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