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,
 264                                                                    (unsigned char*) config.c_humannode,
 265                                                                    -1, -1, 0);
 266
 267                                         X509_NAME_add_entry_by_txt(name, "OU",
 268                                                                    MBSTRING_ASC,
 269                                                                    (unsigned const char*)"Citadel server",
 270                                                                    -1, -1, 0);
 271
 272                                         /* X509_NAME_add_entry_by_txt(name, "CN",
 273                                                 MBSTRING_ASC, config.c_fqdn, -1, -1, 0);
 274                                         */
 275
 276                                         X509_NAME_add_entry_by_txt(name,
 277                                                                    "CN",
 278                                                                    MBSTRING_ASC,
 279                                                                    (const unsigned char *)"*", -1, -1, 0);
 280
 281                                         X509_REQ_set_subject_name(req, name);
 282
 283                                         /* Sign the CSR */
 284                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 285                                                 CtdlLogPrintf(CTDL_CRIT, "X509_REQ_sign(): error\n");
 286                                         }
 287                                         else {
 288                                                 /* Write it to disk. */
 289                                                 fp = fopen(file_crpt_file_csr, "w");
 290                                                 if (fp != NULL) {
 291                                                         chmod(file_crpt_file_csr, 0600);
 292                                                         PEM_write_X509_REQ(fp, req);
 293                                                         fclose(fp);
 294                                                 }
 295                                         }
 296
 297                                         X509_REQ_free(req);
 298                                 }
 299                         }
 300
 301                         RSA_free(rsa);
 302                 }
 303
 304                 else {
 305                         CtdlLogPrintf(CTDL_CRIT, "Unable to read private key.\n");
 306                 }
 307         }
 308
 309
 310
 311         /*
 312          * Generate a self-signed certificate if we don't have one.
 313          */
 314         if (access(file_crpt_file_cer, R_OK) != 0) {
 315                 CtdlLogPrintf(CTDL_INFO, "Generating a self-signed certificate.\n");
 316
 317                 /* Same deal as before: always read the key from disk because
 318                  * it may or may not have just been generated.
 319                  */
 320                 fp = fopen(file_crpt_file_key, "r");
 321                 if (fp) {
 322                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 323                         fclose(fp);
 324                 }
 325
 326                 /* This also holds true for the CSR. */
 327                 req = NULL;
 328                 cer = NULL;
 329                 pk = NULL;
 330                 if (rsa) {
 331                         if (pk=EVP_PKEY_new(), pk != NULL) {
 332                                 EVP_PKEY_assign_RSA(pk, rsa);
 333                         }
 334
 335                         fp = fopen(file_crpt_file_csr, "r");
 336                         if (fp) {
 337                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 338                                 fclose(fp);
 339                         }
 340
 341                         if (req) {
 342                                 if (cer = X509_new(), cer != NULL) {
 343
 344                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 345                                         X509_set_issuer_name(cer, req->req_info->subject);
 346                                         X509_set_subject_name(cer, req->req_info->subject);
 347                                         X509_gmtime_adj(X509_get_notBefore(cer),0);
 348                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 349                                         req_pkey = X509_REQ_get_pubkey(req);
 350                                         X509_set_pubkey(cer, req_pkey);
 351                                         EVP_PKEY_free(req_pkey);
 352
 353                                         /* Sign the cert */
 354                                         if (!X509_sign(cer, pk, EVP_md5())) {
 355                                                 CtdlLogPrintf(CTDL_CRIT, "X509_sign(): error\n");
 356                                         }
 357                                         else {
 358                                                 /* Write it to disk. */
 359                                                 fp = fopen(file_crpt_file_cer, "w");
 360                                                 if (fp != NULL) {
 361                                                         chmod(file_crpt_file_cer, 0600);
 362                                                         PEM_write_X509(fp, cer);
 363                                                         fclose(fp);
 364                                                 }
 365                                         }
 366                                         X509_free(cer);
 367                                 }
 368                         }
 369
 370                         RSA_free(rsa);
 371                 }
 372         }
 373
 374
 375         /*
 376          * Now try to bind to the key and certificate.
 377          */
 378         SSL_CTX_use_certificate_chain_file(ssl_ctx, file_crpt_file_cer);
 379         SSL_CTX_use_PrivateKey_file(ssl_ctx, file_crpt_file_key, SSL_FILETYPE_PEM);
 380         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 381                 CtdlLogPrintf(CTDL_CRIT, "Cannot install certificate: %s\n",
 382                                 ERR_reason_error_string(ERR_get_error()));
 383         }
 384
 385         /* Finally let the server know we're here */
 386         CtdlRegisterProtoHook(cmd_stls, "STLS", "Start SSL/TLS session");
 387         CtdlRegisterProtoHook(cmd_gtls, "GTLS",
 388                               "Get SSL/TLS session status");
 389         CtdlRegisterSessionHook(endtls, EVT_STOP);
 390 }
 391
 392
 393 /*
 394  * client_write_ssl() Send binary data to the client encrypted.
 395  */
 396 void client_write_ssl(const char *buf, int nbytes)
 397 {
 398         int retval;
 399         int nremain;
 400         char junk[1];
 401
 402         nremain = nbytes;
 403
 404         while (nremain > 0) {
 405                 if (SSL_want_write(CC->ssl)) {
 406                         if ((SSL_read(CC->ssl, junk, 0)) < 1) {
 407                                 CtdlLogPrintf(CTDL_DEBUG, "SSL_read in client_write: %s\n", ERR_reason_error_string(ERR_get_error()));
 408                         }
 409                 }
 410                 retval =
 411                     SSL_write(CC->ssl, &buf[nbytes - nremain], nremain);
 412                 if (retval < 1) {
 413                         long errval;
 414
 415                         errval = SSL_get_error(CC->ssl, retval);
 416                         if (errval == SSL_ERROR_WANT_READ ||
 417                             errval == SSL_ERROR_WANT_WRITE) {
 418                                 sleep(1);
 419                                 continue;
 420                         }
 421                         CtdlLogPrintf(CTDL_DEBUG, "SSL_write got error %ld, ret %d\n", errval, retval);
 422                         if (retval == -1)
 423                                 CtdlLogPrintf(CTDL_DEBUG, "errno is %d\n", errno);
 424                         endtls();
 425                         client_write(&buf[nbytes - nremain], nremain);
 426                         return;
 427                 }
 428                 nremain -= retval;
 429         }
 430 }
 431
 432
 433 /*
 434  * read data from the encrypted layer.
 435  */
 436 int client_read_sslbuffer(StrBuf *buf, int timeout)
 437 {
 438         char sbuf[16384]; /* OpenSSL communicates in 16k blocks, so let's speak its native tongue. */
 439         int rlen;
 440         char junk[1];
 441         SSL *pssl = CC->ssl;
 442
 443         if (pssl == NULL) return(-1);
 444
 445         while (1) {
 446                 if (SSL_want_read(pssl)) {
 447                         if ((SSL_write(pssl, junk, 0)) < 1) {
 448                                 CtdlLogPrintf(CTDL_DEBUG, "SSL_write in client_read\n");
 449                         }
 450                 }
 451                 rlen = SSL_read(pssl, sbuf, sizeof(sbuf));
 452                 if (rlen < 1) {
 453                         long errval;
 454
 455                         errval = SSL_get_error(pssl, rlen);
 456                         if (errval == SSL_ERROR_WANT_READ || 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 (-1);
 463                 }
 464                 StrBufAppendBufPlain(buf, sbuf, rlen, 0);
 465                 return rlen;
 466         }
 467         return (0);
 468 }
 469
 470 int client_readline_sslbuffer(StrBuf *Line, StrBuf *IOBuf, const char **Pos, int timeout)
 471 {
 472         CitContext *CCC = CC;
 473         const char *pos = NULL;
 474         const char *pLF;
 475         int len, rlen, retlen;
 476         int nSuccessLess = 0;
 477         const char *pch = NULL;
 478
 479         retlen = 0;
 480         if ((Line == NULL) ||
 481             (Pos == NULL) ||
 482             (IOBuf == NULL))
 483         {
 484                 if (Pos != NULL)
 485                         *Pos = NULL;
 486 //              *Error = ErrRBLF_PreConditionFailed;
 487                 return -1;
 488         }
 489
 490         pos = *Pos;
 491         if ((StrLength(IOBuf) > 0) &&
 492             (pos != NULL) &&
 493             (pos < ChrPtr(IOBuf) + StrLength(IOBuf)))
 494         {
 495                 pch = pos;
 496                 pch = strchr(pch, '\n');
 497
 498                 if (pch == NULL) {
 499                         StrBufAppendBufPlain(Line, pos,
 500                                              StrLength(IOBuf) - (pos - ChrPtr(IOBuf)), 0);
 501                         FlushStrBuf(IOBuf);
 502                         pos = *Pos = NULL;
 503                 }
 504                 else {
 505                         int n = 0;
 506                         if ((pch > ChrPtr(IOBuf)) &&
 507                             (*(pch - 1) == '\r')) {
 508                                 n = 1;
 509                         }
 510                         StrBufAppendBufPlain(Line, pos,
 511                                              (pch - pos - n), 0);
 512
 513                         if (StrLength(IOBuf) <= (pch - ChrPtr(IOBuf) + 1)) {
 514                                 FlushStrBuf(IOBuf);
 515                                 pos = *Pos = NULL;
 516                         }
 517                         else
 518                                 *Pos = pch + 1;
 519                         return StrLength(Line);
 520                 }
 521         }
 522
 523         pLF = NULL;
 524         while ((nSuccessLess < timeout) &&
 525                (pLF == NULL) &&
 526                (CCC->ssl != NULL)) {
 527
 528                 rlen = client_read_sslbuffer(IOBuf, timeout);
 529                 if (rlen < 1) {
 530 //                      *Error = strerror(errno);
 531 //                      close(*fd);
 532 //                      *fd = -1;
 533                         return -1;
 534                 }
 535                 else if (rlen > 0) {
 536                         pLF = strchr(ChrPtr(IOBuf), '\n');
 537                 }
 538         }
 539         *Pos = NULL;
 540         if (pLF != NULL) {
 541                 pos = ChrPtr(IOBuf);
 542                 len = pLF - pos;
 543                 if (len > 0 && (*(pLF - 1) == '\r') )
 544                         len --;
 545                 StrBufAppendBufPlain(Line, pos, len, 0);
 546                 if (pLF + 1 >= ChrPtr(IOBuf) + StrLength(IOBuf))
 547                 {
 548                         FlushStrBuf(IOBuf);
 549                 }
 550                 else
 551                         *Pos = pLF + 1;
 552                 return StrLength(Line);
 553         }
 554 //      *Error = ErrRBLF_NotEnoughSentFromServer;
 555         return -1;
 556 }
 557
 558
 559
 560 int client_read_sslblob(StrBuf *Target, long bytes, int timeout)
 561 {
 562         long baselen;
 563         long RemainRead;
 564         int retval = 0;
 565         CitContext *CCC = CC;
 566
 567         baselen = StrLength(Target);
 568
 569         if (StrLength(CCC->ReadBuf) > 0)
 570         {
 571                 long RemainLen;
 572                 long TotalLen;
 573                 const char *pchs;
 574
 575                 if (CCC->Pos == NULL)
 576                         CCC->Pos = ChrPtr(CCC->ReadBuf);
 577                 pchs = ChrPtr(CCC->ReadBuf);
 578                 TotalLen = StrLength(CCC->ReadBuf);
 579                 RemainLen = TotalLen - (pchs - CCC->Pos);
 580                 if (RemainLen > bytes)
 581                         RemainLen = bytes;
 582                 if (RemainLen > 0)
 583                 {
 584                         StrBufAppendBufPlain(Target,
 585                                              CCC->Pos,
 586                                              RemainLen, 0);
 587                         CCC->Pos += RemainLen;
 588                 }
 589                 if ((ChrPtr(CCC->ReadBuf) + StrLength(CCC->ReadBuf)) <= CCC->Pos)
 590                 {
 591                         CCC->Pos = NULL;
 592                         FlushStrBuf(CCC->ReadBuf);
 593                 }
 594         }
 595
 596         if (StrLength(Target) >= bytes + baselen)
 597                 return 1;
 598
 599         CCC->Pos = NULL;
 600
 601         while ((StrLength(Target) < bytes + baselen) &&
 602                (retval >= 0))
 603         {
 604                 retval = client_read_sslbuffer(CCC->ReadBuf, timeout);
 605                 if (retval >= 0) {
 606                         RemainRead = bytes - (StrLength (Target) - baselen);
 607                         if (RemainRead > StrLength(CCC->ReadBuf))
 608                         {
 609                                 StrBufAppendBufPlain(
 610                                         Target,
 611                                         ChrPtr(CCC->ReadBuf),
 612                                         RemainRead, 0);
 613                                 CCC->Pos = ChrPtr(CCC->ReadBuf) + RemainRead;
 614                                 break;
 615                         }
 616                         StrBufAppendBuf(Target, CCC->ReadBuf, 0); /* todo: Buf > bytes? */
 617                         FlushStrBuf(CCC->ReadBuf);
 618                 }
 619                 else
 620                 {
 621                         FlushStrBuf(CCC->ReadBuf);
 622                         return -1;
 623
 624                 }
 625         }
 626         return 1;
 627 }
 628
 629
 630 /*
 631  * CtdlStartTLS() starts SSL/TLS encryption for the current session.  It
 632  * must be supplied with pre-generated strings for responses of "ok," "no
 633  * support for TLS," and "error" so that we can use this in any protocol.
 634  */
 635 void CtdlStartTLS(char *ok_response, char *nosup_response,
 636                         char *error_response) {
 637
 638         int retval, bits, alg_bits;
 639
 640         if (!ssl_ctx) {
 641                 CtdlLogPrintf(CTDL_CRIT, "SSL failed: no ssl_ctx exists?\n");
 642                 if (nosup_response != NULL) cprintf("%s", nosup_response);
 643                 return;
 644         }
 645         if (!(CC->ssl = SSL_new(ssl_ctx))) {
 646                 CtdlLogPrintf(CTDL_CRIT, "SSL_new failed: %s\n",
 647                                 ERR_reason_error_string(ERR_get_error()));
 648                 if (error_response != NULL) cprintf("%s", error_response);
 649                 return;
 650         }
 651         if (!(SSL_set_fd(CC->ssl, CC->client_socket))) {
 652                 CtdlLogPrintf(CTDL_CRIT, "SSL_set_fd failed: %s\n",
 653                         ERR_reason_error_string(ERR_get_error()));
 654                 SSL_free(CC->ssl);
 655                 CC->ssl = NULL;
 656                 if (error_response != NULL) cprintf("%s", error_response);
 657                 return;
 658         }
 659         if (ok_response != NULL) cprintf("%s", ok_response);
 660         retval = SSL_accept(CC->ssl);
 661         if (retval < 1) {
 662                 /*
 663                  * Can't notify the client of an error here; they will
 664                  * discover the problem at the SSL layer and should
 665                  * revert to unencrypted communications.
 666                  */
 667                 long errval;
 668                 char error_string[128];
 669
 670                 errval = SSL_get_error(CC->ssl, retval);
 671                 CtdlLogPrintf(CTDL_CRIT, "SSL_accept failed: retval=%d, errval=%ld, err=%s\n",
 672                         retval,
 673                         errval,
 674                         ERR_error_string(errval, error_string)
 675                 );
 676                 SSL_free(CC->ssl);
 677                 CC->ssl = NULL;
 678                 return;
 679         }
 680         BIO_set_close(CC->ssl->rbio, BIO_NOCLOSE);
 681         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl), &alg_bits);
 682         CtdlLogPrintf(CTDL_INFO, "SSL/TLS using %s on %s (%d of %d bits)\n",
 683                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 684                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 685                 bits, alg_bits);
 686         CC->redirect_ssl = 1;
 687 }
 688
 689
 690 /*
 691  * cmd_stls() starts SSL/TLS encryption for the current session
 692  */
 693 void cmd_stls(char *params)
 694 {
 695         char ok_response[SIZ];
 696         char nosup_response[SIZ];
 697         char error_response[SIZ];
 698
 699         unbuffer_output();
 700
 701         sprintf(ok_response,
 702                 "%d Begin TLS negotiation now\n",
 703                 CIT_OK);
 704         sprintf(nosup_response,
 705                 "%d TLS not supported here\n",
 706                 ERROR + CMD_NOT_SUPPORTED);
 707         sprintf(error_response,
 708                 "%d TLS negotiation error\n",
 709                 ERROR + INTERNAL_ERROR);
 710
 711         CtdlStartTLS(ok_response, nosup_response, error_response);
 712 }
 713
 714
 715 /*
 716  * cmd_gtls() returns status info about the TLS connection
 717  */
 718 void cmd_gtls(char *params)
 719 {
 720         int bits, alg_bits;
 721
 722         if (!CC->ssl || !CC->redirect_ssl) {
 723                 cprintf("%d Session is not encrypted.\n", ERROR);
 724                 return;
 725         }
 726         bits =
 727             SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl),
 728                                 &alg_bits);
 729         cprintf("%d %s|%s|%d|%d\n", CIT_OK,
 730                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 731                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 732                 alg_bits, bits);
 733 }
 734
 735
 736 /*
 737  * endtls() shuts down the TLS connection
 738  *
 739  * WARNING:  This may make your session vulnerable to a known plaintext
 740  * attack in the current implmentation.
 741  */
 742 void endtls(void)
 743 {
 744         if (!CC->ssl) {
 745                 CC->redirect_ssl = 0;
 746                 return;
 747         }
 748
 749         CtdlLogPrintf(CTDL_INFO, "Ending SSL/TLS\n");
 750         SSL_shutdown(CC->ssl);
 751         SSL_free(CC->ssl);
 752         CC->ssl = NULL;
 753         CC->redirect_ssl = 0;
 754 }
 755
 756
 757 /*
 758  * ssl_lock() callback for OpenSSL mutex locks
 759  */
 760 void ssl_lock(int mode, int n, const char *file, int line)
 761 {
 762         if (mode & CRYPTO_LOCK)
 763                 pthread_mutex_lock(SSLCritters[n]);
 764         else
 765                 pthread_mutex_unlock(SSLCritters[n]);
 766 }
 767 #endif                          /* HAVE_OPENSSL */