blob: 733c046aacc6e18e5e3b0b56ae97e0fa010fe7db [file] [log] [blame]
David Howellsc26fd692012-09-24 17:11:48 +01001/* 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>
David Howellsc26fd692012-09-24 17:11:48 +010016#include <keys/asymmetric-subtype.h>
17#include <keys/asymmetric-parser.h>
Mimi Zohar3be4bea2013-08-20 14:36:27 -040018#include <keys/system_keyring.h>
David Howellsc26fd692012-09-24 17:11:48 +010019#include <crypto/hash.h>
20#include "asymmetric_keys.h"
David Howellsc26fd692012-09-24 17:11:48 +010021#include "x509_parser.h"
22
Dmitry Kasatkin32c47412014-06-17 11:56:59 +030023static bool use_builtin_keys;
David Howells46963b72014-09-16 17:36:13 +010024static struct asymmetric_key_id *ca_keyid;
Dmitry Kasatkinffb70f62014-06-17 11:56:58 +030025
26#ifndef MODULE
Mimi Zoharf2b3dee2015-02-11 07:33:34 -050027static struct {
28 struct asymmetric_key_id id;
29 unsigned char data[10];
30} cakey;
31
Dmitry Kasatkinffb70f62014-06-17 11:56:58 +030032static int __init ca_keys_setup(char *str)
33{
34 if (!str) /* default system keyring */
35 return 1;
36
David Howells46963b72014-09-16 17:36:13 +010037 if (strncmp(str, "id:", 3) == 0) {
Mimi Zoharf2b3dee2015-02-11 07:33:34 -050038 struct asymmetric_key_id *p = &cakey.id;
39 size_t hexlen = (strlen(str) - 3) / 2;
40 int ret;
41
42 if (hexlen == 0 || hexlen > sizeof(cakey.data)) {
43 pr_err("Missing or invalid ca_keys id\n");
44 return 1;
45 }
46
47 ret = __asymmetric_key_hex_to_key_id(str + 3, p, hexlen);
48 if (ret < 0)
49 pr_err("Unparsable ca_keys id hex string\n");
50 else
David Howells46963b72014-09-16 17:36:13 +010051 ca_keyid = p; /* owner key 'id:xxxxxx' */
52 } else if (strcmp(str, "builtin") == 0) {
Dmitry Kasatkin32c47412014-06-17 11:56:59 +030053 use_builtin_keys = true;
David Howells46963b72014-09-16 17:36:13 +010054 }
Dmitry Kasatkinffb70f62014-06-17 11:56:58 +030055
56 return 1;
57}
58__setup("ca_keys=", ca_keys_setup);
59#endif
60
David Howells5ce43ad2014-07-28 14:11:32 +010061/**
62 * x509_request_asymmetric_key - Request a key by X.509 certificate params.
63 * @keyring: The keys to search.
David Howells4573b642015-07-20 21:16:26 +010064 * @id: The issuer & serialNumber to look for or NULL.
65 * @skid: The subjectKeyIdentifier to look for or NULL.
Dmitry Kasatkinf1b731d2014-10-06 15:21:05 +010066 * @partial: Use partial match if true, exact if false.
David Howells5ce43ad2014-07-28 14:11:32 +010067 *
David Howells4573b642015-07-20 21:16:26 +010068 * Find a key in the given keyring by identifier. The preferred identifier is
69 * the issuer + serialNumber and the fallback identifier is the
70 * subjectKeyIdentifier. If both are given, the lookup is by the former, but
71 * the latter must also match.
Mimi Zohar3be4bea2013-08-20 14:36:27 -040072 */
David Howells5ce43ad2014-07-28 14:11:32 +010073struct key *x509_request_asymmetric_key(struct key *keyring,
David Howells4573b642015-07-20 21:16:26 +010074 const struct asymmetric_key_id *id,
75 const struct asymmetric_key_id *skid,
Dmitry Kasatkinf1b731d2014-10-06 15:21:05 +010076 bool partial)
Mimi Zohar3be4bea2013-08-20 14:36:27 -040077{
David Howells4573b642015-07-20 21:16:26 +010078 struct key *key;
79 key_ref_t ref;
80 const char *lookup;
81 char *req, *p;
82 int len;
Mimi Zohar3be4bea2013-08-20 14:36:27 -040083
David Howells4573b642015-07-20 21:16:26 +010084 if (id) {
85 lookup = id->data;
86 len = id->len;
87 } else {
88 lookup = skid->data;
89 len = skid->len;
90 }
91
David Howells46963b72014-09-16 17:36:13 +010092 /* Construct an identifier "id:<keyid>". */
David Howells4573b642015-07-20 21:16:26 +010093 p = req = kmalloc(2 + 1 + len * 2 + 1, GFP_KERNEL);
94 if (!req)
Mimi Zohar3be4bea2013-08-20 14:36:27 -040095 return ERR_PTR(-ENOMEM);
96
Dmitry Kasatkinf1b731d2014-10-06 15:21:05 +010097 if (partial) {
98 *p++ = 'i';
99 *p++ = 'd';
100 } else {
101 *p++ = 'e';
102 *p++ = 'x';
103 }
David Howells46963b72014-09-16 17:36:13 +0100104 *p++ = ':';
David Howells4573b642015-07-20 21:16:26 +0100105 p = bin2hex(p, lookup, len);
David Howells46963b72014-09-16 17:36:13 +0100106 *p = 0;
Mimi Zohar3be4bea2013-08-20 14:36:27 -0400107
David Howells4573b642015-07-20 21:16:26 +0100108 pr_debug("Look up: \"%s\"\n", req);
Mimi Zohar3be4bea2013-08-20 14:36:27 -0400109
David Howells4573b642015-07-20 21:16:26 +0100110 ref = keyring_search(make_key_ref(keyring, 1),
111 &key_type_asymmetric, req);
112 if (IS_ERR(ref))
113 pr_debug("Request for key '%s' err %ld\n", req, PTR_ERR(ref));
114 kfree(req);
Mimi Zohar3be4bea2013-08-20 14:36:27 -0400115
David Howells4573b642015-07-20 21:16:26 +0100116 if (IS_ERR(ref)) {
117 switch (PTR_ERR(ref)) {
Mimi Zohar3be4bea2013-08-20 14:36:27 -0400118 /* Hide some search errors */
119 case -EACCES:
120 case -ENOTDIR:
121 case -EAGAIN:
122 return ERR_PTR(-ENOKEY);
123 default:
David Howells4573b642015-07-20 21:16:26 +0100124 return ERR_CAST(ref);
Mimi Zohar3be4bea2013-08-20 14:36:27 -0400125 }
126 }
127
David Howells4573b642015-07-20 21:16:26 +0100128 key = key_ref_to_ptr(ref);
129 if (id && skid) {
130 const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
131 if (!kids->id[1]) {
132 pr_debug("issuer+serial match, but expected SKID missing\n");
133 goto reject;
134 }
135 if (!asymmetric_key_id_same(skid, kids->id[1])) {
136 pr_debug("issuer+serial match, but SKID does not\n");
137 goto reject;
138 }
139 }
140
141 pr_devel("<==%s() = 0 [%x]\n", __func__, key_serial(key));
142 return key;
143
144reject:
145 key_put(key);
146 return ERR_PTR(-EKEYREJECTED);
Mimi Zohar3be4bea2013-08-20 14:36:27 -0400147}
David Howellscf5b50f2014-08-03 12:54:48 +0100148EXPORT_SYMBOL_GPL(x509_request_asymmetric_key);
Mimi Zohar3be4bea2013-08-20 14:36:27 -0400149
David Howellsc26fd692012-09-24 17:11:48 +0100150/*
David Howellsb426beb2013-08-30 16:18:02 +0100151 * Set up the signature parameters in an X.509 certificate. This involves
152 * digesting the signed data and extracting the signature.
David Howellsc26fd692012-09-24 17:11:48 +0100153 */
David Howellsb426beb2013-08-30 16:18:02 +0100154int x509_get_sig_params(struct x509_certificate *cert)
David Howellsc26fd692012-09-24 17:11:48 +0100155{
David Howellsc26fd692012-09-24 17:11:48 +0100156 struct crypto_shash *tfm;
157 struct shash_desc *desc;
158 size_t digest_size, desc_size;
David Howellsb426beb2013-08-30 16:18:02 +0100159 void *digest;
David Howellsc26fd692012-09-24 17:11:48 +0100160 int ret;
161
162 pr_devel("==>%s()\n", __func__);
David Howellsb426beb2013-08-30 16:18:02 +0100163
David Howells41559422014-09-16 17:36:15 +0100164 if (cert->unsupported_crypto)
165 return -ENOPKG;
Tadeusz Strukdb6c43b2016-02-02 10:08:53 -0800166 if (cert->sig.s)
David Howellsb426beb2013-08-30 16:18:02 +0100167 return 0;
168
Tadeusz Strukdb6c43b2016-02-02 10:08:53 -0800169 cert->sig.s = kmemdup(cert->raw_sig, cert->raw_sig_size,
170 GFP_KERNEL);
171 if (!cert->sig.s)
David Howellsb426beb2013-08-30 16:18:02 +0100172 return -ENOMEM;
Tadeusz Strukdb6c43b2016-02-02 10:08:53 -0800173
174 cert->sig.s_size = cert->raw_sig_size;
David Howellsb426beb2013-08-30 16:18:02 +0100175
David Howellsc26fd692012-09-24 17:11:48 +0100176 /* Allocate the hashing algorithm we're going to need and find out how
177 * big the hash operational data will be.
178 */
David Howells4e8ae722016-03-03 21:49:27 +0000179 tfm = crypto_alloc_shash(cert->sig.hash_algo, 0, 0);
David Howells41559422014-09-16 17:36:15 +0100180 if (IS_ERR(tfm)) {
181 if (PTR_ERR(tfm) == -ENOENT) {
182 cert->unsupported_crypto = true;
183 return -ENOPKG;
184 }
185 return PTR_ERR(tfm);
186 }
David Howellsc26fd692012-09-24 17:11:48 +0100187
188 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
189 digest_size = crypto_shash_digestsize(tfm);
190
David Howellsb426beb2013-08-30 16:18:02 +0100191 /* We allocate the hash operational data storage on the end of the
192 * digest storage space.
David Howellsc26fd692012-09-24 17:11:48 +0100193 */
194 ret = -ENOMEM;
Sowmini Varadhan271817a2015-10-19 17:23:28 -0400195 digest = kzalloc(ALIGN(digest_size, __alignof__(*desc)) + desc_size,
196 GFP_KERNEL);
David Howellsb426beb2013-08-30 16:18:02 +0100197 if (!digest)
198 goto error;
David Howellsc26fd692012-09-24 17:11:48 +0100199
David Howellsb426beb2013-08-30 16:18:02 +0100200 cert->sig.digest = digest;
201 cert->sig.digest_size = digest_size;
David Howellsc26fd692012-09-24 17:11:48 +0100202
Sowmini Varadhan271817a2015-10-19 17:23:28 -0400203 desc = PTR_ALIGN(digest + digest_size, __alignof__(*desc));
David Howellsb426beb2013-08-30 16:18:02 +0100204 desc->tfm = tfm;
205 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
David Howellsc26fd692012-09-24 17:11:48 +0100206
207 ret = crypto_shash_init(desc);
208 if (ret < 0)
209 goto error;
David Howellsb426beb2013-08-30 16:18:02 +0100210 might_sleep();
211 ret = crypto_shash_finup(desc, cert->tbs, cert->tbs_size, digest);
David Howellsc26fd692012-09-24 17:11:48 +0100212error:
David Howellsc26fd692012-09-24 17:11:48 +0100213 crypto_free_shash(tfm);
David Howellsc26fd692012-09-24 17:11:48 +0100214 pr_devel("<==%s() = %d\n", __func__, ret);
215 return ret;
216}
David Howellsb426beb2013-08-30 16:18:02 +0100217EXPORT_SYMBOL_GPL(x509_get_sig_params);
218
219/*
220 * Check the signature on a certificate using the provided public key
221 */
222int x509_check_signature(const struct public_key *pub,
223 struct x509_certificate *cert)
224{
225 int ret;
226
227 pr_devel("==>%s()\n", __func__);
228
229 ret = x509_get_sig_params(cert);
230 if (ret < 0)
231 return ret;
232
233 ret = public_key_verify_signature(pub, &cert->sig);
David Howells41559422014-09-16 17:36:15 +0100234 if (ret == -ENOPKG)
235 cert->unsupported_crypto = true;
David Howellsb426beb2013-08-30 16:18:02 +0100236 pr_debug("Cert Verification: %d\n", ret);
237 return ret;
238}
239EXPORT_SYMBOL_GPL(x509_check_signature);
David Howellsc26fd692012-09-24 17:11:48 +0100240
241/*
Mimi Zohar3be4bea2013-08-20 14:36:27 -0400242 * Check the new certificate against the ones in the trust keyring. If one of
243 * those is the signing key and validates the new certificate, then mark the
244 * new certificate as being trusted.
245 *
246 * Return 0 if the new certificate was successfully validated, 1 if we couldn't
247 * find a matching parent certificate in the trusted list and an error if there
248 * is a matching certificate but the signature check fails.
249 */
250static int x509_validate_trust(struct x509_certificate *cert,
251 struct key *trust_keyring)
252{
Mimi Zohar3be4bea2013-08-20 14:36:27 -0400253 struct key *key;
254 int ret = 1;
255
256 if (!trust_keyring)
257 return -EOPNOTSUPP;
258
David Howellsb92e6572015-07-20 21:16:26 +0100259 if (ca_keyid && !asymmetric_key_id_partial(cert->akid_skid, ca_keyid))
Dmitry Kasatkinffb70f62014-06-17 11:56:58 +0300260 return -EPERM;
261
David Howells4573b642015-07-20 21:16:26 +0100262 key = x509_request_asymmetric_key(trust_keyring,
263 cert->akid_id, cert->akid_skid,
Dmitry Kasatkinf1b731d2014-10-06 15:21:05 +0100264 false);
Mimi Zohar3be4bea2013-08-20 14:36:27 -0400265 if (!IS_ERR(key)) {
Dmitry Kasatkin32c47412014-06-17 11:56:59 +0300266 if (!use_builtin_keys
267 || test_bit(KEY_FLAG_BUILTIN, &key->flags))
David Howells146aa8b2015-10-21 14:04:48 +0100268 ret = x509_check_signature(key->payload.data[asym_crypto],
269 cert);
Mimi Zohar3be4bea2013-08-20 14:36:27 -0400270 key_put(key);
271 }
272 return ret;
273}
274
275/*
David Howellsc26fd692012-09-24 17:11:48 +0100276 * Attempt to parse a data blob for a key as an X509 certificate.
277 */
278static int x509_key_preparse(struct key_preparsed_payload *prep)
279{
David Howells46963b72014-09-16 17:36:13 +0100280 struct asymmetric_key_ids *kids;
David Howellsc26fd692012-09-24 17:11:48 +0100281 struct x509_certificate *cert;
David Howells46963b72014-09-16 17:36:13 +0100282 const char *q;
David Howellsc26fd692012-09-24 17:11:48 +0100283 size_t srlen, sulen;
David Howells46963b72014-09-16 17:36:13 +0100284 char *desc = NULL, *p;
David Howellsc26fd692012-09-24 17:11:48 +0100285 int ret;
286
287 cert = x509_cert_parse(prep->data, prep->datalen);
288 if (IS_ERR(cert))
289 return PTR_ERR(cert);
290
291 pr_devel("Cert Issuer: %s\n", cert->issuer);
292 pr_devel("Cert Subject: %s\n", cert->subject);
David Howells2ecdb232013-08-30 16:18:15 +0100293
David Howells4e8ae722016-03-03 21:49:27 +0000294 if (!cert->pub->pkey_algo ||
295 !cert->sig.pkey_algo ||
296 !cert->sig.hash_algo) {
David Howells2ecdb232013-08-30 16:18:15 +0100297 ret = -ENOPKG;
298 goto error_free_cert;
299 }
300
David Howells4e8ae722016-03-03 21:49:27 +0000301 pr_devel("Cert Key Algo: %s\n", cert->pub->pkey_algo);
David Howellsfd19a3d2015-07-29 16:58:32 +0100302 pr_devel("Cert Valid period: %lld-%lld\n", cert->valid_from, cert->valid_to);
Dmitry Kasatkinc7c8bb22013-04-25 10:43:56 +0300303 pr_devel("Cert Signature: %s + %s\n",
David Howells4e8ae722016-03-03 21:49:27 +0000304 cert->sig.pkey_algo,
305 cert->sig.hash_algo);
David Howellsc26fd692012-09-24 17:11:48 +0100306
David Howells4e8ae722016-03-03 21:49:27 +0000307 cert->pub->id_type = "X509";
David Howellsc26fd692012-09-24 17:11:48 +0100308
David Howells17334ca2013-08-30 16:18:31 +0100309 /* Check the signature on the key if it appears to be self-signed */
David Howells4573b642015-07-20 21:16:26 +0100310 if ((!cert->akid_skid && !cert->akid_id) ||
311 asymmetric_key_id_same(cert->skid, cert->akid_skid) ||
312 asymmetric_key_id_same(cert->id, cert->akid_id)) {
Mimi Zohar3be4bea2013-08-20 14:36:27 -0400313 ret = x509_check_signature(cert->pub, cert); /* self-signed */
David Howellsc26fd692012-09-24 17:11:48 +0100314 if (ret < 0)
315 goto error_free_cert;
Mimi Zohar3be4bea2013-08-20 14:36:27 -0400316 } else if (!prep->trusted) {
317 ret = x509_validate_trust(cert, get_system_trusted_keyring());
Petko Manolov41c89b62015-12-02 17:47:55 +0200318 if (ret)
319 ret = x509_validate_trust(cert, get_ima_mok_keyring());
Mimi Zohar3be4bea2013-08-20 14:36:27 -0400320 if (!ret)
321 prep->trusted = 1;
David Howellsc26fd692012-09-24 17:11:48 +0100322 }
323
324 /* Propose a description */
325 sulen = strlen(cert->subject);
David Howellsdd2f6c42014-10-03 16:17:02 +0100326 if (cert->raw_skid) {
327 srlen = cert->raw_skid_size;
328 q = cert->raw_skid;
329 } else {
330 srlen = cert->raw_serial_size;
331 q = cert->raw_serial;
332 }
David Howells46963b72014-09-16 17:36:13 +0100333
David Howellsc26fd692012-09-24 17:11:48 +0100334 ret = -ENOMEM;
David Howells46963b72014-09-16 17:36:13 +0100335 desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL);
David Howellsc26fd692012-09-24 17:11:48 +0100336 if (!desc)
337 goto error_free_cert;
David Howells46963b72014-09-16 17:36:13 +0100338 p = memcpy(desc, cert->subject, sulen);
339 p += sulen;
340 *p++ = ':';
341 *p++ = ' ';
342 p = bin2hex(p, q, srlen);
343 *p = 0;
344
345 kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL);
346 if (!kids)
347 goto error_free_desc;
348 kids->id[0] = cert->id;
349 kids->id[1] = cert->skid;
David Howellsc26fd692012-09-24 17:11:48 +0100350
351 /* We're pinning the module by being linked against it */
352 __module_get(public_key_subtype.owner);
David Howells146aa8b2015-10-21 14:04:48 +0100353 prep->payload.data[asym_subtype] = &public_key_subtype;
354 prep->payload.data[asym_key_ids] = kids;
355 prep->payload.data[asym_crypto] = cert->pub;
David Howellsc26fd692012-09-24 17:11:48 +0100356 prep->description = desc;
357 prep->quotalen = 100;
358
359 /* We've finished with the certificate */
360 cert->pub = NULL;
David Howells46963b72014-09-16 17:36:13 +0100361 cert->id = NULL;
362 cert->skid = NULL;
David Howellsc26fd692012-09-24 17:11:48 +0100363 desc = NULL;
364 ret = 0;
365
David Howells46963b72014-09-16 17:36:13 +0100366error_free_desc:
367 kfree(desc);
David Howellsc26fd692012-09-24 17:11:48 +0100368error_free_cert:
369 x509_free_certificate(cert);
370 return ret;
371}
372
373static struct asymmetric_key_parser x509_key_parser = {
374 .owner = THIS_MODULE,
375 .name = "x509",
376 .parse = x509_key_preparse,
377};
378
379/*
380 * Module stuff
381 */
382static int __init x509_key_init(void)
383{
384 return register_asymmetric_key_parser(&x509_key_parser);
385}
386
387static void __exit x509_key_exit(void)
388{
389 unregister_asymmetric_key_parser(&x509_key_parser);
390}
391
392module_init(x509_key_init);
393module_exit(x509_key_exit);
Konstantin Khlebnikove19aaa72013-09-17 15:14:55 +0400394
395MODULE_DESCRIPTION("X.509 certificate parser");
396MODULE_LICENSE("GPL");