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