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) && rule->func != func)
 171                 return false;
 172         if ((rule->flags & IMA_MASK) && rule->mask != mask)
 173                 return false;
 174         if ((rule->flags & IMA_FSMAGIC)
 175             && rule->fsmagic != inode->i_sb->s_magic)
 176                 return false;
 177         if ((rule->flags & IMA_FSUUID) &&
 178             memcmp(rule->fsuuid, inode->i_sb->s_uuid, sizeof(rule->fsuuid)))
 179                 return false;
 180         if ((rule->flags & IMA_UID) && !uid_eq(rule->uid, cred->uid))
 181                 return false;
 182         if ((rule->flags & IMA_FOWNER) && !uid_eq(rule->fowner, inode->i_uid))
 183                 return false;
 184         for (i = 0; i < MAX_LSM_RULES; i++) {
 185                 int rc = 0;
 186                 u32 osid, sid;
 187                 int retried = 0;
 188
 189                 if (!rule->lsm[i].rule)
 190                         continue;
 191 retry:
 192                 switch (i) {
 193                 case LSM_OBJ_USER:
 194                 case LSM_OBJ_ROLE:
 195                 case LSM_OBJ_TYPE:
 196                         security_inode_getsecid(inode, &osid);
 197                         rc = security_filter_rule_match(osid,
 198                                                         rule->lsm[i].type,
 199                                                         Audit_equal,
 200                                                         rule->lsm[i].rule,
 201                                                         NULL);
 202                         break;
 203                 case LSM_SUBJ_USER:
 204                 case LSM_SUBJ_ROLE:
 205                 case LSM_SUBJ_TYPE:
 206                         security_task_getsecid(tsk, &sid);
 207                         rc = security_filter_rule_match(sid,
 208                                                         rule->lsm[i].type,
 209                                                         Audit_equal,
 210                                                         rule->lsm[i].rule,
 211                                                         NULL);
 212                 default:
 213                         break;
 214                 }
 215                 if ((rc < 0) && (!retried)) {
 216                         retried = 1;
 217                         ima_lsm_update_rules();
 218                         goto retry;
 219                 }
 220                 if (!rc)
 221                         return false;
 222         }
 223         return true;
 224 }
 225
 226 /*
 227  * In addition to knowing that we need to appraise the file in general,
 228  * we need to differentiate between calling hooks, for hook specific rules.
 229  */
 230 static int get_subaction(struct ima_rule_entry *rule, int func)
 231 {
 232         if (!(rule->flags & IMA_FUNC))
 233                 return IMA_FILE_APPRAISE;
 234
 235         switch(func) {
 236         case MMAP_CHECK:
 237                 return IMA_MMAP_APPRAISE;
 238         case BPRM_CHECK:
 239                 return IMA_BPRM_APPRAISE;
 240         case MODULE_CHECK:
 241                 return IMA_MODULE_APPRAISE;
 242         case FILE_CHECK:
 243         default:
 244                 return IMA_FILE_APPRAISE;
 245         }
 246 }
 247
 248 /**
 249  * ima_match_policy - decision based on LSM and other conditions
 250  * @inode: pointer to an inode for which the policy decision is being made
 251  * @func: IMA hook identifier
 252  * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
 253  *
 254  * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
 255  * conditions.
 256  *
 257  * (There is no need for locking when walking the policy list,
 258  * as elements in the list are never deleted, nor does the list
 259  * change.)
 260  */
 261 int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
 262                      int flags)
 263 {
 264         struct ima_rule_entry *entry;
 265         int action = 0, actmask = flags | (flags << 1);
 266
 267         list_for_each_entry(entry, ima_rules, list) {
 268
 269                 if (!(entry->action & actmask))
 270                         continue;
 271
 272                 if (!ima_match_rules(entry, inode, func, mask))
 273                         continue;
 274
 275                 action |= entry->flags & IMA_ACTION_FLAGS;
 276
 277                 action |= entry->action & IMA_DO_MASK;
 278                 if (entry->action & IMA_APPRAISE)
 279                         action |= get_subaction(entry, func);
 280
 281                 if (entry->action & IMA_DO_MASK)
 282                         actmask &= ~(entry->action | entry->action << 1);
 283                 else
 284                         actmask &= ~(entry->action | entry->action >> 1);
 285
 286                 if (!actmask)
 287                         break;
 288         }
 289
 290         return action;
 291 }
 292
 293 /**
 294  * ima_init_policy - initialize the default measure rules.
 295  *
 296  * ima_rules points to either the ima_default_rules or the
 297  * the new ima_policy_rules.
 298  */
 299 void __init ima_init_policy(void)
 300 {
 301         int i, measure_entries, appraise_entries;
 302
 303         /* if !ima_use_tcb set entries = 0 so we load NO default rules */
 304         measure_entries = ima_use_tcb ? ARRAY_SIZE(default_rules) : 0;
 305         appraise_entries = ima_use_appraise_tcb ?
 306                          ARRAY_SIZE(default_appraise_rules) : 0;
 307
 308         for (i = 0; i < measure_entries + appraise_entries; i++) {
 309                 if (i < measure_entries)
 310                         list_add_tail(&default_rules[i].list,
 311                                       &ima_default_rules);
 312                 else {
 313                         int j = i - measure_entries;
 314
 315                         list_add_tail(&default_appraise_rules[j].list,
 316                                       &ima_default_rules);
 317                 }
 318         }
 319
 320         ima_rules = &ima_default_rules;
 321 }
 322
 323 /**
 324  * ima_update_policy - update default_rules with new measure rules
 325  *
 326  * Called on file .release to update the default rules with a complete new
 327  * policy.  Once updated, the policy is locked, no additional rules can be
 328  * added to the policy.
 329  */
 330 void ima_update_policy(void)
 331 {
 332         const char *op = "policy_update";
 333         const char *cause = "already exists";
 334         int result = 1;
 335         int audit_info = 0;
 336
 337         if (ima_rules == &ima_default_rules) {
 338                 ima_rules = &ima_policy_rules;
 339                 cause = "complete";
 340                 result = 0;
 341         }
 342         integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
 343                             NULL, op, cause, result, audit_info);
 344 }
 345
 346 enum {
 347         Opt_err = -1,
 348         Opt_measure = 1, Opt_dont_measure,
 349         Opt_appraise, Opt_dont_appraise,
 350         Opt_audit,
 351         Opt_obj_user, Opt_obj_role, Opt_obj_type,
 352         Opt_subj_user, Opt_subj_role, Opt_subj_type,
 353         Opt_func, Opt_mask, Opt_fsmagic, Opt_uid, Opt_fowner,
 354         Opt_appraise_type, Opt_fsuuid
 355 };
 356
 357 static match_table_t policy_tokens = {
 358         {Opt_measure, "measure"},
 359         {Opt_dont_measure, "dont_measure"},
 360         {Opt_appraise, "appraise"},
 361         {Opt_dont_appraise, "dont_appraise"},
 362         {Opt_audit, "audit"},
 363         {Opt_obj_user, "obj_user=%s"},
 364         {Opt_obj_role, "obj_role=%s"},
 365         {Opt_obj_type, "obj_type=%s"},
 366         {Opt_subj_user, "subj_user=%s"},
 367         {Opt_subj_role, "subj_role=%s"},
 368         {Opt_subj_type, "subj_type=%s"},
 369         {Opt_func, "func=%s"},
 370         {Opt_mask, "mask=%s"},
 371         {Opt_fsmagic, "fsmagic=%s"},
 372         {Opt_fsuuid, "fsuuid=%s"},
 373         {Opt_uid, "uid=%s"},
 374         {Opt_fowner, "fowner=%s"},
 375         {Opt_appraise_type, "appraise_type=%s"},
 376         {Opt_err, NULL}
 377 };
 378
 379 static int ima_lsm_rule_init(struct ima_rule_entry *entry,
 380                              substring_t *args, int lsm_rule, int audit_type)
 381 {
 382         int result;
 383
 384         if (entry->lsm[lsm_rule].rule)
 385                 return -EINVAL;
 386
 387         entry->lsm[lsm_rule].args_p = match_strdup(args);
 388         if (!entry->lsm[lsm_rule].args_p)
 389                 return -ENOMEM;
 390
 391         entry->lsm[lsm_rule].type = audit_type;
 392         result = security_filter_rule_init(entry->lsm[lsm_rule].type,
 393                                            Audit_equal,
 394                                            entry->lsm[lsm_rule].args_p,
 395                                            &entry->lsm[lsm_rule].rule);
 396         if (!entry->lsm[lsm_rule].rule) {
 397                 kfree(entry->lsm[lsm_rule].args_p);
 398                 return -EINVAL;
 399         }
 400
 401         return result;
 402 }
 403
 404 static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
 405 {
 406         audit_log_format(ab, "%s=", key);
 407         audit_log_untrustedstring(ab, value);
 408         audit_log_format(ab, " ");
 409 }
 410
 411 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 412 {
 413         struct audit_buffer *ab;
 414         char *p;
 415         int result = 0;
 416
 417         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);
 418
 419         entry->uid = INVALID_UID;
 420         entry->fowner = INVALID_UID;
 421         entry->action = UNKNOWN;
 422         while ((p = strsep(&rule, " \t")) != NULL) {
 423                 substring_t args[MAX_OPT_ARGS];
 424                 int token;
 425                 unsigned long lnum;
 426
 427                 if (result < 0)
 428                         break;
 429                 if ((*p == '\0') || (*p == ' ') || (*p == '\t'))
 430                         continue;
 431                 token = match_token(p, policy_tokens, args);
 432                 switch (token) {
 433                 case Opt_measure:
 434                         ima_log_string(ab, "action", "measure");
 435
 436                         if (entry->action != UNKNOWN)
 437                                 result = -EINVAL;
 438
 439                         entry->action = MEASURE;
 440                         break;
 441                 case Opt_dont_measure:
 442                         ima_log_string(ab, "action", "dont_measure");
 443
 444                         if (entry->action != UNKNOWN)
 445                                 result = -EINVAL;
 446
 447                         entry->action = DONT_MEASURE;
 448                         break;
 449                 case Opt_appraise:
 450                         ima_log_string(ab, "action", "appraise");
 451
 452                         if (entry->action != UNKNOWN)
 453                                 result = -EINVAL;
 454
 455                         entry->action = APPRAISE;
 456                         break;
 457                 case Opt_dont_appraise:
 458                         ima_log_string(ab, "action", "dont_appraise");
 459
 460                         if (entry->action != UNKNOWN)
 461                                 result = -EINVAL;
 462
 463                         entry->action = DONT_APPRAISE;
 464                         break;
 465                 case Opt_audit:
 466                         ima_log_string(ab, "action", "audit");
 467
 468                         if (entry->action != UNKNOWN)
 469                                 result = -EINVAL;
 470
 471                         entry->action = AUDIT;
 472                         break;
 473                 case Opt_func:
 474                         ima_log_string(ab, "func", args[0].from);
 475
 476                         if (entry->func)
 477                                 result = -EINVAL;
 478
 479                         if (strcmp(args[0].from, "FILE_CHECK") == 0)
 480                                 entry->func = FILE_CHECK;
 481                         /* PATH_CHECK is for backwards compat */
 482                         else if (strcmp(args[0].from, "PATH_CHECK") == 0)
 483                                 entry->func = FILE_CHECK;
 484                         else if (strcmp(args[0].from, "MODULE_CHECK") == 0)
 485                                 entry->func = MODULE_CHECK;
 486                         else if ((strcmp(args[0].from, "FILE_MMAP") == 0)
 487                                 || (strcmp(args[0].from, "MMAP_CHECK") == 0))
 488                                 entry->func = MMAP_CHECK;
 489                         else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
 490                                 entry->func = BPRM_CHECK;
 491                         else
 492                                 result = -EINVAL;
 493                         if (!result)
 494                                 entry->flags |= IMA_FUNC;
 495                         break;
 496                 case Opt_mask:
 497                         ima_log_string(ab, "mask", args[0].from);
 498
 499                         if (entry->mask)
 500                                 result = -EINVAL;
 501
 502                         if ((strcmp(args[0].from, "MAY_EXEC")) == 0)
 503                                 entry->mask = MAY_EXEC;
 504                         else if (strcmp(args[0].from, "MAY_WRITE") == 0)
 505                                 entry->mask = MAY_WRITE;
 506                         else if (strcmp(args[0].from, "MAY_READ") == 0)
 507                                 entry->mask = MAY_READ;
 508                         else if (strcmp(args[0].from, "MAY_APPEND") == 0)
 509                                 entry->mask = MAY_APPEND;
 510                         else
 511                                 result = -EINVAL;
 512                         if (!result)
 513                                 entry->flags |= IMA_MASK;
 514                         break;
 515                 case Opt_fsmagic:
 516                         ima_log_string(ab, "fsmagic", args[0].from);
 517
 518                         if (entry->fsmagic) {
 519                                 result = -EINVAL;
 520                                 break;
 521                         }
 522
 523                         result = strict_strtoul(args[0].from, 16,
 524                                                 &entry->fsmagic);
 525                         if (!result)
 526                                 entry->flags |= IMA_FSMAGIC;
 527                         break;
 528                 case Opt_fsuuid:
 529                         ima_log_string(ab, "fsuuid", args[0].from);
 530
 531                         if (memchr_inv(entry->fsuuid, 0x00,
 532                                        sizeof(entry->fsuuid))) {
 533                                 result = -EINVAL;
 534                                 break;
 535                         }
 536
 537                         result = blk_part_pack_uuid(args[0].from,
 538                                                     entry->fsuuid);
 539                         if (!result)
 540                                 entry->flags |= IMA_FSUUID;
 541                         break;
 542                 case Opt_uid:
 543                         ima_log_string(ab, "uid", args[0].from);
 544
 545                         if (uid_valid(entry->uid)) {
 546                                 result = -EINVAL;
 547                                 break;
 548                         }
 549
 550                         result = strict_strtoul(args[0].from, 10, &lnum);
 551                         if (!result) {
 552                                 entry->uid = make_kuid(current_user_ns(), (uid_t)lnum);
 553                                 if (!uid_valid(entry->uid) || (((uid_t)lnum) != lnum))
 554                                         result = -EINVAL;
 555                                 else
 556                                         entry->flags |= IMA_UID;
 557                         }
 558                         break;
 559                 case Opt_fowner:
 560                         ima_log_string(ab, "fowner", args[0].from);
 561
 562                         if (uid_valid(entry->fowner)) {
 563                                 result = -EINVAL;
 564                                 break;
 565                         }
 566
 567                         result = strict_strtoul(args[0].from, 10, &lnum);
 568                         if (!result) {
 569                                 entry->fowner = make_kuid(current_user_ns(), (uid_t)lnum);
 570                                 if (!uid_valid(entry->fowner) || (((uid_t)lnum) != lnum))
 571                                         result = -EINVAL;
 572                                 else
 573                                         entry->flags |= IMA_FOWNER;
 574                         }
 575                         break;
 576                 case Opt_obj_user:
 577                         ima_log_string(ab, "obj_user", args[0].from);
 578                         result = ima_lsm_rule_init(entry, args,
 579                                                    LSM_OBJ_USER,
 580                                                    AUDIT_OBJ_USER);
 581                         break;
 582                 case Opt_obj_role:
 583                         ima_log_string(ab, "obj_role", args[0].from);
 584                         result = ima_lsm_rule_init(entry, args,
 585                                                    LSM_OBJ_ROLE,
 586                                                    AUDIT_OBJ_ROLE);
 587                         break;
 588                 case Opt_obj_type:
 589                         ima_log_string(ab, "obj_type", args[0].from);
 590                         result = ima_lsm_rule_init(entry, args,
 591                                                    LSM_OBJ_TYPE,
 592                                                    AUDIT_OBJ_TYPE);
 593                         break;
 594                 case Opt_subj_user:
 595                         ima_log_string(ab, "subj_user", args[0].from);
 596                         result = ima_lsm_rule_init(entry, args,
 597                                                    LSM_SUBJ_USER,
 598                                                    AUDIT_SUBJ_USER);
 599                         break;
 600                 case Opt_subj_role:
 601                         ima_log_string(ab, "subj_role", args[0].from);
 602                         result = ima_lsm_rule_init(entry, args,
 603                                                    LSM_SUBJ_ROLE,
 604                                                    AUDIT_SUBJ_ROLE);
 605                         break;
 606                 case Opt_subj_type:
 607                         ima_log_string(ab, "subj_type", args[0].from);
 608                         result = ima_lsm_rule_init(entry, args,
 609                                                    LSM_SUBJ_TYPE,
 610                                                    AUDIT_SUBJ_TYPE);
 611                         break;
 612                 case Opt_appraise_type:
 613                         if (entry->action != APPRAISE) {
 614                                 result = -EINVAL;
 615                                 break;
 616                         }
 617
 618                         ima_log_string(ab, "appraise_type", args[0].from);
 619                         if ((strcmp(args[0].from, "imasig")) == 0)
 620                                 entry->flags |= IMA_DIGSIG_REQUIRED;
 621                         else
 622                                 result = -EINVAL;
 623                         break;
 624                 case Opt_err:
 625                         ima_log_string(ab, "UNKNOWN", p);
 626                         result = -EINVAL;
 627                         break;
 628                 }
 629         }
 630         if (!result && (entry->action == UNKNOWN))
 631                 result = -EINVAL;
 632         else if (entry->func == MODULE_CHECK)
 633                 ima_appraise |= IMA_APPRAISE_MODULES;
 634         audit_log_format(ab, "res=%d", !result);
 635         audit_log_end(ab);
 636         return result;
 637 }
 638
 639 /**
 640  * ima_parse_add_rule - add a rule to ima_policy_rules
 641  * @rule - ima measurement policy rule
 642  *
 643  * Uses a mutex to protect the policy list from multiple concurrent writers.
 644  * Returns the length of the rule parsed, an error code on failure
 645  */
 646 ssize_t ima_parse_add_rule(char *rule)
 647 {
 648         const char *op = "update_policy";
 649         char *p;
 650         struct ima_rule_entry *entry;
 651         ssize_t result, len;
 652         int audit_info = 0;
 653
 654         /* Prevent installed policy from changing */
 655         if (ima_rules != &ima_default_rules) {
 656                 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
 657                                     NULL, op, "already exists",
 658                                     -EACCES, audit_info);
 659                 return -EACCES;
 660         }
 661
 662         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 663         if (!entry) {
 664                 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
 665                                     NULL, op, "-ENOMEM", -ENOMEM, audit_info);
 666                 return -ENOMEM;
 667         }
 668
 669         INIT_LIST_HEAD(&entry->list);
 670
 671         p = strsep(&rule, "\n");
 672         len = strlen(p) + 1;
 673
 674         if (*p == '#') {
 675                 kfree(entry);
 676                 return len;
 677         }
 678
 679         result = ima_parse_rule(p, entry);
 680         if (result) {
 681                 kfree(entry);
 682                 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
 683                                     NULL, op, "invalid policy", result,
 684                                     audit_info);
 685                 return result;
 686         }
 687
 688         mutex_lock(&ima_rules_mutex);
 689         list_add_tail(&entry->list, &ima_policy_rules);
 690         mutex_unlock(&ima_rules_mutex);
 691
 692         return len;
 693 }
 694
 695 /* ima_delete_rules called to cleanup invalid policy */
 696 void ima_delete_rules(void)
 697 {
 698         struct ima_rule_entry *entry, *tmp;
 699         int i;
 700
 701         mutex_lock(&ima_rules_mutex);
 702         list_for_each_entry_safe(entry, tmp, &ima_policy_rules, list) {
 703                 for (i = 0; i < MAX_LSM_RULES; i++)
 704                         kfree(entry->lsm[i].args_p);
 705
 706                 list_del(&entry->list);
 707                 kfree(entry);
 708         }
 709         mutex_unlock(&ima_rules_mutex);
 710 }