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 sig->data = cert->tbs;
34 sig->data_size = cert->tbs_size;
36 if (!cert->pub->pkey_algo)
37 cert->unsupported_key = true;
40 cert->unsupported_sig = true;
42 /* We check the hash if we can - even if we can't then verify it */
43 if (!sig->hash_algo) {
44 cert->unsupported_sig = true;
48 sig->s = kmemdup(cert->raw_sig, cert->raw_sig_size, GFP_KERNEL);
52 sig->s_size = cert->raw_sig_size;
54 /* Allocate the hashing algorithm we're going to need and find out how
55 * big the hash operational data will be.
57 tfm = crypto_alloc_shash(sig->hash_algo, 0, 0);
59 if (PTR_ERR(tfm) == -ENOENT) {
60 cert->unsupported_sig = true;
66 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
67 sig->digest_size = crypto_shash_digestsize(tfm);
70 sig->digest = kmalloc(sig->digest_size, GFP_KERNEL);
74 desc = kzalloc(desc_size, GFP_KERNEL);
80 ret = crypto_shash_digest(desc, cert->tbs, cert->tbs_size, sig->digest);
84 ret = is_hash_blacklisted(sig->digest, sig->digest_size, "tbs");
85 if (ret == -EKEYREJECTED) {
86 pr_err("Cert %*phN is blacklisted\n",
87 sig->digest_size, sig->digest);
88 cert->blacklisted = true;
95 crypto_free_shash(tfm);
96 pr_devel("<==%s() = %d\n", __func__, ret);
101 * Check for self-signedness in an X.509 cert and if found, check the signature
102 * immediately if we can.
104 int x509_check_for_self_signed(struct x509_certificate *cert)
108 pr_devel("==>%s()\n", __func__);
110 if (cert->raw_subject_size != cert->raw_issuer_size ||
111 memcmp(cert->raw_subject, cert->raw_issuer,
112 cert->raw_issuer_size) != 0)
113 goto not_self_signed;
115 if (cert->sig->auth_ids[0] || cert->sig->auth_ids[1]) {
116 /* If the AKID is present it may have one or two parts. If
117 * both are supplied, both must match.
119 bool a = asymmetric_key_id_same(cert->skid, cert->sig->auth_ids[1]);
120 bool b = asymmetric_key_id_same(cert->id, cert->sig->auth_ids[0]);
123 goto not_self_signed;
126 if (((a && !b) || (b && !a)) &&
127 cert->sig->auth_ids[0] && cert->sig->auth_ids[1])
132 if (strcmp(cert->pub->pkey_algo, cert->sig->pkey_algo) != 0 &&
133 (strncmp(cert->pub->pkey_algo, "ecdsa-", 6) != 0 ||
134 strcmp(cert->sig->pkey_algo, "ecdsa") != 0))
137 ret = public_key_verify_signature(cert->pub, cert->sig);
139 if (ret == -ENOPKG) {
140 cert->unsupported_sig = true;
146 pr_devel("Cert Self-signature verified");
147 cert->self_signed = true;
150 pr_devel("<==%s() = %d\n", __func__, ret);
154 pr_devel("<==%s() = 0 [not]\n", __func__);
159 * Attempt to parse a data blob for a key as an X509 certificate.
161 static int x509_key_preparse(struct key_preparsed_payload *prep)
163 struct asymmetric_key_ids *kids;
164 struct x509_certificate *cert;
167 char *desc = NULL, *p;
170 cert = x509_cert_parse(prep->data, prep->datalen);
172 return PTR_ERR(cert);
174 pr_devel("Cert Issuer: %s\n", cert->issuer);
175 pr_devel("Cert Subject: %s\n", cert->subject);
177 if (cert->unsupported_key) {
179 goto error_free_cert;
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);
185 cert->pub->id_type = "X509";
187 if (cert->unsupported_sig) {
188 public_key_signature_free(cert->sig);
191 pr_devel("Cert Signature: %s + %s\n",
192 cert->sig->pkey_algo, cert->sig->hash_algo);
195 /* Don't permit addition of blacklisted keys */
197 if (cert->blacklisted)
198 goto error_free_cert;
200 /* Propose a description */
201 sulen = strlen(cert->subject);
202 if (cert->raw_skid) {
203 srlen = cert->raw_skid_size;
206 srlen = cert->raw_serial_size;
207 q = cert->raw_serial;
211 desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL);
213 goto error_free_cert;
214 p = memcpy(desc, cert->subject, sulen);
218 p = bin2hex(p, q, srlen);
221 kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL);
223 goto error_free_desc;
224 kids->id[0] = cert->id;
225 kids->id[1] = cert->skid;
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;
236 /* We've finished with the certificate */
247 x509_free_certificate(cert);
251 static struct asymmetric_key_parser x509_key_parser = {
252 .owner = THIS_MODULE,
254 .parse = x509_key_preparse,
260 static int __init x509_key_init(void)
262 return register_asymmetric_key_parser(&x509_key_parser);
265 static void __exit x509_key_exit(void)
267 unregister_asymmetric_key_parser(&x509_key_parser);
270 module_init(x509_key_init);
271 module_exit(x509_key_exit);
273 MODULE_DESCRIPTION("X.509 certificate parser");
274 MODULE_AUTHOR("Red Hat, Inc.");
275 MODULE_LICENSE("GPL");