scripts/sign-file.c

   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 OPENSSL_VERSION_NUMBER < 0x10000000L || defined(OPENSSL_NO_CMS)
  45 #define USE_PKCS7
  46 #endif
  47 #ifndef USE_PKCS7
  48 #include <openssl/cms.h>
  49 #else
  50 #include <openssl/pkcs7.h>
  51 #endif
  52
  53 struct module_signature {
  54         uint8_t         algo;           /* Public-key crypto algorithm [0] */
  55         uint8_t         hash;           /* Digest algorithm [0] */
  56         uint8_t         id_type;        /* Key identifier type [PKEY_ID_PKCS7] */
  57         uint8_t         signer_len;     /* Length of signer's name [0] */
  58         uint8_t         key_id_len;     /* Length of key identifier [0] */
  59         uint8_t         __pad[3];
  60         uint32_t        sig_len;        /* Length of signature data */
  61 };
  62
  63 #define PKEY_ID_PKCS7 2
  64
  65 static char magic_number[] = "~Module signature appended~\n";
  66
  67 static __attribute__((noreturn))
  68 void format(void)
  69 {
  70         fprintf(stderr,
  71                 "Usage: scripts/sign-file [-dp] <hash algo> <key> <x509> <module> [<dest>]\n");
  72         fprintf(stderr,
  73                 "       scripts/sign-file -s <raw sig> <hash algo> <x509> <module> [<dest>]\n");
  74         exit(2);
  75 }
  76
  77 static void display_openssl_errors(int l)
  78 {
  79         const char *file;
  80         char buf[120];
  81         int e, line;
  82
  83         if (ERR_peek_error() == 0)
  84                 return;
  85         fprintf(stderr, "At main.c:%d:\n", l);
  86
  87         while ((e = ERR_get_error_line(&file, &line))) {
  88                 ERR_error_string(e, buf);
  89                 fprintf(stderr, "- SSL %s: %s:%d\n", buf, file, line);
  90         }
  91 }
  92
  93 static void drain_openssl_errors(void)
  94 {
  95         const char *file;
  96         int line;
  97
  98         if (ERR_peek_error() == 0)
  99                 return;
 100         while (ERR_get_error_line(&file, &line)) {}
 101 }
 102
 103 #define ERR(cond, fmt, ...)                             \
 104         do {                                            \
 105                 bool __cond = (cond);                   \
 106                 display_openssl_errors(__LINE__);       \
 107                 if (__cond) {                           \
 108                         err(1, fmt, ## __VA_ARGS__);    \
 109                 }                                       \
 110         } while(0)
 111
 112 static const char *key_pass;
 113
 114 static int pem_pw_cb(char *buf, int len, int w, void *v)
 115 {
 116         int pwlen;
 117
 118         if (!key_pass)
 119                 return -1;
 120
 121         pwlen = strlen(key_pass);
 122         if (pwlen >= len)
 123                 return -1;
 124
 125         strcpy(buf, key_pass);
 126
 127         /* If it's wrong, don't keep trying it. */
 128         key_pass = NULL;
 129
 130         return pwlen;
 131 }
 132
 133 static EVP_PKEY *read_private_key(const char *private_key_name)
 134 {
 135         EVP_PKEY *private_key;
 136
 137         if (!strncmp(private_key_name, "pkcs11:", 7)) {
 138                 ENGINE *e;
 139
 140                 ENGINE_load_builtin_engines();
 141                 drain_openssl_errors();
 142                 e = ENGINE_by_id("pkcs11");
 143                 ERR(!e, "Load PKCS#11 ENGINE");
 144                 if (ENGINE_init(e))
 145                         drain_openssl_errors();
 146                 else
 147                         ERR(1, "ENGINE_init");
 148                 if (key_pass)
 149                         ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0),
 150                             "Set PKCS#11 PIN");
 151                 private_key = ENGINE_load_private_key(e, private_key_name,
 152                                                       NULL, NULL);
 153                 ERR(!private_key, "%s", private_key_name);
 154         } else {
 155                 BIO *b;
 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,
 160                                                       NULL);
 161                 ERR(!private_key, "%s", private_key_name);
 162                 BIO_free(b);
 163         }
 164
 165         return private_key;
 166 }
 167
 168 static X509 *read_x509(const char *x509_name)
 169 {
 170         unsigned char buf[2];
 171         X509 *x509;
 172         BIO *b;
 173         int n;
 174
 175         b = BIO_new_file(x509_name, "rb");
 176         ERR(!b, "%s", x509_name);
 177
 178         /* Look at the first two bytes of the file to determine the encoding */
 179         n = BIO_read(b, buf, 2);
 180         if (n != 2) {
 181                 if (BIO_should_retry(b)) {
 182                         fprintf(stderr, "%s: Read wanted retry\n", x509_name);
 183                         exit(1);
 184                 }
 185                 if (n >= 0) {
 186                         fprintf(stderr, "%s: Short read\n", x509_name);
 187                         exit(1);
 188                 }
 189                 ERR(1, "%s", x509_name);
 190         }
 191
 192         ERR(BIO_reset(b) != 0, "%s", x509_name);
 193
 194         if (buf[0] == 0x30 && buf[1] >= 0x81 && buf[1] <= 0x84)
 195                 /* Assume raw DER encoded X.509 */
 196                 x509 = d2i_X509_bio(b, NULL);
 197         else
 198                 /* Assume PEM encoded X.509 */
 199                 x509 = PEM_read_bio_X509(b, NULL, NULL, NULL);
 200
 201         BIO_free(b);
 202         ERR(!x509, "%s", x509_name);
 203
 204         return x509;
 205 }
 206
 207 int main(int argc, char **argv)
 208 {
 209         struct module_signature sig_info = { .id_type = PKEY_ID_PKCS7 };
 210         char *hash_algo = NULL;
 211         char *private_key_name = NULL, *raw_sig_name = NULL;
 212         char *x509_name, *module_name, *dest_name;
 213         bool save_sig = false, replace_orig;
 214         bool sign_only = false;
 215         bool raw_sig = false;
 216         unsigned char buf[4096];
 217         unsigned long module_size, sig_size;
 218         unsigned int use_signed_attrs;
 219         const EVP_MD *digest_algo;
 220         EVP_PKEY *private_key;
 221 #ifndef USE_PKCS7
 222         CMS_ContentInfo *cms = NULL;
 223         unsigned int use_keyid = 0;
 224 #else
 225         PKCS7 *pkcs7 = NULL;
 226 #endif
 227         X509 *x509;
 228         BIO *bd, *bm;
 229         int opt, n;
 230         OpenSSL_add_all_algorithms();
 231         ERR_load_crypto_strings();
 232         ERR_clear_error();
 233
 234         key_pass = getenv("KBUILD_SIGN_PIN");
 235
 236 #ifndef USE_PKCS7
 237         use_signed_attrs = CMS_NOATTR;
 238 #else
 239         use_signed_attrs = PKCS7_NOATTR;
 240 #endif
 241
 242         do {
 243                 opt = getopt(argc, argv, "sdpk");
 244                 switch (opt) {
 245                 case 's': raw_sig = true; break;
 246                 case 'p': save_sig = true; break;
 247                 case 'd': sign_only = true; save_sig = true; break;
 248 #ifndef USE_PKCS7
 249                 case 'k': use_keyid = CMS_USE_KEYID; break;
 250 #endif
 251                 case -1: break;
 252                 default: format();
 253                 }
 254         } while (opt != -1);
 255
 256         argc -= optind;
 257         argv += optind;
 258         if (argc < 4 || argc > 5)
 259                 format();
 260
 261         if (raw_sig) {
 262                 raw_sig_name = argv[0];
 263                 hash_algo = argv[1];
 264         } else {
 265                 hash_algo = argv[0];
 266                 private_key_name = argv[1];
 267         }
 268         x509_name = argv[2];
 269         module_name = argv[3];
 270         if (argc == 5) {
 271                 dest_name = argv[4];
 272                 replace_orig = false;
 273         } else {
 274                 ERR(asprintf(&dest_name, "%s.~signed~", module_name) < 0,
 275                     "asprintf");
 276                 replace_orig = true;
 277         }
 278
 279 #ifdef USE_PKCS7
 280         if (strcmp(hash_algo, "sha1") != 0) {
 281                 fprintf(stderr, "sign-file: %s only supports SHA1 signing\n",
 282                         OPENSSL_VERSION_TEXT);
 283                 exit(3);
 284         }
 285 #endif
 286
 287         /* Open the module file */
 288         bm = BIO_new_file(module_name, "rb");
 289         ERR(!bm, "%s", module_name);
 290
 291         if (!raw_sig) {
 292                 /* Read the private key and the X.509 cert the PKCS#7 message
 293                  * will point to.
 294                  */
 295                 private_key = read_private_key(private_key_name);
 296                 x509 = read_x509(x509_name);
 297
 298                 /* Digest the module data. */
 299                 OpenSSL_add_all_digests();
 300                 display_openssl_errors(__LINE__);
 301                 digest_algo = EVP_get_digestbyname(hash_algo);
 302                 ERR(!digest_algo, "EVP_get_digestbyname");
 303
 304 #ifndef USE_PKCS7
 305                 /* Load the signature message from the digest buffer. */
 306                 cms = CMS_sign(NULL, NULL, NULL, NULL,
 307                                CMS_NOCERTS | CMS_PARTIAL | CMS_BINARY |
 308                                CMS_DETACHED | CMS_STREAM);
 309                 ERR(!cms, "CMS_sign");
 310
 311                 ERR(!CMS_add1_signer(cms, x509, private_key, digest_algo,
 312                                      CMS_NOCERTS | CMS_BINARY |
 313                                      CMS_NOSMIMECAP | use_keyid |
 314                                      use_signed_attrs),
 315                     "CMS_add1_signer");
 316                 ERR(CMS_final(cms, bm, NULL, CMS_NOCERTS | CMS_BINARY) < 0,
 317                     "CMS_final");
 318
 319 #else
 320                 pkcs7 = PKCS7_sign(x509, private_key, NULL, bm,
 321                                    PKCS7_NOCERTS | PKCS7_BINARY |
 322                                    PKCS7_DETACHED | use_signed_attrs);
 323                 ERR(!pkcs7, "PKCS7_sign");
 324 #endif
 325
 326                 if (save_sig) {
 327                         char *sig_file_name;
 328                         BIO *b;
 329
 330                         ERR(asprintf(&sig_file_name, "%s.p7s", module_name) < 0,
 331                             "asprintf");
 332                         b = BIO_new_file(sig_file_name, "wb");
 333                         ERR(!b, "%s", sig_file_name);
 334 #ifndef USE_PKCS7
 335                         ERR(i2d_CMS_bio_stream(b, cms, NULL, 0) < 0,
 336                             "%s", sig_file_name);
 337 #else
 338                         ERR(i2d_PKCS7_bio(b, pkcs7) < 0,
 339                             "%s", sig_file_name);
 340 #endif
 341                         BIO_free(b);
 342                 }
 343
 344                 if (sign_only) {
 345                         BIO_free(bm);
 346                         return 0;
 347                 }
 348         }
 349
 350         /* Open the destination file now so that we can shovel the module data
 351          * across as we read it.
 352          */
 353         bd = BIO_new_file(dest_name, "wb");
 354         ERR(!bd, "%s", dest_name);
 355
 356         /* Append the marker and the PKCS#7 message to the destination file */
 357         ERR(BIO_reset(bm) < 0, "%s", module_name);
 358         while ((n = BIO_read(bm, buf, sizeof(buf))),
 359                n > 0) {
 360                 ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
 361         }
 362         BIO_free(bm);
 363         ERR(n < 0, "%s", module_name);
 364         module_size = BIO_number_written(bd);
 365
 366         if (!raw_sig) {
 367 #ifndef USE_PKCS7
 368                 ERR(i2d_CMS_bio_stream(bd, cms, NULL, 0) < 0, "%s", dest_name);
 369 #else
 370                 ERR(i2d_PKCS7_bio(bd, pkcs7) < 0, "%s", dest_name);
 371 #endif
 372         } else {
 373                 BIO *b;
 374
 375                 /* Read the raw signature file and write the data to the
 376                  * destination file
 377                  */
 378                 b = BIO_new_file(raw_sig_name, "rb");
 379                 ERR(!b, "%s", raw_sig_name);
 380                 while ((n = BIO_read(b, buf, sizeof(buf))), n > 0)
 381                         ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
 382                 BIO_free(b);
 383         }
 384
 385         sig_size = BIO_number_written(bd) - module_size;
 386         sig_info.sig_len = htonl(sig_size);
 387         ERR(BIO_write(bd, &sig_info, sizeof(sig_info)) < 0, "%s", dest_name);
 388         ERR(BIO_write(bd, magic_number, sizeof(magic_number) - 1) < 0, "%s", dest_name);
 389
 390         ERR(BIO_free(bd) < 0, "%s", dest_name);
 391
 392         /* Finally, if we're signing in place, replace the original. */
 393         if (replace_orig)
 394                 ERR(rename(dest_name, module_name) < 0, "%s", dest_name);
 395
 396         return 0;
 397 }