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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 if (!cert->pub->pkey_algo)
34 cert->unsupported_key = true;
35
36 if (!sig->pkey_algo)
37 cert->unsupported_sig = true;
38
39 /* We check the hash if we can - even if we can't then verify it */
40 if (!sig->hash_algo) {
41 cert->unsupported_sig = true;
42 return 0;
43 }
44
45 sig->s = kmemdup(cert->raw_sig, cert->raw_sig_size, GFP_KERNEL);
46 if (!sig->s)
47 return -ENOMEM;
48
49 sig->s_size = cert->raw_sig_size;
50
51 /* Allocate the hashing algorithm we're going to need and find out how
52 * big the hash operational data will be.
53 */
54 tfm = crypto_alloc_shash(sig->hash_algo, 0, 0);
55 if (IS_ERR(tfm)) {
56 if (PTR_ERR(tfm) == -ENOENT) {
57 cert->unsupported_sig = true;
58 return 0;
59 }
60 return PTR_ERR(tfm);
61 }
62
63 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
64 sig->digest_size = crypto_shash_digestsize(tfm);
65
66 ret = -ENOMEM;
67 sig->digest = kmalloc(sig->digest_size, GFP_KERNEL);
68 if (!sig->digest)
69 goto error;
70
71 desc = kzalloc(desc_size, GFP_KERNEL);
72 if (!desc)
73 goto error;
74
75 desc->tfm = tfm;
76
77 ret = crypto_shash_digest(desc, cert->tbs, cert->tbs_size, sig->digest);
78 if (ret < 0)
79 goto error_2;
80
81 ret = is_hash_blacklisted(sig->digest, sig->digest_size, "tbs");
82 if (ret == -EKEYREJECTED) {
83 pr_err("Cert %*phN is blacklisted\n",
84 sig->digest_size, sig->digest);
85 cert->blacklisted = true;
86 ret = 0;
87 }
88
89error_2:
90 kfree(desc);
91error:
92 crypto_free_shash(tfm);
93 pr_devel("<==%s() = %d\n", __func__, ret);
94 return ret;
95}
96
97/*
98 * Check for self-signedness in an X.509 cert and if found, check the signature
99 * immediately if we can.
100 */
101int x509_check_for_self_signed(struct x509_certificate *cert)
102{
103 int ret = 0;
104
105 pr_devel("==>%s()\n", __func__);
106
107 if (cert->raw_subject_size != cert->raw_issuer_size ||
108 memcmp(cert->raw_subject, cert->raw_issuer,
109 cert->raw_issuer_size) != 0)
110 goto not_self_signed;
111
112 if (cert->sig->auth_ids[0] || cert->sig->auth_ids[1]) {
113 /* If the AKID is present it may have one or two parts. If
114 * both are supplied, both must match.
115 */
116 bool a = asymmetric_key_id_same(cert->skid, cert->sig->auth_ids[1]);
117 bool b = asymmetric_key_id_same(cert->id, cert->sig->auth_ids[0]);
118
119 if (!a && !b)
120 goto not_self_signed;
121
122 ret = -EKEYREJECTED;
123 if (((a && !b) || (b && !a)) &&
124 cert->sig->auth_ids[0] && cert->sig->auth_ids[1])
125 goto out;
126 }
127
128 ret = -EKEYREJECTED;
129 if (strcmp(cert->pub->pkey_algo, cert->sig->pkey_algo) != 0)
130 goto out;
131
132 ret = public_key_verify_signature(cert->pub, cert->sig);
133 if (ret < 0) {
134 if (ret == -ENOPKG) {
135 cert->unsupported_sig = true;
136 ret = 0;
137 }
138 goto out;
139 }
140
141 pr_devel("Cert Self-signature verified");
142 cert->self_signed = true;
143
144out:
145 pr_devel("<==%s() = %d\n", __func__, ret);
146 return ret;
147
148not_self_signed:
149 pr_devel("<==%s() = 0 [not]\n", __func__);
150 return 0;
151}
152
153/*
154 * Attempt to parse a data blob for a key as an X509 certificate.
155 */
156static int x509_key_preparse(struct key_preparsed_payload *prep)
157{
158 struct asymmetric_key_ids *kids;
159 struct x509_certificate *cert;
160 const char *q;
161 size_t srlen, sulen;
162 char *desc = NULL, *p;
163 int ret;
164
165 cert = x509_cert_parse(prep->data, prep->datalen);
166 if (IS_ERR(cert))
167 return PTR_ERR(cert);
168
169 pr_devel("Cert Issuer: %s\n", cert->issuer);
170 pr_devel("Cert Subject: %s\n", cert->subject);
171
172 if (cert->unsupported_key) {
173 ret = -ENOPKG;
174 goto error_free_cert;
175 }
176
177 pr_devel("Cert Key Algo: %s\n", cert->pub->pkey_algo);
178 pr_devel("Cert Valid period: %lld-%lld\n", cert->valid_from, cert->valid_to);
179
180 cert->pub->id_type = "X509";
181
182 if (cert->unsupported_sig) {
183 public_key_signature_free(cert->sig);
184 cert->sig = NULL;
185 } else {
186 pr_devel("Cert Signature: %s + %s\n",
187 cert->sig->pkey_algo, cert->sig->hash_algo);
188 }
189
190 /* Don't permit addition of blacklisted keys */
191 ret = -EKEYREJECTED;
192 if (cert->blacklisted)
193 goto error_free_cert;
194
195 /* Propose a description */
196 sulen = strlen(cert->subject);
197 if (cert->raw_skid) {
198 srlen = cert->raw_skid_size;
199 q = cert->raw_skid;
200 } else {
201 srlen = cert->raw_serial_size;
202 q = cert->raw_serial;
203 }
204
205 ret = -ENOMEM;
206 desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL);
207 if (!desc)
208 goto error_free_cert;
209 p = memcpy(desc, cert->subject, sulen);
210 p += sulen;
211 *p++ = ':';
212 *p++ = ' ';
213 p = bin2hex(p, q, srlen);
214 *p = 0;
215
216 kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL);
217 if (!kids)
218 goto error_free_desc;
219 kids->id[0] = cert->id;
220 kids->id[1] = cert->skid;
221
222 /* We're pinning the module by being linked against it */
223 __module_get(public_key_subtype.owner);
224 prep->payload.data[asym_subtype] = &public_key_subtype;
225 prep->payload.data[asym_key_ids] = kids;
226 prep->payload.data[asym_crypto] = cert->pub;
227 prep->payload.data[asym_auth] = cert->sig;
228 prep->description = desc;
229 prep->quotalen = 100;
230
231 /* We've finished with the certificate */
232 cert->pub = NULL;
233 cert->id = NULL;
234 cert->skid = NULL;
235 cert->sig = NULL;
236 desc = NULL;
237 ret = 0;
238
239error_free_desc:
240 kfree(desc);
241error_free_cert:
242 x509_free_certificate(cert);
243 return ret;
244}
245
246static struct asymmetric_key_parser x509_key_parser = {
247 .owner = THIS_MODULE,
248 .name = "x509",
249 .parse = x509_key_preparse,
250};
251
252/*
253 * Module stuff
254 */
255static int __init x509_key_init(void)
256{
257 return register_asymmetric_key_parser(&x509_key_parser);
258}
259
260static void __exit x509_key_exit(void)
261{
262 unregister_asymmetric_key_parser(&x509_key_parser);
263}
264
265module_init(x509_key_init);
266module_exit(x509_key_exit);
267
268MODULE_DESCRIPTION("X.509 certificate parser");
269MODULE_AUTHOR("Red Hat, Inc.");
270MODULE_LICENSE("GPL");
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 <keys/asymmetric-subtype.h>
17#include <keys/asymmetric-parser.h>
18#include <keys/system_keyring.h>
19#include <crypto/hash.h>
20#include "asymmetric_keys.h"
21#include "x509_parser.h"
22
23/*
24 * Set up the signature parameters in an X.509 certificate. This involves
25 * digesting the signed data and extracting the signature.
26 */
27int x509_get_sig_params(struct x509_certificate *cert)
28{
29 struct public_key_signature *sig = cert->sig;
30 struct crypto_shash *tfm;
31 struct shash_desc *desc;
32 size_t desc_size;
33 int ret;
34
35 pr_devel("==>%s()\n", __func__);
36
37 if (!cert->pub->pkey_algo)
38 cert->unsupported_key = true;
39
40 if (!sig->pkey_algo)
41 cert->unsupported_sig = true;
42
43 /* We check the hash if we can - even if we can't then verify it */
44 if (!sig->hash_algo) {
45 cert->unsupported_sig = true;
46 return 0;
47 }
48
49 sig->s = kmemdup(cert->raw_sig, cert->raw_sig_size, GFP_KERNEL);
50 if (!sig->s)
51 return -ENOMEM;
52
53 sig->s_size = cert->raw_sig_size;
54
55 /* Allocate the hashing algorithm we're going to need and find out how
56 * big the hash operational data will be.
57 */
58 tfm = crypto_alloc_shash(sig->hash_algo, 0, 0);
59 if (IS_ERR(tfm)) {
60 if (PTR_ERR(tfm) == -ENOENT) {
61 cert->unsupported_sig = true;
62 return 0;
63 }
64 return PTR_ERR(tfm);
65 }
66
67 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
68 sig->digest_size = crypto_shash_digestsize(tfm);
69
70 ret = -ENOMEM;
71 sig->digest = kmalloc(sig->digest_size, GFP_KERNEL);
72 if (!sig->digest)
73 goto error;
74
75 desc = kzalloc(desc_size, GFP_KERNEL);
76 if (!desc)
77 goto error;
78
79 desc->tfm = tfm;
80 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
81
82 ret = crypto_shash_digest(desc, cert->tbs, cert->tbs_size, sig->digest);
83 if (ret < 0)
84 goto error_2;
85
86 ret = is_hash_blacklisted(sig->digest, sig->digest_size, "tbs");
87 if (ret == -EKEYREJECTED) {
88 pr_err("Cert %*phN is blacklisted\n",
89 sig->digest_size, sig->digest);
90 cert->blacklisted = true;
91 ret = 0;
92 }
93
94error_2:
95 kfree(desc);
96error:
97 crypto_free_shash(tfm);
98 pr_devel("<==%s() = %d\n", __func__, ret);
99 return ret;
100}
101
102/*
103 * Check for self-signedness in an X.509 cert and if found, check the signature
104 * immediately if we can.
105 */
106int x509_check_for_self_signed(struct x509_certificate *cert)
107{
108 int ret = 0;
109
110 pr_devel("==>%s()\n", __func__);
111
112 if (cert->raw_subject_size != cert->raw_issuer_size ||
113 memcmp(cert->raw_subject, cert->raw_issuer,
114 cert->raw_issuer_size) != 0)
115 goto not_self_signed;
116
117 if (cert->sig->auth_ids[0] || cert->sig->auth_ids[1]) {
118 /* If the AKID is present it may have one or two parts. If
119 * both are supplied, both must match.
120 */
121 bool a = asymmetric_key_id_same(cert->skid, cert->sig->auth_ids[1]);
122 bool b = asymmetric_key_id_same(cert->id, cert->sig->auth_ids[0]);
123
124 if (!a && !b)
125 goto not_self_signed;
126
127 ret = -EKEYREJECTED;
128 if (((a && !b) || (b && !a)) &&
129 cert->sig->auth_ids[0] && cert->sig->auth_ids[1])
130 goto out;
131 }
132
133 ret = -EKEYREJECTED;
134 if (strcmp(cert->pub->pkey_algo, cert->sig->pkey_algo) != 0)
135 goto out;
136
137 ret = public_key_verify_signature(cert->pub, cert->sig);
138 if (ret < 0) {
139 if (ret == -ENOPKG) {
140 cert->unsupported_sig = true;
141 ret = 0;
142 }
143 goto out;
144 }
145
146 pr_devel("Cert Self-signature verified");
147 cert->self_signed = true;
148
149out:
150 pr_devel("<==%s() = %d\n", __func__, ret);
151 return ret;
152
153not_self_signed:
154 pr_devel("<==%s() = 0 [not]\n", __func__);
155 return 0;
156}
157
158/*
159 * Attempt to parse a data blob for a key as an X509 certificate.
160 */
161static int x509_key_preparse(struct key_preparsed_payload *prep)
162{
163 struct asymmetric_key_ids *kids;
164 struct x509_certificate *cert;
165 const char *q;
166 size_t srlen, sulen;
167 char *desc = NULL, *p;
168 int ret;
169
170 cert = x509_cert_parse(prep->data, prep->datalen);
171 if (IS_ERR(cert))
172 return PTR_ERR(cert);
173
174 pr_devel("Cert Issuer: %s\n", cert->issuer);
175 pr_devel("Cert Subject: %s\n", cert->subject);
176
177 if (cert->unsupported_key) {
178 ret = -ENOPKG;
179 goto error_free_cert;
180 }
181
182 pr_devel("Cert Key Algo: %s\n", cert->pub->pkey_algo);
183 pr_devel("Cert Valid period: %lld-%lld\n", cert->valid_from, cert->valid_to);
184
185 cert->pub->id_type = "X509";
186
187 if (cert->unsupported_sig) {
188 public_key_signature_free(cert->sig);
189 cert->sig = NULL;
190 } else {
191 pr_devel("Cert Signature: %s + %s\n",
192 cert->sig->pkey_algo, cert->sig->hash_algo);
193 }
194
195 /* Don't permit addition of blacklisted keys */
196 ret = -EKEYREJECTED;
197 if (cert->blacklisted)
198 goto error_free_cert;
199
200 /* Propose a description */
201 sulen = strlen(cert->subject);
202 if (cert->raw_skid) {
203 srlen = cert->raw_skid_size;
204 q = cert->raw_skid;
205 } else {
206 srlen = cert->raw_serial_size;
207 q = cert->raw_serial;
208 }
209
210 ret = -ENOMEM;
211 desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL);
212 if (!desc)
213 goto error_free_cert;
214 p = memcpy(desc, cert->subject, sulen);
215 p += sulen;
216 *p++ = ':';
217 *p++ = ' ';
218 p = bin2hex(p, q, srlen);
219 *p = 0;
220
221 kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL);
222 if (!kids)
223 goto error_free_desc;
224 kids->id[0] = cert->id;
225 kids->id[1] = cert->skid;
226
227 /* We're pinning the module by being linked against it */
228 __module_get(public_key_subtype.owner);
229 prep->payload.data[asym_subtype] = &public_key_subtype;
230 prep->payload.data[asym_key_ids] = kids;
231 prep->payload.data[asym_crypto] = cert->pub;
232 prep->payload.data[asym_auth] = cert->sig;
233 prep->description = desc;
234 prep->quotalen = 100;
235
236 /* We've finished with the certificate */
237 cert->pub = NULL;
238 cert->id = NULL;
239 cert->skid = NULL;
240 cert->sig = NULL;
241 desc = NULL;
242 ret = 0;
243
244error_free_desc:
245 kfree(desc);
246error_free_cert:
247 x509_free_certificate(cert);
248 return ret;
249}
250
251static struct asymmetric_key_parser x509_key_parser = {
252 .owner = THIS_MODULE,
253 .name = "x509",
254 .parse = x509_key_preparse,
255};
256
257/*
258 * Module stuff
259 */
260static int __init x509_key_init(void)
261{
262 return register_asymmetric_key_parser(&x509_key_parser);
263}
264
265static void __exit x509_key_exit(void)
266{
267 unregister_asymmetric_key_parser(&x509_key_parser);
268}
269
270module_init(x509_key_init);
271module_exit(x509_key_exit);
272
273MODULE_DESCRIPTION("X.509 certificate parser");
274MODULE_AUTHOR("Red Hat, Inc.");
275MODULE_LICENSE("GPL");