certs/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 bool 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 (verbose)
  94                 fprintf(stderr, "Extracted cert: %s\n", buf);
  95 }
  96
  97 int main(int argc, char **argv)
  98 {
  99         char *cert_src;
 100         char *verbose_env;
 101
 102         OpenSSL_add_all_algorithms();
 103         ERR_load_crypto_strings();
 104         ERR_clear_error();
 105
 106         verbose_env = getenv("KBUILD_VERBOSE");
 107         if (verbose_env && strchr(verbose_env, '1'))
 108                 verbose = true;
 109
 110         key_pass = getenv("KBUILD_SIGN_PIN");
 111
 112         if (argc != 3)
 113                 format();
 114
 115         cert_src = argv[1];
 116         cert_dst = argv[2];
 117
 118         if (!cert_src[0]) {
 119                 /* Invoked with no input; create empty file */
 120                 FILE *f = fopen(cert_dst, "wb");
 121                 ERR(!f, "%s", cert_dst);
 122                 fclose(f);
 123                 exit(0);
 124         } else if (!strncmp(cert_src, "pkcs11:", 7)) {
 125                 ENGINE *e;
 126                 struct {
 127                         const char *cert_id;
 128                         X509 *cert;
 129                 } parms;
 130
 131                 parms.cert_id = cert_src;
 132                 parms.cert = NULL;
 133
 134                 ENGINE_load_builtin_engines();
 135                 drain_openssl_errors();
 136                 e = ENGINE_by_id("pkcs11");
 137                 ERR(!e, "Load PKCS#11 ENGINE");
 138                 if (ENGINE_init(e))
 139                         drain_openssl_errors();
 140                 else
 141                         ERR(1, "ENGINE_init");
 142                 if (key_pass)
 143                         ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0), "Set PKCS#11 PIN");
 144                 ENGINE_ctrl_cmd(e, "LOAD_CERT_CTRL", 0, &parms, NULL, 1);
 145                 ERR(!parms.cert, "Get X.509 from PKCS#11");
 146                 write_cert(parms.cert);
 147         } else {
 148                 BIO *b;
 149                 X509 *x509;
 150
 151                 b = BIO_new_file(cert_src, "rb");
 152                 ERR(!b, "%s", cert_src);
 153
 154                 while (1) {
 155                         x509 = PEM_read_bio_X509(b, NULL, NULL, NULL);
 156                         if (wb && !x509) {
 157                                 unsigned long err = ERR_peek_last_error();
 158                                 if (ERR_GET_LIB(err) == ERR_LIB_PEM &&
 159                                     ERR_GET_REASON(err) == PEM_R_NO_START_LINE) {
 160                                         ERR_clear_error();
 161                                         break;
 162                                 }
 163                         }
 164                         ERR(!x509, "%s", cert_src);
 165                         write_cert(x509);
 166                 }
 167         }
 168
 169         BIO_free(wb);
 170
 171         return 0;
 172 }