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1// SPDX-License-Identifier: GPL-2.0-or-later2/* System trusted keyring for trusted public keys3 *4 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.5 * Written by David Howells (dhowells@redhat.com)6 */7 8#include <linux/export.h>9#include <linux/kernel.h>10#include <linux/sched.h>11#include <linux/cred.h>12#include <linux/err.h>13#include <linux/slab.h>14#include <linux/uidgid.h>15#include <linux/verification.h>16#include <keys/asymmetric-type.h>17#include <keys/system_keyring.h>18#include <crypto/pkcs7.h>19 20static struct key *builtin_trusted_keys;21#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING22static struct key *secondary_trusted_keys;23#endif24#ifdef CONFIG_INTEGRITY_MACHINE_KEYRING25static struct key *machine_trusted_keys;26#endif27#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING28static struct key *platform_trusted_keys;29#endif30 31extern __initconst const u8 system_certificate_list[];32extern __initconst const unsigned long system_certificate_list_size;33extern __initconst const unsigned long module_cert_size;34 35/**36 * restrict_link_by_builtin_trusted - Restrict keyring addition by built-in CA37 * @dest_keyring: Keyring being linked to.38 * @type: The type of key being added.39 * @payload: The payload of the new key.40 * @restriction_key: A ring of keys that can be used to vouch for the new cert.41 *42 * Restrict the addition of keys into a keyring based on the key-to-be-added43 * being vouched for by a key in the built in system keyring.44 */45int restrict_link_by_builtin_trusted(struct key *dest_keyring,46 const struct key_type *type,47 const union key_payload *payload,48 struct key *restriction_key)49{50 return restrict_link_by_signature(dest_keyring, type, payload,51 builtin_trusted_keys);52}53 54/**55 * restrict_link_by_digsig_builtin - Restrict digitalSignature key additions by the built-in keyring56 * @dest_keyring: Keyring being linked to.57 * @type: The type of key being added.58 * @payload: The payload of the new key.59 * @restriction_key: A ring of keys that can be used to vouch for the new cert.60 *61 * Restrict the addition of keys into a keyring based on the key-to-be-added62 * being vouched for by a key in the built in system keyring. The new key63 * must have the digitalSignature usage field set.64 */65int restrict_link_by_digsig_builtin(struct key *dest_keyring,66 const struct key_type *type,67 const union key_payload *payload,68 struct key *restriction_key)69{70 return restrict_link_by_digsig(dest_keyring, type, payload,71 builtin_trusted_keys);72}73 74#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING75/**76 * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring77 * addition by both built-in and secondary keyrings.78 * @dest_keyring: Keyring being linked to.79 * @type: The type of key being added.80 * @payload: The payload of the new key.81 * @restrict_key: A ring of keys that can be used to vouch for the new cert.82 *83 * Restrict the addition of keys into a keyring based on the key-to-be-added84 * being vouched for by a key in either the built-in or the secondary system85 * keyrings.86 */87int restrict_link_by_builtin_and_secondary_trusted(88 struct key *dest_keyring,89 const struct key_type *type,90 const union key_payload *payload,91 struct key *restrict_key)92{93 /* If we have a secondary trusted keyring, then that contains a link94 * through to the builtin keyring and the search will follow that link.95 */96 if (type == &key_type_keyring &&97 dest_keyring == secondary_trusted_keys &&98 payload == &builtin_trusted_keys->payload)99 /* Allow the builtin keyring to be added to the secondary */100 return 0;101 102 return restrict_link_by_signature(dest_keyring, type, payload,103 secondary_trusted_keys);104}105 106/**107 * restrict_link_by_digsig_builtin_and_secondary - Restrict by digitalSignature.108 * @dest_keyring: Keyring being linked to.109 * @type: The type of key being added.110 * @payload: The payload of the new key.111 * @restrict_key: A ring of keys that can be used to vouch for the new cert.112 *113 * Restrict the addition of keys into a keyring based on the key-to-be-added114 * being vouched for by a key in either the built-in or the secondary system115 * keyrings. The new key must have the digitalSignature usage field set.116 */117int restrict_link_by_digsig_builtin_and_secondary(struct key *dest_keyring,118 const struct key_type *type,119 const union key_payload *payload,120 struct key *restrict_key)121{122 /* If we have a secondary trusted keyring, then that contains a link123 * through to the builtin keyring and the search will follow that link.124 */125 if (type == &key_type_keyring &&126 dest_keyring == secondary_trusted_keys &&127 payload == &builtin_trusted_keys->payload)128 /* Allow the builtin keyring to be added to the secondary */129 return 0;130 131 return restrict_link_by_digsig(dest_keyring, type, payload,132 secondary_trusted_keys);133}134 135/*136 * Allocate a struct key_restriction for the "builtin and secondary trust"137 * keyring. Only for use in system_trusted_keyring_init().138 */139static __init struct key_restriction *get_builtin_and_secondary_restriction(void)140{141 struct key_restriction *restriction;142 143 restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);144 145 if (!restriction)146 panic("Can't allocate secondary trusted keyring restriction\n");147 148 if (IS_ENABLED(CONFIG_INTEGRITY_MACHINE_KEYRING))149 restriction->check = restrict_link_by_builtin_secondary_and_machine;150 else151 restriction->check = restrict_link_by_builtin_and_secondary_trusted;152 153 return restriction;154}155 156/**157 * add_to_secondary_keyring - Add to secondary keyring.158 * @source: Source of key159 * @data: The blob holding the key160 * @len: The length of the data blob161 *162 * Add a key to the secondary keyring. The key must be vouched for by a key in the builtin,163 * machine or secondary keyring itself.164 */165void __init add_to_secondary_keyring(const char *source, const void *data, size_t len)166{167 key_ref_t key;168 key_perm_t perm;169 170 perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW;171 172 key = key_create_or_update(make_key_ref(secondary_trusted_keys, 1),173 "asymmetric",174 NULL, data, len, perm,175 KEY_ALLOC_NOT_IN_QUOTA);176 if (IS_ERR(key)) {177 pr_err("Problem loading X.509 certificate from %s to secondary keyring %ld\n",178 source, PTR_ERR(key));179 return;180 }181 182 pr_notice("Loaded X.509 cert '%s'\n", key_ref_to_ptr(key)->description);183 key_ref_put(key);184}185#endif186#ifdef CONFIG_INTEGRITY_MACHINE_KEYRING187void __init set_machine_trusted_keys(struct key *keyring)188{189 machine_trusted_keys = keyring;190 191 if (key_link(secondary_trusted_keys, machine_trusted_keys) < 0)192 panic("Can't link (machine) trusted keyrings\n");193}194 195/**196 * restrict_link_by_builtin_secondary_and_machine - Restrict keyring addition.197 * @dest_keyring: Keyring being linked to.198 * @type: The type of key being added.199 * @payload: The payload of the new key.200 * @restrict_key: A ring of keys that can be used to vouch for the new cert.201 *202 * Restrict the addition of keys into a keyring based on the key-to-be-added203 * being vouched for by a key in either the built-in, the secondary, or204 * the machine keyrings.205 */206int restrict_link_by_builtin_secondary_and_machine(207 struct key *dest_keyring,208 const struct key_type *type,209 const union key_payload *payload,210 struct key *restrict_key)211{212 if (machine_trusted_keys && type == &key_type_keyring &&213 dest_keyring == secondary_trusted_keys &&214 payload == &machine_trusted_keys->payload)215 /* Allow the machine keyring to be added to the secondary */216 return 0;217 218 return restrict_link_by_builtin_and_secondary_trusted(dest_keyring, type,219 payload, restrict_key);220}221#endif222 223/*224 * Create the trusted keyrings225 */226static __init int system_trusted_keyring_init(void)227{228 pr_notice("Initialise system trusted keyrings\n");229 230 builtin_trusted_keys =231 keyring_alloc(".builtin_trusted_keys",232 GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(),233 ((KEY_POS_ALL & ~KEY_POS_SETATTR) |234 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH),235 KEY_ALLOC_NOT_IN_QUOTA,236 NULL, NULL);237 if (IS_ERR(builtin_trusted_keys))238 panic("Can't allocate builtin trusted keyring\n");239 240#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING241 secondary_trusted_keys =242 keyring_alloc(".secondary_trusted_keys",243 GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(),244 ((KEY_POS_ALL & ~KEY_POS_SETATTR) |245 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH |246 KEY_USR_WRITE),247 KEY_ALLOC_NOT_IN_QUOTA,248 get_builtin_and_secondary_restriction(),249 NULL);250 if (IS_ERR(secondary_trusted_keys))251 panic("Can't allocate secondary trusted keyring\n");252 253 if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0)254 panic("Can't link trusted keyrings\n");255#endif256 257 return 0;258}259 260/*261 * Must be initialised before we try and load the keys into the keyring.262 */263device_initcall(system_trusted_keyring_init);264 265__init int load_module_cert(struct key *keyring)266{267 if (!IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG))268 return 0;269 270 pr_notice("Loading compiled-in module X.509 certificates\n");271 272 return x509_load_certificate_list(system_certificate_list,273 module_cert_size, keyring);274}275 276/*277 * Load the compiled-in list of X.509 certificates.278 */279static __init int load_system_certificate_list(void)280{281 const u8 *p;282 unsigned long size;283 284 pr_notice("Loading compiled-in X.509 certificates\n");285 286#ifdef CONFIG_MODULE_SIG287 p = system_certificate_list;288 size = system_certificate_list_size;289#else290 p = system_certificate_list + module_cert_size;291 size = system_certificate_list_size - module_cert_size;292#endif293 294 return x509_load_certificate_list(p, size, builtin_trusted_keys);295}296late_initcall(load_system_certificate_list);297 298#ifdef CONFIG_SYSTEM_DATA_VERIFICATION299 300/**301 * verify_pkcs7_message_sig - Verify a PKCS#7-based signature on system data.302 * @data: The data to be verified (NULL if expecting internal data).303 * @len: Size of @data.304 * @pkcs7: The PKCS#7 message that is the signature.305 * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only,306 * (void *)1UL for all trusted keys).307 * @usage: The use to which the key is being put.308 * @view_content: Callback to gain access to content.309 * @ctx: Context for callback.310 */311int verify_pkcs7_message_sig(const void *data, size_t len,312 struct pkcs7_message *pkcs7,313 struct key *trusted_keys,314 enum key_being_used_for usage,315 int (*view_content)(void *ctx,316 const void *data, size_t len,317 size_t asn1hdrlen),318 void *ctx)319{320 int ret;321 322 /* The data should be detached - so we need to supply it. */323 if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) {324 pr_err("PKCS#7 signature with non-detached data\n");325 ret = -EBADMSG;326 goto error;327 }328 329 ret = pkcs7_verify(pkcs7, usage);330 if (ret < 0)331 goto error;332 333 ret = is_key_on_revocation_list(pkcs7);334 if (ret != -ENOKEY) {335 pr_devel("PKCS#7 key is on revocation list\n");336 goto error;337 }338 339 if (!trusted_keys) {340 trusted_keys = builtin_trusted_keys;341 } else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) {342#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING343 trusted_keys = secondary_trusted_keys;344#else345 trusted_keys = builtin_trusted_keys;346#endif347 } else if (trusted_keys == VERIFY_USE_PLATFORM_KEYRING) {348#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING349 trusted_keys = platform_trusted_keys;350#else351 trusted_keys = NULL;352#endif353 if (!trusted_keys) {354 ret = -ENOKEY;355 pr_devel("PKCS#7 platform keyring is not available\n");356 goto error;357 }358 }359 ret = pkcs7_validate_trust(pkcs7, trusted_keys);360 if (ret < 0) {361 if (ret == -ENOKEY)362 pr_devel("PKCS#7 signature not signed with a trusted key\n");363 goto error;364 }365 366 if (view_content) {367 size_t asn1hdrlen;368 369 ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen);370 if (ret < 0) {371 if (ret == -ENODATA)372 pr_devel("PKCS#7 message does not contain data\n");373 goto error;374 }375 376 ret = view_content(ctx, data, len, asn1hdrlen);377 }378 379error:380 pr_devel("<==%s() = %d\n", __func__, ret);381 return ret;382}383 384/**385 * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data.386 * @data: The data to be verified (NULL if expecting internal data).387 * @len: Size of @data.388 * @raw_pkcs7: The PKCS#7 message that is the signature.389 * @pkcs7_len: The size of @raw_pkcs7.390 * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only,391 * (void *)1UL for all trusted keys).392 * @usage: The use to which the key is being put.393 * @view_content: Callback to gain access to content.394 * @ctx: Context for callback.395 */396int verify_pkcs7_signature(const void *data, size_t len,397 const void *raw_pkcs7, size_t pkcs7_len,398 struct key *trusted_keys,399 enum key_being_used_for usage,400 int (*view_content)(void *ctx,401 const void *data, size_t len,402 size_t asn1hdrlen),403 void *ctx)404{405 struct pkcs7_message *pkcs7;406 int ret;407 408 pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);409 if (IS_ERR(pkcs7))410 return PTR_ERR(pkcs7);411 412 ret = verify_pkcs7_message_sig(data, len, pkcs7, trusted_keys, usage,413 view_content, ctx);414 415 pkcs7_free_message(pkcs7);416 pr_devel("<==%s() = %d\n", __func__, ret);417 return ret;418}419EXPORT_SYMBOL_GPL(verify_pkcs7_signature);420 421#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */422 423#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING424void __init set_platform_trusted_keys(struct key *keyring)425{426 platform_trusted_keys = keyring;427}428#endif429