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_PLATFORM_KEYRING 26 static struct key *platform_trusted_keys; 27 #endif 28 29 extern __initconst const u8 system_certificate_list[]; 30 extern __initconst const unsigned long system_certificate_list_size; 31 extern __initconst const unsigned long module_cert_size; 32 33 /** 34 * restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA 35 * 36 * Restrict the addition of keys into a keyring based on the key-to-be-added 37 * being vouched for by a key in the built in system keyring. 38 */ 39 int restrict_link_by_builtin_trusted(struct key *dest_keyring, 40 const struct key_type *type, 41 const union key_payload *payload, 42 struct key *restriction_key) 43 { 44 return restrict_link_by_signature(dest_keyring, type, payload, 45 builtin_trusted_keys); 46 } 47 48 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 49 /** 50 * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring 51 * addition by both builtin and secondary keyrings 52 * 53 * Restrict the addition of keys into a keyring based on the key-to-be-added 54 * being vouched for by a key in either the built-in or the secondary system 55 * keyrings. 56 */ 57 int restrict_link_by_builtin_and_secondary_trusted( 58 struct key *dest_keyring, 59 const struct key_type *type, 60 const union key_payload *payload, 61 struct key *restrict_key) 62 { 63 /* If we have a secondary trusted keyring, then that contains a link 64 * through to the builtin keyring and the search will follow that link. 65 */ 66 if (type == &key_type_keyring && 67 dest_keyring == secondary_trusted_keys && 68 payload == &builtin_trusted_keys->payload) 69 /* Allow the builtin keyring to be added to the secondary */ 70 return 0; 71 72 return restrict_link_by_signature(dest_keyring, type, payload, 73 secondary_trusted_keys); 74 } 75 76 /** 77 * Allocate a struct key_restriction for the "builtin and secondary trust" 78 * keyring. Only for use in system_trusted_keyring_init(). 79 */ 80 static __init struct key_restriction *get_builtin_and_secondary_restriction(void) 81 { 82 struct key_restriction *restriction; 83 84 restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL); 85 86 if (!restriction) 87 panic("Can't allocate secondary trusted keyring restriction\n"); 88 89 restriction->check = restrict_link_by_builtin_and_secondary_trusted; 90 91 return restriction; 92 } 93 #endif 94 95 /* 96 * Create the trusted keyrings 97 */ 98 static __init int system_trusted_keyring_init(void) 99 { 100 pr_notice("Initialise system trusted keyrings\n"); 101 102 builtin_trusted_keys = 103 keyring_alloc(".builtin_trusted_keys", 104 GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(), 105 ((KEY_POS_ALL & ~KEY_POS_SETATTR) | 106 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH), 107 KEY_ALLOC_NOT_IN_QUOTA, 108 NULL, NULL); 109 if (IS_ERR(builtin_trusted_keys)) 110 panic("Can't allocate builtin trusted keyring\n"); 111 112 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 113 secondary_trusted_keys = 114 keyring_alloc(".secondary_trusted_keys", 115 GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(), 116 ((KEY_POS_ALL & ~KEY_POS_SETATTR) | 117 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH | 118 KEY_USR_WRITE), 119 KEY_ALLOC_NOT_IN_QUOTA, 120 get_builtin_and_secondary_restriction(), 121 NULL); 122 if (IS_ERR(secondary_trusted_keys)) 123 panic("Can't allocate secondary trusted keyring\n"); 124 125 if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0) 126 panic("Can't link trusted keyrings\n"); 127 #endif 128 129 return 0; 130 } 131 132 /* 133 * Must be initialised before we try and load the keys into the keyring. 134 */ 135 device_initcall(system_trusted_keyring_init); 136 137 __init int load_module_cert(struct key *keyring) 138 { 139 if (!IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG)) 140 return 0; 141 142 pr_notice("Loading compiled-in module X.509 certificates\n"); 143 144 return load_certificate_list(system_certificate_list, module_cert_size, keyring); 145 } 146 147 /* 148 * Load the compiled-in list of X.509 certificates. 149 */ 150 static __init int load_system_certificate_list(void) 151 { 152 const u8 *p; 153 unsigned long size; 154 155 pr_notice("Loading compiled-in X.509 certificates\n"); 156 157 #ifdef CONFIG_MODULE_SIG 158 p = system_certificate_list; 159 size = system_certificate_list_size; 160 #else 161 p = system_certificate_list + module_cert_size; 162 size = system_certificate_list_size - module_cert_size; 163 #endif 164 165 return load_certificate_list(p, size, builtin_trusted_keys); 166 } 167 late_initcall(load_system_certificate_list); 168 169 #ifdef CONFIG_SYSTEM_DATA_VERIFICATION 170 171 /** 172 * verify_pkcs7_message_sig - Verify a PKCS#7-based signature on system data. 173 * @data: The data to be verified (NULL if expecting internal data). 174 * @len: Size of @data. 175 * @pkcs7: The PKCS#7 message that is the signature. 176 * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, 177 * (void *)1UL for all trusted keys). 178 * @usage: The use to which the key is being put. 179 * @view_content: Callback to gain access to content. 180 * @ctx: Context for callback. 181 */ 182 int verify_pkcs7_message_sig(const void *data, size_t len, 183 struct pkcs7_message *pkcs7, 184 struct key *trusted_keys, 185 enum key_being_used_for usage, 186 int (*view_content)(void *ctx, 187 const void *data, size_t len, 188 size_t asn1hdrlen), 189 void *ctx) 190 { 191 int ret; 192 193 /* The data should be detached - so we need to supply it. */ 194 if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) { 195 pr_err("PKCS#7 signature with non-detached data\n"); 196 ret = -EBADMSG; 197 goto error; 198 } 199 200 ret = pkcs7_verify(pkcs7, usage); 201 if (ret < 0) 202 goto error; 203 204 if (!trusted_keys) { 205 trusted_keys = builtin_trusted_keys; 206 } else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) { 207 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 208 trusted_keys = secondary_trusted_keys; 209 #else 210 trusted_keys = builtin_trusted_keys; 211 #endif 212 } else if (trusted_keys == VERIFY_USE_PLATFORM_KEYRING) { 213 #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING 214 trusted_keys = platform_trusted_keys; 215 #else 216 trusted_keys = NULL; 217 #endif 218 if (!trusted_keys) { 219 ret = -ENOKEY; 220 pr_devel("PKCS#7 platform keyring is not available\n"); 221 goto error; 222 } 223 224 ret = is_key_on_revocation_list(pkcs7); 225 if (ret != -ENOKEY) { 226 pr_devel("PKCS#7 platform key is on revocation list\n"); 227 goto error; 228 } 229 } 230 ret = pkcs7_validate_trust(pkcs7, trusted_keys); 231 if (ret < 0) { 232 if (ret == -ENOKEY) 233 pr_devel("PKCS#7 signature not signed with a trusted key\n"); 234 goto error; 235 } 236 237 if (view_content) { 238 size_t asn1hdrlen; 239 240 ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen); 241 if (ret < 0) { 242 if (ret == -ENODATA) 243 pr_devel("PKCS#7 message does not contain data\n"); 244 goto error; 245 } 246 247 ret = view_content(ctx, data, len, asn1hdrlen); 248 } 249 250 error: 251 pr_devel("<==%s() = %d\n", __func__, ret); 252 return ret; 253 } 254 255 /** 256 * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. 257 * @data: The data to be verified (NULL if expecting internal data). 258 * @len: Size of @data. 259 * @raw_pkcs7: The PKCS#7 message that is the signature. 260 * @pkcs7_len: The size of @raw_pkcs7. 261 * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, 262 * (void *)1UL for all trusted keys). 263 * @usage: The use to which the key is being put. 264 * @view_content: Callback to gain access to content. 265 * @ctx: Context for callback. 266 */ 267 int verify_pkcs7_signature(const void *data, size_t len, 268 const void *raw_pkcs7, size_t pkcs7_len, 269 struct key *trusted_keys, 270 enum key_being_used_for usage, 271 int (*view_content)(void *ctx, 272 const void *data, size_t len, 273 size_t asn1hdrlen), 274 void *ctx) 275 { 276 struct pkcs7_message *pkcs7; 277 int ret; 278 279 pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); 280 if (IS_ERR(pkcs7)) 281 return PTR_ERR(pkcs7); 282 283 ret = verify_pkcs7_message_sig(data, len, pkcs7, trusted_keys, usage, 284 view_content, ctx); 285 286 pkcs7_free_message(pkcs7); 287 pr_devel("<==%s() = %d\n", __func__, ret); 288 return ret; 289 } 290 EXPORT_SYMBOL_GPL(verify_pkcs7_signature); 291 292 #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ 293 294 #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING 295 void __init set_platform_trusted_keys(struct key *keyring) 296 { 297 platform_trusted_keys = keyring; 298 } 299 #endif 300