blob: 8cde8ea8839374a3b5837c8db84a4f02867d202f
| 1 | /* System trusted keyring for trusted public keys |
| 2 | * |
| 3 | * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. |
| 4 | * Written by David Howells (dhowells@redhat.com) |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU General Public Licence |
| 8 | * as published by the Free Software Foundation; either version |
| 9 | * 2 of the Licence, or (at your option) any later version. |
| 10 | */ |
| 11 | |
| 12 | #include <linux/export.h> |
| 13 | #include <linux/kernel.h> |
| 14 | #include <linux/sched.h> |
| 15 | #include <linux/cred.h> |
| 16 | #include <linux/err.h> |
| 17 | #include <linux/verification.h> |
| 18 | #include <keys/asymmetric-type.h> |
| 19 | #include <keys/system_keyring.h> |
| 20 | #include <crypto/pkcs7.h> |
| 21 | |
| 22 | static struct key *builtin_trusted_keys; |
| 23 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING |
| 24 | static struct key *secondary_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 *keyring, |
| 37 | const struct key_type *type, |
| 38 | const union key_payload *payload) |
| 39 | { |
| 40 | return restrict_link_by_signature(builtin_trusted_keys, type, payload); |
| 41 | } |
| 42 | |
| 43 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING |
| 44 | /** |
| 45 | * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring |
| 46 | * addition by both builtin and secondary keyrings |
| 47 | * |
| 48 | * Restrict the addition of keys into a keyring based on the key-to-be-added |
| 49 | * being vouched for by a key in either the built-in or the secondary system |
| 50 | * keyrings. |
| 51 | */ |
| 52 | int restrict_link_by_builtin_and_secondary_trusted( |
| 53 | struct key *keyring, |
| 54 | const struct key_type *type, |
| 55 | const union key_payload *payload) |
| 56 | { |
| 57 | /* If we have a secondary trusted keyring, then that contains a link |
| 58 | * through to the builtin keyring and the search will follow that link. |
| 59 | */ |
| 60 | if (type == &key_type_keyring && |
| 61 | keyring == secondary_trusted_keys && |
| 62 | payload == &builtin_trusted_keys->payload) |
| 63 | /* Allow the builtin keyring to be added to the secondary */ |
| 64 | return 0; |
| 65 | |
| 66 | return restrict_link_by_signature(secondary_trusted_keys, type, payload); |
| 67 | } |
| 68 | #endif |
| 69 | |
| 70 | /* |
| 71 | * Create the trusted keyrings |
| 72 | */ |
| 73 | static __init int system_trusted_keyring_init(void) |
| 74 | { |
| 75 | pr_notice("Initialise system trusted keyrings\n"); |
| 76 | |
| 77 | builtin_trusted_keys = |
| 78 | keyring_alloc(".builtin_trusted_keys", |
| 79 | KUIDT_INIT(0), KGIDT_INIT(0), current_cred(), |
| 80 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | |
| 81 | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH), |
| 82 | KEY_ALLOC_NOT_IN_QUOTA, |
| 83 | NULL, NULL); |
| 84 | if (IS_ERR(builtin_trusted_keys)) |
| 85 | panic("Can't allocate builtin trusted keyring\n"); |
| 86 | |
| 87 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING |
| 88 | secondary_trusted_keys = |
| 89 | keyring_alloc(".secondary_trusted_keys", |
| 90 | KUIDT_INIT(0), KGIDT_INIT(0), current_cred(), |
| 91 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | |
| 92 | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH | |
| 93 | KEY_USR_WRITE), |
| 94 | KEY_ALLOC_NOT_IN_QUOTA, |
| 95 | restrict_link_by_builtin_and_secondary_trusted, |
| 96 | NULL); |
| 97 | if (IS_ERR(secondary_trusted_keys)) |
| 98 | panic("Can't allocate secondary trusted keyring\n"); |
| 99 | |
| 100 | if (key_link(secondary_trusted_keys, builtin_trusted_keys) < 0) |
| 101 | panic("Can't link trusted keyrings\n"); |
| 102 | #endif |
| 103 | |
| 104 | return 0; |
| 105 | } |
| 106 | |
| 107 | /* |
| 108 | * Must be initialised before we try and load the keys into the keyring. |
| 109 | */ |
| 110 | device_initcall(system_trusted_keyring_init); |
| 111 | |
| 112 | /* |
| 113 | * Load the compiled-in list of X.509 certificates. |
| 114 | */ |
| 115 | static __init int load_system_certificate_list(void) |
| 116 | { |
| 117 | key_ref_t key; |
| 118 | const u8 *p, *end; |
| 119 | size_t plen; |
| 120 | |
| 121 | pr_notice("Loading compiled-in X.509 certificates\n"); |
| 122 | |
| 123 | p = system_certificate_list; |
| 124 | end = p + system_certificate_list_size; |
| 125 | while (p < end) { |
| 126 | /* Each cert begins with an ASN.1 SEQUENCE tag and must be more |
| 127 | * than 256 bytes in size. |
| 128 | */ |
| 129 | if (end - p < 4) |
| 130 | goto dodgy_cert; |
| 131 | if (p[0] != 0x30 && |
| 132 | p[1] != 0x82) |
| 133 | goto dodgy_cert; |
| 134 | plen = (p[2] << 8) | p[3]; |
| 135 | plen += 4; |
| 136 | if (plen > end - p) |
| 137 | goto dodgy_cert; |
| 138 | |
| 139 | key = key_create_or_update(make_key_ref(builtin_trusted_keys, 1), |
| 140 | "asymmetric", |
| 141 | NULL, |
| 142 | p, |
| 143 | plen, |
| 144 | ((KEY_POS_ALL & ~KEY_POS_SETATTR) | |
| 145 | KEY_USR_VIEW | KEY_USR_READ), |
| 146 | KEY_ALLOC_NOT_IN_QUOTA | |
| 147 | KEY_ALLOC_BUILT_IN | |
| 148 | KEY_ALLOC_BYPASS_RESTRICTION); |
| 149 | if (IS_ERR(key)) { |
| 150 | pr_err("Problem loading in-kernel X.509 certificate (%ld)\n", |
| 151 | PTR_ERR(key)); |
| 152 | } else { |
| 153 | pr_notice("Loaded X.509 cert '%s'\n", |
| 154 | key_ref_to_ptr(key)->description); |
| 155 | key_ref_put(key); |
| 156 | } |
| 157 | p += plen; |
| 158 | } |
| 159 | |
| 160 | return 0; |
| 161 | |
| 162 | dodgy_cert: |
| 163 | pr_err("Problem parsing in-kernel X.509 certificate list\n"); |
| 164 | return 0; |
| 165 | } |
| 166 | late_initcall(load_system_certificate_list); |
| 167 | |
| 168 | #ifdef CONFIG_SYSTEM_DATA_VERIFICATION |
| 169 | |
| 170 | /** |
| 171 | * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. |
| 172 | * @data: The data to be verified (NULL if expecting internal data). |
| 173 | * @len: Size of @data. |
| 174 | * @raw_pkcs7: The PKCS#7 message that is the signature. |
| 175 | * @pkcs7_len: The size of @raw_pkcs7. |
| 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_signature(const void *data, size_t len, |
| 183 | const void *raw_pkcs7, size_t pkcs7_len, |
| 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 | struct pkcs7_message *pkcs7; |
| 192 | int ret; |
| 193 | |
| 194 | pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); |
| 195 | if (IS_ERR(pkcs7)) |
| 196 | return PTR_ERR(pkcs7); |
| 197 | |
| 198 | /* The data should be detached - so we need to supply it. */ |
| 199 | if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) { |
| 200 | pr_err("PKCS#7 signature with non-detached data\n"); |
| 201 | ret = -EBADMSG; |
| 202 | goto error; |
| 203 | } |
| 204 | |
| 205 | ret = pkcs7_verify(pkcs7, usage); |
| 206 | if (ret < 0) |
| 207 | goto error; |
| 208 | |
| 209 | if (!trusted_keys) { |
| 210 | trusted_keys = builtin_trusted_keys; |
| 211 | } else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) { |
| 212 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING |
| 213 | trusted_keys = secondary_trusted_keys; |
| 214 | #else |
| 215 | trusted_keys = builtin_trusted_keys; |
| 216 | #endif |
| 217 | } |
| 218 | ret = pkcs7_validate_trust(pkcs7, trusted_keys); |
| 219 | if (ret < 0) { |
| 220 | if (ret == -ENOKEY) |
| 221 | pr_err("PKCS#7 signature not signed with a trusted key\n"); |
| 222 | goto error; |
| 223 | } |
| 224 | |
| 225 | if (view_content) { |
| 226 | size_t asn1hdrlen; |
| 227 | |
| 228 | ret = pkcs7_get_content_data(pkcs7, &data, &len, &asn1hdrlen); |
| 229 | if (ret < 0) { |
| 230 | if (ret == -ENODATA) |
| 231 | pr_devel("PKCS#7 message does not contain data\n"); |
| 232 | goto error; |
| 233 | } |
| 234 | |
| 235 | ret = view_content(ctx, data, len, asn1hdrlen); |
| 236 | } |
| 237 | |
| 238 | error: |
| 239 | pkcs7_free_message(pkcs7); |
| 240 | pr_devel("<==%s() = %d\n", __func__, ret); |
| 241 | return ret; |
| 242 | } |
| 243 | EXPORT_SYMBOL_GPL(verify_pkcs7_signature); |
| 244 | #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ |
| 245 | |
| 246 | /** |
| 247 | * verify_signature_one - Verify a signature with keys from given keyring |
| 248 | * @sig: The signature to be verified |
| 249 | * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, |
| 250 | * (void *)1UL for all trusted keys). |
| 251 | * @keyid: key description (not partial) |
| 252 | */ |
| 253 | int verify_signature_one(const struct public_key_signature *sig, |
| 254 | struct key *trusted_keys, const char *keyid) |
| 255 | { |
| 256 | key_ref_t ref; |
| 257 | struct key *key; |
| 258 | int ret; |
| 259 | |
| 260 | if (!sig) |
| 261 | return -EBADMSG; |
| 262 | if (!trusted_keys) { |
| 263 | trusted_keys = builtin_trusted_keys; |
| 264 | } else if (trusted_keys == (void *)1UL) { |
| 265 | #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING |
| 266 | trusted_keys = secondary_trusted_keys; |
| 267 | #else |
| 268 | trusted_keys = builtin_trusted_keys; |
| 269 | #endif |
| 270 | } |
| 271 | |
| 272 | ref = keyring_search(make_key_ref(trusted_keys, 1), |
| 273 | &key_type_asymmetric, keyid); |
| 274 | if (IS_ERR(ref)) { |
| 275 | pr_err("Asymmetric key (%s) not found in keyring(%s)\n", |
| 276 | keyid, trusted_keys->description); |
| 277 | return -ENOKEY; |
| 278 | } |
| 279 | |
| 280 | key = key_ref_to_ptr(ref); |
| 281 | ret = verify_signature(key, sig); |
| 282 | key_put(key); |
| 283 | return ret; |
| 284 | } |
| 285 | EXPORT_SYMBOL_GPL(verify_signature_one); |
| 286 | |
| 287 |