security/integrity/ima/ima_policy.c

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