xref: /openbmc/linux/certs/extract-cert.c (revision b625fe69)
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 #define PKEY_ID_PKCS7 2
27 
28 static __attribute__((noreturn))
29 void format(void)
30 {
31 	fprintf(stderr,
32 		"Usage: extract-cert <source> <dest>\n");
33 	exit(2);
34 }
35 
36 static void display_openssl_errors(int l)
37 {
38 	const char *file;
39 	char buf[120];
40 	int e, line;
41 
42 	if (ERR_peek_error() == 0)
43 		return;
44 	fprintf(stderr, "At main.c:%d:\n", l);
45 
46 	while ((e = ERR_get_error_line(&file, &line))) {
47 		ERR_error_string(e, buf);
48 		fprintf(stderr, "- SSL %s: %s:%d\n", buf, file, line);
49 	}
50 }
51 
52 static void drain_openssl_errors(void)
53 {
54 	const char *file;
55 	int line;
56 
57 	if (ERR_peek_error() == 0)
58 		return;
59 	while (ERR_get_error_line(&file, &line)) {}
60 }
61 
62 #define ERR(cond, fmt, ...)				\
63 	do {						\
64 		bool __cond = (cond);			\
65 		display_openssl_errors(__LINE__);	\
66 		if (__cond) {				\
67 			err(1, fmt, ## __VA_ARGS__);	\
68 		}					\
69 	} while(0)
70 
71 static const char *key_pass;
72 static BIO *wb;
73 static char *cert_dst;
74 static int kbuild_verbose;
75 
76 static void write_cert(X509 *x509)
77 {
78 	char buf[200];
79 
80 	if (!wb) {
81 		wb = BIO_new_file(cert_dst, "wb");
82 		ERR(!wb, "%s", cert_dst);
83 	}
84 	X509_NAME_oneline(X509_get_subject_name(x509), buf, sizeof(buf));
85 	ERR(!i2d_X509_bio(wb, x509), "%s", cert_dst);
86 	if (kbuild_verbose)
87 		fprintf(stderr, "Extracted cert: %s\n", buf);
88 }
89 
90 int main(int argc, char **argv)
91 {
92 	char *cert_src;
93 
94 	OpenSSL_add_all_algorithms();
95 	ERR_load_crypto_strings();
96 	ERR_clear_error();
97 
98 	kbuild_verbose = atoi(getenv("KBUILD_VERBOSE")?:"0");
99 
100         key_pass = getenv("KBUILD_SIGN_PIN");
101 
102 	if (argc != 3)
103 		format();
104 
105 	cert_src = argv[1];
106 	cert_dst = argv[2];
107 
108 	if (!cert_src[0]) {
109 		/* Invoked with no input; create empty file */
110 		FILE *f = fopen(cert_dst, "wb");
111 		ERR(!f, "%s", cert_dst);
112 		fclose(f);
113 		exit(0);
114 	} else if (!strncmp(cert_src, "pkcs11:", 7)) {
115 		ENGINE *e;
116 		struct {
117 			const char *cert_id;
118 			X509 *cert;
119 		} parms;
120 
121 		parms.cert_id = cert_src;
122 		parms.cert = NULL;
123 
124 		ENGINE_load_builtin_engines();
125 		drain_openssl_errors();
126 		e = ENGINE_by_id("pkcs11");
127 		ERR(!e, "Load PKCS#11 ENGINE");
128 		if (ENGINE_init(e))
129 			drain_openssl_errors();
130 		else
131 			ERR(1, "ENGINE_init");
132 		if (key_pass)
133 			ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0), "Set PKCS#11 PIN");
134 		ENGINE_ctrl_cmd(e, "LOAD_CERT_CTRL", 0, &parms, NULL, 1);
135 		ERR(!parms.cert, "Get X.509 from PKCS#11");
136 		write_cert(parms.cert);
137 	} else {
138 		BIO *b;
139 		X509 *x509;
140 
141 		b = BIO_new_file(cert_src, "rb");
142 		ERR(!b, "%s", cert_src);
143 
144 		while (1) {
145 			x509 = PEM_read_bio_X509(b, NULL, NULL, NULL);
146 			if (wb && !x509) {
147 				unsigned long err = ERR_peek_last_error();
148 				if (ERR_GET_LIB(err) == ERR_LIB_PEM &&
149 				    ERR_GET_REASON(err) == PEM_R_NO_START_LINE) {
150 					ERR_clear_error();
151 					break;
152 				}
153 			}
154 			ERR(!x509, "%s", cert_src);
155 			write_cert(x509);
156 		}
157 	}
158 
159 	BIO_free(wb);
160 
161 	return 0;
162 }
163