags = IMA_FOWNER},
103 };
104 
105 static LIST_HEAD(ima_default_rules);
106 static LIST_HEAD(ima_policy_rules);
107 static struct list_head *ima_rules;
108 
109 static DEFINE_MUTEX(ima_rules_mutex);
110 
111 static bool ima_use_tcb __initdata;
112 static int __init default_measure_policy_setup(char *str)
113 {
114         ima_use_tcb = 1;
115         return 1;
116 }
117 __setup("ima_tcb", default_measure_policy_setup);
118 
119 static bool ima_use_appraise_tcb __initdata;
120 static int __init default_appraise_policy_setup(char *str)
121 {
122         ima_use_appraise_tcb = 1;
123         return 1;
124 }
125 __setup("ima_appraise_tcb", default_appraise_policy_setup);
126 
127 /* 
128  * Although the IMA policy does not change, the LSM policy can be
129  * reloaded, leaving the IMA LSM based rules referring to the old,
130  * stale LSM policy.
131  *
132  * Update the IMA LSM based rules to reflect the reloaded LSM policy. 
133  * We assume the rules still exist; and BUG_ON() if they don't.
134  */
135 static void ima_lsm_update_rules(void)
136 {
137         struct ima_rule_entry *entry, *tmp;
138         int result;
139         int i;
140 
141         mutex_lock(&ima_rules_mutex);
142         list_for_each_entry_safe(entry, tmp, &ima_policy_rules, list) {
143                 for (i = 0; i < MAX_LSM_RULES; i++) {
144                         if (!entry->lsm[i].rule)
145                                 continue;
146                         result = security_filter_rule_init(entry->lsm[i].type,
147                                                            Audit_equal,
148                                                            entry->lsm[i].args_p,
149                                                            &entry->lsm[i].rule);
150                         BUG_ON(!entry->lsm[i].rule);
151                 }
152         }
153         mutex_unlock(&ima_rules_mutex);
154 }
155 
156 /**
157  * ima_match_rules - determine whether an inode matches the measure rule.
158  * @rule: a pointer to a rule
159  * @inode: a pointer to an inode
160  * @func: LIM hook identifier
161  * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
162  *
163  * Returns true on rule match, false on failure.
164  */
165 static bool ima_match_rules(struct ima_rule_entry *rule,
166                             struct inode *inode, enum ima_hooks func, int mask)
167 {
168         struct task_struct *tsk = current;
169         const struct cred *cred = current_cred();
170         int i;
171 
172         if ((rule->flags & IMA_FUNC) && rule->func != func)
173                 return false;
174         if ((rule->flags & IMA_MASK) && rule->mask != mask)
175                 return false;
176         if ((rule->flags & IMA_INMASK) &&
177             (!(rule->mask & mask) && func != POST_SETATTR))
178                 return false;
179         if ((rule->flags & IMA_FSMAGIC)
180             && rule->fsmagic != inode->i_sb->s_magic)
181                 return false;
182         if ((rule->flags & IMA_FSUUID) &&
183             memcmp(rule->fsuuid, inode->i_sb->s_uuid, sizeof(rule->fsuuid)))
184                 return false;
185         if ((rule->flags & IMA_UID) && !uid_eq(rule->uid, cred->uid))
186                 return false;
187         if (rule->flags & IMA_EUID) {
188                 if (has_capability_noaudit(current, CAP_SETUID)) {
189                         if (!uid_eq(rule->uid, cred->euid)
190                             && !uid_eq(rule->uid, cred->suid)
191                             && !uid_eq(rule->uid, cred->uid))
192                                 return false;
193                 } else if (!uid_eq(rule->uid, cred->euid))
194                         return false;
195         }
196 
197         if ((rule->flags & IMA_FOWNER) && !uid_eq(rule->fowner, inode->i_uid))
198                 return false;
199         for (i = 0; i < MAX_LSM_RULES; i++) {
200                 int rc = 0;
201                 u32 osid, sid;
202                 int retried = 0;
203 
204                 if (!rule->lsm[i].rule)
205                         continue;
206 retry:
207                 switch (i) {
208                 case LSM_OBJ_USER:
209                 case LSM_OBJ_ROLE:
210                 case LSM_OBJ_TYPE:
211                         security_inode_getsecid(inode, &osid);
212                         rc = security_filter_rule_match(osid,
213                                                         rule->lsm[i].type,
214                                                         Audit_equal,
215                                                         rule->lsm[i].rule,
216                                                         NULL);
217                         break;
218                 case LSM_SUBJ_USER:
219                 case LSM_SUBJ_ROLE:
220                 case LSM_SUBJ_TYPE:
221                         security_task_getsecid(tsk, &sid);
222                         rc = security_filter_rule_match(sid,
223                                                         rule->lsm[i].type,
224                                                         Audit_equal,
225                                                         rule->lsm[i].rule,
226                                                         NULL);
227                 default:
228                         break;
229                 }
230                 if ((rc < 0) && (!retried)) {
231                         retried = 1;
232                         ima_lsm_update_rules();
233                         goto retry;
234                 } 
235                 if (!rc)
236                         return false;
237         }
238         return true;
239 }
240 
241 /*
242  * In addition to knowing that we need to appraise the file in general,
243  * we need to differentiate between calling hooks, for hook specific rules.
244  */
245 static int get_subaction(struct ima_rule_entry *rule, int func)
246 {
247         if (!(rule->flags & IMA_FUNC))
248                 return IMA_FILE_APPRAISE;
249 
250         switch(func) {
251         case MMAP_CHECK:
252                 return IMA_MMAP_APPRAISE;
253         case BPRM_CHECK:
254                 return IMA_BPRM_APPRAISE;
255         case MODULE_CHECK:
256                 return IMA_MODULE_APPRAISE;
257         case FILE_CHECK:
258         default:
259                 return IMA_FILE_APPRAISE;
260         }
261 }
262 
263 /**
264  * ima_match_policy - decision based on LSM and other conditions
265  * @inode: pointer to an inode for which the policy decision is being made
266  * @func: IMA hook identifier
267  * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
268  *
269  * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
270  * conditions.
271  *
272  * (There is no need for locking when walking the policy list,
273  * as elements in the list are never deleted, nor does the list
274  * change.)
275  */
276 int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
277                      int flags)
278 {
279         struct ima_rule_entry *entry;
280         int action = 0, actmask = flags | (flags << 1);
281 
282         list_for_each_entry(entry, ima_rules, list) {
283 
284                 if (!(entry->action & actmask))
285                         continue;
286 
287                 if (!ima_match_rules(entry, inode, func, mask))
288                         continue;
289 
290                 action |= entry->flags & IMA_ACTION_FLAGS;
291 
292                 action |= entry->action & IMA_DO_MASK;
293                 if (entry->action & IMA_APPRAISE)
294                         action |= get_subaction(entry, func);
295 
296                 if (entry->action & IMA_DO_MASK)
297                         actmask &= ~(entry->action | entry->action << 1);
298                 else
299                         actmask &= ~(entry->action | entry->action >> 1);
300 
301                 if (!actmask)
302                         break;
303         }
304 
305         return action;
306 }
307 
308 /**
309  * ima_init_policy - initialize the default measure rules.
310  *
311  * ima_rules points to either the ima_default_rules or the
312  * the new ima_policy_rules.
313  */
314 void __init ima_init_policy(void)
315 {
316         int i, measure_entries, appraise_entries;
317 
318         /* if !ima_use_tcb set entries = 0 so we load NO default rules */
319         measure_entries = ima_use_tcb ? ARRAY_SIZE(default_rules) : 0;
320         appraise_entries = ima_use_appraise_tcb ?
321                          ARRAY_SIZE(default_appraise_rules) : 0;
322         
323         for (i = 0; i < measure_entries + appraise_entries; i++) {
324                 if (i < measure_entries)
325                         list_add_tail(&default_rules[i].list,
326                                       &ima_default_rules);
327                 else {
328                         int j = i - measure_entries;
329 
330                         list_add_tail(&default_appraise_rules[j].list,
331                                       &ima_default_rules);
332                 }
333         }
334 
335         ima_rules = &ima_default_rules;
336 }
337 
338 /**
339  * ima_update_policy - update default_rules with new measure rules
340  *
341  * Called on file .release to update the default rules with a complete new
342  * policy.  Once updated, the policy is locked, no additional rules can be
343  * added to the policy.
344  */
345 void ima_update_policy(void)
346 {
347         const char *op = "policy_update";
348         const char *cause = "already exists";
349         int result = 1;
350         int audit_info = 0;
351 
352         if (ima_rules == &ima_default_rules) {
353                 ima_rules = &ima_policy_rules;
354                 cause = "complete";
355                 result = 0;
356         }
357         integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
358                             NULL, op, cause, result, audit_info);
359 }
360 
361 enum {
362         Opt_err = -1,
363         Opt_measure = 1, Opt_dont_measure,
364         Opt_appraise, Opt_dont_appraise,
365         Opt_audit,
366         Opt_obj_user, Opt_obj_role, Opt_obj_type,
367         Opt_subj_user, Opt_subj_role, Opt_subj_type,
368         Opt_func, Opt_mask, Opt_fsmagic,
369         Opt_uid, Opt_euid, Opt_fowner,
370         Opt_appraise_type, Opt_fsuuid, Opt_permit_directio
371 };
372 
373 static match_table_t policy_tokens = {
374         {Opt_measure, "measure"},
375         {Opt_dont_measure, "dont_measure"},
376         {Opt_appraise, "appraise"},
377         {Opt_dont_appraise, "dont_appraise"},
378         {Opt_audit, "audit"},
379         {Opt_obj_user, "obj_user=%s"},
380         {Opt_obj_role, "obj_role=%s"},
381         {Opt_obj_type, "obj_type=%s"},
382         {Opt_subj_user, "subj_user=%s"},
383         {Opt_subj_role, "subj_role=%s"},
384         {Opt_subj_type, "subj_type=%s"},
385         {Opt_func, "func=%s"},
386         {Opt_mask, "mask=%s"},
387         {Opt_fsmagic, "fsmagic=%s"},
388         {Opt_fsuuid, "fsuuid=%s"},
389         {Opt_uid, "uid=%s"},
390         {Opt_euid, "euid=%s"},
391         {Opt_fowner, "fowner=%s"},
392         {Opt_appraise_type, "appraise_type=%s"},
393         {Opt_permit_directio, "permit_directio"},
394         {Opt_err, NULL}
395 };
396 
397 static int ima_lsm_rule_init(struct ima_rule_entry *entry,
398                              substring_t *args, int lsm_rule, int audit_type)
399 {
400         int result;
401 
402         if (entry->lsm[lsm_rule].rule)
403                 return -EINVAL;
404 
405         entry->lsm[lsm_rule].args_p = match_strdup(args);
406         if (!entry->lsm[lsm_rule].args_p)
407                 return -ENOMEM;
408 
409         entry->lsm[lsm_rule].type = audit_type;
410         result = security_filter_rule_init(entry->lsm[lsm_rule].type,
411                                            Audit_equal,
412                                            entry->lsm[lsm_rule].args_p,
413                                            &entry->lsm[lsm_rule].rule);
414         if (!entry->lsm[lsm_rule].rule) {
415                 kfree(entry->lsm[lsm_rule].args_p);
416                 return -EINVAL;
417         }
418 
419         return result;
420 }
421 
422 static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
423 {
424         audit_log_format(ab, "%s=", key);
425         audit_log_untrustedstring(ab, value);
426         audit_log_format(ab, " ");
427 }
428 
429 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
430 {
431         struct audit_buffer *ab;
432         char *from;
433         char *p;
434         int result = 0;
435 
436         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);
437 
438         entry->uid = INVALID_UID;
439         entry->fowner = INVALID_UID;
440         entry->action = UNKNOWN;
441         while ((p = strsep(&rule, " \t")) != NULL) {
442                 substring_t args[MAX_OPT_ARGS];
443                 int token;
444                 unsigned long lnum;
445 
446                 if (result < 0)
447                         break;
448                 if ((*p == '\0') || (*p == ' ') || (*p == '\t'))
449                         continue;
450                 token = match_token(p, policy_tokens, args);
451                 switch (token) {
452                 case Opt_measure:
453                         ima_log_string(ab, "action", "measure");
454 
455                         if (entry->action != UNKNOWN)
456                                 result = -EINVAL;
457 
458                         entry->action = MEASURE;
459                         break;
460                 case Opt_dont_measure:
461                         ima_log_string(ab, "action", "dont_measure");
462 
463                         if (entry->action != UNKNOWN)
464                                 result = -EINVAL;
465 
466                         entry->action = DONT_MEASURE;
467                         break;
468                 case Opt_appraise:
469                         ima_log_string(ab, "action", "appraise");
470 
471                         if (entry->action != UNKNOWN)
472                                 result = -EINVAL;
473 
474                         entry->action = APPRAISE;
475                         break;
476                 case Opt_dont_appraise:
477                         ima_log_string(ab, "action", "dont_appraise");
478 
479                         if (entry->action != UNKNOWN)
480                                 result = -EINVAL;
481 
482                         entry->action = DONT_APPRAISE;
483                         break;
484                 case Opt_audit:
485                         ima_log_string(ab, "action", "audit");
486 
487                         if (entry->action != UNKNOWN)
488                                 result = -EINVAL;
489 
490                         entry->action = AUDIT;
491                         break;
492                 case Opt_func:
493                         ima_log_string(ab, "func", args[0].from);
494 
495                         if (entry->func)
496                                 result = -EINVAL;
497 
498                         if (strcmp(args[0].from, "FILE_CHECK") == 0)
499                                 entry->func = FILE_CHECK;
500                         /* PATH_CHECK is for backwards compat */
501                         else if (strcmp(args[0].from, "PATH_CHECK") == 0)
502                                 entry->func = FILE_CHECK;
503                         else if (strcmp(args[0].from, "MODULE_CHECK") == 0)
504                                 entry->func = MODULE_CHECK;
505                         else if ((strcmp(args[0].from, "FILE_MMAP") == 0)
506                                 || (strcmp(args[0].from, "MMAP_CHECK") == 0))
507                                 entry->func = MMAP_CHECK;
508                         else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
509                                 entry->func = BPRM_CHECK;
510                         else
511                                 result = -EINVAL;
512                         if (!result)
513                                 entry->flags |= IMA_FUNC;
514                         break;
515                 case Opt_mask:
516                         ima_log_string(ab, "mask", args[0].from);
517 
518                         if (entry->mask)
519                                 result = -EINVAL;
520 
521                         from = args[0].from;
522                         if (*from == '^')
523                                 from++;
524 
525                         if ((strcmp(from, "MAY_EXEC")) == 0)
526                                 entry->mask = MAY_EXEC;
527                         else if (strcmp(from, "MAY_WRITE") == 0)
528                                 entry->mask = MAY_WRITE;
529                         else if (strcmp(from, "MAY_READ") == 0)
530                                 entry->mask = MAY_READ;
531                         else if (strcmp(from, "MAY_APPEND") == 0)
532                                 entry->mask = MAY_APPEND;
533                         else
534                                 result = -EINVAL;
535                         if (!result)
536                                 entry->flags |= (*args[0].from == '^')
537                                      ? IMA_INMASK : IMA_MASK;
538                         break;
539                 case Opt_fsmagic:
540                         ima_log_string(ab, "fsmagic", args[0].from);
541 
542                         if (entry->fsmagic) {
543                                 result = -EINVAL;
544                                 break;
545                         }
546 
547                         result = strict_strtoul(args[0].from, 16,
548                                                 &entry->fsmagic);
549                         if (!result)
550                                 entry->flags |= IMA_FSMAGIC;
551                         break;
552                 case Opt_fsuuid:
553                         ima_log_string(ab, "fsuuid", args[0].from);
554 
555                         if (memchr_inv(entry->fsuuid, 0x00,
556                                        sizeof(entry->fsuuid))) {
557                                 result = -EINVAL;
558                                 break;
559                         }
560 
561                         result = blk_part_pack_uuid(args[0].from,
562                                                     entry->fsuuid);
563                         if (!result)
564                                 entry->flags |= IMA_FSUUID;
565                         break;
566                 case Opt_uid:
567                         ima_log_string(ab, "uid", args[0].from);
568                 case Opt_euid:
569                         if (token == Opt_euid)
570                                 ima_log_string(ab, "euid", args[0].from);
571 
572                         if (uid_valid(entry->uid)) {
573                                 result = -EINVAL;
574                                 break;
575                         }
576 
577                         result = strict_strtoul(args[0].from, 10, &lnum);
578                         if (!result) {
579                                 entry->uid = make_kuid(current_user_ns(),
580                                                        (uid_t) lnum);
581                                 if (!uid_valid(entry->uid) ||
582                                     (uid_t)lnum != lnum)
583                                         result = -EINVAL;
584                                 else
585                                         entry->flags |= (token == Opt_uid)
586                                             ? IMA_UID : IMA_EUID;
587                         }
588                         break;
589                 case Opt_fowner:
590                         ima_log_string(ab, "fowner", args[0].from);
591 
592                         if (uid_valid(entry->fowner)) {
593                                 result = -EINVAL;
594                                 break;
595                         }
596 
597                         result = strict_strtoul(args[0].from, 10, &lnum);
598                         if (!result) {
599                                 entry->fowner = make_kuid(current_user_ns(), (uid_t)lnum);
600                                 if (!uid_valid(entry->fowner) || (((uid_t)lnum) != lnum))
601                                         result = -EINVAL;
602                                 else
603                                         entry->flags |= IMA_FOWNER;
604                         }
605                         break;
606                 case Opt_obj_user:
607                         ima_log_string(ab, "obj_user", args[0].from);
608                         result = ima_lsm_rule_init(entry, args,
609                                                    LSM_OBJ_USER,
610                                                    AUDIT_OBJ_USER);
611                         break;
612                 case Opt_obj_role:
613                         ima_log_string(ab, "obj_role", args[0].from);
614                         result = ima_lsm_rule_init(entry, args,
615                                                    LSM_OBJ_ROLE,
616                                                    AUDIT_OBJ_ROLE);
617                         break;
618                 case Opt_obj_type:
619                         ima_log_string(ab, "obj_type", args[0].from);
620                         result = ima_lsm_rule_init(entry, args,
621                                                    LSM_OBJ_TYPE,
622                                                    AUDIT_OBJ_TYPE);
623                         break;
624                 case Opt_subj_user:
625                         ima_log_string(ab, "subj_user", args[0].from);
626                         result = ima_lsm_rule_init(entry, args,
627                                                    LSM_SUBJ_USER,
628                                                    AUDIT_SUBJ_USER);
629                         break;
630                 case Opt_subj_role:
631                         ima_log_string(ab, "subj_role", args[0].from);
632                         result = ima_lsm_rule_init(entry, args,
633                                                    LSM_SUBJ_ROLE,
634                                                    AUDIT_SUBJ_ROLE);
635                         break;
636                 case Opt_subj_type:
637                         ima_log_string(ab, "subj_type", args[0].from);
638                         result = ima_lsm_rule_init(entry, args,
639                                                    LSM_SUBJ_TYPE,
640                                                    AUDIT_SUBJ_TYPE);
641                         break;
642                 case Opt_appraise_type:
643                         if (entry->action != APPRAISE) {
644                                 result = -EINVAL;
645                                 break;
646                         }
647 
648                         ima_log_string(ab, "appraise_type", args[0].from);
649                         if ((strcmp(args[0].from, "imasig")) == 0)
650                                 entry->flags |= IMA_DIGSIG_REQUIRED;
651                         else
652                                 result = -EINVAL;
653                         break;
654                 case Opt_permit_directio:
655                         entry->flags |= IMA_PERMIT_DIRECTIO;
656                         break;
657                 case Opt_err:
658                         ima_log_string(ab, "UNKNOWN", p);
659                         result = -EINVAL;
660                         break;
661                 }
662         }
663         if (!result && (entry->action == UNKNOWN))
664                 result = -EINVAL;
665         else if (entry->func == MODULE_CHECK)
666                 ima_appraise |= IMA_APPRAISE_MODULES;
667         audit_log_format(ab, "res=%d", !result);
668         audit_log_end(ab);
669         return result;
670 }
671 
672 /**
673  * ima_parse_add_rule - add a rule to ima_policy_rules
674  * @rule - ima measurement policy rule
675  *
676  * Uses a mutex to protect the policy list from multiple concurrent writers.
677  * Returns the length of the rule parsed, an error code on failure
678  */
679 ssize_t ima_parse_add_rule(char *rule)
680 {
681         const char *op = "update_policy";
682         char *p;
683         struct ima_rule_entry *entry;
684         ssize_t result, len;
685         int audit_info = 0;
686 
687         /* Prevent installed policy from changing */
688         if (ima_rules != &ima_default_rules) {
689                 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
690                                     NULL, op, "already exists",
691                                     -EACCES, audit_info);
692                 return -EACCES;
693         }
694 
695         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
696         if (!entry) {
697                 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
698                                     NULL, op, "-ENOMEM", -ENOMEM, audit_info);
699                 return -ENOMEM;
700         }
701 
702         INIT_LIST_HEAD(&entry->list);
703 
704         p = strsep(&rule, "\n");
705         len = strlen(p) + 1;
706 
707         if (*p == '#') {
708                 kfree(entry);
709                 return len;
710         }
711 
712         result = ima_parse_rule(p, entry);
713         if (result) {
714                 kfree(entry);
715                 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
716                                     NULL, op, "invalid policy", result,
717                                     audit_info);
718                 return result;
719         }
720 
721         mutex_lock(&ima_rules_mutex);
722         list_add_tail(&entry->list, &ima_policy_rules);
723         mutex_unlock(&ima_rules_mutex);
724 
725         return len;
726 }
727 
728 /* ima_delete_rules called to cleanup invalid policy */
729 void ima_delete_rules(void)
730 {
731         struct ima_rule_entry *entry, *tmp;
732         int i;
733 
734         mutex_lock(&ima_rules_mutex);
735         list_for_each_entry_safe(entry, tmp, &ima_policy_rules, list) {
736                 for (i = 0; i < MAX_LSM_RULES; i++)
737                         kfree(entry->lsm[i].args_p);
738 
739                 list_del(&entry->list);
740                 kfree(entry);
741         }
742         mutex_unlock(&ima_rules_mutex);
743 }
744 

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