citadel/modules/crypto/serv_crypto.c

   1 /* $Id$
   2  *
   3  * Copyright (c) 1987-2009 by the citadel.org team
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 3 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to the Free Software
  17  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19
  20 #include <string.h>
  21 #include <unistd.h>
  22 #include <sys/stat.h>
  23 #include <sys/types.h>
  24 #include "sysdep.h"
  25
  26 #ifdef HAVE_OPENSSL
  27 #include <openssl/ssl.h>
  28 #include <openssl/err.h>
  29 #include <openssl/rand.h>
  30 #endif
  31
  32 #if TIME_WITH_SYS_TIME
  33 # include <sys/time.h>
  34 # include <time.h>
  35 #else
  36 # if HAVE_SYS_TIME_H
  37 #  include <sys/time.h>
  38 # else
  39 #  include <time.h>
  40 # endif
  41 #endif
  42
  43 #ifdef HAVE_PTHREAD_H
  44 #include <pthread.h>
  45 #endif
  46
  47 #ifdef HAVE_SYS_SELECT_H
  48 #include <sys/select.h>
  49 #endif
  50
  51 #include <stdio.h>
  52 #include <libcitadel.h>
  53 #include "server.h"
  54 #include "serv_crypto.h"
  55 #include "sysdep_decls.h"
  56 #include "citadel.h"
  57 #include "config.h"
  58
  59
  60 #include "ctdl_module.h"
  61 /* TODO: should we use the standard module init stuff to start this? */
  62 /* TODO: should we register an event handler to call destruct_ssl? */
  63
  64 #ifdef HAVE_OPENSSL
  65 SSL_CTX *ssl_ctx;               /* SSL context */
  66 pthread_mutex_t **SSLCritters;  /* Things needing locking */
  67
  68 static unsigned long id_callback(void)
  69 {
  70         return (unsigned long) pthread_self();
  71 }
  72
  73 void destruct_ssl(void)
  74 {
  75         int a;
  76         for (a = 0; a < CRYPTO_num_locks(); a++)
  77                 free(SSLCritters[a]);
  78         free (SSLCritters);
  79 }
  80
  81 void init_ssl(void)
  82 {
  83         SSL_METHOD *ssl_method;
  84         DH *dh;
  85         RSA *rsa=NULL;
  86         X509_REQ *req = NULL;
  87         X509 *cer = NULL;
  88         EVP_PKEY *pk = NULL;
  89         EVP_PKEY *req_pkey = NULL;
  90         X509_NAME *name = NULL;
  91         FILE *fp;
  92
  93         if (!access(EGD_POOL, F_OK))
  94                 RAND_egd(EGD_POOL);
  95
  96         if (!RAND_status()) {
  97                 CtdlLogPrintf(CTDL_CRIT,
  98                         "PRNG not adequately seeded, won't do SSL/TLS\n");
  99                 return;
 100         }
 101         SSLCritters =
 102             malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
 103         if (!SSLCritters) {
 104                 CtdlLogPrintf(CTDL_EMERG, "citserver: can't allocate memory!!\n");
 105                 /* Nothing's been initialized, just die */
 106                 exit(1);
 107         } else {
 108                 int a;
 109
 110                 for (a = 0; a < CRYPTO_num_locks(); a++) {
 111                         SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
 112                         if (!SSLCritters[a]) {
 113                                 CtdlLogPrintf(CTDL_EMERG,
 114                                         "citserver: can't allocate memory!!\n");
 115                                 /* Nothing's been initialized, just die */
 116                                 exit(1);
 117                         }
 118                         pthread_mutex_init(SSLCritters[a], NULL);
 119                 }
 120         }
 121
 122         /*
 123          * Initialize SSL transport layer
 124          */
 125         SSL_library_init();
 126         SSL_load_error_strings();
 127         ssl_method = SSLv23_server_method();
 128         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
 129                 CtdlLogPrintf(CTDL_CRIT, "SSL_CTX_new failed: %s\n",
 130                         ERR_reason_error_string(ERR_get_error()));
 131                 return;
 132         }
 133         if (!(SSL_CTX_set_cipher_list(ssl_ctx, CIT_CIPHERS))) {
 134                 CtdlLogPrintf(CTDL_CRIT, "SSL: No ciphers available\n");
 135                 SSL_CTX_free(ssl_ctx);
 136                 ssl_ctx = NULL;
 137                 return;
 138         }
 139 #if 0
 140 #if SSLEAY_VERSION_NUMBER >= 0x00906000L
 141         SSL_CTX_set_mode(ssl_ctx, SSL_CTX_get_mode(ssl_ctx) |
 142                          SSL_MODE_AUTO_RETRY);
 143 #endif
 144 #endif
 145
 146         CRYPTO_set_locking_callback(ssl_lock);
 147         CRYPTO_set_id_callback(id_callback);
 148
 149         /* Load DH parameters into the context */
 150         dh = DH_new();
 151         if (!dh) {
 152                 CtdlLogPrintf(CTDL_CRIT, "init_ssl() can't allocate a DH object: %s\n",
 153                         ERR_reason_error_string(ERR_get_error()));
 154                 SSL_CTX_free(ssl_ctx);
 155                 ssl_ctx = NULL;
 156                 return;
 157         }
 158         if (!(BN_hex2bn(&(dh->p), DH_P))) {
 159                 CtdlLogPrintf(CTDL_CRIT, "init_ssl() can't assign DH_P: %s\n",
 160                         ERR_reason_error_string(ERR_get_error()));
 161                 SSL_CTX_free(ssl_ctx);
 162                 ssl_ctx = NULL;
 163                 return;
 164         }
 165         if (!(BN_hex2bn(&(dh->g), DH_G))) {
 166                 CtdlLogPrintf(CTDL_CRIT, "init_ssl() can't assign DH_G: %s\n",
 167                         ERR_reason_error_string(ERR_get_error()));
 168                 SSL_CTX_free(ssl_ctx);
 169                 ssl_ctx = NULL;
 170                 return;
 171         }
 172         dh->length = DH_L;
 173         SSL_CTX_set_tmp_dh(ssl_ctx, dh);
 174         DH_free(dh);
 175
 176         /* Get our certificates in order.
 177          * First, create the key/cert directory if it's not there already...
 178          */
 179         mkdir(ctdl_key_dir, 0700);
 180
 181         /*
 182          * Generate a key pair if we don't have one.
 183          */
 184         if (access(file_crpt_file_key, R_OK) != 0) {
 185                 CtdlLogPrintf(CTDL_INFO, "Generating RSA key pair.\n");
 186                 rsa = RSA_generate_key(1024,    /* modulus size */
 187                                         65537,  /* exponent */
 188                                         NULL,   /* no callback */
 189                                         NULL);  /* no callback */
 190                 if (rsa == NULL) {
 191                         CtdlLogPrintf(CTDL_CRIT, "Key generation failed: %s\n",
 192                                 ERR_reason_error_string(ERR_get_error()));
 193                 }
 194                 if (rsa != NULL) {
 195                         fp = fopen(file_crpt_file_key, "w");
 196                         if (fp != NULL) {
 197                                 chmod(file_crpt_file_key, 0600);
 198                                 if (PEM_write_RSAPrivateKey(fp, /* the file */
 199                                                         rsa,    /* the key */
 200                                                         NULL,   /* no enc */
 201                                                         NULL,   /* no passphr */
 202                                                         0,      /* no passphr */
 203                                                         NULL,   /* no callbk */
 204                                                         NULL    /* no callbk */
 205                                 ) != 1) {
 206                                         CtdlLogPrintf(CTDL_CRIT, "Cannot write key: %s\n",
 207                                                 ERR_reason_error_string(ERR_get_error()));
 208                                         unlink(file_crpt_file_key);
 209                                 }
 210                                 fclose(fp);
 211                         }
 212                         RSA_free(rsa);
 213                 }
 214         }
 215
 216         /*
 217          * If there is no certificate file on disk, we will be generating a self-signed certificate
 218          * in the next step.  Therefore, if we have neither a CSR nor a certificate, generate
 219          * the CSR in this step so that the next step may commence.
 220          */
 221         if ( (access(file_crpt_file_cer, R_OK) != 0) && (access(file_crpt_file_csr, R_OK) != 0) ) {
 222                 CtdlLogPrintf(CTDL_INFO, "Generating a certificate signing request.\n");
 223
 224                 /*
 225                  * Read our key from the file.  No, we don't just keep this
 226                  * in memory from the above key-generation function, because
 227                  * there is the possibility that the key was already on disk
 228                  * and we didn't just generate it now.
 229                  */
 230                 fp = fopen(file_crpt_file_key, "r");
 231                 if (fp) {
 232                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 233                         fclose(fp);
 234                 }
 235
 236                 if (rsa) {
 237
 238                         /* Create a public key from the private key */
 239                         if (pk=EVP_PKEY_new(), pk != NULL) {
 240                                 EVP_PKEY_assign_RSA(pk, rsa);
 241                                 if (req = X509_REQ_new(), req != NULL) {
 242
 243                                         /* Set the public key */
 244                                         X509_REQ_set_pubkey(req, pk);
 245                                         X509_REQ_set_version(req, 0L);
 246
 247                                         name = X509_REQ_get_subject_name(req);
 248
 249                                         /* Tell it who we are */
 250
 251                                         /*
 252                                         X509_NAME_add_entry_by_txt(name, "C",
 253                                                 MBSTRING_ASC, "US", -1, -1, 0);
 254
 255                                         X509_NAME_add_entry_by_txt(name, "ST",
 256                                                 MBSTRING_ASC, "New York", -1, -1, 0);
 257
 258                                         X509_NAME_add_entry_by_txt(name, "L",
 259                                                 MBSTRING_ASC, "Mount Kisco", -1, -1, 0);
 260                                         */
 261
 262                                         X509_NAME_add_entry_by_txt(name, "O",
 263                                                 MBSTRING_ASC, config.c_humannode, -1, -1, 0);
 264
 265                                         X509_NAME_add_entry_by_txt(name, "OU",
 266                                                 MBSTRING_ASC, "Citadel server", -1, -1, 0);
 267
 268                                         /* X509_NAME_add_entry_by_txt(name, "CN",
 269                                                 MBSTRING_ASC, config.c_fqdn, -1, -1, 0);
 270                                         */
 271
 272                                         X509_NAME_add_entry_by_txt(name, "CN",
 273                                                 MBSTRING_ASC, "*", -1, -1, 0);
 274
 275                                         X509_REQ_set_subject_name(req, name);
 276
 277                                         /* Sign the CSR */
 278                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 279                                                 CtdlLogPrintf(CTDL_CRIT, "X509_REQ_sign(): error\n");
 280                                         }
 281                                         else {
 282                                                 /* Write it to disk. */
 283                                                 fp = fopen(file_crpt_file_csr, "w");
 284                                                 if (fp != NULL) {
 285                                                         chmod(file_crpt_file_csr, 0600);
 286                                                         PEM_write_X509_REQ(fp, req);
 287                                                         fclose(fp);
 288                                                 }
 289                                         }
 290
 291                                         X509_REQ_free(req);
 292                                 }
 293                         }
 294
 295                         RSA_free(rsa);
 296                 }
 297
 298                 else {
 299                         CtdlLogPrintf(CTDL_CRIT, "Unable to read private key.\n");
 300                 }
 301         }
 302
 303
 304
 305         /*
 306          * Generate a self-signed certificate if we don't have one.
 307          */
 308         if (access(file_crpt_file_cer, R_OK) != 0) {
 309                 CtdlLogPrintf(CTDL_INFO, "Generating a self-signed certificate.\n");
 310
 311                 /* Same deal as before: always read the key from disk because
 312                  * it may or may not have just been generated.
 313                  */
 314                 fp = fopen(file_crpt_file_key, "r");
 315                 if (fp) {
 316                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 317                         fclose(fp);
 318                 }
 319
 320                 /* This also holds true for the CSR. */
 321                 req = NULL;
 322                 cer = NULL;
 323                 pk = NULL;
 324                 if (rsa) {
 325                         if (pk=EVP_PKEY_new(), pk != NULL) {
 326                                 EVP_PKEY_assign_RSA(pk, rsa);
 327                         }
 328
 329                         fp = fopen(file_crpt_file_csr, "r");
 330                         if (fp) {
 331                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 332                                 fclose(fp);
 333                         }
 334
 335                         if (req) {
 336                                 if (cer = X509_new(), cer != NULL) {
 337
 338                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 339                                         X509_set_issuer_name(cer, req->req_info->subject);
 340                                         X509_set_subject_name(cer, req->req_info->subject);
 341                                         X509_gmtime_adj(X509_get_notBefore(cer),0);
 342                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 343                                         req_pkey = X509_REQ_get_pubkey(req);
 344                                         X509_set_pubkey(cer, req_pkey);
 345                                         EVP_PKEY_free(req_pkey);
 346
 347                                         /* Sign the cert */
 348                                         if (!X509_sign(cer, pk, EVP_md5())) {
 349                                                 CtdlLogPrintf(CTDL_CRIT, "X509_sign(): error\n");
 350                                         }
 351                                         else {
 352                                                 /* Write it to disk. */
 353                                                 fp = fopen(file_crpt_file_cer, "w");
 354                                                 if (fp != NULL) {
 355                                                         chmod(file_crpt_file_cer, 0600);
 356                                                         PEM_write_X509(fp, cer);
 357                                                         fclose(fp);
 358                                                 }
 359                                         }
 360                                         X509_free(cer);
 361                                 }
 362                         }
 363
 364                         RSA_free(rsa);
 365                 }
 366         }
 367
 368
 369         /*
 370          * Now try to bind to the key and certificate.
 371          */
 372         SSL_CTX_use_certificate_chain_file(ssl_ctx, file_crpt_file_cer);
 373         SSL_CTX_use_PrivateKey_file(ssl_ctx, file_crpt_file_key, SSL_FILETYPE_PEM);
 374         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 375                 CtdlLogPrintf(CTDL_CRIT, "Cannot install certificate: %s\n",
 376                                 ERR_reason_error_string(ERR_get_error()));
 377         }
 378
 379         /* Finally let the server know we're here */
 380         CtdlRegisterProtoHook(cmd_stls, "STLS", "Start SSL/TLS session");
 381         CtdlRegisterProtoHook(cmd_gtls, "GTLS",
 382                               "Get SSL/TLS session status");
 383         CtdlRegisterSessionHook(endtls, EVT_STOP);
 384 }
 385
 386
 387 /*
 388  * client_write_ssl() Send binary data to the client encrypted.
 389  */
 390 void client_write_ssl(char *buf, int nbytes)
 391 {
 392         int retval;
 393         int nremain;
 394         char junk[1];
 395
 396         nremain = nbytes;
 397
 398         while (nremain > 0) {
 399                 if (SSL_want_write(CC->ssl)) {
 400                         if ((SSL_read(CC->ssl, junk, 0)) < 1) {
 401                                 CtdlLogPrintf(CTDL_DEBUG, "SSL_read in client_write: %s\n", ERR_reason_error_string(ERR_get_error()));
 402                         }
 403                 }
 404                 retval =
 405                     SSL_write(CC->ssl, &buf[nbytes - nremain], nremain);
 406                 if (retval < 1) {
 407                         long errval;
 408
 409                         errval = SSL_get_error(CC->ssl, retval);
 410                         if (errval == SSL_ERROR_WANT_READ ||
 411                             errval == SSL_ERROR_WANT_WRITE) {
 412                                 sleep(1);
 413                                 continue;
 414                         }
 415                         CtdlLogPrintf(CTDL_DEBUG, "SSL_write got error %ld, ret %d\n", errval, retval);
 416                         if (retval == -1)
 417                                 CtdlLogPrintf(CTDL_DEBUG, "errno is %d\n", errno);
 418                         endtls();
 419                         client_write(&buf[nbytes - nremain], nremain);
 420                         return;
 421                 }
 422                 nremain -= retval;
 423         }
 424 }
 425
 426
 427 /*
 428  * client_read_ssl() - read data from the encrypted layer.
 429  */
 430 int client_read_ssl(char *buf, int bytes, int timeout)
 431 {
 432 #if 0
 433         fd_set rfds;
 434         struct timeval tv;
 435         int retval;
 436         int s;
 437 #endif
 438         int len, rlen;
 439         char junk[1];
 440
 441         len = 0;
 442         while (len < bytes) {
 443 #if 0
 444                 /*
 445                  * This code is disabled because we don't need it when
 446                  * using blocking reads (which we are). -IO
 447                  */
 448                 FD_ZERO(&rfds);
 449                 s = BIO_get_fd(CC->ssl->rbio, NULL);
 450                 FD_SET(s, &rfds);
 451                 tv.tv_sec = timeout;
 452                 tv.tv_usec = 0;
 453
 454                 retval = select(s + 1, &rfds, NULL, NULL, &tv);
 455
 456                 if (FD_ISSET(s, &rfds) == 0) {
 457                         return (0);
 458                 }
 459
 460 #endif
 461                 if (SSL_want_read(CC->ssl)) {
 462                         if ((SSL_write(CC->ssl, junk, 0)) < 1) {
 463                                 CtdlLogPrintf(CTDL_DEBUG, "SSL_write in client_read: %s\n", ERR_reason_error_string(ERR_get_error()));
 464                         }
 465                 }
 466                 rlen = SSL_read(CC->ssl, &buf[len], bytes - len);
 467                 if (rlen < 1) {
 468                         long errval;
 469
 470                         errval = SSL_get_error(CC->ssl, rlen);
 471                         if (errval == SSL_ERROR_WANT_READ ||
 472                             errval == SSL_ERROR_WANT_WRITE) {
 473                                 sleep(1);
 474                                 continue;
 475                         }
 476                         CtdlLogPrintf(CTDL_DEBUG, "SSL_read got error %ld\n", errval);
 477                         endtls();
 478                         return (client_read_to
 479                                 (&buf[len], bytes - len, timeout));
 480                 }
 481                 len += rlen;
 482         }
 483         return (1);
 484 }
 485
 486
 487 /*
 488  * CtdlStartTLS() starts SSL/TLS encryption for the current session.  It
 489  * must be supplied with pre-generated strings for responses of "ok," "no
 490  * support for TLS," and "error" so that we can use this in any protocol.
 491  */
 492 void CtdlStartTLS(char *ok_response, char *nosup_response,
 493                         char *error_response) {
 494
 495         int retval, bits, alg_bits;
 496
 497         if (!ssl_ctx) {
 498                 CtdlLogPrintf(CTDL_CRIT, "SSL failed: no ssl_ctx exists?\n");
 499                 if (nosup_response != NULL) cprintf("%s", nosup_response);
 500                 return;
 501         }
 502         if (!(CC->ssl = SSL_new(ssl_ctx))) {
 503                 CtdlLogPrintf(CTDL_CRIT, "SSL_new failed: %s\n",
 504                                 ERR_reason_error_string(ERR_get_error()));
 505                 if (error_response != NULL) cprintf("%s", error_response);
 506                 return;
 507         }
 508         if (!(SSL_set_fd(CC->ssl, CC->client_socket))) {
 509                 CtdlLogPrintf(CTDL_CRIT, "SSL_set_fd failed: %s\n",
 510                         ERR_reason_error_string(ERR_get_error()));
 511                 SSL_free(CC->ssl);
 512                 CC->ssl = NULL;
 513                 if (error_response != NULL) cprintf("%s", error_response);
 514                 return;
 515         }
 516         if (ok_response != NULL) cprintf("%s", ok_response);
 517         retval = SSL_accept(CC->ssl);
 518         if (retval < 1) {
 519                 /*
 520                  * Can't notify the client of an error here; they will
 521                  * discover the problem at the SSL layer and should
 522                  * revert to unencrypted communications.
 523                  */
 524                 long errval;
 525                 char error_string[128];
 526
 527                 errval = SSL_get_error(CC->ssl, retval);
 528                 CtdlLogPrintf(CTDL_CRIT, "SSL_accept failed: retval=%d, errval=%ld, err=%s\n",
 529                         retval,
 530                         errval,
 531                         ERR_error_string(errval, error_string)
 532                 );
 533                 SSL_free(CC->ssl);
 534                 CC->ssl = NULL;
 535                 return;
 536         }
 537         BIO_set_close(CC->ssl->rbio, BIO_NOCLOSE);
 538         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl), &alg_bits);
 539         CtdlLogPrintf(CTDL_INFO, "SSL/TLS using %s on %s (%d of %d bits)\n",
 540                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 541                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 542                 bits, alg_bits);
 543         CC->redirect_ssl = 1;
 544 }
 545
 546
 547 /*
 548  * cmd_stls() starts SSL/TLS encryption for the current session
 549  */
 550 void cmd_stls(char *params)
 551 {
 552         char ok_response[SIZ];
 553         char nosup_response[SIZ];
 554         char error_response[SIZ];
 555
 556         unbuffer_output();
 557
 558         sprintf(ok_response,
 559                 "%d Begin TLS negotiation now\n",
 560                 CIT_OK);
 561         sprintf(nosup_response,
 562                 "%d TLS not supported here\n",
 563                 ERROR + CMD_NOT_SUPPORTED);
 564         sprintf(error_response,
 565                 "%d TLS negotiation error\n",
 566                 ERROR + INTERNAL_ERROR);
 567
 568         CtdlStartTLS(ok_response, nosup_response, error_response);
 569 }
 570
 571
 572 /*
 573  * cmd_gtls() returns status info about the TLS connection
 574  */
 575 void cmd_gtls(char *params)
 576 {
 577         int bits, alg_bits;
 578
 579         if (!CC->ssl || !CC->redirect_ssl) {
 580                 cprintf("%d Session is not encrypted.\n", ERROR);
 581                 return;
 582         }
 583         bits =
 584             SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl),
 585                                 &alg_bits);
 586         cprintf("%d %s|%s|%d|%d\n", CIT_OK,
 587                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 588                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 589                 alg_bits, bits);
 590 }
 591
 592
 593 /*
 594  * endtls() shuts down the TLS connection
 595  *
 596  * WARNING:  This may make your session vulnerable to a known plaintext
 597  * attack in the current implmentation.
 598  */
 599 void endtls(void)
 600 {
 601         if (!CC->ssl) {
 602                 CC->redirect_ssl = 0;
 603                 return;
 604         }
 605
 606         CtdlLogPrintf(CTDL_INFO, "Ending SSL/TLS\n");
 607         SSL_shutdown(CC->ssl);
 608         SSL_free(CC->ssl);
 609         CC->ssl = NULL;
 610         CC->redirect_ssl = 0;
 611 }
 612
 613
 614 /*
 615  * ssl_lock() callback for OpenSSL mutex locks
 616  */
 617 void ssl_lock(int mode, int n, const char *file, int line)
 618 {
 619         if (mode & CRYPTO_LOCK)
 620                 pthread_mutex_lock(SSLCritters[n]);
 621         else
 622                 pthread_mutex_unlock(SSLCritters[n]);
 623 }
 624 #endif                          /* HAVE_OPENSSL */