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 "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                 CtdlLogPrintf(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                 CtdlLogPrintf(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                                 CtdlLogPrintf(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                 CtdlLogPrintf(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                 CtdlLogPrintf(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                 CtdlLogPrintf(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                 CtdlLogPrintf(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                 CtdlLogPrintf(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                 CtdlLogPrintf(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                         CtdlLogPrintf(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                                         CtdlLogPrintf(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          * If there is no certificate file on disk, we will be generating a self-signed certificate
 202          * in the next step.  Therefore, if we have neither a CSR nor a certificate, generate
 203          * the CSR in this step so that the next step may commence.
 204          */
 205         if ( (access(file_crpt_file_cer, R_OK) != 0) && (access(file_crpt_file_csr, R_OK) != 0) ) {
 206                 CtdlLogPrintf(CTDL_INFO, "Generating a certificate signing request.\n");
 207
 208                 /*
 209                  * Read our key from the file.  No, we don't just keep this
 210                  * in memory from the above key-generation function, because
 211                  * there is the possibility that the key was already on disk
 212                  * and we didn't just generate it now.
 213                  */
 214                 fp = fopen(file_crpt_file_key, "r");
 215                 if (fp) {
 216                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 217                         fclose(fp);
 218                 }
 219
 220                 if (rsa) {
 221
 222                         /* Create a public key from the private key */
 223                         if (pk=EVP_PKEY_new(), pk != NULL) {
 224                                 EVP_PKEY_assign_RSA(pk, rsa);
 225                                 if (req = X509_REQ_new(), req != NULL) {
 226
 227                                         /* Set the public key */
 228                                         X509_REQ_set_pubkey(req, pk);
 229                                         X509_REQ_set_version(req, 0L);
 230
 231                                         name = X509_REQ_get_subject_name(req);
 232
 233                                         /* Tell it who we are */
 234
 235                                         /*
 236                                         X509_NAME_add_entry_by_txt(name, "C",
 237                                                 MBSTRING_ASC, "US", -1, -1, 0);
 238
 239                                         X509_NAME_add_entry_by_txt(name, "ST",
 240                                                 MBSTRING_ASC, "New York", -1, -1, 0);
 241
 242                                         X509_NAME_add_entry_by_txt(name, "L",
 243                                                 MBSTRING_ASC, "Mount Kisco", -1, -1, 0);
 244                                         */
 245
 246                                         X509_NAME_add_entry_by_txt(name, "O",
 247                                                 MBSTRING_ASC, config.c_humannode, -1, -1, 0);
 248
 249                                         X509_NAME_add_entry_by_txt(name, "OU",
 250                                                 MBSTRING_ASC, "Citadel server", -1, -1, 0);
 251
 252                                         /* X509_NAME_add_entry_by_txt(name, "CN",
 253                                                 MBSTRING_ASC, config.c_fqdn, -1, -1, 0);
 254                                         */
 255
 256                                         X509_NAME_add_entry_by_txt(name, "CN",
 257                                                 MBSTRING_ASC, "*", -1, -1, 0);
 258
 259                                         X509_REQ_set_subject_name(req, name);
 260
 261                                         /* Sign the CSR */
 262                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 263                                                 CtdlLogPrintf(CTDL_CRIT, "X509_REQ_sign(): error\n");
 264                                         }
 265                                         else {
 266                                                 /* Write it to disk. */
 267                                                 fp = fopen(file_crpt_file_csr, "w");
 268                                                 if (fp != NULL) {
 269                                                         chmod(file_crpt_file_csr, 0600);
 270                                                         PEM_write_X509_REQ(fp, req);
 271                                                         fclose(fp);
 272                                                 }
 273                                         }
 274
 275                                         X509_REQ_free(req);
 276                                 }
 277                         }
 278
 279                         RSA_free(rsa);
 280                 }
 281
 282                 else {
 283                         CtdlLogPrintf(CTDL_CRIT, "Unable to read private key.\n");
 284                 }
 285         }
 286
 287
 288
 289         /*
 290          * Generate a self-signed certificate if we don't have one.
 291          */
 292         if (access(file_crpt_file_cer, R_OK) != 0) {
 293                 CtdlLogPrintf(CTDL_INFO, "Generating a self-signed certificate.\n");
 294
 295                 /* Same deal as before: always read the key from disk because
 296                  * it may or may not have just been generated.
 297                  */
 298                 fp = fopen(file_crpt_file_key, "r");
 299                 if (fp) {
 300                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 301                         fclose(fp);
 302                 }
 303
 304                 /* This also holds true for the CSR. */
 305                 req = NULL;
 306                 cer = NULL;
 307                 pk = NULL;
 308                 if (rsa) {
 309                         if (pk=EVP_PKEY_new(), pk != NULL) {
 310                                 EVP_PKEY_assign_RSA(pk, rsa);
 311                         }
 312
 313                         fp = fopen(file_crpt_file_csr, "r");
 314                         if (fp) {
 315                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 316                                 fclose(fp);
 317                         }
 318
 319                         if (req) {
 320                                 if (cer = X509_new(), cer != NULL) {
 321
 322                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 323                                         X509_set_issuer_name(cer, req->req_info->subject);
 324                                         X509_set_subject_name(cer, req->req_info->subject);
 325                                         X509_gmtime_adj(X509_get_notBefore(cer),0);
 326                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 327                                         req_pkey = X509_REQ_get_pubkey(req);
 328                                         X509_set_pubkey(cer, req_pkey);
 329                                         EVP_PKEY_free(req_pkey);
 330
 331                                         /* Sign the cert */
 332                                         if (!X509_sign(cer, pk, EVP_md5())) {
 333                                                 CtdlLogPrintf(CTDL_CRIT, "X509_sign(): error\n");
 334                                         }
 335                                         else {
 336                                                 /* Write it to disk. */
 337                                                 fp = fopen(file_crpt_file_cer, "w");
 338                                                 if (fp != NULL) {
 339                                                         chmod(file_crpt_file_cer, 0600);
 340                                                         PEM_write_X509(fp, cer);
 341                                                         fclose(fp);
 342                                                 }
 343                                         }
 344                                         X509_free(cer);
 345                                 }
 346                         }
 347
 348                         RSA_free(rsa);
 349                 }
 350         }
 351
 352
 353         /*
 354          * Now try to bind to the key and certificate.
 355          */
 356         SSL_CTX_use_certificate_chain_file(ssl_ctx, file_crpt_file_cer);
 357         SSL_CTX_use_PrivateKey_file(ssl_ctx, file_crpt_file_key, SSL_FILETYPE_PEM);
 358         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 359                 CtdlLogPrintf(CTDL_CRIT, "Cannot install certificate: %s\n",
 360                                 ERR_reason_error_string(ERR_get_error()));
 361         }
 362
 363         /* Finally let the server know we're here */
 364         CtdlRegisterProtoHook(cmd_stls, "STLS", "Start SSL/TLS session");
 365         CtdlRegisterProtoHook(cmd_gtls, "GTLS",
 366                               "Get SSL/TLS session status");
 367         CtdlRegisterSessionHook(endtls, EVT_STOP);
 368 }
 369
 370
 371 /*
 372  * client_write_ssl() Send binary data to the client encrypted.
 373  */
 374 void client_write_ssl(char *buf, int nbytes)
 375 {
 376         int retval;
 377         int nremain;
 378         char junk[1];
 379
 380         nremain = nbytes;
 381
 382         while (nremain > 0) {
 383                 if (SSL_want_write(CC->ssl)) {
 384                         if ((SSL_read(CC->ssl, junk, 0)) < 1) {
 385                                 CtdlLogPrintf(CTDL_DEBUG, "SSL_read in client_write: %s\n", ERR_reason_error_string(ERR_get_error()));
 386                         }
 387                 }
 388                 retval =
 389                     SSL_write(CC->ssl, &buf[nbytes - nremain], nremain);
 390                 if (retval < 1) {
 391                         long errval;
 392
 393                         errval = SSL_get_error(CC->ssl, retval);
 394                         if (errval == SSL_ERROR_WANT_READ ||
 395                             errval == SSL_ERROR_WANT_WRITE) {
 396                                 sleep(1);
 397                                 continue;
 398                         }
 399                         CtdlLogPrintf(CTDL_DEBUG, "SSL_write got error %ld, ret %d\n", errval, retval);
 400                         if (retval == -1)
 401                                 CtdlLogPrintf(CTDL_DEBUG, "errno is %d\n", errno);
 402                         endtls();
 403                         client_write(&buf[nbytes - nremain], nremain);
 404                         return;
 405                 }
 406                 nremain -= retval;
 407         }
 408 }
 409
 410
 411 /*
 412  * client_read_ssl() - read data from the encrypted layer.
 413  */
 414 int client_read_ssl(char *buf, int bytes, int timeout)
 415 {
 416 #if 0
 417         fd_set rfds;
 418         struct timeval tv;
 419         int retval;
 420         int s;
 421 #endif
 422         int len, rlen;
 423         char junk[1];
 424
 425         len = 0;
 426         while (len < bytes) {
 427 #if 0
 428                 /*
 429                  * This code is disabled because we don't need it when
 430                  * using blocking reads (which we are). -IO
 431                  */
 432                 FD_ZERO(&rfds);
 433                 s = BIO_get_fd(CC->ssl->rbio, NULL);
 434                 FD_SET(s, &rfds);
 435                 tv.tv_sec = timeout;
 436                 tv.tv_usec = 0;
 437
 438                 retval = select(s + 1, &rfds, NULL, NULL, &tv);
 439
 440                 if (FD_ISSET(s, &rfds) == 0) {
 441                         return (0);
 442                 }
 443
 444 #endif
 445                 if (SSL_want_read(CC->ssl)) {
 446                         if ((SSL_write(CC->ssl, junk, 0)) < 1) {
 447                                 CtdlLogPrintf(CTDL_DEBUG, "SSL_write in client_read: %s\n", ERR_reason_error_string(ERR_get_error()));
 448                         }
 449                 }
 450                 rlen = SSL_read(CC->ssl, &buf[len], bytes - len);
 451                 if (rlen < 1) {
 452                         long errval;
 453
 454                         errval = SSL_get_error(CC->ssl, rlen);
 455                         if (errval == SSL_ERROR_WANT_READ ||
 456                             errval == SSL_ERROR_WANT_WRITE) {
 457                                 sleep(1);
 458                                 continue;
 459                         }
 460                         CtdlLogPrintf(CTDL_DEBUG, "SSL_read got error %ld\n", errval);
 461                         endtls();
 462                         return (client_read_to
 463                                 (&buf[len], bytes - len, timeout));
 464                 }
 465                 len += rlen;
 466         }
 467         return (1);
 468 }
 469
 470
 471 /*
 472  * CtdlStartTLS() starts SSL/TLS encryption for the current session.  It
 473  * must be supplied with pre-generated strings for responses of "ok," "no
 474  * support for TLS," and "error" so that we can use this in any protocol.
 475  */
 476 void CtdlStartTLS(char *ok_response, char *nosup_response,
 477                         char *error_response) {
 478
 479         int retval, bits, alg_bits;
 480
 481         if (!ssl_ctx) {
 482                 CtdlLogPrintf(CTDL_CRIT, "SSL failed: no ssl_ctx exists?\n");
 483                 if (nosup_response != NULL) cprintf("%s", nosup_response);
 484                 return;
 485         }
 486         if (!(CC->ssl = SSL_new(ssl_ctx))) {
 487                 CtdlLogPrintf(CTDL_CRIT, "SSL_new failed: %s\n",
 488                                 ERR_reason_error_string(ERR_get_error()));
 489                 if (error_response != NULL) cprintf("%s", error_response);
 490                 return;
 491         }
 492         if (!(SSL_set_fd(CC->ssl, CC->client_socket))) {
 493                 CtdlLogPrintf(CTDL_CRIT, "SSL_set_fd failed: %s\n",
 494                         ERR_reason_error_string(ERR_get_error()));
 495                 SSL_free(CC->ssl);
 496                 CC->ssl = NULL;
 497                 if (error_response != NULL) cprintf("%s", error_response);
 498                 return;
 499         }
 500         if (ok_response != NULL) cprintf("%s", ok_response);
 501         retval = SSL_accept(CC->ssl);
 502         if (retval < 1) {
 503                 /*
 504                  * Can't notify the client of an error here; they will
 505                  * discover the problem at the SSL layer and should
 506                  * revert to unencrypted communications.
 507                  */
 508                 long errval;
 509                 char error_string[128];
 510
 511                 errval = SSL_get_error(CC->ssl, retval);
 512                 CtdlLogPrintf(CTDL_CRIT, "SSL_accept failed: retval=%d, errval=%ld, err=%s\n",
 513                         retval,
 514                         errval,
 515                         ERR_error_string(errval, error_string)
 516                 );
 517                 SSL_free(CC->ssl);
 518                 CC->ssl = NULL;
 519                 return;
 520         }
 521         BIO_set_close(CC->ssl->rbio, BIO_NOCLOSE);
 522         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl), &alg_bits);
 523         CtdlLogPrintf(CTDL_INFO, "SSL/TLS using %s on %s (%d of %d bits)\n",
 524                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 525                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 526                 bits, alg_bits);
 527         CC->redirect_ssl = 1;
 528 }
 529
 530
 531 /*
 532  * cmd_stls() starts SSL/TLS encryption for the current session
 533  */
 534 void cmd_stls(char *params)
 535 {
 536         char ok_response[SIZ];
 537         char nosup_response[SIZ];
 538         char error_response[SIZ];
 539
 540         unbuffer_output();
 541
 542         sprintf(ok_response,
 543                 "%d Begin TLS negotiation now\n",
 544                 CIT_OK);
 545         sprintf(nosup_response,
 546                 "%d TLS not supported here\n",
 547                 ERROR + CMD_NOT_SUPPORTED);
 548         sprintf(error_response,
 549                 "%d TLS negotiation error\n",
 550                 ERROR + INTERNAL_ERROR);
 551
 552         CtdlStartTLS(ok_response, nosup_response, error_response);
 553 }
 554
 555
 556 /*
 557  * cmd_gtls() returns status info about the TLS connection
 558  */
 559 void cmd_gtls(char *params)
 560 {
 561         int bits, alg_bits;
 562
 563         if (!CC->ssl || !CC->redirect_ssl) {
 564                 cprintf("%d Session is not encrypted.\n", ERROR);
 565                 return;
 566         }
 567         bits =
 568             SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl),
 569                                 &alg_bits);
 570         cprintf("%d %s|%s|%d|%d\n", CIT_OK,
 571                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 572                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 573                 alg_bits, bits);
 574 }
 575
 576
 577 /*
 578  * endtls() shuts down the TLS connection
 579  *
 580  * WARNING:  This may make your session vulnerable to a known plaintext
 581  * attack in the current implmentation.
 582  */
 583 void endtls(void)
 584 {
 585         if (!CC->ssl) {
 586                 CC->redirect_ssl = 0;
 587                 return;
 588         }
 589
 590         CtdlLogPrintf(CTDL_INFO, "Ending SSL/TLS\n");
 591         SSL_shutdown(CC->ssl);
 592         SSL_free(CC->ssl);
 593         CC->ssl = NULL;
 594         CC->redirect_ssl = 0;
 595 }
 596
 597
 598 /*
 599  * ssl_lock() callback for OpenSSL mutex locks
 600  */
 601 void ssl_lock(int mode, int n, const char *file, int line)
 602 {
 603         if (mode & CRYPTO_LOCK)
 604                 pthread_mutex_lock(SSLCritters[n]);
 605         else
 606                 pthread_mutex_unlock(SSLCritters[n]);
 607 }
 608 #endif                          /* HAVE_OPENSSL */