root/scripts/sign-file.c

DEFINITIONS

1. format
2. display_openssl_errors
3. drain_openssl_errors
4. pem_pw_cb
5. read_private_key
6. read_x509
7. main

   1 /* Sign a module file using the given key.
   2  *
   3  * Copyright © 2014-2016 Red Hat, Inc. All Rights Reserved.
   4  * Copyright © 2015      Intel Corporation.
   5  * Copyright © 2016      Hewlett Packard Enterprise Development LP
   6  *
   7  * Authors: David Howells <dhowells@redhat.com>
   8  *          David Woodhouse <dwmw2@infradead.org>
   9  *          Juerg Haefliger <juerg.haefliger@hpe.com>
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU Lesser General Public License
  13  * as published by the Free Software Foundation; either version 2.1
  14  * of the licence, or (at your option) any later version.
  15  */
  16 #define _GNU_SOURCE
  17 #include <stdio.h>
  18 #include <stdlib.h>
  19 #include <stdint.h>
  20 #include <stdbool.h>
  21 #include <string.h>
  22 #include <getopt.h>
  23 #include <err.h>
  24 #include <arpa/inet.h>
  25 #include <openssl/opensslv.h>
  26 #include <openssl/bio.h>
  27 #include <openssl/evp.h>
  28 #include <openssl/pem.h>
  29 #include <openssl/err.h>
  30 #include <openssl/engine.h>
  31 
  32 /*
  33  * Use CMS if we have openssl-1.0.0 or newer available - otherwise we have to
  34  * assume that it's not available and its header file is missing and that we
  35  * should use PKCS#7 instead.  Switching to the older PKCS#7 format restricts
  36  * the options we have on specifying the X.509 certificate we want.
  37  *
  38  * Further, older versions of OpenSSL don't support manually adding signers to
  39  * the PKCS#7 message so have to accept that we get a certificate included in
  40  * the signature message.  Nor do such older versions of OpenSSL support
  41  * signing with anything other than SHA1 - so we're stuck with that if such is
  42  * the case.
  43  */
  44 #if defined(LIBRESSL_VERSION_NUMBER) || \
  45         OPENSSL_VERSION_NUMBER < 0x10000000L || \
  46         defined(OPENSSL_NO_CMS)
  47 #define USE_PKCS7
  48 #endif
  49 #ifndef USE_PKCS7
  50 #include <openssl/cms.h>
  51 #else
  52 #include <openssl/pkcs7.h>
  53 #endif
  54 
  55 struct module_signature {
  56         uint8_t         algo;           /* Public-key crypto algorithm [0] */
  57         uint8_t         hash;           /* Digest algorithm [0] */
  58         uint8_t         id_type;        /* Key identifier type [PKEY_ID_PKCS7] */
  59         uint8_t         signer_len;     /* Length of signer's name [0] */
  60         uint8_t         key_id_len;     /* Length of key identifier [0] */
  61         uint8_t         __pad[3];
  62         uint32_t        sig_len;        /* Length of signature data */
  63 };
  64 
  65 #define PKEY_ID_PKCS7 2
  66 
  67 static char magic_number[] = "~Module signature appended~\n";
  68 
  69 static __attribute__((noreturn))
  70 void format(void)
  71 {
  72         fprintf(stderr,
  73                 "Usage: scripts/sign-file [-dp] <hash algo> <key> <x509> <module> [<dest>]\n");
  74         fprintf(stderr,
  75                 "       scripts/sign-file -s <raw sig> <hash algo> <x509> <module> [<dest>]\n");
  76         exit(2);
  77 }
  78 
  79 static void display_openssl_errors(int l)
  80 {
  81         const char *file;
  82         char buf[120];
  83         int e, line;
  84 
  85         if (ERR_peek_error() == 0)
  86                 return;
  87         fprintf(stderr, "At main.c:%d:\n", l);
  88 
  89         while ((e = ERR_get_error_line(&file, &line))) {
  90                 ERR_error_string(e, buf);
  91                 fprintf(stderr, "- SSL %s: %s:%d\n", buf, file, line);
  92         }
  93 }
  94 
  95 static void drain_openssl_errors(void)
  96 {
  97         const char *file;
  98         int line;
  99 
 100         if (ERR_peek_error() == 0)
 101                 return;
 102         while (ERR_get_error_line(&file, &line)) {}
 103 }
 104 
 105 #define ERR(cond, fmt, ...)                             \
 106         do {                                            \
 107                 bool __cond = (cond);                   \
 108                 display_openssl_errors(__LINE__);       \
 109                 if (__cond) {                           \
 110                         err(1, fmt, ## __VA_ARGS__);    \
 111                 }                                       \
 112         } while(0)
 113 
 114 static const char *key_pass;
 115 
 116 static int pem_pw_cb(char *buf, int len, int w, void *v)
 117 {
 118         int pwlen;
 119 
 120         if (!key_pass)
 121                 return -1;
 122 
 123         pwlen = strlen(key_pass);
 124         if (pwlen >= len)
 125                 return -1;
 126 
 127         strcpy(buf, key_pass);
 128 
 129         /* If it's wrong, don't keep trying it. */
 130         key_pass = NULL;
 131 
 132         return pwlen;
 133 }
 134 
 135 static EVP_PKEY *read_private_key(const char *private_key_name)
 136 {
 137         EVP_PKEY *private_key;
 138 
 139         if (!strncmp(private_key_name, "pkcs11:", 7)) {
 140                 ENGINE *e;
 141 
 142                 ENGINE_load_builtin_engines();
 143                 drain_openssl_errors();
 144                 e = ENGINE_by_id("pkcs11");
 145                 ERR(!e, "Load PKCS#11 ENGINE");
 146                 if (ENGINE_init(e))
 147                         drain_openssl_errors();
 148                 else
 149                         ERR(1, "ENGINE_init");
 150                 if (key_pass)
 151                         ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0),
 152                             "Set PKCS#11 PIN");
 153                 private_key = ENGINE_load_private_key(e, private_key_name,
 154                                                       NULL, NULL);
 155                 ERR(!private_key, "%s", private_key_name);
 156         } else {
 157                 BIO *b;
 158 
 159                 b = BIO_new_file(private_key_name, "rb");
 160                 ERR(!b, "%s", private_key_name);
 161                 private_key = PEM_read_bio_PrivateKey(b, NULL, pem_pw_cb,
 162                                                       NULL);
 163                 ERR(!private_key, "%s", private_key_name);
 164                 BIO_free(b);
 165         }
 166 
 167         return private_key;
 168 }
 169 
 170 static X509 *read_x509(const char *x509_name)
 171 {
 172         unsigned char buf[2];
 173         X509 *x509;
 174         BIO *b;
 175         int n;
 176 
 177         b = BIO_new_file(x509_name, "rb");
 178         ERR(!b, "%s", x509_name);
 179 
 180         /* Look at the first two bytes of the file to determine the encoding */
 181         n = BIO_read(b, buf, 2);
 182         if (n != 2) {
 183                 if (BIO_should_retry(b)) {
 184                         fprintf(stderr, "%s: Read wanted retry\n", x509_name);
 185                         exit(1);
 186                 }
 187                 if (n >= 0) {
 188                         fprintf(stderr, "%s: Short read\n", x509_name);
 189                         exit(1);
 190                 }
 191                 ERR(1, "%s", x509_name);
 192         }
 193 
 194         ERR(BIO_reset(b) != 0, "%s", x509_name);
 195 
 196         if (buf[0] == 0x30 && buf[1] >= 0x81 && buf[1] <= 0x84)
 197                 /* Assume raw DER encoded X.509 */
 198                 x509 = d2i_X509_bio(b, NULL);
 199         else
 200                 /* Assume PEM encoded X.509 */
 201                 x509 = PEM_read_bio_X509(b, NULL, NULL, NULL);
 202 
 203         BIO_free(b);
 204         ERR(!x509, "%s", x509_name);
 205 
 206         return x509;
 207 }
 208 
 209 int main(int argc, char **argv)
 210 {
 211         struct module_signature sig_info = { .id_type = PKEY_ID_PKCS7 };
 212         char *hash_algo = NULL;
 213         char *private_key_name = NULL, *raw_sig_name = NULL;
 214         char *x509_name, *module_name, *dest_name;
 215         bool save_sig = false, replace_orig;
 216         bool sign_only = false;
 217         bool raw_sig = false;
 218         unsigned char buf[4096];
 219         unsigned long module_size, sig_size;
 220         unsigned int use_signed_attrs;
 221         const EVP_MD *digest_algo;
 222         EVP_PKEY *private_key;
 223 #ifndef USE_PKCS7
 224         CMS_ContentInfo *cms = NULL;
 225         unsigned int use_keyid = 0;
 226 #else
 227         PKCS7 *pkcs7 = NULL;
 228 #endif
 229         X509 *x509;
 230         BIO *bd, *bm;
 231         int opt, n;
 232         OpenSSL_add_all_algorithms();
 233         ERR_load_crypto_strings();
 234         ERR_clear_error();
 235 
 236         key_pass = getenv("KBUILD_SIGN_PIN");
 237 
 238 #ifndef USE_PKCS7
 239         use_signed_attrs = CMS_NOATTR;
 240 #else
 241         use_signed_attrs = PKCS7_NOATTR;
 242 #endif
 243 
 244         do {
 245                 opt = getopt(argc, argv, "sdpk");
 246                 switch (opt) {
 247                 case 's': raw_sig = true; break;
 248                 case 'p': save_sig = true; break;
 249                 case 'd': sign_only = true; save_sig = true; break;
 250 #ifndef USE_PKCS7
 251                 case 'k': use_keyid = CMS_USE_KEYID; break;
 252 #endif
 253                 case -1: break;
 254                 default: format();
 255                 }
 256         } while (opt != -1);
 257 
 258         argc -= optind;
 259         argv += optind;
 260         if (argc < 4 || argc > 5)
 261                 format();
 262 
 263         if (raw_sig) {
 264                 raw_sig_name = argv[0];
 265                 hash_algo = argv[1];
 266         } else {
 267                 hash_algo = argv[0];
 268                 private_key_name = argv[1];
 269         }
 270         x509_name = argv[2];
 271         module_name = argv[3];
 272         if (argc == 5 && strcmp(argv[3], argv[4]) != 0) {
 273                 dest_name = argv[4];
 274                 replace_orig = false;
 275         } else {
 276                 ERR(asprintf(&dest_name, "%s.~signed~", module_name) < 0,
 277                     "asprintf");
 278                 replace_orig = true;
 279         }
 280 
 281 #ifdef USE_PKCS7
 282         if (strcmp(hash_algo, "sha1") != 0) {
 283                 fprintf(stderr, "sign-file: %s only supports SHA1 signing\n",
 284                         OPENSSL_VERSION_TEXT);
 285                 exit(3);
 286         }
 287 #endif
 288 
 289         /* Open the module file */
 290         bm = BIO_new_file(module_name, "rb");
 291         ERR(!bm, "%s", module_name);
 292 
 293         if (!raw_sig) {
 294                 /* Read the private key and the X.509 cert the PKCS#7 message
 295                  * will point to.
 296                  */
 297                 private_key = read_private_key(private_key_name);
 298                 x509 = read_x509(x509_name);
 299 
 300                 /* Digest the module data. */
 301                 OpenSSL_add_all_digests();
 302                 display_openssl_errors(__LINE__);
 303                 digest_algo = EVP_get_digestbyname(hash_algo);
 304                 ERR(!digest_algo, "EVP_get_digestbyname");
 305 
 306 #ifndef USE_PKCS7
 307                 /* Load the signature message from the digest buffer. */
 308                 cms = CMS_sign(NULL, NULL, NULL, NULL,
 309                                CMS_NOCERTS | CMS_PARTIAL | CMS_BINARY |
 310                                CMS_DETACHED | CMS_STREAM);
 311                 ERR(!cms, "CMS_sign");
 312 
 313                 ERR(!CMS_add1_signer(cms, x509, private_key, digest_algo,
 314                                      CMS_NOCERTS | CMS_BINARY |
 315                                      CMS_NOSMIMECAP | use_keyid |
 316                                      use_signed_attrs),
 317                     "CMS_add1_signer");
 318                 ERR(CMS_final(cms, bm, NULL, CMS_NOCERTS | CMS_BINARY) < 0,
 319                     "CMS_final");
 320 
 321 #else
 322                 pkcs7 = PKCS7_sign(x509, private_key, NULL, bm,
 323                                    PKCS7_NOCERTS | PKCS7_BINARY |
 324                                    PKCS7_DETACHED | use_signed_attrs);
 325                 ERR(!pkcs7, "PKCS7_sign");
 326 #endif
 327 
 328                 if (save_sig) {
 329                         char *sig_file_name;
 330                         BIO *b;
 331 
 332                         ERR(asprintf(&sig_file_name, "%s.p7s", module_name) < 0,
 333                             "asprintf");
 334                         b = BIO_new_file(sig_file_name, "wb");
 335                         ERR(!b, "%s", sig_file_name);
 336 #ifndef USE_PKCS7
 337                         ERR(i2d_CMS_bio_stream(b, cms, NULL, 0) < 0,
 338                             "%s", sig_file_name);
 339 #else
 340                         ERR(i2d_PKCS7_bio(b, pkcs7) < 0,
 341                             "%s", sig_file_name);
 342 #endif
 343                         BIO_free(b);
 344                 }
 345 
 346                 if (sign_only) {
 347                         BIO_free(bm);
 348                         return 0;
 349                 }
 350         }
 351 
 352         /* Open the destination file now so that we can shovel the module data
 353          * across as we read it.
 354          */
 355         bd = BIO_new_file(dest_name, "wb");
 356         ERR(!bd, "%s", dest_name);
 357 
 358         /* Append the marker and the PKCS#7 message to the destination file */
 359         ERR(BIO_reset(bm) < 0, "%s", module_name);
 360         while ((n = BIO_read(bm, buf, sizeof(buf))),
 361                n > 0) {
 362                 ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
 363         }
 364         BIO_free(bm);
 365         ERR(n < 0, "%s", module_name);
 366         module_size = BIO_number_written(bd);
 367 
 368         if (!raw_sig) {
 369 #ifndef USE_PKCS7
 370                 ERR(i2d_CMS_bio_stream(bd, cms, NULL, 0) < 0, "%s", dest_name);
 371 #else
 372                 ERR(i2d_PKCS7_bio(bd, pkcs7) < 0, "%s", dest_name);
 373 #endif
 374         } else {
 375                 BIO *b;
 376 
 377                 /* Read the raw signature file and write the data to the
 378                  * destination file
 379                  */
 380                 b = BIO_new_file(raw_sig_name, "rb");
 381                 ERR(!b, "%s", raw_sig_name);
 382                 while ((n = BIO_read(b, buf, sizeof(buf))), n > 0)
 383                         ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
 384                 BIO_free(b);
 385         }
 386 
 387         sig_size = BIO_number_written(bd) - module_size;
 388         sig_info.sig_len = htonl(sig_size);
 389         ERR(BIO_write(bd, &sig_info, sizeof(sig_info)) < 0, "%s", dest_name);
 390         ERR(BIO_write(bd, magic_number, sizeof(magic_number) - 1) < 0, "%s", dest_name);
 391 
 392         ERR(BIO_free(bd) < 0, "%s", dest_name);
 393 
 394         /* Finally, if we're signing in place, replace the original. */
 395         if (replace_orig)
 396                 ERR(rename(dest_name, module_name) < 0, "%s", dest_name);
 397 
 398         return 0;
 399 }