citadel/modules/crypto/serv_crypto.c

   1 /*
   2  * Copyright (c) 1987-2015 by the citadel.org team
   3  *
   4  * This program is open source software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 3.
   6  *
   7  * This program is distributed in the hope that it will be useful,
   8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  * GNU General Public License for more details.
  11  */
  12
  13 #include <string.h>
  14 #include <unistd.h>
  15 #include <sys/stat.h>
  16 #include <sys/types.h>
  17 #include "sysdep.h"
  18
  19 #ifdef HAVE_OPENSSL
  20 #include <openssl/ssl.h>
  21 #include <openssl/err.h>
  22 #include <openssl/rand.h>
  23 #endif
  24
  25 #if TIME_WITH_SYS_TIME
  26 # include <sys/time.h>
  27 # include <time.h>
  28 #else
  29 # if HAVE_SYS_TIME_H
  30 #  include <sys/time.h>
  31 # else
  32 #  include <time.h>
  33 # endif
  34 #endif
  35
  36 #ifdef HAVE_PTHREAD_H
  37 #include <pthread.h>
  38 #endif
  39
  40 #ifdef HAVE_SYS_SELECT_H
  41 #include <sys/select.h>
  42 #endif
  43
  44 #include <stdio.h>
  45 #include <libcitadel.h>
  46 #include "server.h"
  47 #include "serv_crypto.h"
  48 #include "sysdep_decls.h"
  49 #include "citadel.h"
  50 #include "config.h"
  51
  52
  53 #include "ctdl_module.h"
  54 /* TODO: should we use the standard module init stuff to start this? */
  55 /* TODO: should we register an event handler to call destruct_ssl? */
  56
  57 #ifdef HAVE_OPENSSL
  58 SSL_CTX *ssl_ctx;               /* SSL context */
  59 pthread_mutex_t **SSLCritters;  /* Things needing locking */
  60
  61 static unsigned long id_callback(void)
  62 {
  63         return (unsigned long) pthread_self();
  64 }
  65
  66 void destruct_ssl(void)
  67 {
  68         int a;
  69         for (a = 0; a < CRYPTO_num_locks(); a++)
  70                 free(SSLCritters[a]);
  71         free (SSLCritters);
  72 }
  73
  74 void init_ssl(void)
  75 {
  76         const SSL_METHOD *ssl_method;
  77         RSA *rsa=NULL;
  78         X509_REQ *req = NULL;
  79         X509 *cer = NULL;
  80         EVP_PKEY *pk = NULL;
  81         EVP_PKEY *req_pkey = NULL;
  82         X509_NAME *name = NULL;
  83         FILE *fp;
  84
  85         if (!access(EGD_POOL, F_OK))
  86                 RAND_egd(EGD_POOL);
  87
  88         if (!RAND_status()) {
  89                 syslog(LOG_CRIT, "PRNG not adequately seeded, won't do SSL/TLS");
  90                 return;
  91         }
  92         SSLCritters =
  93             malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
  94         if (!SSLCritters) {
  95                 syslog(LOG_EMERG, "citserver: can't allocate memory!!");
  96                 /* Nothing's been initialized, just die */
  97                 exit(1);
  98         } else {
  99                 int a;
 100
 101                 for (a = 0; a < CRYPTO_num_locks(); a++) {
 102                         SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
 103                         if (!SSLCritters[a]) {
 104                                 syslog(LOG_EMERG, "citserver: can't allocate memory!!");
 105                                 /* Nothing's been initialized, just die */
 106                                 exit(1);
 107                         }
 108                         pthread_mutex_init(SSLCritters[a], NULL);
 109                 }
 110         }
 111
 112         /*
 113          * Initialize SSL transport layer
 114          */
 115         SSL_library_init();
 116         SSL_load_error_strings();
 117         ssl_method = SSLv23_server_method();
 118         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
 119                 syslog(LOG_CRIT, "SSL_CTX_new failed: %s", ERR_reason_error_string(ERR_get_error()));
 120                 return;
 121         }
 122         if (!(SSL_CTX_set_cipher_list(ssl_ctx, CIT_CIPHERS))) {
 123                 syslog(LOG_CRIT, "SSL: No ciphers available");
 124                 SSL_CTX_free(ssl_ctx);
 125                 ssl_ctx = NULL;
 126                 return;
 127         }
 128 #if 0
 129 #if SSLEAY_VERSION_NUMBER >= 0x00906000L
 130         SSL_CTX_set_mode(ssl_ctx, SSL_CTX_get_mode(ssl_ctx) |
 131                          SSL_MODE_AUTO_RETRY);
 132 #endif
 133 #endif
 134
 135         CRYPTO_set_locking_callback(ssl_lock);
 136         CRYPTO_set_id_callback(id_callback);
 137
 138 #if 0 // this doesn't work in newer openssl
 139         /* Load DH parameters into the context */
 140         DH *dh = DH_new();
 141         if (!dh) {
 142                 syslog(LOG_CRIT, "init_ssl() can't allocate a DH object: %s", ERR_reason_error_string(ERR_get_error()));
 143                 SSL_CTX_free(ssl_ctx);
 144                 ssl_ctx = NULL;
 145                 return;
 146         }
 147         if (!(BN_hex2bn(&(dh->p), DH_P))) {
 148                 syslog(LOG_CRIT, "init_ssl() can't assign DH_P: %s", ERR_reason_error_string(ERR_get_error()));
 149                 SSL_CTX_free(ssl_ctx);
 150                 ssl_ctx = NULL;
 151                 return;
 152         }
 153         if (!(BN_hex2bn(&(dh->g), DH_G))) {
 154                 syslog(LOG_CRIT, "init_ssl() can't assign DH_G: %s", ERR_reason_error_string(ERR_get_error()));
 155                 SSL_CTX_free(ssl_ctx);
 156                 ssl_ctx = NULL;
 157                 return;
 158         }
 159         dh->length = DH_L;
 160         SSL_CTX_set_tmp_dh(ssl_ctx, dh);
 161         DH_free(dh);
 162 #endif // this doesn't work in newer openssl
 163
 164         /* Get our certificates in order.
 165          * First, create the key/cert directory if it's not there already...
 166          */
 167         mkdir(ctdl_key_dir, 0700);
 168
 169         /*
 170          * Generate a key pair if we don't have one.
 171          */
 172         if (access(file_crpt_file_key, R_OK) != 0) {
 173                 syslog(LOG_INFO, "Generating RSA key pair.");
 174                 rsa = RSA_generate_key(1024,    /* modulus size */
 175                                         65537,  /* exponent */
 176                                         NULL,   /* no callback */
 177                                         NULL);  /* no callback */
 178                 if (rsa == NULL) {
 179                         syslog(LOG_CRIT, "Key generation failed: %s", ERR_reason_error_string(ERR_get_error()));
 180                 }
 181                 if (rsa != NULL) {
 182                         fp = fopen(file_crpt_file_key, "w");
 183                         if (fp != NULL) {
 184                                 chmod(file_crpt_file_key, 0600);
 185                                 if (PEM_write_RSAPrivateKey(fp, /* the file */
 186                                                         rsa,    /* the key */
 187                                                         NULL,   /* no enc */
 188                                                         NULL,   /* no passphr */
 189                                                         0,      /* no passphr */
 190                                                         NULL,   /* no callbk */
 191                                                         NULL    /* no callbk */
 192                                 ) != 1) {
 193                                         syslog(LOG_CRIT, "Cannot write key: %s", ERR_reason_error_string(ERR_get_error()));
 194                                         unlink(file_crpt_file_key);
 195                                 }
 196                                 fclose(fp);
 197                         }
 198                         RSA_free(rsa);
 199                 }
 200         }
 201
 202         /*
 203          * If there is no certificate file on disk, we will be generating a self-signed certificate
 204          * in the next step.  Therefore, if we have neither a CSR nor a certificate, generate
 205          * the CSR in this step so that the next step may commence.
 206          */
 207         if ( (access(file_crpt_file_cer, R_OK) != 0) && (access(file_crpt_file_csr, R_OK) != 0) ) {
 208                 syslog(LOG_INFO, "Generating a generic certificate signing request.");
 209
 210                 /*
 211                  * Read our key from the file.  No, we don't just keep this
 212                  * in memory from the above key-generation function, because
 213                  * there is the possibility that the key was already on disk
 214                  * and we didn't just generate it now.
 215                  */
 216                 fp = fopen(file_crpt_file_key, "r");
 217                 if (fp) {
 218                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 219                         fclose(fp);
 220                 }
 221
 222                 if (rsa) {
 223
 224                         /* Create a public key from the private key */
 225                         if (pk=EVP_PKEY_new(), pk != NULL) {
 226                                 EVP_PKEY_assign_RSA(pk, rsa);
 227                                 if (req = X509_REQ_new(), req != NULL) {
 228
 229                                         /* Set the public key */
 230                                         X509_REQ_set_pubkey(req, pk);
 231                                         X509_REQ_set_version(req, 0L);
 232
 233                                         name = X509_REQ_get_subject_name(req);
 234
 235                                         /* Tell it who we are */
 236                                         X509_NAME_add_entry_by_txt(name, "C", MBSTRING_ASC, (unsigned const char *)"ZZ", -1, -1, 0);
 237                                         X509_NAME_add_entry_by_txt(name, "ST", MBSTRING_ASC, (unsigned const char *)"The World", -1, -1, 0);
 238                                         X509_NAME_add_entry_by_txt(name, "L", MBSTRING_ASC, (unsigned const char *)"My Location", -1, -1, 0);
 239                                         X509_NAME_add_entry_by_txt(name, "O", MBSTRING_ASC, (unsigned const char *)"Generic certificate", -1, -1, 0);
 240                                         X509_NAME_add_entry_by_txt(name, "OU", MBSTRING_ASC, (unsigned const char *)"Citadel server", -1, -1, 0);
 241                                         X509_NAME_add_entry_by_txt(name, "CN", MBSTRING_ASC, (unsigned const char *)"*", -1, -1, 0);
 242                                         X509_REQ_set_subject_name(req, name);
 243
 244                                         /* Sign the CSR */
 245                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 246                                                 syslog(LOG_CRIT, "X509_REQ_sign(): error");
 247                                         }
 248                                         else {
 249                                                 /* Write it to disk. */
 250                                                 fp = fopen(file_crpt_file_csr, "w");
 251                                                 if (fp != NULL) {
 252                                                         chmod(file_crpt_file_csr, 0600);
 253                                                         PEM_write_X509_REQ(fp, req);
 254                                                         fclose(fp);
 255                                                 }
 256                                         }
 257
 258                                         X509_REQ_free(req);
 259                                 }
 260                         }
 261
 262                         RSA_free(rsa);
 263                 }
 264
 265                 else {
 266                         syslog(LOG_CRIT, "Unable to read private key.");
 267                 }
 268         }
 269
 270
 271
 272         /*
 273          * Generate a self-signed certificate if we don't have one.
 274          */
 275         if (access(file_crpt_file_cer, R_OK) != 0) {
 276                 syslog(LOG_INFO, "Generating a generic self-signed certificate.");
 277
 278                 /* Same deal as before: always read the key from disk because
 279                  * it may or may not have just been generated.
 280                  */
 281                 fp = fopen(file_crpt_file_key, "r");
 282                 if (fp) {
 283                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 284                         fclose(fp);
 285                 }
 286
 287                 /* This also holds true for the CSR. */
 288                 req = NULL;
 289                 cer = NULL;
 290                 pk = NULL;
 291                 if (rsa) {
 292                         if (pk=EVP_PKEY_new(), pk != NULL) {
 293                                 EVP_PKEY_assign_RSA(pk, rsa);
 294                         }
 295
 296                         fp = fopen(file_crpt_file_csr, "r");
 297                         if (fp) {
 298                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 299                                 fclose(fp);
 300                         }
 301
 302                         if (req) {
 303                                 if (cer = X509_new(), cer != NULL) {
 304
 305                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 306                                         X509_set_issuer_name(cer, req->req_info->subject);
 307                                         X509_set_subject_name(cer, req->req_info->subject);
 308                                         X509_gmtime_adj(X509_get_notBefore(cer),0);
 309                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 310                                         req_pkey = X509_REQ_get_pubkey(req);
 311                                         X509_set_pubkey(cer, req_pkey);
 312                                         EVP_PKEY_free(req_pkey);
 313
 314                                         /* Sign the cert */
 315                                         if (!X509_sign(cer, pk, EVP_md5())) {
 316                                                 syslog(LOG_CRIT, "X509_sign(): error");
 317                                         }
 318                                         else {
 319                                                 /* Write it to disk. */
 320                                                 fp = fopen(file_crpt_file_cer, "w");
 321                                                 if (fp != NULL) {
 322                                                         chmod(file_crpt_file_cer, 0600);
 323                                                         PEM_write_X509(fp, cer);
 324                                                         fclose(fp);
 325                                                 }
 326                                         }
 327                                         X509_free(cer);
 328                                 }
 329                         }
 330
 331                         RSA_free(rsa);
 332                 }
 333         }
 334
 335
 336         /*
 337          * Now try to bind to the key and certificate.
 338          */
 339         SSL_CTX_use_certificate_chain_file(ssl_ctx, file_crpt_file_cer);
 340         SSL_CTX_use_PrivateKey_file(ssl_ctx, file_crpt_file_key, SSL_FILETYPE_PEM);
 341         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 342                 syslog(LOG_CRIT, "Cannot install certificate: %s", ERR_reason_error_string(ERR_get_error()));
 343         }
 344
 345         /* Finally let the server know we're here */
 346         CtdlRegisterProtoHook(cmd_stls, "STLS", "Start SSL/TLS session");
 347         CtdlRegisterProtoHook(cmd_gtls, "GTLS",
 348                               "Get SSL/TLS session status");
 349         CtdlRegisterSessionHook(endtls, EVT_STOP, PRIO_STOP + 10);
 350 }
 351
 352
 353 /*
 354  * client_write_ssl() Send binary data to the client encrypted.
 355  */
 356 void client_write_ssl(const char *buf, int nbytes)
 357 {
 358         int retval;
 359         int nremain;
 360         char junk[1];
 361
 362         nremain = nbytes;
 363
 364         while (nremain > 0) {
 365                 if (SSL_want_write(CC->ssl)) {
 366                         if ((SSL_read(CC->ssl, junk, 0)) < 1) {
 367                                 syslog(LOG_DEBUG, "SSL_read in client_write: %s", ERR_reason_error_string(ERR_get_error()));
 368                         }
 369                 }
 370                 retval =
 371                     SSL_write(CC->ssl, &buf[nbytes - nremain], nremain);
 372                 if (retval < 1) {
 373                         long errval;
 374
 375                         errval = SSL_get_error(CC->ssl, retval);
 376                         if (errval == SSL_ERROR_WANT_READ ||
 377                             errval == SSL_ERROR_WANT_WRITE) {
 378                                 sleep(1);
 379                                 continue;
 380                         }
 381                         syslog(LOG_DEBUG, "SSL_write got error %ld, ret %d", errval, retval);
 382                         if (retval == -1)
 383                                 syslog(LOG_DEBUG, "errno is %d", errno);
 384                         endtls();
 385                         client_write(&buf[nbytes - nremain], nremain);
 386                         return;
 387                 }
 388                 nremain -= retval;
 389         }
 390 }
 391
 392
 393 /*
 394  * read data from the encrypted layer.
 395  */
 396 int client_read_sslbuffer(StrBuf *buf, int timeout)
 397 {
 398         char sbuf[16384]; /* OpenSSL communicates in 16k blocks, so let's speak its native tongue. */
 399         int rlen;
 400         char junk[1];
 401         SSL *pssl = CC->ssl;
 402
 403         if (pssl == NULL) return(-1);
 404
 405         while (1) {
 406                 if (SSL_want_read(pssl)) {
 407                         if ((SSL_write(pssl, junk, 0)) < 1) {
 408                                 syslog(LOG_DEBUG, "SSL_write in client_read");
 409                         }
 410                 }
 411                 rlen = SSL_read(pssl, sbuf, sizeof(sbuf));
 412                 if (rlen < 1) {
 413                         long errval;
 414
 415                         errval = SSL_get_error(pssl, rlen);
 416                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 417                                 sleep(1);
 418                                 continue;
 419                         }
 420                         syslog(LOG_DEBUG, "SSL_read got error %ld", errval);
 421                         endtls();
 422                         return (-1);
 423                 }
 424                 StrBufAppendBufPlain(buf, sbuf, rlen, 0);
 425                 return rlen;
 426         }
 427         return (0);
 428 }
 429
 430 int client_readline_sslbuffer(StrBuf *Line, StrBuf *IOBuf, const char **Pos, int timeout)
 431 {
 432         CitContext *CCC = CC;
 433         const char *pos = NULL;
 434         const char *pLF;
 435         int len, rlen;
 436         int nSuccessLess = 0;
 437         const char *pch = NULL;
 438
 439         if ((Line == NULL) ||
 440             (Pos == NULL) ||
 441             (IOBuf == NULL))
 442         {
 443                 if (Pos != NULL)
 444                         *Pos = NULL;
 445 //              *Error = ErrRBLF_PreConditionFailed;
 446                 return -1;
 447         }
 448
 449         pos = *Pos;
 450         if ((StrLength(IOBuf) > 0) &&
 451             (pos != NULL) &&
 452             (pos < ChrPtr(IOBuf) + StrLength(IOBuf)))
 453         {
 454                 pch = pos;
 455                 pch = strchr(pch, '\n');
 456
 457                 if (pch == NULL) {
 458                         StrBufAppendBufPlain(Line, pos,
 459                                              StrLength(IOBuf) - (pos - ChrPtr(IOBuf)), 0);
 460                         FlushStrBuf(IOBuf);
 461                         *Pos = NULL;
 462                 }
 463                 else {
 464                         int n = 0;
 465                         if ((pch > ChrPtr(IOBuf)) &&
 466                             (*(pch - 1) == '\r')) {
 467                                 n = 1;
 468                         }
 469                         StrBufAppendBufPlain(Line, pos,
 470                                              (pch - pos - n), 0);
 471
 472                         if (StrLength(IOBuf) <= (pch - ChrPtr(IOBuf) + 1)) {
 473                                 FlushStrBuf(IOBuf);
 474                                 *Pos = NULL;
 475                         }
 476                         else
 477                                 *Pos = pch + 1;
 478                         return StrLength(Line);
 479                 }
 480         }
 481
 482         pLF = NULL;
 483         while ((nSuccessLess < timeout) &&
 484                (pLF == NULL) &&
 485                (CCC->ssl != NULL)) {
 486
 487                 rlen = client_read_sslbuffer(IOBuf, timeout);
 488                 if (rlen < 1) {
 489 //                      *Error = strerror(errno);
 490 //                      close(*fd);
 491 //                      *fd = -1;
 492                         return -1;
 493                 }
 494                 else if (rlen > 0) {
 495                         pLF = strchr(ChrPtr(IOBuf), '\n');
 496                 }
 497         }
 498         *Pos = NULL;
 499         if (pLF != NULL) {
 500                 pos = ChrPtr(IOBuf);
 501                 len = pLF - pos;
 502                 if (len > 0 && (*(pLF - 1) == '\r') )
 503                         len --;
 504                 StrBufAppendBufPlain(Line, pos, len, 0);
 505                 if (pLF + 1 >= ChrPtr(IOBuf) + StrLength(IOBuf))
 506                 {
 507                         FlushStrBuf(IOBuf);
 508                 }
 509                 else
 510                         *Pos = pLF + 1;
 511                 return StrLength(Line);
 512         }
 513 //      *Error = ErrRBLF_NotEnoughSentFromServer;
 514         return -1;
 515 }
 516
 517
 518
 519 int client_read_sslblob(StrBuf *Target, long bytes, int timeout)
 520 {
 521         long baselen;
 522         long RemainRead;
 523         int retval = 0;
 524         CitContext *CCC = CC;
 525
 526         baselen = StrLength(Target);
 527
 528         if (StrLength(CCC->RecvBuf.Buf) > 0)
 529         {
 530                 long RemainLen;
 531                 long TotalLen;
 532                 const char *pchs;
 533
 534                 if (CCC->RecvBuf.ReadWritePointer == NULL)
 535                         CCC->RecvBuf.ReadWritePointer = ChrPtr(CCC->RecvBuf.Buf);
 536                 pchs = ChrPtr(CCC->RecvBuf.Buf);
 537                 TotalLen = StrLength(CCC->RecvBuf.Buf);
 538                 RemainLen = TotalLen - (pchs - CCC->RecvBuf.ReadWritePointer);
 539                 if (RemainLen > bytes)
 540                         RemainLen = bytes;
 541                 if (RemainLen > 0)
 542                 {
 543                         StrBufAppendBufPlain(Target,
 544                                              CCC->RecvBuf.ReadWritePointer,
 545                                              RemainLen, 0);
 546                         CCC->RecvBuf.ReadWritePointer += RemainLen;
 547                 }
 548                 if ((ChrPtr(CCC->RecvBuf.Buf) + StrLength(CCC->RecvBuf.Buf)) <= CCC->RecvBuf.ReadWritePointer)
 549                 {
 550                         CCC->RecvBuf.ReadWritePointer = NULL;
 551                         FlushStrBuf(CCC->RecvBuf.Buf);
 552                 }
 553         }
 554
 555         if (StrLength(Target) >= bytes + baselen)
 556                 return 1;
 557
 558         CCC->RecvBuf.ReadWritePointer = NULL;
 559
 560         while ((StrLength(Target) < bytes + baselen) &&
 561                (retval >= 0))
 562         {
 563                 retval = client_read_sslbuffer(CCC->RecvBuf.Buf, timeout);
 564                 if (retval >= 0) {
 565                         RemainRead = bytes - (StrLength (Target) - baselen);
 566                         if (RemainRead < StrLength(CCC->RecvBuf.Buf))
 567                         {
 568                                 StrBufAppendBufPlain(
 569                                         Target,
 570                                         ChrPtr(CCC->RecvBuf.Buf),
 571                                         RemainRead, 0);
 572                                 CCC->RecvBuf.ReadWritePointer = ChrPtr(CCC->RecvBuf.Buf) + RemainRead;
 573                                 break;
 574                         }
 575                         StrBufAppendBuf(Target, CCC->RecvBuf.Buf, 0); /* todo: Buf > bytes? */
 576                         FlushStrBuf(CCC->RecvBuf.Buf);
 577                 }
 578                 else
 579                 {
 580                         FlushStrBuf(CCC->RecvBuf.Buf);
 581                         return -1;
 582
 583                 }
 584         }
 585         return 1;
 586 }
 587
 588
 589 /*
 590  * CtdlStartTLS() starts SSL/TLS encryption for the current session.  It
 591  * must be supplied with pre-generated strings for responses of "ok," "no
 592  * support for TLS," and "error" so that we can use this in any protocol.
 593  */
 594 void CtdlStartTLS(char *ok_response, char *nosup_response,
 595                         char *error_response) {
 596
 597         int retval, bits, alg_bits;
 598
 599         if (!ssl_ctx) {
 600                 syslog(LOG_CRIT, "SSL failed: no ssl_ctx exists?");
 601                 if (nosup_response != NULL) cprintf("%s", nosup_response);
 602                 return;
 603         }
 604         if (!(CC->ssl = SSL_new(ssl_ctx))) {
 605                 syslog(LOG_CRIT, "SSL_new failed: %s",
 606                                 ERR_reason_error_string(ERR_get_error()));
 607                 if (error_response != NULL) cprintf("%s", error_response);
 608                 return;
 609         }
 610         if (!(SSL_set_fd(CC->ssl, CC->client_socket))) {
 611                 syslog(LOG_CRIT, "SSL_set_fd failed: %s", ERR_reason_error_string(ERR_get_error()));
 612                 SSL_free(CC->ssl);
 613                 CC->ssl = NULL;
 614                 if (error_response != NULL) cprintf("%s", error_response);
 615                 return;
 616         }
 617         if (ok_response != NULL) cprintf("%s", ok_response);
 618         retval = SSL_accept(CC->ssl);
 619         if (retval < 1) {
 620                 /*
 621                  * Can't notify the client of an error here; they will
 622                  * discover the problem at the SSL layer and should
 623                  * revert to unencrypted communications.
 624                  */
 625                 long errval;
 626                 char error_string[128];
 627
 628                 errval = SSL_get_error(CC->ssl, retval);
 629                 syslog(LOG_CRIT, "SSL_accept failed: retval=%d, errval=%ld, err=%s",
 630                         retval,
 631                         errval,
 632                         ERR_error_string(errval, error_string)
 633                 );
 634                 SSL_free(CC->ssl);
 635                 CC->ssl = NULL;
 636                 return;
 637         }
 638         BIO_set_close(CC->ssl->rbio, BIO_NOCLOSE);
 639         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl), &alg_bits);
 640         syslog(LOG_INFO, "SSL/TLS using %s on %s (%d of %d bits)",
 641                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 642                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 643                 bits, alg_bits);
 644         CC->redirect_ssl = 1;
 645 }
 646
 647
 648 /*
 649  * cmd_stls() starts SSL/TLS encryption for the current session
 650  */
 651 void cmd_stls(char *params)
 652 {
 653         char ok_response[SIZ];
 654         char nosup_response[SIZ];
 655         char error_response[SIZ];
 656
 657         unbuffer_output();
 658
 659         sprintf(ok_response,
 660                 "%d Begin TLS negotiation now\n",
 661                 CIT_OK);
 662         sprintf(nosup_response,
 663                 "%d TLS not supported here\n",
 664                 ERROR + CMD_NOT_SUPPORTED);
 665         sprintf(error_response,
 666                 "%d TLS negotiation error\n",
 667                 ERROR + INTERNAL_ERROR);
 668
 669         CtdlStartTLS(ok_response, nosup_response, error_response);
 670 }
 671
 672
 673 /*
 674  * cmd_gtls() returns status info about the TLS connection
 675  */
 676 void cmd_gtls(char *params)
 677 {
 678         int bits, alg_bits;
 679
 680         if (!CC->ssl || !CC->redirect_ssl) {
 681                 cprintf("%d Session is not encrypted.\n", ERROR);
 682                 return;
 683         }
 684         bits =
 685             SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl),
 686                                 &alg_bits);
 687         cprintf("%d %s|%s|%d|%d\n", CIT_OK,
 688                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 689                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 690                 alg_bits, bits);
 691 }
 692
 693
 694 /*
 695  * endtls() shuts down the TLS connection
 696  *
 697  * WARNING:  This may make your session vulnerable to a known plaintext
 698  * attack in the current implmentation.
 699  */
 700 void endtls(void)
 701 {
 702         if (!CC->ssl) {
 703                 CC->redirect_ssl = 0;
 704                 return;
 705         }
 706
 707         syslog(LOG_INFO, "Ending SSL/TLS");
 708         SSL_shutdown(CC->ssl);
 709         SSL_free(CC->ssl);
 710         CC->ssl = NULL;
 711         CC->redirect_ssl = 0;
 712 }
 713
 714
 715 /*
 716  * ssl_lock() callback for OpenSSL mutex locks
 717  */
 718 void ssl_lock(int mode, int n, const char *file, int line)
 719 {
 720         if (mode & CRYPTO_LOCK)
 721                 pthread_mutex_lock(SSLCritters[n]);
 722         else
 723                 pthread_mutex_unlock(SSLCritters[n]);
 724 }
 725 #endif                          /* HAVE_OPENSSL */