1 /*
2 * libkmod - module signature display
3 *
4 * Copyright (C) 2013 Michal Marek, SUSE
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
18 */
19
20 #include <inttypes.h>
21 #ifdef ENABLE_OPENSSL
22 #include <openssl/pkcs7.h>
23 #include <openssl/ssl.h>
24 #endif
25 #include <stdio.h>
26 #include <stdlib.h>
27 #include <string.h>
28
29 #include <shared/missing.h>
30 #include <shared/util.h>
31
32 #include "libkmod-internal.h"
33
34 /* These types and tables were copied from the 3.7 kernel sources.
35 * As this is just description of the signature format, it should not be
36 * considered derived work (so libkmod can use the LGPL license).
37 */
38 enum pkey_algo {
39 PKEY_ALGO_DSA,
40 PKEY_ALGO_RSA,
41 PKEY_ALGO__LAST
42 };
43
44 static const char *const pkey_algo[PKEY_ALGO__LAST] = {
45 [PKEY_ALGO_DSA] = "DSA",
46 [PKEY_ALGO_RSA] = "RSA",
47 };
48
49 enum pkey_hash_algo {
50 PKEY_HASH_MD4,
51 PKEY_HASH_MD5,
52 PKEY_HASH_SHA1,
53 PKEY_HASH_RIPE_MD_160,
54 PKEY_HASH_SHA256,
55 PKEY_HASH_SHA384,
56 PKEY_HASH_SHA512,
57 PKEY_HASH_SHA224,
58 PKEY_HASH_SM3,
59 PKEY_HASH__LAST
60 };
61
62 const char *const pkey_hash_algo[PKEY_HASH__LAST] = {
63 [PKEY_HASH_MD4] = "md4",
64 [PKEY_HASH_MD5] = "md5",
65 [PKEY_HASH_SHA1] = "sha1",
66 [PKEY_HASH_RIPE_MD_160] = "rmd160",
67 [PKEY_HASH_SHA256] = "sha256",
68 [PKEY_HASH_SHA384] = "sha384",
69 [PKEY_HASH_SHA512] = "sha512",
70 [PKEY_HASH_SHA224] = "sha224",
71 [PKEY_HASH_SM3] = "sm3",
72 };
73
74 enum pkey_id_type {
75 PKEY_ID_PGP, /* OpenPGP generated key ID */
76 PKEY_ID_X509, /* X.509 arbitrary subjectKeyIdentifier */
77 PKEY_ID_PKCS7, /* Signature in PKCS#7 message */
78 PKEY_ID_TYPE__LAST
79 };
80
81 const char *const pkey_id_type[PKEY_ID_TYPE__LAST] = {
82 [PKEY_ID_PGP] = "PGP",
83 [PKEY_ID_X509] = "X509",
84 [PKEY_ID_PKCS7] = "PKCS#7",
85 };
86
87 /*
88 * Module signature information block.
89 */
90 struct module_signature {
91 uint8_t algo; /* Public-key crypto algorithm [enum pkey_algo] */
92 uint8_t hash; /* Digest algorithm [enum pkey_hash_algo] */
93 uint8_t id_type; /* Key identifier type [enum pkey_id_type] */
94 uint8_t signer_len; /* Length of signer's name */
95 uint8_t key_id_len; /* Length of key identifier */
96 uint8_t __pad[3];
97 uint32_t sig_len; /* Length of signature data (big endian) */
98 };
99
fill_default(const char * mem,off_t size,const struct module_signature * modsig,size_t sig_len,struct kmod_signature_info * sig_info)100 static bool fill_default(const char *mem, off_t size,
101 const struct module_signature *modsig, size_t sig_len,
102 struct kmod_signature_info *sig_info)
103 {
104 size -= sig_len;
105 sig_info->sig = mem + size;
106 sig_info->sig_len = sig_len;
107
108 size -= modsig->key_id_len;
109 sig_info->key_id = mem + size;
110 sig_info->key_id_len = modsig->key_id_len;
111
112 size -= modsig->signer_len;
113 sig_info->signer = mem + size;
114 sig_info->signer_len = modsig->signer_len;
115
116 sig_info->algo = pkey_algo[modsig->algo];
117 sig_info->hash_algo = pkey_hash_algo[modsig->hash];
118 sig_info->id_type = pkey_id_type[modsig->id_type];
119
120 return true;
121 }
122
123 #ifdef ENABLE_OPENSSL
124
125 struct pkcs7_private {
126 PKCS7 *pkcs7;
127 unsigned char *key_id;
128 BIGNUM *sno;
129 };
130
pkcs7_free(void * s)131 static void pkcs7_free(void *s)
132 {
133 struct kmod_signature_info *si = s;
134 struct pkcs7_private *pvt = si->private;
135
136 PKCS7_free(pvt->pkcs7);
137 BN_free(pvt->sno);
138 free(pvt->key_id);
139 free(pvt);
140 si->private = NULL;
141 }
142
obj_to_hash_algo(const ASN1_OBJECT * o)143 static int obj_to_hash_algo(const ASN1_OBJECT *o)
144 {
145 int nid;
146
147 nid = OBJ_obj2nid(o);
148 switch (nid) {
149 case NID_md4:
150 return PKEY_HASH_MD4;
151 case NID_md5:
152 return PKEY_HASH_MD5;
153 case NID_sha1:
154 return PKEY_HASH_SHA1;
155 case NID_ripemd160:
156 return PKEY_HASH_RIPE_MD_160;
157 case NID_sha256:
158 return PKEY_HASH_SHA256;
159 case NID_sha384:
160 return PKEY_HASH_SHA384;
161 case NID_sha512:
162 return PKEY_HASH_SHA512;
163 case NID_sha224:
164 return PKEY_HASH_SHA224;
165 # ifndef OPENSSL_NO_SM3
166 case NID_sm3:
167 return PKEY_HASH_SM3;
168 # endif
169 default:
170 return -1;
171 }
172 return -1;
173 }
174
x509_name_to_str(X509_NAME * name)175 static const char *x509_name_to_str(X509_NAME *name)
176 {
177 int i;
178 X509_NAME_ENTRY *e;
179 ASN1_STRING *d;
180 ASN1_OBJECT *o;
181 int nid = -1;
182 const char *str;
183
184 for (i = 0; i < X509_NAME_entry_count(name); i++) {
185 e = X509_NAME_get_entry(name, i);
186 o = X509_NAME_ENTRY_get_object(e);
187 nid = OBJ_obj2nid(o);
188 if (nid == NID_commonName)
189 break;
190 }
191 if (nid == -1)
192 return NULL;
193
194 d = X509_NAME_ENTRY_get_data(e);
195 str = (const char *)ASN1_STRING_get0_data(d);
196
197 return str;
198 }
199
fill_pkcs7(const char * mem,off_t size,const struct module_signature * modsig,size_t sig_len,struct kmod_signature_info * sig_info)200 static bool fill_pkcs7(const char *mem, off_t size,
201 const struct module_signature *modsig, size_t sig_len,
202 struct kmod_signature_info *sig_info)
203 {
204 const char *pkcs7_raw;
205 PKCS7 *pkcs7;
206 STACK_OF(PKCS7_SIGNER_INFO) *sis;
207 PKCS7_SIGNER_INFO *si;
208 PKCS7_ISSUER_AND_SERIAL *is;
209 X509_NAME *issuer;
210 ASN1_INTEGER *sno;
211 ASN1_OCTET_STRING *sig;
212 BIGNUM *sno_bn;
213 X509_ALGOR *dig_alg;
214 X509_ALGOR *sig_alg;
215 const ASN1_OBJECT *o;
216 BIO *in;
217 int len;
218 unsigned char *key_id_str;
219 struct pkcs7_private *pvt;
220 const char *issuer_str;
221
222 size -= sig_len;
223 pkcs7_raw = mem + size;
224
225 in = BIO_new_mem_buf(pkcs7_raw, sig_len);
226
227 pkcs7 = d2i_PKCS7_bio(in, NULL);
228 if (pkcs7 == NULL) {
229 BIO_free(in);
230 return false;
231 }
232
233 BIO_free(in);
234
235 sis = PKCS7_get_signer_info(pkcs7);
236 if (sis == NULL)
237 goto err;
238
239 si = sk_PKCS7_SIGNER_INFO_value(sis, 0);
240 if (si == NULL)
241 goto err;
242
243 is = si->issuer_and_serial;
244 if (is == NULL)
245 goto err;
246 issuer = is->issuer;
247 sno = is->serial;
248
249 sig = si->enc_digest;
250 if (sig == NULL)
251 goto err;
252
253 PKCS7_SIGNER_INFO_get0_algs(si, NULL, &dig_alg, &sig_alg);
254
255 sig_info->sig = (const char *)ASN1_STRING_get0_data(sig);
256 sig_info->sig_len = ASN1_STRING_length(sig);
257
258 sno_bn = ASN1_INTEGER_to_BN(sno, NULL);
259 if (sno_bn == NULL)
260 goto err;
261
262 len = BN_num_bytes(sno_bn);
263 key_id_str = malloc(len);
264 if (key_id_str == NULL)
265 goto err2;
266 BN_bn2bin(sno_bn, key_id_str);
267
268 sig_info->key_id = (const char *)key_id_str;
269 sig_info->key_id_len = len;
270
271 issuer_str = x509_name_to_str(issuer);
272 if (issuer_str != NULL) {
273 sig_info->signer = issuer_str;
274 sig_info->signer_len = strlen(issuer_str);
275 }
276
277 X509_ALGOR_get0(&o, NULL, NULL, dig_alg);
278
279 sig_info->hash_algo = pkey_hash_algo[obj_to_hash_algo(o)];
280 sig_info->id_type = pkey_id_type[modsig->id_type];
281
282 pvt = malloc(sizeof(*pvt));
283 if (pvt == NULL)
284 goto err3;
285
286 pvt->pkcs7 = pkcs7;
287 pvt->key_id = key_id_str;
288 pvt->sno = sno_bn;
289 sig_info->private = pvt;
290
291 sig_info->free = pkcs7_free;
292
293 return true;
294 err3:
295 free(key_id_str);
296 err2:
297 BN_free(sno_bn);
298 err:
299 PKCS7_free(pkcs7);
300 return false;
301 }
302
303 #else /* ENABLE OPENSSL */
304
fill_pkcs7(const char * mem,off_t size,const struct module_signature * modsig,size_t sig_len,struct kmod_signature_info * sig_info)305 static bool fill_pkcs7(const char *mem, off_t size,
306 const struct module_signature *modsig, size_t sig_len,
307 struct kmod_signature_info *sig_info)
308 {
309 sig_info->hash_algo = "unknown";
310 sig_info->id_type = pkey_id_type[modsig->id_type];
311 return true;
312 }
313
314 #endif /* ENABLE OPENSSL */
315
316 #define SIG_MAGIC "~Module signature appended~\n"
317
318 /*
319 * A signed module has the following layout:
320 *
321 * [ module ]
322 * [ signer's name ]
323 * [ key identifier ]
324 * [ signature data ]
325 * [ struct module_signature ]
326 * [ SIG_MAGIC ]
327 */
328
kmod_module_signature_info(const struct kmod_file * file,struct kmod_signature_info * sig_info)329 bool kmod_module_signature_info(const struct kmod_file *file, struct kmod_signature_info *sig_info)
330 {
331 const char *mem;
332 off_t size;
333 const struct module_signature *modsig;
334 size_t sig_len;
335
336 size = kmod_file_get_size(file);
337 mem = kmod_file_get_contents(file);
338 if (size < (off_t)strlen(SIG_MAGIC))
339 return false;
340 size -= strlen(SIG_MAGIC);
341 if (memcmp(SIG_MAGIC, mem + size, strlen(SIG_MAGIC)) != 0)
342 return false;
343
344 if (size < (off_t)sizeof(struct module_signature))
345 return false;
346 size -= sizeof(struct module_signature);
347 modsig = (struct module_signature *)(mem + size);
348 if (modsig->algo >= PKEY_ALGO__LAST ||
349 modsig->hash >= PKEY_HASH__LAST ||
350 modsig->id_type >= PKEY_ID_TYPE__LAST)
351 return false;
352 sig_len = be32toh(get_unaligned(&modsig->sig_len));
353 if (sig_len == 0 ||
354 size < (int64_t)(modsig->signer_len + modsig->key_id_len + sig_len))
355 return false;
356
357 switch (modsig->id_type) {
358 case PKEY_ID_PKCS7:
359 return fill_pkcs7(mem, size, modsig, sig_len, sig_info);
360 default:
361 return fill_default(mem, size, modsig, sig_len, sig_info);
362 }
363 }
364
kmod_module_signature_info_free(struct kmod_signature_info * sig_info)365 void kmod_module_signature_info_free(struct kmod_signature_info *sig_info)
366 {
367 if (sig_info->free)
368 sig_info->free(sig_info);
369 }
370