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 #include "common.h" 20 21 static struct key *builtin_trusted_keys; 22 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 23 static struct key *secondary_trusted_keys; 24 #endif 25 #ifdef CONFIG_INTEGRITY_MACHINE_KEYRING 26 static struct key *machine_trusted_keys; 27 #endif 28 #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING 29 static struct key *platform_trusted_keys; 30 #endif 31 32 extern __initconst const u8 system_certificate_list[]; 33 extern __initconst const unsigned long system_certificate_list_size; 34 extern __initconst const unsigned long module_cert_size; 35 36 /** 37 * restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA 38 * 39 * Restrict the addition of keys into a keyring based on the key-to-be-added 40 * being vouched for by a key in the built in system keyring. 41 */ 42 int restrict_link_by_builtin_trusted(struct key *dest_keyring, 43 const struct key_type *type, 44 const union key_payload *payload, 45 struct key *restriction_key) 46 { 47 return restrict_link_by_signature(dest_keyring, type, payload, 48 builtin_trusted_keys); 49 } 50 51 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 52 /** 53 * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring 54 * addition by both builtin and secondary keyrings 55 * 56 * Restrict the addition of keys into a keyring based on the key-to-be-added 57 * being vouched for by a key in either the built-in or the secondary system 58 * keyrings. 59 */ 60 int restrict_link_by_builtin_and_secondary_trusted( 61 struct key *dest_keyring, 62 const struct key_type *type, 63 const union key_payload *payload, 64 struct key *restrict_key) 65 { 66 /* If we have a secondary trusted keyring, then that contains a link 67 * through to the builtin keyring and the search will follow that link. 68 */ 69 if (type == &key_type_keyring && 70 dest_keyring == secondary_trusted_keys && 71 payload == &builtin_trusted_keys->payload) 72 /* Allow the builtin keyring to be added to the secondary */ 73 return 0; 74 75 return restrict_link_by_signature(dest_keyring, type, payload, 76 secondary_trusted_keys); 77 } 78 79 /** 80 * Allocate a struct key_restriction for the "builtin and secondary trust" 81 * keyring. Only for use in system_trusted_keyring_init(). 82 */ 83 static __init struct key_restriction *get_builtin_and_secondary_restriction(void) 84 { 85 struct key_restriction *restriction; 86 87 restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL); 88 89 if (!restriction) 90 panic("Can't allocate secondary trusted keyring restriction\n"); 91 92 if (IS_ENABLED(CONFIG_INTEGRITY_MACHINE_KEYRING)) 93 restriction->check = restrict_link_by_builtin_secondary_and_machine; 94 else 95 restriction->check = restrict_link_by_builtin_and_secondary_trusted; 96 97 return restriction; 98 } 99 #endif 100 #ifdef CONFIG_INTEGRITY_MACHINE_KEYRING 101 void __init set_machine_trusted_keys(struct key *keyring) 102 { 103 machine_trusted_keys = keyring; 104 105 if (key_link(secondary_trusted_keys, machine_trusted_keys) < 0) 106 panic("Can't link (machine) trusted keyrings\n"); 107 } 108 109 /** 110 * restrict_link_by_builtin_secondary_and_machine - Restrict keyring addition. 111 * @dest_keyring: Keyring being linked to. 112 * @type: The type of key being added. 113 * @payload: The payload of the new key. 114 * @restrict_key: A ring of keys that can be used to vouch for the new cert. 115 * 116 * Restrict the addition of keys into a keyring based on the key-to-be-added 117 * being vouched for by a key in either the built-in, the secondary, or 118 * the machine keyrings. 119 */ 120 int restrict_link_by_builtin_secondary_and_machine( 121 struct key *dest_keyring, 122 const struct key_type *type, 123 const union key_payload *payload, 124 struct key *restrict_key) 125 { 126 if (machine_trusted_keys && type == &key_type_keyring && 127 dest_keyring == secondary_trusted_keys && 128 payload == &machine_trusted_keys->payload) 129 /* Allow the machine keyring to be added to the secondary */ 130 return 0; 131 132 return restrict_link_by_builtin_and_secondary_trusted(dest_keyring, type, 133 payload, restrict_key); 134 } 135 #endif 136 137 /* 138 * Create the trusted keyrings 139 */ 140 static __init int system_trusted_keyring_init(void) 141 { 142 pr_notice("Initialise system trusted keyrings\n"); 143 144 builtin_trusted_keys = 145 keyring_alloc(".builtin_trusted_keys", 146 GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(), 147 ((KEY_POS_ALL & ~KEY_POS_SETATTR) | 148 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH), 149 KEY_ALLOC_NOT_IN_QUOTA, 150 NULL, NULL); 151 if (IS_ERR(builtin_trusted_keys)) 152 panic("Can't allocate builtin trusted keyring\n"); 153 154 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 155 secondary_trusted_keys = 156 keyring_alloc(".secondary_trusted_keys", 157 GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(), 158 ((KEY_POS_ALL & ~KEY_POS_SETATTR) | 159 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH | 160 KEY_USR_WRITE), 161 KEY_ALLOC_NOT_IN_QUOTA, 162 get_builtin_and_secondary_restriction(), 163 NULL); 164 if (IS_ERR(secondary_trusted_keys)) 165 panic("Can't allocate secondary trusted keyring\n"); 166 167 if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0) 168 panic("Can't link trusted keyrings\n"); 169 #endif 170 171 return 0; 172 } 173 174 /* 175 * Must be initialised before we try and load the keys into the keyring. 176 */ 177 device_initcall(system_trusted_keyring_init); 178 179 __init int load_module_cert(struct key *keyring) 180 { 181 if (!IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG)) 182 return 0; 183 184 pr_notice("Loading compiled-in module X.509 certificates\n"); 185 186 return load_certificate_list(system_certificate_list, 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 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