citadel/serv_crypto.c

   1 /* $Id$ */
   2
   3 #include <string.h>
   4 #include <unistd.h>
   5 #include <sys/stat.h>
   6 #include <sys/types.h>
   7 #include "sysdep.h"
   8
   9 #ifdef HAVE_OPENSSL
  10 #include <openssl/ssl.h>
  11 #include <openssl/err.h>
  12 #include <openssl/rand.h>
  13 #endif
  14
  15 #if TIME_WITH_SYS_TIME
  16 # include <sys/time.h>
  17 # include <time.h>
  18 #else
  19 # if HAVE_SYS_TIME_H
  20 #  include <sys/time.h>
  21 # else
  22 #  include <time.h>
  23 # endif
  24 #endif
  25
  26 #ifdef HAVE_PTHREAD_H
  27 #include <pthread.h>
  28 #endif
  29
  30 #ifdef HAVE_SYS_SELECT_H
  31 #include <sys/select.h>
  32 #endif
  33
  34 #include <stdio.h>
  35 #include "server.h"
  36 #include "serv_crypto.h"
  37 #include "sysdep_decls.h"
  38 #include "serv_extensions.h"
  39 #include "citadel.h"
  40 #include "config.h"
  41
  42
  43 #ifdef HAVE_OPENSSL
  44 SSL_CTX *ssl_ctx;               /* SSL context */
  45 pthread_mutex_t **SSLCritters;  /* Things needing locking */
  46
  47 static unsigned long id_callback(void)
  48 {
  49         return (unsigned long) pthread_self();
  50 }
  51
  52  /*
  53   * Set up the cert things on the server side. We do need both the
  54   * private key (in key_file) and the cert (in cert_file).
  55   * Both files may be identical.
  56   *
  57   * This function is taken from OpenSSL apps/s_cb.c
  58   */
  59
  60 static int ctdl_install_certificate(SSL_CTX * ctx,
  61                           const char *cert_file, const char *key_file)
  62 {
  63         if (cert_file != NULL) {
  64                 if (SSL_CTX_use_certificate_file(ctx, cert_file,
  65                                                  SSL_FILETYPE_PEM) <= 0) {
  66                         lprintf(CTDL_CRIT, "unable to get certificate from '%s'",
  67                                 cert_file);
  68                         return (0);
  69                 }
  70                 if (key_file == NULL)
  71                         key_file = cert_file;
  72                 if (SSL_CTX_use_PrivateKey_file(ctx, key_file,
  73                                                 SSL_FILETYPE_PEM) <= 0) {
  74                         lprintf(CTDL_CRIT, "unable to get private key from '%s'",
  75                                 key_file);
  76                         return (0);
  77                 }
  78                 /* Now we know that a key and cert have been set against
  79                  * the SSL context */
  80                 if (!SSL_CTX_check_private_key(ctx)) {
  81                         lprintf(CTDL_CRIT,
  82                                 "Private key does not match the certificate public key");
  83                         return (0);
  84                 }
  85         }
  86         return (1);
  87 }
  88
  89
  90 void init_ssl(void)
  91 {
  92         SSL_METHOD *ssl_method;
  93         DH *dh;
  94         RSA *rsa=NULL;
  95         X509_REQ *req = NULL;
  96         X509 *cer = NULL;
  97         EVP_PKEY *pk = NULL;
  98         EVP_PKEY *req_pkey = NULL;
  99         X509_NAME *name = NULL;
 100         FILE *fp;
 101
 102         if (!access("/var/run/egd-pool", F_OK))
 103                 RAND_egd("/var/run/egd-pool");
 104
 105         if (!RAND_status()) {
 106                 lprintf(CTDL_CRIT,
 107                         "PRNG not adequately seeded, won't do SSL/TLS\n");
 108                 return;
 109         }
 110         SSLCritters =
 111             mallok(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
 112         if (!SSLCritters) {
 113                 lprintf(CTDL_EMERG, "citserver: can't allocate memory!!\n");
 114                 /* Nothing's been initialized, just die */
 115                 exit(1);
 116         } else {
 117                 int a;
 118
 119                 for (a = 0; a < CRYPTO_num_locks(); a++) {
 120                         SSLCritters[a] = mallok(sizeof(pthread_mutex_t));
 121                         if (!SSLCritters[a]) {
 122                                 lprintf(CTDL_EMERG,
 123                                         "citserver: can't allocate memory!!\n");
 124                                 /* Nothing's been initialized, just die */
 125                                 exit(1);
 126                         }
 127                         pthread_mutex_init(SSLCritters[a], NULL);
 128                 }
 129         }
 130
 131         /*
 132          * Initialize SSL transport layer
 133          */
 134         SSL_library_init();
 135         SSL_load_error_strings();
 136         ssl_method = SSLv23_server_method();
 137         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
 138                 lprintf(CTDL_CRIT, "SSL_CTX_new failed: %s\n",
 139                         ERR_reason_error_string(ERR_get_error()));
 140                 return;
 141         }
 142         if (!(SSL_CTX_set_cipher_list(ssl_ctx, CIT_CIPHERS))) {
 143                 lprintf(CTDL_CRIT, "SSL: No ciphers available\n");
 144                 SSL_CTX_free(ssl_ctx);
 145                 ssl_ctx = NULL;
 146                 return;
 147         }
 148 #if 0
 149 #if SSLEAY_VERSION_NUMBER >= 0x00906000L
 150         SSL_CTX_set_mode(ssl_ctx, SSL_CTX_get_mode(ssl_ctx) |
 151                          SSL_MODE_AUTO_RETRY);
 152 #endif
 153 #endif
 154
 155         CRYPTO_set_locking_callback(ssl_lock);
 156         CRYPTO_set_id_callback(id_callback);
 157
 158         /* Load DH parameters into the context */
 159         dh = DH_new();
 160         if (!dh) {
 161                 lprintf(CTDL_CRIT, "init_ssl() can't allocate a DH object: %s\n",
 162                         ERR_reason_error_string(ERR_get_error()));
 163                 SSL_CTX_free(ssl_ctx);
 164                 ssl_ctx = NULL;
 165                 return;
 166         }
 167         if (!(BN_hex2bn(&(dh->p), DH_P))) {
 168                 lprintf(CTDL_CRIT, "init_ssl() can't assign DH_P: %s\n",
 169                         ERR_reason_error_string(ERR_get_error()));
 170                 SSL_CTX_free(ssl_ctx);
 171                 ssl_ctx = NULL;
 172                 return;
 173         }
 174         if (!(BN_hex2bn(&(dh->g), DH_G))) {
 175                 lprintf(CTDL_CRIT, "init_ssl() can't assign DH_G: %s\n",
 176                         ERR_reason_error_string(ERR_get_error()));
 177                 SSL_CTX_free(ssl_ctx);
 178                 ssl_ctx = NULL;
 179                 return;
 180         }
 181         dh->length = DH_L;
 182         SSL_CTX_set_tmp_dh(ssl_ctx, dh);
 183         DH_free(dh);
 184
 185         /* Get our certificates in order.
 186          * First, create the key/cert directory if it's not there already...
 187          */
 188         mkdir(CTDL_CRYPTO_DIR, 0700);
 189
 190         /*
 191          * Generate a key pair if we don't have one.
 192          */
 193         if (access(CTDL_KEY_PATH, R_OK) != 0) {
 194                 lprintf(CTDL_INFO, "Generating RSA key pair.\n");
 195                 rsa = RSA_generate_key(1024,    /* modulus size */
 196                                         65537,  /* exponent */
 197                                         NULL,   /* no callback */
 198                                         NULL);  /* no callback */
 199                 if (rsa == NULL) {
 200                         lprintf(CTDL_CRIT, "Key generation failed: %s\n",
 201                                 ERR_reason_error_string(ERR_get_error()));
 202                 }
 203                 if (rsa != NULL) {
 204                         fp = fopen(CTDL_KEY_PATH, "w");
 205                         if (fp != NULL) {
 206                                 chmod(CTDL_KEY_PATH, 0600);
 207                                 if (PEM_write_RSAPrivateKey(fp, /* the file */
 208                                                         rsa,    /* the key */
 209                                                         NULL,   /* no enc */
 210                                                         NULL,   /* no passphr */
 211                                                         0,      /* no passphr */
 212                                                         NULL,   /* no callbk */
 213                                                         NULL    /* no callbk */
 214                                 ) != 1) {
 215                                         lprintf(CTDL_CRIT, "Cannot write key: %s\n",
 216                                                 ERR_reason_error_string(ERR_get_error()));
 217                                         unlink(CTDL_KEY_PATH);
 218                                 }
 219                                 fclose(fp);
 220                         }
 221                         RSA_free(rsa);
 222                 }
 223         }
 224
 225         /*
 226          * Generate a CSR if we don't have one.
 227          */
 228         if (access(CTDL_CSR_PATH, R_OK) != 0) {
 229                 lprintf(CTDL_INFO, "Generating a certificate signing request.\n");
 230
 231                 /*
 232                  * Read our key from the file.  No, we don't just keep this
 233                  * in memory from the above key-generation function, because
 234                  * there is the possibility that the key was already on disk
 235                  * and we didn't just generate it now.
 236                  */
 237                 fp = fopen(CTDL_KEY_PATH, "r");
 238                 if (fp) {
 239                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 240                         fclose(fp);
 241                 }
 242
 243                 if (rsa) {
 244
 245                         /* Create a public key from the private key */
 246                         if (pk=EVP_PKEY_new(), pk != NULL) {
 247                                 EVP_PKEY_assign_RSA(pk, rsa);
 248                                 if (req = X509_REQ_new(), req != NULL) {
 249
 250                                         /* Set the public key */
 251                                         X509_REQ_set_pubkey(req, pk);
 252                                         X509_REQ_set_version(req, 0L);
 253
 254                                         name = X509_REQ_get_subject_name(req);
 255
 256                                         /* Tell it who we are */
 257
 258                                         /*
 259                                         X509_NAME_add_entry_by_txt(name, "C",
 260                                                 MBSTRING_ASC, "US", -1, -1, 0);
 261
 262                                         X509_NAME_add_entry_by_txt(name, "ST",
 263                                                 MBSTRING_ASC, "New York", -1, -1, 0);
 264
 265                                         X509_NAME_add_entry_by_txt(name, "L",
 266                                                 MBSTRING_ASC, "Mount Kisco", -1, -1, 0);
 267                                         */
 268
 269                                         X509_NAME_add_entry_by_txt(name, "O",
 270                                                 MBSTRING_ASC, config.c_humannode, -1, -1, 0);
 271
 272                                         X509_NAME_add_entry_by_txt(name, "OU",
 273                                                 MBSTRING_ASC, "Citadel server", -1, -1, 0);
 274
 275                                         X509_NAME_add_entry_by_txt(name, "CN",
 276                                                 MBSTRING_ASC, config.c_fqdn, -1, -1, 0);
 277
 278                                         X509_REQ_set_subject_name(req, name);
 279
 280                                         /* Sign the CSR */
 281                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 282                                                 lprintf(CTDL_CRIT, "X509_REQ_sign(): error\n");
 283                                         }
 284                                         else {
 285                                                 /* Write it to disk. */
 286                                                 fp = fopen(CTDL_CSR_PATH, "w");
 287                                                 if (fp != NULL) {
 288                                                         chmod(CTDL_CSR_PATH, 0600);
 289                                                         PEM_write_X509_REQ(fp, req);
 290                                                         fclose(fp);
 291                                                 }
 292                                         }
 293
 294                                         X509_REQ_free(req);
 295                                 }
 296                         }
 297
 298                         RSA_free(rsa);
 299                 }
 300
 301                 else {
 302                         lprintf(CTDL_CRIT, "Unable to read private key.\n");
 303                 }
 304         }
 305
 306
 307
 308         /*
 309          * Generate a self-signed certificate if we don't have one.
 310          */
 311         if (access(CTDL_CER_PATH, R_OK) != 0) {
 312                 lprintf(CTDL_INFO, "Generating a self-signed certificate.\n");
 313
 314                 /* Same deal as before: always read the key from disk because
 315                  * it may or may not have just been generated.
 316                  */
 317                 fp = fopen(CTDL_KEY_PATH, "r");
 318                 if (fp) {
 319                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 320                         fclose(fp);
 321                 }
 322
 323                 /* This also holds true for the CSR. */
 324                 req = NULL;
 325                 cer = NULL;
 326                 pk = NULL;
 327                 if (rsa) {
 328                         if (pk=EVP_PKEY_new(), pk != NULL) {
 329                                 EVP_PKEY_assign_RSA(pk, rsa);
 330                         }
 331
 332                         fp = fopen(CTDL_CSR_PATH, "r");
 333                         if (fp) {
 334                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 335                                 fclose(fp);
 336                         }
 337
 338                         if (req) {
 339                                 if (cer = X509_new(), cer != NULL) {
 340
 341                                         X509_set_issuer_name(cer, req->req_info->subject);
 342                                         X509_set_subject_name(cer, req->req_info->subject);
 343                                         X509_gmtime_adj(X509_get_notBefore(cer),0);
 344                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 345                                         req_pkey = X509_REQ_get_pubkey(req);
 346                                         X509_set_pubkey(cer, req_pkey);
 347                                         EVP_PKEY_free(req_pkey);
 348
 349                                         /* Sign the cert */
 350                                         if (!X509_sign(cer, pk, EVP_md5())) {
 351                                                 lprintf(CTDL_CRIT, "X509_sign(): error\n");
 352                                         }
 353                                         else {
 354                                                 /* Write it to disk. */
 355                                                 fp = fopen(CTDL_CER_PATH, "w");
 356                                                 if (fp != NULL) {
 357                                                         chmod(CTDL_CER_PATH, 0600);
 358                                                         PEM_write_X509(fp, cer);
 359                                                         fclose(fp);
 360                                                 }
 361                                         }
 362                                         X509_free(cer);
 363                                 }
 364                         }
 365
 366                         RSA_free(rsa);
 367                 }
 368         }
 369
 370
 371         /*
 372          * Now try to bind to the key and certificate.
 373          */
 374         if (ctdl_install_certificate(ssl_ctx,
 375                         CTDL_CER_PATH,
 376                         CTDL_KEY_PATH) != 1)
 377         {
 378                 lprintf(CTDL_CRIT, "Cannot install certificate: %s\n",
 379                                 ERR_reason_error_string(ERR_get_error()));
 380         }
 381
 382         /* Finally let the server know we're here */
 383         CtdlRegisterProtoHook(cmd_stls, "STLS", "Start SSL/TLS session");
 384         CtdlRegisterProtoHook(cmd_gtls, "GTLS",
 385                               "Get SSL/TLS session status");
 386         CtdlRegisterSessionHook(endtls, EVT_STOP);
 387 }
 388
 389
 390 /*
 391  * client_write_ssl() Send binary data to the client encrypted.
 392  */
 393 void client_write_ssl(char *buf, int nbytes)
 394 {
 395         int retval;
 396         int nremain;
 397         char junk[1];
 398
 399         nremain = nbytes;
 400
 401         while (nremain > 0) {
 402                 if (SSL_want_write(CC->ssl)) {
 403                         if ((SSL_read(CC->ssl, junk, 0)) < 1) {
 404                                 lprintf(CTDL_DEBUG, "SSL_read in client_write: %s\n", ERR_reason_error_string(ERR_get_error()));
 405                         }
 406                 }
 407                 retval =
 408                     SSL_write(CC->ssl, &buf[nbytes - nremain], nremain);
 409                 if (retval < 1) {
 410                         long errval;
 411
 412                         errval = SSL_get_error(CC->ssl, retval);
 413                         if (errval == SSL_ERROR_WANT_READ ||
 414                             errval == SSL_ERROR_WANT_WRITE) {
 415                                 sleep(1);
 416                                 continue;
 417                         }
 418                         lprintf(CTDL_DEBUG, "SSL_write got error %ld, ret %d\n", errval, retval);
 419                         if (retval == -1)
 420                                 lprintf(CTDL_DEBUG, "errno is %d\n", errno);
 421                         endtls();
 422                         client_write(&buf[nbytes - nremain], nremain);
 423                         return;
 424                 }
 425                 nremain -= retval;
 426         }
 427 }
 428
 429
 430 /*
 431  * client_read_ssl() - read data from the encrypted layer.
 432  */
 433 int client_read_ssl(char *buf, int bytes, int timeout)
 434 {
 435 #if 0
 436         fd_set rfds;
 437         struct timeval tv;
 438         int retval;
 439         int s;
 440 #endif
 441         int len, rlen;
 442         char junk[1];
 443
 444         len = 0;
 445         while (len < bytes) {
 446 #if 0
 447                 /*
 448                  * This code is disabled because we don't need it when
 449                  * using blocking reads (which we are). -IO
 450                  */
 451                 FD_ZERO(&rfds);
 452                 s = BIO_get_fd(CC->ssl->rbio, NULL);
 453                 FD_SET(s, &rfds);
 454                 tv.tv_sec = timeout;
 455                 tv.tv_usec = 0;
 456
 457                 retval = select(s + 1, &rfds, NULL, NULL, &tv);
 458
 459                 if (FD_ISSET(s, &rfds) == 0) {
 460                         return (0);
 461                 }
 462
 463 #endif
 464                 if (SSL_want_read(CC->ssl)) {
 465                         if ((SSL_write(CC->ssl, junk, 0)) < 1) {
 466                                 lprintf(CTDL_DEBUG, "SSL_write in client_read: %s\n", ERR_reason_error_string(ERR_get_error()));
 467                         }
 468                 }
 469                 rlen = SSL_read(CC->ssl, &buf[len], bytes - len);
 470                 if (rlen < 1) {
 471                         long errval;
 472
 473                         errval = SSL_get_error(CC->ssl, rlen);
 474                         if (errval == SSL_ERROR_WANT_READ ||
 475                             errval == SSL_ERROR_WANT_WRITE) {
 476                                 sleep(1);
 477                                 continue;
 478                         }
 479                         lprintf(CTDL_DEBUG, "SSL_read got error %ld\n", errval);
 480                         endtls();
 481                         return (client_read_to
 482                                 (&buf[len], bytes - len, timeout));
 483                 }
 484                 len += rlen;
 485         }
 486         return (1);
 487 }
 488
 489
 490 /*
 491  * CtdlStartTLS() starts SSL/TLS encryption for the current session.  It
 492  * must be supplied with pre-generated strings for responses of "ok," "no
 493  * support for TLS," and "error" so that we can use this in any protocol.
 494  */
 495 void CtdlStartTLS(char *ok_response, char *nosup_response,
 496                         char *error_response) {
 497
 498         int retval, bits, alg_bits;
 499
 500         if (!ssl_ctx) {
 501                 cprintf("%s", nosup_response);
 502                 return;
 503         }
 504         if (!(CC->ssl = SSL_new(ssl_ctx))) {
 505                 lprintf(CTDL_CRIT, "SSL_new failed: %s\n",
 506                                 ERR_reason_error_string(ERR_get_error()));
 507                 cprintf("%s", error_response);
 508                 return;
 509         }
 510         if (!(SSL_set_fd(CC->ssl, CC->client_socket))) {
 511                 lprintf(CTDL_CRIT, "SSL_set_fd failed: %s\n",
 512                         ERR_reason_error_string(ERR_get_error()));
 513                 SSL_free(CC->ssl);
 514                 CC->ssl = NULL;
 515                 cprintf("%s", error_response);
 516                 return;
 517         }
 518         cprintf("%s", ok_response);
 519         retval = SSL_accept(CC->ssl);
 520         if (retval < 1) {
 521                 /*
 522                  * Can't notify the client of an error here; they will
 523                  * discover the problem at the SSL layer and should
 524                  * revert to unencrypted communications.
 525                  */
 526                 long errval;
 527
 528                 errval = SSL_get_error(CC->ssl, retval);
 529                 lprintf(CTDL_CRIT, "SSL_accept failed: %s\n",
 530                         ERR_reason_error_string(ERR_get_error()));
 531                 SSL_free(CC->ssl);
 532                 CC->ssl = NULL;
 533                 return;
 534         }
 535         BIO_set_close(CC->ssl->rbio, BIO_NOCLOSE);
 536         bits =
 537             SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl),
 538                                 &alg_bits);
 539         lprintf(CTDL_INFO, "SSL/TLS using %s on %s (%d of %d bits)\n",
 540                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 541                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 542                 bits, alg_bits);
 543         CC->redirect_ssl = 1;
 544 }
 545
 546
 547 /*
 548  * cmd_stls() starts SSL/TLS encryption for the current session
 549  */
 550 void cmd_stls(char *params)
 551 {
 552         char ok_response[SIZ];
 553         char nosup_response[SIZ];
 554         char error_response[SIZ];
 555
 556         sprintf(ok_response,
 557                 "%d Begin TLS negotiation now\n",
 558                 CIT_OK);
 559         sprintf(nosup_response,
 560                 "%d TLS not supported here\n",
 561                 ERROR + CMD_NOT_SUPPORTED);
 562         sprintf(error_response,
 563                 "%d TLS negotiation error\n",
 564                 ERROR + INTERNAL_ERROR);
 565
 566         CtdlStartTLS(ok_response, nosup_response, error_response);
 567 }
 568
 569
 570 /*
 571  * cmd_gtls() returns status info about the TLS connection
 572  */
 573 void cmd_gtls(char *params)
 574 {
 575         int bits, alg_bits;
 576
 577         if (!CC->ssl || !CC->redirect_ssl) {
 578                 cprintf("%d Session is not encrypted.\n", ERROR);
 579                 return;
 580         }
 581         bits =
 582             SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl),
 583                                 &alg_bits);
 584         cprintf("%d %s|%s|%d|%d\n", CIT_OK,
 585                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 586                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 587                 alg_bits, bits);
 588 }
 589
 590
 591 /*
 592  * endtls() shuts down the TLS connection
 593  *
 594  * WARNING:  This may make your session vulnerable to a known plaintext
 595  * attack in the current implmentation.
 596  */
 597 void endtls(void)
 598 {
 599         lprintf(CTDL_INFO, "Ending SSL/TLS\n");
 600
 601         if (!CC->ssl) {
 602                 CC->redirect_ssl = 0;
 603                 return;
 604         }
 605
 606         SSL_shutdown(CC->ssl);
 607         SSL_free(CC->ssl);
 608         CC->ssl = NULL;
 609         CC->redirect_ssl = 0;
 610 }
 611
 612
 613 /*
 614  * ssl_lock() callback for OpenSSL mutex locks
 615  */
 616 void ssl_lock(int mode, int n, const char *file, int line)
 617 {
 618         if (mode & CRYPTO_LOCK)
 619                 pthread_mutex_lock(SSLCritters[n]);
 620         else
 621                 pthread_mutex_unlock(SSLCritters[n]);
 622 }
 623 #endif                          /* HAVE_OPENSSL */