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/verification.h> 15 #include <keys/asymmetric-type.h> 16 #include <keys/system_keyring.h> 17 #include <crypto/pkcs7.h> 18 19 static struct key *builtin_trusted_keys; 20 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 21 static struct key *secondary_trusted_keys; 22 #endif 23 #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING 24 static struct key *platform_trusted_keys; 25 #endif 26 27 extern __initconst const u8 system_certificate_list[]; 28 extern __initconst const unsigned long system_certificate_list_size; 29 30 /** 31 * restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA 32 * 33 * Restrict the addition of keys into a keyring based on the key-to-be-added 34 * being vouched for by a key in the built in system keyring. 35 */ 36 int restrict_link_by_builtin_trusted(struct key *dest_keyring, 37 const struct key_type *type, 38 const union key_payload *payload, 39 struct key *restriction_key) 40 { 41 return restrict_link_by_signature(dest_keyring, type, payload, 42 builtin_trusted_keys); 43 } 44 45 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 46 /** 47 * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring 48 * addition by both builtin and secondary keyrings 49 * 50 * Restrict the addition of keys into a keyring based on the key-to-be-added 51 * being vouched for by a key in either the built-in or the secondary system 52 * keyrings. 53 */ 54 int restrict_link_by_builtin_and_secondary_trusted( 55 struct key *dest_keyring, 56 const struct key_type *type, 57 const union key_payload *payload, 58 struct key *restrict_key) 59 { 60 /* If we have a secondary trusted keyring, then that contains a link 61 * through to the builtin keyring and the search will follow that link. 62 */ 63 if (type == &key_type_keyring && 64 dest_keyring == secondary_trusted_keys && 65 payload == &builtin_trusted_keys->payload) 66 /* Allow the builtin keyring to be added to the secondary */ 67 return 0; 68 69 return restrict_link_by_signature(dest_keyring, type, payload, 70 secondary_trusted_keys); 71 } 72 73 /** 74 * Allocate a struct key_restriction for the "builtin and secondary trust" 75 * keyring. Only for use in system_trusted_keyring_init(). 76 */ 77 static __init struct key_restriction *get_builtin_and_secondary_restriction(void) 78 { 79 struct key_restriction *restriction; 80 81 restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL); 82 83 if (!restriction) 84 panic("Can't allocate secondary trusted keyring restriction\n"); 85 86 restriction->check = restrict_link_by_builtin_and_secondary_trusted; 87 88 return restriction; 89 } 90 #endif 91 92 /* 93 * Create the trusted keyrings 94 */ 95 static __init int system_trusted_keyring_init(void) 96 { 97 pr_notice("Initialise system trusted keyrings\n"); 98 99 builtin_trusted_keys = 100 keyring_alloc(".builtin_trusted_keys", 101 KUIDT_INIT(0), KGIDT_INIT(0), current_cred(), 102 ((KEY_POS_ALL & ~KEY_POS_SETATTR) | 103 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH), 104 KEY_ALLOC_NOT_IN_QUOTA, 105 NULL, NULL); 106 if (IS_ERR(builtin_trusted_keys)) 107 panic("Can't allocate builtin trusted keyring\n"); 108 109 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 110 secondary_trusted_keys = 111 keyring_alloc(".secondary_trusted_keys", 112 KUIDT_INIT(0), KGIDT_INIT(0), current_cred(), 113 ((KEY_POS_ALL & ~KEY_POS_SETATTR) | 114 KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH | 115 KEY_USR_WRITE), 116 KEY_ALLOC_NOT_IN_QUOTA, 117 get_builtin_and_secondary_restriction(), 118 NULL); 119 if (IS_ERR(secondary_trusted_keys)) 120 panic("Can't allocate secondary trusted keyring\n"); 121 122 if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0) 123 panic("Can't link trusted keyrings\n"); 124 #endif 125 126 return 0; 127 } 128 129 /* 130 * Must be initialised before we try and load the keys into the keyring. 131 */ 132 device_initcall(system_trusted_keyring_init); 133 134 /* 135 * Load the compiled-in list of X.509 certificates. 136 */ 137 static __init int load_system_certificate_list(void) 138 { 139 key_ref_t key; 140 const u8 *p, *end; 141 size_t plen; 142 143 pr_notice("Loading compiled-in X.509 certificates\n"); 144 145 p = system_certificate_list; 146 end = p + system_certificate_list_size; 147 while (p < end) { 148 /* Each cert begins with an ASN.1 SEQUENCE tag and must be more 149 * than 256 bytes in size. 150 */ 151 if (end - p < 4) 152 goto dodgy_cert; 153 if (p[0] != 0x30 && 154 p[1] != 0x82) 155 goto dodgy_cert; 156 plen = (p[2] << 8) | p[3]; 157 plen += 4; 158 if (plen > end - p) 159 goto dodgy_cert; 160 161 key = key_create_or_update(make_key_ref(builtin_trusted_keys, 1), 162 "asymmetric", 163 NULL, 164 p, 165 plen, 166 ((KEY_POS_ALL & ~KEY_POS_SETATTR) | 167 KEY_USR_VIEW | KEY_USR_READ), 168 KEY_ALLOC_NOT_IN_QUOTA | 169 KEY_ALLOC_BUILT_IN | 170 KEY_ALLOC_BYPASS_RESTRICTION); 171 if (IS_ERR(key)) { 172 pr_err("Problem loading in-kernel X.509 certificate (%ld)\n", 173 PTR_ERR(key)); 174 } else { 175 pr_notice("Loaded X.509 cert '%s'\n", 176 key_ref_to_ptr(key)->description); 177 key_ref_put(key); 178 } 179 p += plen; 180 } 181 182 return 0; 183 184 dodgy_cert: 185 pr_err("Problem parsing in-kernel X.509 certificate list\n"); 186 return 0; 187 } 188 late_initcall(load_system_certificate_list); 189 190 #ifdef CONFIG_SYSTEM_DATA_VERIFICATION 191 192 /** 193 * verify_pkcs7_message_sig - Verify a PKCS#7-based signature on system data. 194 * @data: The data to be verified (NULL if expecting internal data). 195 * @len: Size of @data. 196 * @pkcs7: The PKCS#7 message that is the signature. 197 * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, 198 * (void *)1UL for all trusted keys). 199 * @usage: The use to which the key is being put. 200 * @view_content: Callback to gain access to content. 201 * @ctx: Context for callback. 202 */ 203 int verify_pkcs7_message_sig(const void *data, size_t len, 204 struct pkcs7_message *pkcs7, 205 struct key *trusted_keys, 206 enum key_being_used_for usage, 207 int (*view_content)(void *ctx, 208 const void *data, size_t len, 209 size_t asn1hdrlen), 210 void *ctx) 211 { 212 int ret; 213 214 /* The data should be detached - so we need to supply it. */ 215 if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) { 216 pr_err("PKCS#7 signature with non-detached data\n"); 217 ret = -EBADMSG; 218 goto error; 219 } 220 221 ret = pkcs7_verify(pkcs7, usage); 222 if (ret < 0) 223 goto error; 224 225 if (!trusted_keys) { 226 trusted_keys = builtin_trusted_keys; 227 } else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) { 228 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 229 trusted_keys = secondary_trusted_keys; 230 #else 231 trusted_keys = builtin_trusted_keys; 232 #endif 233 } else if (trusted_keys == VERIFY_USE_PLATFORM_KEYRING) { 234 #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING 235 trusted_keys = platform_trusted_keys; 236 #else 237 trusted_keys = NULL; 238 #endif 239 if (!trusted_keys) { 240 ret = -ENOKEY; 241 pr_devel("PKCS#7 platform keyring is not available\n"); 242 goto error; 243 } 244 } 245 ret = pkcs7_validate_trust(pkcs7, trusted_keys); 246 if (ret < 0) { 247 if (ret == -ENOKEY) 248 pr_devel("PKCS#7 signature not signed with a trusted key\n"); 249 goto error; 250 } 251 252 if (view_content) { 253 size_t asn1hdrlen; 254 255 ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen); 256 if (ret < 0) { 257 if (ret == -ENODATA) 258 pr_devel("PKCS#7 message does not contain data\n"); 259 goto error; 260 } 261 262 ret = view_content(ctx, data, len, asn1hdrlen); 263 } 264 265 error: 266 pr_devel("<==%s() = %d\n", __func__, ret); 267 return ret; 268 } 269 270 /** 271 * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. 272 * @data: The data to be verified (NULL if expecting internal data). 273 * @len: Size of @data. 274 * @raw_pkcs7: The PKCS#7 message that is the signature. 275 * @pkcs7_len: The size of @raw_pkcs7. 276 * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, 277 * (void *)1UL for all trusted keys). 278 * @usage: The use to which the key is being put. 279 * @view_content: Callback to gain access to content. 280 * @ctx: Context for callback. 281 */ 282 int verify_pkcs7_signature(const void *data, size_t len, 283 const void *raw_pkcs7, size_t pkcs7_len, 284 struct key *trusted_keys, 285 enum key_being_used_for usage, 286 int (*view_content)(void *ctx, 287 const void *data, size_t len, 288 size_t asn1hdrlen), 289 void *ctx) 290 { 291 struct pkcs7_message *pkcs7; 292 int ret; 293 294 pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); 295 if (IS_ERR(pkcs7)) 296 return PTR_ERR(pkcs7); 297 298 ret = verify_pkcs7_message_sig(data, len, pkcs7, trusted_keys, usage, 299 view_content, ctx); 300 301 pkcs7_free_message(pkcs7); 302 pr_devel("<==%s() = %d\n", __func__, ret); 303 return ret; 304 } 305 EXPORT_SYMBOL_GPL(verify_pkcs7_signature); 306 307 #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ 308 309 #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING 310 void __init set_platform_trusted_keys(struct key *keyring) 311 { 312 platform_trusted_keys = keyring; 313 } 314 #endif 315