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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 | ||
32c4741c | 23 | static bool use_builtin_keys; |
46963b77 | 24 | static struct asymmetric_key_id *ca_keyid; |
ffb70f61 DK |
25 | |
26 | #ifndef MODULE | |
f2b3dee4 MZ |
27 | static struct { |
28 | struct asymmetric_key_id id; | |
29 | unsigned char data[10]; | |
30 | } cakey; | |
31 | ||
ffb70f61 DK |
32 | static int __init ca_keys_setup(char *str) |
33 | { | |
34 | if (!str) /* default system keyring */ | |
35 | return 1; | |
36 | ||
46963b77 | 37 | if (strncmp(str, "id:", 3) == 0) { |
f2b3dee4 MZ |
38 | struct asymmetric_key_id *p = &cakey.id; |
39 | size_t hexlen = (strlen(str) - 3) / 2; | |
40 | int ret; | |
41 | ||
42 | if (hexlen == 0 || hexlen > sizeof(cakey.data)) { | |
43 | pr_err("Missing or invalid ca_keys id\n"); | |
44 | return 1; | |
45 | } | |
46 | ||
47 | ret = __asymmetric_key_hex_to_key_id(str + 3, p, hexlen); | |
48 | if (ret < 0) | |
49 | pr_err("Unparsable ca_keys id hex string\n"); | |
50 | else | |
46963b77 DH |
51 | ca_keyid = p; /* owner key 'id:xxxxxx' */ |
52 | } else if (strcmp(str, "builtin") == 0) { | |
32c4741c | 53 | use_builtin_keys = true; |
46963b77 | 54 | } |
ffb70f61 DK |
55 | |
56 | return 1; | |
57 | } | |
58 | __setup("ca_keys=", ca_keys_setup); | |
59 | #endif | |
60 | ||
5ce43ad2 DH |
61 | /** |
62 | * x509_request_asymmetric_key - Request a key by X.509 certificate params. | |
63 | * @keyring: The keys to search. | |
4573b64a DH |
64 | * @id: The issuer & serialNumber to look for or NULL. |
65 | * @skid: The subjectKeyIdentifier to look for or NULL. | |
f1b731db | 66 | * @partial: Use partial match if true, exact if false. |
5ce43ad2 | 67 | * |
4573b64a DH |
68 | * Find a key in the given keyring by identifier. The preferred identifier is |
69 | * the issuer + serialNumber and the fallback identifier is the | |
70 | * subjectKeyIdentifier. If both are given, the lookup is by the former, but | |
71 | * the latter must also match. | |
3be4beaf | 72 | */ |
5ce43ad2 | 73 | struct key *x509_request_asymmetric_key(struct key *keyring, |
4573b64a DH |
74 | const struct asymmetric_key_id *id, |
75 | const struct asymmetric_key_id *skid, | |
f1b731db | 76 | bool partial) |
3be4beaf | 77 | { |
4573b64a DH |
78 | struct key *key; |
79 | key_ref_t ref; | |
80 | const char *lookup; | |
81 | char *req, *p; | |
82 | int len; | |
83 | ||
84 | if (id) { | |
85 | lookup = id->data; | |
86 | len = id->len; | |
87 | } else { | |
88 | lookup = skid->data; | |
89 | len = skid->len; | |
90 | } | |
91 | ||
46963b77 | 92 | /* Construct an identifier "id:<keyid>". */ |
4573b64a DH |
93 | p = req = kmalloc(2 + 1 + len * 2 + 1, GFP_KERNEL); |
94 | if (!req) | |
3be4beaf MZ |
95 | return ERR_PTR(-ENOMEM); |
96 | ||
f1b731db DK |
97 | if (partial) { |
98 | *p++ = 'i'; | |
99 | *p++ = 'd'; | |
100 | } else { | |
101 | *p++ = 'e'; | |
102 | *p++ = 'x'; | |
103 | } | |
46963b77 | 104 | *p++ = ':'; |
4573b64a | 105 | p = bin2hex(p, lookup, len); |
46963b77 | 106 | *p = 0; |
3be4beaf | 107 | |
4573b64a | 108 | pr_debug("Look up: \"%s\"\n", req); |
3be4beaf | 109 | |
4573b64a DH |
110 | ref = keyring_search(make_key_ref(keyring, 1), |
111 | &key_type_asymmetric, req); | |
112 | if (IS_ERR(ref)) | |
113 | pr_debug("Request for key '%s' err %ld\n", req, PTR_ERR(ref)); | |
114 | kfree(req); | |
3be4beaf | 115 | |
4573b64a DH |
116 | if (IS_ERR(ref)) { |
117 | switch (PTR_ERR(ref)) { | |
3be4beaf MZ |
118 | /* Hide some search errors */ |
119 | case -EACCES: | |
120 | case -ENOTDIR: | |
121 | case -EAGAIN: | |
122 | return ERR_PTR(-ENOKEY); | |
123 | default: | |
4573b64a DH |
124 | return ERR_CAST(ref); |
125 | } | |
126 | } | |
127 | ||
128 | key = key_ref_to_ptr(ref); | |
129 | if (id && skid) { | |
130 | const struct asymmetric_key_ids *kids = asymmetric_key_ids(key); | |
131 | if (!kids->id[1]) { | |
132 | pr_debug("issuer+serial match, but expected SKID missing\n"); | |
133 | goto reject; | |
134 | } | |
135 | if (!asymmetric_key_id_same(skid, kids->id[1])) { | |
136 | pr_debug("issuer+serial match, but SKID does not\n"); | |
137 | goto reject; | |
3be4beaf MZ |
138 | } |
139 | } | |
4573b64a DH |
140 | |
141 | pr_devel("<==%s() = 0 [%x]\n", __func__, key_serial(key)); | |
142 | return key; | |
3be4beaf | 143 | |
4573b64a DH |
144 | reject: |
145 | key_put(key); | |
146 | return ERR_PTR(-EKEYREJECTED); | |
3be4beaf | 147 | } |
cf5b50fd | 148 | EXPORT_SYMBOL_GPL(x509_request_asymmetric_key); |
3be4beaf | 149 | |
c26fd69f | 150 | /* |
b426beb6 DH |
151 | * Set up the signature parameters in an X.509 certificate. This involves |
152 | * digesting the signed data and extracting the signature. | |
c26fd69f | 153 | */ |
b426beb6 | 154 | int x509_get_sig_params(struct x509_certificate *cert) |
c26fd69f | 155 | { |
c26fd69f DH |
156 | struct crypto_shash *tfm; |
157 | struct shash_desc *desc; | |
158 | size_t digest_size, desc_size; | |
b426beb6 | 159 | void *digest; |
c26fd69f DH |
160 | int ret; |
161 | ||
162 | pr_devel("==>%s()\n", __func__); | |
b426beb6 | 163 | |
41559420 DH |
164 | if (cert->unsupported_crypto) |
165 | return -ENOPKG; | |
db6c43bd | 166 | if (cert->sig.s) |
b426beb6 DH |
167 | return 0; |
168 | ||
db6c43bd TS |
169 | cert->sig.s = kmemdup(cert->raw_sig, cert->raw_sig_size, |
170 | GFP_KERNEL); | |
171 | if (!cert->sig.s) | |
b426beb6 | 172 | return -ENOMEM; |
db6c43bd TS |
173 | |
174 | cert->sig.s_size = cert->raw_sig_size; | |
b426beb6 | 175 | |
c26fd69f DH |
176 | /* Allocate the hashing algorithm we're going to need and find out how |
177 | * big the hash operational data will be. | |
178 | */ | |
4e8ae72a | 179 | tfm = crypto_alloc_shash(cert->sig.hash_algo, 0, 0); |
41559420 DH |
180 | if (IS_ERR(tfm)) { |
181 | if (PTR_ERR(tfm) == -ENOENT) { | |
182 | cert->unsupported_crypto = true; | |
183 | return -ENOPKG; | |
184 | } | |
185 | return PTR_ERR(tfm); | |
186 | } | |
c26fd69f DH |
187 | |
188 | desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); | |
189 | digest_size = crypto_shash_digestsize(tfm); | |
190 | ||
b426beb6 DH |
191 | /* We allocate the hash operational data storage on the end of the |
192 | * digest storage space. | |
c26fd69f DH |
193 | */ |
194 | ret = -ENOMEM; | |
271817a3 SV |
195 | digest = kzalloc(ALIGN(digest_size, __alignof__(*desc)) + desc_size, |
196 | GFP_KERNEL); | |
b426beb6 DH |
197 | if (!digest) |
198 | goto error; | |
c26fd69f | 199 | |
b426beb6 DH |
200 | cert->sig.digest = digest; |
201 | cert->sig.digest_size = digest_size; | |
c26fd69f | 202 | |
271817a3 | 203 | desc = PTR_ALIGN(digest + digest_size, __alignof__(*desc)); |
b426beb6 DH |
204 | desc->tfm = tfm; |
205 | desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; | |
c26fd69f DH |
206 | |
207 | ret = crypto_shash_init(desc); | |
208 | if (ret < 0) | |
209 | goto error; | |
b426beb6 DH |
210 | might_sleep(); |
211 | ret = crypto_shash_finup(desc, cert->tbs, cert->tbs_size, digest); | |
212 | error: | |
213 | crypto_free_shash(tfm); | |
214 | pr_devel("<==%s() = %d\n", __func__, ret); | |
215 | return ret; | |
216 | } | |
217 | EXPORT_SYMBOL_GPL(x509_get_sig_params); | |
c26fd69f | 218 | |
b426beb6 DH |
219 | /* |
220 | * Check the signature on a certificate using the provided public key | |
221 | */ | |
222 | int x509_check_signature(const struct public_key *pub, | |
223 | struct x509_certificate *cert) | |
224 | { | |
225 | int ret; | |
c26fd69f | 226 | |
b426beb6 | 227 | pr_devel("==>%s()\n", __func__); |
c26fd69f | 228 | |
b426beb6 DH |
229 | ret = x509_get_sig_params(cert); |
230 | if (ret < 0) | |
231 | return ret; | |
c26fd69f | 232 | |
b426beb6 | 233 | ret = public_key_verify_signature(pub, &cert->sig); |
41559420 DH |
234 | if (ret == -ENOPKG) |
235 | cert->unsupported_crypto = true; | |
c26fd69f | 236 | pr_debug("Cert Verification: %d\n", ret); |
c26fd69f DH |
237 | return ret; |
238 | } | |
b426beb6 | 239 | EXPORT_SYMBOL_GPL(x509_check_signature); |
c26fd69f | 240 | |
3be4beaf MZ |
241 | /* |
242 | * Check the new certificate against the ones in the trust keyring. If one of | |
243 | * those is the signing key and validates the new certificate, then mark the | |
244 | * new certificate as being trusted. | |
245 | * | |
246 | * Return 0 if the new certificate was successfully validated, 1 if we couldn't | |
247 | * find a matching parent certificate in the trusted list and an error if there | |
248 | * is a matching certificate but the signature check fails. | |
249 | */ | |
250 | static int x509_validate_trust(struct x509_certificate *cert, | |
251 | struct key *trust_keyring) | |
252 | { | |
3be4beaf MZ |
253 | struct key *key; |
254 | int ret = 1; | |
255 | ||
256 | if (!trust_keyring) | |
257 | return -EOPNOTSUPP; | |
258 | ||
b92e6570 | 259 | if (ca_keyid && !asymmetric_key_id_partial(cert->akid_skid, ca_keyid)) |
ffb70f61 DK |
260 | return -EPERM; |
261 | ||
4573b64a DH |
262 | key = x509_request_asymmetric_key(trust_keyring, |
263 | cert->akid_id, cert->akid_skid, | |
f1b731db | 264 | false); |
3be4beaf | 265 | if (!IS_ERR(key)) { |
32c4741c DK |
266 | if (!use_builtin_keys |
267 | || test_bit(KEY_FLAG_BUILTIN, &key->flags)) | |
146aa8b1 DH |
268 | ret = x509_check_signature(key->payload.data[asym_crypto], |
269 | cert); | |
3be4beaf MZ |
270 | key_put(key); |
271 | } | |
272 | return ret; | |
273 | } | |
274 | ||
c26fd69f DH |
275 | /* |
276 | * Attempt to parse a data blob for a key as an X509 certificate. | |
277 | */ | |
278 | static int x509_key_preparse(struct key_preparsed_payload *prep) | |
279 | { | |
46963b77 | 280 | struct asymmetric_key_ids *kids; |
c26fd69f | 281 | struct x509_certificate *cert; |
46963b77 | 282 | const char *q; |
c26fd69f | 283 | size_t srlen, sulen; |
46963b77 | 284 | char *desc = NULL, *p; |
c26fd69f DH |
285 | int ret; |
286 | ||
287 | cert = x509_cert_parse(prep->data, prep->datalen); | |
288 | if (IS_ERR(cert)) | |
289 | return PTR_ERR(cert); | |
290 | ||
291 | pr_devel("Cert Issuer: %s\n", cert->issuer); | |
292 | pr_devel("Cert Subject: %s\n", cert->subject); | |
2ecdb23b | 293 | |
4e8ae72a DH |
294 | if (!cert->pub->pkey_algo || |
295 | !cert->sig.pkey_algo || | |
296 | !cert->sig.hash_algo) { | |
2ecdb23b DH |
297 | ret = -ENOPKG; |
298 | goto error_free_cert; | |
299 | } | |
300 | ||
4e8ae72a | 301 | pr_devel("Cert Key Algo: %s\n", cert->pub->pkey_algo); |
fd19a3d1 | 302 | pr_devel("Cert Valid period: %lld-%lld\n", cert->valid_from, cert->valid_to); |
c7c8bb23 | 303 | pr_devel("Cert Signature: %s + %s\n", |
4e8ae72a DH |
304 | cert->sig.pkey_algo, |
305 | cert->sig.hash_algo); | |
c26fd69f | 306 | |
4e8ae72a | 307 | cert->pub->id_type = "X509"; |
c26fd69f | 308 | |
17334cab | 309 | /* Check the signature on the key if it appears to be self-signed */ |
4573b64a DH |
310 | if ((!cert->akid_skid && !cert->akid_id) || |
311 | asymmetric_key_id_same(cert->skid, cert->akid_skid) || | |
312 | asymmetric_key_id_same(cert->id, cert->akid_id)) { | |
3be4beaf | 313 | ret = x509_check_signature(cert->pub, cert); /* self-signed */ |
c26fd69f DH |
314 | if (ret < 0) |
315 | goto error_free_cert; | |
3be4beaf MZ |
316 | } else if (!prep->trusted) { |
317 | ret = x509_validate_trust(cert, get_system_trusted_keyring()); | |
41c89b64 PM |
318 | if (ret) |
319 | ret = x509_validate_trust(cert, get_ima_mok_keyring()); | |
3be4beaf MZ |
320 | if (!ret) |
321 | prep->trusted = 1; | |
c26fd69f DH |
322 | } |
323 | ||
324 | /* Propose a description */ | |
325 | sulen = strlen(cert->subject); | |
dd2f6c44 DH |
326 | if (cert->raw_skid) { |
327 | srlen = cert->raw_skid_size; | |
328 | q = cert->raw_skid; | |
329 | } else { | |
330 | srlen = cert->raw_serial_size; | |
331 | q = cert->raw_serial; | |
332 | } | |
46963b77 | 333 | |
c26fd69f | 334 | ret = -ENOMEM; |
46963b77 | 335 | desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL); |
c26fd69f DH |
336 | if (!desc) |
337 | goto error_free_cert; | |
46963b77 DH |
338 | p = memcpy(desc, cert->subject, sulen); |
339 | p += sulen; | |
340 | *p++ = ':'; | |
341 | *p++ = ' '; | |
342 | p = bin2hex(p, q, srlen); | |
343 | *p = 0; | |
344 | ||
345 | kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL); | |
346 | if (!kids) | |
347 | goto error_free_desc; | |
348 | kids->id[0] = cert->id; | |
349 | kids->id[1] = cert->skid; | |
c26fd69f DH |
350 | |
351 | /* We're pinning the module by being linked against it */ | |
352 | __module_get(public_key_subtype.owner); | |
146aa8b1 DH |
353 | prep->payload.data[asym_subtype] = &public_key_subtype; |
354 | prep->payload.data[asym_key_ids] = kids; | |
355 | prep->payload.data[asym_crypto] = cert->pub; | |
c26fd69f DH |
356 | prep->description = desc; |
357 | prep->quotalen = 100; | |
358 | ||
359 | /* We've finished with the certificate */ | |
360 | cert->pub = NULL; | |
46963b77 DH |
361 | cert->id = NULL; |
362 | cert->skid = NULL; | |
c26fd69f DH |
363 | desc = NULL; |
364 | ret = 0; | |
365 | ||
46963b77 DH |
366 | error_free_desc: |
367 | kfree(desc); | |
c26fd69f DH |
368 | error_free_cert: |
369 | x509_free_certificate(cert); | |
370 | return ret; | |
371 | } | |
372 | ||
373 | static struct asymmetric_key_parser x509_key_parser = { | |
374 | .owner = THIS_MODULE, | |
375 | .name = "x509", | |
376 | .parse = x509_key_preparse, | |
377 | }; | |
378 | ||
379 | /* | |
380 | * Module stuff | |
381 | */ | |
382 | static int __init x509_key_init(void) | |
383 | { | |
384 | return register_asymmetric_key_parser(&x509_key_parser); | |
385 | } | |
386 | ||
387 | static void __exit x509_key_exit(void) | |
388 | { | |
389 | unregister_asymmetric_key_parser(&x509_key_parser); | |
390 | } | |
391 | ||
392 | module_init(x509_key_init); | |
393 | module_exit(x509_key_exit); | |
e19aaa7d KK |
394 | |
395 | MODULE_DESCRIPTION("X.509 certificate parser"); | |
396 | MODULE_LICENSE("GPL"); |