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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>
21#include <crypto/hash.h>
22#include "asymmetric_keys.h"
23#include "public_key.h"
24#include "x509_parser.h"
25
26/*
27 * Set up the signature parameters in an X.509 certificate. This involves
28 * digesting the signed data and extracting the signature.
29 */
30int x509_get_sig_params(struct x509_certificate *cert)
31{
32 struct crypto_shash *tfm;
33 struct shash_desc *desc;
34 size_t digest_size, desc_size;
35 void *digest;
36 int ret;
37
38 pr_devel("==>%s()\n", __func__);
39
40 if (cert->sig.rsa.s)
41 return 0;
42
43 cert->sig.rsa.s = mpi_read_raw_data(cert->raw_sig, cert->raw_sig_size);
44 if (!cert->sig.rsa.s)
45 return -ENOMEM;
46 cert->sig.nr_mpi = 1;
47
48 /* Allocate the hashing algorithm we're going to need and find out how
49 * big the hash operational data will be.
50 */
51 tfm = crypto_alloc_shash(hash_algo_name[cert->sig.pkey_hash_algo], 0, 0);
52 if (IS_ERR(tfm))
53 return (PTR_ERR(tfm) == -ENOENT) ? -ENOPKG : PTR_ERR(tfm);
54
55 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
56 digest_size = crypto_shash_digestsize(tfm);
57
58 /* We allocate the hash operational data storage on the end of the
59 * digest storage space.
60 */
61 ret = -ENOMEM;
62 digest = kzalloc(digest_size + desc_size, GFP_KERNEL);
63 if (!digest)
64 goto error;
65
66 cert->sig.digest = digest;
67 cert->sig.digest_size = digest_size;
68
69 desc = digest + digest_size;
70 desc->tfm = tfm;
71 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
72
73 ret = crypto_shash_init(desc);
74 if (ret < 0)
75 goto error;
76 might_sleep();
77 ret = crypto_shash_finup(desc, cert->tbs, cert->tbs_size, digest);
78error:
79 crypto_free_shash(tfm);
80 pr_devel("<==%s() = %d\n", __func__, ret);
81 return ret;
82}
83EXPORT_SYMBOL_GPL(x509_get_sig_params);
84
85/*
86 * Check the signature on a certificate using the provided public key
87 */
88int x509_check_signature(const struct public_key *pub,
89 struct x509_certificate *cert)
90{
91 int ret;
92
93 pr_devel("==>%s()\n", __func__);
94
95 ret = x509_get_sig_params(cert);
96 if (ret < 0)
97 return ret;
98
99 ret = public_key_verify_signature(pub, &cert->sig);
100 pr_debug("Cert Verification: %d\n", ret);
101 return ret;
102}
103EXPORT_SYMBOL_GPL(x509_check_signature);
104
105/*
106 * Attempt to parse a data blob for a key as an X509 certificate.
107 */
108static int x509_key_preparse(struct key_preparsed_payload *prep)
109{
110 struct x509_certificate *cert;
111 size_t srlen, sulen;
112 char *desc = NULL;
113 int ret;
114
115 cert = x509_cert_parse(prep->data, prep->datalen);
116 if (IS_ERR(cert))
117 return PTR_ERR(cert);
118
119 pr_devel("Cert Issuer: %s\n", cert->issuer);
120 pr_devel("Cert Subject: %s\n", cert->subject);
121
122 if (cert->pub->pkey_algo >= PKEY_ALGO__LAST ||
123 cert->sig.pkey_algo >= PKEY_ALGO__LAST ||
124 cert->sig.pkey_hash_algo >= PKEY_HASH__LAST ||
125 !pkey_algo[cert->pub->pkey_algo] ||
126 !pkey_algo[cert->sig.pkey_algo] ||
127 !hash_algo_name[cert->sig.pkey_hash_algo]) {
128 ret = -ENOPKG;
129 goto error_free_cert;
130 }
131
132 pr_devel("Cert Key Algo: %s\n", pkey_algo_name[cert->pub->pkey_algo]);
133 pr_devel("Cert Valid From: %04ld-%02d-%02d %02d:%02d:%02d\n",
134 cert->valid_from.tm_year + 1900, cert->valid_from.tm_mon + 1,
135 cert->valid_from.tm_mday, cert->valid_from.tm_hour,
136 cert->valid_from.tm_min, cert->valid_from.tm_sec);
137 pr_devel("Cert Valid To: %04ld-%02d-%02d %02d:%02d:%02d\n",
138 cert->valid_to.tm_year + 1900, cert->valid_to.tm_mon + 1,
139 cert->valid_to.tm_mday, cert->valid_to.tm_hour,
140 cert->valid_to.tm_min, cert->valid_to.tm_sec);
141 pr_devel("Cert Signature: %s + %s\n",
142 pkey_algo_name[cert->sig.pkey_algo],
143 hash_algo_name[cert->sig.pkey_hash_algo]);
144
145 if (!cert->fingerprint) {
146 pr_warn("Cert for '%s' must have a SubjKeyId extension\n",
147 cert->subject);
148 ret = -EKEYREJECTED;
149 goto error_free_cert;
150 }
151
152 cert->pub->algo = pkey_algo[cert->pub->pkey_algo];
153 cert->pub->id_type = PKEY_ID_X509;
154
155 /* Check the signature on the key if it appears to be self-signed */
156 if (!cert->authority ||
157 strcmp(cert->fingerprint, cert->authority) == 0) {
158 ret = x509_check_signature(cert->pub, cert);
159 if (ret < 0)
160 goto error_free_cert;
161 }
162
163 /* Propose a description */
164 sulen = strlen(cert->subject);
165 srlen = strlen(cert->fingerprint);
166 ret = -ENOMEM;
167 desc = kmalloc(sulen + 2 + srlen + 1, GFP_KERNEL);
168 if (!desc)
169 goto error_free_cert;
170 memcpy(desc, cert->subject, sulen);
171 desc[sulen] = ':';
172 desc[sulen + 1] = ' ';
173 memcpy(desc + sulen + 2, cert->fingerprint, srlen);
174 desc[sulen + 2 + srlen] = 0;
175
176 /* We're pinning the module by being linked against it */
177 __module_get(public_key_subtype.owner);
178 prep->type_data[0] = &public_key_subtype;
179 prep->type_data[1] = cert->fingerprint;
180 prep->payload = cert->pub;
181 prep->description = desc;
182 prep->quotalen = 100;
183
184 /* We've finished with the certificate */
185 cert->pub = NULL;
186 cert->fingerprint = NULL;
187 desc = NULL;
188 ret = 0;
189
190error_free_cert:
191 x509_free_certificate(cert);
192 return ret;
193}
194
195static struct asymmetric_key_parser x509_key_parser = {
196 .owner = THIS_MODULE,
197 .name = "x509",
198 .parse = x509_key_preparse,
199};
200
201/*
202 * Module stuff
203 */
204static int __init x509_key_init(void)
205{
206 return register_asymmetric_key_parser(&x509_key_parser);
207}
208
209static void __exit x509_key_exit(void)
210{
211 unregister_asymmetric_key_parser(&x509_key_parser);
212}
213
214module_init(x509_key_init);
215module_exit(x509_key_exit);
216
217MODULE_DESCRIPTION("X.509 certificate parser");
218MODULE_LICENSE("GPL");
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Instantiate a public key crypto key from an X.509 Certificate
3 *
4 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#define pr_fmt(fmt) "X.509: "fmt
9#include <linux/module.h>
10#include <linux/kernel.h>
11#include <linux/slab.h>
12#include <keys/asymmetric-subtype.h>
13#include <keys/asymmetric-parser.h>
14#include <keys/system_keyring.h>
15#include <crypto/hash.h>
16#include "asymmetric_keys.h"
17#include "x509_parser.h"
18
19/*
20 * Set up the signature parameters in an X.509 certificate. This involves
21 * digesting the signed data and extracting the signature.
22 */
23int x509_get_sig_params(struct x509_certificate *cert)
24{
25 struct public_key_signature *sig = cert->sig;
26 struct crypto_shash *tfm;
27 struct shash_desc *desc;
28 size_t desc_size;
29 int ret;
30
31 pr_devel("==>%s()\n", __func__);
32
33 sig->data = cert->tbs;
34 sig->data_size = cert->tbs_size;
35
36 sig->s = kmemdup(cert->raw_sig, cert->raw_sig_size, GFP_KERNEL);
37 if (!sig->s)
38 return -ENOMEM;
39
40 sig->s_size = cert->raw_sig_size;
41
42 /* Allocate the hashing algorithm we're going to need and find out how
43 * big the hash operational data will be.
44 */
45 tfm = crypto_alloc_shash(sig->hash_algo, 0, 0);
46 if (IS_ERR(tfm)) {
47 if (PTR_ERR(tfm) == -ENOENT) {
48 cert->unsupported_sig = true;
49 return 0;
50 }
51 return PTR_ERR(tfm);
52 }
53
54 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
55 sig->digest_size = crypto_shash_digestsize(tfm);
56
57 ret = -ENOMEM;
58 sig->digest = kmalloc(sig->digest_size, GFP_KERNEL);
59 if (!sig->digest)
60 goto error;
61
62 desc = kzalloc(desc_size, GFP_KERNEL);
63 if (!desc)
64 goto error;
65
66 desc->tfm = tfm;
67
68 ret = crypto_shash_digest(desc, cert->tbs, cert->tbs_size, sig->digest);
69 if (ret < 0)
70 goto error_2;
71
72 ret = is_hash_blacklisted(sig->digest, sig->digest_size,
73 BLACKLIST_HASH_X509_TBS);
74 if (ret == -EKEYREJECTED) {
75 pr_err("Cert %*phN is blacklisted\n",
76 sig->digest_size, sig->digest);
77 cert->blacklisted = true;
78 ret = 0;
79 }
80
81error_2:
82 kfree(desc);
83error:
84 crypto_free_shash(tfm);
85 pr_devel("<==%s() = %d\n", __func__, ret);
86 return ret;
87}
88
89/*
90 * Check for self-signedness in an X.509 cert and if found, check the signature
91 * immediately if we can.
92 */
93int x509_check_for_self_signed(struct x509_certificate *cert)
94{
95 int ret = 0;
96
97 pr_devel("==>%s()\n", __func__);
98
99 if (cert->raw_subject_size != cert->raw_issuer_size ||
100 memcmp(cert->raw_subject, cert->raw_issuer,
101 cert->raw_issuer_size) != 0)
102 goto not_self_signed;
103
104 if (cert->sig->auth_ids[0] || cert->sig->auth_ids[1]) {
105 /* If the AKID is present it may have one or two parts. If
106 * both are supplied, both must match.
107 */
108 bool a = asymmetric_key_id_same(cert->skid, cert->sig->auth_ids[1]);
109 bool b = asymmetric_key_id_same(cert->id, cert->sig->auth_ids[0]);
110
111 if (!a && !b)
112 goto not_self_signed;
113
114 ret = -EKEYREJECTED;
115 if (((a && !b) || (b && !a)) &&
116 cert->sig->auth_ids[0] && cert->sig->auth_ids[1])
117 goto out;
118 }
119
120 ret = public_key_verify_signature(cert->pub, cert->sig);
121 if (ret < 0) {
122 if (ret == -ENOPKG) {
123 cert->unsupported_sig = true;
124 ret = 0;
125 }
126 goto out;
127 }
128
129 pr_devel("Cert Self-signature verified");
130 cert->self_signed = true;
131
132out:
133 pr_devel("<==%s() = %d\n", __func__, ret);
134 return ret;
135
136not_self_signed:
137 pr_devel("<==%s() = 0 [not]\n", __func__);
138 return 0;
139}
140
141/*
142 * Attempt to parse a data blob for a key as an X509 certificate.
143 */
144static int x509_key_preparse(struct key_preparsed_payload *prep)
145{
146 struct asymmetric_key_ids *kids;
147 struct x509_certificate *cert;
148 const char *q;
149 size_t srlen, sulen;
150 char *desc = NULL, *p;
151 int ret;
152
153 cert = x509_cert_parse(prep->data, prep->datalen);
154 if (IS_ERR(cert))
155 return PTR_ERR(cert);
156
157 pr_devel("Cert Issuer: %s\n", cert->issuer);
158 pr_devel("Cert Subject: %s\n", cert->subject);
159 pr_devel("Cert Key Algo: %s\n", cert->pub->pkey_algo);
160 pr_devel("Cert Valid period: %lld-%lld\n", cert->valid_from, cert->valid_to);
161
162 cert->pub->id_type = "X509";
163
164 if (cert->unsupported_sig) {
165 public_key_signature_free(cert->sig);
166 cert->sig = NULL;
167 } else {
168 pr_devel("Cert Signature: %s + %s\n",
169 cert->sig->pkey_algo, cert->sig->hash_algo);
170 }
171
172 /* Don't permit addition of blacklisted keys */
173 ret = -EKEYREJECTED;
174 if (cert->blacklisted)
175 goto error_free_cert;
176
177 /* Propose a description */
178 sulen = strlen(cert->subject);
179 if (cert->raw_skid) {
180 srlen = cert->raw_skid_size;
181 q = cert->raw_skid;
182 } else {
183 srlen = cert->raw_serial_size;
184 q = cert->raw_serial;
185 }
186
187 ret = -ENOMEM;
188 desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL);
189 if (!desc)
190 goto error_free_cert;
191 p = memcpy(desc, cert->subject, sulen);
192 p += sulen;
193 *p++ = ':';
194 *p++ = ' ';
195 p = bin2hex(p, q, srlen);
196 *p = 0;
197
198 kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL);
199 if (!kids)
200 goto error_free_desc;
201 kids->id[0] = cert->id;
202 kids->id[1] = cert->skid;
203 kids->id[2] = asymmetric_key_generate_id(cert->raw_subject,
204 cert->raw_subject_size,
205 "", 0);
206 if (IS_ERR(kids->id[2])) {
207 ret = PTR_ERR(kids->id[2]);
208 goto error_free_kids;
209 }
210
211 /* We're pinning the module by being linked against it */
212 __module_get(public_key_subtype.owner);
213 prep->payload.data[asym_subtype] = &public_key_subtype;
214 prep->payload.data[asym_key_ids] = kids;
215 prep->payload.data[asym_crypto] = cert->pub;
216 prep->payload.data[asym_auth] = cert->sig;
217 prep->description = desc;
218 prep->quotalen = 100;
219
220 /* We've finished with the certificate */
221 cert->pub = NULL;
222 cert->id = NULL;
223 cert->skid = NULL;
224 cert->sig = NULL;
225 desc = NULL;
226 kids = NULL;
227 ret = 0;
228
229error_free_kids:
230 kfree(kids);
231error_free_desc:
232 kfree(desc);
233error_free_cert:
234 x509_free_certificate(cert);
235 return ret;
236}
237
238static struct asymmetric_key_parser x509_key_parser = {
239 .owner = THIS_MODULE,
240 .name = "x509",
241 .parse = x509_key_preparse,
242};
243
244/*
245 * Module stuff
246 */
247extern int __init certs_selftest(void);
248static int __init x509_key_init(void)
249{
250 int ret;
251
252 ret = register_asymmetric_key_parser(&x509_key_parser);
253 if (ret < 0)
254 return ret;
255 return fips_signature_selftest();
256}
257
258static void __exit x509_key_exit(void)
259{
260 unregister_asymmetric_key_parser(&x509_key_parser);
261}
262
263module_init(x509_key_init);
264module_exit(x509_key_exit);
265
266MODULE_DESCRIPTION("X.509 certificate parser");
267MODULE_AUTHOR("Red Hat, Inc.");
268MODULE_LICENSE("GPL");