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c26fd69f DH |
1 | /* Instantiate a public key crypto key from an X.509 Certificate |
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 | #define pr_fmt(fmt) "X.509: "fmt | |
13 | #include <linux/module.h> | |
14 | #include <linux/kernel.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/err.h> | |
17 | #include <linux/mpi.h> | |
18 | #include <linux/asn1_decoder.h> | |
19 | #include <keys/asymmetric-subtype.h> | |
20 | #include <keys/asymmetric-parser.h> | |
3be4beaf | 21 | #include <keys/system_keyring.h> |
c26fd69f DH |
22 | #include <crypto/hash.h> |
23 | #include "asymmetric_keys.h" | |
24 | #include "public_key.h" | |
25 | #include "x509_parser.h" | |
26 | ||
32c4741c | 27 | static bool use_builtin_keys; |
46963b77 | 28 | static struct asymmetric_key_id *ca_keyid; |
ffb70f61 DK |
29 | |
30 | #ifndef MODULE | |
31 | static int __init ca_keys_setup(char *str) | |
32 | { | |
33 | if (!str) /* default system keyring */ | |
34 | return 1; | |
35 | ||
46963b77 DH |
36 | if (strncmp(str, "id:", 3) == 0) { |
37 | struct asymmetric_key_id *p; | |
7a224e78 | 38 | p = asymmetric_key_hex_to_key_id(str + 3); |
46963b77 DH |
39 | if (p == ERR_PTR(-EINVAL)) |
40 | pr_err("Unparsable hex string in ca_keys\n"); | |
41 | else if (!IS_ERR(p)) | |
42 | ca_keyid = p; /* owner key 'id:xxxxxx' */ | |
43 | } else if (strcmp(str, "builtin") == 0) { | |
32c4741c | 44 | use_builtin_keys = true; |
46963b77 | 45 | } |
ffb70f61 DK |
46 | |
47 | return 1; | |
48 | } | |
49 | __setup("ca_keys=", ca_keys_setup); | |
50 | #endif | |
51 | ||
5ce43ad2 DH |
52 | /** |
53 | * x509_request_asymmetric_key - Request a key by X.509 certificate params. | |
54 | * @keyring: The keys to search. | |
46963b77 | 55 | * @kid: The key ID. |
f1b731db | 56 | * @partial: Use partial match if true, exact if false. |
5ce43ad2 DH |
57 | * |
58 | * Find a key in the given keyring by subject name and key ID. These might, | |
59 | * for instance, be the issuer name and the authority key ID of an X.509 | |
60 | * certificate that needs to be verified. | |
3be4beaf | 61 | */ |
5ce43ad2 | 62 | struct key *x509_request_asymmetric_key(struct key *keyring, |
f1b731db DK |
63 | const struct asymmetric_key_id *kid, |
64 | bool partial) | |
3be4beaf MZ |
65 | { |
66 | key_ref_t key; | |
46963b77 | 67 | char *id, *p; |
3be4beaf | 68 | |
46963b77 DH |
69 | /* Construct an identifier "id:<keyid>". */ |
70 | p = id = kmalloc(2 + 1 + kid->len * 2 + 1, GFP_KERNEL); | |
3be4beaf MZ |
71 | if (!id) |
72 | return ERR_PTR(-ENOMEM); | |
73 | ||
f1b731db DK |
74 | if (partial) { |
75 | *p++ = 'i'; | |
76 | *p++ = 'd'; | |
77 | } else { | |
78 | *p++ = 'e'; | |
79 | *p++ = 'x'; | |
80 | } | |
46963b77 DH |
81 | *p++ = ':'; |
82 | p = bin2hex(p, kid->data, kid->len); | |
83 | *p = 0; | |
3be4beaf MZ |
84 | |
85 | pr_debug("Look up: \"%s\"\n", id); | |
86 | ||
87 | key = keyring_search(make_key_ref(keyring, 1), | |
88 | &key_type_asymmetric, id); | |
89 | if (IS_ERR(key)) | |
5ce43ad2 | 90 | pr_debug("Request for key '%s' err %ld\n", id, PTR_ERR(key)); |
3be4beaf MZ |
91 | kfree(id); |
92 | ||
93 | if (IS_ERR(key)) { | |
94 | switch (PTR_ERR(key)) { | |
95 | /* Hide some search errors */ | |
96 | case -EACCES: | |
97 | case -ENOTDIR: | |
98 | case -EAGAIN: | |
99 | return ERR_PTR(-ENOKEY); | |
100 | default: | |
101 | return ERR_CAST(key); | |
102 | } | |
103 | } | |
104 | ||
105 | pr_devel("<==%s() = 0 [%x]\n", __func__, | |
106 | key_serial(key_ref_to_ptr(key))); | |
107 | return key_ref_to_ptr(key); | |
108 | } | |
cf5b50fd | 109 | EXPORT_SYMBOL_GPL(x509_request_asymmetric_key); |
3be4beaf | 110 | |
c26fd69f | 111 | /* |
b426beb6 DH |
112 | * Set up the signature parameters in an X.509 certificate. This involves |
113 | * digesting the signed data and extracting the signature. | |
c26fd69f | 114 | */ |
b426beb6 | 115 | int x509_get_sig_params(struct x509_certificate *cert) |
c26fd69f | 116 | { |
c26fd69f DH |
117 | struct crypto_shash *tfm; |
118 | struct shash_desc *desc; | |
119 | size_t digest_size, desc_size; | |
b426beb6 | 120 | void *digest; |
c26fd69f DH |
121 | int ret; |
122 | ||
123 | pr_devel("==>%s()\n", __func__); | |
b426beb6 | 124 | |
41559420 DH |
125 | if (cert->unsupported_crypto) |
126 | return -ENOPKG; | |
b426beb6 DH |
127 | if (cert->sig.rsa.s) |
128 | return 0; | |
129 | ||
130 | cert->sig.rsa.s = mpi_read_raw_data(cert->raw_sig, cert->raw_sig_size); | |
131 | if (!cert->sig.rsa.s) | |
132 | return -ENOMEM; | |
133 | cert->sig.nr_mpi = 1; | |
134 | ||
c26fd69f DH |
135 | /* Allocate the hashing algorithm we're going to need and find out how |
136 | * big the hash operational data will be. | |
137 | */ | |
3fe78ca2 | 138 | tfm = crypto_alloc_shash(hash_algo_name[cert->sig.pkey_hash_algo], 0, 0); |
41559420 DH |
139 | if (IS_ERR(tfm)) { |
140 | if (PTR_ERR(tfm) == -ENOENT) { | |
141 | cert->unsupported_crypto = true; | |
142 | return -ENOPKG; | |
143 | } | |
144 | return PTR_ERR(tfm); | |
145 | } | |
c26fd69f DH |
146 | |
147 | desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); | |
148 | digest_size = crypto_shash_digestsize(tfm); | |
149 | ||
b426beb6 DH |
150 | /* We allocate the hash operational data storage on the end of the |
151 | * digest storage space. | |
c26fd69f DH |
152 | */ |
153 | ret = -ENOMEM; | |
b426beb6 DH |
154 | digest = kzalloc(digest_size + desc_size, GFP_KERNEL); |
155 | if (!digest) | |
156 | goto error; | |
c26fd69f | 157 | |
b426beb6 DH |
158 | cert->sig.digest = digest; |
159 | cert->sig.digest_size = digest_size; | |
c26fd69f | 160 | |
b426beb6 DH |
161 | desc = digest + digest_size; |
162 | desc->tfm = tfm; | |
163 | desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; | |
c26fd69f DH |
164 | |
165 | ret = crypto_shash_init(desc); | |
166 | if (ret < 0) | |
167 | goto error; | |
b426beb6 DH |
168 | might_sleep(); |
169 | ret = crypto_shash_finup(desc, cert->tbs, cert->tbs_size, digest); | |
170 | error: | |
171 | crypto_free_shash(tfm); | |
172 | pr_devel("<==%s() = %d\n", __func__, ret); | |
173 | return ret; | |
174 | } | |
175 | EXPORT_SYMBOL_GPL(x509_get_sig_params); | |
c26fd69f | 176 | |
b426beb6 DH |
177 | /* |
178 | * Check the signature on a certificate using the provided public key | |
179 | */ | |
180 | int x509_check_signature(const struct public_key *pub, | |
181 | struct x509_certificate *cert) | |
182 | { | |
183 | int ret; | |
c26fd69f | 184 | |
b426beb6 | 185 | pr_devel("==>%s()\n", __func__); |
c26fd69f | 186 | |
b426beb6 DH |
187 | ret = x509_get_sig_params(cert); |
188 | if (ret < 0) | |
189 | return ret; | |
c26fd69f | 190 | |
b426beb6 | 191 | ret = public_key_verify_signature(pub, &cert->sig); |
41559420 DH |
192 | if (ret == -ENOPKG) |
193 | cert->unsupported_crypto = true; | |
c26fd69f | 194 | pr_debug("Cert Verification: %d\n", ret); |
c26fd69f DH |
195 | return ret; |
196 | } | |
b426beb6 | 197 | EXPORT_SYMBOL_GPL(x509_check_signature); |
c26fd69f | 198 | |
3be4beaf MZ |
199 | /* |
200 | * Check the new certificate against the ones in the trust keyring. If one of | |
201 | * those is the signing key and validates the new certificate, then mark the | |
202 | * new certificate as being trusted. | |
203 | * | |
204 | * Return 0 if the new certificate was successfully validated, 1 if we couldn't | |
205 | * find a matching parent certificate in the trusted list and an error if there | |
206 | * is a matching certificate but the signature check fails. | |
207 | */ | |
208 | static int x509_validate_trust(struct x509_certificate *cert, | |
209 | struct key *trust_keyring) | |
210 | { | |
3be4beaf MZ |
211 | struct key *key; |
212 | int ret = 1; | |
213 | ||
214 | if (!trust_keyring) | |
215 | return -EOPNOTSUPP; | |
216 | ||
f1b731db | 217 | if (ca_keyid && !asymmetric_key_id_partial(cert->authority, ca_keyid)) |
ffb70f61 DK |
218 | return -EPERM; |
219 | ||
f1b731db DK |
220 | key = x509_request_asymmetric_key(trust_keyring, cert->authority, |
221 | false); | |
3be4beaf | 222 | if (!IS_ERR(key)) { |
32c4741c DK |
223 | if (!use_builtin_keys |
224 | || test_bit(KEY_FLAG_BUILTIN, &key->flags)) | |
225 | ret = x509_check_signature(key->payload.data, cert); | |
3be4beaf MZ |
226 | key_put(key); |
227 | } | |
228 | return ret; | |
229 | } | |
230 | ||
c26fd69f DH |
231 | /* |
232 | * Attempt to parse a data blob for a key as an X509 certificate. | |
233 | */ | |
234 | static int x509_key_preparse(struct key_preparsed_payload *prep) | |
235 | { | |
46963b77 | 236 | struct asymmetric_key_ids *kids; |
c26fd69f | 237 | struct x509_certificate *cert; |
46963b77 | 238 | const char *q; |
c26fd69f | 239 | size_t srlen, sulen; |
46963b77 | 240 | char *desc = NULL, *p; |
c26fd69f DH |
241 | int ret; |
242 | ||
243 | cert = x509_cert_parse(prep->data, prep->datalen); | |
244 | if (IS_ERR(cert)) | |
245 | return PTR_ERR(cert); | |
246 | ||
247 | pr_devel("Cert Issuer: %s\n", cert->issuer); | |
248 | pr_devel("Cert Subject: %s\n", cert->subject); | |
2ecdb23b DH |
249 | |
250 | if (cert->pub->pkey_algo >= PKEY_ALGO__LAST || | |
251 | cert->sig.pkey_algo >= PKEY_ALGO__LAST || | |
252 | cert->sig.pkey_hash_algo >= PKEY_HASH__LAST || | |
253 | !pkey_algo[cert->pub->pkey_algo] || | |
254 | !pkey_algo[cert->sig.pkey_algo] || | |
3fe78ca2 | 255 | !hash_algo_name[cert->sig.pkey_hash_algo]) { |
2ecdb23b DH |
256 | ret = -ENOPKG; |
257 | goto error_free_cert; | |
258 | } | |
259 | ||
67f7d60b | 260 | pr_devel("Cert Key Algo: %s\n", pkey_algo_name[cert->pub->pkey_algo]); |
2f1c4fef | 261 | pr_devel("Cert Valid From: %04ld-%02d-%02d %02d:%02d:%02d\n", |
a5752d11 DH |
262 | cert->valid_from.tm_year + 1900, cert->valid_from.tm_mon + 1, |
263 | cert->valid_from.tm_mday, cert->valid_from.tm_hour, | |
264 | cert->valid_from.tm_min, cert->valid_from.tm_sec); | |
2f1c4fef | 265 | pr_devel("Cert Valid To: %04ld-%02d-%02d %02d:%02d:%02d\n", |
a5752d11 DH |
266 | cert->valid_to.tm_year + 1900, cert->valid_to.tm_mon + 1, |
267 | cert->valid_to.tm_mday, cert->valid_to.tm_hour, | |
268 | cert->valid_to.tm_min, cert->valid_to.tm_sec); | |
c7c8bb23 DK |
269 | pr_devel("Cert Signature: %s + %s\n", |
270 | pkey_algo_name[cert->sig.pkey_algo], | |
3fe78ca2 | 271 | hash_algo_name[cert->sig.pkey_hash_algo]); |
c26fd69f | 272 | |
67f7d60b | 273 | cert->pub->algo = pkey_algo[cert->pub->pkey_algo]; |
c26fd69f DH |
274 | cert->pub->id_type = PKEY_ID_X509; |
275 | ||
17334cab DH |
276 | /* Check the signature on the key if it appears to be self-signed */ |
277 | if (!cert->authority || | |
46963b77 | 278 | asymmetric_key_id_same(cert->skid, cert->authority)) { |
3be4beaf | 279 | ret = x509_check_signature(cert->pub, cert); /* self-signed */ |
c26fd69f DH |
280 | if (ret < 0) |
281 | goto error_free_cert; | |
3be4beaf MZ |
282 | } else if (!prep->trusted) { |
283 | ret = x509_validate_trust(cert, get_system_trusted_keyring()); | |
284 | if (!ret) | |
285 | prep->trusted = 1; | |
c26fd69f DH |
286 | } |
287 | ||
288 | /* Propose a description */ | |
289 | sulen = strlen(cert->subject); | |
dd2f6c44 DH |
290 | if (cert->raw_skid) { |
291 | srlen = cert->raw_skid_size; | |
292 | q = cert->raw_skid; | |
293 | } else { | |
294 | srlen = cert->raw_serial_size; | |
295 | q = cert->raw_serial; | |
296 | } | |
46963b77 DH |
297 | if (srlen > 1 && *q == 0) { |
298 | srlen--; | |
299 | q++; | |
300 | } | |
301 | ||
c26fd69f | 302 | ret = -ENOMEM; |
46963b77 | 303 | desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL); |
c26fd69f DH |
304 | if (!desc) |
305 | goto error_free_cert; | |
46963b77 DH |
306 | p = memcpy(desc, cert->subject, sulen); |
307 | p += sulen; | |
308 | *p++ = ':'; | |
309 | *p++ = ' '; | |
310 | p = bin2hex(p, q, srlen); | |
311 | *p = 0; | |
312 | ||
313 | kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL); | |
314 | if (!kids) | |
315 | goto error_free_desc; | |
316 | kids->id[0] = cert->id; | |
317 | kids->id[1] = cert->skid; | |
c26fd69f DH |
318 | |
319 | /* We're pinning the module by being linked against it */ | |
320 | __module_get(public_key_subtype.owner); | |
321 | prep->type_data[0] = &public_key_subtype; | |
46963b77 | 322 | prep->type_data[1] = kids; |
fc7c70e0 | 323 | prep->payload[0] = cert->pub; |
c26fd69f DH |
324 | prep->description = desc; |
325 | prep->quotalen = 100; | |
326 | ||
327 | /* We've finished with the certificate */ | |
328 | cert->pub = NULL; | |
46963b77 DH |
329 | cert->id = NULL; |
330 | cert->skid = NULL; | |
c26fd69f DH |
331 | desc = NULL; |
332 | ret = 0; | |
333 | ||
46963b77 DH |
334 | error_free_desc: |
335 | kfree(desc); | |
c26fd69f DH |
336 | error_free_cert: |
337 | x509_free_certificate(cert); | |
338 | return ret; | |
339 | } | |
340 | ||
341 | static struct asymmetric_key_parser x509_key_parser = { | |
342 | .owner = THIS_MODULE, | |
343 | .name = "x509", | |
344 | .parse = x509_key_preparse, | |
345 | }; | |
346 | ||
347 | /* | |
348 | * Module stuff | |
349 | */ | |
350 | static int __init x509_key_init(void) | |
351 | { | |
352 | return register_asymmetric_key_parser(&x509_key_parser); | |
353 | } | |
354 | ||
355 | static void __exit x509_key_exit(void) | |
356 | { | |
357 | unregister_asymmetric_key_parser(&x509_key_parser); | |
358 | } | |
359 | ||
360 | module_init(x509_key_init); | |
361 | module_exit(x509_key_exit); | |
e19aaa7d KK |
362 | |
363 | MODULE_DESCRIPTION("X.509 certificate parser"); | |
364 | MODULE_LICENSE("GPL"); |