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 "citadel.h"
  39 #include "config.h"
  40
  41
  42 #include "ctdl_module.h"
  43 /* TODO: should we use the standard module init stuff to start this? */
  44 /* TODO: should we register an event handler to call destruct_ssl? */
  45
  46 #ifdef HAVE_OPENSSL
  47 SSL_CTX *ssl_ctx;               /* SSL context */
  48 pthread_mutex_t **SSLCritters;  /* Things needing locking */
  49
  50 static unsigned long id_callback(void)
  51 {
  52         return (unsigned long) pthread_self();
  53 }
  54
  55 void destruct_ssl(void)
  56 {
  57         int a;
  58         CtdlUnregisterProtoHook(cmd_stls, "STLS");
  59         CtdlUnregisterProtoHook(cmd_gtls, "GTLS");
  60         for (a = 0; a < CRYPTO_num_locks(); a++)
  61                 free(SSLCritters[a]);
  62         free (SSLCritters);
  63 }
  64
  65 void init_ssl(void)
  66 {
  67         SSL_METHOD *ssl_method;
  68         DH *dh;
  69         RSA *rsa=NULL;
  70         X509_REQ *req = NULL;
  71         X509 *cer = NULL;
  72         EVP_PKEY *pk = NULL;
  73         EVP_PKEY *req_pkey = NULL;
  74         X509_NAME *name = NULL;
  75         FILE *fp;
  76
  77         if (!access(EGD_POOL, F_OK))
  78                 RAND_egd(EGD_POOL);
  79
  80         if (!RAND_status()) {
  81                 lprintf(CTDL_CRIT,
  82                         "PRNG not adequately seeded, won't do SSL/TLS\n");
  83                 return;
  84         }
  85         SSLCritters =
  86             malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
  87         if (!SSLCritters) {
  88                 lprintf(CTDL_EMERG, "citserver: can't allocate memory!!\n");
  89                 /* Nothing's been initialized, just die */
  90                 exit(1);
  91         } else {
  92                 int a;
  93
  94                 for (a = 0; a < CRYPTO_num_locks(); a++) {
  95                         SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
  96                         if (!SSLCritters[a]) {
  97                                 lprintf(CTDL_EMERG,
  98                                         "citserver: can't allocate memory!!\n");
  99                                 /* Nothing's been initialized, just die */
 100                                 exit(1);
 101                         }
 102                         pthread_mutex_init(SSLCritters[a], NULL);
 103                 }
 104         }
 105
 106         /*
 107          * Initialize SSL transport layer
 108          */
 109         SSL_library_init();
 110         SSL_load_error_strings();
 111         ssl_method = SSLv23_server_method();
 112         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
 113                 lprintf(CTDL_CRIT, "SSL_CTX_new failed: %s\n",
 114                         ERR_reason_error_string(ERR_get_error()));
 115                 return;
 116         }
 117         if (!(SSL_CTX_set_cipher_list(ssl_ctx, CIT_CIPHERS))) {
 118                 lprintf(CTDL_CRIT, "SSL: No ciphers available\n");
 119                 SSL_CTX_free(ssl_ctx);
 120                 ssl_ctx = NULL;
 121                 return;
 122         }
 123 #if 0
 124 #if SSLEAY_VERSION_NUMBER >= 0x00906000L
 125         SSL_CTX_set_mode(ssl_ctx, SSL_CTX_get_mode(ssl_ctx) |
 126                          SSL_MODE_AUTO_RETRY);
 127 #endif
 128 #endif
 129
 130         CRYPTO_set_locking_callback(ssl_lock);
 131         CRYPTO_set_id_callback(id_callback);
 132
 133         /* Load DH parameters into the context */
 134         dh = DH_new();
 135         if (!dh) {
 136                 lprintf(CTDL_CRIT, "init_ssl() can't allocate a DH object: %s\n",
 137                         ERR_reason_error_string(ERR_get_error()));
 138                 SSL_CTX_free(ssl_ctx);
 139                 ssl_ctx = NULL;
 140                 return;
 141         }
 142         if (!(BN_hex2bn(&(dh->p), DH_P))) {
 143                 lprintf(CTDL_CRIT, "init_ssl() can't assign DH_P: %s\n",
 144                         ERR_reason_error_string(ERR_get_error()));
 145                 SSL_CTX_free(ssl_ctx);
 146                 ssl_ctx = NULL;
 147                 return;
 148         }
 149         if (!(BN_hex2bn(&(dh->g), DH_G))) {
 150                 lprintf(CTDL_CRIT, "init_ssl() can't assign DH_G: %s\n",
 151                         ERR_reason_error_string(ERR_get_error()));
 152                 SSL_CTX_free(ssl_ctx);
 153                 ssl_ctx = NULL;
 154                 return;
 155         }
 156         dh->length = DH_L;
 157         SSL_CTX_set_tmp_dh(ssl_ctx, dh);
 158         DH_free(dh);
 159
 160         /* Get our certificates in order.
 161          * First, create the key/cert directory if it's not there already...
 162          */
 163         mkdir(ctdl_key_dir, 0700);
 164
 165         /*
 166          * Generate a key pair if we don't have one.
 167          */
 168         if (access(file_crpt_file_key, R_OK) != 0) {
 169                 lprintf(CTDL_INFO, "Generating RSA key pair.\n");
 170                 rsa = RSA_generate_key(1024,    /* modulus size */
 171                                         65537,  /* exponent */
 172                                         NULL,   /* no callback */
 173                                         NULL);  /* no callback */
 174                 if (rsa == NULL) {
 175                         lprintf(CTDL_CRIT, "Key generation failed: %s\n",
 176                                 ERR_reason_error_string(ERR_get_error()));
 177                 }
 178                 if (rsa != NULL) {
 179                         fp = fopen(file_crpt_file_key, "w");
 180                         if (fp != NULL) {
 181                                 chmod(file_crpt_file_key, 0600);
 182                                 if (PEM_write_RSAPrivateKey(fp, /* the file */
 183                                                         rsa,    /* the key */
 184                                                         NULL,   /* no enc */
 185                                                         NULL,   /* no passphr */
 186                                                         0,      /* no passphr */
 187                                                         NULL,   /* no callbk */
 188                                                         NULL    /* no callbk */
 189                                 ) != 1) {
 190                                         lprintf(CTDL_CRIT, "Cannot write key: %s\n",
 191                                                 ERR_reason_error_string(ERR_get_error()));
 192                                         unlink(file_crpt_file_key);
 193                                 }
 194                                 fclose(fp);
 195                         }
 196                         RSA_free(rsa);
 197                 }
 198         }
 199
 200         /*
 201          * Generate a CSR if we don't have one.
 202          */
 203         if (access(file_crpt_file_csr, R_OK) != 0) {
 204                 lprintf(CTDL_INFO, "Generating a certificate signing request.\n");
 205
 206                 /*
 207                  * Read our key from the file.  No, we don't just keep this
 208                  * in memory from the above key-generation function, because
 209                  * there is the possibility that the key was already on disk
 210                  * and we didn't just generate it now.
 211                  */
 212                 fp = fopen(file_crpt_file_key, "r");
 213                 if (fp) {
 214                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 215                         fclose(fp);
 216                 }
 217
 218                 if (rsa) {
 219
 220                         /* Create a public key from the private key */
 221                         if (pk=EVP_PKEY_new(), pk != NULL) {
 222                                 EVP_PKEY_assign_RSA(pk, rsa);
 223                                 if (req = X509_REQ_new(), req != NULL) {
 224
 225                                         /* Set the public key */
 226                                         X509_REQ_set_pubkey(req, pk);
 227                                         X509_REQ_set_version(req, 0L);
 228
 229                                         name = X509_REQ_get_subject_name(req);
 230
 231                                         /* Tell it who we are */
 232
 233                                         /*
 234                                         X509_NAME_add_entry_by_txt(name, "C",
 235                                                 MBSTRING_ASC, "US", -1, -1, 0);
 236
 237                                         X509_NAME_add_entry_by_txt(name, "ST",
 238                                                 MBSTRING_ASC, "New York", -1, -1, 0);
 239
 240                                         X509_NAME_add_entry_by_txt(name, "L",
 241                                                 MBSTRING_ASC, "Mount Kisco", -1, -1, 0);
 242                                         */
 243
 244                                         X509_NAME_add_entry_by_txt(name, "O",
 245                                                 MBSTRING_ASC, config.c_humannode, -1, -1, 0);
 246
 247                                         X509_NAME_add_entry_by_txt(name, "OU",
 248                                                 MBSTRING_ASC, "Citadel server", -1, -1, 0);
 249
 250                                         /* X509_NAME_add_entry_by_txt(name, "CN",
 251                                                 MBSTRING_ASC, config.c_fqdn, -1, -1, 0);
 252                                         */
 253
 254                                         X509_NAME_add_entry_by_txt(name, "CN",
 255                                                 MBSTRING_ASC, "*", -1, -1, 0);
 256
 257                                         X509_REQ_set_subject_name(req, name);
 258
 259                                         /* Sign the CSR */
 260                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 261                                                 lprintf(CTDL_CRIT, "X509_REQ_sign(): error\n");
 262                                         }
 263                                         else {
 264                                                 /* Write it to disk. */
 265                                                 fp = fopen(file_crpt_file_csr, "w");
 266                                                 if (fp != NULL) {
 267                                                         chmod(file_crpt_file_csr, 0600);
 268                                                         PEM_write_X509_REQ(fp, req);
 269                                                         fclose(fp);
 270                                                 }
 271                                         }
 272
 273                                         X509_REQ_free(req);
 274                                 }
 275                         }
 276
 277                         RSA_free(rsa);
 278                 }
 279
 280                 else {
 281                         lprintf(CTDL_CRIT, "Unable to read private key.\n");
 282                 }
 283         }
 284
 285
 286
 287         /*
 288          * Generate a self-signed certificate if we don't have one.
 289          */
 290         if (access(file_crpt_file_cer, R_OK) != 0) {
 291                 lprintf(CTDL_INFO, "Generating a self-signed certificate.\n");
 292
 293                 /* Same deal as before: always read the key from disk because
 294                  * it may or may not have just been generated.
 295                  */
 296                 fp = fopen(file_crpt_file_key, "r");
 297                 if (fp) {
 298                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 299                         fclose(fp);
 300                 }
 301
 302                 /* This also holds true for the CSR. */
 303                 req = NULL;
 304                 cer = NULL;
 305                 pk = NULL;
 306                 if (rsa) {
 307                         if (pk=EVP_PKEY_new(), pk != NULL) {
 308                                 EVP_PKEY_assign_RSA(pk, rsa);
 309                         }
 310
 311                         fp = fopen(file_crpt_file_csr, "r");
 312                         if (fp) {
 313                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 314                                 fclose(fp);
 315                         }
 316
 317                         if (req) {
 318                                 if (cer = X509_new(), cer != NULL) {
 319
 320                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 321                                         X509_set_issuer_name(cer, req->req_info->subject);
 322                                         X509_set_subject_name(cer, req->req_info->subject);
 323                                         X509_gmtime_adj(X509_get_notBefore(cer),0);
 324                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 325                                         req_pkey = X509_REQ_get_pubkey(req);
 326                                         X509_set_pubkey(cer, req_pkey);
 327                                         EVP_PKEY_free(req_pkey);
 328
 329                                         /* Sign the cert */
 330                                         if (!X509_sign(cer, pk, EVP_md5())) {
 331                                                 lprintf(CTDL_CRIT, "X509_sign(): error\n");
 332                                         }
 333                                         else {
 334                                                 /* Write it to disk. */
 335                                                 fp = fopen(file_crpt_file_cer, "w");
 336                                                 if (fp != NULL) {
 337                                                         chmod(file_crpt_file_cer, 0600);
 338                                                         PEM_write_X509(fp, cer);
 339                                                         fclose(fp);
 340                                                 }
 341                                         }
 342                                         X509_free(cer);
 343                                 }
 344                         }
 345
 346                         RSA_free(rsa);
 347                 }
 348         }
 349
 350
 351         /*
 352          * Now try to bind to the key and certificate.
 353          */
 354         SSL_CTX_use_certificate_chain_file(ssl_ctx, file_crpt_file_cer);
 355         SSL_CTX_use_PrivateKey_file(ssl_ctx, file_crpt_file_key, SSL_FILETYPE_PEM);
 356         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 357                 lprintf(CTDL_CRIT, "Cannot install certificate: %s\n",
 358                                 ERR_reason_error_string(ERR_get_error()));
 359         }
 360
 361         /* Finally let the server know we're here */
 362         CtdlRegisterProtoHook(cmd_stls, "STLS", "Start SSL/TLS session");
 363         CtdlRegisterProtoHook(cmd_gtls, "GTLS",
 364                               "Get SSL/TLS session status");
 365         CtdlRegisterSessionHook(endtls, EVT_STOP);
 366 }
 367
 368
 369 /*
 370  * client_write_ssl() Send binary data to the client encrypted.
 371  */
 372 void client_write_ssl(char *buf, int nbytes)
 373 {
 374         int retval;
 375         int nremain;
 376         char junk[1];
 377
 378         nremain = nbytes;
 379
 380         while (nremain > 0) {
 381                 if (SSL_want_write(CC->ssl)) {
 382                         if ((SSL_read(CC->ssl, junk, 0)) < 1) {
 383                                 lprintf(CTDL_DEBUG, "SSL_read in client_write: %s\n", ERR_reason_error_string(ERR_get_error()));
 384                         }
 385                 }
 386                 retval =
 387                     SSL_write(CC->ssl, &buf[nbytes - nremain], nremain);
 388                 if (retval < 1) {
 389                         long errval;
 390
 391                         errval = SSL_get_error(CC->ssl, retval);
 392                         if (errval == SSL_ERROR_WANT_READ ||
 393                             errval == SSL_ERROR_WANT_WRITE) {
 394                                 sleep(1);
 395                                 continue;
 396                         }
 397                         lprintf(CTDL_DEBUG, "SSL_write got error %ld, ret %d\n", errval, retval);
 398                         if (retval == -1)
 399                                 lprintf(CTDL_DEBUG, "errno is %d\n", errno);
 400                         endtls();
 401                         client_write(&buf[nbytes - nremain], nremain);
 402                         return;
 403                 }
 404                 nremain -= retval;
 405         }
 406 }
 407
 408
 409 /*
 410  * client_read_ssl() - read data from the encrypted layer.
 411  */
 412 int client_read_ssl(char *buf, int bytes, int timeout)
 413 {
 414 #if 0
 415         fd_set rfds;
 416         struct timeval tv;
 417         int retval;
 418         int s;
 419 #endif
 420         int len, rlen;
 421         char junk[1];
 422
 423         len = 0;
 424         while (len < bytes) {
 425 #if 0
 426                 /*
 427                  * This code is disabled because we don't need it when
 428                  * using blocking reads (which we are). -IO
 429                  */
 430                 FD_ZERO(&rfds);
 431                 s = BIO_get_fd(CC->ssl->rbio, NULL);
 432                 FD_SET(s, &rfds);
 433                 tv.tv_sec = timeout;
 434                 tv.tv_usec = 0;
 435
 436                 retval = select(s + 1, &rfds, NULL, NULL, &tv);
 437
 438                 if (FD_ISSET(s, &rfds) == 0) {
 439                         return (0);
 440                 }
 441
 442 #endif
 443                 if (SSL_want_read(CC->ssl)) {
 444                         if ((SSL_write(CC->ssl, junk, 0)) < 1) {
 445                                 lprintf(CTDL_DEBUG, "SSL_write in client_read: %s\n", ERR_reason_error_string(ERR_get_error()));
 446                         }
 447                 }
 448                 rlen = SSL_read(CC->ssl, &buf[len], bytes - len);
 449                 if (rlen < 1) {
 450                         long errval;
 451
 452                         errval = SSL_get_error(CC->ssl, rlen);
 453                         if (errval == SSL_ERROR_WANT_READ ||
 454                             errval == SSL_ERROR_WANT_WRITE) {
 455                                 sleep(1);
 456                                 continue;
 457                         }
 458                         lprintf(CTDL_DEBUG, "SSL_read got error %ld\n", errval);
 459                         endtls();
 460                         return (client_read_to
 461                                 (&buf[len], bytes - len, timeout));
 462                 }
 463                 len += rlen;
 464         }
 465         return (1);
 466 }
 467
 468
 469 /*
 470  * CtdlStartTLS() starts SSL/TLS encryption for the current session.  It
 471  * must be supplied with pre-generated strings for responses of "ok," "no
 472  * support for TLS," and "error" so that we can use this in any protocol.
 473  */
 474 void CtdlStartTLS(char *ok_response, char *nosup_response,
 475                         char *error_response) {
 476
 477         int retval, bits, alg_bits;
 478
 479         if (!ssl_ctx) {
 480                 lprintf(CTDL_CRIT, "SSL failed: no ssl_ctx exists?\n");
 481                 if (nosup_response != NULL) cprintf("%s", nosup_response);
 482                 return;
 483         }
 484         if (!(CC->ssl = SSL_new(ssl_ctx))) {
 485                 lprintf(CTDL_CRIT, "SSL_new failed: %s\n",
 486                                 ERR_reason_error_string(ERR_get_error()));
 487                 if (error_response != NULL) cprintf("%s", error_response);
 488                 return;
 489         }
 490         if (!(SSL_set_fd(CC->ssl, CC->client_socket))) {
 491                 lprintf(CTDL_CRIT, "SSL_set_fd failed: %s\n",
 492                         ERR_reason_error_string(ERR_get_error()));
 493                 SSL_free(CC->ssl);
 494                 CC->ssl = NULL;
 495                 if (error_response != NULL) cprintf("%s", error_response);
 496                 return;
 497         }
 498         if (ok_response != NULL) cprintf("%s", ok_response);
 499         retval = SSL_accept(CC->ssl);
 500         if (retval < 1) {
 501                 /*
 502                  * Can't notify the client of an error here; they will
 503                  * discover the problem at the SSL layer and should
 504                  * revert to unencrypted communications.
 505                  */
 506                 long errval;
 507                 char error_string[128];
 508
 509                 errval = SSL_get_error(CC->ssl, retval);
 510                 lprintf(CTDL_CRIT, "SSL_accept failed: retval=%d, errval=%ld, err=%s\n",
 511                         retval,
 512                         errval,
 513                         ERR_error_string(errval, error_string)
 514                 );
 515                 SSL_free(CC->ssl);
 516                 CC->ssl = NULL;
 517                 return;
 518         }
 519         BIO_set_close(CC->ssl->rbio, BIO_NOCLOSE);
 520         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl), &alg_bits);
 521         lprintf(CTDL_INFO, "SSL/TLS using %s on %s (%d of %d bits)\n",
 522                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 523                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 524                 bits, alg_bits);
 525         CC->redirect_ssl = 1;
 526 }
 527
 528
 529 /*
 530  * cmd_stls() starts SSL/TLS encryption for the current session
 531  */
 532 void cmd_stls(char *params)
 533 {
 534         char ok_response[SIZ];
 535         char nosup_response[SIZ];
 536         char error_response[SIZ];
 537
 538         unbuffer_output();
 539
 540         sprintf(ok_response,
 541                 "%d Begin TLS negotiation now\n",
 542                 CIT_OK);
 543         sprintf(nosup_response,
 544                 "%d TLS not supported here\n",
 545                 ERROR + CMD_NOT_SUPPORTED);
 546         sprintf(error_response,
 547                 "%d TLS negotiation error\n",
 548                 ERROR + INTERNAL_ERROR);
 549
 550         CtdlStartTLS(ok_response, nosup_response, error_response);
 551 }
 552
 553
 554 /*
 555  * cmd_gtls() returns status info about the TLS connection
 556  */
 557 void cmd_gtls(char *params)
 558 {
 559         int bits, alg_bits;
 560
 561         if (!CC->ssl || !CC->redirect_ssl) {
 562                 cprintf("%d Session is not encrypted.\n", ERROR);
 563                 return;
 564         }
 565         bits =
 566             SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl),
 567                                 &alg_bits);
 568         cprintf("%d %s|%s|%d|%d\n", CIT_OK,
 569                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 570                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 571                 alg_bits, bits);
 572 }
 573
 574
 575 /*
 576  * endtls() shuts down the TLS connection
 577  *
 578  * WARNING:  This may make your session vulnerable to a known plaintext
 579  * attack in the current implmentation.
 580  */
 581 void endtls(void)
 582 {
 583         if (!CC->ssl) {
 584                 CC->redirect_ssl = 0;
 585                 return;
 586         }
 587
 588         lprintf(CTDL_INFO, "Ending SSL/TLS\n");
 589         SSL_shutdown(CC->ssl);
 590         SSL_free(CC->ssl);
 591         CC->ssl = NULL;
 592         CC->redirect_ssl = 0;
 593 }
 594
 595
 596 /*
 597  * ssl_lock() callback for OpenSSL mutex locks
 598  */
 599 void ssl_lock(int mode, int n, const char *file, int line)
 600 {
 601         if (mode & CRYPTO_LOCK)
 602                 pthread_mutex_lock(SSLCritters[n]);
 603         else
 604                 pthread_mutex_unlock(SSLCritters[n]);
 605 }
 606 #endif                          /* HAVE_OPENSSL */