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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 DH |
81 | |
82 | ret = crypto_shash_init(desc); | |
83 | if (ret < 0) | |
77d0910d | 84 | goto error_2; |
b426beb6 | 85 | might_sleep(); |
77d0910d DH |
86 | ret = crypto_shash_finup(desc, cert->tbs, cert->tbs_size, sig->digest); |
87 | ||
88 | error_2: | |
89 | kfree(desc); | |
b426beb6 DH |
90 | error: |
91 | crypto_free_shash(tfm); | |
92 | pr_devel("<==%s() = %d\n", __func__, ret); | |
93 | return ret; | |
94 | } | |
c26fd69f | 95 | |
b426beb6 | 96 | /* |
6c2dc5ae DH |
97 | * Check for self-signedness in an X.509 cert and if found, check the signature |
98 | * immediately if we can. | |
b426beb6 | 99 | */ |
6c2dc5ae | 100 | int x509_check_for_self_signed(struct x509_certificate *cert) |
b426beb6 | 101 | { |
6c2dc5ae | 102 | int ret = 0; |
c26fd69f | 103 | |
b426beb6 | 104 | pr_devel("==>%s()\n", __func__); |
c26fd69f | 105 | |
ad3043fd DH |
106 | if (cert->raw_subject_size != cert->raw_issuer_size || |
107 | memcmp(cert->raw_subject, cert->raw_issuer, | |
108 | cert->raw_issuer_size) != 0) | |
109 | goto not_self_signed; | |
110 | ||
6c2dc5ae DH |
111 | if (cert->sig->auth_ids[0] || cert->sig->auth_ids[1]) { |
112 | /* If the AKID is present it may have one or two parts. If | |
113 | * both are supplied, both must match. | |
114 | */ | |
115 | bool a = asymmetric_key_id_same(cert->skid, cert->sig->auth_ids[1]); | |
116 | bool b = asymmetric_key_id_same(cert->id, cert->sig->auth_ids[0]); | |
117 | ||
118 | if (!a && !b) | |
119 | goto not_self_signed; | |
120 | ||
121 | ret = -EKEYREJECTED; | |
122 | if (((a && !b) || (b && !a)) && | |
123 | cert->sig->auth_ids[0] && cert->sig->auth_ids[1]) | |
124 | goto out; | |
125 | } | |
126 | ||
ad3043fd DH |
127 | ret = -EKEYREJECTED; |
128 | if (cert->pub->pkey_algo != cert->sig->pkey_algo) | |
129 | goto out; | |
130 | ||
6c2dc5ae DH |
131 | ret = public_key_verify_signature(cert->pub, cert->sig); |
132 | if (ret < 0) { | |
133 | if (ret == -ENOPKG) { | |
134 | cert->unsupported_sig = true; | |
135 | ret = 0; | |
136 | } | |
137 | goto out; | |
138 | } | |
139 | ||
140 | pr_devel("Cert Self-signature verified"); | |
141 | cert->self_signed = true; | |
c26fd69f | 142 | |
6c2dc5ae DH |
143 | out: |
144 | pr_devel("<==%s() = %d\n", __func__, ret); | |
c26fd69f | 145 | return ret; |
6c2dc5ae DH |
146 | |
147 | not_self_signed: | |
148 | pr_devel("<==%s() = 0 [not]\n", __func__); | |
149 | return 0; | |
c26fd69f DH |
150 | } |
151 | ||
152 | /* | |
153 | * Attempt to parse a data blob for a key as an X509 certificate. | |
154 | */ | |
155 | static int x509_key_preparse(struct key_preparsed_payload *prep) | |
156 | { | |
46963b77 | 157 | struct asymmetric_key_ids *kids; |
c26fd69f | 158 | struct x509_certificate *cert; |
46963b77 | 159 | const char *q; |
c26fd69f | 160 | size_t srlen, sulen; |
46963b77 | 161 | char *desc = NULL, *p; |
c26fd69f DH |
162 | int ret; |
163 | ||
164 | cert = x509_cert_parse(prep->data, prep->datalen); | |
165 | if (IS_ERR(cert)) | |
166 | return PTR_ERR(cert); | |
167 | ||
168 | pr_devel("Cert Issuer: %s\n", cert->issuer); | |
169 | pr_devel("Cert Subject: %s\n", cert->subject); | |
2ecdb23b | 170 | |
6c2dc5ae | 171 | if (cert->unsupported_key) { |
2ecdb23b DH |
172 | ret = -ENOPKG; |
173 | goto error_free_cert; | |
174 | } | |
175 | ||
4e8ae72a | 176 | pr_devel("Cert Key Algo: %s\n", cert->pub->pkey_algo); |
fd19a3d1 | 177 | pr_devel("Cert Valid period: %lld-%lld\n", cert->valid_from, cert->valid_to); |
c26fd69f | 178 | |
4e8ae72a | 179 | cert->pub->id_type = "X509"; |
c26fd69f | 180 | |
a511e1af | 181 | if (cert->unsupported_sig) { |
6c2dc5ae DH |
182 | public_key_signature_free(cert->sig); |
183 | cert->sig = NULL; | |
184 | } else { | |
185 | pr_devel("Cert Signature: %s + %s\n", | |
186 | cert->sig->pkey_algo, cert->sig->hash_algo); | |
c26fd69f DH |
187 | } |
188 | ||
189 | /* Propose a description */ | |
190 | sulen = strlen(cert->subject); | |
dd2f6c44 DH |
191 | if (cert->raw_skid) { |
192 | srlen = cert->raw_skid_size; | |
193 | q = cert->raw_skid; | |
194 | } else { | |
195 | srlen = cert->raw_serial_size; | |
196 | q = cert->raw_serial; | |
197 | } | |
46963b77 | 198 | |
c26fd69f | 199 | ret = -ENOMEM; |
46963b77 | 200 | desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL); |
c26fd69f DH |
201 | if (!desc) |
202 | goto error_free_cert; | |
46963b77 DH |
203 | p = memcpy(desc, cert->subject, sulen); |
204 | p += sulen; | |
205 | *p++ = ':'; | |
206 | *p++ = ' '; | |
207 | p = bin2hex(p, q, srlen); | |
208 | *p = 0; | |
209 | ||
210 | kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL); | |
211 | if (!kids) | |
212 | goto error_free_desc; | |
213 | kids->id[0] = cert->id; | |
214 | kids->id[1] = cert->skid; | |
c26fd69f DH |
215 | |
216 | /* We're pinning the module by being linked against it */ | |
217 | __module_get(public_key_subtype.owner); | |
146aa8b1 DH |
218 | prep->payload.data[asym_subtype] = &public_key_subtype; |
219 | prep->payload.data[asym_key_ids] = kids; | |
220 | prep->payload.data[asym_crypto] = cert->pub; | |
77d0910d | 221 | prep->payload.data[asym_auth] = cert->sig; |
c26fd69f DH |
222 | prep->description = desc; |
223 | prep->quotalen = 100; | |
224 | ||
225 | /* We've finished with the certificate */ | |
226 | cert->pub = NULL; | |
46963b77 DH |
227 | cert->id = NULL; |
228 | cert->skid = NULL; | |
77d0910d | 229 | cert->sig = NULL; |
c26fd69f DH |
230 | desc = NULL; |
231 | ret = 0; | |
232 | ||
46963b77 DH |
233 | error_free_desc: |
234 | kfree(desc); | |
c26fd69f DH |
235 | error_free_cert: |
236 | x509_free_certificate(cert); | |
237 | return ret; | |
238 | } | |
239 | ||
240 | static struct asymmetric_key_parser x509_key_parser = { | |
241 | .owner = THIS_MODULE, | |
242 | .name = "x509", | |
243 | .parse = x509_key_preparse, | |
244 | }; | |
245 | ||
246 | /* | |
247 | * Module stuff | |
248 | */ | |
249 | static int __init x509_key_init(void) | |
250 | { | |
251 | return register_asymmetric_key_parser(&x509_key_parser); | |
252 | } | |
253 | ||
254 | static void __exit x509_key_exit(void) | |
255 | { | |
256 | unregister_asymmetric_key_parser(&x509_key_parser); | |
257 | } | |
258 | ||
259 | module_init(x509_key_init); | |
260 | module_exit(x509_key_exit); | |
e19aaa7d KK |
261 | |
262 | MODULE_DESCRIPTION("X.509 certificate parser"); | |
263 | MODULE_LICENSE("GPL"); |