security/integrity/ima/ima_policy.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2008 IBM Corporation
   4  * Author: Mimi Zohar <zohar@us.ibm.com>
   5  *
   6  * ima_policy.c
   7  *      - initialize default measure policy rules
   8  */
   9
  10 #include <linux/init.h>
  11 #include <linux/list.h>
  12 #include <linux/kernel_read_file.h>
  13 #include <linux/fs.h>
  14 #include <linux/security.h>
  15 #include <linux/magic.h>
  16 #include <linux/parser.h>
  17 #include <linux/slab.h>
  18 #include <linux/rculist.h>
  19 #include <linux/seq_file.h>
  20 #include <linux/ima.h>
  21
  22 #include "ima.h"
  23
  24 /* flags definitions */
  25 #define IMA_FUNC        0x0001
  26 #define IMA_MASK        0x0002
  27 #define IMA_FSMAGIC     0x0004
  28 #define IMA_UID         0x0008
  29 #define IMA_FOWNER      0x0010
  30 #define IMA_FSUUID      0x0020
  31 #define IMA_INMASK      0x0040
  32 #define IMA_EUID        0x0080
  33 #define IMA_PCR         0x0100
  34 #define IMA_FSNAME      0x0200
  35 #define IMA_KEYRINGS    0x0400
  36 #define IMA_LABEL       0x0800
  37 #define IMA_VALIDATE_ALGOS      0x1000
  38 #define IMA_GID         0x2000
  39 #define IMA_EGID        0x4000
  40 #define IMA_FGROUP      0x8000
  41
  42 #define UNKNOWN         0
  43 #define MEASURE         0x0001  /* same as IMA_MEASURE */
  44 #define DONT_MEASURE    0x0002
  45 #define APPRAISE        0x0004  /* same as IMA_APPRAISE */
  46 #define DONT_APPRAISE   0x0008
  47 #define AUDIT           0x0040
  48 #define HASH            0x0100
  49 #define DONT_HASH       0x0200
  50
  51 #define INVALID_PCR(a) (((a) < 0) || \
  52         (a) >= (sizeof_field(struct integrity_iint_cache, measured_pcrs) * 8))
  53
  54 int ima_policy_flag;
  55 static int temp_ima_appraise;
  56 static int build_ima_appraise __ro_after_init;
  57
  58 atomic_t ima_setxattr_allowed_hash_algorithms;
  59
  60 #define MAX_LSM_RULES 6
  61 enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
  62         LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
  63 };
  64
  65 enum policy_types { ORIGINAL_TCB = 1, DEFAULT_TCB };
  66
  67 enum policy_rule_list { IMA_DEFAULT_POLICY = 1, IMA_CUSTOM_POLICY };
  68
  69 struct ima_rule_opt_list {
  70         size_t count;
  71         char *items[];
  72 };
  73
  74 struct ima_rule_entry {
  75         struct list_head list;
  76         int action;
  77         unsigned int flags;
  78         enum ima_hooks func;
  79         int mask;
  80         unsigned long fsmagic;
  81         uuid_t fsuuid;
  82         kuid_t uid;
  83         kgid_t gid;
  84         kuid_t fowner;
  85         kgid_t fgroup;
  86         bool (*uid_op)(kuid_t cred_uid, kuid_t rule_uid);    /* Handlers for operators       */
  87         bool (*gid_op)(kgid_t cred_gid, kgid_t rule_gid);
  88         bool (*fowner_op)(kuid_t cred_uid, kuid_t rule_uid); /* uid_eq(), uid_gt(), uid_lt() */
  89         bool (*fgroup_op)(kgid_t cred_gid, kgid_t rule_gid); /* gid_eq(), gid_gt(), gid_lt() */
  90         int pcr;
  91         unsigned int allowed_algos; /* bitfield of allowed hash algorithms */
  92         struct {
  93                 void *rule;     /* LSM file metadata specific */
  94                 char *args_p;   /* audit value */
  95                 int type;       /* audit type */
  96         } lsm[MAX_LSM_RULES];
  97         char *fsname;
  98         struct ima_rule_opt_list *keyrings; /* Measure keys added to these keyrings */
  99         struct ima_rule_opt_list *label; /* Measure data grouped under this label */
 100         struct ima_template_desc *template;
 101 };
 102
 103 /*
 104  * sanity check in case the kernels gains more hash algorithms that can
 105  * fit in an unsigned int
 106  */
 107 static_assert(
 108         8 * sizeof(unsigned int) >= HASH_ALGO__LAST,
 109         "The bitfield allowed_algos in ima_rule_entry is too small to contain all the supported hash algorithms, consider using a bigger type");
 110
 111 /*
 112  * Without LSM specific knowledge, the default policy can only be
 113  * written in terms of .action, .func, .mask, .fsmagic, .uid, .gid,
 114  * .fowner, and .fgroup
 115  */
 116
 117 /*
 118  * The minimum rule set to allow for full TCB coverage.  Measures all files
 119  * opened or mmap for exec and everything read by root.  Dangerous because
 120  * normal users can easily run the machine out of memory simply building
 121  * and running executables.
 122  */
 123 static struct ima_rule_entry dont_measure_rules[] __ro_after_init = {
 124         {.action = DONT_MEASURE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 125         {.action = DONT_MEASURE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
 126         {.action = DONT_MEASURE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
 127         {.action = DONT_MEASURE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
 128         {.action = DONT_MEASURE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 129         {.action = DONT_MEASURE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
 130         {.action = DONT_MEASURE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
 131         {.action = DONT_MEASURE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
 132         {.action = DONT_MEASURE, .fsmagic = SMACK_MAGIC, .flags = IMA_FSMAGIC},
 133         {.action = DONT_MEASURE, .fsmagic = CGROUP_SUPER_MAGIC,
 134          .flags = IMA_FSMAGIC},
 135         {.action = DONT_MEASURE, .fsmagic = CGROUP2_SUPER_MAGIC,
 136          .flags = IMA_FSMAGIC},
 137         {.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
 138         {.action = DONT_MEASURE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC}
 139 };
 140
 141 static struct ima_rule_entry original_measurement_rules[] __ro_after_init = {
 142         {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
 143          .flags = IMA_FUNC | IMA_MASK},
 144         {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
 145          .flags = IMA_FUNC | IMA_MASK},
 146         {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
 147          .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
 148          .flags = IMA_FUNC | IMA_MASK | IMA_UID},
 149         {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
 150         {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
 151 };
 152
 153 static struct ima_rule_entry default_measurement_rules[] __ro_after_init = {
 154         {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
 155          .flags = IMA_FUNC | IMA_MASK},
 156         {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
 157          .flags = IMA_FUNC | IMA_MASK},
 158         {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
 159          .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
 160          .flags = IMA_FUNC | IMA_INMASK | IMA_EUID},
 161         {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
 162          .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
 163          .flags = IMA_FUNC | IMA_INMASK | IMA_UID},
 164         {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
 165         {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
 166         {.action = MEASURE, .func = POLICY_CHECK, .flags = IMA_FUNC},
 167 };
 168
 169 static struct ima_rule_entry default_appraise_rules[] __ro_after_init = {
 170         {.action = DONT_APPRAISE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 171         {.action = DONT_APPRAISE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
 172         {.action = DONT_APPRAISE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
 173         {.action = DONT_APPRAISE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
 174         {.action = DONT_APPRAISE, .fsmagic = RAMFS_MAGIC, .flags = IMA_FSMAGIC},
 175         {.action = DONT_APPRAISE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 176         {.action = DONT_APPRAISE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
 177         {.action = DONT_APPRAISE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
 178         {.action = DONT_APPRAISE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
 179         {.action = DONT_APPRAISE, .fsmagic = SMACK_MAGIC, .flags = IMA_FSMAGIC},
 180         {.action = DONT_APPRAISE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
 181         {.action = DONT_APPRAISE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC},
 182         {.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 183         {.action = DONT_APPRAISE, .fsmagic = CGROUP2_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 184 #ifdef CONFIG_IMA_WRITE_POLICY
 185         {.action = APPRAISE, .func = POLICY_CHECK,
 186         .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 187 #endif
 188 #ifndef CONFIG_IMA_APPRAISE_SIGNED_INIT
 189         {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &uid_eq,
 190          .flags = IMA_FOWNER},
 191 #else
 192         /* force signature */
 193         {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &uid_eq,
 194          .flags = IMA_FOWNER | IMA_DIGSIG_REQUIRED},
 195 #endif
 196 };
 197
 198 static struct ima_rule_entry build_appraise_rules[] __ro_after_init = {
 199 #ifdef CONFIG_IMA_APPRAISE_REQUIRE_MODULE_SIGS
 200         {.action = APPRAISE, .func = MODULE_CHECK,
 201          .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 202 #endif
 203 #ifdef CONFIG_IMA_APPRAISE_REQUIRE_FIRMWARE_SIGS
 204         {.action = APPRAISE, .func = FIRMWARE_CHECK,
 205          .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 206 #endif
 207 #ifdef CONFIG_IMA_APPRAISE_REQUIRE_KEXEC_SIGS
 208         {.action = APPRAISE, .func = KEXEC_KERNEL_CHECK,
 209          .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 210 #endif
 211 #ifdef CONFIG_IMA_APPRAISE_REQUIRE_POLICY_SIGS
 212         {.action = APPRAISE, .func = POLICY_CHECK,
 213          .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 214 #endif
 215 };
 216
 217 static struct ima_rule_entry secure_boot_rules[] __ro_after_init = {
 218         {.action = APPRAISE, .func = MODULE_CHECK,
 219          .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 220         {.action = APPRAISE, .func = FIRMWARE_CHECK,
 221          .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 222         {.action = APPRAISE, .func = KEXEC_KERNEL_CHECK,
 223          .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 224         {.action = APPRAISE, .func = POLICY_CHECK,
 225          .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 226 };
 227
 228 static struct ima_rule_entry critical_data_rules[] __ro_after_init = {
 229         {.action = MEASURE, .func = CRITICAL_DATA, .flags = IMA_FUNC},
 230 };
 231
 232 /* An array of architecture specific rules */
 233 static struct ima_rule_entry *arch_policy_entry __ro_after_init;
 234
 235 static LIST_HEAD(ima_default_rules);
 236 static LIST_HEAD(ima_policy_rules);
 237 static LIST_HEAD(ima_temp_rules);
 238 static struct list_head __rcu *ima_rules = (struct list_head __rcu *)(&ima_default_rules);
 239
 240 static int ima_policy __initdata;
 241
 242 static int __init default_measure_policy_setup(char *str)
 243 {
 244         if (ima_policy)
 245                 return 1;
 246
 247         ima_policy = ORIGINAL_TCB;
 248         return 1;
 249 }
 250 __setup("ima_tcb", default_measure_policy_setup);
 251
 252 static bool ima_use_appraise_tcb __initdata;
 253 static bool ima_use_secure_boot __initdata;
 254 static bool ima_use_critical_data __initdata;
 255 static bool ima_fail_unverifiable_sigs __ro_after_init;
 256 static int __init policy_setup(char *str)
 257 {
 258         char *p;
 259
 260         while ((p = strsep(&str, " |\n")) != NULL) {
 261                 if (*p == ' ')
 262                         continue;
 263                 if ((strcmp(p, "tcb") == 0) && !ima_policy)
 264                         ima_policy = DEFAULT_TCB;
 265                 else if (strcmp(p, "appraise_tcb") == 0)
 266                         ima_use_appraise_tcb = true;
 267                 else if (strcmp(p, "secure_boot") == 0)
 268                         ima_use_secure_boot = true;
 269                 else if (strcmp(p, "critical_data") == 0)
 270                         ima_use_critical_data = true;
 271                 else if (strcmp(p, "fail_securely") == 0)
 272                         ima_fail_unverifiable_sigs = true;
 273                 else
 274                         pr_err("policy \"%s\" not found", p);
 275         }
 276
 277         return 1;
 278 }
 279 __setup("ima_policy=", policy_setup);
 280
 281 static int __init default_appraise_policy_setup(char *str)
 282 {
 283         ima_use_appraise_tcb = true;
 284         return 1;
 285 }
 286 __setup("ima_appraise_tcb", default_appraise_policy_setup);
 287
 288 static struct ima_rule_opt_list *ima_alloc_rule_opt_list(const substring_t *src)
 289 {
 290         struct ima_rule_opt_list *opt_list;
 291         size_t count = 0;
 292         char *src_copy;
 293         char *cur, *next;
 294         size_t i;
 295
 296         src_copy = match_strdup(src);
 297         if (!src_copy)
 298                 return ERR_PTR(-ENOMEM);
 299
 300         next = src_copy;
 301         while ((cur = strsep(&next, "|"))) {
 302                 /* Don't accept an empty list item */
 303                 if (!(*cur)) {
 304                         kfree(src_copy);
 305                         return ERR_PTR(-EINVAL);
 306                 }
 307                 count++;
 308         }
 309
 310         /* Don't accept an empty list */
 311         if (!count) {
 312                 kfree(src_copy);
 313                 return ERR_PTR(-EINVAL);
 314         }
 315
 316         opt_list = kzalloc(struct_size(opt_list, items, count), GFP_KERNEL);
 317         if (!opt_list) {
 318                 kfree(src_copy);
 319                 return ERR_PTR(-ENOMEM);
 320         }
 321
 322         /*
 323          * strsep() has already replaced all instances of '|' with '\0',
 324          * leaving a byte sequence of NUL-terminated strings. Reference each
 325          * string with the array of items.
 326          *
 327          * IMPORTANT: Ownership of the allocated buffer is transferred from
 328          * src_copy to the first element in the items array. To free the
 329          * buffer, kfree() must only be called on the first element of the
 330          * array.
 331          */
 332         for (i = 0, cur = src_copy; i < count; i++) {
 333                 opt_list->items[i] = cur;
 334                 cur = strchr(cur, '\0') + 1;
 335         }
 336         opt_list->count = count;
 337
 338         return opt_list;
 339 }
 340
 341 static void ima_free_rule_opt_list(struct ima_rule_opt_list *opt_list)
 342 {
 343         if (!opt_list)
 344                 return;
 345
 346         if (opt_list->count) {
 347                 kfree(opt_list->items[0]);
 348                 opt_list->count = 0;
 349         }
 350
 351         kfree(opt_list);
 352 }
 353
 354 static void ima_lsm_free_rule(struct ima_rule_entry *entry)
 355 {
 356         int i;
 357
 358         for (i = 0; i < MAX_LSM_RULES; i++) {
 359                 ima_filter_rule_free(entry->lsm[i].rule);
 360                 kfree(entry->lsm[i].args_p);
 361         }
 362 }
 363
 364 static void ima_free_rule(struct ima_rule_entry *entry)
 365 {
 366         if (!entry)
 367                 return;
 368
 369         /*
 370          * entry->template->fields may be allocated in ima_parse_rule() but that
 371          * reference is owned by the corresponding ima_template_desc element in
 372          * the defined_templates list and cannot be freed here
 373          */
 374         kfree(entry->fsname);
 375         ima_free_rule_opt_list(entry->keyrings);
 376         ima_lsm_free_rule(entry);
 377         kfree(entry);
 378 }
 379
 380 static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
 381 {
 382         struct ima_rule_entry *nentry;
 383         int i;
 384
 385         /*
 386          * Immutable elements are copied over as pointers and data; only
 387          * lsm rules can change
 388          */
 389         nentry = kmemdup(entry, sizeof(*nentry), GFP_KERNEL);
 390         if (!nentry)
 391                 return NULL;
 392
 393         memset(nentry->lsm, 0, sizeof_field(struct ima_rule_entry, lsm));
 394
 395         for (i = 0; i < MAX_LSM_RULES; i++) {
 396                 if (!entry->lsm[i].args_p)
 397                         continue;
 398
 399                 nentry->lsm[i].type = entry->lsm[i].type;
 400                 nentry->lsm[i].args_p = entry->lsm[i].args_p;
 401                 /*
 402                  * Remove the reference from entry so that the associated
 403                  * memory will not be freed during a later call to
 404                  * ima_lsm_free_rule(entry).
 405                  */
 406                 entry->lsm[i].args_p = NULL;
 407
 408                 ima_filter_rule_init(nentry->lsm[i].type, Audit_equal,
 409                                      nentry->lsm[i].args_p,
 410                                      &nentry->lsm[i].rule);
 411                 if (!nentry->lsm[i].rule)
 412                         pr_warn("rule for LSM \'%s\' is undefined\n",
 413                                 nentry->lsm[i].args_p);
 414         }
 415         return nentry;
 416 }
 417
 418 static int ima_lsm_update_rule(struct ima_rule_entry *entry)
 419 {
 420         struct ima_rule_entry *nentry;
 421
 422         nentry = ima_lsm_copy_rule(entry);
 423         if (!nentry)
 424                 return -ENOMEM;
 425
 426         list_replace_rcu(&entry->list, &nentry->list);
 427         synchronize_rcu();
 428         /*
 429          * ima_lsm_copy_rule() shallow copied all references, except for the
 430          * LSM references, from entry to nentry so we only want to free the LSM
 431          * references and the entry itself. All other memory references will now
 432          * be owned by nentry.
 433          */
 434         ima_lsm_free_rule(entry);
 435         kfree(entry);
 436
 437         return 0;
 438 }
 439
 440 static bool ima_rule_contains_lsm_cond(struct ima_rule_entry *entry)
 441 {
 442         int i;
 443
 444         for (i = 0; i < MAX_LSM_RULES; i++)
 445                 if (entry->lsm[i].args_p)
 446                         return true;
 447
 448         return false;
 449 }
 450
 451 /*
 452  * The LSM policy can be reloaded, leaving the IMA LSM based rules referring
 453  * to the old, stale LSM policy.  Update the IMA LSM based rules to reflect
 454  * the reloaded LSM policy.
 455  */
 456 static void ima_lsm_update_rules(void)
 457 {
 458         struct ima_rule_entry *entry, *e;
 459         int result;
 460
 461         list_for_each_entry_safe(entry, e, &ima_policy_rules, list) {
 462                 if (!ima_rule_contains_lsm_cond(entry))
 463                         continue;
 464
 465                 result = ima_lsm_update_rule(entry);
 466                 if (result) {
 467                         pr_err("lsm rule update error %d\n", result);
 468                         return;
 469                 }
 470         }
 471 }
 472
 473 int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event,
 474                           void *lsm_data)
 475 {
 476         if (event != LSM_POLICY_CHANGE)
 477                 return NOTIFY_DONE;
 478
 479         ima_lsm_update_rules();
 480         return NOTIFY_OK;
 481 }
 482
 483 /**
 484  * ima_match_rule_data - determine whether func_data matches the policy rule
 485  * @rule: a pointer to a rule
 486  * @func_data: data to match against the measure rule data
 487  * @cred: a pointer to a credentials structure for user validation
 488  *
 489  * Returns true if func_data matches one in the rule, false otherwise.
 490  */
 491 static bool ima_match_rule_data(struct ima_rule_entry *rule,
 492                                 const char *func_data,
 493                                 const struct cred *cred)
 494 {
 495         const struct ima_rule_opt_list *opt_list = NULL;
 496         bool matched = false;
 497         size_t i;
 498
 499         if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid))
 500                 return false;
 501
 502         switch (rule->func) {
 503         case KEY_CHECK:
 504                 if (!rule->keyrings)
 505                         return true;
 506
 507                 opt_list = rule->keyrings;
 508                 break;
 509         case CRITICAL_DATA:
 510                 if (!rule->label)
 511                         return true;
 512
 513                 opt_list = rule->label;
 514                 break;
 515         default:
 516                 return false;
 517         }
 518
 519         if (!func_data)
 520                 return false;
 521
 522         for (i = 0; i < opt_list->count; i++) {
 523                 if (!strcmp(opt_list->items[i], func_data)) {
 524                         matched = true;
 525                         break;
 526                 }
 527         }
 528
 529         return matched;
 530 }
 531
 532 /**
 533  * ima_match_rules - determine whether an inode matches the policy rule.
 534  * @rule: a pointer to a rule
 535  * @mnt_userns: user namespace of the mount the inode was found from
 536  * @inode: a pointer to an inode
 537  * @cred: a pointer to a credentials structure for user validation
 538  * @secid: the secid of the task to be validated
 539  * @func: LIM hook identifier
 540  * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
 541  * @func_data: func specific data, may be NULL
 542  *
 543  * Returns true on rule match, false on failure.
 544  */
 545 static bool ima_match_rules(struct ima_rule_entry *rule,
 546                             struct user_namespace *mnt_userns,
 547                             struct inode *inode, const struct cred *cred,
 548                             u32 secid, enum ima_hooks func, int mask,
 549                             const char *func_data)
 550 {
 551         int i;
 552
 553         if ((rule->flags & IMA_FUNC) &&
 554             (rule->func != func && func != POST_SETATTR))
 555                 return false;
 556
 557         switch (func) {
 558         case KEY_CHECK:
 559         case CRITICAL_DATA:
 560                 return ((rule->func == func) &&
 561                         ima_match_rule_data(rule, func_data, cred));
 562         default:
 563                 break;
 564         }
 565
 566         if ((rule->flags & IMA_MASK) &&
 567             (rule->mask != mask && func != POST_SETATTR))
 568                 return false;
 569         if ((rule->flags & IMA_INMASK) &&
 570             (!(rule->mask & mask) && func != POST_SETATTR))
 571                 return false;
 572         if ((rule->flags & IMA_FSMAGIC)
 573             && rule->fsmagic != inode->i_sb->s_magic)
 574                 return false;
 575         if ((rule->flags & IMA_FSNAME)
 576             && strcmp(rule->fsname, inode->i_sb->s_type->name))
 577                 return false;
 578         if ((rule->flags & IMA_FSUUID) &&
 579             !uuid_equal(&rule->fsuuid, &inode->i_sb->s_uuid))
 580                 return false;
 581         if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid))
 582                 return false;
 583         if (rule->flags & IMA_EUID) {
 584                 if (has_capability_noaudit(current, CAP_SETUID)) {
 585                         if (!rule->uid_op(cred->euid, rule->uid)
 586                             && !rule->uid_op(cred->suid, rule->uid)
 587                             && !rule->uid_op(cred->uid, rule->uid))
 588                                 return false;
 589                 } else if (!rule->uid_op(cred->euid, rule->uid))
 590                         return false;
 591         }
 592         if ((rule->flags & IMA_GID) && !rule->gid_op(cred->gid, rule->gid))
 593                 return false;
 594         if (rule->flags & IMA_EGID) {
 595                 if (has_capability_noaudit(current, CAP_SETGID)) {
 596                         if (!rule->gid_op(cred->egid, rule->gid)
 597                             && !rule->gid_op(cred->sgid, rule->gid)
 598                             && !rule->gid_op(cred->gid, rule->gid))
 599                                 return false;
 600                 } else if (!rule->gid_op(cred->egid, rule->gid))
 601                         return false;
 602         }
 603         if ((rule->flags & IMA_FOWNER) &&
 604             !rule->fowner_op(i_uid_into_mnt(mnt_userns, inode), rule->fowner))
 605                 return false;
 606         if ((rule->flags & IMA_FGROUP) &&
 607             !rule->fgroup_op(i_gid_into_mnt(mnt_userns, inode), rule->fgroup))
 608                 return false;
 609         for (i = 0; i < MAX_LSM_RULES; i++) {
 610                 int rc = 0;
 611                 u32 osid;
 612
 613                 if (!rule->lsm[i].rule) {
 614                         if (!rule->lsm[i].args_p)
 615                                 continue;
 616                         else
 617                                 return false;
 618                 }
 619                 switch (i) {
 620                 case LSM_OBJ_USER:
 621                 case LSM_OBJ_ROLE:
 622                 case LSM_OBJ_TYPE:
 623                         security_inode_getsecid(inode, &osid);
 624                         rc = ima_filter_rule_match(osid, rule->lsm[i].type,
 625                                                    Audit_equal,
 626                                                    rule->lsm[i].rule);
 627                         break;
 628                 case LSM_SUBJ_USER:
 629                 case LSM_SUBJ_ROLE:
 630                 case LSM_SUBJ_TYPE:
 631                         rc = ima_filter_rule_match(secid, rule->lsm[i].type,
 632                                                    Audit_equal,
 633                                                    rule->lsm[i].rule);
 634                         break;
 635                 default:
 636                         break;
 637                 }
 638                 if (!rc)
 639                         return false;
 640         }
 641         return true;
 642 }
 643
 644 /*
 645  * In addition to knowing that we need to appraise the file in general,
 646  * we need to differentiate between calling hooks, for hook specific rules.
 647  */
 648 static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func)
 649 {
 650         if (!(rule->flags & IMA_FUNC))
 651                 return IMA_FILE_APPRAISE;
 652
 653         switch (func) {
 654         case MMAP_CHECK:
 655                 return IMA_MMAP_APPRAISE;
 656         case BPRM_CHECK:
 657                 return IMA_BPRM_APPRAISE;
 658         case CREDS_CHECK:
 659                 return IMA_CREDS_APPRAISE;
 660         case FILE_CHECK:
 661         case POST_SETATTR:
 662                 return IMA_FILE_APPRAISE;
 663         case MODULE_CHECK ... MAX_CHECK - 1:
 664         default:
 665                 return IMA_READ_APPRAISE;
 666         }
 667 }
 668
 669 /**
 670  * ima_match_policy - decision based on LSM and other conditions
 671  * @mnt_userns: user namespace of the mount the inode was found from
 672  * @inode: pointer to an inode for which the policy decision is being made
 673  * @cred: pointer to a credentials structure for which the policy decision is
 674  *        being made
 675  * @secid: LSM secid of the task to be validated
 676  * @func: IMA hook identifier
 677  * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
 678  * @pcr: set the pcr to extend
 679  * @template_desc: the template that should be used for this rule
 680  * @func_data: func specific data, may be NULL
 681  * @allowed_algos: allowlist of hash algorithms for the IMA xattr
 682  *
 683  * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
 684  * conditions.
 685  *
 686  * Since the IMA policy may be updated multiple times we need to lock the
 687  * list when walking it.  Reads are many orders of magnitude more numerous
 688  * than writes so ima_match_policy() is classical RCU candidate.
 689  */
 690 int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode,
 691                      const struct cred *cred, u32 secid, enum ima_hooks func,
 692                      int mask, int flags, int *pcr,
 693                      struct ima_template_desc **template_desc,
 694                      const char *func_data, unsigned int *allowed_algos)
 695 {
 696         struct ima_rule_entry *entry;
 697         int action = 0, actmask = flags | (flags << 1);
 698         struct list_head *ima_rules_tmp;
 699
 700         if (template_desc && !*template_desc)
 701                 *template_desc = ima_template_desc_current();
 702
 703         rcu_read_lock();
 704         ima_rules_tmp = rcu_dereference(ima_rules);
 705         list_for_each_entry_rcu(entry, ima_rules_tmp, list) {
 706
 707                 if (!(entry->action & actmask))
 708                         continue;
 709
 710                 if (!ima_match_rules(entry, mnt_userns, inode, cred, secid,
 711                                      func, mask, func_data))
 712                         continue;
 713
 714                 action |= entry->flags & IMA_NONACTION_FLAGS;
 715
 716                 action |= entry->action & IMA_DO_MASK;
 717                 if (entry->action & IMA_APPRAISE) {
 718                         action |= get_subaction(entry, func);
 719                         action &= ~IMA_HASH;
 720                         if (ima_fail_unverifiable_sigs)
 721                                 action |= IMA_FAIL_UNVERIFIABLE_SIGS;
 722
 723                         if (allowed_algos &&
 724                             entry->flags & IMA_VALIDATE_ALGOS)
 725                                 *allowed_algos = entry->allowed_algos;
 726                 }
 727
 728                 if (entry->action & IMA_DO_MASK)
 729                         actmask &= ~(entry->action | entry->action << 1);
 730                 else
 731                         actmask &= ~(entry->action | entry->action >> 1);
 732
 733                 if ((pcr) && (entry->flags & IMA_PCR))
 734                         *pcr = entry->pcr;
 735
 736                 if (template_desc && entry->template)
 737                         *template_desc = entry->template;
 738
 739                 if (!actmask)
 740                         break;
 741         }
 742         rcu_read_unlock();
 743
 744         return action;
 745 }
 746
 747 /**
 748  * ima_update_policy_flags() - Update global IMA variables
 749  *
 750  * Update ima_policy_flag and ima_setxattr_allowed_hash_algorithms
 751  * based on the currently loaded policy.
 752  *
 753  * With ima_policy_flag, the decision to short circuit out of a function
 754  * or not call the function in the first place can be made earlier.
 755  *
 756  * With ima_setxattr_allowed_hash_algorithms, the policy can restrict the
 757  * set of hash algorithms accepted when updating the security.ima xattr of
 758  * a file.
 759  *
 760  * Context: called after a policy update and at system initialization.
 761  */
 762 void ima_update_policy_flags(void)
 763 {
 764         struct ima_rule_entry *entry;
 765         int new_policy_flag = 0;
 766         struct list_head *ima_rules_tmp;
 767
 768         rcu_read_lock();
 769         ima_rules_tmp = rcu_dereference(ima_rules);
 770         list_for_each_entry_rcu(entry, ima_rules_tmp, list) {
 771                 /*
 772                  * SETXATTR_CHECK rules do not implement a full policy check
 773                  * because rule checking would probably have an important
 774                  * performance impact on setxattr(). As a consequence, only one
 775                  * SETXATTR_CHECK can be active at a given time.
 776                  * Because we want to preserve that property, we set out to use
 777                  * atomic_cmpxchg. Either:
 778                  * - the atomic was non-zero: a setxattr hash policy is
 779                  *   already enforced, we do nothing
 780                  * - the atomic was zero: no setxattr policy was set, enable
 781                  *   the setxattr hash policy
 782                  */
 783                 if (entry->func == SETXATTR_CHECK) {
 784                         atomic_cmpxchg(&ima_setxattr_allowed_hash_algorithms,
 785                                        0, entry->allowed_algos);
 786                         /* SETXATTR_CHECK doesn't impact ima_policy_flag */
 787                         continue;
 788                 }
 789
 790                 if (entry->action & IMA_DO_MASK)
 791                         new_policy_flag |= entry->action;
 792         }
 793         rcu_read_unlock();
 794
 795         ima_appraise |= (build_ima_appraise | temp_ima_appraise);
 796         if (!ima_appraise)
 797                 new_policy_flag &= ~IMA_APPRAISE;
 798
 799         ima_policy_flag = new_policy_flag;
 800 }
 801
 802 static int ima_appraise_flag(enum ima_hooks func)
 803 {
 804         if (func == MODULE_CHECK)
 805                 return IMA_APPRAISE_MODULES;
 806         else if (func == FIRMWARE_CHECK)
 807                 return IMA_APPRAISE_FIRMWARE;
 808         else if (func == POLICY_CHECK)
 809                 return IMA_APPRAISE_POLICY;
 810         else if (func == KEXEC_KERNEL_CHECK)
 811                 return IMA_APPRAISE_KEXEC;
 812         return 0;
 813 }
 814
 815 static void add_rules(struct ima_rule_entry *entries, int count,
 816                       enum policy_rule_list policy_rule)
 817 {
 818         int i = 0;
 819
 820         for (i = 0; i < count; i++) {
 821                 struct ima_rule_entry *entry;
 822
 823                 if (policy_rule & IMA_DEFAULT_POLICY)
 824                         list_add_tail(&entries[i].list, &ima_default_rules);
 825
 826                 if (policy_rule & IMA_CUSTOM_POLICY) {
 827                         entry = kmemdup(&entries[i], sizeof(*entry),
 828                                         GFP_KERNEL);
 829                         if (!entry)
 830                                 continue;
 831
 832                         list_add_tail(&entry->list, &ima_policy_rules);
 833                 }
 834                 if (entries[i].action == APPRAISE) {
 835                         if (entries != build_appraise_rules)
 836                                 temp_ima_appraise |=
 837                                         ima_appraise_flag(entries[i].func);
 838                         else
 839                                 build_ima_appraise |=
 840                                         ima_appraise_flag(entries[i].func);
 841                 }
 842         }
 843 }
 844
 845 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry);
 846
 847 static int __init ima_init_arch_policy(void)
 848 {
 849         const char * const *arch_rules;
 850         const char * const *rules;
 851         int arch_entries = 0;
 852         int i = 0;
 853
 854         arch_rules = arch_get_ima_policy();
 855         if (!arch_rules)
 856                 return arch_entries;
 857
 858         /* Get number of rules */
 859         for (rules = arch_rules; *rules != NULL; rules++)
 860                 arch_entries++;
 861
 862         arch_policy_entry = kcalloc(arch_entries + 1,
 863                                     sizeof(*arch_policy_entry), GFP_KERNEL);
 864         if (!arch_policy_entry)
 865                 return 0;
 866
 867         /* Convert each policy string rules to struct ima_rule_entry format */
 868         for (rules = arch_rules, i = 0; *rules != NULL; rules++) {
 869                 char rule[255];
 870                 int result;
 871
 872                 result = strscpy(rule, *rules, sizeof(rule));
 873
 874                 INIT_LIST_HEAD(&arch_policy_entry[i].list);
 875                 result = ima_parse_rule(rule, &arch_policy_entry[i]);
 876                 if (result) {
 877                         pr_warn("Skipping unknown architecture policy rule: %s\n",
 878                                 rule);
 879                         memset(&arch_policy_entry[i], 0,
 880                                sizeof(*arch_policy_entry));
 881                         continue;
 882                 }
 883                 i++;
 884         }
 885         return i;
 886 }
 887
 888 /**
 889  * ima_init_policy - initialize the default measure rules.
 890  *
 891  * ima_rules points to either the ima_default_rules or the new ima_policy_rules.
 892  */
 893 void __init ima_init_policy(void)
 894 {
 895         int build_appraise_entries, arch_entries;
 896
 897         /* if !ima_policy, we load NO default rules */
 898         if (ima_policy)
 899                 add_rules(dont_measure_rules, ARRAY_SIZE(dont_measure_rules),
 900                           IMA_DEFAULT_POLICY);
 901
 902         switch (ima_policy) {
 903         case ORIGINAL_TCB:
 904                 add_rules(original_measurement_rules,
 905                           ARRAY_SIZE(original_measurement_rules),
 906                           IMA_DEFAULT_POLICY);
 907                 break;
 908         case DEFAULT_TCB:
 909                 add_rules(default_measurement_rules,
 910                           ARRAY_SIZE(default_measurement_rules),
 911                           IMA_DEFAULT_POLICY);
 912                 break;
 913         default:
 914                 break;
 915         }
 916
 917         /*
 918          * Based on runtime secure boot flags, insert arch specific measurement
 919          * and appraise rules requiring file signatures for both the initial
 920          * and custom policies, prior to other appraise rules.
 921          * (Highest priority)
 922          */
 923         arch_entries = ima_init_arch_policy();
 924         if (!arch_entries)
 925                 pr_info("No architecture policies found\n");
 926         else
 927                 add_rules(arch_policy_entry, arch_entries,
 928                           IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY);
 929
 930         /*
 931          * Insert the builtin "secure_boot" policy rules requiring file
 932          * signatures, prior to other appraise rules.
 933          */
 934         if (ima_use_secure_boot)
 935                 add_rules(secure_boot_rules, ARRAY_SIZE(secure_boot_rules),
 936                           IMA_DEFAULT_POLICY);
 937
 938         /*
 939          * Insert the build time appraise rules requiring file signatures
 940          * for both the initial and custom policies, prior to other appraise
 941          * rules. As the secure boot rules includes all of the build time
 942          * rules, include either one or the other set of rules, but not both.
 943          */
 944         build_appraise_entries = ARRAY_SIZE(build_appraise_rules);
 945         if (build_appraise_entries) {
 946                 if (ima_use_secure_boot)
 947                         add_rules(build_appraise_rules, build_appraise_entries,
 948                                   IMA_CUSTOM_POLICY);
 949                 else
 950                         add_rules(build_appraise_rules, build_appraise_entries,
 951                                   IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY);
 952         }
 953
 954         if (ima_use_appraise_tcb)
 955                 add_rules(default_appraise_rules,
 956                           ARRAY_SIZE(default_appraise_rules),
 957                           IMA_DEFAULT_POLICY);
 958
 959         if (ima_use_critical_data)
 960                 add_rules(critical_data_rules,
 961                           ARRAY_SIZE(critical_data_rules),
 962                           IMA_DEFAULT_POLICY);
 963
 964         atomic_set(&ima_setxattr_allowed_hash_algorithms, 0);
 965
 966         ima_update_policy_flags();
 967 }
 968
 969 /* Make sure we have a valid policy, at least containing some rules. */
 970 int ima_check_policy(void)
 971 {
 972         if (list_empty(&ima_temp_rules))
 973                 return -EINVAL;
 974         return 0;
 975 }
 976
 977 /**
 978  * ima_update_policy - update default_rules with new measure rules
 979  *
 980  * Called on file .release to update the default rules with a complete new
 981  * policy.  What we do here is to splice ima_policy_rules and ima_temp_rules so
 982  * they make a queue.  The policy may be updated multiple times and this is the
 983  * RCU updater.
 984  *
 985  * Policy rules are never deleted so ima_policy_flag gets zeroed only once when
 986  * we switch from the default policy to user defined.
 987  */
 988 void ima_update_policy(void)
 989 {
 990         struct list_head *policy = &ima_policy_rules;
 991
 992         list_splice_tail_init_rcu(&ima_temp_rules, policy, synchronize_rcu);
 993
 994         if (ima_rules != (struct list_head __rcu *)policy) {
 995                 ima_policy_flag = 0;
 996
 997                 rcu_assign_pointer(ima_rules, policy);
 998                 /*
 999                  * IMA architecture specific policy rules are specified
1000                  * as strings and converted to an array of ima_entry_rules
1001                  * on boot.  After loading a custom policy, free the
1002                  * architecture specific rules stored as an array.
1003                  */
1004                 kfree(arch_policy_entry);
1005         }
1006         ima_update_policy_flags();
1007
1008         /* Custom IMA policy has been loaded */
1009         ima_process_queued_keys();
1010 }
1011
1012 /* Keep the enumeration in sync with the policy_tokens! */
1013 enum policy_opt {
1014         Opt_measure, Opt_dont_measure,
1015         Opt_appraise, Opt_dont_appraise,
1016         Opt_audit, Opt_hash, Opt_dont_hash,
1017         Opt_obj_user, Opt_obj_role, Opt_obj_type,
1018         Opt_subj_user, Opt_subj_role, Opt_subj_type,
1019         Opt_func, Opt_mask, Opt_fsmagic, Opt_fsname, Opt_fsuuid,
1020         Opt_uid_eq, Opt_euid_eq, Opt_gid_eq, Opt_egid_eq,
1021         Opt_fowner_eq, Opt_fgroup_eq,
1022         Opt_uid_gt, Opt_euid_gt, Opt_gid_gt, Opt_egid_gt,
1023         Opt_fowner_gt, Opt_fgroup_gt,
1024         Opt_uid_lt, Opt_euid_lt, Opt_gid_lt, Opt_egid_lt,
1025         Opt_fowner_lt, Opt_fgroup_lt,
1026         Opt_digest_type,
1027         Opt_appraise_type, Opt_appraise_flag, Opt_appraise_algos,
1028         Opt_permit_directio, Opt_pcr, Opt_template, Opt_keyrings,
1029         Opt_label, Opt_err
1030 };
1031
1032 static const match_table_t policy_tokens = {
1033         {Opt_measure, "measure"},
1034         {Opt_dont_measure, "dont_measure"},
1035         {Opt_appraise, "appraise"},
1036         {Opt_dont_appraise, "dont_appraise"},
1037         {Opt_audit, "audit"},
1038         {Opt_hash, "hash"},
1039         {Opt_dont_hash, "dont_hash"},
1040         {Opt_obj_user, "obj_user=%s"},
1041         {Opt_obj_role, "obj_role=%s"},
1042         {Opt_obj_type, "obj_type=%s"},
1043         {Opt_subj_user, "subj_user=%s"},
1044         {Opt_subj_role, "subj_role=%s"},
1045         {Opt_subj_type, "subj_type=%s"},
1046         {Opt_func, "func=%s"},
1047         {Opt_mask, "mask=%s"},
1048         {Opt_fsmagic, "fsmagic=%s"},
1049         {Opt_fsname, "fsname=%s"},
1050         {Opt_fsuuid, "fsuuid=%s"},
1051         {Opt_uid_eq, "uid=%s"},
1052         {Opt_euid_eq, "euid=%s"},
1053         {Opt_gid_eq, "gid=%s"},
1054         {Opt_egid_eq, "egid=%s"},
1055         {Opt_fowner_eq, "fowner=%s"},
1056         {Opt_fgroup_eq, "fgroup=%s"},
1057         {Opt_uid_gt, "uid>%s"},
1058         {Opt_euid_gt, "euid>%s"},
1059         {Opt_gid_gt, "gid>%s"},
1060         {Opt_egid_gt, "egid>%s"},
1061         {Opt_fowner_gt, "fowner>%s"},
1062         {Opt_fgroup_gt, "fgroup>%s"},
1063         {Opt_uid_lt, "uid<%s"},
1064         {Opt_euid_lt, "euid<%s"},
1065         {Opt_gid_lt, "gid<%s"},
1066         {Opt_egid_lt, "egid<%s"},
1067         {Opt_fowner_lt, "fowner<%s"},
1068         {Opt_fgroup_lt, "fgroup<%s"},
1069         {Opt_digest_type, "digest_type=%s"},
1070         {Opt_appraise_type, "appraise_type=%s"},
1071         {Opt_appraise_flag, "appraise_flag=%s"},
1072         {Opt_appraise_algos, "appraise_algos=%s"},
1073         {Opt_permit_directio, "permit_directio"},
1074         {Opt_pcr, "pcr=%s"},
1075         {Opt_template, "template=%s"},
1076         {Opt_keyrings, "keyrings=%s"},
1077         {Opt_label, "label=%s"},
1078         {Opt_err, NULL}
1079 };
1080
1081 static int ima_lsm_rule_init(struct ima_rule_entry *entry,
1082                              substring_t *args, int lsm_rule, int audit_type)
1083 {
1084         int result;
1085
1086         if (entry->lsm[lsm_rule].rule)
1087                 return -EINVAL;
1088
1089         entry->lsm[lsm_rule].args_p = match_strdup(args);
1090         if (!entry->lsm[lsm_rule].args_p)
1091                 return -ENOMEM;
1092
1093         entry->lsm[lsm_rule].type = audit_type;
1094         result = ima_filter_rule_init(entry->lsm[lsm_rule].type, Audit_equal,
1095                                       entry->lsm[lsm_rule].args_p,
1096                                       &entry->lsm[lsm_rule].rule);
1097         if (!entry->lsm[lsm_rule].rule) {
1098                 pr_warn("rule for LSM \'%s\' is undefined\n",
1099                         entry->lsm[lsm_rule].args_p);
1100
1101                 if (ima_rules == (struct list_head __rcu *)(&ima_default_rules)) {
1102                         kfree(entry->lsm[lsm_rule].args_p);
1103                         entry->lsm[lsm_rule].args_p = NULL;
1104                         result = -EINVAL;
1105                 } else
1106                         result = 0;
1107         }
1108
1109         return result;
1110 }
1111
1112 static void ima_log_string_op(struct audit_buffer *ab, char *key, char *value,
1113                               enum policy_opt rule_operator)
1114 {
1115         if (!ab)
1116                 return;
1117
1118         switch (rule_operator) {
1119         case Opt_uid_gt:
1120         case Opt_euid_gt:
1121         case Opt_gid_gt:
1122         case Opt_egid_gt:
1123         case Opt_fowner_gt:
1124         case Opt_fgroup_gt:
1125                 audit_log_format(ab, "%s>", key);
1126                 break;
1127         case Opt_uid_lt:
1128         case Opt_euid_lt:
1129         case Opt_gid_lt:
1130         case Opt_egid_lt:
1131         case Opt_fowner_lt:
1132         case Opt_fgroup_lt:
1133                 audit_log_format(ab, "%s<", key);
1134                 break;
1135         default:
1136                 audit_log_format(ab, "%s=", key);
1137         }
1138         audit_log_format(ab, "%s ", value);
1139 }
1140 static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
1141 {
1142         ima_log_string_op(ab, key, value, Opt_err);
1143 }
1144
1145 /*
1146  * Validating the appended signature included in the measurement list requires
1147  * the file hash calculated without the appended signature (i.e., the 'd-modsig'
1148  * field). Therefore, notify the user if they have the 'modsig' field but not
1149  * the 'd-modsig' field in the template.
1150  */
1151 static void check_template_modsig(const struct ima_template_desc *template)
1152 {
1153 #define MSG "template with 'modsig' field also needs 'd-modsig' field\n"
1154         bool has_modsig, has_dmodsig;
1155         static bool checked;
1156         int i;
1157
1158         /* We only need to notify the user once. */
1159         if (checked)
1160                 return;
1161
1162         has_modsig = has_dmodsig = false;
1163         for (i = 0; i < template->num_fields; i++) {
1164                 if (!strcmp(template->fields[i]->field_id, "modsig"))
1165                         has_modsig = true;
1166                 else if (!strcmp(template->fields[i]->field_id, "d-modsig"))
1167                         has_dmodsig = true;
1168         }
1169
1170         if (has_modsig && !has_dmodsig)
1171                 pr_notice(MSG);
1172
1173         checked = true;
1174 #undef MSG
1175 }
1176
1177 /*
1178  * Warn if the template does not contain the given field.
1179  */
1180 static void check_template_field(const struct ima_template_desc *template,
1181                                  const char *field, const char *msg)
1182 {
1183         int i;
1184
1185         for (i = 0; i < template->num_fields; i++)
1186                 if (!strcmp(template->fields[i]->field_id, field))
1187                         return;
1188
1189         pr_notice_once("%s", msg);
1190 }
1191
1192 static bool ima_validate_rule(struct ima_rule_entry *entry)
1193 {
1194         /* Ensure that the action is set and is compatible with the flags */
1195         if (entry->action == UNKNOWN)
1196                 return false;
1197
1198         if (entry->action != MEASURE && entry->flags & IMA_PCR)
1199                 return false;
1200
1201         if (entry->action != APPRAISE &&
1202             entry->flags & (IMA_DIGSIG_REQUIRED | IMA_MODSIG_ALLOWED |
1203                             IMA_CHECK_BLACKLIST | IMA_VALIDATE_ALGOS))
1204                 return false;
1205
1206         /*
1207          * The IMA_FUNC bit must be set if and only if there's a valid hook
1208          * function specified, and vice versa. Enforcing this property allows
1209          * for the NONE case below to validate a rule without an explicit hook
1210          * function.
1211          */
1212         if (((entry->flags & IMA_FUNC) && entry->func == NONE) ||
1213             (!(entry->flags & IMA_FUNC) && entry->func != NONE))
1214                 return false;
1215
1216         /*
1217          * Ensure that the hook function is compatible with the other
1218          * components of the rule
1219          */
1220         switch (entry->func) {
1221         case NONE:
1222         case FILE_CHECK:
1223         case MMAP_CHECK:
1224         case BPRM_CHECK:
1225         case CREDS_CHECK:
1226         case POST_SETATTR:
1227         case FIRMWARE_CHECK:
1228         case POLICY_CHECK:
1229                 if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
1230                                      IMA_UID | IMA_FOWNER | IMA_FSUUID |
1231                                      IMA_INMASK | IMA_EUID | IMA_PCR |
1232                                      IMA_FSNAME | IMA_GID | IMA_EGID |
1233                                      IMA_FGROUP | IMA_DIGSIG_REQUIRED |
1234                                      IMA_PERMIT_DIRECTIO | IMA_VALIDATE_ALGOS |
1235                                      IMA_VERITY_REQUIRED))
1236                         return false;
1237
1238                 break;
1239         case MODULE_CHECK:
1240         case KEXEC_KERNEL_CHECK:
1241         case KEXEC_INITRAMFS_CHECK:
1242                 if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
1243                                      IMA_UID | IMA_FOWNER | IMA_FSUUID |
1244                                      IMA_INMASK | IMA_EUID | IMA_PCR |
1245                                      IMA_FSNAME | IMA_GID | IMA_EGID |
1246                                      IMA_FGROUP | IMA_DIGSIG_REQUIRED |
1247                                      IMA_PERMIT_DIRECTIO | IMA_MODSIG_ALLOWED |
1248                                      IMA_CHECK_BLACKLIST | IMA_VALIDATE_ALGOS))
1249                         return false;
1250
1251                 break;
1252         case KEXEC_CMDLINE:
1253                 if (entry->action & ~(MEASURE | DONT_MEASURE))
1254                         return false;
1255
1256                 if (entry->flags & ~(IMA_FUNC | IMA_FSMAGIC | IMA_UID |
1257                                      IMA_FOWNER | IMA_FSUUID | IMA_EUID |
1258                                      IMA_PCR | IMA_FSNAME | IMA_GID | IMA_EGID |
1259                                      IMA_FGROUP))
1260                         return false;
1261
1262                 break;
1263         case KEY_CHECK:
1264                 if (entry->action & ~(MEASURE | DONT_MEASURE))
1265                         return false;
1266
1267                 if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_GID | IMA_PCR |
1268                                      IMA_KEYRINGS))
1269                         return false;
1270
1271                 if (ima_rule_contains_lsm_cond(entry))
1272                         return false;
1273
1274                 break;
1275         case CRITICAL_DATA:
1276                 if (entry->action & ~(MEASURE | DONT_MEASURE))
1277                         return false;
1278
1279                 if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_GID | IMA_PCR |
1280                                      IMA_LABEL))
1281                         return false;
1282
1283                 if (ima_rule_contains_lsm_cond(entry))
1284                         return false;
1285
1286                 break;
1287         case SETXATTR_CHECK:
1288                 /* any action other than APPRAISE is unsupported */
1289                 if (entry->action != APPRAISE)
1290                         return false;
1291
1292                 /* SETXATTR_CHECK requires an appraise_algos parameter */
1293                 if (!(entry->flags & IMA_VALIDATE_ALGOS))
1294                         return false;
1295
1296                 /*
1297                  * full policies are not supported, they would have too
1298                  * much of a performance impact
1299                  */
1300                 if (entry->flags & ~(IMA_FUNC | IMA_VALIDATE_ALGOS))
1301                         return false;
1302
1303                 break;
1304         default:
1305                 return false;
1306         }
1307
1308         /* Ensure that combinations of flags are compatible with each other */
1309         if (entry->flags & IMA_CHECK_BLACKLIST &&
1310             !(entry->flags & IMA_MODSIG_ALLOWED))
1311                 return false;
1312
1313         /*
1314          * Unlike for regular IMA 'appraise' policy rules where security.ima
1315          * xattr may contain either a file hash or signature, the security.ima
1316          * xattr for fsverity must contain a file signature (sigv3).  Ensure
1317          * that 'appraise' rules for fsverity require file signatures by
1318          * checking the IMA_DIGSIG_REQUIRED flag is set.
1319          */
1320         if (entry->action == APPRAISE &&
1321             (entry->flags & IMA_VERITY_REQUIRED) &&
1322             !(entry->flags & IMA_DIGSIG_REQUIRED))
1323                 return false;
1324
1325         return true;
1326 }
1327
1328 static unsigned int ima_parse_appraise_algos(char *arg)
1329 {
1330         unsigned int res = 0;
1331         int idx;
1332         char *token;
1333
1334         while ((token = strsep(&arg, ",")) != NULL) {
1335                 idx = match_string(hash_algo_name, HASH_ALGO__LAST, token);
1336
1337                 if (idx < 0) {
1338                         pr_err("unknown hash algorithm \"%s\"",
1339                                token);
1340                         return 0;
1341                 }
1342
1343                 if (!crypto_has_alg(hash_algo_name[idx], 0, 0)) {
1344                         pr_err("unavailable hash algorithm \"%s\", check your kernel configuration",
1345                                token);
1346                         return 0;
1347                 }
1348
1349                 /* Add the hash algorithm to the 'allowed' bitfield */
1350                 res |= (1U << idx);
1351         }
1352
1353         return res;
1354 }
1355
1356 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
1357 {
1358         struct audit_buffer *ab;
1359         char *from;
1360         char *p;
1361         bool eid_token; /* either euid or egid */
1362         struct ima_template_desc *template_desc;
1363         int result = 0;
1364
1365         ab = integrity_audit_log_start(audit_context(), GFP_KERNEL,
1366                                        AUDIT_INTEGRITY_POLICY_RULE);
1367
1368         entry->uid = INVALID_UID;
1369         entry->gid = INVALID_GID;
1370         entry->fowner = INVALID_UID;
1371         entry->fgroup = INVALID_GID;
1372         entry->uid_op = &uid_eq;
1373         entry->gid_op = &gid_eq;
1374         entry->fowner_op = &uid_eq;
1375         entry->fgroup_op = &gid_eq;
1376         entry->action = UNKNOWN;
1377         while ((p = strsep(&rule, " \t")) != NULL) {
1378                 substring_t args[MAX_OPT_ARGS];
1379                 int token;
1380                 unsigned long lnum;
1381
1382                 if (result < 0)
1383                         break;
1384                 if ((*p == '\0') || (*p == ' ') || (*p == '\t'))
1385                         continue;
1386                 token = match_token(p, policy_tokens, args);
1387                 switch (token) {
1388                 case Opt_measure:
1389                         ima_log_string(ab, "action", "measure");
1390
1391                         if (entry->action != UNKNOWN)
1392                                 result = -EINVAL;
1393
1394                         entry->action = MEASURE;
1395                         break;
1396                 case Opt_dont_measure:
1397                         ima_log_string(ab, "action", "dont_measure");
1398
1399                         if (entry->action != UNKNOWN)
1400                                 result = -EINVAL;
1401
1402                         entry->action = DONT_MEASURE;
1403                         break;
1404                 case Opt_appraise:
1405                         ima_log_string(ab, "action", "appraise");
1406
1407                         if (entry->action != UNKNOWN)
1408                                 result = -EINVAL;
1409
1410                         entry->action = APPRAISE;
1411                         break;
1412                 case Opt_dont_appraise:
1413                         ima_log_string(ab, "action", "dont_appraise");
1414
1415                         if (entry->action != UNKNOWN)
1416                                 result = -EINVAL;
1417
1418                         entry->action = DONT_APPRAISE;
1419                         break;
1420                 case Opt_audit:
1421                         ima_log_string(ab, "action", "audit");
1422
1423                         if (entry->action != UNKNOWN)
1424                                 result = -EINVAL;
1425
1426                         entry->action = AUDIT;
1427                         break;
1428                 case Opt_hash:
1429                         ima_log_string(ab, "action", "hash");
1430
1431                         if (entry->action != UNKNOWN)
1432                                 result = -EINVAL;
1433
1434                         entry->action = HASH;
1435                         break;
1436                 case Opt_dont_hash:
1437                         ima_log_string(ab, "action", "dont_hash");
1438
1439                         if (entry->action != UNKNOWN)
1440                                 result = -EINVAL;
1441
1442                         entry->action = DONT_HASH;
1443                         break;
1444                 case Opt_func:
1445                         ima_log_string(ab, "func", args[0].from);
1446
1447                         if (entry->func)
1448                                 result = -EINVAL;
1449
1450                         if (strcmp(args[0].from, "FILE_CHECK") == 0)
1451                                 entry->func = FILE_CHECK;
1452                         /* PATH_CHECK is for backwards compat */
1453                         else if (strcmp(args[0].from, "PATH_CHECK") == 0)
1454                                 entry->func = FILE_CHECK;
1455                         else if (strcmp(args[0].from, "MODULE_CHECK") == 0)
1456                                 entry->func = MODULE_CHECK;
1457                         else if (strcmp(args[0].from, "FIRMWARE_CHECK") == 0)
1458                                 entry->func = FIRMWARE_CHECK;
1459                         else if ((strcmp(args[0].from, "FILE_MMAP") == 0)
1460                                 || (strcmp(args[0].from, "MMAP_CHECK") == 0))
1461                                 entry->func = MMAP_CHECK;
1462                         else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
1463                                 entry->func = BPRM_CHECK;
1464                         else if (strcmp(args[0].from, "CREDS_CHECK") == 0)
1465                                 entry->func = CREDS_CHECK;
1466                         else if (strcmp(args[0].from, "KEXEC_KERNEL_CHECK") ==
1467                                  0)
1468                                 entry->func = KEXEC_KERNEL_CHECK;
1469                         else if (strcmp(args[0].from, "KEXEC_INITRAMFS_CHECK")
1470                                  == 0)
1471                                 entry->func = KEXEC_INITRAMFS_CHECK;
1472                         else if (strcmp(args[0].from, "POLICY_CHECK") == 0)
1473                                 entry->func = POLICY_CHECK;
1474                         else if (strcmp(args[0].from, "KEXEC_CMDLINE") == 0)
1475                                 entry->func = KEXEC_CMDLINE;
1476                         else if (IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) &&
1477                                  strcmp(args[0].from, "KEY_CHECK") == 0)
1478                                 entry->func = KEY_CHECK;
1479                         else if (strcmp(args[0].from, "CRITICAL_DATA") == 0)
1480                                 entry->func = CRITICAL_DATA;
1481                         else if (strcmp(args[0].from, "SETXATTR_CHECK") == 0)
1482                                 entry->func = SETXATTR_CHECK;
1483                         else
1484                                 result = -EINVAL;
1485                         if (!result)
1486                                 entry->flags |= IMA_FUNC;
1487                         break;
1488                 case Opt_mask:
1489                         ima_log_string(ab, "mask", args[0].from);
1490
1491                         if (entry->mask)
1492                                 result = -EINVAL;
1493
1494                         from = args[0].from;
1495                         if (*from == '^')
1496                                 from++;
1497
1498                         if ((strcmp(from, "MAY_EXEC")) == 0)
1499                                 entry->mask = MAY_EXEC;
1500                         else if (strcmp(from, "MAY_WRITE") == 0)
1501                                 entry->mask = MAY_WRITE;
1502                         else if (strcmp(from, "MAY_READ") == 0)
1503                                 entry->mask = MAY_READ;
1504                         else if (strcmp(from, "MAY_APPEND") == 0)
1505                                 entry->mask = MAY_APPEND;
1506                         else
1507                                 result = -EINVAL;
1508                         if (!result)
1509                                 entry->flags |= (*args[0].from == '^')
1510                                      ? IMA_INMASK : IMA_MASK;
1511                         break;
1512                 case Opt_fsmagic:
1513                         ima_log_string(ab, "fsmagic", args[0].from);
1514
1515                         if (entry->fsmagic) {
1516                                 result = -EINVAL;
1517                                 break;
1518                         }
1519
1520                         result = kstrtoul(args[0].from, 16, &entry->fsmagic);
1521                         if (!result)
1522                                 entry->flags |= IMA_FSMAGIC;
1523                         break;
1524                 case Opt_fsname:
1525                         ima_log_string(ab, "fsname", args[0].from);
1526
1527                         entry->fsname = kstrdup(args[0].from, GFP_KERNEL);
1528                         if (!entry->fsname) {
1529                                 result = -ENOMEM;
1530                                 break;
1531                         }
1532                         result = 0;
1533                         entry->flags |= IMA_FSNAME;
1534                         break;
1535                 case Opt_keyrings:
1536                         ima_log_string(ab, "keyrings", args[0].from);
1537
1538                         if (!IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) ||
1539                             entry->keyrings) {
1540                                 result = -EINVAL;
1541                                 break;
1542                         }
1543
1544                         entry->keyrings = ima_alloc_rule_opt_list(args);
1545                         if (IS_ERR(entry->keyrings)) {
1546                                 result = PTR_ERR(entry->keyrings);
1547                                 entry->keyrings = NULL;
1548                                 break;
1549                         }
1550
1551                         entry->flags |= IMA_KEYRINGS;
1552                         break;
1553                 case Opt_label:
1554                         ima_log_string(ab, "label", args[0].from);
1555
1556                         if (entry->label) {
1557                                 result = -EINVAL;
1558                                 break;
1559                         }
1560
1561                         entry->label = ima_alloc_rule_opt_list(args);
1562                         if (IS_ERR(entry->label)) {
1563                                 result = PTR_ERR(entry->label);
1564                                 entry->label = NULL;
1565                                 break;
1566                         }
1567
1568                         entry->flags |= IMA_LABEL;
1569                         break;
1570                 case Opt_fsuuid:
1571                         ima_log_string(ab, "fsuuid", args[0].from);
1572
1573                         if (!uuid_is_null(&entry->fsuuid)) {
1574                                 result = -EINVAL;
1575                                 break;
1576                         }
1577
1578                         result = uuid_parse(args[0].from, &entry->fsuuid);
1579                         if (!result)
1580                                 entry->flags |= IMA_FSUUID;
1581                         break;
1582                 case Opt_uid_gt:
1583                 case Opt_euid_gt:
1584                         entry->uid_op = &uid_gt;
1585                         fallthrough;
1586                 case Opt_uid_lt:
1587                 case Opt_euid_lt:
1588                         if ((token == Opt_uid_lt) || (token == Opt_euid_lt))
1589                                 entry->uid_op = &uid_lt;
1590                         fallthrough;
1591                 case Opt_uid_eq:
1592                 case Opt_euid_eq:
1593                         eid_token = (token == Opt_euid_eq) ||
1594                                     (token == Opt_euid_gt) ||
1595                                     (token == Opt_euid_lt);
1596
1597                         ima_log_string_op(ab, eid_token ? "euid" : "uid",
1598                                           args[0].from, token);
1599
1600                         if (uid_valid(entry->uid)) {
1601                                 result = -EINVAL;
1602                                 break;
1603                         }
1604
1605                         result = kstrtoul(args[0].from, 10, &lnum);
1606                         if (!result) {
1607                                 entry->uid = make_kuid(current_user_ns(),
1608                                                        (uid_t) lnum);
1609                                 if (!uid_valid(entry->uid) ||
1610                                     (uid_t)lnum != lnum)
1611                                         result = -EINVAL;
1612                                 else
1613                                         entry->flags |= eid_token
1614                                             ? IMA_EUID : IMA_UID;
1615                         }
1616                         break;
1617                 case Opt_gid_gt:
1618                 case Opt_egid_gt:
1619                         entry->gid_op = &gid_gt;
1620                         fallthrough;
1621                 case Opt_gid_lt:
1622                 case Opt_egid_lt:
1623                         if ((token == Opt_gid_lt) || (token == Opt_egid_lt))
1624                                 entry->gid_op = &gid_lt;
1625                         fallthrough;
1626                 case Opt_gid_eq:
1627                 case Opt_egid_eq:
1628                         eid_token = (token == Opt_egid_eq) ||
1629                                     (token == Opt_egid_gt) ||
1630                                     (token == Opt_egid_lt);
1631
1632                         ima_log_string_op(ab, eid_token ? "egid" : "gid",
1633                                           args[0].from, token);
1634
1635                         if (gid_valid(entry->gid)) {
1636                                 result = -EINVAL;
1637                                 break;
1638                         }
1639
1640                         result = kstrtoul(args[0].from, 10, &lnum);
1641                         if (!result) {
1642                                 entry->gid = make_kgid(current_user_ns(),
1643                                                        (gid_t)lnum);
1644                                 if (!gid_valid(entry->gid) ||
1645                                     (((gid_t)lnum) != lnum))
1646                                         result = -EINVAL;
1647                                 else
1648                                         entry->flags |= eid_token
1649                                             ? IMA_EGID : IMA_GID;
1650                         }
1651                         break;
1652                 case Opt_fowner_gt:
1653                         entry->fowner_op = &uid_gt;
1654                         fallthrough;
1655                 case Opt_fowner_lt:
1656                         if (token == Opt_fowner_lt)
1657                                 entry->fowner_op = &uid_lt;
1658                         fallthrough;
1659                 case Opt_fowner_eq:
1660                         ima_log_string_op(ab, "fowner", args[0].from, token);
1661
1662                         if (uid_valid(entry->fowner)) {
1663                                 result = -EINVAL;
1664                                 break;
1665                         }
1666
1667                         result = kstrtoul(args[0].from, 10, &lnum);
1668                         if (!result) {
1669                                 entry->fowner = make_kuid(current_user_ns(),
1670                                                           (uid_t)lnum);
1671                                 if (!uid_valid(entry->fowner) ||
1672                                     (((uid_t)lnum) != lnum))
1673                                         result = -EINVAL;
1674                                 else
1675                                         entry->flags |= IMA_FOWNER;
1676                         }
1677                         break;
1678                 case Opt_fgroup_gt:
1679                         entry->fgroup_op = &gid_gt;
1680                         fallthrough;
1681                 case Opt_fgroup_lt:
1682                         if (token == Opt_fgroup_lt)
1683                                 entry->fgroup_op = &gid_lt;
1684                         fallthrough;
1685                 case Opt_fgroup_eq:
1686                         ima_log_string_op(ab, "fgroup", args[0].from, token);
1687
1688                         if (gid_valid(entry->fgroup)) {
1689                                 result = -EINVAL;
1690                                 break;
1691                         }
1692
1693                         result = kstrtoul(args[0].from, 10, &lnum);
1694                         if (!result) {
1695                                 entry->fgroup = make_kgid(current_user_ns(),
1696                                                           (gid_t)lnum);
1697                                 if (!gid_valid(entry->fgroup) ||
1698                                     (((gid_t)lnum) != lnum))
1699                                         result = -EINVAL;
1700                                 else
1701                                         entry->flags |= IMA_FGROUP;
1702                         }
1703                         break;
1704                 case Opt_obj_user:
1705                         ima_log_string(ab, "obj_user", args[0].from);
1706                         result = ima_lsm_rule_init(entry, args,
1707                                                    LSM_OBJ_USER,
1708                                                    AUDIT_OBJ_USER);
1709                         break;
1710                 case Opt_obj_role:
1711                         ima_log_string(ab, "obj_role", args[0].from);
1712                         result = ima_lsm_rule_init(entry, args,
1713                                                    LSM_OBJ_ROLE,
1714                                                    AUDIT_OBJ_ROLE);
1715                         break;
1716                 case Opt_obj_type:
1717                         ima_log_string(ab, "obj_type", args[0].from);
1718                         result = ima_lsm_rule_init(entry, args,
1719                                                    LSM_OBJ_TYPE,
1720                                                    AUDIT_OBJ_TYPE);
1721                         break;
1722                 case Opt_subj_user:
1723                         ima_log_string(ab, "subj_user", args[0].from);
1724                         result = ima_lsm_rule_init(entry, args,
1725                                                    LSM_SUBJ_USER,
1726                                                    AUDIT_SUBJ_USER);
1727                         break;
1728                 case Opt_subj_role:
1729                         ima_log_string(ab, "subj_role", args[0].from);
1730                         result = ima_lsm_rule_init(entry, args,
1731                                                    LSM_SUBJ_ROLE,
1732                                                    AUDIT_SUBJ_ROLE);
1733                         break;
1734                 case Opt_subj_type:
1735                         ima_log_string(ab, "subj_type", args[0].from);
1736                         result = ima_lsm_rule_init(entry, args,
1737                                                    LSM_SUBJ_TYPE,
1738                                                    AUDIT_SUBJ_TYPE);
1739                         break;
1740                 case Opt_digest_type:
1741                         ima_log_string(ab, "digest_type", args[0].from);
1742                         if (entry->flags & IMA_DIGSIG_REQUIRED)
1743                                 result = -EINVAL;
1744                         else if ((strcmp(args[0].from, "verity")) == 0)
1745                                 entry->flags |= IMA_VERITY_REQUIRED;
1746                         else
1747                                 result = -EINVAL;
1748                         break;
1749                 case Opt_appraise_type:
1750                         ima_log_string(ab, "appraise_type", args[0].from);
1751
1752                         if ((strcmp(args[0].from, "imasig")) == 0) {
1753                                 if (entry->flags & IMA_VERITY_REQUIRED)
1754                                         result = -EINVAL;
1755                                 else
1756                                         entry->flags |= IMA_DIGSIG_REQUIRED;
1757                         } else if (strcmp(args[0].from, "sigv3") == 0) {
1758                                 /* Only fsverity supports sigv3 for now */
1759                                 if (entry->flags & IMA_VERITY_REQUIRED)
1760                                         entry->flags |= IMA_DIGSIG_REQUIRED;
1761                                 else
1762                                         result = -EINVAL;
1763                         } else if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) &&
1764                                  strcmp(args[0].from, "imasig|modsig") == 0) {
1765                                 if (entry->flags & IMA_VERITY_REQUIRED)
1766                                         result = -EINVAL;
1767                                 else
1768                                         entry->flags |= IMA_DIGSIG_REQUIRED |
1769                                                 IMA_MODSIG_ALLOWED;
1770                         } else {
1771                                 result = -EINVAL;
1772                         }
1773                         break;
1774                 case Opt_appraise_flag:
1775                         ima_log_string(ab, "appraise_flag", args[0].from);
1776                         if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) &&
1777                             strstr(args[0].from, "blacklist"))
1778                                 entry->flags |= IMA_CHECK_BLACKLIST;
1779                         else
1780                                 result = -EINVAL;
1781                         break;
1782                 case Opt_appraise_algos:
1783                         ima_log_string(ab, "appraise_algos", args[0].from);
1784
1785                         if (entry->allowed_algos) {
1786                                 result = -EINVAL;
1787                                 break;
1788                         }
1789
1790                         entry->allowed_algos =
1791                                 ima_parse_appraise_algos(args[0].from);
1792                         /* invalid or empty list of algorithms */
1793                         if (!entry->allowed_algos) {
1794                                 result = -EINVAL;
1795                                 break;
1796                         }
1797
1798                         entry->flags |= IMA_VALIDATE_ALGOS;
1799
1800                         break;
1801                 case Opt_permit_directio:
1802                         entry->flags |= IMA_PERMIT_DIRECTIO;
1803                         break;
1804                 case Opt_pcr:
1805                         ima_log_string(ab, "pcr", args[0].from);
1806
1807                         result = kstrtoint(args[0].from, 10, &entry->pcr);
1808                         if (result || INVALID_PCR(entry->pcr))
1809                                 result = -EINVAL;
1810                         else
1811                                 entry->flags |= IMA_PCR;
1812
1813                         break;
1814                 case Opt_template:
1815                         ima_log_string(ab, "template", args[0].from);
1816                         if (entry->action != MEASURE) {
1817                                 result = -EINVAL;
1818                                 break;
1819                         }
1820                         template_desc = lookup_template_desc(args[0].from);
1821                         if (!template_desc || entry->template) {
1822                                 result = -EINVAL;
1823                                 break;
1824                         }
1825
1826                         /*
1827                          * template_desc_init_fields() does nothing if
1828                          * the template is already initialised, so
1829                          * it's safe to do this unconditionally
1830                          */
1831                         template_desc_init_fields(template_desc->fmt,
1832                                                  &(template_desc->fields),
1833                                                  &(template_desc->num_fields));
1834                         entry->template = template_desc;
1835                         break;
1836                 case Opt_err:
1837                         ima_log_string(ab, "UNKNOWN", p);
1838                         result = -EINVAL;
1839                         break;
1840                 }
1841         }
1842         if (!result && !ima_validate_rule(entry))
1843                 result = -EINVAL;
1844         else if (entry->action == APPRAISE)
1845                 temp_ima_appraise |= ima_appraise_flag(entry->func);
1846
1847         if (!result && entry->flags & IMA_MODSIG_ALLOWED) {
1848                 template_desc = entry->template ? entry->template :
1849                                                   ima_template_desc_current();
1850                 check_template_modsig(template_desc);
1851         }
1852
1853         /* d-ngv2 template field recommended for unsigned fs-verity digests */
1854         if (!result && entry->action == MEASURE &&
1855             entry->flags & IMA_VERITY_REQUIRED) {
1856                 template_desc = entry->template ? entry->template :
1857                                                   ima_template_desc_current();
1858                 check_template_field(template_desc, "d-ngv2",
1859                                      "verity rules should include d-ngv2");
1860         }
1861
1862         audit_log_format(ab, "res=%d", !result);
1863         audit_log_end(ab);
1864         return result;
1865 }
1866
1867 /**
1868  * ima_parse_add_rule - add a rule to ima_policy_rules
1869  * @rule - ima measurement policy rule
1870  *
1871  * Avoid locking by allowing just one writer at a time in ima_write_policy()
1872  * Returns the length of the rule parsed, an error code on failure
1873  */
1874 ssize_t ima_parse_add_rule(char *rule)
1875 {
1876         static const char op[] = "update_policy";
1877         char *p;
1878         struct ima_rule_entry *entry;
1879         ssize_t result, len;
1880         int audit_info = 0;
1881
1882         p = strsep(&rule, "\n");
1883         len = strlen(p) + 1;
1884         p += strspn(p, " \t");
1885
1886         if (*p == '#' || *p == '\0')
1887                 return len;
1888
1889         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
1890         if (!entry) {
1891                 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
1892                                     NULL, op, "-ENOMEM", -ENOMEM, audit_info);
1893                 return -ENOMEM;
1894         }
1895
1896         INIT_LIST_HEAD(&entry->list);
1897
1898         result = ima_parse_rule(p, entry);
1899         if (result) {
1900                 ima_free_rule(entry);
1901                 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
1902                                     NULL, op, "invalid-policy", result,
1903                                     audit_info);
1904                 return result;
1905         }
1906
1907         list_add_tail(&entry->list, &ima_temp_rules);
1908
1909         return len;
1910 }
1911
1912 /**
1913  * ima_delete_rules() called to cleanup invalid in-flight policy.
1914  * We don't need locking as we operate on the temp list, which is
1915  * different from the active one.  There is also only one user of
1916  * ima_delete_rules() at a time.
1917  */
1918 void ima_delete_rules(void)
1919 {
1920         struct ima_rule_entry *entry, *tmp;
1921
1922         temp_ima_appraise = 0;
1923         list_for_each_entry_safe(entry, tmp, &ima_temp_rules, list) {
1924                 list_del(&entry->list);
1925                 ima_free_rule(entry);
1926         }
1927 }
1928
1929 #define __ima_hook_stringify(func, str) (#func),
1930
1931 const char *const func_tokens[] = {
1932         __ima_hooks(__ima_hook_stringify)
1933 };
1934
1935 #ifdef  CONFIG_IMA_READ_POLICY
1936 enum {
1937         mask_exec = 0, mask_write, mask_read, mask_append
1938 };
1939
1940 static const char *const mask_tokens[] = {
1941         "^MAY_EXEC",
1942         "^MAY_WRITE",
1943         "^MAY_READ",
1944         "^MAY_APPEND"
1945 };
1946
1947 void *ima_policy_start(struct seq_file *m, loff_t *pos)
1948 {
1949         loff_t l = *pos;
1950         struct ima_rule_entry *entry;
1951         struct list_head *ima_rules_tmp;
1952
1953         rcu_read_lock();
1954         ima_rules_tmp = rcu_dereference(ima_rules);
1955         list_for_each_entry_rcu(entry, ima_rules_tmp, list) {
1956                 if (!l--) {
1957                         rcu_read_unlock();
1958                         return entry;
1959                 }
1960         }
1961         rcu_read_unlock();
1962         return NULL;
1963 }
1964
1965 void *ima_policy_next(struct seq_file *m, void *v, loff_t *pos)
1966 {
1967         struct ima_rule_entry *entry = v;
1968
1969         rcu_read_lock();
1970         entry = list_entry_rcu(entry->list.next, struct ima_rule_entry, list);
1971         rcu_read_unlock();
1972         (*pos)++;
1973
1974         return (&entry->list == &ima_default_rules ||
1975                 &entry->list == &ima_policy_rules) ? NULL : entry;
1976 }
1977
1978 void ima_policy_stop(struct seq_file *m, void *v)
1979 {
1980 }
1981
1982 #define pt(token)       policy_tokens[token].pattern
1983 #define mt(token)       mask_tokens[token]
1984
1985 /*
1986  * policy_func_show - display the ima_hooks policy rule
1987  */
1988 static void policy_func_show(struct seq_file *m, enum ima_hooks func)
1989 {
1990         if (func > 0 && func < MAX_CHECK)
1991                 seq_printf(m, "func=%s ", func_tokens[func]);
1992         else
1993                 seq_printf(m, "func=%d ", func);
1994 }
1995
1996 static void ima_show_rule_opt_list(struct seq_file *m,
1997                                    const struct ima_rule_opt_list *opt_list)
1998 {
1999         size_t i;
2000
2001         for (i = 0; i < opt_list->count; i++)
2002                 seq_printf(m, "%s%s", i ? "|" : "", opt_list->items[i]);
2003 }
2004
2005 static void ima_policy_show_appraise_algos(struct seq_file *m,
2006                                            unsigned int allowed_hashes)
2007 {
2008         int idx, list_size = 0;
2009
2010         for (idx = 0; idx < HASH_ALGO__LAST; idx++) {
2011                 if (!(allowed_hashes & (1U << idx)))
2012                         continue;
2013
2014                 /* only add commas if the list contains multiple entries */
2015                 if (list_size++)
2016                         seq_puts(m, ",");
2017
2018                 seq_puts(m, hash_algo_name[idx]);
2019         }
2020 }
2021
2022 int ima_policy_show(struct seq_file *m, void *v)
2023 {
2024         struct ima_rule_entry *entry = v;
2025         int i;
2026         char tbuf[64] = {0,};
2027         int offset = 0;
2028
2029         rcu_read_lock();
2030
2031         /* Do not print rules with inactive LSM labels */
2032         for (i = 0; i < MAX_LSM_RULES; i++) {
2033                 if (entry->lsm[i].args_p && !entry->lsm[i].rule) {
2034                         rcu_read_unlock();
2035                         return 0;
2036                 }
2037         }
2038
2039         if (entry->action & MEASURE)
2040                 seq_puts(m, pt(Opt_measure));
2041         if (entry->action & DONT_MEASURE)
2042                 seq_puts(m, pt(Opt_dont_measure));
2043         if (entry->action & APPRAISE)
2044                 seq_puts(m, pt(Opt_appraise));
2045         if (entry->action & DONT_APPRAISE)
2046                 seq_puts(m, pt(Opt_dont_appraise));
2047         if (entry->action & AUDIT)
2048                 seq_puts(m, pt(Opt_audit));
2049         if (entry->action & HASH)
2050                 seq_puts(m, pt(Opt_hash));
2051         if (entry->action & DONT_HASH)
2052                 seq_puts(m, pt(Opt_dont_hash));
2053
2054         seq_puts(m, " ");
2055
2056         if (entry->flags & IMA_FUNC)
2057                 policy_func_show(m, entry->func);
2058
2059         if ((entry->flags & IMA_MASK) || (entry->flags & IMA_INMASK)) {
2060                 if (entry->flags & IMA_MASK)
2061                         offset = 1;
2062                 if (entry->mask & MAY_EXEC)
2063                         seq_printf(m, pt(Opt_mask), mt(mask_exec) + offset);
2064                 if (entry->mask & MAY_WRITE)
2065                         seq_printf(m, pt(Opt_mask), mt(mask_write) + offset);
2066                 if (entry->mask & MAY_READ)
2067                         seq_printf(m, pt(Opt_mask), mt(mask_read) + offset);
2068                 if (entry->mask & MAY_APPEND)
2069                         seq_printf(m, pt(Opt_mask), mt(mask_append) + offset);
2070                 seq_puts(m, " ");
2071         }
2072
2073         if (entry->flags & IMA_FSMAGIC) {
2074                 snprintf(tbuf, sizeof(tbuf), "0x%lx", entry->fsmagic);
2075                 seq_printf(m, pt(Opt_fsmagic), tbuf);
2076                 seq_puts(m, " ");
2077         }
2078
2079         if (entry->flags & IMA_FSNAME) {
2080                 snprintf(tbuf, sizeof(tbuf), "%s", entry->fsname);
2081                 seq_printf(m, pt(Opt_fsname), tbuf);
2082                 seq_puts(m, " ");
2083         }
2084
2085         if (entry->flags & IMA_KEYRINGS) {
2086                 seq_puts(m, "keyrings=");
2087                 ima_show_rule_opt_list(m, entry->keyrings);
2088                 seq_puts(m, " ");
2089         }
2090
2091         if (entry->flags & IMA_LABEL) {
2092                 seq_puts(m, "label=");
2093                 ima_show_rule_opt_list(m, entry->label);
2094                 seq_puts(m, " ");
2095         }
2096
2097         if (entry->flags & IMA_PCR) {
2098                 snprintf(tbuf, sizeof(tbuf), "%d", entry->pcr);
2099                 seq_printf(m, pt(Opt_pcr), tbuf);
2100                 seq_puts(m, " ");
2101         }
2102
2103         if (entry->flags & IMA_FSUUID) {
2104                 seq_printf(m, "fsuuid=%pU", &entry->fsuuid);
2105                 seq_puts(m, " ");
2106         }
2107
2108         if (entry->flags & IMA_UID) {
2109                 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
2110                 if (entry->uid_op == &uid_gt)
2111                         seq_printf(m, pt(Opt_uid_gt), tbuf);
2112                 else if (entry->uid_op == &uid_lt)
2113                         seq_printf(m, pt(Opt_uid_lt), tbuf);
2114                 else
2115                         seq_printf(m, pt(Opt_uid_eq), tbuf);
2116                 seq_puts(m, " ");
2117         }
2118
2119         if (entry->flags & IMA_EUID) {
2120                 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
2121                 if (entry->uid_op == &uid_gt)
2122                         seq_printf(m, pt(Opt_euid_gt), tbuf);
2123                 else if (entry->uid_op == &uid_lt)
2124                         seq_printf(m, pt(Opt_euid_lt), tbuf);
2125                 else
2126                         seq_printf(m, pt(Opt_euid_eq), tbuf);
2127                 seq_puts(m, " ");
2128         }
2129
2130         if (entry->flags & IMA_GID) {
2131                 snprintf(tbuf, sizeof(tbuf), "%d", __kgid_val(entry->gid));
2132                 if (entry->gid_op == &gid_gt)
2133                         seq_printf(m, pt(Opt_gid_gt), tbuf);
2134                 else if (entry->gid_op == &gid_lt)
2135                         seq_printf(m, pt(Opt_gid_lt), tbuf);
2136                 else
2137                         seq_printf(m, pt(Opt_gid_eq), tbuf);
2138                 seq_puts(m, " ");
2139         }
2140
2141         if (entry->flags & IMA_EGID) {
2142                 snprintf(tbuf, sizeof(tbuf), "%d", __kgid_val(entry->gid));
2143                 if (entry->gid_op == &gid_gt)
2144                         seq_printf(m, pt(Opt_egid_gt), tbuf);
2145                 else if (entry->gid_op == &gid_lt)
2146                         seq_printf(m, pt(Opt_egid_lt), tbuf);
2147                 else
2148                         seq_printf(m, pt(Opt_egid_eq), tbuf);
2149                 seq_puts(m, " ");
2150         }
2151
2152         if (entry->flags & IMA_FOWNER) {
2153                 snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->fowner));
2154                 if (entry->fowner_op == &uid_gt)
2155                         seq_printf(m, pt(Opt_fowner_gt), tbuf);
2156                 else if (entry->fowner_op == &uid_lt)
2157                         seq_printf(m, pt(Opt_fowner_lt), tbuf);
2158                 else
2159                         seq_printf(m, pt(Opt_fowner_eq), tbuf);
2160                 seq_puts(m, " ");
2161         }
2162
2163         if (entry->flags & IMA_FGROUP) {
2164                 snprintf(tbuf, sizeof(tbuf), "%d", __kgid_val(entry->fgroup));
2165                 if (entry->fgroup_op == &gid_gt)
2166                         seq_printf(m, pt(Opt_fgroup_gt), tbuf);
2167                 else if (entry->fgroup_op == &gid_lt)
2168                         seq_printf(m, pt(Opt_fgroup_lt), tbuf);
2169                 else
2170                         seq_printf(m, pt(Opt_fgroup_eq), tbuf);
2171                 seq_puts(m, " ");
2172         }
2173
2174         if (entry->flags & IMA_VALIDATE_ALGOS) {
2175                 seq_puts(m, "appraise_algos=");
2176                 ima_policy_show_appraise_algos(m, entry->allowed_algos);
2177                 seq_puts(m, " ");
2178         }
2179
2180         for (i = 0; i < MAX_LSM_RULES; i++) {
2181                 if (entry->lsm[i].rule) {
2182                         switch (i) {
2183                         case LSM_OBJ_USER:
2184                                 seq_printf(m, pt(Opt_obj_user),
2185                                            entry->lsm[i].args_p);
2186                                 break;
2187                         case LSM_OBJ_ROLE:
2188                                 seq_printf(m, pt(Opt_obj_role),
2189                                            entry->lsm[i].args_p);
2190                                 break;
2191                         case LSM_OBJ_TYPE:
2192                                 seq_printf(m, pt(Opt_obj_type),
2193                                            entry->lsm[i].args_p);
2194                                 break;
2195                         case LSM_SUBJ_USER:
2196                                 seq_printf(m, pt(Opt_subj_user),
2197                                            entry->lsm[i].args_p);
2198                                 break;
2199                         case LSM_SUBJ_ROLE:
2200                                 seq_printf(m, pt(Opt_subj_role),
2201                                            entry->lsm[i].args_p);
2202                                 break;
2203                         case LSM_SUBJ_TYPE:
2204                                 seq_printf(m, pt(Opt_subj_type),
2205                                            entry->lsm[i].args_p);
2206                                 break;
2207                         }
2208                         seq_puts(m, " ");
2209                 }
2210         }
2211         if (entry->template)
2212                 seq_printf(m, "template=%s ", entry->template->name);
2213         if (entry->flags & IMA_DIGSIG_REQUIRED) {
2214                 if (entry->flags & IMA_VERITY_REQUIRED)
2215                         seq_puts(m, "appraise_type=sigv3 ");
2216                 else if (entry->flags & IMA_MODSIG_ALLOWED)
2217                         seq_puts(m, "appraise_type=imasig|modsig ");
2218                 else
2219                         seq_puts(m, "appraise_type=imasig ");
2220         }
2221         if (entry->flags & IMA_VERITY_REQUIRED)
2222                 seq_puts(m, "digest_type=verity ");
2223         if (entry->flags & IMA_CHECK_BLACKLIST)
2224                 seq_puts(m, "appraise_flag=check_blacklist ");
2225         if (entry->flags & IMA_PERMIT_DIRECTIO)
2226                 seq_puts(m, "permit_directio ");
2227         rcu_read_unlock();
2228         seq_puts(m, "\n");
2229         return 0;
2230 }
2231 #endif  /* CONFIG_IMA_READ_POLICY */
2232
2233 #if defined(CONFIG_IMA_APPRAISE) && defined(CONFIG_INTEGRITY_TRUSTED_KEYRING)
2234 /*
2235  * ima_appraise_signature: whether IMA will appraise a given function using
2236  * an IMA digital signature. This is restricted to cases where the kernel
2237  * has a set of built-in trusted keys in order to avoid an attacker simply
2238  * loading additional keys.
2239  */
2240 bool ima_appraise_signature(enum kernel_read_file_id id)
2241 {
2242         struct ima_rule_entry *entry;
2243         bool found = false;
2244         enum ima_hooks func;
2245         struct list_head *ima_rules_tmp;
2246
2247         if (id >= READING_MAX_ID)
2248                 return false;
2249
2250         if (id == READING_KEXEC_IMAGE && !(ima_appraise & IMA_APPRAISE_ENFORCE)
2251             && security_locked_down(LOCKDOWN_KEXEC))
2252                 return false;
2253
2254         func = read_idmap[id] ?: FILE_CHECK;
2255
2256         rcu_read_lock();
2257         ima_rules_tmp = rcu_dereference(ima_rules);
2258         list_for_each_entry_rcu(entry, ima_rules_tmp, list) {
2259                 if (entry->action != APPRAISE)
2260                         continue;
2261
2262                 /*
2263                  * A generic entry will match, but otherwise require that it
2264                  * match the func we're looking for
2265                  */
2266                 if (entry->func && entry->func != func)
2267                         continue;
2268
2269                 /*
2270                  * We require this to be a digital signature, not a raw IMA
2271                  * hash.
2272                  */
2273                 if (entry->flags & IMA_DIGSIG_REQUIRED)
2274                         found = true;
2275
2276                 /*
2277                  * We've found a rule that matches, so break now even if it
2278                  * didn't require a digital signature - a later rule that does
2279                  * won't override it, so would be a false positive.
2280                  */
2281                 break;
2282         }
2283
2284         rcu_read_unlock();
2285         return found;
2286 }
2287 #endif /* CONFIG_IMA_APPRAISE && CONFIG_INTEGRITY_TRUSTED_KEYRING */