webcit/crypto.c

   1 /* $Id$ */
   2
   3 #ifdef HAVE_OPENSSL
   4
   5
   6 #include <stdlib.h>
   7 #include <unistd.h>
   8 #include <string.h>
   9 #include <sys/stat.h>
  10 #include <sys/types.h>
  11 #include <pthread.h>
  12
  13 #include <sys/time.h>
  14 #include "webcit.h"
  15 #include "webserver.h"
  16
  17 #define CTDL_CRYPTO_DIR         "./keys"
  18 #define CTDL_KEY_PATH           CTDL_CRYPTO_DIR "/citadel.key"
  19 #define CTDL_CSR_PATH           CTDL_CRYPTO_DIR "/citadel.csr"
  20 #define CTDL_CER_PATH           CTDL_CRYPTO_DIR "/citadel.cer"
  21 #define SIGN_DAYS               365
  22
  23
  24 /* Shared Diffie-Hellman parameters */
  25 #define DH_P            "1A74527AEE4EE2568E85D4FB2E65E18C9394B9C80C42507D7A6A0DBE9A9A54B05A9A96800C34C7AA5297095B69C88901EEFD127F969DCA26A54C0E0B5C5473EBAEB00957D2633ECAE3835775425DE66C0DE6D024DBB17445E06E6B0C78415E589B8814F08531D02FD43778451E7685541079CFFB79EF0D26EFEEBBB69D1E80383"
  26 #define DH_G            "2"
  27 #define DH_L            1024
  28 #define CIT_CIPHERS     "ALL:RC4+RSA:+SSLv2:@STRENGTH"  /* see ciphers(1) */
  29
  30 SSL_CTX *ssl_ctx;               /* SSL context */
  31 pthread_mutex_t **SSLCritters;  /* Things needing locking */
  32
  33 pthread_key_t ThreadSSL;        /* Per-thread SSL context */
  34
  35 static unsigned long id_callback(void)
  36 {
  37         return (unsigned long) pthread_self();
  38 }
  39
  40  /*
  41   * Set up the cert things on the server side. We do need both the
  42   * private key (in key_file) and the cert (in cert_file).
  43   * Both files may be identical.
  44   *
  45   * This function is taken from OpenSSL apps/s_cb.c
  46   */
  47
  48 static int ctdl_install_certificate(SSL_CTX * ctx,
  49                           const char *cert_file, const char *key_file)
  50 {
  51         if (cert_file != NULL) {
  52                 if (SSL_CTX_use_certificate_file(ctx, cert_file,
  53                                                  SSL_FILETYPE_PEM) <= 0) {
  54                         lprintf(3, "unable to get certificate from '%s'",
  55                                 cert_file);
  56                         return (0);
  57                 }
  58                 if (key_file == NULL)
  59                         key_file = cert_file;
  60                 if (SSL_CTX_use_PrivateKey_file(ctx, key_file,
  61                                                 SSL_FILETYPE_PEM) <= 0) {
  62                         lprintf(3, "unable to get private key from '%s'",
  63                                 key_file);
  64                         return (0);
  65                 }
  66                 /* Now we know that a key and cert have been set against
  67                  * the SSL context */
  68                 if (!SSL_CTX_check_private_key(ctx)) {
  69                         lprintf(3,
  70                                 "Private key does not match the certificate public key");
  71                         return (0);
  72                 }
  73         }
  74         return (1);
  75 }
  76
  77
  78 void init_ssl(void)
  79 {
  80         SSL_METHOD *ssl_method;
  81         DH *dh;
  82         RSA *rsa=NULL;
  83         X509_REQ *req = NULL;
  84         X509 *cer = NULL;
  85         EVP_PKEY *pk = NULL;
  86         EVP_PKEY *req_pkey = NULL;
  87         X509_NAME *name = NULL;
  88         FILE *fp;
  89
  90         if (!access("/var/run/egd-pool", F_OK))
  91                 RAND_egd("/var/run/egd-pool");
  92
  93         if (!RAND_status()) {
  94                 lprintf(3,
  95                         "PRNG not adequately seeded, won't do SSL/TLS\n");
  96                 return;
  97         }
  98         SSLCritters =
  99             malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
 100         if (!SSLCritters) {
 101                 lprintf(1, "citserver: can't allocate memory!!\n");
 102                 /* Nothing's been initialized, just die */
 103                 exit(1);
 104         } else {
 105                 int a;
 106
 107                 for (a = 0; a < CRYPTO_num_locks(); a++) {
 108                         SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
 109                         if (!SSLCritters[a]) {
 110                                 lprintf(1,
 111                                         "citserver: can't allocate memory!!\n");
 112                                 /* Nothing's been initialized, just die */
 113                                 exit(1);
 114                         }
 115                         pthread_mutex_init(SSLCritters[a], NULL);
 116                 }
 117         }
 118
 119         /*
 120          * Initialize SSL transport layer
 121          */
 122         SSL_library_init();
 123         SSL_load_error_strings();
 124         ssl_method = SSLv23_server_method();
 125         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
 126                 lprintf(3, "SSL_CTX_new failed: %s\n",
 127                         ERR_reason_error_string(ERR_get_error()));
 128                 return;
 129         }
 130         if (!(SSL_CTX_set_cipher_list(ssl_ctx, CIT_CIPHERS))) {
 131                 lprintf(3, "SSL: No ciphers available\n");
 132                 SSL_CTX_free(ssl_ctx);
 133                 ssl_ctx = NULL;
 134                 return;
 135         }
 136 #if 0
 137 #if SSLEAY_VERSION_NUMBER >= 0x00906000L
 138         SSL_CTX_set_mode(ssl_ctx, SSL_CTX_get_mode(ssl_ctx) |
 139                          SSL_MODE_AUTO_RETRY);
 140 #endif
 141 #endif
 142
 143         CRYPTO_set_locking_callback(ssl_lock);
 144         CRYPTO_set_id_callback(id_callback);
 145
 146         /* Load DH parameters into the context */
 147         dh = DH_new();
 148         if (!dh) {
 149                 lprintf(3, "init_ssl() can't allocate a DH object: %s\n",
 150                         ERR_reason_error_string(ERR_get_error()));
 151                 SSL_CTX_free(ssl_ctx);
 152                 ssl_ctx = NULL;
 153                 return;
 154         }
 155         if (!(BN_hex2bn(&(dh->p), DH_P))) {
 156                 lprintf(3, "init_ssl() can't assign DH_P: %s\n",
 157                         ERR_reason_error_string(ERR_get_error()));
 158                 SSL_CTX_free(ssl_ctx);
 159                 ssl_ctx = NULL;
 160                 return;
 161         }
 162         if (!(BN_hex2bn(&(dh->g), DH_G))) {
 163                 lprintf(3, "init_ssl() can't assign DH_G: %s\n",
 164                         ERR_reason_error_string(ERR_get_error()));
 165                 SSL_CTX_free(ssl_ctx);
 166                 ssl_ctx = NULL;
 167                 return;
 168         }
 169         dh->length = DH_L;
 170         SSL_CTX_set_tmp_dh(ssl_ctx, dh);
 171         DH_free(dh);
 172
 173         /* Get our certificates in order.
 174          * First, create the key/cert directory if it's not there already...
 175          */
 176         mkdir(CTDL_CRYPTO_DIR, 0700);
 177
 178         /*
 179          * Generate a key pair if we don't have one.
 180          */
 181         if (access(CTDL_KEY_PATH, R_OK) != 0) {
 182                 lprintf(5, "Generating RSA key pair.\n");
 183                 rsa = RSA_generate_key(1024,    /* modulus size */
 184                                         65537,  /* exponent */
 185                                         NULL,   /* no callback */
 186                                         NULL);  /* no callback */
 187                 if (rsa == NULL) {
 188                         lprintf(3, "Key generation failed: %s\n",
 189                                 ERR_reason_error_string(ERR_get_error()));
 190                 }
 191                 if (rsa != NULL) {
 192                         fp = fopen(CTDL_KEY_PATH, "w");
 193                         if (fp != NULL) {
 194                                 chmod(CTDL_KEY_PATH, 0600);
 195                                 if (PEM_write_RSAPrivateKey(fp, /* the file */
 196                                                         rsa,    /* the key */
 197                                                         NULL,   /* no enc */
 198                                                         NULL,   /* no passphr */
 199                                                         0,      /* no passphr */
 200                                                         NULL,   /* no callbk */
 201                                                         NULL    /* no callbk */
 202                                 ) != 1) {
 203                                         lprintf(3, "Cannot write key: %s\n",
 204                                                 ERR_reason_error_string(ERR_get_error()));
 205                                         unlink(CTDL_KEY_PATH);
 206                                 }
 207                                 fclose(fp);
 208                         }
 209                         RSA_free(rsa);
 210                 }
 211         }
 212
 213         /*
 214          * Generate a CSR if we don't have one.
 215          */
 216         if (access(CTDL_CSR_PATH, R_OK) != 0) {
 217                 lprintf(5, "Generating a certificate signing request.\n");
 218
 219                 /*
 220                  * Read our key from the file.  No, we don't just keep this
 221                  * in memory from the above key-generation function, because
 222                  * there is the possibility that the key was already on disk
 223                  * and we didn't just generate it now.
 224                  */
 225                 fp = fopen(CTDL_KEY_PATH, "r");
 226                 if (fp) {
 227                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 228                         fclose(fp);
 229                 }
 230
 231                 if (rsa) {
 232
 233                         /* Create a public key from the private key */
 234                         if (pk=EVP_PKEY_new(), pk != NULL) {
 235                                 EVP_PKEY_assign_RSA(pk, rsa);
 236                                 if (req = X509_REQ_new(), req != NULL) {
 237
 238                                         /* Set the public key */
 239                                         X509_REQ_set_pubkey(req, pk);
 240                                         X509_REQ_set_version(req, 0L);
 241
 242                                         name = X509_REQ_get_subject_name(req);
 243
 244                                         /* Tell it who we are */
 245
 246                                         /*
 247                                         X509_NAME_add_entry_by_txt(name, "C",
 248                                                 MBSTRING_ASC, "US", -1, -1, 0);
 249
 250                                         X509_NAME_add_entry_by_txt(name, "ST",
 251                                                 MBSTRING_ASC, "New York", -1, -1, 0);
 252
 253                                         X509_NAME_add_entry_by_txt(name, "L",
 254                                                 MBSTRING_ASC, "Mount Kisco", -1, -1, 0);
 255                                         */
 256
 257                                         X509_NAME_add_entry_by_txt(name, "O",
 258                                                 MBSTRING_ASC, "FIXME.FIXME.org", -1, -1, 0);
 259
 260                                         X509_NAME_add_entry_by_txt(name, "OU",
 261                                                 MBSTRING_ASC, "Citadel server", -1, -1, 0);
 262
 263                                         X509_NAME_add_entry_by_txt(name, "CN",
 264                                                 MBSTRING_ASC, "FIXME.FIXME.org", -1, -1, 0);
 265
 266                                         X509_REQ_set_subject_name(req, name);
 267
 268                                         /* Sign the CSR */
 269                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 270                                                 lprintf(3, "X509_REQ_sign(): error\n");
 271                                         }
 272                                         else {
 273                                                 /* Write it to disk. */
 274                                                 fp = fopen(CTDL_CSR_PATH, "w");
 275                                                 if (fp != NULL) {
 276                                                         chmod(CTDL_CSR_PATH, 0600);
 277                                                         PEM_write_X509_REQ(fp, req);
 278                                                         fclose(fp);
 279                                                 }
 280                                         }
 281
 282                                         X509_REQ_free(req);
 283                                 }
 284                         }
 285
 286                         RSA_free(rsa);
 287                 }
 288
 289                 else {
 290                         lprintf(3, "Unable to read private key.\n");
 291                 }
 292         }
 293
 294
 295
 296         /*
 297          * Generate a self-signed certificate if we don't have one.
 298          */
 299         if (access(CTDL_CER_PATH, R_OK) != 0) {
 300                 lprintf(5, "Generating a self-signed certificate.\n");
 301
 302                 /* Same deal as before: always read the key from disk because
 303                  * it may or may not have just been generated.
 304                  */
 305                 fp = fopen(CTDL_KEY_PATH, "r");
 306                 if (fp) {
 307                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 308                         fclose(fp);
 309                 }
 310
 311                 /* This also holds true for the CSR. */
 312                 req = NULL;
 313                 cer = NULL;
 314                 pk = NULL;
 315                 if (rsa) {
 316                         if (pk=EVP_PKEY_new(), pk != NULL) {
 317                                 EVP_PKEY_assign_RSA(pk, rsa);
 318                         }
 319
 320                         fp = fopen(CTDL_CSR_PATH, "r");
 321                         if (fp) {
 322                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 323                                 fclose(fp);
 324                         }
 325
 326                         if (req) {
 327                                 if (cer = X509_new(), cer != NULL) {
 328
 329                                         X509_set_issuer_name(cer, req->req_info->subject);
 330                                         X509_set_subject_name(cer, req->req_info->subject);
 331                                         X509_gmtime_adj(X509_get_notBefore(cer),0);
 332                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 333                                         req_pkey = X509_REQ_get_pubkey(req);
 334                                         X509_set_pubkey(cer, req_pkey);
 335                                         EVP_PKEY_free(req_pkey);
 336
 337                                         /* Sign the cert */
 338                                         if (!X509_sign(cer, pk, EVP_md5())) {
 339                                                 lprintf(3, "X509_sign(): error\n");
 340                                         }
 341                                         else {
 342                                                 /* Write it to disk. */
 343                                                 fp = fopen(CTDL_CER_PATH, "w");
 344                                                 if (fp != NULL) {
 345                                                         chmod(CTDL_CER_PATH, 0600);
 346                                                         PEM_write_X509(fp, cer);
 347                                                         fclose(fp);
 348                                                 }
 349                                         }
 350                                         X509_free(cer);
 351                                 }
 352                         }
 353
 354                         RSA_free(rsa);
 355                 }
 356         }
 357
 358
 359         /*
 360          * Now try to bind to the key and certificate.
 361          */
 362         if (ctdl_install_certificate(ssl_ctx,
 363                         CTDL_CER_PATH,
 364                         CTDL_KEY_PATH) != 1)
 365         {
 366                 lprintf(3, "Cannot install certificate: %s\n",
 367                                 ERR_reason_error_string(ERR_get_error()));
 368         }
 369
 370 }
 371
 372
 373 /*
 374  * starttls() starts SSL/TLS encryption for the current session.
 375  */
 376 int starttls(int sock) {
 377         int retval, bits, alg_bits;
 378         SSL *newssl;
 379
 380         pthread_setspecific(ThreadSSL, NULL);
 381
 382         if (!ssl_ctx) {
 383                 return(1);
 384         }
 385         if (!(newssl = SSL_new(ssl_ctx))) {
 386                 lprintf(3, "SSL_new failed: %s\n",
 387                                 ERR_reason_error_string(ERR_get_error()));
 388                 return(2);
 389         }
 390         if (!(SSL_set_fd(newssl, sock))) {
 391                 lprintf(3, "SSL_set_fd failed: %s\n",
 392                         ERR_reason_error_string(ERR_get_error()));
 393                 SSL_free(newssl);
 394                 return(3);
 395         }
 396         retval = SSL_accept(newssl);
 397         if (retval < 1) {
 398                 /*
 399                  * Can't notify the client of an error here; they will
 400                  * discover the problem at the SSL layer and should
 401                  * revert to unencrypted communications.
 402                  */
 403                 long errval;
 404
 405                 errval = SSL_get_error(newssl, retval);
 406                 lprintf(3, "SSL_accept failed: %s\n",
 407                         ERR_reason_error_string(ERR_get_error()));
 408                 SSL_free(newssl);
 409                 newssl = NULL;
 410                 return(4);
 411         }
 412         BIO_set_close(newssl->rbio, BIO_NOCLOSE);
 413         bits =
 414             SSL_CIPHER_get_bits(SSL_get_current_cipher(newssl),
 415                                 &alg_bits);
 416         lprintf(5, "SSL/TLS using %s on %s (%d of %d bits)\n",
 417                 SSL_CIPHER_get_name(SSL_get_current_cipher(newssl)),
 418                 SSL_CIPHER_get_version(SSL_get_current_cipher(newssl)),
 419                 bits, alg_bits);
 420
 421         pthread_setspecific(ThreadSSL, newssl);
 422         return(0);
 423 }
 424
 425
 426
 427 /*
 428  * endtls() shuts down the TLS connection
 429  *
 430  * WARNING:  This may make your session vulnerable to a known plaintext
 431  * attack in the current implmentation.
 432  */
 433 void endtls(void)
 434 {
 435         lprintf(5, "Ending SSL/TLS\n");
 436         SSL_shutdown(THREADSSL);
 437         SSL_free(THREADSSL);
 438         pthread_setspecific(ThreadSSL, NULL);
 439 }
 440
 441
 442 /*
 443  * ssl_lock() callback for OpenSSL mutex locks
 444  */
 445 void ssl_lock(int mode, int n, const char *file, int line)
 446 {
 447         if (mode & CRYPTO_LOCK)
 448                 pthread_mutex_lock(SSLCritters[n]);
 449         else
 450                 pthread_mutex_unlock(SSLCritters[n]);
 451 }
 452
 453 /*
 454  * client_write_ssl() Send binary data to the client encrypted.
 455  */
 456 void client_write_ssl(char *buf, int nbytes)
 457 {
 458         int retval;
 459         int nremain;
 460         char junk[1];
 461
 462         nremain = nbytes;
 463
 464         while (nremain > 0) {
 465                 if (SSL_want_write(THREADSSL)) {
 466                         if ((SSL_read(THREADSSL, junk, 0)) < 1) {
 467                                 lprintf(9, "SSL_read in client_write: %s\n", ERR_reason_error_string(ERR_get_error()));
 468                         }
 469                 }
 470                 retval =
 471                     SSL_write(THREADSSL, &buf[nbytes - nremain], nremain);
 472                 if (retval < 1) {
 473                         long errval;
 474
 475                         errval = SSL_get_error(THREADSSL, retval);
 476                         if (errval == SSL_ERROR_WANT_READ ||
 477                             errval == SSL_ERROR_WANT_WRITE) {
 478                                 sleep(1);
 479                                 continue;
 480                         }
 481                         lprintf(9, "SSL_write got error %ld, ret %d\n", errval, retval);
 482                         if (retval == -1)
 483                                 lprintf(9, "errno is %d\n", errno);
 484                         endtls();
 485                         client_write(&buf[nbytes - nremain], nremain);
 486                         return;
 487                 }
 488                 nremain -= retval;
 489         }
 490 }
 491
 492
 493 /*
 494  * client_read_ssl() - read data from the encrypted layer.
 495  */
 496 int client_read_ssl(char *buf, int bytes, int timeout)
 497 {
 498 #if 0
 499         fd_set rfds;
 500         struct timeval tv;
 501         int retval;
 502         int s;
 503 #endif
 504         int len, rlen;
 505         char junk[1];
 506
 507         len = 0;
 508         while (len < bytes) {
 509 #if 0
 510                 /*
 511                  * This code is disabled because we don't need it when
 512                  * using blocking reads (which we are). -IO
 513                  */
 514                 FD_ZERO(&rfds);
 515                 s = BIO_get_fd(THREADSSL->rbio, NULL);
 516                 FD_SET(s, &rfds);
 517                 tv.tv_sec = timeout;
 518                 tv.tv_usec = 0;
 519
 520                 retval = select(s + 1, &rfds, NULL, NULL, &tv);
 521
 522                 if (FD_ISSET(s, &rfds) == 0) {
 523                         return (0);
 524                 }
 525
 526 #endif
 527                 if (SSL_want_read(THREADSSL)) {
 528                         if ((SSL_write(THREADSSL, junk, 0)) < 1) {
 529                                 lprintf(9, "SSL_write in client_read: %s\n", ERR_reason_error_string(ERR_get_error()));
 530                         }
 531                 }
 532                 rlen = SSL_read(THREADSSL, &buf[len], bytes - len);
 533                 if (rlen < 1) {
 534                         long errval;
 535
 536                         errval = SSL_get_error(THREADSSL, rlen);
 537                         if (errval == SSL_ERROR_WANT_READ ||
 538                             errval == SSL_ERROR_WANT_WRITE) {
 539                                 sleep(1);
 540                                 continue;
 541                         }
 542                         lprintf(9, "SSL_read got error %ld\n", errval);
 543                         endtls();
 544                         return (client_read_to
 545                                 (WC->http_sock, &buf[len], bytes - len, timeout));
 546                 }
 547                 len += rlen;
 548         }
 549         return (1);
 550 }
 551
 552
 553 #endif                          /* HAVE_OPENSSL */