scripts/sign-file.c

   1 /* Sign a module file using the given key.
   2  *
   3  * Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11 #define _GNU_SOURCE
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14 #include <stdint.h>
  15 #include <stdbool.h>
  16 #include <string.h>
  17 #include <getopt.h>
  18 #include <err.h>
  19 #include <arpa/inet.h>
  20 #include <openssl/bio.h>
  21 #include <openssl/evp.h>
  22 #include <openssl/pem.h>
  23 #include <openssl/pkcs7.h>
  24 #include <openssl/err.h>
  25
  26 struct module_signature {
  27         uint8_t         algo;           /* Public-key crypto algorithm [0] */
  28         uint8_t         hash;           /* Digest algorithm [0] */
  29         uint8_t         id_type;        /* Key identifier type [PKEY_ID_PKCS7] */
  30         uint8_t         signer_len;     /* Length of signer's name [0] */
  31         uint8_t         key_id_len;     /* Length of key identifier [0] */
  32         uint8_t         __pad[3];
  33         uint32_t        sig_len;        /* Length of signature data */
  34 };
  35
  36 #define PKEY_ID_PKCS7 2
  37
  38 static char magic_number[] = "~Module signature appended~\n";
  39
  40 static __attribute__((noreturn))
  41 void format(void)
  42 {
  43         fprintf(stderr,
  44                 "Usage: scripts/sign-file [-dp] <hash algo> <key> <x509> <module> [<dest>]\n");
  45         exit(2);
  46 }
  47
  48 static void display_openssl_errors(int l)
  49 {
  50         const char *file;
  51         char buf[120];
  52         int e, line;
  53
  54         if (ERR_peek_error() == 0)
  55                 return;
  56         fprintf(stderr, "At main.c:%d:\n", l);
  57
  58         while ((e = ERR_get_error_line(&file, &line))) {
  59                 ERR_error_string(e, buf);
  60                 fprintf(stderr, "- SSL %s: %s:%d\n", buf, file, line);
  61         }
  62 }
  63
  64 static void drain_openssl_errors(void)
  65 {
  66         const char *file;
  67         int line;
  68
  69         if (ERR_peek_error() == 0)
  70                 return;
  71         while (ERR_get_error_line(&file, &line)) {}
  72 }
  73
  74 #define ERR(cond, fmt, ...)                             \
  75         do {                                            \
  76                 bool __cond = (cond);                   \
  77                 display_openssl_errors(__LINE__);       \
  78                 if (__cond) {                           \
  79                         err(1, fmt, ## __VA_ARGS__);    \
  80                 }                                       \
  81         } while(0)
  82
  83 static const char *key_pass;
  84
  85 static int pem_pw_cb(char *buf, int len, int w, void *v)
  86 {
  87         int pwlen;
  88
  89         if (!key_pass)
  90                 return -1;
  91
  92         pwlen = strlen(key_pass);
  93         if (pwlen >= len)
  94                 return -1;
  95
  96         strcpy(buf, key_pass);
  97
  98         /* If it's wrong, don't keep trying it. */
  99         key_pass = NULL;
 100
 101         return pwlen;
 102 }
 103
 104 int main(int argc, char **argv)
 105 {
 106         struct module_signature sig_info = { .id_type = PKEY_ID_PKCS7 };
 107         char *hash_algo = NULL;
 108         char *private_key_name, *x509_name, *module_name, *dest_name;
 109         bool save_pkcs7 = false, replace_orig;
 110         bool sign_only = false;
 111         unsigned char buf[4096];
 112         unsigned long module_size, pkcs7_size;
 113         const EVP_MD *digest_algo;
 114         EVP_PKEY *private_key;
 115         PKCS7 *pkcs7;
 116         X509 *x509;
 117         BIO *b, *bd = NULL, *bm;
 118         int opt, n;
 119
 120         OpenSSL_add_all_algorithms();
 121         ERR_load_crypto_strings();
 122         ERR_clear_error();
 123
 124         key_pass = getenv("KBUILD_SIGN_PIN");
 125
 126         do {
 127                 opt = getopt(argc, argv, "dp");
 128                 switch (opt) {
 129                 case 'p': save_pkcs7 = true; break;
 130                 case 'd': sign_only = true; save_pkcs7 = true; break;
 131                 case -1: break;
 132                 default: format();
 133                 }
 134         } while (opt != -1);
 135
 136         argc -= optind;
 137         argv += optind;
 138         if (argc < 4 || argc > 5)
 139                 format();
 140
 141         hash_algo = argv[0];
 142         private_key_name = argv[1];
 143         x509_name = argv[2];
 144         module_name = argv[3];
 145         if (argc == 5) {
 146                 dest_name = argv[4];
 147                 replace_orig = false;
 148         } else {
 149                 ERR(asprintf(&dest_name, "%s.~signed~", module_name) < 0,
 150                     "asprintf");
 151                 replace_orig = true;
 152         }
 153
 154         /* Read the private key and the X.509 cert the PKCS#7 message
 155          * will point to.
 156          */
 157         b = BIO_new_file(private_key_name, "rb");
 158         ERR(!b, "%s", private_key_name);
 159         private_key = PEM_read_bio_PrivateKey(b, NULL, pem_pw_cb, NULL);
 160         ERR(!private_key, "%s", private_key_name);
 161         BIO_free(b);
 162
 163         b = BIO_new_file(x509_name, "rb");
 164         ERR(!b, "%s", x509_name);
 165         x509 = d2i_X509_bio(b, NULL); /* Binary encoded X.509 */
 166         if (!x509) {
 167                 BIO_reset(b);
 168                 x509 = PEM_read_bio_X509(b, NULL, NULL, NULL); /* PEM encoded X.509 */
 169                 if (x509)
 170                         drain_openssl_errors();
 171         }
 172         BIO_free(b);
 173         ERR(!x509, "%s", x509_name);
 174
 175         /* Open the destination file now so that we can shovel the module data
 176          * across as we read it.
 177          */
 178         if (!sign_only) {
 179                 bd = BIO_new_file(dest_name, "wb");
 180                 ERR(!bd, "%s", dest_name);
 181         }
 182
 183         /* Digest the module data. */
 184         OpenSSL_add_all_digests();
 185         display_openssl_errors(__LINE__);
 186         digest_algo = EVP_get_digestbyname(hash_algo);
 187         ERR(!digest_algo, "EVP_get_digestbyname");
 188
 189         bm = BIO_new_file(module_name, "rb");
 190         ERR(!bm, "%s", module_name);
 191
 192         /* Load the PKCS#7 message from the digest buffer. */
 193         pkcs7 = PKCS7_sign(NULL, NULL, NULL, NULL,
 194                            PKCS7_NOCERTS | PKCS7_PARTIAL | PKCS7_BINARY | PKCS7_DETACHED | PKCS7_STREAM);
 195         ERR(!pkcs7, "PKCS7_sign");
 196
 197         ERR(!PKCS7_sign_add_signer(pkcs7, x509, private_key, digest_algo, PKCS7_NOCERTS | PKCS7_BINARY),
 198             "PKCS7_sign_add_signer");
 199         ERR(PKCS7_final(pkcs7, bm, PKCS7_NOCERTS | PKCS7_BINARY) < 0,
 200             "PKCS7_final");
 201
 202         if (save_pkcs7) {
 203                 char *pkcs7_name;
 204
 205                 ERR(asprintf(&pkcs7_name, "%s.pkcs7", module_name) < 0, "asprintf");
 206                 b = BIO_new_file(pkcs7_name, "wb");
 207                 ERR(!b, "%s", pkcs7_name);
 208                 ERR(i2d_PKCS7_bio_stream(b, pkcs7, NULL, 0) < 0, "%s", pkcs7_name);
 209                 BIO_free(b);
 210         }
 211
 212         if (sign_only)
 213                 return 0;
 214
 215         /* Append the marker and the PKCS#7 message to the destination file */
 216         ERR(BIO_reset(bm) < 0, "%s", module_name);
 217         while ((n = BIO_read(bm, buf, sizeof(buf))),
 218                n > 0) {
 219                 ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
 220         }
 221         ERR(n < 0, "%s", module_name);
 222         module_size = BIO_number_written(bd);
 223
 224         ERR(i2d_PKCS7_bio_stream(bd, pkcs7, NULL, 0) < 0, "%s", dest_name);
 225         pkcs7_size = BIO_number_written(bd) - module_size;
 226         sig_info.sig_len = htonl(pkcs7_size);
 227         ERR(BIO_write(bd, &sig_info, sizeof(sig_info)) < 0, "%s", dest_name);
 228         ERR(BIO_write(bd, magic_number, sizeof(magic_number) - 1) < 0, "%s", dest_name);
 229
 230         ERR(BIO_free(bd) < 0, "%s", dest_name);
 231
 232         /* Finally, if we're signing in place, replace the original. */
 233         if (replace_orig)
 234                 ERR(rename(dest_name, module_name) < 0, "%s", dest_name);
 235
 236         return 0;
 237 }