aboutsummaryrefslogtreecommitdiff
path: root/scripts/sign-file.c
blob: 19ec468b1168f4bf209e333bc194088257716960 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
/* Sign a module file using the given key.
 *
 * Copyright © 2014-2016 Red Hat, Inc. All Rights Reserved.
 * Copyright © 2015      Intel Corporation.
 * Copyright © 2016      Hewlett Packard Enterprise Development LP
 *
 * Authors: David Howells <dhowells@redhat.com>
 *          David Woodhouse <dwmw2@infradead.org>
 *          Juerg Haefliger <juerg.haefliger@hpe.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1
 * of the licence, or (at your option) any later version.
 */
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <getopt.h>
#include <err.h>
#include <arpa/inet.h>
#include <openssl/opensslv.h>
#include <openssl/bio.h>
#include <openssl/evp.h>
#include <openssl/pem.h>
#include <openssl/err.h>
#include <openssl/engine.h>

/*
 * Use CMS if we have openssl-1.0.0 or newer available - otherwise we have to
 * assume that it's not available and its header file is missing and that we
 * should use PKCS#7 instead.  Switching to the older PKCS#7 format restricts
 * the options we have on specifying the X.509 certificate we want.
 *
 * Further, older versions of OpenSSL don't support manually adding signers to
 * the PKCS#7 message so have to accept that we get a certificate included in
 * the signature message.  Nor do such older versions of OpenSSL support
 * signing with anything other than SHA1 - so we're stuck with that if such is
 * the case.
 */
#if OPENSSL_VERSION_NUMBER < 0x10000000L || defined(OPENSSL_NO_CMS)
#define USE_PKCS7
#endif
#ifndef USE_PKCS7
#include <openssl/cms.h>
#else
#include <openssl/pkcs7.h>
#endif

struct module_signature {
	uint8_t		algo;		/* Public-key crypto algorithm [0] */
	uint8_t		hash;		/* Digest algorithm [0] */
	uint8_t		id_type;	/* Key identifier type [PKEY_ID_PKCS7] */
	uint8_t		signer_len;	/* Length of signer's name [0] */
	uint8_t		key_id_len;	/* Length of key identifier [0] */
	uint8_t		__pad[3];
	uint32_t	sig_len;	/* Length of signature data */
};

#define PKEY_ID_PKCS7 2

static char magic_number[] = "~Module signature appended~\n";

static __attribute__((noreturn))
void format(void)
{
	fprintf(stderr,
		"Usage: scripts/sign-file [-dp] <hash algo> <key> <x509> <module> [<dest>]\n");
	fprintf(stderr,
		"       scripts/sign-file -s <raw sig> <hash algo> <x509> <module> [<dest>]\n");
	exit(2);
}

static void display_openssl_errors(int l)
{
	const char *file;
	char buf[120];
	int e, line;

	if (ERR_peek_error() == 0)
		return;
	fprintf(stderr, "At main.c:%d:\n", l);

	while ((e = ERR_get_error_line(&file, &line))) {
		ERR_error_string(e, buf);
		fprintf(stderr, "- SSL %s: %s:%d\n", buf, file, line);
	}
}

static void drain_openssl_errors(void)
{
	const char *file;
	int line;

	if (ERR_peek_error() == 0)
		return;
	while (ERR_get_error_line(&file, &line)) {}
}

#define ERR(cond, fmt, ...)				\
	do {						\
		bool __cond = (cond);			\
		display_openssl_errors(__LINE__);	\
		if (__cond) {				\
			err(1, fmt, ## __VA_ARGS__);	\
		}					\
	} while(0)

static const char *key_pass;

static int pem_pw_cb(char *buf, int len, int w, void *v)
{
	int pwlen;

	if (!key_pass)
		return -1;

	pwlen = strlen(key_pass);
	if (pwlen >= len)
		return -1;

	strcpy(buf, key_pass);

	/* If it's wrong, don't keep trying it. */
	key_pass = NULL;

	return pwlen;
}

static EVP_PKEY *read_private_key(const char *private_key_name)
{
	EVP_PKEY *private_key;

	if (!strncmp(private_key_name, "pkcs11:", 7)) {
		ENGINE *e;

		ENGINE_load_builtin_engines();
		drain_openssl_errors();
		e = ENGINE_by_id("pkcs11");
		ERR(!e, "Load PKCS#11 ENGINE");
		if (ENGINE_init(e))
			drain_openssl_errors();
		else
			ERR(1, "ENGINE_init");
		if (key_pass)
			ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0),
			    "Set PKCS#11 PIN");
		private_key = ENGINE_load_private_key(e, private_key_name,
						      NULL, NULL);
		ERR(!private_key, "%s", private_key_name);
	} else {
		BIO *b;

		b = BIO_new_file(private_key_name, "rb");
		ERR(!b, "%s", private_key_name);
		private_key = PEM_read_bio_PrivateKey(b, NULL, pem_pw_cb,
						      NULL);
		ERR(!private_key, "%s", private_key_name);
		BIO_free(b);
	}

	return private_key;
}

static X509 *read_x509(const char *x509_name)
{
	unsigned char buf[2];
	X509 *x509;
	BIO *b;
	int n;

	b = BIO_new_file(x509_name, "rb");
	ERR(!b, "%s", x509_name);

	/* Look at the first two bytes of the file to determine the encoding */
	n = BIO_read(b, buf, 2);
	if (n != 2) {
		if (BIO_should_retry(b)) {
			fprintf(stderr, "%s: Read wanted retry\n", x509_name);
			exit(1);
		}
		if (n >= 0) {
			fprintf(stderr, "%s: Short read\n", x509_name);
			exit(1);
		}
		ERR(1, "%s", x509_name);
	}

	ERR(BIO_reset(b) != 0, "%s", x509_name);

	if (buf[0] == 0x30 && buf[1] >= 0x81 && buf[1] <= 0x84)
		/* Assume raw DER encoded X.509 */
		x509 = d2i_X509_bio(b, NULL);
	else
		/* Assume PEM encoded X.509 */
		x509 = PEM_read_bio_X509(b, NULL, NULL, NULL);

	BIO_free(b);
	ERR(!x509, "%s", x509_name);

	return x509;
}

int main(int argc, char **argv)
{
	struct module_signature sig_info = { .id_type = PKEY_ID_PKCS7 };
	char *hash_algo = NULL;
	char *private_key_name = NULL, *raw_sig_name = NULL;
	char *x509_name, *module_name, *dest_name;
	bool save_sig = false, replace_orig;
	bool sign_only = false;
	bool raw_sig = false;
	unsigned char buf[4096];
	unsigned long module_size, sig_size;
	unsigned int use_signed_attrs;
	const EVP_MD *digest_algo;
	EVP_PKEY *private_key;
#ifndef USE_PKCS7
	CMS_ContentInfo *cms = NULL;
	unsigned int use_keyid = 0;
#else
	PKCS7 *pkcs7 = NULL;
#endif
	X509 *x509;
	BIO *bd, *bm;
	int opt, n;
	OpenSSL_add_all_algorithms();
	ERR_load_crypto_strings();
	ERR_clear_error();

	key_pass = getenv("KBUILD_SIGN_PIN");

#ifndef USE_PKCS7
	use_signed_attrs = CMS_NOATTR;
#else
	use_signed_attrs = PKCS7_NOATTR;
#endif

	do {
		opt = getopt(argc, argv, "sdpk");
		switch (opt) {
		case 's': raw_sig = true; break;
		case 'p': save_sig = true; break;
		case 'd': sign_only = true; save_sig = true; break;
#ifndef USE_PKCS7
		case 'k': use_keyid = CMS_USE_KEYID; break;
#endif
		case -1: break;
		default: format();
		}
	} while (opt != -1);

	argc -= optind;
	argv += optind;
	if (argc < 4 || argc > 5)
		format();

	if (raw_sig) {
		raw_sig_name = argv[0];
		hash_algo = argv[1];
	} else {
		hash_algo = argv[0];
		private_key_name = argv[1];
	}
	x509_name = argv[2];
	module_name = argv[3];
	if (argc == 5 && strcmp(argv[3], argv[4]) != 0) {
		dest_name = argv[4];
		replace_orig = false;
	} else {
		ERR(asprintf(&dest_name, "%s.~signed~", module_name) < 0,
		    "asprintf");
		replace_orig = true;
	}

#ifdef USE_PKCS7
	if (strcmp(hash_algo, "sha1") != 0) {
		fprintf(stderr, "sign-file: %s only supports SHA1 signing\n",
			OPENSSL_VERSION_TEXT);
		exit(3);
	}
#endif

	/* Open the module file */
	bm = BIO_new_file(module_name, "rb");
	ERR(!bm, "%s", module_name);

	if (!raw_sig) {
		/* Read the private key and the X.509 cert the PKCS#7 message
		 * will point to.
		 */
		private_key = read_private_key(private_key_name);
		x509 = read_x509(x509_name);

		/* Digest the module data. */
		OpenSSL_add_all_digests();
		display_openssl_errors(__LINE__);
		digest_algo = EVP_get_digestbyname(hash_algo);
		ERR(!digest_algo, "EVP_get_digestbyname");

#ifndef USE_PKCS7
		/* Load the signature message from the digest buffer. */
		cms = CMS_sign(NULL, NULL, NULL, NULL,
			       CMS_NOCERTS | CMS_PARTIAL | CMS_BINARY |
			       CMS_DETACHED | CMS_STREAM);
		ERR(!cms, "CMS_sign");

		ERR(!CMS_add1_signer(cms, x509, private_key, digest_algo,
				     CMS_NOCERTS | CMS_BINARY |
				     CMS_NOSMIMECAP | use_keyid |
				     use_signed_attrs),
		    "CMS_add1_signer");
		ERR(CMS_final(cms, bm, NULL, CMS_NOCERTS | CMS_BINARY) < 0,
		    "CMS_final");

#else
		pkcs7 = PKCS7_sign(x509, private_key, NULL, bm,
				   PKCS7_NOCERTS | PKCS7_BINARY |
				   PKCS7_DETACHED | use_signed_attrs);
		ERR(!pkcs7, "PKCS7_sign");
#endif

		if (save_sig) {
			char *sig_file_name;
			BIO *b;

			ERR(asprintf(&sig_file_name, "%s.p7s", module_name) < 0,
			    "asprintf");
			b = BIO_new_file(sig_file_name, "wb");
			ERR(!b, "%s", sig_file_name);
#ifndef USE_PKCS7
			ERR(i2d_CMS_bio_stream(b, cms, NULL, 0) < 0,
			    "%s", sig_file_name);
#else
			ERR(i2d_PKCS7_bio(b, pkcs7) < 0,
			    "%s", sig_file_name);
#endif
			BIO_free(b);
		}

		if (sign_only) {
			BIO_free(bm);
			return 0;
		}
	}

	/* Open the destination file now so that we can shovel the module data
	 * across as we read it.
	 */
	bd = BIO_new_file(dest_name, "wb");
	ERR(!bd, "%s", dest_name);

	/* Append the marker and the PKCS#7 message to the destination file */
	ERR(BIO_reset(bm) < 0, "%s", module_name);
	while ((n = BIO_read(bm, buf, sizeof(buf))),
	       n > 0) {
		ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
	}
	BIO_free(bm);
	ERR(n < 0, "%s", module_name);
	module_size = BIO_number_written(bd);

	if (!raw_sig) {
#ifndef USE_PKCS7
		ERR(i2d_CMS_bio_stream(bd, cms, NULL, 0) < 0, "%s", dest_name);
#else
		ERR(i2d_PKCS7_bio(bd, pkcs7) < 0, "%s", dest_name);
#endif
	} else {
		BIO *b;

		/* Read the raw signature file and write the data to the
		 * destination file
		 */
		b = BIO_new_file(raw_sig_name, "rb");
		ERR(!b, "%s", raw_sig_name);
		while ((n = BIO_read(b, buf, sizeof(buf))), n > 0)
			ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
		BIO_free(b);
	}

	sig_size = BIO_number_written(bd) - module_size;
	sig_info.sig_len = htonl(sig_size);
	ERR(BIO_write(bd, &sig_info, sizeof(sig_info)) < 0, "%s", dest_name);
	ERR(BIO_write(bd, magic_number, sizeof(magic_number) - 1) < 0, "%s", dest_name);

	ERR(BIO_free(bd) < 0, "%s", dest_name);

	/* Finally, if we're signing in place, replace the original. */
	if (replace_orig)
		ERR(rename(dest_name, module_name) < 0, "%s", dest_name);

	return 0;
}