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_to_builtin_trusted - Restrict keyring addition by built in CA 37 * 38 * Restrict the addition of keys into a keyring based on the key-to-be-added 39 * being vouched for by a key in the built in system keyring. 40 */ 41 int restrict_link_by_builtin_trusted(struct key *dest_keyring, 42 const struct key_type *type, 43 const union key_payload *payload, 44 struct key *restriction_key) 45 { 46 return restrict_link_by_signature(dest_keyring, type, payload, 47 builtin_trusted_keys); 48 } 49 50 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 51 /** 52 * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring 53 * addition by both builtin and secondary keyrings 54 * 55 * Restrict the addition of keys into a keyring based on the key-to-be-added 56 * being vouched for by a key in either the built-in or the secondary system 57 * keyrings. 58 */ 59 int restrict_link_by_builtin_and_secondary_trusted( 60 struct key *dest_keyring, 61 const struct key_type *type, 62 const union key_payload *payload, 63 struct key *restrict_key) 64 { 65 /* If we have a secondary trusted keyring, then that contains a link 66 * through to the builtin keyring and the search will follow that link. 67 */ 68 if (type == &key_type_keyring && 69 dest_keyring == secondary_trusted_keys && 70 payload == &builtin_trusted_keys->payload) 71 /* Allow the builtin keyring to be added to the secondary */ 72 return 0; 73 74 return restrict_link_by_signature(dest_keyring, type, payload, 75 secondary_trusted_keys); 76 } 77 78 /** 79 * Allocate a struct key_restriction for the "builtin and secondary trust" 80 * keyring. Only for use in system_trusted_keyring_init(). 81 */ 82 static __init struct key_restriction *get_builtin_and_secondary_restriction(void) 83 { 84 struct key_restriction *restriction; 85 86 restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL); 87 88 if (!restriction) 89 panic("Can't allocate secondary trusted keyring restriction\n"); 90 91 if (IS_ENABLED(CONFIG_INTEGRITY_MACHINE_KEYRING)) 92 restriction->check = restrict_link_by_builtin_secondary_and_machine; 93 else 94 restriction->check = restrict_link_by_builtin_and_secondary_trusted; 95 96 return restriction; 97 } 98 #endif 99 #ifdef CONFIG_INTEGRITY_MACHINE_KEYRING 100 void __init set_machine_trusted_keys(struct key *keyring) 101 { 102 machine_trusted_keys = keyring; 103 104 if (key_link(secondary_trusted_keys, machine_trusted_keys) < 0) 105 panic("Can't link (machine) trusted keyrings\n"); 106 } 107 108 /** 109 * restrict_link_by_builtin_secondary_and_machine - Restrict keyring addition. 110 * @dest_keyring: Keyring being linked to. 111 * @type: The type of key being added. 112 * @payload: The payload of the new key. 113 * @restrict_key: A ring of keys that can be used to vouch for the new cert. 114 * 115 * Restrict the addition of keys into a keyring based on the key-to-be-added 116 * being vouched for by a key in either the built-in, the secondary, or 117 * the machine keyrings. 118 */ 119 int restrict_link_by_builtin_secondary_and_machine( 120 struct key *dest_keyring, 121 const struct key_type *type, 122 const union key_payload *payload, 123 struct key *restrict_key) 124 { 125 if (machine_trusted_keys && type == &key_type_keyring && 126 dest_keyring == secondary_trusted_keys && 127 payload == &machine_trusted_keys->payload) 128 /* Allow the machine keyring to be added to the secondary */ 129 return 0; 130 131 return restrict_link_by_builtin_and_secondary_trusted(dest_keyring, type, 132 payload, restrict_key); 133 } 134 #endif 135 136 /* 137 * Create the trusted keyrings 138 */ 139 static __init int system_trusted_keyring_init(void) 140 { 141 pr_notice("Initialise system trusted keyrings\n"); 142 143 builtin_trusted_keys = 144 keyring_alloc(".builtin_trusted_keys", 145 GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(), 146 ((KEY_POS_ALL & ~KEY_POS_SETATTR) | 147 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH), 148 KEY_ALLOC_NOT_IN_QUOTA, 149 NULL, NULL); 150 if (IS_ERR(builtin_trusted_keys)) 151 panic("Can't allocate builtin trusted keyring\n"); 152 153 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 154 secondary_trusted_keys = 155 keyring_alloc(".secondary_trusted_keys", 156 GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(), 157 ((KEY_POS_ALL & ~KEY_POS_SETATTR) | 158 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH | 159 KEY_USR_WRITE), 160 KEY_ALLOC_NOT_IN_QUOTA, 161 get_builtin_and_secondary_restriction(), 162 NULL); 163 if (IS_ERR(secondary_trusted_keys)) 164 panic("Can't allocate secondary trusted keyring\n"); 165 166 if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0) 167 panic("Can't link trusted keyrings\n"); 168 #endif 169 170 return 0; 171 } 172 173 /* 174 * Must be initialised before we try and load the keys into the keyring. 175 */ 176 device_initcall(system_trusted_keyring_init); 177 178 __init int load_module_cert(struct key *keyring) 179 { 180 if (!IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG)) 181 return 0; 182 183 pr_notice("Loading compiled-in module X.509 certificates\n"); 184 185 return x509_load_certificate_list(system_certificate_list, 186 module_cert_size, keyring); 187 } 188 189 /* 190 * Load the compiled-in list of X.509 certificates. 191 */ 192 static __init int load_system_certificate_list(void) 193 { 194 const u8 *p; 195 unsigned long size; 196 197 pr_notice("Loading compiled-in X.509 certificates\n"); 198 199 #ifdef CONFIG_MODULE_SIG 200 p = system_certificate_list; 201 size = system_certificate_list_size; 202 #else 203 p = system_certificate_list + module_cert_size; 204 size = system_certificate_list_size - module_cert_size; 205 #endif 206 207 return x509_load_certificate_list(p, size, builtin_trusted_keys); 208 } 209 late_initcall(load_system_certificate_list); 210 211 #ifdef CONFIG_SYSTEM_DATA_VERIFICATION 212 213 /** 214 * verify_pkcs7_message_sig - Verify a PKCS#7-based signature on system data. 215 * @data: The data to be verified (NULL if expecting internal data). 216 * @len: Size of @data. 217 * @pkcs7: The PKCS#7 message that is the signature. 218 * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, 219 * (void *)1UL for all trusted keys). 220 * @usage: The use to which the key is being put. 221 * @view_content: Callback to gain access to content. 222 * @ctx: Context for callback. 223 */ 224 int verify_pkcs7_message_sig(const void *data, size_t len, 225 struct pkcs7_message *pkcs7, 226 struct key *trusted_keys, 227 enum key_being_used_for usage, 228 int (*view_content)(void *ctx, 229 const void *data, size_t len, 230 size_t asn1hdrlen), 231 void *ctx) 232 { 233 int ret; 234 235 /* The data should be detached - so we need to supply it. */ 236 if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) { 237 pr_err("PKCS#7 signature with non-detached data\n"); 238 ret = -EBADMSG; 239 goto error; 240 } 241 242 ret = pkcs7_verify(pkcs7, usage); 243 if (ret < 0) 244 goto error; 245 246 if (!trusted_keys) { 247 trusted_keys = builtin_trusted_keys; 248 } else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) { 249 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 250 trusted_keys = secondary_trusted_keys; 251 #else 252 trusted_keys = builtin_trusted_keys; 253 #endif 254 } else if (trusted_keys == VERIFY_USE_PLATFORM_KEYRING) { 255 #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING 256 trusted_keys = platform_trusted_keys; 257 #else 258 trusted_keys = NULL; 259 #endif 260 if (!trusted_keys) { 261 ret = -ENOKEY; 262 pr_devel("PKCS#7 platform keyring is not available\n"); 263 goto error; 264 } 265 266 ret = is_key_on_revocation_list(pkcs7); 267 if (ret != -ENOKEY) { 268 pr_devel("PKCS#7 platform key is on revocation list\n"); 269 goto error; 270 } 271 } 272 ret = pkcs7_validate_trust(pkcs7, trusted_keys); 273 if (ret < 0) { 274 if (ret == -ENOKEY) 275 pr_devel("PKCS#7 signature not signed with a trusted key\n"); 276 goto error; 277 } 278 279 if (view_content) { 280 size_t asn1hdrlen; 281 282 ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen); 283 if (ret < 0) { 284 if (ret == -ENODATA) 285 pr_devel("PKCS#7 message does not contain data\n"); 286 goto error; 287 } 288 289 ret = view_content(ctx, data, len, asn1hdrlen); 290 } 291 292 error: 293 pr_devel("<==%s() = %d\n", __func__, ret); 294 return ret; 295 } 296 297 /** 298 * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. 299 * @data: The data to be verified (NULL if expecting internal data). 300 * @len: Size of @data. 301 * @raw_pkcs7: The PKCS#7 message that is the signature. 302 * @pkcs7_len: The size of @raw_pkcs7. 303 * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, 304 * (void *)1UL for all trusted keys). 305 * @usage: The use to which the key is being put. 306 * @view_content: Callback to gain access to content. 307 * @ctx: Context for callback. 308 */ 309 int verify_pkcs7_signature(const void *data, size_t len, 310 const void *raw_pkcs7, size_t pkcs7_len, 311 struct key *trusted_keys, 312 enum key_being_used_for usage, 313 int (*view_content)(void *ctx, 314 const void *data, size_t len, 315 size_t asn1hdrlen), 316 void *ctx) 317 { 318 struct pkcs7_message *pkcs7; 319 int ret; 320 321 pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); 322 if (IS_ERR(pkcs7)) 323 return PTR_ERR(pkcs7); 324 325 ret = verify_pkcs7_message_sig(data, len, pkcs7, trusted_keys, usage, 326 view_content, ctx); 327 328 pkcs7_free_message(pkcs7); 329 pr_devel("<==%s() = %d\n", __func__, ret); 330 return ret; 331 } 332 EXPORT_SYMBOL_GPL(verify_pkcs7_signature); 333 334 #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ 335 336 #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING 337 void __init set_platform_trusted_keys(struct key *keyring) 338 { 339 platform_trusted_keys = keyring; 340 } 341 #endif 342