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 = CGROUP2_SUPER_MAGIC,
 100          .flags = IMA_FSMAGIC},
 101         {.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC}
 102 };
 103
 104 static struct ima_rule_entry original_measurement_rules[] __ro_after_init = {
 105         {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
 106          .flags = IMA_FUNC | IMA_MASK},
 107         {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
 108          .flags = IMA_FUNC | IMA_MASK},
 109         {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
 110          .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
 111          .flags = IMA_FUNC | IMA_MASK | IMA_UID},
 112         {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
 113         {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
 114 };
 115
 116 static struct ima_rule_entry default_measurement_rules[] __ro_after_init = {
 117         {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
 118          .flags = IMA_FUNC | IMA_MASK},
 119         {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
 120          .flags = IMA_FUNC | IMA_MASK},
 121         {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
 122          .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
 123          .flags = IMA_FUNC | IMA_INMASK | IMA_EUID},
 124         {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
 125          .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
 126          .flags = IMA_FUNC | IMA_INMASK | IMA_UID},
 127         {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
 128         {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
 129         {.action = MEASURE, .func = POLICY_CHECK, .flags = IMA_FUNC},
 130 };
 131
 132 static struct ima_rule_entry default_appraise_rules[] __ro_after_init = {
 133         {.action = DONT_APPRAISE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 134         {.action = DONT_APPRAISE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
 135         {.action = DONT_APPRAISE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
 136         {.action = DONT_APPRAISE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
 137         {.action = DONT_APPRAISE, .fsmagic = RAMFS_MAGIC, .flags = IMA_FSMAGIC},
 138         {.action = DONT_APPRAISE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 139         {.action = DONT_APPRAISE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
 140         {.action = DONT_APPRAISE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
 141         {.action = DONT_APPRAISE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
 142         {.action = DONT_APPRAISE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
 143         {.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 144         {.action = DONT_APPRAISE, .fsmagic = CGROUP2_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 145 #ifdef CONFIG_IMA_WRITE_POLICY
 146         {.action = APPRAISE, .func = POLICY_CHECK,
 147         .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 148 #endif
 149 #ifndef CONFIG_IMA_APPRAISE_SIGNED_INIT
 150         {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &uid_eq,
 151          .flags = IMA_FOWNER},
 152 #else
 153         /* force signature */
 154         {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &uid_eq,
 155          .flags = IMA_FOWNER | IMA_DIGSIG_REQUIRED},
 156 #endif
 157 };
 158
 159 static struct ima_rule_entry secure_boot_rules[] __ro_after_init = {
 160         {.action = APPRAISE, .func = MODULE_CHECK,
 161          .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 162         {.action = APPRAISE, .func = FIRMWARE_CHECK,
 163          .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 164         {.action = APPRAISE, .func = KEXEC_KERNEL_CHECK,
 165          .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 166         {.action = APPRAISE, .func = POLICY_CHECK,
 167          .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 168 };
 169
 170 static LIST_HEAD(ima_default_rules);
 171 static LIST_HEAD(ima_policy_rules);
 172 static LIST_HEAD(ima_temp_rules);
 173 static struct list_head *ima_rules = &ima_default_rules;
 174
 175 static int ima_policy __initdata;
 176
 177 static int __init default_measure_policy_setup(char *str)
 178 {
 179         if (ima_policy)
 180                 return 1;
 181
 182         ima_policy = ORIGINAL_TCB;
 183         return 1;
 184 }
 185 __setup("ima_tcb", default_measure_policy_setup);
 186
 187 static bool ima_use_appraise_tcb __initdata;
 188 static bool ima_use_secure_boot __initdata;
 189 static int __init policy_setup(char *str)
 190 {
 191         char *p;
 192
 193         while ((p = strsep(&str, " |\n")) != NULL) {
 194                 if (*p == ' ')
 195                         continue;
 196                 if ((strcmp(p, "tcb") == 0) && !ima_policy)
 197                         ima_policy = DEFAULT_TCB;
 198                 else if (strcmp(p, "appraise_tcb") == 0)
 199                         ima_use_appraise_tcb = 1;
 200                 else if (strcmp(p, "secure_boot") == 0)
 201                         ima_use_secure_boot = 1;
 202         }
 203
 204         return 1;
 205 }
 206 __setup("ima_policy=", policy_setup);
 207
 208 static int __init default_appraise_policy_setup(char *str)
 209 {
 210         ima_use_appraise_tcb = 1;
 211         return 1;
 212 }
 213 __setup("ima_appraise_tcb", default_appraise_policy_setup);
 214
 215 /*
 216  * The LSM policy can be reloaded, leaving the IMA LSM based rules referring
 217  * to the old, stale LSM policy.  Update the IMA LSM based rules to reflect
 218  * the reloaded LSM policy.  We assume the rules still exist; and BUG_ON() if
 219  * they don't.
 220  */
 221 static void ima_lsm_update_rules(void)
 222 {
 223         struct ima_rule_entry *entry;
 224         int result;
 225         int i;
 226
 227         list_for_each_entry(entry, &ima_policy_rules, list) {
 228                 for (i = 0; i < MAX_LSM_RULES; i++) {
 229                         if (!entry->lsm[i].rule)
 230                                 continue;
 231                         result = security_filter_rule_init(entry->lsm[i].type,
 232                                                            Audit_equal,
 233                                                            entry->lsm[i].args_p,
 234                                                            &entry->lsm[i].rule);
 235                         BUG_ON(!entry->lsm[i].rule);
 236                 }
 237         }
 238 }
 239
 240 /**
 241  * ima_match_rules - determine whether an inode matches the measure rule.
 242  * @rule: a pointer to a rule
 243  * @inode: a pointer to an inode
 244  * @func: LIM hook identifier
 245  * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
 246  *
 247  * Returns true on rule match, false on failure.
 248  */
 249 static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
 250                             enum ima_hooks func, int mask)
 251 {
 252         struct task_struct *tsk = current;
 253         const struct cred *cred = current_cred();
 254         int i;
 255
 256         if ((rule->flags & IMA_FUNC) &&
 257             (rule->func != func && func != POST_SETATTR))
 258                 return false;
 259         if ((rule->flags & IMA_MASK) &&
 260             (rule->mask != mask && func != POST_SETATTR))
 261                 return false;
 262         if ((rule->flags & IMA_INMASK) &&
 263             (!(rule->mask & mask) && func != POST_SETATTR))
 264                 return false;
 265         if ((rule->flags & IMA_FSMAGIC)
 266             && rule->fsmagic != inode->i_sb->s_magic)
 267                 return false;
 268         if ((rule->flags & IMA_FSUUID) &&
 269             !uuid_equal(&rule->fsuuid, &inode->i_sb->s_uuid))
 270                 return false;
 271         if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid))
 272                 return false;
 273         if (rule->flags & IMA_EUID) {
 274                 if (has_capability_noaudit(current, CAP_SETUID)) {
 275                         if (!rule->uid_op(cred->euid, rule->uid)
 276                             && !rule->uid_op(cred->suid, rule->uid)
 277                             && !rule->uid_op(cred->uid, rule->uid))
 278                                 return false;
 279                 } else if (!rule->uid_op(cred->euid, rule->uid))
 280                         return false;
 281         }
 282
 283         if ((rule->flags & IMA_FOWNER) &&
 284             !rule->fowner_op(inode->i_uid, rule->fowner))
 285                 return false;
 286         for (i = 0; i < MAX_LSM_RULES; i++) {
 287                 int rc = 0;
 288                 u32 osid, sid;
 289                 int retried = 0;
 290
 291                 if (!rule->lsm[i].rule)
 292                         continue;
 293 retry:
 294                 switch (i) {
 295                 case LSM_OBJ_USER:
 296                 case LSM_OBJ_ROLE:
 297                 case LSM_OBJ_TYPE:
 298                         security_inode_getsecid(inode, &osid);
 299                         rc = security_filter_rule_match(osid,
 300                                                         rule->lsm[i].type,
 301                                                         Audit_equal,
 302                                                         rule->lsm[i].rule,
 303                                                         NULL);
 304                         break;
 305                 case LSM_SUBJ_USER:
 306                 case LSM_SUBJ_ROLE:
 307                 case LSM_SUBJ_TYPE:
 308                         security_task_getsecid(tsk, &sid);
 309                         rc = security_filter_rule_match(sid,
 310                                                         rule->lsm[i].type,
 311                                                         Audit_equal,
 312                                                         rule->lsm[i].rule,
 313                                                         NULL);
 314                 default:
 315                         break;
 316                 }
 317                 if ((rc < 0) && (!retried)) {
 318                         retried = 1;
 319                         ima_lsm_update_rules();
 320                         goto retry;
 321                 }
 322                 if (!rc)
 323                         return false;
 324         }
 325         return true;
 326 }
 327
 328 /*
 329  * In addition to knowing that we need to appraise the file in general,
 330  * we need to differentiate between calling hooks, for hook specific rules.
 331  */
 332 static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func)
 333 {
 334         if (!(rule->flags & IMA_FUNC))
 335                 return IMA_FILE_APPRAISE;
 336
 337         switch (func) {
 338         case MMAP_CHECK:
 339                 return IMA_MMAP_APPRAISE;
 340         case BPRM_CHECK:
 341                 return IMA_BPRM_APPRAISE;
 342         case FILE_CHECK:
 343         case POST_SETATTR:
 344                 return IMA_FILE_APPRAISE;
 345         case MODULE_CHECK ... MAX_CHECK - 1:
 346         default:
 347                 return IMA_READ_APPRAISE;
 348         }
 349 }
 350
 351 /**
 352  * ima_match_policy - decision based on LSM and other conditions
 353  * @inode: pointer to an inode for which the policy decision is being made
 354  * @func: IMA hook identifier
 355  * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
 356  * @pcr: set the pcr to extend
 357  *
 358  * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
 359  * conditions.
 360  *
 361  * Since the IMA policy may be updated multiple times we need to lock the
 362  * list when walking it.  Reads are many orders of magnitude more numerous
 363  * than writes so ima_match_policy() is classical RCU candidate.
 364  */
 365 int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
 366                      int flags, int *pcr)
 367 {
 368         struct ima_rule_entry *entry;
 369         int action = 0, actmask = flags | (flags << 1);
 370
 371         rcu_read_lock();
 372         list_for_each_entry_rcu(entry, ima_rules, list) {
 373
 374                 if (!(entry->action & actmask))
 375                         continue;
 376
 377                 if (!ima_match_rules(entry, inode, func, mask))
 378                         continue;
 379
 380                 action |= entry->flags & IMA_ACTION_FLAGS;
 381
 382                 action |= entry->action & IMA_DO_MASK;
 383                 if (entry->action & IMA_APPRAISE)
 384                         action |= get_subaction(entry, func);
 385
 386                 if (entry->action & IMA_DO_MASK)
 387                         actmask &= ~(entry->action | entry->action << 1);
 388                 else
 389                         actmask &= ~(entry->action | entry->action >> 1);
 390
 391                 if ((pcr) && (entry->flags & IMA_PCR))
 392                         *pcr = entry->pcr;
 393
 394                 if (!actmask)
 395                         break;
 396         }
 397         rcu_read_unlock();
 398
 399         return action;
 400 }
 401
 402 /*
 403  * Initialize the ima_policy_flag variable based on the currently
 404  * loaded policy.  Based on this flag, the decision to short circuit
 405  * out of a function or not call the function in the first place
 406  * can be made earlier.
 407  */
 408 void ima_update_policy_flag(void)
 409 {
 410         struct ima_rule_entry *entry;
 411
 412         list_for_each_entry(entry, ima_rules, list) {
 413                 if (entry->action & IMA_DO_MASK)
 414                         ima_policy_flag |= entry->action;
 415         }
 416
 417         ima_appraise |= temp_ima_appraise;
 418         if (!ima_appraise)
 419                 ima_policy_flag &= ~IMA_APPRAISE;
 420 }
 421
 422 /**
 423  * ima_init_policy - initialize the default measure rules.
 424  *
 425  * ima_rules points to either the ima_default_rules or the
 426  * the new ima_policy_rules.
 427  */
 428 void __init ima_init_policy(void)
 429 {
 430         int i, measure_entries, appraise_entries, secure_boot_entries;
 431
 432         /* if !ima_policy set entries = 0 so we load NO default rules */
 433         measure_entries = ima_policy ? ARRAY_SIZE(dont_measure_rules) : 0;
 434         appraise_entries = ima_use_appraise_tcb ?
 435                          ARRAY_SIZE(default_appraise_rules) : 0;
 436         secure_boot_entries = ima_use_secure_boot ?
 437                         ARRAY_SIZE(secure_boot_rules) : 0;
 438
 439         for (i = 0; i < measure_entries; i++)
 440                 list_add_tail(&dont_measure_rules[i].list, &ima_default_rules);
 441
 442         switch (ima_policy) {
 443         case ORIGINAL_TCB:
 444                 for (i = 0; i < ARRAY_SIZE(original_measurement_rules); i++)
 445                         list_add_tail(&original_measurement_rules[i].list,
 446                                       &ima_default_rules);
 447                 break;
 448         case DEFAULT_TCB:
 449                 for (i = 0; i < ARRAY_SIZE(default_measurement_rules); i++)
 450                         list_add_tail(&default_measurement_rules[i].list,
 451                                       &ima_default_rules);
 452         default:
 453                 break;
 454         }
 455
 456         /*
 457          * Insert the appraise rules requiring file signatures, prior to
 458          * any other appraise rules.
 459          */
 460         for (i = 0; i < secure_boot_entries; i++)
 461                 list_add_tail(&secure_boot_rules[i].list,
 462                               &ima_default_rules);
 463
 464         for (i = 0; i < appraise_entries; i++) {
 465                 list_add_tail(&default_appraise_rules[i].list,
 466                               &ima_default_rules);
 467                 if (default_appraise_rules[i].func == POLICY_CHECK)
 468                         temp_ima_appraise |= IMA_APPRAISE_POLICY;
 469         }
 470
 471         ima_update_policy_flag();
 472 }
 473
 474 /* Make sure we have a valid policy, at least containing some rules. */
 475 int ima_check_policy(void)
 476 {
 477         if (list_empty(&ima_temp_rules))
 478                 return -EINVAL;
 479         return 0;
 480 }
 481
 482 /**
 483  * ima_update_policy - update default_rules with new measure rules
 484  *
 485  * Called on file .release to update the default rules with a complete new
 486  * policy.  What we do here is to splice ima_policy_rules and ima_temp_rules so
 487  * they make a queue.  The policy may be updated multiple times and this is the
 488  * RCU updater.
 489  *
 490  * Policy rules are never deleted so ima_policy_flag gets zeroed only once when
 491  * we switch from the default policy to user defined.
 492  */
 493 void ima_update_policy(void)
 494 {
 495         struct list_head *first, *last, *policy;
 496
 497         /* append current policy with the new rules */
 498         first = (&ima_temp_rules)->next;
 499         last = (&ima_temp_rules)->prev;
 500         policy = &ima_policy_rules;
 501
 502         synchronize_rcu();
 503
 504         last->next = policy;
 505         rcu_assign_pointer(list_next_rcu(policy->prev), first);
 506         first->prev = policy->prev;
 507         policy->prev = last;
 508
 509         /* prepare for the next policy rules addition */
 510         INIT_LIST_HEAD(&ima_temp_rules);
 511
 512         if (ima_rules != policy) {
 513                 ima_policy_flag = 0;
 514                 ima_rules = policy;
 515         }
 516         ima_update_policy_flag();
 517 }
 518
 519 enum {
 520         Opt_err = -1,
 521         Opt_measure = 1, Opt_dont_measure,
 522         Opt_appraise, Opt_dont_appraise,
 523         Opt_audit,
 524         Opt_obj_user, Opt_obj_role, Opt_obj_type,
 525         Opt_subj_user, Opt_subj_role, Opt_subj_type,
 526         Opt_func, Opt_mask, Opt_fsmagic,
 527         Opt_fsuuid, Opt_uid_eq, Opt_euid_eq, Opt_fowner_eq,
 528         Opt_uid_gt, Opt_euid_gt, Opt_fowner_gt,
 529         Opt_uid_lt, Opt_euid_lt, Opt_fowner_lt,
 530         Opt_appraise_type, Opt_permit_directio,
 531         Opt_pcr
 532 };
 533
 534 static match_table_t policy_tokens = {
 535         {Opt_measure, "measure"},
 536         {Opt_dont_measure, "dont_measure"},
 537         {Opt_appraise, "appraise"},
 538         {Opt_dont_appraise, "dont_appraise"},
 539         {Opt_audit, "audit"},
 540         {Opt_obj_user, "obj_user=%s"},
 541         {Opt_obj_role, "obj_role=%s"},
 542         {Opt_obj_type, "obj_type=%s"},
 543         {Opt_subj_user, "subj_user=%s"},
 544         {Opt_subj_role, "subj_role=%s"},
 545         {Opt_subj_type, "subj_type=%s"},
 546         {Opt_func, "func=%s"},
 547         {Opt_mask, "mask=%s"},
 548         {Opt_fsmagic, "fsmagic=%s"},
 549         {Opt_fsuuid, "fsuuid=%s"},
 550         {Opt_uid_eq, "uid=%s"},
 551         {Opt_euid_eq, "euid=%s"},
 552         {Opt_fowner_eq, "fowner=%s"},
 553         {Opt_uid_gt, "uid>%s"},
 554         {Opt_euid_gt, "euid>%s"},
 555         {Opt_fowner_gt, "fowner>%s"},
 556         {Opt_uid_lt, "uid<%s"},
 557         {Opt_euid_lt, "euid<%s"},
 558         {Opt_fowner_lt, "fowner<%s"},
 559         {Opt_appraise_type, "appraise_type=%s"},
 560         {Opt_permit_directio, "permit_directio"},
 561         {Opt_pcr, "pcr=%s"},
 562         {Opt_err, NULL}
 563 };
 564
 565 static int ima_lsm_rule_init(struct ima_rule_entry *entry,
 566                              substring_t *args, int lsm_rule, int audit_type)
 567 {
 568         int result;
 569
 570         if (entry->lsm[lsm_rule].rule)
 571                 return -EINVAL;
 572
 573         entry->lsm[lsm_rule].args_p = match_strdup(args);
 574         if (!entry->lsm[lsm_rule].args_p)
 575                 return -ENOMEM;
 576
 577         entry->lsm[lsm_rule].type = audit_type;
 578         result = security_filter_rule_init(entry->lsm[lsm_rule].type,
 579                                            Audit_equal,
 580                                            entry->lsm[lsm_rule].args_p,
 581                                            &entry->lsm[lsm_rule].rule);
 582         if (!entry->lsm[lsm_rule].rule) {
 583                 kfree(entry->lsm[lsm_rule].args_p);
 584                 return -EINVAL;
 585         }
 586
 587         return result;
 588 }
 589
 590 static void ima_log_string_op(struct audit_buffer *ab, char *key, char *value,
 591                               bool (*rule_operator)(kuid_t, kuid_t))
 592 {
 593         if (rule_operator == &uid_gt)
 594                 audit_log_format(ab, "%s>", key);
 595         else if (rule_operator == &uid_lt)
 596                 audit_log_format(ab, "%s<", key);
 597         else
 598                 audit_log_format(ab, "%s=", key);
 599         audit_log_untrustedstring(ab, value);
 600         audit_log_format(ab, " ");
 601 }
 602 static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
 603 {
 604         ima_log_string_op(ab, key, value, NULL);
 605 }
 606
 607 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 608 {
 609         struct audit_buffer *ab;
 610         char *from;
 611         char *p;
 612         bool uid_token;
 613         int result = 0;
 614
 615         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);
 616
 617         entry->uid = INVALID_UID;
 618         entry->fowner = INVALID_UID;
 619         entry->uid_op = &uid_eq;
 620         entry->fowner_op = &uid_eq;
 621         entry->action = UNKNOWN;
 622         while ((p = strsep(&rule, " \t")) != NULL) {
 623                 substring_t args[MAX_OPT_ARGS];
 624                 int token;
 625                 unsigned long lnum;
 626
 627                 if (result < 0)
 628                         break;
 629                 if ((*p == '\0') || (*p == ' ') || (*p == '\t'))
 630                         continue;
 631                 token = match_token(p, policy_tokens, args);
 632                 switch (token) {
 633                 case Opt_measure:
 634                         ima_log_string(ab, "action", "measure");
 635
 636                         if (entry->action != UNKNOWN)
 637                                 result = -EINVAL;
 638
 639                         entry->action = MEASURE;
 640                         break;
 641                 case Opt_dont_measure:
 642                         ima_log_string(ab, "action", "dont_measure");
 643
 644                         if (entry->action != UNKNOWN)
 645                                 result = -EINVAL;
 646
 647                         entry->action = DONT_MEASURE;
 648                         break;
 649                 case Opt_appraise:
 650                         ima_log_string(ab, "action", "appraise");
 651
 652                         if (entry->action != UNKNOWN)
 653                                 result = -EINVAL;
 654
 655                         entry->action = APPRAISE;
 656                         break;
 657                 case Opt_dont_appraise:
 658                         ima_log_string(ab, "action", "dont_appraise");
 659
 660                         if (entry->action != UNKNOWN)
 661                                 result = -EINVAL;
 662
 663                         entry->action = DONT_APPRAISE;
 664                         break;
 665                 case Opt_audit:
 666                         ima_log_string(ab, "action", "audit");
 667
 668                         if (entry->action != UNKNOWN)
 669                                 result = -EINVAL;
 670
 671                         entry->action = AUDIT;
 672                         break;
 673                 case Opt_func:
 674                         ima_log_string(ab, "func", args[0].from);
 675
 676                         if (entry->func)
 677                                 result = -EINVAL;
 678
 679                         if (strcmp(args[0].from, "FILE_CHECK") == 0)
 680                                 entry->func = FILE_CHECK;
 681                         /* PATH_CHECK is for backwards compat */
 682                         else if (strcmp(args[0].from, "PATH_CHECK") == 0)
 683                                 entry->func = FILE_CHECK;
 684                         else if (strcmp(args[0].from, "MODULE_CHECK") == 0)
 685                                 entry->func = MODULE_CHECK;
 686                         else if (strcmp(args[0].from, "FIRMWARE_CHECK") == 0)
 687                                 entry->func = FIRMWARE_CHECK;
 688                         else if ((strcmp(args[0].from, "FILE_MMAP") == 0)
 689                                 || (strcmp(args[0].from, "MMAP_CHECK") == 0))
 690                                 entry->func = MMAP_CHECK;
 691                         else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
 692                                 entry->func = BPRM_CHECK;
 693                         else if (strcmp(args[0].from, "KEXEC_KERNEL_CHECK") ==
 694                                  0)
 695                                 entry->func = KEXEC_KERNEL_CHECK;
 696                         else if (strcmp(args[0].from, "KEXEC_INITRAMFS_CHECK")
 697                                  == 0)
 698                                 entry->func = KEXEC_INITRAMFS_CHECK;
 699                         else if (strcmp(args[0].from, "POLICY_CHECK") == 0)
 700                                 entry->func = POLICY_CHECK;
 701                         else
 702                                 result = -EINVAL;
 703                         if (!result)
 704                                 entry->flags |= IMA_FUNC;
 705                         break;
 706                 case Opt_mask:
 707                         ima_log_string(ab, "mask", args[0].from);
 708
 709                         if (entry->mask)
 710                                 result = -EINVAL;
 711
 712                         from = args[0].from;
 713                         if (*from == '^')
 714                                 from++;
 715
 716                         if ((strcmp(from, "MAY_EXEC")) == 0)
 717                                 entry->mask = MAY_EXEC;
 718                         else if (strcmp(from, "MAY_WRITE") == 0)
 719                                 entry->mask = MAY_WRITE;
 720                         else if (strcmp(from, "MAY_READ") == 0)
 721                                 entry->mask = MAY_READ;
 722                         else if (strcmp(from, "MAY_APPEND") == 0)
 723                                 entry->mask = MAY_APPEND;
 724                         else
 725                                 result = -EINVAL;
 726                         if (!result)
 727                                 entry->flags |= (*args[0].from == '^')
 728                                      ? IMA_INMASK : IMA_MASK;
 729                         break;
 730                 case Opt_fsmagic:
 731                         ima_log_string(ab, "fsmagic", args[0].from);
 732
 733                         if (entry->fsmagic) {
 734                                 result = -EINVAL;
 735                                 break;
 736                         }
 737
 738                         result = kstrtoul(args[0].from, 16, &entry->fsmagic);
 739                         if (!result)
 740                                 entry->flags |= IMA_FSMAGIC;
 741                         break;
 742                 case Opt_fsuuid:
 743                         ima_log_string(ab, "fsuuid", args[0].from);
 744
 745                         if (!uuid_is_null(&entry->fsuuid)) {
 746                                 result = -EINVAL;
 747                                 break;
 748                         }
 749
 750                         result = uuid_parse(args[0].from, &entry->fsuuid);
 751                         if (!result)
 752                                 entry->flags |= IMA_FSUUID;
 753                         break;
 754                 case Opt_uid_gt:
 755                 case Opt_euid_gt:
 756                         entry->uid_op = &uid_gt;
 757                 case Opt_uid_lt:
 758                 case Opt_euid_lt:
 759                         if ((token == Opt_uid_lt) || (token == Opt_euid_lt))
 760                                 entry->uid_op = &uid_lt;
 761                 case Opt_uid_eq:
 762                 case Opt_euid_eq:
 763                         uid_token = (token == Opt_uid_eq) ||
 764                                     (token == Opt_uid_gt) ||
 765                                     (token == Opt_uid_lt);
 766
 767                         ima_log_string_op(ab, uid_token ? "uid" : "euid",
 768                                           args[0].from, entry->uid_op);
 769
 770                         if (uid_valid(entry->uid)) {
 771                                 result = -EINVAL;
 772                                 break;
 773                         }
 774
 775                         result = kstrtoul(args[0].from, 10, &lnum);
 776                         if (!result) {
 777                                 entry->uid = make_kuid(current_user_ns(),
 778                                                        (uid_t) lnum);
 779                                 if (!uid_valid(entry->uid) ||
 780                                     (uid_t)lnum != lnum)
 781                                         result = -EINVAL;
 782                                 else
 783                                         entry->flags |= uid_token
 784                                             ? IMA_UID : IMA_EUID;
 785                         }
 786                         break;
 787                 case Opt_fowner_gt:
 788                         entry->fowner_op = &uid_gt;
 789                 case Opt_fowner_lt:
 790                         if (token == Opt_fowner_lt)
 791                                 entry->fowner_op = &uid_lt;
 792                 case Opt_fowner_eq:
 793                         ima_log_string_op(ab, "fowner", args[0].from,
 794                                           entry->fowner_op);
 795
 796                         if (uid_valid(entry->fowner)) {
 797                                 result = -EINVAL;
 798                                 break;
 799                         }
 800
 801                         result = kstrtoul(args[0].from, 10, &lnum);
 802                         if (!result) {
 803                                 entry->fowner = make_kuid(current_user_ns(), (uid_t)lnum);
 804                                 if (!uid_valid(entry->fowner) || (((uid_t)lnum) != lnum))
 805                                         result = -EINVAL;
 806                                 else
 807                                         entry->flags |= IMA_FOWNER;
 808                         }
 809                         break;
 810                 case Opt_obj_user:
 811                         ima_log_string(ab, "obj_user", args[0].from);
 812                         result = ima_lsm_rule_init(entry, args,
 813                                                    LSM_OBJ_USER,
 814                                                    AUDIT_OBJ_USER);
 815                         break;
 816                 case Opt_obj_role:
 817                         ima_log_string(ab, "obj_role", args[0].from);
 818                         result = ima_lsm_rule_init(entry, args,
 819                                                    LSM_OBJ_ROLE,
 820                                                    AUDIT_OBJ_ROLE);
 821                         break;
 822                 case Opt_obj_type:
 823                         ima_log_string(ab, "obj_type", args[0].from);
 824                         result = ima_lsm_rule_init(entry, args,
 825                                                    LSM_OBJ_TYPE,
 826                                                    AUDIT_OBJ_TYPE);
 827                         break;
 828                 case Opt_subj_user:
 829                         ima_log_string(ab, "subj_user", args[0].from);
 830                         result = ima_lsm_rule_init(entry, args,
 831                                                    LSM_SUBJ_USER,
 832                                                    AUDIT_SUBJ_USER);
 833                         break;
 834                 case Opt_subj_role:
 835                         ima_log_string(ab, "subj_role", args[0].from);
 836                         result = ima_lsm_rule_init(entry, args,
 837                                                    LSM_SUBJ_ROLE,
 838                                                    AUDIT_SUBJ_ROLE);
 839                         break;
 840                 case Opt_subj_type:
 841                         ima_log_string(ab, "subj_type", args[0].from);
 842                         result = ima_lsm_rule_init(entry, args,
 843                                                    LSM_SUBJ_TYPE,
 844                                                    AUDIT_SUBJ_TYPE);
 845                         break;
 846                 case Opt_appraise_type:
 847                         if (entry->action != APPRAISE) {
 848                                 result = -EINVAL;
 849                                 break;
 850                         }
 851
 852                         ima_log_string(ab, "appraise_type", args[0].from);
 853                         if ((strcmp(args[0].from, "imasig")) == 0)
 854                                 entry->flags |= IMA_DIGSIG_REQUIRED;
 855                         else
 856                                 result = -EINVAL;
 857                         break;
 858                 case Opt_permit_directio:
 859                         entry->flags |= IMA_PERMIT_DIRECTIO;
 860                         break;
 861                 case Opt_pcr:
 862                         if (entry->action != MEASURE) {
 863                                 result = -EINVAL;
 864                                 break;
 865                         }
 866                         ima_log_string(ab, "pcr", args[0].from);
 867
 868                         result = kstrtoint(args[0].from, 10, &entry->pcr);
 869                         if (result || INVALID_PCR(entry->pcr))
 870                                 result = -EINVAL;
 871                         else
 872                                 entry->flags |= IMA_PCR;
 873
 874                         break;
 875                 case Opt_err:
 876                         ima_log_string(ab, "UNKNOWN", p);
 877                         result = -EINVAL;
 878                         break;
 879                 }
 880         }
 881         if (!result && (entry->action == UNKNOWN))
 882                 result = -EINVAL;
 883         else if (entry->func == MODULE_CHECK)
 884                 temp_ima_appraise |= IMA_APPRAISE_MODULES;
 885         else if (entry->func == FIRMWARE_CHECK)
 886                 temp_ima_appraise |= IMA_APPRAISE_FIRMWARE;
 887         else if (entry->func == POLICY_CHECK)
 888                 temp_ima_appraise |= IMA_APPRAISE_POLICY;
 889         audit_log_format(ab, "res=%d", !result);
 890         audit_log_end(ab);
 891         return result;
 892 }
 893
 894 /**
 895  * ima_parse_add_rule - add a rule to ima_policy_rules
 896  * @rule - ima measurement policy rule
 897  *
 898  * Avoid locking by allowing just one writer at a time in ima_write_policy()
 899  * Returns the length of the rule parsed, an error code on failure
 900  */
 901 ssize_t ima_parse_add_rule(char *rule)
 902 {
 903         static const char op[] = "update_policy";
 904         char *p;
 905         struct ima_rule_entry *entry;
 906         ssize_t result, len;
 907         int audit_info = 0;
 908
 909         p = strsep(&rule, "\n");
 910         len = strlen(p) + 1;
 911         p += strspn(p, " \t");
 912
 913         if (*p == '#' || *p == '\0')
 914                 return len;
 915
 916         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 917         if (!entry) {
 918                 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
 919                                     NULL, op, "-ENOMEM", -ENOMEM, audit_info);
 920                 return -ENOMEM;
 921         }
 922
 923         INIT_LIST_HEAD(&entry->list);
 924
 925         result = ima_parse_rule(p, entry);
 926         if (result) {
 927                 kfree(entry);
 928                 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
 929                                     NULL, op, "invalid-policy", result,
 930                                     audit_info);
 931                 return result;
 932         }
 933
 934         list_add_tail(&entry->list, &ima_temp_rules);
 935
 936         return len;
 937 }
 938
 939 /**
 940  * ima_delete_rules() called to cleanup invalid in-flight policy.
 941  * We don't need locking as we operate on the temp list, which is
 942  * different from the active one.  There is also only one user of
 943  * ima_delete_rules() at a time.
 944  */
 945 void ima_delete_rules(void)
 946 {
 947         struct ima_rule_entry *entry, *tmp;
 948         int i;
 949
 950         temp_ima_appraise = 0;
 951         list_for_each_entry_safe(entry, tmp, &ima_temp_rules, list) {
 952                 for (i = 0; i < MAX_LSM_RULES; i++)
 953                         kfree(entry->lsm[i].args_p);
 954
 955                 list_del(&entry->list);
 956                 kfree(entry);
 957         }
 958 }
 959
 960 #ifdef  CONFIG_IMA_READ_POLICY
 961 enum {
 962         mask_exec = 0, mask_write, mask_read, mask_append
 963 };
 964
 965 static const char *const mask_tokens[] = {
 966         "^MAY_EXEC",
 967         "^MAY_WRITE",
 968         "^MAY_READ",
 969         "^MAY_APPEND"
 970 };
 971
 972 #define __ima_hook_stringify(str)       (#str),
 973
 974 static const char *const func_tokens[] = {
 975         __ima_hooks(__ima_hook_stringify)
 976 };
 977
 978 void *ima_policy_start(struct seq_file *m, loff_t *pos)
 979 {
 980         loff_t l = *pos;
 981         struct ima_rule_entry *entry;
 982
 983         rcu_read_lock();
 984         list_for_each_entry_rcu(entry, ima_rules, list) {
 985                 if (!l--) {
 986                         rcu_read_unlock();
 987                         return entry;
 988                 }
 989         }
 990         rcu_read_unlock();
 991         return NULL;
 992 }
 993
 994 void *ima_policy_next(struct seq_file *m, void *v, loff_t *pos)
 995 {
 996         struct ima_rule_entry *entry = v;
 997
 998         rcu_read_lock();
 999         entry = list_entry_rcu(entry->list.next, struct ima_rule_entry, list);
1000         rcu_read_unlock();
1001         (*pos)++;
1002
1003         return (&entry->list == ima_rules) ? NULL : entry;
1004 }
1005
1006 void ima_policy_stop(struct seq_file *m, void *v)
1007 {
1008 }
1009
1010 #define pt(token)       policy_tokens[token + Opt_err].pattern
1011 #define mt(token)       mask_tokens[token]
1012
1013 /*
1014  * policy_func_show - display the ima_hooks policy rule
1015  */
1016 static void policy_func_show(struct seq_file *m, enum ima_hooks func)
1017 {
1018         if (func > 0 && func < MAX_CHECK)
1019                 seq_printf(m, "func=%s ", func_tokens[func]);
1020         else
1021                 seq_printf(m, "func=%d ", func);
1022 }
1023
1024 int ima_policy_show(struct seq_file *m, void *v)
1025 {
1026         struct ima_rule_entry *entry = v;
1027         int i;
1028         char tbuf[64] = {0,};
1029         int offset = 0;
1030
1031         rcu_read_lock();
1032
1033         if (entry->action & MEASURE)
1034                 seq_puts(m, pt(Opt_measure));
1035         if (entry->action & DONT_MEASURE)
1036                 seq_puts(m, pt(Opt_dont_measure));
1037         if (entry->action & APPRAISE)
1038                 seq_puts(m, pt(Opt_appraise));
1039         if (entry->action & DONT_APPRAISE)
1040                 seq_puts(m, pt(Opt_dont_appraise));
1041         if (entry->action & AUDIT)
1042                 seq_puts(m, pt(Opt_audit));
1043
1044         seq_puts(m, " ");
1045
1046         if (entry->flags & IMA_FUNC)
1047                 policy_func_show(m, entry->func);
1048
1049         if ((entry->flags & IMA_MASK) || (entry->flags & IMA_INMASK)) {
1050                 if (entry->flags & IMA_MASK)
1051                         offset = 1;
1052                 if (entry->mask & MAY_EXEC)
1053                         seq_printf(m, pt(Opt_mask), mt(mask_exec) + offset);
1054                 if (entry->mask & MAY_WRITE)
1055                         seq_printf(m, pt(Opt_mask), mt(mask_write) + offset);
1056                 if (entry->mask & MAY_READ)
1057                         seq_printf(m, pt(Opt_mask), mt(mask_read) + offset);
1058                 if (entry->mask & MAY_APPEND)
1059                         seq_printf(m, pt(Opt_mask), mt(mask_append) + offset);
1060                 seq_puts(m, " ");
1061         }
1062
1063         if (entry->flags & IMA_FSMAGIC) {
1064                 snprintf(tbuf, sizeof(tbuf), "0x%lx", entry->fsmagic);
1065                 seq_printf(m, pt(Opt_fsmagic), tbuf);
1066                 seq_puts(m, " ");
1067         }
1068
1069         if (entry->flags & IMA_PCR) {
1070                 snprintf(tbuf, sizeof(tbuf), "%d", entry->pcr);
1071                 seq_printf(m, pt(Opt_pcr), tbuf);
1072                 seq_puts(m, " ");
1073         }
1074
1075         if (entry->flags & IMA_FSUUID) {
1076                 seq_printf(m, "fsuuid=%pU", &entry->fsuuid);
1077                 seq_puts(m, " ");
1078         }
1079
1080         if (entry->flags & IMA_UID) {
1081                 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
1082                 if (entry->uid_op == &uid_gt)
1083                         seq_printf(m, pt(Opt_uid_gt), tbuf);
1084                 else if (entry->uid_op == &uid_lt)
1085                         seq_printf(m, pt(Opt_uid_lt), tbuf);
1086                 else
1087                         seq_printf(m, pt(Opt_uid_eq), tbuf);
1088                 seq_puts(m, " ");
1089         }
1090
1091         if (entry->flags & IMA_EUID) {
1092                 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
1093                 if (entry->uid_op == &uid_gt)
1094                         seq_printf(m, pt(Opt_euid_gt), tbuf);
1095                 else if (entry->uid_op == &uid_lt)
1096                         seq_printf(m, pt(Opt_euid_lt), tbuf);
1097                 else
1098                         seq_printf(m, pt(Opt_euid_eq), tbuf);
1099                 seq_puts(m, " ");
1100         }
1101
1102         if (entry->flags & IMA_FOWNER) {
1103                 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->fowner));
1104                 if (entry->fowner_op == &uid_gt)
1105                         seq_printf(m, pt(Opt_fowner_gt), tbuf);
1106                 else if (entry->fowner_op == &uid_lt)
1107                         seq_printf(m, pt(Opt_fowner_lt), tbuf);
1108                 else
1109                         seq_printf(m, pt(Opt_fowner_eq), tbuf);
1110                 seq_puts(m, " ");
1111         }
1112
1113         for (i = 0; i < MAX_LSM_RULES; i++) {
1114                 if (entry->lsm[i].rule) {
1115                         switch (i) {
1116                         case LSM_OBJ_USER:
1117                                 seq_printf(m, pt(Opt_obj_user),
1118                                            (char *)entry->lsm[i].args_p);
1119                                 break;
1120                         case LSM_OBJ_ROLE:
1121                                 seq_printf(m, pt(Opt_obj_role),
1122                                            (char *)entry->lsm[i].args_p);
1123                                 break;
1124                         case LSM_OBJ_TYPE:
1125                                 seq_printf(m, pt(Opt_obj_type),
1126                                            (char *)entry->lsm[i].args_p);
1127                                 break;
1128                         case LSM_SUBJ_USER:
1129                                 seq_printf(m, pt(Opt_subj_user),
1130                                            (char *)entry->lsm[i].args_p);
1131                                 break;
1132                         case LSM_SUBJ_ROLE:
1133                                 seq_printf(m, pt(Opt_subj_role),
1134                                            (char *)entry->lsm[i].args_p);
1135                                 break;
1136                         case LSM_SUBJ_TYPE:
1137                                 seq_printf(m, pt(Opt_subj_type),
1138                                            (char *)entry->lsm[i].args_p);
1139                                 break;
1140                         }
1141                 }
1142         }
1143         if (entry->flags & IMA_DIGSIG_REQUIRED)
1144                 seq_puts(m, "appraise_type=imasig ");
1145         if (entry->flags & IMA_PERMIT_DIRECTIO)
1146                 seq_puts(m, "permit_directio ");
1147         rcu_read_unlock();
1148         seq_puts(m, "\n");
1149         return 0;
1150 }
1151 #endif  /* CONFIG_IMA_READ_POLICY */