1 /* Sign a module file using the given key.
2 *
3 * Copyright © 2014-2015 Red Hat, Inc. All Rights Reserved.
4 * Copyright © 2015 Intel Corporation.
5 *
6 * Authors: David Howells <dhowells@redhat.com>
7 * David Woodhouse <dwmw2@infradead.org>
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public License
11 * as published by the Free Software Foundation; either version 2.1
12 * of the licence, or (at your option) any later version.
13 */
14 #define _GNU_SOURCE
15 #include <stdio.h>
16 #include <stdlib.h>
17 #include <stdint.h>
18 #include <stdbool.h>
19 #include <string.h>
20 #include <getopt.h>
21 #include <err.h>
22 #include <arpa/inet.h>
23 #include <openssl/opensslv.h>
24 #include <openssl/bio.h>
25 #include <openssl/evp.h>
26 #include <openssl/pem.h>
27 #include <openssl/err.h>
28 #include <openssl/engine.h>
29
30 /*
31 * Use CMS if we have openssl-1.0.0 or newer available - otherwise we have to
32 * assume that it's not available and its header file is missing and that we
33 * should use PKCS#7 instead. Switching to the older PKCS#7 format restricts
34 * the options we have on specifying the X.509 certificate we want.
35 *
36 * Further, older versions of OpenSSL don't support manually adding signers to
37 * the PKCS#7 message so have to accept that we get a certificate included in
38 * the signature message. Nor do such older versions of OpenSSL support
39 * signing with anything other than SHA1 - so we're stuck with that if such is
40 * the case.
41 */
42 #if OPENSSL_VERSION_NUMBER < 0x10000000L
43 #define USE_PKCS7
44 #endif
45 #ifndef USE_PKCS7
46 #include <openssl/cms.h>
47 #else
48 #include <openssl/pkcs7.h>
49 #endif
50
51 struct module_signature {
52 uint8_t algo; /* Public-key crypto algorithm [0] */
53 uint8_t hash; /* Digest algorithm [0] */
54 uint8_t id_type; /* Key identifier type [PKEY_ID_PKCS7] */
55 uint8_t signer_len; /* Length of signer's name [0] */
56 uint8_t key_id_len; /* Length of key identifier [0] */
57 uint8_t __pad[3];
58 uint32_t sig_len; /* Length of signature data */
59 };
60
61 #define PKEY_ID_PKCS7 2
62
63 static char magic_number[] = "~Module signature appended~\n";
64
65 static __attribute__((noreturn))
format(void)66 void format(void)
67 {
68 fprintf(stderr,
69 "Usage: scripts/sign-file [-dp] <hash algo> <key> <x509> <module> [<dest>]\n");
70 exit(2);
71 }
72
display_openssl_errors(int l)73 static void display_openssl_errors(int l)
74 {
75 const char *file;
76 char buf[120];
77 int e, line;
78
79 if (ERR_peek_error() == 0)
80 return;
81 fprintf(stderr, "At main.c:%d:\n", l);
82
83 while ((e = ERR_get_error_line(&file, &line))) {
84 ERR_error_string(e, buf);
85 fprintf(stderr, "- SSL %s: %s:%d\n", buf, file, line);
86 }
87 }
88
drain_openssl_errors(void)89 static void drain_openssl_errors(void)
90 {
91 const char *file;
92 int line;
93
94 if (ERR_peek_error() == 0)
95 return;
96 while (ERR_get_error_line(&file, &line)) {}
97 }
98
99 #define ERR(cond, fmt, ...) \
100 do { \
101 bool __cond = (cond); \
102 display_openssl_errors(__LINE__); \
103 if (__cond) { \
104 err(1, fmt, ## __VA_ARGS__); \
105 } \
106 } while(0)
107
108 static const char *key_pass;
109
pem_pw_cb(char * buf,int len,int w,void * v)110 static int pem_pw_cb(char *buf, int len, int w, void *v)
111 {
112 int pwlen;
113
114 if (!key_pass)
115 return -1;
116
117 pwlen = strlen(key_pass);
118 if (pwlen >= len)
119 return -1;
120
121 strcpy(buf, key_pass);
122
123 /* If it's wrong, don't keep trying it. */
124 key_pass = NULL;
125
126 return pwlen;
127 }
128
main(int argc,char ** argv)129 int main(int argc, char **argv)
130 {
131 struct module_signature sig_info = { .id_type = PKEY_ID_PKCS7 };
132 char *hash_algo = NULL;
133 char *private_key_name, *x509_name, *module_name, *dest_name;
134 bool save_sig = false, replace_orig;
135 bool sign_only = false;
136 unsigned char buf[4096];
137 unsigned long module_size, sig_size;
138 unsigned int use_signed_attrs;
139 const EVP_MD *digest_algo;
140 EVP_PKEY *private_key;
141 #ifndef USE_PKCS7
142 CMS_ContentInfo *cms;
143 unsigned int use_keyid = 0;
144 #else
145 PKCS7 *pkcs7;
146 #endif
147 X509 *x509;
148 BIO *b, *bd = NULL, *bm;
149 int opt, n;
150 OpenSSL_add_all_algorithms();
151 ERR_load_crypto_strings();
152 ERR_clear_error();
153
154 key_pass = getenv("KBUILD_SIGN_PIN");
155
156 #ifndef USE_PKCS7
157 use_signed_attrs = CMS_NOATTR;
158 #else
159 use_signed_attrs = PKCS7_NOATTR;
160 #endif
161
162 do {
163 opt = getopt(argc, argv, "dpk");
164 switch (opt) {
165 case 'p': save_sig = true; break;
166 case 'd': sign_only = true; save_sig = true; break;
167 #ifndef USE_PKCS7
168 case 'k': use_keyid = CMS_USE_KEYID; break;
169 #endif
170 case -1: break;
171 default: format();
172 }
173 } while (opt != -1);
174
175 argc -= optind;
176 argv += optind;
177 if (argc < 4 || argc > 5)
178 format();
179
180 hash_algo = argv[0];
181 private_key_name = argv[1];
182 x509_name = argv[2];
183 module_name = argv[3];
184 if (argc == 5) {
185 dest_name = argv[4];
186 replace_orig = false;
187 } else {
188 ERR(asprintf(&dest_name, "%s.~signed~", module_name) < 0,
189 "asprintf");
190 replace_orig = true;
191 }
192
193 #ifdef USE_PKCS7
194 if (strcmp(hash_algo, "sha1") != 0) {
195 fprintf(stderr, "sign-file: %s only supports SHA1 signing\n",
196 OPENSSL_VERSION_TEXT);
197 exit(3);
198 }
199 #endif
200
201 /* Read the private key and the X.509 cert the PKCS#7 message
202 * will point to.
203 */
204 if (!strncmp(private_key_name, "pkcs11:", 7)) {
205 ENGINE *e;
206
207 ENGINE_load_builtin_engines();
208 drain_openssl_errors();
209 e = ENGINE_by_id("pkcs11");
210 ERR(!e, "Load PKCS#11 ENGINE");
211 if (ENGINE_init(e))
212 drain_openssl_errors();
213 else
214 ERR(1, "ENGINE_init");
215 if (key_pass)
216 ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0), "Set PKCS#11 PIN");
217 private_key = ENGINE_load_private_key(e, private_key_name, NULL,
218 NULL);
219 ERR(!private_key, "%s", private_key_name);
220 } else {
221 b = BIO_new_file(private_key_name, "rb");
222 ERR(!b, "%s", private_key_name);
223 private_key = PEM_read_bio_PrivateKey(b, NULL, pem_pw_cb, NULL);
224 ERR(!private_key, "%s", private_key_name);
225 BIO_free(b);
226 }
227
228 b = BIO_new_file(x509_name, "rb");
229 ERR(!b, "%s", x509_name);
230 x509 = d2i_X509_bio(b, NULL); /* Binary encoded X.509 */
231 if (!x509) {
232 ERR(BIO_reset(b) != 1, "%s", x509_name);
233 x509 = PEM_read_bio_X509(b, NULL, NULL, NULL); /* PEM encoded X.509 */
234 if (x509)
235 drain_openssl_errors();
236 }
237 BIO_free(b);
238 ERR(!x509, "%s", x509_name);
239
240 /* Open the destination file now so that we can shovel the module data
241 * across as we read it.
242 */
243 if (!sign_only) {
244 bd = BIO_new_file(dest_name, "wb");
245 ERR(!bd, "%s", dest_name);
246 }
247
248 /* Digest the module data. */
249 OpenSSL_add_all_digests();
250 display_openssl_errors(__LINE__);
251 digest_algo = EVP_get_digestbyname(hash_algo);
252 ERR(!digest_algo, "EVP_get_digestbyname");
253
254 bm = BIO_new_file(module_name, "rb");
255 ERR(!bm, "%s", module_name);
256
257 #ifndef USE_PKCS7
258 /* Load the signature message from the digest buffer. */
259 cms = CMS_sign(NULL, NULL, NULL, NULL,
260 CMS_NOCERTS | CMS_PARTIAL | CMS_BINARY | CMS_DETACHED | CMS_STREAM);
261 ERR(!cms, "CMS_sign");
262
263 ERR(!CMS_add1_signer(cms, x509, private_key, digest_algo,
264 CMS_NOCERTS | CMS_BINARY | CMS_NOSMIMECAP |
265 use_keyid | use_signed_attrs),
266 "CMS_add1_signer");
267 ERR(CMS_final(cms, bm, NULL, CMS_NOCERTS | CMS_BINARY) < 0,
268 "CMS_final");
269
270 #else
271 pkcs7 = PKCS7_sign(x509, private_key, NULL, bm,
272 PKCS7_NOCERTS | PKCS7_BINARY |
273 PKCS7_DETACHED | use_signed_attrs);
274 ERR(!pkcs7, "PKCS7_sign");
275 #endif
276
277 if (save_sig) {
278 char *sig_file_name;
279
280 ERR(asprintf(&sig_file_name, "%s.p7s", module_name) < 0,
281 "asprintf");
282 b = BIO_new_file(sig_file_name, "wb");
283 ERR(!b, "%s", sig_file_name);
284 #ifndef USE_PKCS7
285 ERR(i2d_CMS_bio_stream(b, cms, NULL, 0) < 0,
286 "%s", sig_file_name);
287 #else
288 ERR(i2d_PKCS7_bio(b, pkcs7) < 0,
289 "%s", sig_file_name);
290 #endif
291 BIO_free(b);
292 }
293
294 if (sign_only)
295 return 0;
296
297 /* Append the marker and the PKCS#7 message to the destination file */
298 ERR(BIO_reset(bm) < 0, "%s", module_name);
299 while ((n = BIO_read(bm, buf, sizeof(buf))),
300 n > 0) {
301 ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
302 }
303 ERR(n < 0, "%s", module_name);
304 module_size = BIO_number_written(bd);
305
306 #ifndef USE_PKCS7
307 ERR(i2d_CMS_bio_stream(bd, cms, NULL, 0) < 0, "%s", dest_name);
308 #else
309 ERR(i2d_PKCS7_bio(bd, pkcs7) < 0, "%s", dest_name);
310 #endif
311 sig_size = BIO_number_written(bd) - module_size;
312 sig_info.sig_len = htonl(sig_size);
313 ERR(BIO_write(bd, &sig_info, sizeof(sig_info)) < 0, "%s", dest_name);
314 ERR(BIO_write(bd, magic_number, sizeof(magic_number) - 1) < 0, "%s", dest_name);
315
316 ERR(BIO_free(bd) < 0, "%s", dest_name);
317
318 /* Finally, if we're signing in place, replace the original. */
319 if (replace_orig)
320 ERR(rename(dest_name, module_name) < 0, "%s", dest_name);
321
322 return 0;
323 }
324