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 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 55 /** 56 * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring 57 * addition by both built-in and secondary keyrings. 58 * @dest_keyring: Keyring being linked to. 59 * @type: The type of key being added. 60 * @payload: The payload of the new key. 61 * @restrict_key: A ring of keys that can be used to vouch for the new cert. 62 * 63 * Restrict the addition of keys into a keyring based on the key-to-be-added 64 * being vouched for by a key in either the built-in or the secondary system 65 * keyrings. 66 */ 67 int restrict_link_by_builtin_and_secondary_trusted( 68 struct key *dest_keyring, 69 const struct key_type *type, 70 const union key_payload *payload, 71 struct key *restrict_key) 72 { 73 /* If we have a secondary trusted keyring, then that contains a link 74 * through to the builtin keyring and the search will follow that link. 75 */ 76 if (type == &key_type_keyring && 77 dest_keyring == secondary_trusted_keys && 78 payload == &builtin_trusted_keys->payload) 79 /* Allow the builtin keyring to be added to the secondary */ 80 return 0; 81 82 return restrict_link_by_signature(dest_keyring, type, payload, 83 secondary_trusted_keys); 84 } 85 86 /* 87 * Allocate a struct key_restriction for the "builtin and secondary trust" 88 * keyring. Only for use in system_trusted_keyring_init(). 89 */ 90 static __init struct key_restriction *get_builtin_and_secondary_restriction(void) 91 { 92 struct key_restriction *restriction; 93 94 restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL); 95 96 if (!restriction) 97 panic("Can't allocate secondary trusted keyring restriction\n"); 98 99 if (IS_ENABLED(CONFIG_INTEGRITY_MACHINE_KEYRING)) 100 restriction->check = restrict_link_by_builtin_secondary_and_machine; 101 else 102 restriction->check = restrict_link_by_builtin_and_secondary_trusted; 103 104 return restriction; 105 } 106 #endif 107 #ifdef CONFIG_INTEGRITY_MACHINE_KEYRING 108 void __init set_machine_trusted_keys(struct key *keyring) 109 { 110 machine_trusted_keys = keyring; 111 112 if (key_link(secondary_trusted_keys, machine_trusted_keys) < 0) 113 panic("Can't link (machine) trusted keyrings\n"); 114 } 115 116 /** 117 * restrict_link_by_builtin_secondary_and_machine - Restrict keyring addition. 118 * @dest_keyring: Keyring being linked to. 119 * @type: The type of key being added. 120 * @payload: The payload of the new key. 121 * @restrict_key: A ring of keys that can be used to vouch for the new cert. 122 * 123 * Restrict the addition of keys into a keyring based on the key-to-be-added 124 * being vouched for by a key in either the built-in, the secondary, or 125 * the machine keyrings. 126 */ 127 int restrict_link_by_builtin_secondary_and_machine( 128 struct key *dest_keyring, 129 const struct key_type *type, 130 const union key_payload *payload, 131 struct key *restrict_key) 132 { 133 if (machine_trusted_keys && type == &key_type_keyring && 134 dest_keyring == secondary_trusted_keys && 135 payload == &machine_trusted_keys->payload) 136 /* Allow the machine keyring to be added to the secondary */ 137 return 0; 138 139 return restrict_link_by_builtin_and_secondary_trusted(dest_keyring, type, 140 payload, restrict_key); 141 } 142 #endif 143 144 /* 145 * Create the trusted keyrings 146 */ 147 static __init int system_trusted_keyring_init(void) 148 { 149 pr_notice("Initialise system trusted keyrings\n"); 150 151 builtin_trusted_keys = 152 keyring_alloc(".builtin_trusted_keys", 153 GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(), 154 ((KEY_POS_ALL & ~KEY_POS_SETATTR) | 155 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH), 156 KEY_ALLOC_NOT_IN_QUOTA, 157 NULL, NULL); 158 if (IS_ERR(builtin_trusted_keys)) 159 panic("Can't allocate builtin trusted keyring\n"); 160 161 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 162 secondary_trusted_keys = 163 keyring_alloc(".secondary_trusted_keys", 164 GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(), 165 ((KEY_POS_ALL & ~KEY_POS_SETATTR) | 166 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH | 167 KEY_USR_WRITE), 168 KEY_ALLOC_NOT_IN_QUOTA, 169 get_builtin_and_secondary_restriction(), 170 NULL); 171 if (IS_ERR(secondary_trusted_keys)) 172 panic("Can't allocate secondary trusted keyring\n"); 173 174 if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0) 175 panic("Can't link trusted keyrings\n"); 176 #endif 177 178 return 0; 179 } 180 181 /* 182 * Must be initialised before we try and load the keys into the keyring. 183 */ 184 device_initcall(system_trusted_keyring_init); 185 186 __init int load_module_cert(struct key *keyring) 187 { 188 if (!IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG)) 189 return 0; 190 191 pr_notice("Loading compiled-in module X.509 certificates\n"); 192 193 return x509_load_certificate_list(system_certificate_list, 194 module_cert_size, keyring); 195 } 196 197 /* 198 * Load the compiled-in list of X.509 certificates. 199 */ 200 static __init int load_system_certificate_list(void) 201 { 202 const u8 *p; 203 unsigned long size; 204 205 pr_notice("Loading compiled-in X.509 certificates\n"); 206 207 #ifdef CONFIG_MODULE_SIG 208 p = system_certificate_list; 209 size = system_certificate_list_size; 210 #else 211 p = system_certificate_list + module_cert_size; 212 size = system_certificate_list_size - module_cert_size; 213 #endif 214 215 return x509_load_certificate_list(p, size, builtin_trusted_keys); 216 } 217 late_initcall(load_system_certificate_list); 218 219 #ifdef CONFIG_SYSTEM_DATA_VERIFICATION 220 221 /** 222 * verify_pkcs7_message_sig - Verify a PKCS#7-based signature on system data. 223 * @data: The data to be verified (NULL if expecting internal data). 224 * @len: Size of @data. 225 * @pkcs7: The PKCS#7 message that is the signature. 226 * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, 227 * (void *)1UL for all trusted keys). 228 * @usage: The use to which the key is being put. 229 * @view_content: Callback to gain access to content. 230 * @ctx: Context for callback. 231 */ 232 int verify_pkcs7_message_sig(const void *data, size_t len, 233 struct pkcs7_message *pkcs7, 234 struct key *trusted_keys, 235 enum key_being_used_for usage, 236 int (*view_content)(void *ctx, 237 const void *data, size_t len, 238 size_t asn1hdrlen), 239 void *ctx) 240 { 241 int ret; 242 243 /* The data should be detached - so we need to supply it. */ 244 if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) { 245 pr_err("PKCS#7 signature with non-detached data\n"); 246 ret = -EBADMSG; 247 goto error; 248 } 249 250 ret = pkcs7_verify(pkcs7, usage); 251 if (ret < 0) 252 goto error; 253 254 if (!trusted_keys) { 255 trusted_keys = builtin_trusted_keys; 256 } else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) { 257 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 258 trusted_keys = secondary_trusted_keys; 259 #else 260 trusted_keys = builtin_trusted_keys; 261 #endif 262 } else if (trusted_keys == VERIFY_USE_PLATFORM_KEYRING) { 263 #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING 264 trusted_keys = platform_trusted_keys; 265 #else 266 trusted_keys = NULL; 267 #endif 268 if (!trusted_keys) { 269 ret = -ENOKEY; 270 pr_devel("PKCS#7 platform keyring is not available\n"); 271 goto error; 272 } 273 274 ret = is_key_on_revocation_list(pkcs7); 275 if (ret != -ENOKEY) { 276 pr_devel("PKCS#7 platform key is on revocation list\n"); 277 goto error; 278 } 279 } 280 ret = pkcs7_validate_trust(pkcs7, trusted_keys); 281 if (ret < 0) { 282 if (ret == -ENOKEY) 283 pr_devel("PKCS#7 signature not signed with a trusted key\n"); 284 goto error; 285 } 286 287 if (view_content) { 288 size_t asn1hdrlen; 289 290 ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen); 291 if (ret < 0) { 292 if (ret == -ENODATA) 293 pr_devel("PKCS#7 message does not contain data\n"); 294 goto error; 295 } 296 297 ret = view_content(ctx, data, len, asn1hdrlen); 298 } 299 300 error: 301 pr_devel("<==%s() = %d\n", __func__, ret); 302 return ret; 303 } 304 305 /** 306 * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. 307 * @data: The data to be verified (NULL if expecting internal data). 308 * @len: Size of @data. 309 * @raw_pkcs7: The PKCS#7 message that is the signature. 310 * @pkcs7_len: The size of @raw_pkcs7. 311 * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, 312 * (void *)1UL for all trusted keys). 313 * @usage: The use to which the key is being put. 314 * @view_content: Callback to gain access to content. 315 * @ctx: Context for callback. 316 */ 317 int verify_pkcs7_signature(const void *data, size_t len, 318 const void *raw_pkcs7, size_t pkcs7_len, 319 struct key *trusted_keys, 320 enum key_being_used_for usage, 321 int (*view_content)(void *ctx, 322 const void *data, size_t len, 323 size_t asn1hdrlen), 324 void *ctx) 325 { 326 struct pkcs7_message *pkcs7; 327 int ret; 328 329 pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); 330 if (IS_ERR(pkcs7)) 331 return PTR_ERR(pkcs7); 332 333 ret = verify_pkcs7_message_sig(data, len, pkcs7, trusted_keys, usage, 334 view_content, ctx); 335 336 pkcs7_free_message(pkcs7); 337 pr_devel("<==%s() = %d\n", __func__, ret); 338 return ret; 339 } 340 EXPORT_SYMBOL_GPL(verify_pkcs7_signature); 341 342 #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ 343 344 #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING 345 void __init set_platform_trusted_keys(struct key *keyring) 346 { 347 platform_trusted_keys = keyring; 348 } 349 #endif 350