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 char *hash_algo;
130 };
131
pkcs7_free(void * s)132 static void pkcs7_free(void *s)
133 {
134 struct kmod_signature_info *si = s;
135 struct pkcs7_private *pvt = si->private;
136
137 PKCS7_free(pvt->pkcs7);
138 BN_free(pvt->sno);
139 free(pvt->key_id);
140 free(pvt->hash_algo);
141 free(pvt);
142 si->private = NULL;
143 }
144
x509_name_to_str(X509_NAME * name)145 static const char *x509_name_to_str(X509_NAME *name)
146 {
147 int i;
148 X509_NAME_ENTRY *e;
149 ASN1_STRING *d;
150 ASN1_OBJECT *o;
151 int nid = -1;
152 const char *str;
153
154 for (i = 0; i < X509_NAME_entry_count(name); i++) {
155 e = X509_NAME_get_entry(name, i);
156 o = X509_NAME_ENTRY_get_object(e);
157 nid = OBJ_obj2nid(o);
158 if (nid == NID_commonName)
159 break;
160 }
161 if (nid == -1)
162 return NULL;
163
164 d = X509_NAME_ENTRY_get_data(e);
165 str = (const char *)ASN1_STRING_get0_data(d);
166
167 return str;
168 }
169
fill_pkcs7(const char * mem,off_t size,const struct module_signature * modsig,size_t sig_len,struct kmod_signature_info * sig_info)170 static bool fill_pkcs7(const char *mem, off_t size,
171 const struct module_signature *modsig, size_t sig_len,
172 struct kmod_signature_info *sig_info)
173 {
174 const char *pkcs7_raw;
175 PKCS7 *pkcs7;
176 STACK_OF(PKCS7_SIGNER_INFO) *sis;
177 PKCS7_SIGNER_INFO *si;
178 PKCS7_ISSUER_AND_SERIAL *is;
179 X509_NAME *issuer;
180 ASN1_INTEGER *sno;
181 ASN1_OCTET_STRING *sig;
182 BIGNUM *sno_bn;
183 X509_ALGOR *dig_alg;
184 X509_ALGOR *sig_alg;
185 const ASN1_OBJECT *o;
186 BIO *in;
187 int len;
188 unsigned char *key_id_str;
189 struct pkcs7_private *pvt;
190 const char *issuer_str;
191 char *hash_algo;
192 int hash_algo_len;
193
194 size -= sig_len;
195 pkcs7_raw = mem + size;
196
197 in = BIO_new_mem_buf(pkcs7_raw, sig_len);
198
199 pkcs7 = d2i_PKCS7_bio(in, NULL);
200 if (pkcs7 == NULL) {
201 BIO_free(in);
202 return false;
203 }
204
205 BIO_free(in);
206
207 sis = PKCS7_get_signer_info(pkcs7);
208 if (sis == NULL)
209 goto err;
210
211 si = sk_PKCS7_SIGNER_INFO_value(sis, 0);
212 if (si == NULL)
213 goto err;
214
215 is = si->issuer_and_serial;
216 if (is == NULL)
217 goto err;
218 issuer = is->issuer;
219 sno = is->serial;
220
221 sig = si->enc_digest;
222 if (sig == NULL)
223 goto err;
224
225 PKCS7_SIGNER_INFO_get0_algs(si, NULL, &dig_alg, &sig_alg);
226
227 sig_info->sig = (const char *)ASN1_STRING_get0_data(sig);
228 sig_info->sig_len = ASN1_STRING_length(sig);
229
230 sno_bn = ASN1_INTEGER_to_BN(sno, NULL);
231 if (sno_bn == NULL)
232 goto err;
233
234 len = BN_num_bytes(sno_bn);
235 key_id_str = malloc(len);
236 if (key_id_str == NULL)
237 goto err2;
238 BN_bn2bin(sno_bn, key_id_str);
239
240 sig_info->key_id = (const char *)key_id_str;
241 sig_info->key_id_len = len;
242
243 issuer_str = x509_name_to_str(issuer);
244 if (issuer_str != NULL) {
245 sig_info->signer = issuer_str;
246 sig_info->signer_len = strlen(issuer_str);
247 }
248
249 X509_ALGOR_get0(&o, NULL, NULL, dig_alg);
250
251 // Use OBJ_obj2txt to calculate string length
252 hash_algo_len = OBJ_obj2txt(NULL, 0, o, 0);
253 if (hash_algo_len < 0)
254 goto err3;
255 hash_algo = malloc(hash_algo_len + 1);
256 if (hash_algo == NULL)
257 goto err3;
258 hash_algo_len = OBJ_obj2txt(hash_algo, hash_algo_len + 1, o, 0);
259 if (hash_algo_len < 0)
260 goto err4;
261
262 // Assign libcrypto hash algo string or number
263 sig_info->hash_algo = hash_algo;
264
265 sig_info->id_type = pkey_id_type[modsig->id_type];
266
267 pvt = malloc(sizeof(*pvt));
268 if (pvt == NULL)
269 goto err4;
270
271 pvt->pkcs7 = pkcs7;
272 pvt->key_id = key_id_str;
273 pvt->sno = sno_bn;
274 pvt->hash_algo = hash_algo;
275 sig_info->private = pvt;
276
277 sig_info->free = pkcs7_free;
278
279 return true;
280 err4:
281 free(hash_algo);
282 err3:
283 free(key_id_str);
284 err2:
285 BN_free(sno_bn);
286 err:
287 PKCS7_free(pkcs7);
288 return false;
289 }
290
291 #else /* ENABLE OPENSSL */
292
fill_pkcs7(const char * mem,off_t size,const struct module_signature * modsig,size_t sig_len,struct kmod_signature_info * sig_info)293 static bool fill_pkcs7(const char *mem, off_t size,
294 const struct module_signature *modsig, size_t sig_len,
295 struct kmod_signature_info *sig_info)
296 {
297 sig_info->hash_algo = "unknown";
298 sig_info->id_type = pkey_id_type[modsig->id_type];
299 return true;
300 }
301
302 #endif /* ENABLE OPENSSL */
303
304 #define SIG_MAGIC "~Module signature appended~\n"
305
306 /*
307 * A signed module has the following layout:
308 *
309 * [ module ]
310 * [ signer's name ]
311 * [ key identifier ]
312 * [ signature data ]
313 * [ struct module_signature ]
314 * [ SIG_MAGIC ]
315 */
316
kmod_module_signature_info(const struct kmod_file * file,struct kmod_signature_info * sig_info)317 bool kmod_module_signature_info(const struct kmod_file *file, struct kmod_signature_info *sig_info)
318 {
319 const char *mem;
320 off_t size;
321 const struct module_signature *modsig;
322 size_t sig_len;
323
324 size = kmod_file_get_size(file);
325 mem = kmod_file_get_contents(file);
326 if (size < (off_t)strlen(SIG_MAGIC))
327 return false;
328 size -= strlen(SIG_MAGIC);
329 if (memcmp(SIG_MAGIC, mem + size, strlen(SIG_MAGIC)) != 0)
330 return false;
331
332 if (size < (off_t)sizeof(struct module_signature))
333 return false;
334 size -= sizeof(struct module_signature);
335 modsig = (struct module_signature *)(mem + size);
336 if (modsig->algo >= PKEY_ALGO__LAST ||
337 modsig->hash >= PKEY_HASH__LAST ||
338 modsig->id_type >= PKEY_ID_TYPE__LAST)
339 return false;
340 sig_len = be32toh(get_unaligned(&modsig->sig_len));
341 if (sig_len == 0 ||
342 size < (int64_t)(modsig->signer_len + modsig->key_id_len + sig_len))
343 return false;
344
345 switch (modsig->id_type) {
346 case PKEY_ID_PKCS7:
347 return fill_pkcs7(mem, size, modsig, sig_len, sig_info);
348 default:
349 return fill_default(mem, size, modsig, sig_len, sig_info);
350 }
351 }
352
kmod_module_signature_info_free(struct kmod_signature_info * sig_info)353 void kmod_module_signature_info_free(struct kmod_signature_info *sig_info)
354 {
355 if (sig_info->free)
356 sig_info->free(sig_info);
357 }
358