xref: /netbsd-src/external/bsd/pkg_install/dist/lib/pkcs7.c (revision f46918ca2125b9b1e7ca5a22c07d1414c618e467)
1 /*	$NetBSD: pkcs7.c,v 1.5 2021/04/10 19:49:59 nia Exp $	*/
2 #if HAVE_CONFIG_H
3 #include "config.h"
4 #endif
5 #include <nbcompat.h>
6 #if HAVE_SYS_CDEFS_H
7 #include <sys/cdefs.h>
8 #endif
9 
10 __RCSID("$NetBSD: pkcs7.c,v 1.5 2021/04/10 19:49:59 nia Exp $");
11 
12 /*-
13  * Copyright (c) 2004, 2008 The NetBSD Foundation, Inc.
14  * All rights reserved.
15  *
16  * This code is derived from software contributed to The NetBSD Foundation
17  * by Love H�rnquist �strand <lha@it.su.se>
18  *
19  * Redistribution and use in source and binary forms, with or without
20  * modification, are permitted provided that the following conditions
21  * are met:
22  * 1. Redistributions of source code must retain the above copyright
23  *    notice, this list of conditions and the following disclaimer.
24  * 2. Redistributions in binary form must reproduce the above copyright
25  *    notice, this list of conditions and the following disclaimer in the
26  *    documentation and/or other materials provided with the distribution.
27  *
28  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
29  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
30  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
31  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
32  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
33  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
34  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
35  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
36  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
37  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
38  * POSSIBILITY OF SUCH DAMAGE.
39  */
40 
41 #if HAVE_ERR_H
42 #include <err.h>
43 #endif
44 
45 #include <openssl/pkcs7.h>
46 #include <openssl/evp.h>
47 #include <openssl/x509.h>
48 #include <openssl/x509v3.h>
49 #include <openssl/pem.h>
50 #include <openssl/err.h>
51 
52 #include "lib.h"
53 
54 #ifndef NS_ANY_CA
55 #define NS_ANY_CA		(NS_SSL_CA|NS_SMIME_CA|NS_OBJSIGN_CA)
56 #endif
57 
58 #if !defined(OPENSSL_VERSION_NUMBER) || (OPENSSL_VERSION_NUMBER < 0x10100000L) || \
59     defined(LIBRESSL_VERSION_NUMBER)
60 #define X509_get_extended_key_usage(x) x->ex_xkusage
61 #define X509_get_extension_flags(x) x->ex_flags
62 #endif
63 
64 static const unsigned int pkg_key_usage = XKU_CODE_SIGN | XKU_SMIME;
65 
STACK_OF(X509)66 static STACK_OF(X509) *
67 file_to_certs(const char *file)
68 {
69 	unsigned long ret;
70 	STACK_OF(X509) *certs;
71 	FILE *f;
72 
73 	if ((f = fopen(file, "r")) == NULL) {
74 		warn("open failed %s", file);
75 		return NULL;
76 	}
77 
78 	certs = sk_X509_new_null();
79 	for (;;) {
80 		X509 *cert;
81 
82 		cert = PEM_read_X509(f, NULL, NULL, NULL);
83 		if (cert == NULL) {
84 			ret = ERR_GET_REASON(ERR_peek_error());
85 			if (ret == PEM_R_NO_START_LINE) {
86 				/* End of file reached. no error */
87 				ERR_clear_error();
88 				break;
89 			}
90 			sk_X509_free(certs);
91 			warnx("Can't read certificate in file: %s", file);
92 			fclose(f);
93 			return NULL;
94 		}
95 		sk_X509_insert(certs, cert, sk_X509_num(certs));
96 	}
97 
98 	fclose(f);
99 
100 	if (sk_X509_num(certs) == 0) {
101 		sk_X509_free(certs);
102 		certs = NULL;
103 		warnx("No certificate found in file %s", file);
104 	}
105 
106 	return certs;
107 }
108 
109 int
easy_pkcs7_verify(const char * content,size_t len,const char * signature,size_t signature_len,const char * anchor,int is_pkg)110 easy_pkcs7_verify(const char *content, size_t len,
111     const char *signature, size_t signature_len,
112     const char *anchor, int is_pkg)
113 {
114 	STACK_OF(X509) *cert_chain, *signers;
115 	X509_STORE *store;
116 	BIO *sig, *in;
117 	PKCS7 *p7;
118 	int i, status;
119 	X509_NAME *name;
120 	char *subject;
121 
122 	OpenSSL_add_all_algorithms();
123 	ERR_load_crypto_strings();
124 
125 	status = -1;
126 
127 	if (cert_chain_file)
128 		cert_chain = file_to_certs(cert_chain_file);
129 	else
130 		cert_chain = NULL;
131 
132 	store = X509_STORE_new();
133 	if (store == NULL) {
134 		sk_X509_free(cert_chain);
135 		warnx("Failed to create certificate store");
136 		return -1;
137 	}
138 
139 	X509_STORE_load_locations(store, anchor, NULL);
140 
141 	in = BIO_new_mem_buf(__UNCONST(content), len);
142 	sig = BIO_new_mem_buf(__UNCONST(signature), signature_len);
143 	signers = NULL;
144 
145 	p7 = PEM_read_bio_PKCS7(sig, NULL, NULL, NULL);
146 	if (p7 == NULL) {
147 		warnx("Failed to parse the signature");
148 		goto cleanup;
149 	}
150 
151 	if (PKCS7_verify(p7, cert_chain, store, in, NULL, 0) != 1) {
152 		warnx("Failed to verify signature");
153 		goto cleanup;
154 	}
155 
156 	signers = PKCS7_get0_signers(p7, NULL, 0);
157 	if (signers == NULL) {
158 		warnx("Failed to get signers");
159 		goto cleanup;
160 	}
161 
162 	if (sk_X509_num(signers) == 0) {
163 		warnx("No signers found");
164 		goto cleanup;
165 	}
166 
167 	for (i = 0; i < sk_X509_num(signers); i++) {
168 		/* Compute ex_xkusage */
169 		X509_check_purpose(sk_X509_value(signers, i), -1, -1);
170 
171 		if (X509_check_ca(sk_X509_value(signers, i))) {
172 			warnx("CA keys are not valid for signatures");
173 			goto cleanup;
174 		}
175 		if (is_pkg) {
176 			if (X509_get_extended_key_usage(sk_X509_value(signers, i)) != pkg_key_usage) {
177 				warnx("Certificate must have CODE SIGNING "
178 				    "and EMAIL PROTECTION property");
179 				goto cleanup;
180 			}
181 		} else {
182 			if (X509_get_extension_flags(sk_X509_value(signers, i)) & EXFLAG_XKUSAGE) {
183 				warnx("Certificate must not have any property");
184 				goto cleanup;
185 			}
186 		}
187 	}
188 
189 	printf("Sigature ok, signed by:\n");
190 
191 	for (i = 0; i < sk_X509_num(signers); i++) {
192 		name = X509_get_subject_name(sk_X509_value(signers, i));
193 		subject = X509_NAME_oneline(name, NULL, 0);
194 
195 		printf("\t%s\n", subject);
196 
197 		OPENSSL_free(subject);
198 	}
199 
200 	status = 0;
201 
202 cleanup:
203 	sk_X509_free(cert_chain);
204 	sk_X509_free(signers);
205 	X509_STORE_free(store);
206 
207 	PKCS7_free(p7);
208 	BIO_free(in);
209 	BIO_free(sig);
210 
211 	return status;
212 }
213 
214 static int
ssl_pass_cb(char * buf,int size,int rwflag,void * u)215 ssl_pass_cb(char *buf, int size, int rwflag, void *u)
216 {
217 
218 	if (EVP_read_pw_string(buf, size, "Passphrase :", 0)) {
219 #if OPENSSL_VERSION >= 0x0090608fL
220 		OPENSSL_cleanse(buf, size);
221 #else
222 		memset(buf, 0, size);
223 #endif
224 		return 0;
225 	}
226 	return strlen(buf);
227 }
228 
229 int
easy_pkcs7_sign(const char * content,size_t len,char ** signature,size_t * signature_len,const char * key_file,const char * cert_file)230 easy_pkcs7_sign(const char *content, size_t len,
231     char **signature, size_t *signature_len,
232     const char *key_file, const char *cert_file)
233 {
234 	FILE *f;
235 	X509 *certificate;
236 	STACK_OF(X509) *c, *cert_chain;
237 	EVP_PKEY *private_key;
238 	char *tmp_sig;
239 	BIO *out, *in;
240 	PKCS7 *p7;
241 	int status;
242 
243 	OpenSSL_add_all_algorithms();
244 	ERR_load_crypto_strings();
245 
246 	status = -1;
247 	private_key = NULL;
248 	cert_chain = NULL;
249 	in = NULL;
250 
251 	c = file_to_certs(cert_file);
252 
253 	if (sk_X509_num(c) != 1) {
254 		warnx("More then one certificate in the certificate file");
255 		goto cleanup;
256 	}
257 	certificate = sk_X509_value(c, 0);
258 
259 	/* Compute ex_kusage */
260 	X509_check_purpose(certificate, -1, 0);
261 
262 	if (X509_check_ca(certificate)) {
263 		warnx("CA keys are not valid for signatures");
264 		goto cleanup;
265 	}
266 
267 	if (X509_get_extended_key_usage(certificate) != pkg_key_usage) {
268 		warnx("Certificate must have CODE SIGNING "
269 		    "and EMAIL PROTECTION property");
270 		goto cleanup;
271 	}
272 
273 	if (cert_chain_file)
274 		cert_chain = file_to_certs(cert_chain_file);
275 
276 	if ((f = fopen(key_file, "r")) == NULL) {
277 		warn("Failed to open private key file %s", key_file);
278 		goto cleanup;
279 	}
280 	private_key = PEM_read_PrivateKey(f, NULL, ssl_pass_cb, NULL);
281 	fclose(f);
282 	if (private_key == NULL) {
283 		warnx("Can't read private key: %s", key_file);
284 		goto cleanup;
285 	}
286 
287 	if (X509_check_private_key(certificate, private_key) != 1) {
288 		warnx("The private key %s doesn't match the certificate %s",
289 		    key_file, cert_file);
290 		goto cleanup;
291 	}
292 
293 	in = BIO_new_mem_buf(__UNCONST(content), len);
294 
295 	p7 = PKCS7_sign(certificate, private_key, cert_chain, in,
296 	    PKCS7_DETACHED|PKCS7_NOATTR|PKCS7_BINARY);
297 	if (p7 == NULL) {
298 		warnx("Failed to create signature structure");
299 		goto cleanup;
300 	}
301 
302 	out = BIO_new(BIO_s_mem());
303 	PEM_write_bio_PKCS7(out, p7);
304 	*signature_len = BIO_get_mem_data(out, &tmp_sig);
305 	*signature = xmalloc(*signature_len);
306 	memcpy(*signature, tmp_sig, *signature_len);
307 	BIO_free_all(out);
308 
309 	PKCS7_free(p7);
310 
311 	status = 0;
312 
313 cleanup:
314 	sk_X509_free(c);
315 	sk_X509_free(cert_chain);
316 	EVP_PKEY_free(private_key);
317 	BIO_free(in);
318 
319 	return status;
320 }
321