kernel/scripts/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 #define PKEY_ID_PKCS7 2
  27
  28 static __attribute__((noreturn))
  29 void format(void)
  30 {
  31         fprintf(stderr,
  32                 "Usage: scripts/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 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 }