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c26fd69f DH |
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> | |
c26fd69f DH |
16 | #include <keys/asymmetric-subtype.h> |
17 | #include <keys/asymmetric-parser.h> | |
3be4beaf | 18 | #include <keys/system_keyring.h> |
c26fd69f DH |
19 | #include <crypto/hash.h> |
20 | #include "asymmetric_keys.h" | |
c26fd69f DH |
21 | #include "x509_parser.h" |
22 | ||
c26fd69f | 23 | /* |
b426beb6 DH |
24 | * Set up the signature parameters in an X.509 certificate. This involves |
25 | * digesting the signed data and extracting the signature. | |
c26fd69f | 26 | */ |
b426beb6 | 27 | int x509_get_sig_params(struct x509_certificate *cert) |
c26fd69f | 28 | { |
77d0910d | 29 | struct public_key_signature *sig = cert->sig; |
c26fd69f DH |
30 | struct crypto_shash *tfm; |
31 | struct shash_desc *desc; | |
77d0910d | 32 | size_t desc_size; |
c26fd69f DH |
33 | int ret; |
34 | ||
35 | pr_devel("==>%s()\n", __func__); | |
b426beb6 | 36 | |
6c2dc5ae DH |
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; | |
b426beb6 | 46 | return 0; |
6c2dc5ae | 47 | } |
b426beb6 | 48 | |
77d0910d DH |
49 | sig->s = kmemdup(cert->raw_sig, cert->raw_sig_size, GFP_KERNEL); |
50 | if (!sig->s) | |
b426beb6 | 51 | return -ENOMEM; |
db6c43bd | 52 | |
77d0910d | 53 | sig->s_size = cert->raw_sig_size; |
b426beb6 | 54 | |
c26fd69f DH |
55 | /* Allocate the hashing algorithm we're going to need and find out how |
56 | * big the hash operational data will be. | |
57 | */ | |
77d0910d | 58 | tfm = crypto_alloc_shash(sig->hash_algo, 0, 0); |
41559420 DH |
59 | if (IS_ERR(tfm)) { |
60 | if (PTR_ERR(tfm) == -ENOENT) { | |
6c2dc5ae DH |
61 | cert->unsupported_sig = true; |
62 | return 0; | |
41559420 DH |
63 | } |
64 | return PTR_ERR(tfm); | |
65 | } | |
c26fd69f DH |
66 | |
67 | desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); | |
77d0910d | 68 | sig->digest_size = crypto_shash_digestsize(tfm); |
c26fd69f | 69 | |
c26fd69f | 70 | ret = -ENOMEM; |
77d0910d DH |
71 | sig->digest = kmalloc(sig->digest_size, GFP_KERNEL); |
72 | if (!sig->digest) | |
b426beb6 | 73 | goto error; |
c26fd69f | 74 | |
77d0910d DH |
75 | desc = kzalloc(desc_size, GFP_KERNEL); |
76 | if (!desc) | |
77 | goto error; | |
c26fd69f | 78 | |
b426beb6 DH |
79 | desc->tfm = tfm; |
80 | desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; | |
c26fd69f | 81 | |
aa330036 | 82 | ret = crypto_shash_digest(desc, cert->tbs, cert->tbs_size, sig->digest); |
43652956 DH |
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 | } | |
77d0910d DH |
93 | |
94 | error_2: | |
95 | kfree(desc); | |
b426beb6 DH |
96 | error: |
97 | crypto_free_shash(tfm); | |
98 | pr_devel("<==%s() = %d\n", __func__, ret); | |
99 | return ret; | |
100 | } | |
c26fd69f | 101 | |
b426beb6 | 102 | /* |
6c2dc5ae DH |
103 | * Check for self-signedness in an X.509 cert and if found, check the signature |
104 | * immediately if we can. | |
b426beb6 | 105 | */ |
6c2dc5ae | 106 | int x509_check_for_self_signed(struct x509_certificate *cert) |
b426beb6 | 107 | { |
6c2dc5ae | 108 | int ret = 0; |
c26fd69f | 109 | |
b426beb6 | 110 | pr_devel("==>%s()\n", __func__); |
c26fd69f | 111 | |
ad3043fd DH |
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 | ||
6c2dc5ae DH |
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 | ||
ad3043fd | 133 | ret = -EKEYREJECTED; |
54c1fb39 | 134 | if (strcmp(cert->pub->pkey_algo, cert->sig->pkey_algo) != 0) |
ad3043fd DH |
135 | goto out; |
136 | ||
6c2dc5ae DH |
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; | |
c26fd69f | 148 | |
6c2dc5ae DH |
149 | out: |
150 | pr_devel("<==%s() = %d\n", __func__, ret); | |
c26fd69f | 151 | return ret; |
6c2dc5ae DH |
152 | |
153 | not_self_signed: | |
154 | pr_devel("<==%s() = 0 [not]\n", __func__); | |
155 | return 0; | |
c26fd69f DH |
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 | { | |
46963b77 | 163 | struct asymmetric_key_ids *kids; |
c26fd69f | 164 | struct x509_certificate *cert; |
46963b77 | 165 | const char *q; |
c26fd69f | 166 | size_t srlen, sulen; |
46963b77 | 167 | char *desc = NULL, *p; |
c26fd69f DH |
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); | |
2ecdb23b | 176 | |
6c2dc5ae | 177 | if (cert->unsupported_key) { |
2ecdb23b DH |
178 | ret = -ENOPKG; |
179 | goto error_free_cert; | |
180 | } | |
181 | ||
4e8ae72a | 182 | pr_devel("Cert Key Algo: %s\n", cert->pub->pkey_algo); |
fd19a3d1 | 183 | pr_devel("Cert Valid period: %lld-%lld\n", cert->valid_from, cert->valid_to); |
c26fd69f | 184 | |
4e8ae72a | 185 | cert->pub->id_type = "X509"; |
c26fd69f | 186 | |
a511e1af | 187 | if (cert->unsupported_sig) { |
6c2dc5ae DH |
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); | |
c26fd69f DH |
193 | } |
194 | ||
43652956 DH |
195 | /* Don't permit addition of blacklisted keys */ |
196 | ret = -EKEYREJECTED; | |
197 | if (cert->blacklisted) | |
198 | goto error_free_cert; | |
199 | ||
c26fd69f DH |
200 | /* Propose a description */ |
201 | sulen = strlen(cert->subject); | |
dd2f6c44 DH |
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 | } | |
46963b77 | 209 | |
c26fd69f | 210 | ret = -ENOMEM; |
46963b77 | 211 | desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL); |
c26fd69f DH |
212 | if (!desc) |
213 | goto error_free_cert; | |
46963b77 DH |
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; | |
c26fd69f DH |
226 | |
227 | /* We're pinning the module by being linked against it */ | |
228 | __module_get(public_key_subtype.owner); | |
146aa8b1 DH |
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; | |
77d0910d | 232 | prep->payload.data[asym_auth] = cert->sig; |
c26fd69f DH |
233 | prep->description = desc; |
234 | prep->quotalen = 100; | |
235 | ||
236 | /* We've finished with the certificate */ | |
237 | cert->pub = NULL; | |
46963b77 DH |
238 | cert->id = NULL; |
239 | cert->skid = NULL; | |
77d0910d | 240 | cert->sig = NULL; |
c26fd69f DH |
241 | desc = NULL; |
242 | ret = 0; | |
243 | ||
46963b77 DH |
244 | error_free_desc: |
245 | kfree(desc); | |
c26fd69f DH |
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); | |
e19aaa7d KK |
272 | |
273 | MODULE_DESCRIPTION("X.509 certificate parser"); | |
1e684d38 | 274 | MODULE_AUTHOR("Red Hat, Inc."); |
e19aaa7d | 275 | MODULE_LICENSE("GPL"); |