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 <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"
20 * Set up the signature parameters in an X.509 certificate. This involves
21 * digesting the signed data and extracting the signature.
23 int x509_get_sig_params(struct x509_certificate *cert)
25 struct public_key_signature *sig = cert->sig;
26 struct crypto_shash *tfm;
27 struct shash_desc *desc;
31 pr_devel("==>%s()\n", __func__);
33 if (!cert->pub->pkey_algo)
34 cert->unsupported_key = true;
37 cert->unsupported_sig = true;
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;
45 sig->s = kmemdup(cert->raw_sig, cert->raw_sig_size, GFP_KERNEL);
49 sig->s_size = cert->raw_sig_size;
51 /* Allocate the hashing algorithm we're going to need and find out how
52 * big the hash operational data will be.
54 tfm = crypto_alloc_shash(sig->hash_algo, 0, 0);
56 if (PTR_ERR(tfm) == -ENOENT) {
57 cert->unsupported_sig = true;
63 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
64 sig->digest_size = crypto_shash_digestsize(tfm);
67 sig->digest = kmalloc(sig->digest_size, GFP_KERNEL);
71 desc = kzalloc(desc_size, GFP_KERNEL);
77 ret = crypto_shash_digest(desc, cert->tbs, cert->tbs_size, sig->digest);
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;
92 crypto_free_shash(tfm);
93 pr_devel("<==%s() = %d\n", __func__, ret);
98 * Check for self-signedness in an X.509 cert and if found, check the signature
99 * immediately if we can.
101 int x509_check_for_self_signed(struct x509_certificate *cert)
105 pr_devel("==>%s()\n", __func__);
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;
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.
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]);
120 goto not_self_signed;
123 if (((a && !b) || (b && !a)) &&
124 cert->sig->auth_ids[0] && cert->sig->auth_ids[1])
129 if (strcmp(cert->pub->pkey_algo, cert->sig->pkey_algo) != 0)
132 ret = public_key_verify_signature(cert->pub, cert->sig);
134 if (ret == -ENOPKG) {
135 cert->unsupported_sig = true;
141 pr_devel("Cert Self-signature verified");
142 cert->self_signed = true;
145 pr_devel("<==%s() = %d\n", __func__, ret);
149 pr_devel("<==%s() = 0 [not]\n", __func__);
154 * Attempt to parse a data blob for a key as an X509 certificate.
156 static int x509_key_preparse(struct key_preparsed_payload *prep)
158 struct asymmetric_key_ids *kids;
159 struct x509_certificate *cert;
162 char *desc = NULL, *p;
165 cert = x509_cert_parse(prep->data, prep->datalen);
167 return PTR_ERR(cert);
169 pr_devel("Cert Issuer: %s\n", cert->issuer);
170 pr_devel("Cert Subject: %s\n", cert->subject);
172 if (cert->unsupported_key) {
174 goto error_free_cert;
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;
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;
231 /* We've finished with the certificate */
242 x509_free_certificate(cert);
246 static struct asymmetric_key_parser x509_key_parser = {
247 .owner = THIS_MODULE,
249 .parse = x509_key_preparse,
255 static int __init x509_key_init(void)
257 return register_asymmetric_key_parser(&x509_key_parser);
260 static void __exit x509_key_exit(void)
262 unregister_asymmetric_key_parser(&x509_key_parser);
265 module_init(x509_key_init);
266 module_exit(x509_key_exit);
268 MODULE_DESCRIPTION("X.509 certificate parser");
269 MODULE_AUTHOR("Red Hat, Inc.");
270 MODULE_LICENSE("GPL");