blob: 06007f0e880c330903b5536e9d9c194da302738c [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>
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>
21#include <crypto/hash.h>
22#include "asymmetric_keys.h"
23#include "public_key.h"
24#include "x509_parser.h"
25
26static const
27struct public_key_algorithm *x509_public_key_algorithms[PKEY_ALGO__LAST] = {
28 [PKEY_ALGO_DSA] = NULL,
29#if defined(CONFIG_PUBLIC_KEY_ALGO_RSA) || \
30 defined(CONFIG_PUBLIC_KEY_ALGO_RSA_MODULE)
31 [PKEY_ALGO_RSA] = &RSA_public_key_algorithm,
32#endif
33};
34
35/*
36 * Check the signature on a certificate using the provided public key
37 */
38static int x509_check_signature(const struct public_key *pub,
39 const struct x509_certificate *cert)
40{
41 struct public_key_signature *sig;
42 struct crypto_shash *tfm;
43 struct shash_desc *desc;
44 size_t digest_size, desc_size;
45 int ret;
46
47 pr_devel("==>%s()\n", __func__);
48
49 /* Allocate the hashing algorithm we're going to need and find out how
50 * big the hash operational data will be.
51 */
52 tfm = crypto_alloc_shash(pkey_hash_algo[cert->sig_hash_algo], 0, 0);
53 if (IS_ERR(tfm))
54 return (PTR_ERR(tfm) == -ENOENT) ? -ENOPKG : PTR_ERR(tfm);
55
56 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
57 digest_size = crypto_shash_digestsize(tfm);
58
59 /* We allocate the hash operational data storage on the end of our
60 * context data.
61 */
62 ret = -ENOMEM;
63 sig = kzalloc(sizeof(*sig) + desc_size + digest_size, GFP_KERNEL);
64 if (!sig)
65 goto error_no_sig;
66
67 sig->pkey_hash_algo = cert->sig_hash_algo;
68 sig->digest = (u8 *)sig + sizeof(*sig) + desc_size;
69 sig->digest_size = digest_size;
70
71 desc = (void *)sig + sizeof(*sig);
72 desc->tfm = tfm;
73 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
74
75 ret = crypto_shash_init(desc);
76 if (ret < 0)
77 goto error;
78
79 ret = -ENOMEM;
80 sig->rsa.s = mpi_read_raw_data(cert->sig, cert->sig_size);
81 if (!sig->rsa.s)
82 goto error;
83
84 ret = crypto_shash_finup(desc, cert->tbs, cert->tbs_size, sig->digest);
85 if (ret < 0)
86 goto error_mpi;
87
88 ret = pub->algo->verify_signature(pub, sig);
89
90 pr_debug("Cert Verification: %d\n", ret);
91
92error_mpi:
93 mpi_free(sig->rsa.s);
94error:
95 kfree(sig);
96error_no_sig:
97 crypto_free_shash(tfm);
98
99 pr_devel("<==%s() = %d\n", __func__, ret);
100 return ret;
101}
102
103/*
104 * Attempt to parse a data blob for a key as an X509 certificate.
105 */
106static int x509_key_preparse(struct key_preparsed_payload *prep)
107{
108 struct x509_certificate *cert;
David Howellsa5752d12012-10-02 14:36:16 +0100109 struct tm now;
David Howellsc26fd692012-09-24 17:11:48 +0100110 size_t srlen, sulen;
111 char *desc = NULL;
112 int ret;
113
114 cert = x509_cert_parse(prep->data, prep->datalen);
115 if (IS_ERR(cert))
116 return PTR_ERR(cert);
117
118 pr_devel("Cert Issuer: %s\n", cert->issuer);
119 pr_devel("Cert Subject: %s\n", cert->subject);
120 pr_devel("Cert Key Algo: %s\n", pkey_algo[cert->pkey_algo]);
David Howells2f1c4fe2012-10-04 14:21:23 +0100121 pr_devel("Cert Valid From: %04ld-%02d-%02d %02d:%02d:%02d\n",
David Howellsa5752d12012-10-02 14:36:16 +0100122 cert->valid_from.tm_year + 1900, cert->valid_from.tm_mon + 1,
123 cert->valid_from.tm_mday, cert->valid_from.tm_hour,
124 cert->valid_from.tm_min, cert->valid_from.tm_sec);
David Howells2f1c4fe2012-10-04 14:21:23 +0100125 pr_devel("Cert Valid To: %04ld-%02d-%02d %02d:%02d:%02d\n",
David Howellsa5752d12012-10-02 14:36:16 +0100126 cert->valid_to.tm_year + 1900, cert->valid_to.tm_mon + 1,
127 cert->valid_to.tm_mday, cert->valid_to.tm_hour,
128 cert->valid_to.tm_min, cert->valid_to.tm_sec);
David Howellsc26fd692012-09-24 17:11:48 +0100129 pr_devel("Cert Signature: %s + %s\n",
130 pkey_algo[cert->sig_pkey_algo],
131 pkey_hash_algo[cert->sig_hash_algo]);
132
133 if (!cert->fingerprint || !cert->authority) {
134 pr_warn("Cert for '%s' must have SubjKeyId and AuthKeyId extensions\n",
135 cert->subject);
136 ret = -EKEYREJECTED;
137 goto error_free_cert;
138 }
139
David Howellsa5752d12012-10-02 14:36:16 +0100140 time_to_tm(CURRENT_TIME.tv_sec, 0, &now);
David Howells2f1c4fe2012-10-04 14:21:23 +0100141 pr_devel("Now: %04ld-%02d-%02d %02d:%02d:%02d\n",
David Howellsa5752d12012-10-02 14:36:16 +0100142 now.tm_year + 1900, now.tm_mon + 1, now.tm_mday,
143 now.tm_hour, now.tm_min, now.tm_sec);
144 if (now.tm_year < cert->valid_from.tm_year ||
145 (now.tm_year == cert->valid_from.tm_year &&
146 (now.tm_mon < cert->valid_from.tm_mon ||
147 (now.tm_mon == cert->valid_from.tm_mon &&
148 (now.tm_mday < cert->valid_from.tm_mday ||
149 (now.tm_mday == cert->valid_from.tm_mday &&
150 (now.tm_hour < cert->valid_from.tm_hour ||
151 (now.tm_hour == cert->valid_from.tm_hour &&
152 (now.tm_min < cert->valid_from.tm_min ||
153 (now.tm_min == cert->valid_from.tm_min &&
154 (now.tm_sec < cert->valid_from.tm_sec
155 ))))))))))) {
David Howellsc26fd692012-09-24 17:11:48 +0100156 pr_warn("Cert %s is not yet valid\n", cert->fingerprint);
157 ret = -EKEYREJECTED;
158 goto error_free_cert;
159 }
David Howellsa5752d12012-10-02 14:36:16 +0100160 if (now.tm_year > cert->valid_to.tm_year ||
161 (now.tm_year == cert->valid_to.tm_year &&
162 (now.tm_mon > cert->valid_to.tm_mon ||
163 (now.tm_mon == cert->valid_to.tm_mon &&
164 (now.tm_mday > cert->valid_to.tm_mday ||
165 (now.tm_mday == cert->valid_to.tm_mday &&
166 (now.tm_hour > cert->valid_to.tm_hour ||
167 (now.tm_hour == cert->valid_to.tm_hour &&
168 (now.tm_min > cert->valid_to.tm_min ||
169 (now.tm_min == cert->valid_to.tm_min &&
170 (now.tm_sec > cert->valid_to.tm_sec
171 ))))))))))) {
David Howellsc26fd692012-09-24 17:11:48 +0100172 pr_warn("Cert %s has expired\n", cert->fingerprint);
173 ret = -EKEYEXPIRED;
174 goto error_free_cert;
175 }
176
177 cert->pub->algo = x509_public_key_algorithms[cert->pkey_algo];
178 cert->pub->id_type = PKEY_ID_X509;
179
180 /* Check the signature on the key */
181 if (strcmp(cert->fingerprint, cert->authority) == 0) {
182 ret = x509_check_signature(cert->pub, cert);
183 if (ret < 0)
184 goto error_free_cert;
185 }
186
187 /* Propose a description */
188 sulen = strlen(cert->subject);
189 srlen = strlen(cert->fingerprint);
190 ret = -ENOMEM;
191 desc = kmalloc(sulen + 2 + srlen + 1, GFP_KERNEL);
192 if (!desc)
193 goto error_free_cert;
194 memcpy(desc, cert->subject, sulen);
195 desc[sulen] = ':';
196 desc[sulen + 1] = ' ';
197 memcpy(desc + sulen + 2, cert->fingerprint, srlen);
198 desc[sulen + 2 + srlen] = 0;
199
200 /* We're pinning the module by being linked against it */
201 __module_get(public_key_subtype.owner);
202 prep->type_data[0] = &public_key_subtype;
203 prep->type_data[1] = cert->fingerprint;
204 prep->payload = cert->pub;
205 prep->description = desc;
206 prep->quotalen = 100;
207
208 /* We've finished with the certificate */
209 cert->pub = NULL;
210 cert->fingerprint = NULL;
211 desc = NULL;
212 ret = 0;
213
214error_free_cert:
215 x509_free_certificate(cert);
216 return ret;
217}
218
219static struct asymmetric_key_parser x509_key_parser = {
220 .owner = THIS_MODULE,
221 .name = "x509",
222 .parse = x509_key_preparse,
223};
224
225/*
226 * Module stuff
227 */
228static int __init x509_key_init(void)
229{
230 return register_asymmetric_key_parser(&x509_key_parser);
231}
232
233static void __exit x509_key_exit(void)
234{
235 unregister_asymmetric_key_parser(&x509_key_parser);
236}
237
238module_init(x509_key_init);
239module_exit(x509_key_exit);