1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* System trusted keyring for trusted public keys 3 * 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 20 static struct key *builtin_trusted_keys; 21 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 22 static struct key *secondary_trusted_keys; 23 #endif 24 #ifdef CONFIG_INTEGRITY_MACHINE_KEYRING 25 static struct key *machine_trusted_keys; 26 #endif 27 #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING 28 static struct key *platform_trusted_keys; 29 #endif 30 31 extern __initconst const u8 system_certificate_list[]; 32 extern __initconst const unsigned long system_certificate_list_size; 33 extern __initconst const unsigned long module_cert_size; 34 35 /** 36 * restrict_link_by_builtin_trusted - Restrict keyring addition by built-in CA 37 * @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-added 43 * being vouched for by a key in the built in system keyring. 44 */ 45 int 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 keyring 56 * @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-added 62 * being vouched for by a key in the built in system keyring. The new key 63 * must have the digitalSignature usage field set. 64 */ 65 int 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_KEYRING 75 /** 76 * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring 77 * 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-added 84 * being vouched for by a key in either the built-in or the secondary system 85 * keyrings. 86 */ 87 int 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 link 94 * 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-added 114 * being vouched for by a key in either the built-in or the secondary system 115 * keyrings. The new key must have the digitalSignature usage field set. 116 */ 117 int 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 link 123 * 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 */ 139 static __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 else 151 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 key 159 * @data: The blob holding the key 160 * @len: The length of the data blob 161 * 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 */ 165 void __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 #endif 186 #ifdef CONFIG_INTEGRITY_MACHINE_KEYRING 187 void __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-added 203 * being vouched for by a key in either the built-in, the secondary, or 204 * the machine keyrings. 205 */ 206 int 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 #endif 222 223 /* 224 * Create the trusted keyrings 225 */ 226 static __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_KEYRING 241 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 #endif 256 257 return 0; 258 } 259 260 /* 261 * Must be initialised before we try and load the keys into the keyring. 262 */ 263 device_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 */ 279 static __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_SIG 287 p = system_certificate_list; 288 size = system_certificate_list_size; 289 #else 290 p = system_certificate_list + module_cert_size; 291 size = system_certificate_list_size - module_cert_size; 292 #endif 293 294 return x509_load_certificate_list(p, size, builtin_trusted_keys); 295 } 296 late_initcall(load_system_certificate_list); 297 298 #ifdef CONFIG_SYSTEM_DATA_VERIFICATION 299 300 /** 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 */ 311 int 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_KEYRING 343 trusted_keys = secondary_trusted_keys; 344 #else 345 trusted_keys = builtin_trusted_keys; 346 #endif 347 } else if (trusted_keys == VERIFY_USE_PLATFORM_KEYRING) { 348 #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING 349 trusted_keys = platform_trusted_keys; 350 #else 351 trusted_keys = NULL; 352 #endif 353 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 } 378 379 error: 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 */ 396 int 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 } 419 EXPORT_SYMBOL_GPL(verify_pkcs7_signature); 420 421 #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ 422 423 #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING 424 void __init set_platform_trusted_keys(struct key *keyring) 425 { 426 platform_trusted_keys = keyring; 427 } 428 #endif 429