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 void destruct_ssl(void)
  53 {
  54         int a;
  55         CtdlUnregisterProtoHook(cmd_stls, "STLS");
  56         CtdlUnregisterProtoHook(cmd_gtls, "GTLS");
  57         for (a = 0; a < CRYPTO_num_locks(); a++)
  58                 free(SSLCritters[a]);
  59         free (SSLCritters);
  60 }
  61
  62 void init_ssl(void)
  63 {
  64         SSL_METHOD *ssl_method;
  65         DH *dh;
  66         RSA *rsa=NULL;
  67         X509_REQ *req = NULL;
  68         X509 *cer = NULL;
  69         EVP_PKEY *pk = NULL;
  70         EVP_PKEY *req_pkey = NULL;
  71         X509_NAME *name = NULL;
  72         FILE *fp;
  73
  74         if (!access(EGD_POOL, F_OK))
  75                 RAND_egd(EGD_POOL);
  76
  77         if (!RAND_status()) {
  78                 lprintf(CTDL_CRIT,
  79                         "PRNG not adequately seeded, won't do SSL/TLS\n");
  80                 return;
  81         }
  82         SSLCritters =
  83             malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
  84         if (!SSLCritters) {
  85                 lprintf(CTDL_EMERG, "citserver: can't allocate memory!!\n");
  86                 /* Nothing's been initialized, just die */
  87                 exit(1);
  88         } else {
  89                 int a;
  90
  91                 for (a = 0; a < CRYPTO_num_locks(); a++) {
  92                         SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
  93                         if (!SSLCritters[a]) {
  94                                 lprintf(CTDL_EMERG,
  95                                         "citserver: can't allocate memory!!\n");
  96                                 /* Nothing's been initialized, just die */
  97                                 exit(1);
  98                         }
  99                         pthread_mutex_init(SSLCritters[a], NULL);
 100                 }
 101         }
 102
 103         /*
 104          * Initialize SSL transport layer
 105          */
 106         SSL_library_init();
 107         SSL_load_error_strings();
 108         ssl_method = SSLv23_server_method();
 109         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
 110                 lprintf(CTDL_CRIT, "SSL_CTX_new failed: %s\n",
 111                         ERR_reason_error_string(ERR_get_error()));
 112                 return;
 113         }
 114         if (!(SSL_CTX_set_cipher_list(ssl_ctx, CIT_CIPHERS))) {
 115                 lprintf(CTDL_CRIT, "SSL: No ciphers available\n");
 116                 SSL_CTX_free(ssl_ctx);
 117                 ssl_ctx = NULL;
 118                 return;
 119         }
 120 #if 0
 121 #if SSLEAY_VERSION_NUMBER >= 0x00906000L
 122         SSL_CTX_set_mode(ssl_ctx, SSL_CTX_get_mode(ssl_ctx) |
 123                          SSL_MODE_AUTO_RETRY);
 124 #endif
 125 #endif
 126
 127         CRYPTO_set_locking_callback(ssl_lock);
 128         CRYPTO_set_id_callback(id_callback);
 129
 130         /* Load DH parameters into the context */
 131         dh = DH_new();
 132         if (!dh) {
 133                 lprintf(CTDL_CRIT, "init_ssl() can't allocate a DH object: %s\n",
 134                         ERR_reason_error_string(ERR_get_error()));
 135                 SSL_CTX_free(ssl_ctx);
 136                 ssl_ctx = NULL;
 137                 return;
 138         }
 139         if (!(BN_hex2bn(&(dh->p), DH_P))) {
 140                 lprintf(CTDL_CRIT, "init_ssl() can't assign DH_P: %s\n",
 141                         ERR_reason_error_string(ERR_get_error()));
 142                 SSL_CTX_free(ssl_ctx);
 143                 ssl_ctx = NULL;
 144                 return;
 145         }
 146         if (!(BN_hex2bn(&(dh->g), DH_G))) {
 147                 lprintf(CTDL_CRIT, "init_ssl() can't assign DH_G: %s\n",
 148                         ERR_reason_error_string(ERR_get_error()));
 149                 SSL_CTX_free(ssl_ctx);
 150                 ssl_ctx = NULL;
 151                 return;
 152         }
 153         dh->length = DH_L;
 154         SSL_CTX_set_tmp_dh(ssl_ctx, dh);
 155         DH_free(dh);
 156
 157         /* Get our certificates in order.
 158          * First, create the key/cert directory if it's not there already...
 159          */
 160         mkdir(ctdl_key_dir, 0700);
 161
 162         /*
 163          * Generate a key pair if we don't have one.
 164          */
 165         if (access(file_crpt_file_key, R_OK) != 0) {
 166                 lprintf(CTDL_INFO, "Generating RSA key pair.\n");
 167                 rsa = RSA_generate_key(1024,    /* modulus size */
 168                                         65537,  /* exponent */
 169                                         NULL,   /* no callback */
 170                                         NULL);  /* no callback */
 171                 if (rsa == NULL) {
 172                         lprintf(CTDL_CRIT, "Key generation failed: %s\n",
 173                                 ERR_reason_error_string(ERR_get_error()));
 174                 }
 175                 if (rsa != NULL) {
 176                         fp = fopen(file_crpt_file_key, "w");
 177                         if (fp != NULL) {
 178                                 chmod(file_crpt_file_key, 0600);
 179                                 if (PEM_write_RSAPrivateKey(fp, /* the file */
 180                                                         rsa,    /* the key */
 181                                                         NULL,   /* no enc */
 182                                                         NULL,   /* no passphr */
 183                                                         0,      /* no passphr */
 184                                                         NULL,   /* no callbk */
 185                                                         NULL    /* no callbk */
 186                                 ) != 1) {
 187                                         lprintf(CTDL_CRIT, "Cannot write key: %s\n",
 188                                                 ERR_reason_error_string(ERR_get_error()));
 189                                         unlink(file_crpt_file_key);
 190                                 }
 191                                 fclose(fp);
 192                         }
 193                         RSA_free(rsa);
 194                 }
 195         }
 196
 197         /*
 198          * Generate a CSR if we don't have one.
 199          */
 200         if (access(file_crpt_file_csr, R_OK) != 0) {
 201                 lprintf(CTDL_INFO, "Generating a certificate signing request.\n");
 202
 203                 /*
 204                  * Read our key from the file.  No, we don't just keep this
 205                  * in memory from the above key-generation function, because
 206                  * there is the possibility that the key was already on disk
 207                  * and we didn't just generate it now.
 208                  */
 209                 fp = fopen(file_crpt_file_key, "r");
 210                 if (fp) {
 211                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 212                         fclose(fp);
 213                 }
 214
 215                 if (rsa) {
 216
 217                         /* Create a public key from the private key */
 218                         if (pk=EVP_PKEY_new(), pk != NULL) {
 219                                 EVP_PKEY_assign_RSA(pk, rsa);
 220                                 if (req = X509_REQ_new(), req != NULL) {
 221
 222                                         /* Set the public key */
 223                                         X509_REQ_set_pubkey(req, pk);
 224                                         X509_REQ_set_version(req, 0L);
 225
 226                                         name = X509_REQ_get_subject_name(req);
 227
 228                                         /* Tell it who we are */
 229
 230                                         /*
 231                                         X509_NAME_add_entry_by_txt(name, "C",
 232                                                 MBSTRING_ASC, "US", -1, -1, 0);
 233
 234                                         X509_NAME_add_entry_by_txt(name, "ST",
 235                                                 MBSTRING_ASC, "New York", -1, -1, 0);
 236
 237                                         X509_NAME_add_entry_by_txt(name, "L",
 238                                                 MBSTRING_ASC, "Mount Kisco", -1, -1, 0);
 239                                         */
 240
 241                                         X509_NAME_add_entry_by_txt(name, "O",
 242                                                 MBSTRING_ASC, config.c_humannode, -1, -1, 0);
 243
 244                                         X509_NAME_add_entry_by_txt(name, "OU",
 245                                                 MBSTRING_ASC, "Citadel server", -1, -1, 0);
 246
 247                                         /* X509_NAME_add_entry_by_txt(name, "CN",
 248                                                 MBSTRING_ASC, config.c_fqdn, -1, -1, 0);
 249                                         */
 250
 251                                         X509_NAME_add_entry_by_txt(name, "CN",
 252                                                 MBSTRING_ASC, "*", -1, -1, 0);
 253
 254                                         X509_REQ_set_subject_name(req, name);
 255
 256                                         /* Sign the CSR */
 257                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 258                                                 lprintf(CTDL_CRIT, "X509_REQ_sign(): error\n");
 259                                         }
 260                                         else {
 261                                                 /* Write it to disk. */
 262                                                 fp = fopen(file_crpt_file_csr, "w");
 263                                                 if (fp != NULL) {
 264                                                         chmod(file_crpt_file_csr, 0600);
 265                                                         PEM_write_X509_REQ(fp, req);
 266                                                         fclose(fp);
 267                                                 }
 268                                         }
 269
 270                                         X509_REQ_free(req);
 271                                 }
 272                         }
 273
 274                         RSA_free(rsa);
 275                 }
 276
 277                 else {
 278                         lprintf(CTDL_CRIT, "Unable to read private key.\n");
 279                 }
 280         }
 281
 282
 283
 284         /*
 285          * Generate a self-signed certificate if we don't have one.
 286          */
 287         if (access(file_crpt_file_cer, R_OK) != 0) {
 288                 lprintf(CTDL_INFO, "Generating a self-signed certificate.\n");
 289
 290                 /* Same deal as before: always read the key from disk because
 291                  * it may or may not have just been generated.
 292                  */
 293                 fp = fopen(file_crpt_file_key, "r");
 294                 if (fp) {
 295                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 296                         fclose(fp);
 297                 }
 298
 299                 /* This also holds true for the CSR. */
 300                 req = NULL;
 301                 cer = NULL;
 302                 pk = NULL;
 303                 if (rsa) {
 304                         if (pk=EVP_PKEY_new(), pk != NULL) {
 305                                 EVP_PKEY_assign_RSA(pk, rsa);
 306                         }
 307
 308                         fp = fopen(file_crpt_file_csr, "r");
 309                         if (fp) {
 310                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 311                                 fclose(fp);
 312                         }
 313
 314                         if (req) {
 315                                 if (cer = X509_new(), cer != NULL) {
 316
 317                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 318                                         X509_set_issuer_name(cer, req->req_info->subject);
 319                                         X509_set_subject_name(cer, req->req_info->subject);
 320                                         X509_gmtime_adj(X509_get_notBefore(cer),0);
 321                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 322                                         req_pkey = X509_REQ_get_pubkey(req);
 323                                         X509_set_pubkey(cer, req_pkey);
 324                                         EVP_PKEY_free(req_pkey);
 325
 326                                         /* Sign the cert */
 327                                         if (!X509_sign(cer, pk, EVP_md5())) {
 328                                                 lprintf(CTDL_CRIT, "X509_sign(): error\n");
 329                                         }
 330                                         else {
 331                                                 /* Write it to disk. */
 332                                                 fp = fopen(file_crpt_file_cer, "w");
 333                                                 if (fp != NULL) {
 334                                                         chmod(file_crpt_file_cer, 0600);
 335                                                         PEM_write_X509(fp, cer);
 336                                                         fclose(fp);
 337                                                 }
 338                                         }
 339                                         X509_free(cer);
 340                                 }
 341                         }
 342
 343                         RSA_free(rsa);
 344                 }
 345         }
 346
 347
 348         /*
 349          * Now try to bind to the key and certificate.
 350          */
 351         SSL_CTX_use_certificate_chain_file(ssl_ctx, file_crpt_file_cer);
 352         SSL_CTX_use_PrivateKey_file(ssl_ctx, file_crpt_file_key, SSL_FILETYPE_PEM);
 353         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 354                 lprintf(CTDL_CRIT, "Cannot install certificate: %s\n",
 355                                 ERR_reason_error_string(ERR_get_error()));
 356         }
 357
 358         /* Finally let the server know we're here */
 359         CtdlRegisterProtoHook(cmd_stls, "STLS", "Start SSL/TLS session");
 360         CtdlRegisterProtoHook(cmd_gtls, "GTLS",
 361                               "Get SSL/TLS session status");
 362         CtdlRegisterSessionHook(endtls, EVT_STOP);
 363 }
 364
 365
 366 /*
 367  * client_write_ssl() Send binary data to the client encrypted.
 368  */
 369 void client_write_ssl(char *buf, int nbytes)
 370 {
 371         int retval;
 372         int nremain;
 373         char junk[1];
 374
 375         nremain = nbytes;
 376
 377         while (nremain > 0) {
 378                 if (SSL_want_write(CC->ssl)) {
 379                         if ((SSL_read(CC->ssl, junk, 0)) < 1) {
 380                                 lprintf(CTDL_DEBUG, "SSL_read in client_write: %s\n", ERR_reason_error_string(ERR_get_error()));
 381                         }
 382                 }
 383                 retval =
 384                     SSL_write(CC->ssl, &buf[nbytes - nremain], nremain);
 385                 if (retval < 1) {
 386                         long errval;
 387
 388                         errval = SSL_get_error(CC->ssl, retval);
 389                         if (errval == SSL_ERROR_WANT_READ ||
 390                             errval == SSL_ERROR_WANT_WRITE) {
 391                                 sleep(1);
 392                                 continue;
 393                         }
 394                         lprintf(CTDL_DEBUG, "SSL_write got error %ld, ret %d\n", errval, retval);
 395                         if (retval == -1)
 396                                 lprintf(CTDL_DEBUG, "errno is %d\n", errno);
 397                         endtls();
 398                         client_write(&buf[nbytes - nremain], nremain);
 399                         return;
 400                 }
 401                 nremain -= retval;
 402         }
 403 }
 404
 405
 406 /*
 407  * client_read_ssl() - read data from the encrypted layer.
 408  */
 409 int client_read_ssl(char *buf, int bytes, int timeout)
 410 {
 411 #if 0
 412         fd_set rfds;
 413         struct timeval tv;
 414         int retval;
 415         int s;
 416 #endif
 417         int len, rlen;
 418         char junk[1];
 419
 420         len = 0;
 421         while (len < bytes) {
 422 #if 0
 423                 /*
 424                  * This code is disabled because we don't need it when
 425                  * using blocking reads (which we are). -IO
 426                  */
 427                 FD_ZERO(&rfds);
 428                 s = BIO_get_fd(CC->ssl->rbio, NULL);
 429                 FD_SET(s, &rfds);
 430                 tv.tv_sec = timeout;
 431                 tv.tv_usec = 0;
 432
 433                 retval = select(s + 1, &rfds, NULL, NULL, &tv);
 434
 435                 if (FD_ISSET(s, &rfds) == 0) {
 436                         return (0);
 437                 }
 438
 439 #endif
 440                 if (SSL_want_read(CC->ssl)) {
 441                         if ((SSL_write(CC->ssl, junk, 0)) < 1) {
 442                                 lprintf(CTDL_DEBUG, "SSL_write in client_read: %s\n", ERR_reason_error_string(ERR_get_error()));
 443                         }
 444                 }
 445                 rlen = SSL_read(CC->ssl, &buf[len], bytes - len);
 446                 if (rlen < 1) {
 447                         long errval;
 448
 449                         errval = SSL_get_error(CC->ssl, rlen);
 450                         if (errval == SSL_ERROR_WANT_READ ||
 451                             errval == SSL_ERROR_WANT_WRITE) {
 452                                 sleep(1);
 453                                 continue;
 454                         }
 455                         lprintf(CTDL_DEBUG, "SSL_read got error %ld\n", errval);
 456                         endtls();
 457                         return (client_read_to
 458                                 (&buf[len], bytes - len, timeout));
 459                 }
 460                 len += rlen;
 461         }
 462         return (1);
 463 }
 464
 465
 466 /*
 467  * CtdlStartTLS() starts SSL/TLS encryption for the current session.  It
 468  * must be supplied with pre-generated strings for responses of "ok," "no
 469  * support for TLS," and "error" so that we can use this in any protocol.
 470  */
 471 void CtdlStartTLS(char *ok_response, char *nosup_response,
 472                         char *error_response) {
 473
 474         int retval, bits, alg_bits;
 475
 476         if (!ssl_ctx) {
 477                 lprintf(CTDL_CRIT, "SSL failed: no ssl_ctx exists?\n");
 478                 if (nosup_response != NULL) cprintf("%s", nosup_response);
 479                 return;
 480         }
 481         if (!(CC->ssl = SSL_new(ssl_ctx))) {
 482                 lprintf(CTDL_CRIT, "SSL_new failed: %s\n",
 483                                 ERR_reason_error_string(ERR_get_error()));
 484                 if (error_response != NULL) cprintf("%s", error_response);
 485                 return;
 486         }
 487         if (!(SSL_set_fd(CC->ssl, CC->client_socket))) {
 488                 lprintf(CTDL_CRIT, "SSL_set_fd failed: %s\n",
 489                         ERR_reason_error_string(ERR_get_error()));
 490                 SSL_free(CC->ssl);
 491                 CC->ssl = NULL;
 492                 if (error_response != NULL) cprintf("%s", error_response);
 493                 return;
 494         }
 495         if (ok_response != NULL) cprintf("%s", ok_response);
 496         retval = SSL_accept(CC->ssl);
 497         if (retval < 1) {
 498                 /*
 499                  * Can't notify the client of an error here; they will
 500                  * discover the problem at the SSL layer and should
 501                  * revert to unencrypted communications.
 502                  */
 503                 long errval;
 504                 char error_string[128];
 505
 506                 errval = SSL_get_error(CC->ssl, retval);
 507                 lprintf(CTDL_CRIT, "SSL_accept failed: retval=%d, errval=%ld, err=%s\n",
 508                         retval,
 509                         errval,
 510                         ERR_error_string(errval, error_string)
 511                 );
 512                 SSL_free(CC->ssl);
 513                 CC->ssl = NULL;
 514                 return;
 515         }
 516         BIO_set_close(CC->ssl->rbio, BIO_NOCLOSE);
 517         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl), &alg_bits);
 518         lprintf(CTDL_INFO, "SSL/TLS using %s on %s (%d of %d bits)\n",
 519                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 520                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 521                 bits, alg_bits);
 522         CC->redirect_ssl = 1;
 523 }
 524
 525
 526 /*
 527  * cmd_stls() starts SSL/TLS encryption for the current session
 528  */
 529 void cmd_stls(char *params)
 530 {
 531         char ok_response[SIZ];
 532         char nosup_response[SIZ];
 533         char error_response[SIZ];
 534
 535         unbuffer_output();
 536
 537         sprintf(ok_response,
 538                 "%d Begin TLS negotiation now\n",
 539                 CIT_OK);
 540         sprintf(nosup_response,
 541                 "%d TLS not supported here\n",
 542                 ERROR + CMD_NOT_SUPPORTED);
 543         sprintf(error_response,
 544                 "%d TLS negotiation error\n",
 545                 ERROR + INTERNAL_ERROR);
 546
 547         CtdlStartTLS(ok_response, nosup_response, error_response);
 548 }
 549
 550
 551 /*
 552  * cmd_gtls() returns status info about the TLS connection
 553  */
 554 void cmd_gtls(char *params)
 555 {
 556         int bits, alg_bits;
 557
 558         if (!CC->ssl || !CC->redirect_ssl) {
 559                 cprintf("%d Session is not encrypted.\n", ERROR);
 560                 return;
 561         }
 562         bits =
 563             SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl),
 564                                 &alg_bits);
 565         cprintf("%d %s|%s|%d|%d\n", CIT_OK,
 566                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 567                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 568                 alg_bits, bits);
 569 }
 570
 571
 572 /*
 573  * endtls() shuts down the TLS connection
 574  *
 575  * WARNING:  This may make your session vulnerable to a known plaintext
 576  * attack in the current implmentation.
 577  */
 578 void endtls(void)
 579 {
 580         if (!CC->ssl) {
 581                 CC->redirect_ssl = 0;
 582                 return;
 583         }
 584
 585         lprintf(CTDL_INFO, "Ending SSL/TLS\n");
 586         SSL_shutdown(CC->ssl);
 587         SSL_free(CC->ssl);
 588         CC->ssl = NULL;
 589         CC->redirect_ssl = 0;
 590 }
 591
 592
 593 /*
 594  * ssl_lock() callback for OpenSSL mutex locks
 595  */
 596 void ssl_lock(int mode, int n, const char *file, int line)
 597 {
 598         if (mode & CRYPTO_LOCK)
 599                 pthread_mutex_lock(SSLCritters[n]);
 600         else
 601                 pthread_mutex_unlock(SSLCritters[n]);
 602 }
 603 #endif                          /* HAVE_OPENSSL */