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