citadel/modules/crypto/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 <libcitadel.h>
  36 #include "server.h"
  37 #include "serv_crypto.h"
  38 #include "sysdep_decls.h"
  39 #include "citadel.h"
  40 #include "config.h"
  41
  42
  43 #include "ctdl_module.h"
  44 /* TODO: should we use the standard module init stuff to start this? */
  45 /* TODO: should we register an event handler to call destruct_ssl? */
  46
  47 #ifdef HAVE_OPENSSL
  48 SSL_CTX *ssl_ctx;               /* SSL context */
  49 pthread_mutex_t **SSLCritters;  /* Things needing locking */
  50
  51 static unsigned long id_callback(void)
  52 {
  53         return (unsigned long) pthread_self();
  54 }
  55
  56 void destruct_ssl(void)
  57 {
  58         int a;
  59         CtdlUnregisterProtoHook(cmd_stls, "STLS");
  60         CtdlUnregisterProtoHook(cmd_gtls, "GTLS");
  61         for (a = 0; a < CRYPTO_num_locks(); a++)
  62                 free(SSLCritters[a]);
  63         free (SSLCritters);
  64 }
  65
  66 void init_ssl(void)
  67 {
  68         SSL_METHOD *ssl_method;
  69         DH *dh;
  70         RSA *rsa=NULL;
  71         X509_REQ *req = NULL;
  72         X509 *cer = NULL;
  73         EVP_PKEY *pk = NULL;
  74         EVP_PKEY *req_pkey = NULL;
  75         X509_NAME *name = NULL;
  76         FILE *fp;
  77
  78         if (!access(EGD_POOL, F_OK))
  79                 RAND_egd(EGD_POOL);
  80
  81         if (!RAND_status()) {
  82                 CtdlLogPrintf(CTDL_CRIT,
  83                         "PRNG not adequately seeded, won't do SSL/TLS\n");
  84                 return;
  85         }
  86         SSLCritters =
  87             malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
  88         if (!SSLCritters) {
  89                 CtdlLogPrintf(CTDL_EMERG, "citserver: can't allocate memory!!\n");
  90                 /* Nothing's been initialized, just die */
  91                 exit(1);
  92         } else {
  93                 int a;
  94
  95                 for (a = 0; a < CRYPTO_num_locks(); a++) {
  96                         SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
  97                         if (!SSLCritters[a]) {
  98                                 CtdlLogPrintf(CTDL_EMERG,
  99                                         "citserver: can't allocate memory!!\n");
 100                                 /* Nothing's been initialized, just die */
 101                                 exit(1);
 102                         }
 103                         pthread_mutex_init(SSLCritters[a], NULL);
 104                 }
 105         }
 106
 107         /*
 108          * Initialize SSL transport layer
 109          */
 110         SSL_library_init();
 111         SSL_load_error_strings();
 112         ssl_method = SSLv23_server_method();
 113         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
 114                 CtdlLogPrintf(CTDL_CRIT, "SSL_CTX_new failed: %s\n",
 115                         ERR_reason_error_string(ERR_get_error()));
 116                 return;
 117         }
 118         if (!(SSL_CTX_set_cipher_list(ssl_ctx, CIT_CIPHERS))) {
 119                 CtdlLogPrintf(CTDL_CRIT, "SSL: No ciphers available\n");
 120                 SSL_CTX_free(ssl_ctx);
 121                 ssl_ctx = NULL;
 122                 return;
 123         }
 124 #if 0
 125 #if SSLEAY_VERSION_NUMBER >= 0x00906000L
 126         SSL_CTX_set_mode(ssl_ctx, SSL_CTX_get_mode(ssl_ctx) |
 127                          SSL_MODE_AUTO_RETRY);
 128 #endif
 129 #endif
 130
 131         CRYPTO_set_locking_callback(ssl_lock);
 132         CRYPTO_set_id_callback(id_callback);
 133
 134         /* Load DH parameters into the context */
 135         dh = DH_new();
 136         if (!dh) {
 137                 CtdlLogPrintf(CTDL_CRIT, "init_ssl() can't allocate a DH object: %s\n",
 138                         ERR_reason_error_string(ERR_get_error()));
 139                 SSL_CTX_free(ssl_ctx);
 140                 ssl_ctx = NULL;
 141                 return;
 142         }
 143         if (!(BN_hex2bn(&(dh->p), DH_P))) {
 144                 CtdlLogPrintf(CTDL_CRIT, "init_ssl() can't assign DH_P: %s\n",
 145                         ERR_reason_error_string(ERR_get_error()));
 146                 SSL_CTX_free(ssl_ctx);
 147                 ssl_ctx = NULL;
 148                 return;
 149         }
 150         if (!(BN_hex2bn(&(dh->g), DH_G))) {
 151                 CtdlLogPrintf(CTDL_CRIT, "init_ssl() can't assign DH_G: %s\n",
 152                         ERR_reason_error_string(ERR_get_error()));
 153                 SSL_CTX_free(ssl_ctx);
 154                 ssl_ctx = NULL;
 155                 return;
 156         }
 157         dh->length = DH_L;
 158         SSL_CTX_set_tmp_dh(ssl_ctx, dh);
 159         DH_free(dh);
 160
 161         /* Get our certificates in order.
 162          * First, create the key/cert directory if it's not there already...
 163          */
 164         mkdir(ctdl_key_dir, 0700);
 165
 166         /*
 167          * Generate a key pair if we don't have one.
 168          */
 169         if (access(file_crpt_file_key, R_OK) != 0) {
 170                 CtdlLogPrintf(CTDL_INFO, "Generating RSA key pair.\n");
 171                 rsa = RSA_generate_key(1024,    /* modulus size */
 172                                         65537,  /* exponent */
 173                                         NULL,   /* no callback */
 174                                         NULL);  /* no callback */
 175                 if (rsa == NULL) {
 176                         CtdlLogPrintf(CTDL_CRIT, "Key generation failed: %s\n",
 177                                 ERR_reason_error_string(ERR_get_error()));
 178                 }
 179                 if (rsa != NULL) {
 180                         fp = fopen(file_crpt_file_key, "w");
 181                         if (fp != NULL) {
 182                                 chmod(file_crpt_file_key, 0600);
 183                                 if (PEM_write_RSAPrivateKey(fp, /* the file */
 184                                                         rsa,    /* the key */
 185                                                         NULL,   /* no enc */
 186                                                         NULL,   /* no passphr */
 187                                                         0,      /* no passphr */
 188                                                         NULL,   /* no callbk */
 189                                                         NULL    /* no callbk */
 190                                 ) != 1) {
 191                                         CtdlLogPrintf(CTDL_CRIT, "Cannot write key: %s\n",
 192                                                 ERR_reason_error_string(ERR_get_error()));
 193                                         unlink(file_crpt_file_key);
 194                                 }
 195                                 fclose(fp);
 196                         }
 197                         RSA_free(rsa);
 198                 }
 199         }
 200
 201         /*
 202          * If there is no certificate file on disk, we will be generating a self-signed certificate
 203          * in the next step.  Therefore, if we have neither a CSR nor a certificate, generate
 204          * the CSR in this step so that the next step may commence.
 205          */
 206         if ( (access(file_crpt_file_cer, R_OK) != 0) && (access(file_crpt_file_csr, R_OK) != 0) ) {
 207                 CtdlLogPrintf(CTDL_INFO, "Generating a certificate signing request.\n");
 208
 209                 /*
 210                  * Read our key from the file.  No, we don't just keep this
 211                  * in memory from the above key-generation function, because
 212                  * there is the possibility that the key was already on disk
 213                  * and we didn't just generate it now.
 214                  */
 215                 fp = fopen(file_crpt_file_key, "r");
 216                 if (fp) {
 217                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 218                         fclose(fp);
 219                 }
 220
 221                 if (rsa) {
 222
 223                         /* Create a public key from the private key */
 224                         if (pk=EVP_PKEY_new(), pk != NULL) {
 225                                 EVP_PKEY_assign_RSA(pk, rsa);
 226                                 if (req = X509_REQ_new(), req != NULL) {
 227
 228                                         /* Set the public key */
 229                                         X509_REQ_set_pubkey(req, pk);
 230                                         X509_REQ_set_version(req, 0L);
 231
 232                                         name = X509_REQ_get_subject_name(req);
 233
 234                                         /* Tell it who we are */
 235
 236                                         /*
 237                                         X509_NAME_add_entry_by_txt(name, "C",
 238                                                 MBSTRING_ASC, "US", -1, -1, 0);
 239
 240                                         X509_NAME_add_entry_by_txt(name, "ST",
 241                                                 MBSTRING_ASC, "New York", -1, -1, 0);
 242
 243                                         X509_NAME_add_entry_by_txt(name, "L",
 244                                                 MBSTRING_ASC, "Mount Kisco", -1, -1, 0);
 245                                         */
 246
 247                                         X509_NAME_add_entry_by_txt(name, "O",
 248                                                 MBSTRING_ASC, config.c_humannode, -1, -1, 0);
 249
 250                                         X509_NAME_add_entry_by_txt(name, "OU",
 251                                                 MBSTRING_ASC, "Citadel server", -1, -1, 0);
 252
 253                                         /* X509_NAME_add_entry_by_txt(name, "CN",
 254                                                 MBSTRING_ASC, config.c_fqdn, -1, -1, 0);
 255                                         */
 256
 257                                         X509_NAME_add_entry_by_txt(name, "CN",
 258                                                 MBSTRING_ASC, "*", -1, -1, 0);
 259
 260                                         X509_REQ_set_subject_name(req, name);
 261
 262                                         /* Sign the CSR */
 263                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 264                                                 CtdlLogPrintf(CTDL_CRIT, "X509_REQ_sign(): error\n");
 265                                         }
 266                                         else {
 267                                                 /* Write it to disk. */
 268                                                 fp = fopen(file_crpt_file_csr, "w");
 269                                                 if (fp != NULL) {
 270                                                         chmod(file_crpt_file_csr, 0600);
 271                                                         PEM_write_X509_REQ(fp, req);
 272                                                         fclose(fp);
 273                                                 }
 274                                         }
 275
 276                                         X509_REQ_free(req);
 277                                 }
 278                         }
 279
 280                         RSA_free(rsa);
 281                 }
 282
 283                 else {
 284                         CtdlLogPrintf(CTDL_CRIT, "Unable to read private key.\n");
 285                 }
 286         }
 287
 288
 289
 290         /*
 291          * Generate a self-signed certificate if we don't have one.
 292          */
 293         if (access(file_crpt_file_cer, R_OK) != 0) {
 294                 CtdlLogPrintf(CTDL_INFO, "Generating a self-signed certificate.\n");
 295
 296                 /* Same deal as before: always read the key from disk because
 297                  * it may or may not have just been generated.
 298                  */
 299                 fp = fopen(file_crpt_file_key, "r");
 300                 if (fp) {
 301                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 302                         fclose(fp);
 303                 }
 304
 305                 /* This also holds true for the CSR. */
 306                 req = NULL;
 307                 cer = NULL;
 308                 pk = NULL;
 309                 if (rsa) {
 310                         if (pk=EVP_PKEY_new(), pk != NULL) {
 311                                 EVP_PKEY_assign_RSA(pk, rsa);
 312                         }
 313
 314                         fp = fopen(file_crpt_file_csr, "r");
 315                         if (fp) {
 316                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 317                                 fclose(fp);
 318                         }
 319
 320                         if (req) {
 321                                 if (cer = X509_new(), cer != NULL) {
 322
 323                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 324                                         X509_set_issuer_name(cer, req->req_info->subject);
 325                                         X509_set_subject_name(cer, req->req_info->subject);
 326                                         X509_gmtime_adj(X509_get_notBefore(cer),0);
 327                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 328                                         req_pkey = X509_REQ_get_pubkey(req);
 329                                         X509_set_pubkey(cer, req_pkey);
 330                                         EVP_PKEY_free(req_pkey);
 331
 332                                         /* Sign the cert */
 333                                         if (!X509_sign(cer, pk, EVP_md5())) {
 334                                                 CtdlLogPrintf(CTDL_CRIT, "X509_sign(): error\n");
 335                                         }
 336                                         else {
 337                                                 /* Write it to disk. */
 338                                                 fp = fopen(file_crpt_file_cer, "w");
 339                                                 if (fp != NULL) {
 340                                                         chmod(file_crpt_file_cer, 0600);
 341                                                         PEM_write_X509(fp, cer);
 342                                                         fclose(fp);
 343                                                 }
 344                                         }
 345                                         X509_free(cer);
 346                                 }
 347                         }
 348
 349                         RSA_free(rsa);
 350                 }
 351         }
 352
 353
 354         /*
 355          * Now try to bind to the key and certificate.
 356          */
 357         SSL_CTX_use_certificate_chain_file(ssl_ctx, file_crpt_file_cer);
 358         SSL_CTX_use_PrivateKey_file(ssl_ctx, file_crpt_file_key, SSL_FILETYPE_PEM);
 359         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 360                 CtdlLogPrintf(CTDL_CRIT, "Cannot install certificate: %s\n",
 361                                 ERR_reason_error_string(ERR_get_error()));
 362         }
 363
 364         /* Finally let the server know we're here */
 365         CtdlRegisterProtoHook(cmd_stls, "STLS", "Start SSL/TLS session");
 366         CtdlRegisterProtoHook(cmd_gtls, "GTLS",
 367                               "Get SSL/TLS session status");
 368         CtdlRegisterSessionHook(endtls, EVT_STOP);
 369 }
 370
 371
 372 /*
 373  * client_write_ssl() Send binary data to the client encrypted.
 374  */
 375 void client_write_ssl(char *buf, int nbytes)
 376 {
 377         int retval;
 378         int nremain;
 379         char junk[1];
 380
 381         nremain = nbytes;
 382
 383         while (nremain > 0) {
 384                 if (SSL_want_write(CC->ssl)) {
 385                         if ((SSL_read(CC->ssl, junk, 0)) < 1) {
 386                                 CtdlLogPrintf(CTDL_DEBUG, "SSL_read in client_write: %s\n", ERR_reason_error_string(ERR_get_error()));
 387                         }
 388                 }
 389                 retval =
 390                     SSL_write(CC->ssl, &buf[nbytes - nremain], nremain);
 391                 if (retval < 1) {
 392                         long errval;
 393
 394                         errval = SSL_get_error(CC->ssl, retval);
 395                         if (errval == SSL_ERROR_WANT_READ ||
 396                             errval == SSL_ERROR_WANT_WRITE) {
 397                                 sleep(1);
 398                                 continue;
 399                         }
 400                         CtdlLogPrintf(CTDL_DEBUG, "SSL_write got error %ld, ret %d\n", errval, retval);
 401                         if (retval == -1)
 402                                 CtdlLogPrintf(CTDL_DEBUG, "errno is %d\n", errno);
 403                         endtls();
 404                         client_write(&buf[nbytes - nremain], nremain);
 405                         return;
 406                 }
 407                 nremain -= retval;
 408         }
 409 }
 410
 411
 412 /*
 413  * client_read_ssl() - read data from the encrypted layer.
 414  */
 415 int client_read_ssl(char *buf, int bytes, int timeout)
 416 {
 417 #if 0
 418         fd_set rfds;
 419         struct timeval tv;
 420         int retval;
 421         int s;
 422 #endif
 423         int len, rlen;
 424         char junk[1];
 425
 426         len = 0;
 427         while (len < bytes) {
 428 #if 0
 429                 /*
 430                  * This code is disabled because we don't need it when
 431                  * using blocking reads (which we are). -IO
 432                  */
 433                 FD_ZERO(&rfds);
 434                 s = BIO_get_fd(CC->ssl->rbio, NULL);
 435                 FD_SET(s, &rfds);
 436                 tv.tv_sec = timeout;
 437                 tv.tv_usec = 0;
 438
 439                 retval = select(s + 1, &rfds, NULL, NULL, &tv);
 440
 441                 if (FD_ISSET(s, &rfds) == 0) {
 442                         return (0);
 443                 }
 444
 445 #endif
 446                 if (SSL_want_read(CC->ssl)) {
 447                         if ((SSL_write(CC->ssl, junk, 0)) < 1) {
 448                                 CtdlLogPrintf(CTDL_DEBUG, "SSL_write in client_read: %s\n", ERR_reason_error_string(ERR_get_error()));
 449                         }
 450                 }
 451                 rlen = SSL_read(CC->ssl, &buf[len], bytes - len);
 452                 if (rlen < 1) {
 453                         long errval;
 454
 455                         errval = SSL_get_error(CC->ssl, rlen);
 456                         if (errval == SSL_ERROR_WANT_READ ||
 457                             errval == SSL_ERROR_WANT_WRITE) {
 458                                 sleep(1);
 459                                 continue;
 460                         }
 461                         CtdlLogPrintf(CTDL_DEBUG, "SSL_read got error %ld\n", errval);
 462                         endtls();
 463                         return (client_read_to
 464                                 (&buf[len], bytes - len, timeout));
 465                 }
 466                 len += rlen;
 467         }
 468         return (1);
 469 }
 470
 471
 472 /*
 473  * CtdlStartTLS() starts SSL/TLS encryption for the current session.  It
 474  * must be supplied with pre-generated strings for responses of "ok," "no
 475  * support for TLS," and "error" so that we can use this in any protocol.
 476  */
 477 void CtdlStartTLS(char *ok_response, char *nosup_response,
 478                         char *error_response) {
 479
 480         int retval, bits, alg_bits;
 481
 482         if (!ssl_ctx) {
 483                 CtdlLogPrintf(CTDL_CRIT, "SSL failed: no ssl_ctx exists?\n");
 484                 if (nosup_response != NULL) cprintf("%s", nosup_response);
 485                 return;
 486         }
 487         if (!(CC->ssl = SSL_new(ssl_ctx))) {
 488                 CtdlLogPrintf(CTDL_CRIT, "SSL_new failed: %s\n",
 489                                 ERR_reason_error_string(ERR_get_error()));
 490                 if (error_response != NULL) cprintf("%s", error_response);
 491                 return;
 492         }
 493         if (!(SSL_set_fd(CC->ssl, CC->client_socket))) {
 494                 CtdlLogPrintf(CTDL_CRIT, "SSL_set_fd failed: %s\n",
 495                         ERR_reason_error_string(ERR_get_error()));
 496                 SSL_free(CC->ssl);
 497                 CC->ssl = NULL;
 498                 if (error_response != NULL) cprintf("%s", error_response);
 499                 return;
 500         }
 501         if (ok_response != NULL) cprintf("%s", ok_response);
 502         retval = SSL_accept(CC->ssl);
 503         if (retval < 1) {
 504                 /*
 505                  * Can't notify the client of an error here; they will
 506                  * discover the problem at the SSL layer and should
 507                  * revert to unencrypted communications.
 508                  */
 509                 long errval;
 510                 char error_string[128];
 511
 512                 errval = SSL_get_error(CC->ssl, retval);
 513                 CtdlLogPrintf(CTDL_CRIT, "SSL_accept failed: retval=%d, errval=%ld, err=%s\n",
 514                         retval,
 515                         errval,
 516                         ERR_error_string(errval, error_string)
 517                 );
 518                 SSL_free(CC->ssl);
 519                 CC->ssl = NULL;
 520                 return;
 521         }
 522         BIO_set_close(CC->ssl->rbio, BIO_NOCLOSE);
 523         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl), &alg_bits);
 524         CtdlLogPrintf(CTDL_INFO, "SSL/TLS using %s on %s (%d of %d bits)\n",
 525                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 526                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 527                 bits, alg_bits);
 528         CC->redirect_ssl = 1;
 529 }
 530
 531
 532 /*
 533  * cmd_stls() starts SSL/TLS encryption for the current session
 534  */
 535 void cmd_stls(char *params)
 536 {
 537         char ok_response[SIZ];
 538         char nosup_response[SIZ];
 539         char error_response[SIZ];
 540
 541         unbuffer_output();
 542
 543         sprintf(ok_response,
 544                 "%d Begin TLS negotiation now\n",
 545                 CIT_OK);
 546         sprintf(nosup_response,
 547                 "%d TLS not supported here\n",
 548                 ERROR + CMD_NOT_SUPPORTED);
 549         sprintf(error_response,
 550                 "%d TLS negotiation error\n",
 551                 ERROR + INTERNAL_ERROR);
 552
 553         CtdlStartTLS(ok_response, nosup_response, error_response);
 554 }
 555
 556
 557 /*
 558  * cmd_gtls() returns status info about the TLS connection
 559  */
 560 void cmd_gtls(char *params)
 561 {
 562         int bits, alg_bits;
 563
 564         if (!CC->ssl || !CC->redirect_ssl) {
 565                 cprintf("%d Session is not encrypted.\n", ERROR);
 566                 return;
 567         }
 568         bits =
 569             SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl),
 570                                 &alg_bits);
 571         cprintf("%d %s|%s|%d|%d\n", CIT_OK,
 572                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 573                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 574                 alg_bits, bits);
 575 }
 576
 577
 578 /*
 579  * endtls() shuts down the TLS connection
 580  *
 581  * WARNING:  This may make your session vulnerable to a known plaintext
 582  * attack in the current implmentation.
 583  */
 584 void endtls(void)
 585 {
 586         if (!CC->ssl) {
 587                 CC->redirect_ssl = 0;
 588                 return;
 589         }
 590
 591         CtdlLogPrintf(CTDL_INFO, "Ending SSL/TLS\n");
 592         SSL_shutdown(CC->ssl);
 593         SSL_free(CC->ssl);
 594         CC->ssl = NULL;
 595         CC->redirect_ssl = 0;
 596 }
 597
 598
 599 /*
 600  * ssl_lock() callback for OpenSSL mutex locks
 601  */
 602 void ssl_lock(int mode, int n, const char *file, int line)
 603 {
 604         if (mode & CRYPTO_LOCK)
 605                 pthread_mutex_lock(SSLCritters[n]);
 606         else
 607                 pthread_mutex_unlock(SSLCritters[n]);
 608 }
 609 #endif                          /* HAVE_OPENSSL */