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