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/opensslv.h>
  24 #include <openssl/bio.h>
  25 #include <openssl/evp.h>
  26 #include <openssl/pem.h>
  27 #include <openssl/err.h>
  28 #include <openssl/engine.h>
  29
  30 /*
  31  * Use CMS if we have openssl-1.0.0 or newer available - otherwise we have to
  32  * assume that it's not available and its header file is missing and that we
  33  * should use PKCS#7 instead.  Switching to the older PKCS#7 format restricts
  34  * the options we have on specifying the X.509 certificate we want.
  35  *
  36  * Further, older versions of OpenSSL don't support manually adding signers to
  37  * the PKCS#7 message so have to accept that we get a certificate included in
  38  * the signature message.  Nor do such older versions of OpenSSL support
  39  * signing with anything other than SHA1 - so we're stuck with that if such is
  40  * the case.
  41  */
  42 #if OPENSSL_VERSION_NUMBER < 0x10000000L
  43 #define USE_PKCS7
  44 #endif
  45 #ifndef USE_PKCS7
  46 #include <openssl/cms.h>
  47 #else
  48 #include <openssl/pkcs7.h>
  49 #endif
  50
  51 struct module_signature {
  52         uint8_t         algo;           /* Public-key crypto algorithm [0] */
  53         uint8_t         hash;           /* Digest algorithm [0] */
  54         uint8_t         id_type;        /* Key identifier type [PKEY_ID_PKCS7] */
  55         uint8_t         signer_len;     /* Length of signer's name [0] */
  56         uint8_t         key_id_len;     /* Length of key identifier [0] */
  57         uint8_t         __pad[3];
  58         uint32_t        sig_len;        /* Length of signature data */
  59 };
  60
  61 #define PKEY_ID_PKCS7 2
  62
  63 static char magic_number[] = "~Module signature appended~\n";
  64
  65 static __attribute__((noreturn))
  66 void format(void)
  67 {
  68         fprintf(stderr,
  69                 "Usage: scripts/sign-file [-dp] <hash algo> <key> <x509> <module> [<dest>]\n");
  70         exit(2);
  71 }
  72
  73 static void display_openssl_errors(int l)
  74 {
  75         const char *file;
  76         char buf[120];
  77         int e, line;
  78
  79         if (ERR_peek_error() == 0)
  80                 return;
  81         fprintf(stderr, "At main.c:%d:\n", l);
  82
  83         while ((e = ERR_get_error_line(&file, &line))) {
  84                 ERR_error_string(e, buf);
  85                 fprintf(stderr, "- SSL %s: %s:%d\n", buf, file, line);
  86         }
  87 }
  88
  89 static void drain_openssl_errors(void)
  90 {
  91         const char *file;
  92         int line;
  93
  94         if (ERR_peek_error() == 0)
  95                 return;
  96         while (ERR_get_error_line(&file, &line)) {}
  97 }
  98
  99 #define ERR(cond, fmt, ...)                             \
 100         do {                                            \
 101                 bool __cond = (cond);                   \
 102                 display_openssl_errors(__LINE__);       \
 103                 if (__cond) {                           \
 104                         err(1, fmt, ## __VA_ARGS__);    \
 105                 }                                       \
 106         } while(0)
 107
 108 static const char *key_pass;
 109
 110 static int pem_pw_cb(char *buf, int len, int w, void *v)
 111 {
 112         int pwlen;
 113
 114         if (!key_pass)
 115                 return -1;
 116
 117         pwlen = strlen(key_pass);
 118         if (pwlen >= len)
 119                 return -1;
 120
 121         strcpy(buf, key_pass);
 122
 123         /* If it's wrong, don't keep trying it. */
 124         key_pass = NULL;
 125
 126         return pwlen;
 127 }
 128
 129 int main(int argc, char **argv)
 130 {
 131         struct module_signature sig_info = { .id_type = PKEY_ID_PKCS7 };
 132         char *hash_algo = NULL;
 133         char *private_key_name, *x509_name, *module_name, *dest_name;
 134         bool save_sig = false, replace_orig;
 135         bool sign_only = false;
 136         unsigned char buf[4096];
 137         unsigned long module_size, sig_size;
 138         unsigned int use_signed_attrs;
 139         const EVP_MD *digest_algo;
 140         EVP_PKEY *private_key;
 141 #ifndef USE_PKCS7
 142         CMS_ContentInfo *cms;
 143         unsigned int use_keyid = 0;
 144 #else
 145         PKCS7 *pkcs7;
 146 #endif
 147         X509 *x509;
 148         BIO *b, *bd = NULL, *bm;
 149         int opt, n;
 150         OpenSSL_add_all_algorithms();
 151         ERR_load_crypto_strings();
 152         ERR_clear_error();
 153
 154         key_pass = getenv("KBUILD_SIGN_PIN");
 155
 156 #ifndef USE_PKCS7
 157         use_signed_attrs = CMS_NOATTR;
 158 #else
 159         use_signed_attrs = PKCS7_NOATTR;
 160 #endif
 161
 162         do {
 163                 opt = getopt(argc, argv, "dpk");
 164                 switch (opt) {
 165                 case 'p': save_sig = true; break;
 166                 case 'd': sign_only = true; save_sig = true; break;
 167 #ifndef USE_PKCS7
 168                 case 'k': use_keyid = CMS_USE_KEYID; break;
 169 #endif
 170                 case -1: break;
 171                 default: format();
 172                 }
 173         } while (opt != -1);
 174
 175         argc -= optind;
 176         argv += optind;
 177         if (argc < 4 || argc > 5)
 178                 format();
 179
 180         hash_algo = argv[0];
 181         private_key_name = argv[1];
 182         x509_name = argv[2];
 183         module_name = argv[3];
 184         if (argc == 5) {
 185                 dest_name = argv[4];
 186                 replace_orig = false;
 187         } else {
 188                 ERR(asprintf(&dest_name, "%s.~signed~", module_name) < 0,
 189                     "asprintf");
 190                 replace_orig = true;
 191         }
 192
 193 #ifdef USE_PKCS7
 194         if (strcmp(hash_algo, "sha1") != 0) {
 195                 fprintf(stderr, "sign-file: %s only supports SHA1 signing\n",
 196                         OPENSSL_VERSION_TEXT);
 197                 exit(3);
 198         }
 199 #endif
 200
 201         /* Read the private key and the X.509 cert the PKCS#7 message
 202          * will point to.
 203          */
 204         if (!strncmp(private_key_name, "pkcs11:", 7)) {
 205                 ENGINE *e;
 206
 207                 ENGINE_load_builtin_engines();
 208                 drain_openssl_errors();
 209                 e = ENGINE_by_id("pkcs11");
 210                 ERR(!e, "Load PKCS#11 ENGINE");
 211                 if (ENGINE_init(e))
 212                         drain_openssl_errors();
 213                 else
 214                         ERR(1, "ENGINE_init");
 215                 if (key_pass)
 216                         ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0), "Set PKCS#11 PIN");
 217                 private_key = ENGINE_load_private_key(e, private_key_name, NULL,
 218                                                       NULL);
 219                 ERR(!private_key, "%s", private_key_name);
 220         } else {
 221                 b = BIO_new_file(private_key_name, "rb");
 222                 ERR(!b, "%s", private_key_name);
 223                 private_key = PEM_read_bio_PrivateKey(b, NULL, pem_pw_cb, NULL);
 224                 ERR(!private_key, "%s", private_key_name);
 225                 BIO_free(b);
 226         }
 227
 228         b = BIO_new_file(x509_name, "rb");
 229         ERR(!b, "%s", x509_name);
 230         x509 = d2i_X509_bio(b, NULL); /* Binary encoded X.509 */
 231         if (!x509) {
 232                 ERR(BIO_reset(b) != 1, "%s", x509_name);
 233                 x509 = PEM_read_bio_X509(b, NULL, NULL, NULL); /* PEM encoded X.509 */
 234                 if (x509)
 235                         drain_openssl_errors();
 236         }
 237         BIO_free(b);
 238         ERR(!x509, "%s", x509_name);
 239
 240         /* Open the destination file now so that we can shovel the module data
 241          * across as we read it.
 242          */
 243         if (!sign_only) {
 244                 bd = BIO_new_file(dest_name, "wb");
 245                 ERR(!bd, "%s", dest_name);
 246         }
 247
 248         /* Digest the module data. */
 249         OpenSSL_add_all_digests();
 250         display_openssl_errors(__LINE__);
 251         digest_algo = EVP_get_digestbyname(hash_algo);
 252         ERR(!digest_algo, "EVP_get_digestbyname");
 253
 254         bm = BIO_new_file(module_name, "rb");
 255         ERR(!bm, "%s", module_name);
 256
 257 #ifndef USE_PKCS7
 258         /* Load the signature message from the digest buffer. */
 259         cms = CMS_sign(NULL, NULL, NULL, NULL,
 260                        CMS_NOCERTS | CMS_PARTIAL | CMS_BINARY | CMS_DETACHED | CMS_STREAM);
 261         ERR(!cms, "CMS_sign");
 262
 263         ERR(!CMS_add1_signer(cms, x509, private_key, digest_algo,
 264                              CMS_NOCERTS | CMS_BINARY | CMS_NOSMIMECAP |
 265                              use_keyid | use_signed_attrs),
 266             "CMS_add1_signer");
 267         ERR(CMS_final(cms, bm, NULL, CMS_NOCERTS | CMS_BINARY) < 0,
 268             "CMS_final");
 269
 270 #else
 271         pkcs7 = PKCS7_sign(x509, private_key, NULL, bm,
 272                            PKCS7_NOCERTS | PKCS7_BINARY |
 273                            PKCS7_DETACHED | use_signed_attrs);
 274         ERR(!pkcs7, "PKCS7_sign");
 275 #endif
 276
 277         if (save_sig) {
 278                 char *sig_file_name;
 279
 280                 ERR(asprintf(&sig_file_name, "%s.p7s", module_name) < 0,
 281                     "asprintf");
 282                 b = BIO_new_file(sig_file_name, "wb");
 283                 ERR(!b, "%s", sig_file_name);
 284 #ifndef USE_PKCS7
 285                 ERR(i2d_CMS_bio_stream(b, cms, NULL, 0) < 0,
 286                     "%s", sig_file_name);
 287 #else
 288                 ERR(i2d_PKCS7_bio(b, pkcs7) < 0,
 289                         "%s", sig_file_name);
 290 #endif
 291                 BIO_free(b);
 292         }
 293
 294         if (sign_only)
 295                 return 0;
 296
 297         /* Append the marker and the PKCS#7 message to the destination file */
 298         ERR(BIO_reset(bm) < 0, "%s", module_name);
 299         while ((n = BIO_read(bm, buf, sizeof(buf))),
 300                n > 0) {
 301                 ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
 302         }
 303         ERR(n < 0, "%s", module_name);
 304         module_size = BIO_number_written(bd);
 305
 306 #ifndef USE_PKCS7
 307         ERR(i2d_CMS_bio_stream(bd, cms, NULL, 0) < 0, "%s", dest_name);
 308 #else
 309         ERR(i2d_PKCS7_bio(bd, pkcs7) < 0, "%s", dest_name);
 310 #endif
 311         sig_size = BIO_number_written(bd) - module_size;
 312         sig_info.sig_len = htonl(sig_size);
 313         ERR(BIO_write(bd, &sig_info, sizeof(sig_info)) < 0, "%s", dest_name);
 314         ERR(BIO_write(bd, magic_number, sizeof(magic_number) - 1) < 0, "%s", dest_name);
 315
 316         ERR(BIO_free(bd) < 0, "%s", dest_name);
 317
 318         /* Finally, if we're signing in place, replace the original. */
 319         if (replace_orig)
 320                 ERR(rename(dest_name, module_name) < 0, "%s", dest_name);
 321
 322         return 0;
 323 }