1 /* Instantiate a public key crypto key from an X.509 Certificate
3 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
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"
24 * Set up the signature parameters in an X.509 certificate. This involves
25 * digesting the signed data and extracting the signature.
27 int x509_get_sig_params(struct x509_certificate *cert)
29 struct public_key_signature *sig = cert->sig;
30 struct crypto_shash *tfm;
31 struct shash_desc *desc;
35 pr_devel("==>%s()\n", __func__);
37 if (!cert->pub->pkey_algo)
38 cert->unsupported_key = true;
41 cert->unsupported_sig = true;
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;
49 sig->s = kmemdup(cert->raw_sig, cert->raw_sig_size, GFP_KERNEL);
53 sig->s_size = cert->raw_sig_size;
55 /* Allocate the hashing algorithm we're going to need and find out how
56 * big the hash operational data will be.
58 tfm = crypto_alloc_shash(sig->hash_algo, 0, 0);
60 if (PTR_ERR(tfm) == -ENOENT) {
61 cert->unsupported_sig = true;
67 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
68 sig->digest_size = crypto_shash_digestsize(tfm);
71 sig->digest = kmalloc(sig->digest_size, GFP_KERNEL);
75 desc = kzalloc(desc_size, GFP_KERNEL);
80 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
82 ret = crypto_shash_init(desc);
86 ret = crypto_shash_finup(desc, cert->tbs, cert->tbs_size, sig->digest);
90 ret = is_hash_blacklisted(sig->digest, sig->digest_size, "tbs");
91 if (ret == -EKEYREJECTED) {
92 pr_err("Cert %*phN is blacklisted\n",
93 sig->digest_size, sig->digest);
94 cert->blacklisted = true;
101 crypto_free_shash(tfm);
102 pr_devel("<==%s() = %d\n", __func__, ret);
107 * Check for self-signedness in an X.509 cert and if found, check the signature
108 * immediately if we can.
110 int x509_check_for_self_signed(struct x509_certificate *cert)
114 pr_devel("==>%s()\n", __func__);
116 if (cert->raw_subject_size != cert->raw_issuer_size ||
117 memcmp(cert->raw_subject, cert->raw_issuer,
118 cert->raw_issuer_size) != 0)
119 goto not_self_signed;
121 if (cert->sig->auth_ids[0] || cert->sig->auth_ids[1]) {
122 /* If the AKID is present it may have one or two parts. If
123 * both are supplied, both must match.
125 bool a = asymmetric_key_id_same(cert->skid, cert->sig->auth_ids[1]);
126 bool b = asymmetric_key_id_same(cert->id, cert->sig->auth_ids[0]);
129 goto not_self_signed;
132 if (((a && !b) || (b && !a)) &&
133 cert->sig->auth_ids[0] && cert->sig->auth_ids[1])
138 if (cert->pub->pkey_algo != cert->sig->pkey_algo)
141 ret = public_key_verify_signature(cert->pub, cert->sig);
143 if (ret == -ENOPKG) {
144 cert->unsupported_sig = true;
150 pr_devel("Cert Self-signature verified");
151 cert->self_signed = true;
154 pr_devel("<==%s() = %d\n", __func__, ret);
158 pr_devel("<==%s() = 0 [not]\n", __func__);
163 * Attempt to parse a data blob for a key as an X509 certificate.
165 static int x509_key_preparse(struct key_preparsed_payload *prep)
167 struct asymmetric_key_ids *kids;
168 struct x509_certificate *cert;
171 char *desc = NULL, *p;
174 cert = x509_cert_parse(prep->data, prep->datalen);
176 return PTR_ERR(cert);
178 pr_devel("Cert Issuer: %s\n", cert->issuer);
179 pr_devel("Cert Subject: %s\n", cert->subject);
181 if (cert->unsupported_key) {
183 goto error_free_cert;
186 pr_devel("Cert Key Algo: %s\n", cert->pub->pkey_algo);
187 pr_devel("Cert Valid period: %lld-%lld\n", cert->valid_from, cert->valid_to);
189 cert->pub->id_type = "X509";
191 if (cert->unsupported_sig) {
192 public_key_signature_free(cert->sig);
195 pr_devel("Cert Signature: %s + %s\n",
196 cert->sig->pkey_algo, cert->sig->hash_algo);
199 /* Don't permit addition of blacklisted keys */
201 if (cert->blacklisted)
202 goto error_free_cert;
204 /* Propose a description */
205 sulen = strlen(cert->subject);
206 if (cert->raw_skid) {
207 srlen = cert->raw_skid_size;
210 srlen = cert->raw_serial_size;
211 q = cert->raw_serial;
215 desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL);
217 goto error_free_cert;
218 p = memcpy(desc, cert->subject, sulen);
222 p = bin2hex(p, q, srlen);
225 kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL);
227 goto error_free_desc;
228 kids->id[0] = cert->id;
229 kids->id[1] = cert->skid;
231 /* We're pinning the module by being linked against it */
232 __module_get(public_key_subtype.owner);
233 prep->payload.data[asym_subtype] = &public_key_subtype;
234 prep->payload.data[asym_key_ids] = kids;
235 prep->payload.data[asym_crypto] = cert->pub;
236 prep->payload.data[asym_auth] = cert->sig;
237 prep->description = desc;
238 prep->quotalen = 100;
240 /* We've finished with the certificate */
251 x509_free_certificate(cert);
255 static struct asymmetric_key_parser x509_key_parser = {
256 .owner = THIS_MODULE,
258 .parse = x509_key_preparse,
264 static int __init x509_key_init(void)
266 return register_asymmetric_key_parser(&x509_key_parser);
269 static void __exit x509_key_exit(void)
271 unregister_asymmetric_key_parser(&x509_key_parser);
274 module_init(x509_key_init);
275 module_exit(x509_key_exit);
277 MODULE_DESCRIPTION("X.509 certificate parser");
278 MODULE_LICENSE("GPL");