extract-cert.c

   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 }