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