xref: /openbmc/linux/certs/extract-cert.c (revision 9a29f5fc)
1 /* Extract X.509 certificate in DER form from PKCS#11 or PEM.
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 <err.h>
21 #include <openssl/bio.h>
22 #include <openssl/pem.h>
23 #include <openssl/err.h>
24 #include <openssl/engine.h>
25 
26 /*
27  * OpenSSL 3.0 deprecates the OpenSSL's ENGINE API.
28  *
29  * Remove this if/when that API is no longer used
30  */
31 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
32 
33 #define PKEY_ID_PKCS7 2
34 
35 static __attribute__((noreturn))
36 void format(void)
37 {
38 	fprintf(stderr,
39 		"Usage: extract-cert <source> <dest>\n");
40 	exit(2);
41 }
42 
43 static void display_openssl_errors(int l)
44 {
45 	const char *file;
46 	char buf[120];
47 	int e, line;
48 
49 	if (ERR_peek_error() == 0)
50 		return;
51 	fprintf(stderr, "At main.c:%d:\n", l);
52 
53 	while ((e = ERR_get_error_line(&file, &line))) {
54 		ERR_error_string(e, buf);
55 		fprintf(stderr, "- SSL %s: %s:%d\n", buf, file, line);
56 	}
57 }
58 
59 static void drain_openssl_errors(void)
60 {
61 	const char *file;
62 	int line;
63 
64 	if (ERR_peek_error() == 0)
65 		return;
66 	while (ERR_get_error_line(&file, &line)) {}
67 }
68 
69 #define ERR(cond, fmt, ...)				\
70 	do {						\
71 		bool __cond = (cond);			\
72 		display_openssl_errors(__LINE__);	\
73 		if (__cond) {				\
74 			err(1, fmt, ## __VA_ARGS__);	\
75 		}					\
76 	} while(0)
77 
78 static const char *key_pass;
79 static BIO *wb;
80 static char *cert_dst;
81 static int kbuild_verbose;
82 
83 static void write_cert(X509 *x509)
84 {
85 	char buf[200];
86 
87 	if (!wb) {
88 		wb = BIO_new_file(cert_dst, "wb");
89 		ERR(!wb, "%s", cert_dst);
90 	}
91 	X509_NAME_oneline(X509_get_subject_name(x509), buf, sizeof(buf));
92 	ERR(!i2d_X509_bio(wb, x509), "%s", cert_dst);
93 	if (kbuild_verbose)
94 		fprintf(stderr, "Extracted cert: %s\n", buf);
95 }
96 
97 int main(int argc, char **argv)
98 {
99 	char *cert_src;
100 
101 	OpenSSL_add_all_algorithms();
102 	ERR_load_crypto_strings();
103 	ERR_clear_error();
104 
105 	kbuild_verbose = atoi(getenv("KBUILD_VERBOSE")?:"0");
106 
107         key_pass = getenv("KBUILD_SIGN_PIN");
108 
109 	if (argc != 3)
110 		format();
111 
112 	cert_src = argv[1];
113 	cert_dst = argv[2];
114 
115 	if (!cert_src[0]) {
116 		/* Invoked with no input; create empty file */
117 		FILE *f = fopen(cert_dst, "wb");
118 		ERR(!f, "%s", cert_dst);
119 		fclose(f);
120 		exit(0);
121 	} else if (!strncmp(cert_src, "pkcs11:", 7)) {
122 		ENGINE *e;
123 		struct {
124 			const char *cert_id;
125 			X509 *cert;
126 		} parms;
127 
128 		parms.cert_id = cert_src;
129 		parms.cert = NULL;
130 
131 		ENGINE_load_builtin_engines();
132 		drain_openssl_errors();
133 		e = ENGINE_by_id("pkcs11");
134 		ERR(!e, "Load PKCS#11 ENGINE");
135 		if (ENGINE_init(e))
136 			drain_openssl_errors();
137 		else
138 			ERR(1, "ENGINE_init");
139 		if (key_pass)
140 			ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0), "Set PKCS#11 PIN");
141 		ENGINE_ctrl_cmd(e, "LOAD_CERT_CTRL", 0, &parms, NULL, 1);
142 		ERR(!parms.cert, "Get X.509 from PKCS#11");
143 		write_cert(parms.cert);
144 	} else {
145 		BIO *b;
146 		X509 *x509;
147 
148 		b = BIO_new_file(cert_src, "rb");
149 		ERR(!b, "%s", cert_src);
150 
151 		while (1) {
152 			x509 = PEM_read_bio_X509(b, NULL, NULL, NULL);
153 			if (wb && !x509) {
154 				unsigned long err = ERR_peek_last_error();
155 				if (ERR_GET_LIB(err) == ERR_LIB_PEM &&
156 				    ERR_GET_REASON(err) == PEM_R_NO_START_LINE) {
157 					ERR_clear_error();
158 					break;
159 				}
160 			}
161 			ERR(!x509, "%s", cert_src);
162 			write_cert(x509);
163 		}
164 	}
165 
166 	BIO_free(wb);
167 
168 	return 0;
169 }
170