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/fs.h>
  16 #include <linux/security.h>
  17 #include <linux/magic.h>
  18 #include <linux/parser.h>
  19 #include <linux/slab.h>
  20 #include <linux/rculist.h>
  21 #include <linux/genhd.h>
  22 #include <linux/seq_file.h>
  23
  24 #include "ima.h"
  25
  26 /* flags definitions */
  27 #define IMA_FUNC        0x0001
  28 #define IMA_MASK        0x0002
  29 #define IMA_FSMAGIC     0x0004
  30 #define IMA_UID         0x0008
  31 #define IMA_FOWNER      0x0010
  32 #define IMA_FSUUID      0x0020
  33 #define IMA_INMASK      0x0040
  34 #define IMA_EUID        0x0080
  35 #define IMA_PCR         0x0100
  36
  37 #define UNKNOWN         0
  38 #define MEASURE         0x0001  /* same as IMA_MEASURE */
  39 #define DONT_MEASURE    0x0002
  40 #define APPRAISE        0x0004  /* same as IMA_APPRAISE */
  41 #define DONT_APPRAISE   0x0008
  42 #define AUDIT           0x0040
  43
  44 #define INVALID_PCR(a) (((a) < 0) || \
  45         (a) >= (FIELD_SIZEOF(struct integrity_iint_cache, measured_pcrs) * 8))
  46
  47 int ima_policy_flag;
  48 static int temp_ima_appraise;
  49
  50 #define MAX_LSM_RULES 6
  51 enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
  52         LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
  53 };
  54
  55 enum policy_types { ORIGINAL_TCB = 1, DEFAULT_TCB };
  56
  57 struct ima_rule_entry {
  58         struct list_head list;
  59         int action;
  60         unsigned int flags;
  61         enum ima_hooks func;
  62         int mask;
  63         unsigned long fsmagic;
  64         uuid_t fsuuid;
  65         kuid_t uid;
  66         kuid_t fowner;
  67         bool (*uid_op)(kuid_t, kuid_t);    /* Handlers for operators       */
  68         bool (*fowner_op)(kuid_t, kuid_t); /* uid_eq(), uid_gt(), uid_lt() */
  69         int pcr;
  70         struct {
  71                 void *rule;     /* LSM file metadata specific */
  72                 void *args_p;   /* audit value */
  73                 int type;       /* audit type */
  74         } lsm[MAX_LSM_RULES];
  75 };
  76
  77 /*
  78  * Without LSM specific knowledge, the default policy can only be
  79  * written in terms of .action, .func, .mask, .fsmagic, .uid, and .fowner
  80  */
  81
  82 /*
  83  * The minimum rule set to allow for full TCB coverage.  Measures all files
  84  * opened or mmap for exec and everything read by root.  Dangerous because
  85  * normal users can easily run the machine out of memory simply building
  86  * and running executables.
  87  */
  88 static struct ima_rule_entry dont_measure_rules[] __ro_after_init = {
  89         {.action = DONT_MEASURE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
  90         {.action = DONT_MEASURE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
  91         {.action = DONT_MEASURE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
  92         {.action = DONT_MEASURE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
  93         {.action = DONT_MEASURE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
  94         {.action = DONT_MEASURE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
  95         {.action = DONT_MEASURE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
  96         {.action = DONT_MEASURE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
  97         {.action = DONT_MEASURE, .fsmagic = CGROUP_SUPER_MAGIC,
  98          .flags = IMA_FSMAGIC},
  99         {.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC}
 100 };
 101
 102 static struct ima_rule_entry original_measurement_rules[] __ro_after_init = {
 103         {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
 104          .flags = IMA_FUNC | IMA_MASK},
 105         {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
 106          .flags = IMA_FUNC | IMA_MASK},
 107         {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
 108          .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
 109          .flags = IMA_FUNC | IMA_MASK | IMA_UID},
 110         {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
 111         {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
 112 };
 113
 114 static struct ima_rule_entry default_measurement_rules[] __ro_after_init = {
 115         {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
 116          .flags = IMA_FUNC | IMA_MASK},
 117         {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
 118          .flags = IMA_FUNC | IMA_MASK},
 119         {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
 120          .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
 121          .flags = IMA_FUNC | IMA_INMASK | IMA_EUID},
 122         {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
 123          .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
 124          .flags = IMA_FUNC | IMA_INMASK | IMA_UID},
 125         {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
 126         {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
 127         {.action = MEASURE, .func = POLICY_CHECK, .flags = IMA_FUNC},
 128 };
 129
 130 static struct ima_rule_entry default_appraise_rules[] __ro_after_init = {
 131         {.action = DONT_APPRAISE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 132         {.action = DONT_APPRAISE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
 133         {.action = DONT_APPRAISE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
 134         {.action = DONT_APPRAISE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
 135         {.action = DONT_APPRAISE, .fsmagic = RAMFS_MAGIC, .flags = IMA_FSMAGIC},
 136         {.action = DONT_APPRAISE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 137         {.action = DONT_APPRAISE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
 138         {.action = DONT_APPRAISE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
 139         {.action = DONT_APPRAISE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
 140         {.action = DONT_APPRAISE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
 141         {.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 142 #ifdef CONFIG_IMA_WRITE_POLICY
 143         {.action = APPRAISE, .func = POLICY_CHECK,
 144         .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 145 #endif
 146 #ifndef CONFIG_IMA_APPRAISE_SIGNED_INIT
 147         {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &uid_eq,
 148          .flags = IMA_FOWNER},
 149 #else
 150         /* force signature */
 151         {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &uid_eq,
 152          .flags = IMA_FOWNER | IMA_DIGSIG_REQUIRED},
 153 #endif
 154 };
 155
 156 static LIST_HEAD(ima_default_rules);
 157 static LIST_HEAD(ima_policy_rules);
 158 static LIST_HEAD(ima_temp_rules);
 159 static struct list_head *ima_rules;
 160
 161 static int ima_policy __initdata;
 162
 163 static int __init default_measure_policy_setup(char *str)
 164 {
 165         if (ima_policy)
 166                 return 1;
 167
 168         ima_policy = ORIGINAL_TCB;
 169         return 1;
 170 }
 171 __setup("ima_tcb", default_measure_policy_setup);
 172
 173 static int __init policy_setup(char *str)
 174 {
 175         if (ima_policy)
 176                 return 1;
 177
 178         if (strcmp(str, "tcb") == 0)
 179                 ima_policy = DEFAULT_TCB;
 180
 181         return 1;
 182 }
 183 __setup("ima_policy=", policy_setup);
 184
 185 static bool ima_use_appraise_tcb __initdata;
 186 static int __init default_appraise_policy_setup(char *str)
 187 {
 188         ima_use_appraise_tcb = 1;
 189         return 1;
 190 }
 191 __setup("ima_appraise_tcb", default_appraise_policy_setup);
 192
 193 /*
 194  * The LSM policy can be reloaded, leaving the IMA LSM based rules referring
 195  * to the old, stale LSM policy.  Update the IMA LSM based rules to reflect
 196  * the reloaded LSM policy.  We assume the rules still exist; and BUG_ON() if
 197  * they don't.
 198  */
 199 static void ima_lsm_update_rules(void)
 200 {
 201         struct ima_rule_entry *entry;
 202         int result;
 203         int i;
 204
 205         list_for_each_entry(entry, &ima_policy_rules, list) {
 206                 for (i = 0; i < MAX_LSM_RULES; i++) {
 207                         if (!entry->lsm[i].rule)
 208                                 continue;
 209                         result = security_filter_rule_init(entry->lsm[i].type,
 210                                                            Audit_equal,
 211                                                            entry->lsm[i].args_p,
 212                                                            &entry->lsm[i].rule);
 213                         BUG_ON(!entry->lsm[i].rule);
 214                 }
 215         }
 216 }
 217
 218 /**
 219  * ima_match_rules - determine whether an inode matches the measure rule.
 220  * @rule: a pointer to a rule
 221  * @inode: a pointer to an inode
 222  * @func: LIM hook identifier
 223  * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
 224  *
 225  * Returns true on rule match, false on failure.
 226  */
 227 static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
 228                             enum ima_hooks func, int mask)
 229 {
 230         struct task_struct *tsk = current;
 231         const struct cred *cred = current_cred();
 232         int i;
 233
 234         if ((rule->flags & IMA_FUNC) &&
 235             (rule->func != func && func != POST_SETATTR))
 236                 return false;
 237         if ((rule->flags & IMA_MASK) &&
 238             (rule->mask != mask && func != POST_SETATTR))
 239                 return false;
 240         if ((rule->flags & IMA_INMASK) &&
 241             (!(rule->mask & mask) && func != POST_SETATTR))
 242                 return false;
 243         if ((rule->flags & IMA_FSMAGIC)
 244             && rule->fsmagic != inode->i_sb->s_magic)
 245                 return false;
 246         if ((rule->flags & IMA_FSUUID) &&
 247             !uuid_equal(&rule->fsuuid, &inode->i_sb->s_uuid))
 248                 return false;
 249         if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid))
 250                 return false;
 251         if (rule->flags & IMA_EUID) {
 252                 if (has_capability_noaudit(current, CAP_SETUID)) {
 253                         if (!rule->uid_op(cred->euid, rule->uid)
 254                             && !rule->uid_op(cred->suid, rule->uid)
 255                             && !rule->uid_op(cred->uid, rule->uid))
 256                                 return false;
 257                 } else if (!rule->uid_op(cred->euid, rule->uid))
 258                         return false;
 259         }
 260
 261         if ((rule->flags & IMA_FOWNER) &&
 262             !rule->fowner_op(inode->i_uid, rule->fowner))
 263                 return false;
 264         for (i = 0; i < MAX_LSM_RULES; i++) {
 265                 int rc = 0;
 266                 u32 osid, sid;
 267                 int retried = 0;
 268
 269                 if (!rule->lsm[i].rule)
 270                         continue;
 271 retry:
 272                 switch (i) {
 273                 case LSM_OBJ_USER:
 274                 case LSM_OBJ_ROLE:
 275                 case LSM_OBJ_TYPE:
 276                         security_inode_getsecid(inode, &osid);
 277                         rc = security_filter_rule_match(osid,
 278                                                         rule->lsm[i].type,
 279                                                         Audit_equal,
 280                                                         rule->lsm[i].rule,
 281                                                         NULL);
 282                         break;
 283                 case LSM_SUBJ_USER:
 284                 case LSM_SUBJ_ROLE:
 285                 case LSM_SUBJ_TYPE:
 286                         security_task_getsecid(tsk, &sid);
 287                         rc = security_filter_rule_match(sid,
 288                                                         rule->lsm[i].type,
 289                                                         Audit_equal,
 290                                                         rule->lsm[i].rule,
 291                                                         NULL);
 292                 default:
 293                         break;
 294                 }
 295                 if ((rc < 0) && (!retried)) {
 296                         retried = 1;
 297                         ima_lsm_update_rules();
 298                         goto retry;
 299                 }
 300                 if (!rc)
 301                         return false;
 302         }
 303         return true;
 304 }
 305
 306 /*
 307  * In addition to knowing that we need to appraise the file in general,
 308  * we need to differentiate between calling hooks, for hook specific rules.
 309  */
 310 static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func)
 311 {
 312         if (!(rule->flags & IMA_FUNC))
 313                 return IMA_FILE_APPRAISE;
 314
 315         switch (func) {
 316         case MMAP_CHECK:
 317                 return IMA_MMAP_APPRAISE;
 318         case BPRM_CHECK:
 319                 return IMA_BPRM_APPRAISE;
 320         case FILE_CHECK:
 321         case POST_SETATTR:
 322                 return IMA_FILE_APPRAISE;
 323         case MODULE_CHECK ... MAX_CHECK - 1:
 324         default:
 325                 return IMA_READ_APPRAISE;
 326         }
 327 }
 328
 329 /**
 330  * ima_match_policy - decision based on LSM and other conditions
 331  * @inode: pointer to an inode for which the policy decision is being made
 332  * @func: IMA hook identifier
 333  * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
 334  * @pcr: set the pcr to extend
 335  *
 336  * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
 337  * conditions.
 338  *
 339  * Since the IMA policy may be updated multiple times we need to lock the
 340  * list when walking it.  Reads are many orders of magnitude more numerous
 341  * than writes so ima_match_policy() is classical RCU candidate.
 342  */
 343 int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
 344                      int flags, int *pcr)
 345 {
 346         struct ima_rule_entry *entry;
 347         int action = 0, actmask = flags | (flags << 1);
 348
 349         rcu_read_lock();
 350         list_for_each_entry_rcu(entry, ima_rules, list) {
 351
 352                 if (!(entry->action & actmask))
 353                         continue;
 354
 355                 if (!ima_match_rules(entry, inode, func, mask))
 356                         continue;
 357
 358                 action |= entry->flags & IMA_ACTION_FLAGS;
 359
 360                 action |= entry->action & IMA_DO_MASK;
 361                 if (entry->action & IMA_APPRAISE)
 362                         action |= get_subaction(entry, func);
 363
 364                 if (entry->action & IMA_DO_MASK)
 365                         actmask &= ~(entry->action | entry->action << 1);
 366                 else
 367                         actmask &= ~(entry->action | entry->action >> 1);
 368
 369                 if ((pcr) && (entry->flags & IMA_PCR))
 370                         *pcr = entry->pcr;
 371
 372                 if (!actmask)
 373                         break;
 374         }
 375         rcu_read_unlock();
 376
 377         return action;
 378 }
 379
 380 /*
 381  * Initialize the ima_policy_flag variable based on the currently
 382  * loaded policy.  Based on this flag, the decision to short circuit
 383  * out of a function or not call the function in the first place
 384  * can be made earlier.
 385  */
 386 void ima_update_policy_flag(void)
 387 {
 388         struct ima_rule_entry *entry;
 389
 390         list_for_each_entry(entry, ima_rules, list) {
 391                 if (entry->action & IMA_DO_MASK)
 392                         ima_policy_flag |= entry->action;
 393         }
 394
 395         ima_appraise |= temp_ima_appraise;
 396         if (!ima_appraise)
 397                 ima_policy_flag &= ~IMA_APPRAISE;
 398 }
 399
 400 /**
 401  * ima_init_policy - initialize the default measure rules.
 402  *
 403  * ima_rules points to either the ima_default_rules or the
 404  * the new ima_policy_rules.
 405  */
 406 void __init ima_init_policy(void)
 407 {
 408         int i, measure_entries, appraise_entries;
 409
 410         /* if !ima_policy set entries = 0 so we load NO default rules */
 411         measure_entries = ima_policy ? ARRAY_SIZE(dont_measure_rules) : 0;
 412         appraise_entries = ima_use_appraise_tcb ?
 413                          ARRAY_SIZE(default_appraise_rules) : 0;
 414
 415         for (i = 0; i < measure_entries; i++)
 416                 list_add_tail(&dont_measure_rules[i].list, &ima_default_rules);
 417
 418         switch (ima_policy) {
 419         case ORIGINAL_TCB:
 420                 for (i = 0; i < ARRAY_SIZE(original_measurement_rules); i++)
 421                         list_add_tail(&original_measurement_rules[i].list,
 422                                       &ima_default_rules);
 423                 break;
 424         case DEFAULT_TCB:
 425                 for (i = 0; i < ARRAY_SIZE(default_measurement_rules); i++)
 426                         list_add_tail(&default_measurement_rules[i].list,
 427                                       &ima_default_rules);
 428         default:
 429                 break;
 430         }
 431
 432         for (i = 0; i < appraise_entries; i++) {
 433                 list_add_tail(&default_appraise_rules[i].list,
 434                               &ima_default_rules);
 435                 if (default_appraise_rules[i].func == POLICY_CHECK)
 436                         temp_ima_appraise |= IMA_APPRAISE_POLICY;
 437         }
 438
 439         ima_rules = &ima_default_rules;
 440         ima_update_policy_flag();
 441 }
 442
 443 /* Make sure we have a valid policy, at least containing some rules. */
 444 int ima_check_policy(void)
 445 {
 446         if (list_empty(&ima_temp_rules))
 447                 return -EINVAL;
 448         return 0;
 449 }
 450
 451 /**
 452  * ima_update_policy - update default_rules with new measure rules
 453  *
 454  * Called on file .release to update the default rules with a complete new
 455  * policy.  What we do here is to splice ima_policy_rules and ima_temp_rules so
 456  * they make a queue.  The policy may be updated multiple times and this is the
 457  * RCU updater.
 458  *
 459  * Policy rules are never deleted so ima_policy_flag gets zeroed only once when
 460  * we switch from the default policy to user defined.
 461  */
 462 void ima_update_policy(void)
 463 {
 464         struct list_head *first, *last, *policy;
 465
 466         /* append current policy with the new rules */
 467         first = (&ima_temp_rules)->next;
 468         last = (&ima_temp_rules)->prev;
 469         policy = &ima_policy_rules;
 470
 471         synchronize_rcu();
 472
 473         last->next = policy;
 474         rcu_assign_pointer(list_next_rcu(policy->prev), first);
 475         first->prev = policy->prev;
 476         policy->prev = last;
 477
 478         /* prepare for the next policy rules addition */
 479         INIT_LIST_HEAD(&ima_temp_rules);
 480
 481         if (ima_rules != policy) {
 482                 ima_policy_flag = 0;
 483                 ima_rules = policy;
 484         }
 485         ima_update_policy_flag();
 486 }
 487
 488 enum {
 489         Opt_err = -1,
 490         Opt_measure = 1, Opt_dont_measure,
 491         Opt_appraise, Opt_dont_appraise,
 492         Opt_audit,
 493         Opt_obj_user, Opt_obj_role, Opt_obj_type,
 494         Opt_subj_user, Opt_subj_role, Opt_subj_type,
 495         Opt_func, Opt_mask, Opt_fsmagic,
 496         Opt_fsuuid, Opt_uid_eq, Opt_euid_eq, Opt_fowner_eq,
 497         Opt_uid_gt, Opt_euid_gt, Opt_fowner_gt,
 498         Opt_uid_lt, Opt_euid_lt, Opt_fowner_lt,
 499         Opt_appraise_type, Opt_permit_directio,
 500         Opt_pcr
 501 };
 502
 503 static match_table_t policy_tokens = {
 504         {Opt_measure, "measure"},
 505         {Opt_dont_measure, "dont_measure"},
 506         {Opt_appraise, "appraise"},
 507         {Opt_dont_appraise, "dont_appraise"},
 508         {Opt_audit, "audit"},
 509         {Opt_obj_user, "obj_user=%s"},
 510         {Opt_obj_role, "obj_role=%s"},
 511         {Opt_obj_type, "obj_type=%s"},
 512         {Opt_subj_user, "subj_user=%s"},
 513         {Opt_subj_role, "subj_role=%s"},
 514         {Opt_subj_type, "subj_type=%s"},
 515         {Opt_func, "func=%s"},
 516         {Opt_mask, "mask=%s"},
 517         {Opt_fsmagic, "fsmagic=%s"},
 518         {Opt_fsuuid, "fsuuid=%s"},
 519         {Opt_uid_eq, "uid=%s"},
 520         {Opt_euid_eq, "euid=%s"},
 521         {Opt_fowner_eq, "fowner=%s"},
 522         {Opt_uid_gt, "uid>%s"},
 523         {Opt_euid_gt, "euid>%s"},
 524         {Opt_fowner_gt, "fowner>%s"},
 525         {Opt_uid_lt, "uid<%s"},
 526         {Opt_euid_lt, "euid<%s"},
 527         {Opt_fowner_lt, "fowner<%s"},
 528         {Opt_appraise_type, "appraise_type=%s"},
 529         {Opt_permit_directio, "permit_directio"},
 530         {Opt_pcr, "pcr=%s"},
 531         {Opt_err, NULL}
 532 };
 533
 534 static int ima_lsm_rule_init(struct ima_rule_entry *entry,
 535                              substring_t *args, int lsm_rule, int audit_type)
 536 {
 537         int result;
 538
 539         if (entry->lsm[lsm_rule].rule)
 540                 return -EINVAL;
 541
 542         entry->lsm[lsm_rule].args_p = match_strdup(args);
 543         if (!entry->lsm[lsm_rule].args_p)
 544                 return -ENOMEM;
 545
 546         entry->lsm[lsm_rule].type = audit_type;
 547         result = security_filter_rule_init(entry->lsm[lsm_rule].type,
 548                                            Audit_equal,
 549                                            entry->lsm[lsm_rule].args_p,
 550                                            &entry->lsm[lsm_rule].rule);
 551         if (!entry->lsm[lsm_rule].rule) {
 552                 kfree(entry->lsm[lsm_rule].args_p);
 553                 return -EINVAL;
 554         }
 555
 556         return result;
 557 }
 558
 559 static void ima_log_string_op(struct audit_buffer *ab, char *key, char *value,
 560                               bool (*rule_operator)(kuid_t, kuid_t))
 561 {
 562         if (rule_operator == &uid_gt)
 563                 audit_log_format(ab, "%s>", key);
 564         else if (rule_operator == &uid_lt)
 565                 audit_log_format(ab, "%s<", key);
 566         else
 567                 audit_log_format(ab, "%s=", key);
 568         audit_log_untrustedstring(ab, value);
 569         audit_log_format(ab, " ");
 570 }
 571 static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
 572 {
 573         ima_log_string_op(ab, key, value, NULL);
 574 }
 575
 576 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 577 {
 578         struct audit_buffer *ab;
 579         char *from;
 580         char *p;
 581         bool uid_token;
 582         int result = 0;
 583
 584         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);
 585
 586         entry->uid = INVALID_UID;
 587         entry->fowner = INVALID_UID;
 588         entry->uid_op = &uid_eq;
 589         entry->fowner_op = &uid_eq;
 590         entry->action = UNKNOWN;
 591         while ((p = strsep(&rule, " \t")) != NULL) {
 592                 substring_t args[MAX_OPT_ARGS];
 593                 int token;
 594                 unsigned long lnum;
 595
 596                 if (result < 0)
 597                         break;
 598                 if ((*p == '\0') || (*p == ' ') || (*p == '\t'))
 599                         continue;
 600                 token = match_token(p, policy_tokens, args);
 601                 switch (token) {
 602                 case Opt_measure:
 603                         ima_log_string(ab, "action", "measure");
 604
 605                         if (entry->action != UNKNOWN)
 606                                 result = -EINVAL;
 607
 608                         entry->action = MEASURE;
 609                         break;
 610                 case Opt_dont_measure:
 611                         ima_log_string(ab, "action", "dont_measure");
 612
 613                         if (entry->action != UNKNOWN)
 614                                 result = -EINVAL;
 615
 616                         entry->action = DONT_MEASURE;
 617                         break;
 618                 case Opt_appraise:
 619                         ima_log_string(ab, "action", "appraise");
 620
 621                         if (entry->action != UNKNOWN)
 622                                 result = -EINVAL;
 623
 624                         entry->action = APPRAISE;
 625                         break;
 626                 case Opt_dont_appraise:
 627                         ima_log_string(ab, "action", "dont_appraise");
 628
 629                         if (entry->action != UNKNOWN)
 630                                 result = -EINVAL;
 631
 632                         entry->action = DONT_APPRAISE;
 633                         break;
 634                 case Opt_audit:
 635                         ima_log_string(ab, "action", "audit");
 636
 637                         if (entry->action != UNKNOWN)
 638                                 result = -EINVAL;
 639
 640                         entry->action = AUDIT;
 641                         break;
 642                 case Opt_func:
 643                         ima_log_string(ab, "func", args[0].from);
 644
 645                         if (entry->func)
 646                                 result = -EINVAL;
 647
 648                         if (strcmp(args[0].from, "FILE_CHECK") == 0)
 649                                 entry->func = FILE_CHECK;
 650                         /* PATH_CHECK is for backwards compat */
 651                         else if (strcmp(args[0].from, "PATH_CHECK") == 0)
 652                                 entry->func = FILE_CHECK;
 653                         else if (strcmp(args[0].from, "MODULE_CHECK") == 0)
 654                                 entry->func = MODULE_CHECK;
 655                         else if (strcmp(args[0].from, "FIRMWARE_CHECK") == 0)
 656                                 entry->func = FIRMWARE_CHECK;
 657                         else if ((strcmp(args[0].from, "FILE_MMAP") == 0)
 658                                 || (strcmp(args[0].from, "MMAP_CHECK") == 0))
 659                                 entry->func = MMAP_CHECK;
 660                         else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
 661                                 entry->func = BPRM_CHECK;
 662                         else if (strcmp(args[0].from, "KEXEC_KERNEL_CHECK") ==
 663                                  0)
 664                                 entry->func = KEXEC_KERNEL_CHECK;
 665                         else if (strcmp(args[0].from, "KEXEC_INITRAMFS_CHECK")
 666                                  == 0)
 667                                 entry->func = KEXEC_INITRAMFS_CHECK;
 668                         else if (strcmp(args[0].from, "POLICY_CHECK") == 0)
 669                                 entry->func = POLICY_CHECK;
 670                         else
 671                                 result = -EINVAL;
 672                         if (!result)
 673                                 entry->flags |= IMA_FUNC;
 674                         break;
 675                 case Opt_mask:
 676                         ima_log_string(ab, "mask", args[0].from);
 677
 678                         if (entry->mask)
 679                                 result = -EINVAL;
 680
 681                         from = args[0].from;
 682                         if (*from == '^')
 683                                 from++;
 684
 685                         if ((strcmp(from, "MAY_EXEC")) == 0)
 686                                 entry->mask = MAY_EXEC;
 687                         else if (strcmp(from, "MAY_WRITE") == 0)
 688                                 entry->mask = MAY_WRITE;
 689                         else if (strcmp(from, "MAY_READ") == 0)
 690                                 entry->mask = MAY_READ;
 691                         else if (strcmp(from, "MAY_APPEND") == 0)
 692                                 entry->mask = MAY_APPEND;
 693                         else
 694                                 result = -EINVAL;
 695                         if (!result)
 696                                 entry->flags |= (*args[0].from == '^')
 697                                      ? IMA_INMASK : IMA_MASK;
 698                         break;
 699                 case Opt_fsmagic:
 700                         ima_log_string(ab, "fsmagic", args[0].from);
 701
 702                         if (entry->fsmagic) {
 703                                 result = -EINVAL;
 704                                 break;
 705                         }
 706
 707                         result = kstrtoul(args[0].from, 16, &entry->fsmagic);
 708                         if (!result)
 709                                 entry->flags |= IMA_FSMAGIC;
 710                         break;
 711                 case Opt_fsuuid:
 712                         ima_log_string(ab, "fsuuid", args[0].from);
 713
 714                         if (uuid_is_null(&entry->fsuuid)) {
 715                                 result = -EINVAL;
 716                                 break;
 717                         }
 718
 719                         result = uuid_parse(args[0].from, &entry->fsuuid);
 720                         if (!result)
 721                                 entry->flags |= IMA_FSUUID;
 722                         break;
 723                 case Opt_uid_gt:
 724                 case Opt_euid_gt:
 725                         entry->uid_op = &uid_gt;
 726                 case Opt_uid_lt:
 727                 case Opt_euid_lt:
 728                         if ((token == Opt_uid_lt) || (token == Opt_euid_lt))
 729                                 entry->uid_op = &uid_lt;
 730                 case Opt_uid_eq:
 731                 case Opt_euid_eq:
 732                         uid_token = (token == Opt_uid_eq) ||
 733                                     (token == Opt_uid_gt) ||
 734                                     (token == Opt_uid_lt);
 735
 736                         ima_log_string_op(ab, uid_token ? "uid" : "euid",
 737                                           args[0].from, entry->uid_op);
 738
 739                         if (uid_valid(entry->uid)) {
 740                                 result = -EINVAL;
 741                                 break;
 742                         }
 743
 744                         result = kstrtoul(args[0].from, 10, &lnum);
 745                         if (!result) {
 746                                 entry->uid = make_kuid(current_user_ns(),
 747                                                        (uid_t) lnum);
 748                                 if (!uid_valid(entry->uid) ||
 749                                     (uid_t)lnum != lnum)
 750                                         result = -EINVAL;
 751                                 else
 752                                         entry->flags |= uid_token
 753                                             ? IMA_UID : IMA_EUID;
 754                         }
 755                         break;
 756                 case Opt_fowner_gt:
 757                         entry->fowner_op = &uid_gt;
 758                 case Opt_fowner_lt:
 759                         if (token == Opt_fowner_lt)
 760                                 entry->fowner_op = &uid_lt;
 761                 case Opt_fowner_eq:
 762                         ima_log_string_op(ab, "fowner", args[0].from,
 763                                           entry->fowner_op);
 764
 765                         if (uid_valid(entry->fowner)) {
 766                                 result = -EINVAL;
 767                                 break;
 768                         }
 769
 770                         result = kstrtoul(args[0].from, 10, &lnum);
 771                         if (!result) {
 772                                 entry->fowner = make_kuid(current_user_ns(), (uid_t)lnum);
 773                                 if (!uid_valid(entry->fowner) || (((uid_t)lnum) != lnum))
 774                                         result = -EINVAL;
 775                                 else
 776                                         entry->flags |= IMA_FOWNER;
 777                         }
 778                         break;
 779                 case Opt_obj_user:
 780                         ima_log_string(ab, "obj_user", args[0].from);
 781                         result = ima_lsm_rule_init(entry, args,
 782                                                    LSM_OBJ_USER,
 783                                                    AUDIT_OBJ_USER);
 784                         break;
 785                 case Opt_obj_role:
 786                         ima_log_string(ab, "obj_role", args[0].from);
 787                         result = ima_lsm_rule_init(entry, args,
 788                                                    LSM_OBJ_ROLE,
 789                                                    AUDIT_OBJ_ROLE);
 790                         break;
 791                 case Opt_obj_type:
 792                         ima_log_string(ab, "obj_type", args[0].from);
 793                         result = ima_lsm_rule_init(entry, args,
 794                                                    LSM_OBJ_TYPE,
 795                                                    AUDIT_OBJ_TYPE);
 796                         break;
 797                 case Opt_subj_user:
 798                         ima_log_string(ab, "subj_user", args[0].from);
 799                         result = ima_lsm_rule_init(entry, args,
 800                                                    LSM_SUBJ_USER,
 801                                                    AUDIT_SUBJ_USER);
 802                         break;
 803                 case Opt_subj_role:
 804                         ima_log_string(ab, "subj_role", args[0].from);
 805                         result = ima_lsm_rule_init(entry, args,
 806                                                    LSM_SUBJ_ROLE,
 807                                                    AUDIT_SUBJ_ROLE);
 808                         break;
 809                 case Opt_subj_type:
 810                         ima_log_string(ab, "subj_type", args[0].from);
 811                         result = ima_lsm_rule_init(entry, args,
 812                                                    LSM_SUBJ_TYPE,
 813                                                    AUDIT_SUBJ_TYPE);
 814                         break;
 815                 case Opt_appraise_type:
 816                         if (entry->action != APPRAISE) {
 817                                 result = -EINVAL;
 818                                 break;
 819                         }
 820
 821                         ima_log_string(ab, "appraise_type", args[0].from);
 822                         if ((strcmp(args[0].from, "imasig")) == 0)
 823                                 entry->flags |= IMA_DIGSIG_REQUIRED;
 824                         else
 825                                 result = -EINVAL;
 826                         break;
 827                 case Opt_permit_directio:
 828                         entry->flags |= IMA_PERMIT_DIRECTIO;
 829                         break;
 830                 case Opt_pcr:
 831                         if (entry->action != MEASURE) {
 832                                 result = -EINVAL;
 833                                 break;
 834                         }
 835                         ima_log_string(ab, "pcr", args[0].from);
 836
 837                         result = kstrtoint(args[0].from, 10, &entry->pcr);
 838                         if (result || INVALID_PCR(entry->pcr))
 839                                 result = -EINVAL;
 840                         else
 841                                 entry->flags |= IMA_PCR;
 842
 843                         break;
 844                 case Opt_err:
 845                         ima_log_string(ab, "UNKNOWN", p);
 846                         result = -EINVAL;
 847                         break;
 848                 }
 849         }
 850         if (!result && (entry->action == UNKNOWN))
 851                 result = -EINVAL;
 852         else if (entry->func == MODULE_CHECK)
 853                 temp_ima_appraise |= IMA_APPRAISE_MODULES;
 854         else if (entry->func == FIRMWARE_CHECK)
 855                 temp_ima_appraise |= IMA_APPRAISE_FIRMWARE;
 856         else if (entry->func == POLICY_CHECK)
 857                 temp_ima_appraise |= IMA_APPRAISE_POLICY;
 858         audit_log_format(ab, "res=%d", !result);
 859         audit_log_end(ab);
 860         return result;
 861 }
 862
 863 /**
 864  * ima_parse_add_rule - add a rule to ima_policy_rules
 865  * @rule - ima measurement policy rule
 866  *
 867  * Avoid locking by allowing just one writer at a time in ima_write_policy()
 868  * Returns the length of the rule parsed, an error code on failure
 869  */
 870 ssize_t ima_parse_add_rule(char *rule)
 871 {
 872         static const char op[] = "update_policy";
 873         char *p;
 874         struct ima_rule_entry *entry;
 875         ssize_t result, len;
 876         int audit_info = 0;
 877
 878         p = strsep(&rule, "\n");
 879         len = strlen(p) + 1;
 880         p += strspn(p, " \t");
 881
 882         if (*p == '#' || *p == '\0')
 883                 return len;
 884
 885         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 886         if (!entry) {
 887                 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
 888                                     NULL, op, "-ENOMEM", -ENOMEM, audit_info);
 889                 return -ENOMEM;
 890         }
 891
 892         INIT_LIST_HEAD(&entry->list);
 893
 894         result = ima_parse_rule(p, entry);
 895         if (result) {
 896                 kfree(entry);
 897                 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
 898                                     NULL, op, "invalid-policy", result,
 899                                     audit_info);
 900                 return result;
 901         }
 902
 903         list_add_tail(&entry->list, &ima_temp_rules);
 904
 905         return len;
 906 }
 907
 908 /**
 909  * ima_delete_rules() called to cleanup invalid in-flight policy.
 910  * We don't need locking as we operate on the temp list, which is
 911  * different from the active one.  There is also only one user of
 912  * ima_delete_rules() at a time.
 913  */
 914 void ima_delete_rules(void)
 915 {
 916         struct ima_rule_entry *entry, *tmp;
 917         int i;
 918
 919         temp_ima_appraise = 0;
 920         list_for_each_entry_safe(entry, tmp, &ima_temp_rules, list) {
 921                 for (i = 0; i < MAX_LSM_RULES; i++)
 922                         kfree(entry->lsm[i].args_p);
 923
 924                 list_del(&entry->list);
 925                 kfree(entry);
 926         }
 927 }
 928
 929 #ifdef  CONFIG_IMA_READ_POLICY
 930 enum {
 931         mask_exec = 0, mask_write, mask_read, mask_append
 932 };
 933
 934 static char *mask_tokens[] = {
 935         "MAY_EXEC",
 936         "MAY_WRITE",
 937         "MAY_READ",
 938         "MAY_APPEND"
 939 };
 940
 941 enum {
 942         func_file = 0, func_mmap, func_bprm,
 943         func_module, func_firmware, func_post,
 944         func_kexec_kernel, func_kexec_initramfs,
 945         func_policy
 946 };
 947
 948 static char *func_tokens[] = {
 949         "FILE_CHECK",
 950         "MMAP_CHECK",
 951         "BPRM_CHECK",
 952         "MODULE_CHECK",
 953         "FIRMWARE_CHECK",
 954         "POST_SETATTR",
 955         "KEXEC_KERNEL_CHECK",
 956         "KEXEC_INITRAMFS_CHECK",
 957         "POLICY_CHECK"
 958 };
 959
 960 void *ima_policy_start(struct seq_file *m, loff_t *pos)
 961 {
 962         loff_t l = *pos;
 963         struct ima_rule_entry *entry;
 964
 965         rcu_read_lock();
 966         list_for_each_entry_rcu(entry, ima_rules, list) {
 967                 if (!l--) {
 968                         rcu_read_unlock();
 969                         return entry;
 970                 }
 971         }
 972         rcu_read_unlock();
 973         return NULL;
 974 }
 975
 976 void *ima_policy_next(struct seq_file *m, void *v, loff_t *pos)
 977 {
 978         struct ima_rule_entry *entry = v;
 979
 980         rcu_read_lock();
 981         entry = list_entry_rcu(entry->list.next, struct ima_rule_entry, list);
 982         rcu_read_unlock();
 983         (*pos)++;
 984
 985         return (&entry->list == ima_rules) ? NULL : entry;
 986 }
 987
 988 void ima_policy_stop(struct seq_file *m, void *v)
 989 {
 990 }
 991
 992 #define pt(token)       policy_tokens[token + Opt_err].pattern
 993 #define mt(token)       mask_tokens[token]
 994 #define ft(token)       func_tokens[token]
 995
 996 /*
 997  * policy_func_show - display the ima_hooks policy rule
 998  */
 999 static void policy_func_show(struct seq_file *m, enum ima_hooks func)
1000 {
1001         char tbuf[64] = {0,};
1002
1003         switch (func) {
1004         case FILE_CHECK:
1005                 seq_printf(m, pt(Opt_func), ft(func_file));
1006                 break;
1007         case MMAP_CHECK:
1008                 seq_printf(m, pt(Opt_func), ft(func_mmap));
1009                 break;
1010         case BPRM_CHECK:
1011                 seq_printf(m, pt(Opt_func), ft(func_bprm));
1012                 break;
1013         case MODULE_CHECK:
1014                 seq_printf(m, pt(Opt_func), ft(func_module));
1015                 break;
1016         case FIRMWARE_CHECK:
1017                 seq_printf(m, pt(Opt_func), ft(func_firmware));
1018                 break;
1019         case POST_SETATTR:
1020                 seq_printf(m, pt(Opt_func), ft(func_post));
1021                 break;
1022         case KEXEC_KERNEL_CHECK:
1023                 seq_printf(m, pt(Opt_func), ft(func_kexec_kernel));
1024                 break;
1025         case KEXEC_INITRAMFS_CHECK:
1026                 seq_printf(m, pt(Opt_func), ft(func_kexec_initramfs));
1027                 break;
1028         case POLICY_CHECK:
1029                 seq_printf(m, pt(Opt_func), ft(func_policy));
1030                 break;
1031         default:
1032                 snprintf(tbuf, sizeof(tbuf), "%d", func);
1033                 seq_printf(m, pt(Opt_func), tbuf);
1034                 break;
1035         }
1036         seq_puts(m, " ");
1037 }
1038
1039 int ima_policy_show(struct seq_file *m, void *v)
1040 {
1041         struct ima_rule_entry *entry = v;
1042         int i;
1043         char tbuf[64] = {0,};
1044
1045         rcu_read_lock();
1046
1047         if (entry->action & MEASURE)
1048                 seq_puts(m, pt(Opt_measure));
1049         if (entry->action & DONT_MEASURE)
1050                 seq_puts(m, pt(Opt_dont_measure));
1051         if (entry->action & APPRAISE)
1052                 seq_puts(m, pt(Opt_appraise));
1053         if (entry->action & DONT_APPRAISE)
1054                 seq_puts(m, pt(Opt_dont_appraise));
1055         if (entry->action & AUDIT)
1056                 seq_puts(m, pt(Opt_audit));
1057
1058         seq_puts(m, " ");
1059
1060         if (entry->flags & IMA_FUNC)
1061                 policy_func_show(m, entry->func);
1062
1063         if (entry->flags & IMA_MASK) {
1064                 if (entry->mask & MAY_EXEC)
1065                         seq_printf(m, pt(Opt_mask), mt(mask_exec));
1066                 if (entry->mask & MAY_WRITE)
1067                         seq_printf(m, pt(Opt_mask), mt(mask_write));
1068                 if (entry->mask & MAY_READ)
1069                         seq_printf(m, pt(Opt_mask), mt(mask_read));
1070                 if (entry->mask & MAY_APPEND)
1071                         seq_printf(m, pt(Opt_mask), mt(mask_append));
1072                 seq_puts(m, " ");
1073         }
1074
1075         if (entry->flags & IMA_FSMAGIC) {
1076                 snprintf(tbuf, sizeof(tbuf), "0x%lx", entry->fsmagic);
1077                 seq_printf(m, pt(Opt_fsmagic), tbuf);
1078                 seq_puts(m, " ");
1079         }
1080
1081         if (entry->flags & IMA_PCR) {
1082                 snprintf(tbuf, sizeof(tbuf), "%d", entry->pcr);
1083                 seq_printf(m, pt(Opt_pcr), tbuf);
1084                 seq_puts(m, " ");
1085         }
1086
1087         if (entry->flags & IMA_FSUUID) {
1088                 seq_printf(m, "fsuuid=%pU", &entry->fsuuid);
1089                 seq_puts(m, " ");
1090         }
1091
1092         if (entry->flags & IMA_UID) {
1093                 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
1094                 if (entry->uid_op == &uid_gt)
1095                         seq_printf(m, pt(Opt_uid_gt), tbuf);
1096                 else if (entry->uid_op == &uid_lt)
1097                         seq_printf(m, pt(Opt_uid_lt), tbuf);
1098                 else
1099                         seq_printf(m, pt(Opt_uid_eq), tbuf);
1100                 seq_puts(m, " ");
1101         }
1102
1103         if (entry->flags & IMA_EUID) {
1104                 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
1105                 if (entry->uid_op == &uid_gt)
1106                         seq_printf(m, pt(Opt_euid_gt), tbuf);
1107                 else if (entry->uid_op == &uid_lt)
1108                         seq_printf(m, pt(Opt_euid_lt), tbuf);
1109                 else
1110                         seq_printf(m, pt(Opt_euid_eq), tbuf);
1111                 seq_puts(m, " ");
1112         }
1113
1114         if (entry->flags & IMA_FOWNER) {
1115                 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->fowner));
1116                 if (entry->fowner_op == &uid_gt)
1117                         seq_printf(m, pt(Opt_fowner_gt), tbuf);
1118                 else if (entry->fowner_op == &uid_lt)
1119                         seq_printf(m, pt(Opt_fowner_lt), tbuf);
1120                 else
1121                         seq_printf(m, pt(Opt_fowner_eq), tbuf);
1122                 seq_puts(m, " ");
1123         }
1124
1125         for (i = 0; i < MAX_LSM_RULES; i++) {
1126                 if (entry->lsm[i].rule) {
1127                         switch (i) {
1128                         case LSM_OBJ_USER:
1129                                 seq_printf(m, pt(Opt_obj_user),
1130                                            (char *)entry->lsm[i].args_p);
1131                                 break;
1132                         case LSM_OBJ_ROLE:
1133                                 seq_printf(m, pt(Opt_obj_role),
1134                                            (char *)entry->lsm[i].args_p);
1135                                 break;
1136                         case LSM_OBJ_TYPE:
1137                                 seq_printf(m, pt(Opt_obj_type),
1138                                            (char *)entry->lsm[i].args_p);
1139                                 break;
1140                         case LSM_SUBJ_USER:
1141                                 seq_printf(m, pt(Opt_subj_user),
1142                                            (char *)entry->lsm[i].args_p);
1143                                 break;
1144                         case LSM_SUBJ_ROLE:
1145                                 seq_printf(m, pt(Opt_subj_role),
1146                                            (char *)entry->lsm[i].args_p);
1147                                 break;
1148                         case LSM_SUBJ_TYPE:
1149                                 seq_printf(m, pt(Opt_subj_type),
1150                                            (char *)entry->lsm[i].args_p);
1151                                 break;
1152                         }
1153                 }
1154         }
1155         if (entry->flags & IMA_DIGSIG_REQUIRED)
1156                 seq_puts(m, "appraise_type=imasig ");
1157         if (entry->flags & IMA_PERMIT_DIRECTIO)
1158                 seq_puts(m, "permit_directio ");
1159         rcu_read_unlock();
1160         seq_puts(m, "\n");
1161         return 0;
1162 }
1163 #endif  /* CONFIG_IMA_READ_POLICY */