GNU Linux-libre 4.19.211-gnu1
[releases.git] / crypto / asymmetric_keys / x509_public_key.c
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  */
27 int 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
94 error_2:
95         kfree(desc);
96 error:
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  */
106 int 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
149 out:
150         pr_devel("<==%s() = %d\n", __func__, ret);
151         return ret;
152
153 not_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  */
161 static 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
244 error_free_desc:
245         kfree(desc);
246 error_free_cert:
247         x509_free_certificate(cert);
248         return ret;
249 }
250
251 static 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  */
260 static int __init x509_key_init(void)
261 {
262         return register_asymmetric_key_parser(&x509_key_parser);
263 }
264
265 static void __exit x509_key_exit(void)
266 {
267         unregister_asymmetric_key_parser(&x509_key_parser);
268 }
269
270 module_init(x509_key_init);
271 module_exit(x509_key_exit);
272
273 MODULE_DESCRIPTION("X.509 certificate parser");
274 MODULE_AUTHOR("Red Hat, Inc.");
275 MODULE_LICENSE("GPL");