scripts/sign-file.c

   1 /* Sign a module file using the given key.
   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 <getopt.h>
  21 #include <err.h>
  22 #include <arpa/inet.h>
  23 #include <openssl/bio.h>
  24 #include <openssl/evp.h>
  25 #include <openssl/pem.h>
  26 #include <openssl/cms.h>
  27 #include <openssl/err.h>
  28 #include <openssl/engine.h>
  29
  30 struct module_signature {
  31         uint8_t         algo;           /* Public-key crypto algorithm [0] */
  32         uint8_t         hash;           /* Digest algorithm [0] */
  33         uint8_t         id_type;        /* Key identifier type [PKEY_ID_PKCS7] */
  34         uint8_t         signer_len;     /* Length of signer's name [0] */
  35         uint8_t         key_id_len;     /* Length of key identifier [0] */
  36         uint8_t         __pad[3];
  37         uint32_t        sig_len;        /* Length of signature data */
  38 };
  39
  40 #define PKEY_ID_PKCS7 2
  41
  42 static char magic_number[] = "~Module signature appended~\n";
  43
  44 static __attribute__((noreturn))
  45 void format(void)
  46 {
  47         fprintf(stderr,
  48                 "Usage: scripts/sign-file [-dp] <hash algo> <key> <x509> <module> [<dest>]\n");
  49         exit(2);
  50 }
  51
  52 static void display_openssl_errors(int l)
  53 {
  54         const char *file;
  55         char buf[120];
  56         int e, line;
  57
  58         if (ERR_peek_error() == 0)
  59                 return;
  60         fprintf(stderr, "At main.c:%d:\n", l);
  61
  62         while ((e = ERR_get_error_line(&file, &line))) {
  63                 ERR_error_string(e, buf);
  64                 fprintf(stderr, "- SSL %s: %s:%d\n", buf, file, line);
  65         }
  66 }
  67
  68 static void drain_openssl_errors(void)
  69 {
  70         const char *file;
  71         int line;
  72
  73         if (ERR_peek_error() == 0)
  74                 return;
  75         while (ERR_get_error_line(&file, &line)) {}
  76 }
  77
  78 #define ERR(cond, fmt, ...)                             \
  79         do {                                            \
  80                 bool __cond = (cond);                   \
  81                 display_openssl_errors(__LINE__);       \
  82                 if (__cond) {                           \
  83                         err(1, fmt, ## __VA_ARGS__);    \
  84                 }                                       \
  85         } while(0)
  86
  87 static const char *key_pass;
  88
  89 static int pem_pw_cb(char *buf, int len, int w, void *v)
  90 {
  91         int pwlen;
  92
  93         if (!key_pass)
  94                 return -1;
  95
  96         pwlen = strlen(key_pass);
  97         if (pwlen >= len)
  98                 return -1;
  99
 100         strcpy(buf, key_pass);
 101
 102         /* If it's wrong, don't keep trying it. */
 103         key_pass = NULL;
 104
 105         return pwlen;
 106 }
 107
 108 int main(int argc, char **argv)
 109 {
 110         struct module_signature sig_info = { .id_type = PKEY_ID_PKCS7 };
 111         char *hash_algo = NULL;
 112         char *private_key_name, *x509_name, *module_name, *dest_name;
 113         bool save_cms = false, replace_orig;
 114         bool sign_only = false;
 115         unsigned char buf[4096];
 116         unsigned long module_size, cms_size;
 117         unsigned int use_keyid = 0, use_signed_attrs = CMS_NOATTR;
 118         const EVP_MD *digest_algo;
 119         EVP_PKEY *private_key;
 120         CMS_ContentInfo *cms;
 121         X509 *x509;
 122         BIO *b, *bd = NULL, *bm;
 123         int opt, n;
 124
 125         OpenSSL_add_all_algorithms();
 126         ERR_load_crypto_strings();
 127         ERR_clear_error();
 128
 129         key_pass = getenv("KBUILD_SIGN_PIN");
 130
 131         do {
 132                 opt = getopt(argc, argv, "dpk");
 133                 switch (opt) {
 134                 case 'p': save_cms = true; break;
 135                 case 'd': sign_only = true; save_cms = true; break;
 136                 case 'k': use_keyid = CMS_USE_KEYID; break;
 137                 case -1: break;
 138                 default: format();
 139                 }
 140         } while (opt != -1);
 141
 142         argc -= optind;
 143         argv += optind;
 144         if (argc < 4 || argc > 5)
 145                 format();
 146
 147         hash_algo = argv[0];
 148         private_key_name = argv[1];
 149         x509_name = argv[2];
 150         module_name = argv[3];
 151         if (argc == 5) {
 152                 dest_name = argv[4];
 153                 replace_orig = false;
 154         } else {
 155                 ERR(asprintf(&dest_name, "%s.~signed~", module_name) < 0,
 156                     "asprintf");
 157                 replace_orig = true;
 158         }
 159
 160         /* Read the private key and the X.509 cert the PKCS#7 message
 161          * will point to.
 162          */
 163         if (!strncmp(private_key_name, "pkcs11:", 7)) {
 164                 ENGINE *e;
 165
 166                 ENGINE_load_builtin_engines();
 167                 drain_openssl_errors();
 168                 e = ENGINE_by_id("pkcs11");
 169                 ERR(!e, "Load PKCS#11 ENGINE");
 170                 if (ENGINE_init(e))
 171                         drain_openssl_errors();
 172                 else
 173                         ERR(1, "ENGINE_init");
 174                 if (key_pass)
 175                         ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0), "Set PKCS#11 PIN");
 176                 private_key = ENGINE_load_private_key(e, private_key_name, NULL,
 177                                                       NULL);
 178                 ERR(!private_key, "%s", private_key_name);
 179         } else {
 180                 b = BIO_new_file(private_key_name, "rb");
 181                 ERR(!b, "%s", private_key_name);
 182                 private_key = PEM_read_bio_PrivateKey(b, NULL, pem_pw_cb, NULL);
 183                 ERR(!private_key, "%s", private_key_name);
 184                 BIO_free(b);
 185         }
 186
 187         b = BIO_new_file(x509_name, "rb");
 188         ERR(!b, "%s", x509_name);
 189         x509 = d2i_X509_bio(b, NULL); /* Binary encoded X.509 */
 190         if (!x509) {
 191                 ERR(BIO_reset(b) != 1, "%s", x509_name);
 192                 x509 = PEM_read_bio_X509(b, NULL, NULL, NULL); /* PEM encoded X.509 */
 193                 if (x509)
 194                         drain_openssl_errors();
 195         }
 196         BIO_free(b);
 197         ERR(!x509, "%s", x509_name);
 198
 199         /* Open the destination file now so that we can shovel the module data
 200          * across as we read it.
 201          */
 202         if (!sign_only) {
 203                 bd = BIO_new_file(dest_name, "wb");
 204                 ERR(!bd, "%s", dest_name);
 205         }
 206
 207         /* Digest the module data. */
 208         OpenSSL_add_all_digests();
 209         display_openssl_errors(__LINE__);
 210         digest_algo = EVP_get_digestbyname(hash_algo);
 211         ERR(!digest_algo, "EVP_get_digestbyname");
 212
 213         bm = BIO_new_file(module_name, "rb");
 214         ERR(!bm, "%s", module_name);
 215
 216         /* Load the CMS message from the digest buffer. */
 217         cms = CMS_sign(NULL, NULL, NULL, NULL,
 218                        CMS_NOCERTS | CMS_PARTIAL | CMS_BINARY | CMS_DETACHED | CMS_STREAM);
 219         ERR(!cms, "CMS_sign");
 220
 221         ERR(!CMS_add1_signer(cms, x509, private_key, digest_algo,
 222                              CMS_NOCERTS | CMS_BINARY | CMS_NOSMIMECAP |
 223                              use_keyid | use_signed_attrs),
 224             "CMS_sign_add_signer");
 225         ERR(CMS_final(cms, bm, NULL, CMS_NOCERTS | CMS_BINARY) < 0,
 226             "CMS_final");
 227
 228         if (save_cms) {
 229                 char *cms_name;
 230
 231                 ERR(asprintf(&cms_name, "%s.p7s", module_name) < 0, "asprintf");
 232                 b = BIO_new_file(cms_name, "wb");
 233                 ERR(!b, "%s", cms_name);
 234                 ERR(i2d_CMS_bio_stream(b, cms, NULL, 0) < 0, "%s", cms_name);
 235                 BIO_free(b);
 236         }
 237
 238         if (sign_only)
 239                 return 0;
 240
 241         /* Append the marker and the PKCS#7 message to the destination file */
 242         ERR(BIO_reset(bm) < 0, "%s", module_name);
 243         while ((n = BIO_read(bm, buf, sizeof(buf))),
 244                n > 0) {
 245                 ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
 246         }
 247         ERR(n < 0, "%s", module_name);
 248         module_size = BIO_number_written(bd);
 249
 250         ERR(i2d_CMS_bio_stream(bd, cms, NULL, 0) < 0, "%s", dest_name);
 251         cms_size = BIO_number_written(bd) - module_size;
 252         sig_info.sig_len = htonl(cms_size);
 253         ERR(BIO_write(bd, &sig_info, sizeof(sig_info)) < 0, "%s", dest_name);
 254         ERR(BIO_write(bd, magic_number, sizeof(magic_number) - 1) < 0, "%s", dest_name);
 255
 256         ERR(BIO_free(bd) < 0, "%s", dest_name);
 257
 258         /* Finally, if we're signing in place, replace the original. */
 259         if (replace_orig)
 260                 ERR(rename(dest_name, module_name) < 0, "%s", dest_name);
 261
 262         return 0;
 263 }