1 /* Sign a module file using the given key.
2  *
3  * Copyright © 2014-2016 Red Hat, Inc. All Rights Reserved.
4  * Copyright © 2015      Intel Corporation.
5  * Copyright © 2016      Hewlett Packard Enterprise Development LP
6  *
7  * Authors: David Howells <dhowells@redhat.com>
8  *          David Woodhouse <dwmw2@infradead.org>
9  *          Juerg Haefliger <juerg.haefliger@hpe.com>
10  *
11  * This program is free software; you can redistribute it and/or
12  * modify it under the terms of the GNU Lesser General Public License
13  * as published by the Free Software Foundation; either version 2.1
14  * of the licence, or (at your option) any later version.
15  */
16 #define _GNU_SOURCE
17 #include <stdio.h>
18 #include <stdlib.h>
19 #include <stdint.h>
20 #include <stdbool.h>
21 #include <string.h>
22 #include <getopt.h>
23 #include <err.h>
24 #include <arpa/inet.h>
25 #include <openssl/opensslv.h>
26 #include <openssl/bio.h>
27 #include <openssl/evp.h>
28 #include <openssl/pem.h>
29 #include <openssl/err.h>
30 #include <openssl/engine.h>
31 
32 /*
33  * Use CMS if we have openssl-1.0.0 or newer available - otherwise we have to
34  * assume that it's not available and its header file is missing and that we
35  * should use PKCS#7 instead.  Switching to the older PKCS#7 format restricts
36  * the options we have on specifying the X.509 certificate we want.
37  *
38  * Further, older versions of OpenSSL don't support manually adding signers to
39  * the PKCS#7 message so have to accept that we get a certificate included in
40  * the signature message.  Nor do such older versions of OpenSSL support
41  * signing with anything other than SHA1 - so we're stuck with that if such is
42  * the case.
43  */
44 #if defined(LIBRESSL_VERSION_NUMBER) || \
45 	OPENSSL_VERSION_NUMBER < 0x10000000L || \
46 	defined(OPENSSL_NO_CMS)
47 #define USE_PKCS7
48 #endif
49 #ifndef USE_PKCS7
50 #include <openssl/cms.h>
51 #else
52 #include <openssl/pkcs7.h>
53 #endif
54 
55 struct module_signature {
56 	uint8_t		algo;		/* Public-key crypto algorithm [0] */
57 	uint8_t		hash;		/* Digest algorithm [0] */
58 	uint8_t		id_type;	/* Key identifier type [PKEY_ID_PKCS7] */
59 	uint8_t		signer_len;	/* Length of signer's name [0] */
60 	uint8_t		key_id_len;	/* Length of key identifier [0] */
61 	uint8_t		__pad[3];
62 	uint32_t	sig_len;	/* Length of signature data */
63 };
64 
65 #define PKEY_ID_PKCS7 2
66 
67 static char magic_number[] = "~Module signature appended~\n";
68 
69 static __attribute__((noreturn))
format(void)70 void format(void)
71 {
72 	fprintf(stderr,
73 		"Usage: scripts/sign-file [-dp] <hash algo> <key> <x509> <module> [<dest>]\n");
74 	fprintf(stderr,
75 		"       scripts/sign-file -s <raw sig> <hash algo> <x509> <module> [<dest>]\n");
76 	exit(2);
77 }
78 
display_openssl_errors(int l)79 static void display_openssl_errors(int l)
80 {
81 	const char *file;
82 	char buf[120];
83 	int e, line;
84 
85 	if (ERR_peek_error() == 0)
86 		return;
87 	fprintf(stderr, "At main.c:%d:\n", l);
88 
89 	while ((e = ERR_get_error_line(&file, &line))) {
90 		ERR_error_string(e, buf);
91 		fprintf(stderr, "- SSL %s: %s:%d\n", buf, file, line);
92 	}
93 }
94 
drain_openssl_errors(void)95 static void drain_openssl_errors(void)
96 {
97 	const char *file;
98 	int line;
99 
100 	if (ERR_peek_error() == 0)
101 		return;
102 	while (ERR_get_error_line(&file, &line)) {}
103 }
104 
105 #define ERR(cond, fmt, ...)				\
106 	do {						\
107 		bool __cond = (cond);			\
108 		display_openssl_errors(__LINE__);	\
109 		if (__cond) {				\
110 			err(1, fmt, ## __VA_ARGS__);	\
111 		}					\
112 	} while(0)
113 
114 static const char *key_pass;
115 
pem_pw_cb(char * buf,int len,int w,void * v)116 static int pem_pw_cb(char *buf, int len, int w, void *v)
117 {
118 	int pwlen;
119 
120 	if (!key_pass)
121 		return -1;
122 
123 	pwlen = strlen(key_pass);
124 	if (pwlen >= len)
125 		return -1;
126 
127 	strcpy(buf, key_pass);
128 
129 	/* If it's wrong, don't keep trying it. */
130 	key_pass = NULL;
131 
132 	return pwlen;
133 }
134 
read_private_key(const char * private_key_name)135 static EVP_PKEY *read_private_key(const char *private_key_name)
136 {
137 	EVP_PKEY *private_key;
138 
139 	if (!strncmp(private_key_name, "pkcs11:", 7)) {
140 		ENGINE *e;
141 
142 		ENGINE_load_builtin_engines();
143 		drain_openssl_errors();
144 		e = ENGINE_by_id("pkcs11");
145 		ERR(!e, "Load PKCS#11 ENGINE");
146 		if (ENGINE_init(e))
147 			drain_openssl_errors();
148 		else
149 			ERR(1, "ENGINE_init");
150 		if (key_pass)
151 			ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0),
152 			    "Set PKCS#11 PIN");
153 		private_key = ENGINE_load_private_key(e, private_key_name,
154 						      NULL, NULL);
155 		ERR(!private_key, "%s", private_key_name);
156 	} else {
157 		BIO *b;
158 
159 		b = BIO_new_file(private_key_name, "rb");
160 		ERR(!b, "%s", private_key_name);
161 		private_key = PEM_read_bio_PrivateKey(b, NULL, pem_pw_cb,
162 						      NULL);
163 		ERR(!private_key, "%s", private_key_name);
164 		BIO_free(b);
165 	}
166 
167 	return private_key;
168 }
169 
read_x509(const char * x509_name)170 static X509 *read_x509(const char *x509_name)
171 {
172 	unsigned char buf[2];
173 	X509 *x509;
174 	BIO *b;
175 	int n;
176 
177 	b = BIO_new_file(x509_name, "rb");
178 	ERR(!b, "%s", x509_name);
179 
180 	/* Look at the first two bytes of the file to determine the encoding */
181 	n = BIO_read(b, buf, 2);
182 	if (n != 2) {
183 		if (BIO_should_retry(b)) {
184 			fprintf(stderr, "%s: Read wanted retry\n", x509_name);
185 			exit(1);
186 		}
187 		if (n >= 0) {
188 			fprintf(stderr, "%s: Short read\n", x509_name);
189 			exit(1);
190 		}
191 		ERR(1, "%s", x509_name);
192 	}
193 
194 	ERR(BIO_reset(b) != 0, "%s", x509_name);
195 
196 	if (buf[0] == 0x30 && buf[1] >= 0x81 && buf[1] <= 0x84)
197 		/* Assume raw DER encoded X.509 */
198 		x509 = d2i_X509_bio(b, NULL);
199 	else
200 		/* Assume PEM encoded X.509 */
201 		x509 = PEM_read_bio_X509(b, NULL, NULL, NULL);
202 
203 	BIO_free(b);
204 	ERR(!x509, "%s", x509_name);
205 
206 	return x509;
207 }
208 
main(int argc,char ** argv)209 int main(int argc, char **argv)
210 {
211 	struct module_signature sig_info = { .id_type = PKEY_ID_PKCS7 };
212 	char *hash_algo = NULL;
213 	char *private_key_name = NULL, *raw_sig_name = NULL;
214 	char *x509_name, *module_name, *dest_name;
215 	bool save_sig = false, replace_orig;
216 	bool sign_only = false;
217 	bool raw_sig = false;
218 	unsigned char buf[4096];
219 	unsigned long module_size, sig_size;
220 	unsigned int use_signed_attrs;
221 	const EVP_MD *digest_algo;
222 	EVP_PKEY *private_key;
223 #ifndef USE_PKCS7
224 	CMS_ContentInfo *cms = NULL;
225 	unsigned int use_keyid = 0;
226 #else
227 	PKCS7 *pkcs7 = NULL;
228 #endif
229 	X509 *x509;
230 	BIO *bd, *bm;
231 	int opt, n;
232 	OpenSSL_add_all_algorithms();
233 	ERR_load_crypto_strings();
234 	ERR_clear_error();
235 
236 	key_pass = getenv("KBUILD_SIGN_PIN");
237 
238 #ifndef USE_PKCS7
239 	use_signed_attrs = CMS_NOATTR;
240 #else
241 	use_signed_attrs = PKCS7_NOATTR;
242 #endif
243 
244 	do {
245 		opt = getopt(argc, argv, "sdpk");
246 		switch (opt) {
247 		case 's': raw_sig = true; break;
248 		case 'p': save_sig = true; break;
249 		case 'd': sign_only = true; save_sig = true; break;
250 #ifndef USE_PKCS7
251 		case 'k': use_keyid = CMS_USE_KEYID; break;
252 #endif
253 		case -1: break;
254 		default: format();
255 		}
256 	} while (opt != -1);
257 
258 	argc -= optind;
259 	argv += optind;
260 	if (argc < 4 || argc > 5)
261 		format();
262 
263 	if (raw_sig) {
264 		raw_sig_name = argv[0];
265 		hash_algo = argv[1];
266 	} else {
267 		hash_algo = argv[0];
268 		private_key_name = argv[1];
269 	}
270 	x509_name = argv[2];
271 	module_name = argv[3];
272 	if (argc == 5 && strcmp(argv[3], argv[4]) != 0) {
273 		dest_name = argv[4];
274 		replace_orig = false;
275 	} else {
276 		ERR(asprintf(&dest_name, "%s.~signed~", module_name) < 0,
277 		    "asprintf");
278 		replace_orig = true;
279 	}
280 
281 #ifdef USE_PKCS7
282 	if (strcmp(hash_algo, "sha1") != 0) {
283 		fprintf(stderr, "sign-file: %s only supports SHA1 signing\n",
284 			OPENSSL_VERSION_TEXT);
285 		exit(3);
286 	}
287 #endif
288 
289 	/* Open the module file */
290 	bm = BIO_new_file(module_name, "rb");
291 	ERR(!bm, "%s", module_name);
292 
293 	if (!raw_sig) {
294 		/* Read the private key and the X.509 cert the PKCS#7 message
295 		 * will point to.
296 		 */
297 		private_key = read_private_key(private_key_name);
298 		x509 = read_x509(x509_name);
299 
300 		/* Digest the module data. */
301 		OpenSSL_add_all_digests();
302 		display_openssl_errors(__LINE__);
303 		digest_algo = EVP_get_digestbyname(hash_algo);
304 		ERR(!digest_algo, "EVP_get_digestbyname");
305 
306 #ifndef USE_PKCS7
307 		/* Load the signature message from the digest buffer. */
308 		cms = CMS_sign(NULL, NULL, NULL, NULL,
309 			       CMS_NOCERTS | CMS_PARTIAL | CMS_BINARY |
310 			       CMS_DETACHED | CMS_STREAM);
311 		ERR(!cms, "CMS_sign");
312 
313 		ERR(!CMS_add1_signer(cms, x509, private_key, digest_algo,
314 				     CMS_NOCERTS | CMS_BINARY |
315 				     CMS_NOSMIMECAP | use_keyid |
316 				     use_signed_attrs),
317 		    "CMS_add1_signer");
318 		ERR(CMS_final(cms, bm, NULL, CMS_NOCERTS | CMS_BINARY) < 0,
319 		    "CMS_final");
320 
321 #else
322 		pkcs7 = PKCS7_sign(x509, private_key, NULL, bm,
323 				   PKCS7_NOCERTS | PKCS7_BINARY |
324 				   PKCS7_DETACHED | use_signed_attrs);
325 		ERR(!pkcs7, "PKCS7_sign");
326 #endif
327 
328 		if (save_sig) {
329 			char *sig_file_name;
330 			BIO *b;
331 
332 			ERR(asprintf(&sig_file_name, "%s.p7s", module_name) < 0,
333 			    "asprintf");
334 			b = BIO_new_file(sig_file_name, "wb");
335 			ERR(!b, "%s", sig_file_name);
336 #ifndef USE_PKCS7
337 			ERR(i2d_CMS_bio_stream(b, cms, NULL, 0) < 0,
338 			    "%s", sig_file_name);
339 #else
340 			ERR(i2d_PKCS7_bio(b, pkcs7) < 0,
341 			    "%s", sig_file_name);
342 #endif
343 			BIO_free(b);
344 		}
345 
346 		if (sign_only) {
347 			BIO_free(bm);
348 			return 0;
349 		}
350 	}
351 
352 	/* Open the destination file now so that we can shovel the module data
353 	 * across as we read it.
354 	 */
355 	bd = BIO_new_file(dest_name, "wb");
356 	ERR(!bd, "%s", dest_name);
357 
358 	/* Append the marker and the PKCS#7 message to the destination file */
359 	ERR(BIO_reset(bm) < 0, "%s", module_name);
360 	while ((n = BIO_read(bm, buf, sizeof(buf))),
361 	       n > 0) {
362 		ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
363 	}
364 	BIO_free(bm);
365 	ERR(n < 0, "%s", module_name);
366 	module_size = BIO_number_written(bd);
367 
368 	if (!raw_sig) {
369 #ifndef USE_PKCS7
370 		ERR(i2d_CMS_bio_stream(bd, cms, NULL, 0) < 0, "%s", dest_name);
371 #else
372 		ERR(i2d_PKCS7_bio(bd, pkcs7) < 0, "%s", dest_name);
373 #endif
374 	} else {
375 		BIO *b;
376 
377 		/* Read the raw signature file and write the data to the
378 		 * destination file
379 		 */
380 		b = BIO_new_file(raw_sig_name, "rb");
381 		ERR(!b, "%s", raw_sig_name);
382 		while ((n = BIO_read(b, buf, sizeof(buf))), n > 0)
383 			ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
384 		BIO_free(b);
385 	}
386 
387 	sig_size = BIO_number_written(bd) - module_size;
388 	sig_info.sig_len = htonl(sig_size);
389 	ERR(BIO_write(bd, &sig_info, sizeof(sig_info)) < 0, "%s", dest_name);
390 	ERR(BIO_write(bd, magic_number, sizeof(magic_number) - 1) < 0, "%s", dest_name);
391 
392 	ERR(BIO_free(bd) < 0, "%s", dest_name);
393 
394 	/* Finally, if we're signing in place, replace the original. */
395 	if (replace_orig)
396 		ERR(rename(dest_name, module_name) < 0, "%s", dest_name);
397 
398 	return 0;
399 }
400