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 &internal_key_acl, KEY_ALLOC_NOT_IN_QUOTA, 103 NULL, NULL); 104 if (IS_ERR(builtin_trusted_keys)) 105 panic("Can't allocate builtin trusted keyring\n"); 106 107 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING 108 secondary_trusted_keys = 109 keyring_alloc(".secondary_trusted_keys", 110 KUIDT_INIT(0), KGIDT_INIT(0), current_cred(), 111 &internal_writable_keyring_acl, KEY_ALLOC_NOT_IN_QUOTA, 112 get_builtin_and_secondary_restriction(), 113 NULL); 114 if (IS_ERR(secondary_trusted_keys)) 115 panic("Can't allocate secondary trusted keyring\n"); 116 117 if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0) 118 panic("Can't link trusted keyrings\n"); 119 #endif 120 121 return 0; 122 } 123 124 /* 125 * Must be initialised before we try and load the keys into the keyring. 126 */ 127 device_initcall(system_trusted_keyring_init); 128 129 /* 130 * Load the compiled-in list of X.509 certificates. 131 */ 132 static __init int load_system_certificate_list(void) 133 { 134 key_ref_t key; 135 const u8 *p, *end; 136 size_t plen; 137 138 pr_notice("Loading compiled-in X.509 certificates\n"); 139 140 p = system_certificate_list; 141 end = p + system_certificate_list_size; 142 while (p < end) { 143 /* Each cert begins with an ASN.1 SEQUENCE tag and must be more 144 * than 256 bytes in size. 145 */ 146 if (end - p < 4) 147 goto dodgy_cert; 148 if (p[0] != 0x30 && 149 p[1] != 0x82) 150 goto dodgy_cert; 151 plen = (p[2] << 8) | p[3]; 152 plen += 4; 153 if (plen > end - p) 154 goto dodgy_cert; 155 156 key = key_create_or_update(make_key_ref(builtin_trusted_keys, 1), 157 "asymmetric", 158 NULL, 159 p, 160 plen, 161 &internal_key_acl, 162 KEY_ALLOC_NOT_IN_QUOTA | 163 KEY_ALLOC_BUILT_IN | 164 KEY_ALLOC_BYPASS_RESTRICTION); 165 if (IS_ERR(key)) { 166 pr_err("Problem loading in-kernel X.509 certificate (%ld)\n", 167 PTR_ERR(key)); 168 } else { 169 pr_notice("Loaded X.509 cert '%s'\n", 170 key_ref_to_ptr(key)->description); 171 key_ref_put(key); 172 } 173 p += plen; 174 } 175 176 return 0; 177 178 dodgy_cert: 179 pr_err("Problem parsing in-kernel X.509 certificate list\n"); 180 return 0; 181 } 182 late_initcall(load_system_certificate_list); 183 184 #ifdef CONFIG_SYSTEM_DATA_VERIFICATION 185 186 /** 187 * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. 188 * @data: The data to be verified (NULL if expecting internal data). 189 * @len: Size of @data. 190 * @raw_pkcs7: The PKCS#7 message that is the signature. 191 * @pkcs7_len: The size of @raw_pkcs7. 192 * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, 193 * (void *)1UL for all trusted keys). 194 * @usage: The use to which the key is being put. 195 * @view_content: Callback to gain access to content. 196 * @ctx: Context for callback. 197 */ 198 int verify_pkcs7_signature(const void *data, size_t len, 199 const void *raw_pkcs7, size_t pkcs7_len, 200 struct key *trusted_keys, 201 enum key_being_used_for usage, 202 int (*view_content)(void *ctx, 203 const void *data, size_t len, 204 size_t asn1hdrlen), 205 void *ctx) 206 { 207 struct pkcs7_message *pkcs7; 208 int ret; 209 210 pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); 211 if (IS_ERR(pkcs7)) 212 return PTR_ERR(pkcs7); 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 pkcs7_free_message(pkcs7); 267 pr_devel("<==%s() = %d\n", __func__, ret); 268 return ret; 269 } 270 EXPORT_SYMBOL_GPL(verify_pkcs7_signature); 271 272 #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ 273 274 #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING 275 void __init set_platform_trusted_keys(struct key *keyring) 276 { 277 platform_trusted_keys = keyring; 278 } 279 #endif 280