1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Instantiate a public key crypto key from an X.509 Certificate
4 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
8 #define pr_fmt(fmt) "X.509: "fmt
9 #include <crypto/hash.h>
10 #include <crypto/sm2.h>
11 #include <keys/asymmetric-parser.h>
12 #include <keys/asymmetric-subtype.h>
13 #include <keys/system_keyring.h>
14 #include <linux/module.h>
15 #include <linux/kernel.h>
16 #include <linux/slab.h>
17 #include <linux/string.h>
18 #include "asymmetric_keys.h"
19 #include "x509_parser.h"
22 * Set up the signature parameters in an X.509 certificate. This involves
23 * digesting the signed data and extracting the signature.
25 int x509_get_sig_params(struct x509_certificate *cert)
27 struct public_key_signature *sig = cert->sig;
28 struct crypto_shash *tfm;
29 struct shash_desc *desc;
33 pr_devel("==>%s()\n", __func__);
35 sig->s = kmemdup(cert->raw_sig, cert->raw_sig_size, GFP_KERNEL);
39 sig->s_size = cert->raw_sig_size;
41 /* Allocate the hashing algorithm we're going to need and find out how
42 * big the hash operational data will be.
44 tfm = crypto_alloc_shash(sig->hash_algo, 0, 0);
46 if (PTR_ERR(tfm) == -ENOENT) {
47 cert->unsupported_sig = true;
53 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
54 sig->digest_size = crypto_shash_digestsize(tfm);
57 sig->digest = kmalloc(sig->digest_size, GFP_KERNEL);
61 desc = kzalloc(desc_size, GFP_KERNEL);
67 if (strcmp(cert->pub->pkey_algo, "sm2") == 0) {
68 ret = strcmp(sig->hash_algo, "sm3") != 0 ? -EINVAL :
69 crypto_shash_init(desc) ?:
70 sm2_compute_z_digest(desc, cert->pub->key,
71 cert->pub->keylen, sig->digest) ?:
72 crypto_shash_init(desc) ?:
73 crypto_shash_update(desc, sig->digest,
75 crypto_shash_finup(desc, cert->tbs, cert->tbs_size,
78 ret = crypto_shash_digest(desc, cert->tbs, cert->tbs_size,
85 ret = is_hash_blacklisted(sig->digest, sig->digest_size,
86 BLACKLIST_HASH_X509_TBS);
87 if (ret == -EKEYREJECTED) {
88 pr_err("Cert %*phN is blacklisted\n",
89 sig->digest_size, sig->digest);
90 cert->blacklisted = true;
97 crypto_free_shash(tfm);
98 pr_devel("<==%s() = %d\n", __func__, ret);
103 * Check for self-signedness in an X.509 cert and if found, check the signature
104 * immediately if we can.
106 int x509_check_for_self_signed(struct x509_certificate *cert)
110 pr_devel("==>%s()\n", __func__);
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;
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.
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]);
125 goto not_self_signed;
128 if (((a && !b) || (b && !a)) &&
129 cert->sig->auth_ids[0] && cert->sig->auth_ids[1])
133 if (cert->unsupported_sig) {
138 ret = public_key_verify_signature(cert->pub, cert->sig);
140 if (ret == -ENOPKG) {
141 cert->unsupported_sig = true;
147 pr_devel("Cert Self-signature verified");
148 cert->self_signed = true;
151 pr_devel("<==%s() = %d\n", __func__, ret);
155 pr_devel("<==%s() = 0 [not]\n", __func__);
160 * Attempt to parse a data blob for a key as an X509 certificate.
162 static int x509_key_preparse(struct key_preparsed_payload *prep)
164 struct asymmetric_key_ids *kids;
165 struct x509_certificate *cert;
168 char *desc = NULL, *p;
171 cert = x509_cert_parse(prep->data, prep->datalen);
173 return PTR_ERR(cert);
175 pr_devel("Cert Issuer: %s\n", cert->issuer);
176 pr_devel("Cert Subject: %s\n", cert->subject);
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);
180 cert->pub->id_type = "X509";
182 if (cert->unsupported_sig) {
183 public_key_signature_free(cert->sig);
186 pr_devel("Cert Signature: %s + %s\n",
187 cert->sig->pkey_algo, cert->sig->hash_algo);
190 /* Don't permit addition of blacklisted keys */
192 if (cert->blacklisted)
193 goto error_free_cert;
195 /* Propose a description */
196 sulen = strlen(cert->subject);
197 if (cert->raw_skid) {
198 srlen = cert->raw_skid_size;
201 srlen = cert->raw_serial_size;
202 q = cert->raw_serial;
206 desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL);
208 goto error_free_cert;
209 p = memcpy(desc, cert->subject, sulen);
213 p = bin2hex(p, q, srlen);
216 kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL);
218 goto error_free_desc;
219 kids->id[0] = cert->id;
220 kids->id[1] = cert->skid;
221 kids->id[2] = asymmetric_key_generate_id(cert->raw_subject,
222 cert->raw_subject_size,
224 if (IS_ERR(kids->id[2])) {
225 ret = PTR_ERR(kids->id[2]);
226 goto error_free_kids;
229 /* We're pinning the module by being linked against it */
230 __module_get(public_key_subtype.owner);
231 prep->payload.data[asym_subtype] = &public_key_subtype;
232 prep->payload.data[asym_key_ids] = kids;
233 prep->payload.data[asym_crypto] = cert->pub;
234 prep->payload.data[asym_auth] = cert->sig;
235 prep->description = desc;
236 prep->quotalen = 100;
238 /* We've finished with the certificate */
252 x509_free_certificate(cert);
256 static struct asymmetric_key_parser x509_key_parser = {
257 .owner = THIS_MODULE,
259 .parse = x509_key_preparse,
265 static int __init x509_key_init(void)
267 return register_asymmetric_key_parser(&x509_key_parser);
270 static void __exit x509_key_exit(void)
272 unregister_asymmetric_key_parser(&x509_key_parser);
275 module_init(x509_key_init);
276 module_exit(x509_key_exit);
278 MODULE_DESCRIPTION("X.509 certificate parser");
279 MODULE_AUTHOR("Red Hat, Inc.");
280 MODULE_LICENSE("GPL");