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 = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
  77         {.action = DONT_MEASURE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
  78         {.action = DONT_MEASURE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
  79         {.action = DONT_MEASURE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
  80         {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
  81          .flags = IMA_FUNC | IMA_MASK},
  82         {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
  83          .flags = IMA_FUNC | IMA_MASK},
  84         {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ, .uid = GLOBAL_ROOT_UID,
  85          .flags = IMA_FUNC | IMA_MASK | IMA_UID},
  86         {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
  87 };
  88
  89 static struct ima_rule_entry default_appraise_rules[] = {
  90         {.action = DONT_APPRAISE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
  91         {.action = DONT_APPRAISE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
  92         {.action = DONT_APPRAISE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
  93         {.action = DONT_APPRAISE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
  94         {.action = DONT_APPRAISE, .fsmagic = RAMFS_MAGIC, .flags = IMA_FSMAGIC},
  95         {.action = DONT_APPRAISE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
  96         {.action = DONT_APPRAISE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
  97         {.action = DONT_APPRAISE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
  98         {.action = DONT_APPRAISE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
  99         {.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 100         {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .flags = IMA_FOWNER},
 101 };
 102
 103 static LIST_HEAD(ima_default_rules);
 104 static LIST_HEAD(ima_policy_rules);
 105 static struct list_head *ima_rules;
 106
 107 static DEFINE_MUTEX(ima_rules_mutex);
 108
 109 static bool ima_use_tcb __initdata;
 110 static int __init default_measure_policy_setup(char *str)
 111 {
 112         ima_use_tcb = 1;
 113         return 1;
 114 }
 115 __setup("ima_tcb", default_measure_policy_setup);
 116
 117 static bool ima_use_appraise_tcb __initdata;
 118 static int __init default_appraise_policy_setup(char *str)
 119 {
 120         ima_use_appraise_tcb = 1;
 121         return 1;
 122 }
 123 __setup("ima_appraise_tcb", default_appraise_policy_setup);
 124
 125 /*
 126  * Although the IMA policy does not change, the LSM policy can be
 127  * reloaded, leaving the IMA LSM based rules referring to the old,
 128  * stale LSM policy.
 129  *
 130  * Update the IMA LSM based rules to reflect the reloaded LSM policy.
 131  * We assume the rules still exist; and BUG_ON() if they don't.
 132  */
 133 static void ima_lsm_update_rules(void)
 134 {
 135         struct ima_rule_entry *entry, *tmp;
 136         int result;
 137         int i;
 138
 139         mutex_lock(&ima_rules_mutex);
 140         list_for_each_entry_safe(entry, tmp, &ima_policy_rules, list) {
 141                 for (i = 0; i < MAX_LSM_RULES; i++) {
 142                         if (!entry->lsm[i].rule)
 143                                 continue;
 144                         result = security_filter_rule_init(entry->lsm[i].type,
 145                                                            Audit_equal,
 146                                                            entry->lsm[i].args_p,
 147                                                            &entry->lsm[i].rule);
 148                         BUG_ON(!entry->lsm[i].rule);
 149                 }
 150         }
 151         mutex_unlock(&ima_rules_mutex);
 152 }
 153
 154 /**
 155  * ima_match_rules - determine whether an inode matches the measure rule.
 156  * @rule: a pointer to a rule
 157  * @inode: a pointer to an inode
 158  * @func: LIM hook identifier
 159  * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
 160  *
 161  * Returns true on rule match, false on failure.
 162  */
 163 static bool ima_match_rules(struct ima_rule_entry *rule,
 164                             struct inode *inode, enum ima_hooks func, int mask)
 165 {
 166         struct task_struct *tsk = current;
 167         const struct cred *cred = current_cred();
 168         int i;
 169
 170         if ((rule->flags & IMA_FUNC) &&
 171             (rule->func != func && func != POST_SETATTR))
 172                 return false;
 173         if ((rule->flags & IMA_MASK) &&
 174             (rule->mask != mask && func != POST_SETATTR))
 175                 return false;
 176         if ((rule->flags & IMA_FSMAGIC)
 177             && rule->fsmagic != inode->i_sb->s_magic)
 178                 return false;
 179         if ((rule->flags & IMA_FSUUID) &&
 180             memcmp(rule->fsuuid, inode->i_sb->s_uuid, sizeof(rule->fsuuid)))
 181                 return false;
 182         if ((rule->flags & IMA_UID) && !uid_eq(rule->uid, cred->uid))
 183                 return false;
 184         if ((rule->flags & IMA_FOWNER) && !uid_eq(rule->fowner, inode->i_uid))
 185                 return false;
 186         for (i = 0; i < MAX_LSM_RULES; i++) {
 187                 int rc = 0;
 188                 u32 osid, sid;
 189                 int retried = 0;
 190
 191                 if (!rule->lsm[i].rule)
 192                         continue;
 193 retry:
 194                 switch (i) {
 195                 case LSM_OBJ_USER:
 196                 case LSM_OBJ_ROLE:
 197                 case LSM_OBJ_TYPE:
 198                         security_inode_getsecid(inode, &osid);
 199                         rc = security_filter_rule_match(osid,
 200                                                         rule->lsm[i].type,
 201                                                         Audit_equal,
 202                                                         rule->lsm[i].rule,
 203                                                         NULL);
 204                         break;
 205                 case LSM_SUBJ_USER:
 206                 case LSM_SUBJ_ROLE:
 207                 case LSM_SUBJ_TYPE:
 208                         security_task_getsecid(tsk, &sid);
 209                         rc = security_filter_rule_match(sid,
 210                                                         rule->lsm[i].type,
 211                                                         Audit_equal,
 212                                                         rule->lsm[i].rule,
 213                                                         NULL);
 214                 default:
 215                         break;
 216                 }
 217                 if ((rc < 0) && (!retried)) {
 218                         retried = 1;
 219                         ima_lsm_update_rules();
 220                         goto retry;
 221                 }
 222                 if (!rc)
 223                         return false;
 224         }
 225         return true;
 226 }
 227
 228 /*
 229  * In addition to knowing that we need to appraise the file in general,
 230  * we need to differentiate between calling hooks, for hook specific rules.
 231  */
 232 static int get_subaction(struct ima_rule_entry *rule, int func)
 233 {
 234         if (!(rule->flags & IMA_FUNC))
 235                 return IMA_FILE_APPRAISE;
 236
 237         switch (func) {
 238         case MMAP_CHECK:
 239                 return IMA_MMAP_APPRAISE;
 240         case BPRM_CHECK:
 241                 return IMA_BPRM_APPRAISE;
 242         case MODULE_CHECK:
 243                 return IMA_MODULE_APPRAISE;
 244         case FILE_CHECK:
 245         default:
 246                 return IMA_FILE_APPRAISE;
 247         }
 248 }
 249
 250 /**
 251  * ima_match_policy - decision based on LSM and other conditions
 252  * @inode: pointer to an inode for which the policy decision is being made
 253  * @func: IMA hook identifier
 254  * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
 255  *
 256  * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
 257  * conditions.
 258  *
 259  * (There is no need for locking when walking the policy list,
 260  * as elements in the list are never deleted, nor does the list
 261  * change.)
 262  */
 263 int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
 264                      int flags)
 265 {
 266         struct ima_rule_entry *entry;
 267         int action = 0, actmask = flags | (flags << 1);
 268
 269         list_for_each_entry(entry, ima_rules, list) {
 270
 271                 if (!(entry->action & actmask))
 272                         continue;
 273
 274                 if (!ima_match_rules(entry, inode, func, mask))
 275                         continue;
 276
 277                 action |= entry->flags & IMA_ACTION_FLAGS;
 278
 279                 action |= entry->action & IMA_DO_MASK;
 280                 if (entry->action & IMA_APPRAISE)
 281                         action |= get_subaction(entry, func);
 282
 283                 if (entry->action & IMA_DO_MASK)
 284                         actmask &= ~(entry->action | entry->action << 1);
 285                 else
 286                         actmask &= ~(entry->action | entry->action >> 1);
 287
 288                 if (!actmask)
 289                         break;
 290         }
 291
 292         return action;
 293 }
 294
 295 /**
 296  * ima_init_policy - initialize the default measure rules.
 297  *
 298  * ima_rules points to either the ima_default_rules or the
 299  * the new ima_policy_rules.
 300  */
 301 void __init ima_init_policy(void)
 302 {
 303         int i, measure_entries, appraise_entries;
 304
 305         /* if !ima_use_tcb set entries = 0 so we load NO default rules */
 306         measure_entries = ima_use_tcb ? ARRAY_SIZE(default_rules) : 0;
 307         appraise_entries = ima_use_appraise_tcb ?
 308                          ARRAY_SIZE(default_appraise_rules) : 0;
 309
 310         for (i = 0; i < measure_entries + appraise_entries; i++) {
 311                 if (i < measure_entries)
 312                         list_add_tail(&default_rules[i].list,
 313                                       &ima_default_rules);
 314                 else {
 315                         int j = i - measure_entries;
 316
 317                         list_add_tail(&default_appraise_rules[j].list,
 318                                       &ima_default_rules);
 319                 }
 320         }
 321
 322         ima_rules = &ima_default_rules;
 323 }
 324
 325 /**
 326  * ima_update_policy - update default_rules with new measure rules
 327  *
 328  * Called on file .release to update the default rules with a complete new
 329  * policy.  Once updated, the policy is locked, no additional rules can be
 330  * added to the policy.
 331  */
 332 void ima_update_policy(void)
 333 {
 334         static const char op[] = "policy_update";
 335         const char *cause = "already exists";
 336         int result = 1;
 337         int audit_info = 0;
 338
 339         if (ima_rules == &ima_default_rules) {
 340                 ima_rules = &ima_policy_rules;
 341                 cause = "complete";
 342                 result = 0;
 343         }
 344         integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
 345                             NULL, op, cause, result, audit_info);
 346 }
 347
 348 enum {
 349         Opt_err = -1,
 350         Opt_measure = 1, Opt_dont_measure,
 351         Opt_appraise, Opt_dont_appraise,
 352         Opt_audit,
 353         Opt_obj_user, Opt_obj_role, Opt_obj_type,
 354         Opt_subj_user, Opt_subj_role, Opt_subj_type,
 355         Opt_func, Opt_mask, Opt_fsmagic, Opt_uid, Opt_fowner,
 356         Opt_appraise_type, Opt_fsuuid
 357 };
 358
 359 static match_table_t policy_tokens = {
 360         {Opt_measure, "measure"},
 361         {Opt_dont_measure, "dont_measure"},
 362         {Opt_appraise, "appraise"},
 363         {Opt_dont_appraise, "dont_appraise"},
 364         {Opt_audit, "audit"},
 365         {Opt_obj_user, "obj_user=%s"},
 366         {Opt_obj_role, "obj_role=%s"},
 367         {Opt_obj_type, "obj_type=%s"},
 368         {Opt_subj_user, "subj_user=%s"},
 369         {Opt_subj_role, "subj_role=%s"},
 370         {Opt_subj_type, "subj_type=%s"},
 371         {Opt_func, "func=%s"},
 372         {Opt_mask, "mask=%s"},
 373         {Opt_fsmagic, "fsmagic=%s"},
 374         {Opt_fsuuid, "fsuuid=%s"},
 375         {Opt_uid, "uid=%s"},
 376         {Opt_fowner, "fowner=%s"},
 377         {Opt_appraise_type, "appraise_type=%s"},
 378         {Opt_err, NULL}
 379 };
 380
 381 static int ima_lsm_rule_init(struct ima_rule_entry *entry,
 382                              substring_t *args, int lsm_rule, int audit_type)
 383 {
 384         int result;
 385
 386         if (entry->lsm[lsm_rule].rule)
 387                 return -EINVAL;
 388
 389         entry->lsm[lsm_rule].args_p = match_strdup(args);
 390         if (!entry->lsm[lsm_rule].args_p)
 391                 return -ENOMEM;
 392
 393         entry->lsm[lsm_rule].type = audit_type;
 394         result = security_filter_rule_init(entry->lsm[lsm_rule].type,
 395                                            Audit_equal,
 396                                            entry->lsm[lsm_rule].args_p,
 397                                            &entry->lsm[lsm_rule].rule);
 398         if (!entry->lsm[lsm_rule].rule) {
 399                 kfree(entry->lsm[lsm_rule].args_p);
 400                 return -EINVAL;
 401         }
 402
 403         return result;
 404 }
 405
 406 static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
 407 {
 408         audit_log_format(ab, "%s=", key);
 409         audit_log_untrustedstring(ab, value);
 410         audit_log_format(ab, " ");
 411 }
 412
 413 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 414 {
 415         struct audit_buffer *ab;
 416         char *p;
 417         int result = 0;
 418
 419         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);
 420
 421         entry->uid = INVALID_UID;
 422         entry->fowner = INVALID_UID;
 423         entry->action = UNKNOWN;
 424         while ((p = strsep(&rule, " \t")) != NULL) {
 425                 substring_t args[MAX_OPT_ARGS];
 426                 int token;
 427                 unsigned long lnum;
 428
 429                 if (result < 0)
 430                         break;
 431                 if ((*p == '\0') || (*p == ' ') || (*p == '\t'))
 432                         continue;
 433                 token = match_token(p, policy_tokens, args);
 434                 switch (token) {
 435                 case Opt_measure:
 436                         ima_log_string(ab, "action", "measure");
 437
 438                         if (entry->action != UNKNOWN)
 439                                 result = -EINVAL;
 440
 441                         entry->action = MEASURE;
 442                         break;
 443                 case Opt_dont_measure:
 444                         ima_log_string(ab, "action", "dont_measure");
 445
 446                         if (entry->action != UNKNOWN)
 447                                 result = -EINVAL;
 448
 449                         entry->action = DONT_MEASURE;
 450                         break;
 451                 case Opt_appraise:
 452                         ima_log_string(ab, "action", "appraise");
 453
 454                         if (entry->action != UNKNOWN)
 455                                 result = -EINVAL;
 456
 457                         entry->action = APPRAISE;
 458                         break;
 459                 case Opt_dont_appraise:
 460                         ima_log_string(ab, "action", "dont_appraise");
 461
 462                         if (entry->action != UNKNOWN)
 463                                 result = -EINVAL;
 464
 465                         entry->action = DONT_APPRAISE;
 466                         break;
 467                 case Opt_audit:
 468                         ima_log_string(ab, "action", "audit");
 469
 470                         if (entry->action != UNKNOWN)
 471                                 result = -EINVAL;
 472
 473                         entry->action = AUDIT;
 474                         break;
 475                 case Opt_func:
 476                         ima_log_string(ab, "func", args[0].from);
 477
 478                         if (entry->func)
 479                                 result = -EINVAL;
 480
 481                         if (strcmp(args[0].from, "FILE_CHECK") == 0)
 482                                 entry->func = FILE_CHECK;
 483                         /* PATH_CHECK is for backwards compat */
 484                         else if (strcmp(args[0].from, "PATH_CHECK") == 0)
 485                                 entry->func = FILE_CHECK;
 486                         else if (strcmp(args[0].from, "MODULE_CHECK") == 0)
 487                                 entry->func = MODULE_CHECK;
 488                         else if ((strcmp(args[0].from, "FILE_MMAP") == 0)
 489                                 || (strcmp(args[0].from, "MMAP_CHECK") == 0))
 490                                 entry->func = MMAP_CHECK;
 491                         else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
 492                                 entry->func = BPRM_CHECK;
 493                         else
 494                                 result = -EINVAL;
 495                         if (!result)
 496                                 entry->flags |= IMA_FUNC;
 497                         break;
 498                 case Opt_mask:
 499                         ima_log_string(ab, "mask", args[0].from);
 500
 501                         if (entry->mask)
 502                                 result = -EINVAL;
 503
 504                         if ((strcmp(args[0].from, "MAY_EXEC")) == 0)
 505                                 entry->mask = MAY_EXEC;
 506                         else if (strcmp(args[0].from, "MAY_WRITE") == 0)
 507                                 entry->mask = MAY_WRITE;
 508                         else if (strcmp(args[0].from, "MAY_READ") == 0)
 509                                 entry->mask = MAY_READ;
 510                         else if (strcmp(args[0].from, "MAY_APPEND") == 0)
 511                                 entry->mask = MAY_APPEND;
 512                         else
 513                                 result = -EINVAL;
 514                         if (!result)
 515                                 entry->flags |= IMA_MASK;
 516                         break;
 517                 case Opt_fsmagic:
 518                         ima_log_string(ab, "fsmagic", args[0].from);
 519
 520                         if (entry->fsmagic) {
 521                                 result = -EINVAL;
 522                                 break;
 523                         }
 524
 525                         result = kstrtoul(args[0].from, 16, &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 = kstrtoul(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 = kstrtoul(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         static 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 }