Commit | Line | Data |
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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 | } | |
864e7a81 | 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 | } | |
864e7a81 | 140 | |
4573b64a DH |
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 | { |
77d0910d | 156 | struct public_key_signature *sig = cert->sig; |
c26fd69f DH |
157 | struct crypto_shash *tfm; |
158 | struct shash_desc *desc; | |
77d0910d | 159 | size_t desc_size; |
c26fd69f DH |
160 | int ret; |
161 | ||
162 | pr_devel("==>%s()\n", __func__); | |
b426beb6 | 163 | |
6c2dc5ae DH |
164 | if (!cert->pub->pkey_algo) |
165 | cert->unsupported_key = true; | |
166 | ||
167 | if (!sig->pkey_algo) | |
168 | cert->unsupported_sig = true; | |
169 | ||
170 | /* We check the hash if we can - even if we can't then verify it */ | |
171 | if (!sig->hash_algo) { | |
172 | cert->unsupported_sig = true; | |
b426beb6 | 173 | return 0; |
6c2dc5ae | 174 | } |
b426beb6 | 175 | |
77d0910d DH |
176 | sig->s = kmemdup(cert->raw_sig, cert->raw_sig_size, GFP_KERNEL); |
177 | if (!sig->s) | |
b426beb6 | 178 | return -ENOMEM; |
db6c43bd | 179 | |
77d0910d | 180 | sig->s_size = cert->raw_sig_size; |
b426beb6 | 181 | |
c26fd69f DH |
182 | /* Allocate the hashing algorithm we're going to need and find out how |
183 | * big the hash operational data will be. | |
184 | */ | |
77d0910d | 185 | tfm = crypto_alloc_shash(sig->hash_algo, 0, 0); |
41559420 DH |
186 | if (IS_ERR(tfm)) { |
187 | if (PTR_ERR(tfm) == -ENOENT) { | |
6c2dc5ae DH |
188 | cert->unsupported_sig = true; |
189 | return 0; | |
41559420 DH |
190 | } |
191 | return PTR_ERR(tfm); | |
192 | } | |
c26fd69f DH |
193 | |
194 | desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); | |
77d0910d | 195 | sig->digest_size = crypto_shash_digestsize(tfm); |
c26fd69f | 196 | |
c26fd69f | 197 | ret = -ENOMEM; |
77d0910d DH |
198 | sig->digest = kmalloc(sig->digest_size, GFP_KERNEL); |
199 | if (!sig->digest) | |
b426beb6 | 200 | goto error; |
c26fd69f | 201 | |
77d0910d DH |
202 | desc = kzalloc(desc_size, GFP_KERNEL); |
203 | if (!desc) | |
204 | goto error; | |
c26fd69f | 205 | |
b426beb6 DH |
206 | desc->tfm = tfm; |
207 | desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; | |
c26fd69f DH |
208 | |
209 | ret = crypto_shash_init(desc); | |
210 | if (ret < 0) | |
77d0910d | 211 | goto error_2; |
b426beb6 | 212 | might_sleep(); |
77d0910d DH |
213 | ret = crypto_shash_finup(desc, cert->tbs, cert->tbs_size, sig->digest); |
214 | ||
215 | error_2: | |
216 | kfree(desc); | |
b426beb6 DH |
217 | error: |
218 | crypto_free_shash(tfm); | |
219 | pr_devel("<==%s() = %d\n", __func__, ret); | |
220 | return ret; | |
221 | } | |
c26fd69f | 222 | |
b426beb6 | 223 | /* |
6c2dc5ae DH |
224 | * Check for self-signedness in an X.509 cert and if found, check the signature |
225 | * immediately if we can. | |
b426beb6 | 226 | */ |
6c2dc5ae | 227 | int x509_check_for_self_signed(struct x509_certificate *cert) |
b426beb6 | 228 | { |
6c2dc5ae | 229 | int ret = 0; |
c26fd69f | 230 | |
b426beb6 | 231 | pr_devel("==>%s()\n", __func__); |
c26fd69f | 232 | |
6c2dc5ae DH |
233 | if (cert->sig->auth_ids[0] || cert->sig->auth_ids[1]) { |
234 | /* If the AKID is present it may have one or two parts. If | |
235 | * both are supplied, both must match. | |
236 | */ | |
237 | bool a = asymmetric_key_id_same(cert->skid, cert->sig->auth_ids[1]); | |
238 | bool b = asymmetric_key_id_same(cert->id, cert->sig->auth_ids[0]); | |
239 | ||
240 | if (!a && !b) | |
241 | goto not_self_signed; | |
242 | ||
243 | ret = -EKEYREJECTED; | |
244 | if (((a && !b) || (b && !a)) && | |
245 | cert->sig->auth_ids[0] && cert->sig->auth_ids[1]) | |
246 | goto out; | |
247 | } | |
248 | ||
249 | ret = public_key_verify_signature(cert->pub, cert->sig); | |
250 | if (ret < 0) { | |
251 | if (ret == -ENOPKG) { | |
252 | cert->unsupported_sig = true; | |
253 | ret = 0; | |
254 | } | |
255 | goto out; | |
256 | } | |
257 | ||
258 | pr_devel("Cert Self-signature verified"); | |
259 | cert->self_signed = true; | |
c26fd69f | 260 | |
6c2dc5ae DH |
261 | out: |
262 | pr_devel("<==%s() = %d\n", __func__, ret); | |
c26fd69f | 263 | return ret; |
6c2dc5ae DH |
264 | |
265 | not_self_signed: | |
266 | pr_devel("<==%s() = 0 [not]\n", __func__); | |
267 | return 0; | |
c26fd69f DH |
268 | } |
269 | ||
3be4beaf MZ |
270 | /* |
271 | * Check the new certificate against the ones in the trust keyring. If one of | |
272 | * those is the signing key and validates the new certificate, then mark the | |
273 | * new certificate as being trusted. | |
274 | * | |
275 | * Return 0 if the new certificate was successfully validated, 1 if we couldn't | |
276 | * find a matching parent certificate in the trusted list and an error if there | |
277 | * is a matching certificate but the signature check fails. | |
278 | */ | |
279 | static int x509_validate_trust(struct x509_certificate *cert, | |
280 | struct key *trust_keyring) | |
281 | { | |
77d0910d | 282 | struct public_key_signature *sig = cert->sig; |
3be4beaf MZ |
283 | struct key *key; |
284 | int ret = 1; | |
285 | ||
6c2dc5ae DH |
286 | if (!sig->auth_ids[0] && !sig->auth_ids[1]) |
287 | return 1; | |
288 | ||
3be4beaf MZ |
289 | if (!trust_keyring) |
290 | return -EOPNOTSUPP; | |
77d0910d | 291 | if (ca_keyid && !asymmetric_key_id_partial(sig->auth_ids[1], ca_keyid)) |
ffb70f61 | 292 | return -EPERM; |
6c2dc5ae DH |
293 | if (cert->unsupported_sig) |
294 | return -ENOPKG; | |
ffb70f61 | 295 | |
4573b64a | 296 | key = x509_request_asymmetric_key(trust_keyring, |
77d0910d | 297 | sig->auth_ids[0], sig->auth_ids[1], |
f1b731db | 298 | false); |
6c2dc5ae DH |
299 | if (IS_ERR(key)) |
300 | return PTR_ERR(key); | |
301 | ||
302 | if (!use_builtin_keys || | |
303 | test_bit(KEY_FLAG_BUILTIN, &key->flags)) { | |
304 | ret = public_key_verify_signature( | |
305 | key->payload.data[asym_crypto], cert->sig); | |
306 | if (ret == -ENOPKG) | |
307 | cert->unsupported_sig = true; | |
3be4beaf | 308 | } |
6c2dc5ae | 309 | key_put(key); |
3be4beaf MZ |
310 | return ret; |
311 | } | |
312 | ||
c26fd69f DH |
313 | /* |
314 | * Attempt to parse a data blob for a key as an X509 certificate. | |
315 | */ | |
316 | static int x509_key_preparse(struct key_preparsed_payload *prep) | |
317 | { | |
46963b77 | 318 | struct asymmetric_key_ids *kids; |
c26fd69f | 319 | struct x509_certificate *cert; |
46963b77 | 320 | const char *q; |
c26fd69f | 321 | size_t srlen, sulen; |
46963b77 | 322 | char *desc = NULL, *p; |
c26fd69f DH |
323 | int ret; |
324 | ||
325 | cert = x509_cert_parse(prep->data, prep->datalen); | |
326 | if (IS_ERR(cert)) | |
327 | return PTR_ERR(cert); | |
328 | ||
329 | pr_devel("Cert Issuer: %s\n", cert->issuer); | |
330 | pr_devel("Cert Subject: %s\n", cert->subject); | |
2ecdb23b | 331 | |
6c2dc5ae | 332 | if (cert->unsupported_key) { |
2ecdb23b DH |
333 | ret = -ENOPKG; |
334 | goto error_free_cert; | |
335 | } | |
336 | ||
4e8ae72a | 337 | pr_devel("Cert Key Algo: %s\n", cert->pub->pkey_algo); |
fd19a3d1 | 338 | pr_devel("Cert Valid period: %lld-%lld\n", cert->valid_from, cert->valid_to); |
c26fd69f | 339 | |
4e8ae72a | 340 | cert->pub->id_type = "X509"; |
c26fd69f | 341 | |
6c2dc5ae DH |
342 | /* See if we can derive the trustability of this certificate. |
343 | * | |
344 | * When it comes to self-signed certificates, we cannot evaluate | |
345 | * trustedness except by the fact that we obtained it from a trusted | |
346 | * location. So we just rely on x509_validate_trust() failing in this | |
347 | * case. | |
348 | * | |
349 | * Note that there's a possibility of a self-signed cert matching a | |
350 | * cert that we have (most likely a duplicate that we already trust) - | |
351 | * in which case it will be marked trusted. | |
352 | */ | |
353 | if (cert->unsupported_sig || cert->self_signed) { | |
354 | public_key_signature_free(cert->sig); | |
355 | cert->sig = NULL; | |
356 | } else { | |
357 | pr_devel("Cert Signature: %s + %s\n", | |
358 | cert->sig->pkey_algo, cert->sig->hash_algo); | |
359 | ||
3be4beaf | 360 | ret = x509_validate_trust(cert, get_system_trusted_keyring()); |
41c89b64 PM |
361 | if (ret) |
362 | ret = x509_validate_trust(cert, get_ima_mok_keyring()); | |
6c2dc5ae DH |
363 | if (ret == -EKEYREJECTED) |
364 | goto error_free_cert; | |
3be4beaf | 365 | if (!ret) |
6c2dc5ae | 366 | prep->trusted = true; |
c26fd69f DH |
367 | } |
368 | ||
369 | /* Propose a description */ | |
370 | sulen = strlen(cert->subject); | |
dd2f6c44 DH |
371 | if (cert->raw_skid) { |
372 | srlen = cert->raw_skid_size; | |
373 | q = cert->raw_skid; | |
374 | } else { | |
375 | srlen = cert->raw_serial_size; | |
376 | q = cert->raw_serial; | |
377 | } | |
46963b77 | 378 | |
c26fd69f | 379 | ret = -ENOMEM; |
46963b77 | 380 | desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL); |
c26fd69f DH |
381 | if (!desc) |
382 | goto error_free_cert; | |
46963b77 DH |
383 | p = memcpy(desc, cert->subject, sulen); |
384 | p += sulen; | |
385 | *p++ = ':'; | |
386 | *p++ = ' '; | |
387 | p = bin2hex(p, q, srlen); | |
388 | *p = 0; | |
389 | ||
390 | kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL); | |
391 | if (!kids) | |
392 | goto error_free_desc; | |
393 | kids->id[0] = cert->id; | |
394 | kids->id[1] = cert->skid; | |
c26fd69f DH |
395 | |
396 | /* We're pinning the module by being linked against it */ | |
397 | __module_get(public_key_subtype.owner); | |
146aa8b1 DH |
398 | prep->payload.data[asym_subtype] = &public_key_subtype; |
399 | prep->payload.data[asym_key_ids] = kids; | |
400 | prep->payload.data[asym_crypto] = cert->pub; | |
77d0910d | 401 | prep->payload.data[asym_auth] = cert->sig; |
c26fd69f DH |
402 | prep->description = desc; |
403 | prep->quotalen = 100; | |
404 | ||
405 | /* We've finished with the certificate */ | |
406 | cert->pub = NULL; | |
46963b77 DH |
407 | cert->id = NULL; |
408 | cert->skid = NULL; | |
77d0910d | 409 | cert->sig = NULL; |
c26fd69f DH |
410 | desc = NULL; |
411 | ret = 0; | |
412 | ||
46963b77 DH |
413 | error_free_desc: |
414 | kfree(desc); | |
c26fd69f DH |
415 | error_free_cert: |
416 | x509_free_certificate(cert); | |
417 | return ret; | |
418 | } | |
419 | ||
420 | static struct asymmetric_key_parser x509_key_parser = { | |
421 | .owner = THIS_MODULE, | |
422 | .name = "x509", | |
423 | .parse = x509_key_preparse, | |
424 | }; | |
425 | ||
426 | /* | |
427 | * Module stuff | |
428 | */ | |
429 | static int __init x509_key_init(void) | |
430 | { | |
431 | return register_asymmetric_key_parser(&x509_key_parser); | |
432 | } | |
433 | ||
434 | static void __exit x509_key_exit(void) | |
435 | { | |
436 | unregister_asymmetric_key_parser(&x509_key_parser); | |
437 | } | |
438 | ||
439 | module_init(x509_key_init); | |
440 | module_exit(x509_key_exit); | |
e19aaa7d KK |
441 | |
442 | MODULE_DESCRIPTION("X.509 certificate parser"); | |
443 | MODULE_LICENSE("GPL"); |