webcit/crypto.c

   1 /*
   2  * $Id$
   3  *
   4  * Copyright (c) 1996-2010 by the citadel.org team
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include "sysdep.h"
  22 #ifdef HAVE_OPENSSL
  23
  24 #include "webcit.h"
  25 #include "webserver.h"
  26
  27 /* where to find the keys */
  28 #define CTDL_CRYPTO_DIR         ctdl_key_dir
  29 #define CTDL_KEY_PATH           file_crpt_file_key
  30 #define CTDL_CSR_PATH           file_crpt_file_csr
  31 #define CTDL_CER_PATH           file_crpt_file_cer
  32 #define SIGN_DAYS               3650                    /* how long our certificate should live */
  33
  34 SSL_CTX *ssl_ctx;               /* SSL context */
  35 pthread_mutex_t **SSLCritters;  /* Things needing locking */
  36 char *ssl_cipher_list = DEFAULT_SSL_CIPHER_LIST;
  37
  38 pthread_key_t ThreadSSL;        /* Per-thread SSL context */
  39
  40 static unsigned long id_callback(void)
  41 {
  42         return (unsigned long) pthread_self();
  43 }
  44
  45 void shutdown_ssl(void)
  46 {
  47         ERR_free_strings();
  48
  49         /* Openssl requires these while shutdown.
  50          * Didn't find a way to get out of this clean.
  51          * int i, n = CRYPTO_num_locks();
  52          * for (i = 0; i < n; i++)
  53          *      free(SSLCritters[i]);
  54          * free(SSLCritters);
  55          */
  56 }
  57
  58 /*
  59  * initialize ssl engine, load certs and initialize openssl internals
  60  */
  61 void init_ssl(void)
  62 {
  63         SSL_METHOD *ssl_method;
  64         RSA *rsa=NULL;
  65         X509_REQ *req = NULL;
  66         X509 *cer = NULL;
  67         EVP_PKEY *pk = NULL;
  68         EVP_PKEY *req_pkey = NULL;
  69         X509_NAME *name = NULL;
  70         FILE *fp;
  71         char buf[SIZ];
  72         int rv = 0;
  73
  74         if (!access("/var/run/egd-pool", F_OK)) {
  75                 RAND_egd("/var/run/egd-pool");
  76         }
  77
  78         if (!RAND_status()) {
  79                 lprintf(3, "PRNG not adequately seeded, won't do SSL/TLS\n");
  80                 return;
  81         }
  82         SSLCritters = malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
  83         if (!SSLCritters) {
  84                 lprintf(1, "citserver: can't allocate memory!!\n");
  85                 /* Nothing's been initialized, just die */
  86                 ShutDownWebcit();
  87                 exit(WC_EXIT_SSL);
  88         } else {
  89                 int a;
  90
  91                 for (a = 0; a < CRYPTO_num_locks(); a++) {
  92                         SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
  93                         if (!SSLCritters[a]) {
  94                                 lprintf(1,
  95                                         "citserver: can't allocate memory!!\n");
  96                                 /** Nothing's been initialized, just die */
  97                                 ShutDownWebcit();
  98                                 exit(WC_EXIT_SSL);
  99                         }
 100                         pthread_mutex_init(SSLCritters[a], NULL);
 101                 }
 102         }
 103
 104         /*
 105          * Initialize SSL transport layer
 106          */
 107         SSL_library_init();
 108         SSL_load_error_strings();
 109         ssl_method = SSLv23_server_method();
 110         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
 111                 lprintf(3, "SSL_CTX_new failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 112                 return;
 113         }
 114
 115         lprintf(9, "Requesting cipher list: %s\n", ssl_cipher_list);
 116         if (!(SSL_CTX_set_cipher_list(ssl_ctx, ssl_cipher_list))) {
 117                 lprintf(3, "SSL_CTX_set_cipher_list failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 118                 return;
 119         }
 120
 121         CRYPTO_set_locking_callback(ssl_lock);
 122         CRYPTO_set_id_callback(id_callback);
 123
 124         /*
 125          * Get our certificates in order. (FIXME: dirify. this is a setup job.)
 126          * First, create the key/cert directory if it's not there already...
 127          */
 128         mkdir(CTDL_CRYPTO_DIR, 0700);
 129
 130         /*
 131          * Before attempting to generate keys/certificates, first try
 132          * link to them from the Citadel server if it's on the same host.
 133          * We ignore any error return because it either meant that there
 134          * was nothing in Citadel to link from (in which case we just
 135          * generate new files) or the target files already exist (which
 136          * is not fatal either).
 137          */
 138         if (!strcasecmp(ctdlhost, "uds")) {
 139                 sprintf(buf, "%s/keys/citadel.key", ctdlport);
 140                 rv = symlink(buf, CTDL_KEY_PATH);
 141                 if (!rv) lprintf(1, "%s\n", strerror(errno));
 142                 sprintf(buf, "%s/keys/citadel.csr", ctdlport);
 143                 rv = symlink(buf, CTDL_CSR_PATH);
 144                 if (!rv) lprintf(1, "%s\n", strerror(errno));
 145                 sprintf(buf, "%s/keys/citadel.cer", ctdlport);
 146                 rv = symlink(buf, CTDL_CER_PATH);
 147                 if (!rv) lprintf(1, "%s\n", strerror(errno));
 148         }
 149
 150         /*
 151          * If we still don't have a private key, generate one.
 152          */
 153         if (access(CTDL_KEY_PATH, R_OK) != 0) {
 154                 lprintf(5, "Generating RSA key pair.\n");
 155                 rsa = RSA_generate_key(1024,    /* modulus size */
 156                                         65537,  /* exponent */
 157                                         NULL,   /* no callback */
 158                                         NULL    /* no callback */
 159                 );
 160                 if (rsa == NULL) {
 161                         lprintf(3, "Key generation failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 162                 }
 163                 if (rsa != NULL) {
 164                         fp = fopen(CTDL_KEY_PATH, "w");
 165                         if (fp != NULL) {
 166                                 chmod(CTDL_KEY_PATH, 0600);
 167                                 if (PEM_write_RSAPrivateKey(fp, /* the file */
 168                                                         rsa,    /* the key */
 169                                                         NULL,   /* no enc */
 170                                                         NULL,   /* no passphr */
 171                                                         0,      /* no passphr */
 172                                                         NULL,   /* no callbk */
 173                                                         NULL    /* no callbk */
 174                                 ) != 1) {
 175                                         lprintf(3, "Cannot write key: %s\n",
 176                                                 ERR_reason_error_string(ERR_get_error()));
 177                                         unlink(CTDL_KEY_PATH);
 178                                 }
 179                                 fclose(fp);
 180                         }
 181                         else {
 182                                 lprintf(3, "Cannot write key: %s\n", CTDL_KEY_PATH);
 183                                 ShutDownWebcit();
 184                                 exit(0);
 185                         }
 186                         RSA_free(rsa);
 187                 }
 188         }
 189
 190         /*
 191          * If there is no certificate file on disk, we will be generating a self-signed certificate
 192          * in the next step.  Therefore, if we have neither a CSR nor a certificate, generate
 193          * the CSR in this step so that the next step may commence.
 194          */
 195         if ( (access(CTDL_CER_PATH, R_OK) != 0) && (access(CTDL_CSR_PATH, R_OK) != 0) ) {
 196                 lprintf(5, "Generating a certificate signing request.\n");
 197
 198                 /*
 199                  * Read our key from the file.  No, we don't just keep this
 200                  * in memory from the above key-generation function, because
 201                  * there is the possibility that the key was already on disk
 202                  * and we didn't just generate it now.
 203                  */
 204                 fp = fopen(CTDL_KEY_PATH, "r");
 205                 if (fp) {
 206                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 207                         fclose(fp);
 208                 }
 209
 210                 if (rsa) {
 211
 212                         /** Create a public key from the private key */
 213                         if (pk=EVP_PKEY_new(), pk != NULL) {
 214                                 EVP_PKEY_assign_RSA(pk, rsa);
 215                                 if (req = X509_REQ_new(), req != NULL) {
 216                                         const char *env;
 217                                         /* Set the public key */
 218                                         X509_REQ_set_pubkey(req, pk);
 219                                         X509_REQ_set_version(req, 0L);
 220
 221                                         name = X509_REQ_get_subject_name(req);
 222
 223                                         /* Tell it who we are */
 224
 225                                         /*
 226                                          * We used to add these fields to the subject, but
 227                                          * now we don't.  Someone doing this for real isn't
 228                                          * going to use the webcit-generated CSR anyway.
 229                                          *
 230                                         X509_NAME_add_entry_by_txt(name, "C",
 231                                                 MBSTRING_ASC, "US", -1, -1, 0);
 232                                         *
 233                                         X509_NAME_add_entry_by_txt(name, "ST",
 234                                                 MBSTRING_ASC, "New York", -1, -1, 0);
 235                                         *
 236                                         X509_NAME_add_entry_by_txt(name, "L",
 237                                                 MBSTRING_ASC, "Mount Kisco", -1, -1, 0);
 238                                         */
 239
 240                                         env = getenv("O");
 241                                         if (env == NULL)
 242                                                 env = "Organization name",
 243
 244                                         X509_NAME_add_entry_by_txt(
 245                                                 name, "O",
 246                                                 MBSTRING_ASC,
 247                                                 (unsigned char*)env,
 248                                                 -1, -1, 0
 249                                         );
 250
 251                                         env = getenv("OU");
 252                                         if (env == NULL)
 253                                                 env = "Citadel server";
 254
 255                                         X509_NAME_add_entry_by_txt(
 256                                                 name, "OU",
 257                                                 MBSTRING_ASC,
 258                                                 (unsigned char*)env,
 259                                                 -1, -1, 0
 260                                         );
 261
 262                                         env = getenv("CN");
 263                                         if (env == NULL)
 264                                                 env = "*";
 265
 266                                         X509_NAME_add_entry_by_txt(
 267                                                 name, "CN",
 268                                                 MBSTRING_ASC,
 269                                                 (unsigned char*)env,
 270                                                 -1, -1, 0
 271                                         );
 272
 273                                         X509_REQ_set_subject_name(req, name);
 274
 275                                         /* Sign the CSR */
 276                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 277                                                 lprintf(3, "X509_REQ_sign(): error\n");
 278                                         }
 279                                         else {
 280                                                 /* Write it to disk. */
 281                                                 fp = fopen(CTDL_CSR_PATH, "w");
 282                                                 if (fp != NULL) {
 283                                                         chmod(CTDL_CSR_PATH, 0600);
 284                                                         PEM_write_X509_REQ(fp, req);
 285                                                         fclose(fp);
 286                                                 }
 287                                                 else {
 288                                                         lprintf(3, "Cannot write key: %s\n", CTDL_CSR_PATH);
 289                                                         ShutDownWebcit();
 290                                                         exit(0);
 291                                                 }
 292                                         }
 293
 294                                         X509_REQ_free(req);
 295                                 }
 296                         }
 297
 298                         RSA_free(rsa);
 299                 }
 300
 301                 else {
 302                         lprintf(3, "Unable to read private key.\n");
 303                 }
 304         }
 305
 306
 307
 308         /*
 309          * Generate a self-signed certificate if we don't have one.
 310          */
 311         if (access(CTDL_CER_PATH, R_OK) != 0) {
 312                 lprintf(5, "Generating a self-signed certificate.\n");
 313
 314                 /* Same deal as before: always read the key from disk because
 315                  * it may or may not have just been generated.
 316                  */
 317                 fp = fopen(CTDL_KEY_PATH, "r");
 318                 if (fp) {
 319                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 320                         fclose(fp);
 321                 }
 322
 323                 /* This also holds true for the CSR. */
 324                 req = NULL;
 325                 cer = NULL;
 326                 pk = NULL;
 327                 if (rsa) {
 328                         if (pk=EVP_PKEY_new(), pk != NULL) {
 329                                 EVP_PKEY_assign_RSA(pk, rsa);
 330                         }
 331
 332                         fp = fopen(CTDL_CSR_PATH, "r");
 333                         if (fp) {
 334                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 335                                 fclose(fp);
 336                         }
 337
 338                         if (req) {
 339                                 if (cer = X509_new(), cer != NULL) {
 340
 341                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 342                                         X509_set_issuer_name(cer, req->req_info->subject);
 343                                         X509_set_subject_name(cer, req->req_info->subject);
 344                                         X509_gmtime_adj(X509_get_notBefore(cer), 0);
 345                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 346
 347                                         req_pkey = X509_REQ_get_pubkey(req);
 348                                         X509_set_pubkey(cer, req_pkey);
 349                                         EVP_PKEY_free(req_pkey);
 350
 351                                         /* Sign the cert */
 352                                         if (!X509_sign(cer, pk, EVP_md5())) {
 353                                                 lprintf(3, "X509_sign(): error\n");
 354                                         }
 355                                         else {
 356                                                 /* Write it to disk. */
 357                                                 fp = fopen(CTDL_CER_PATH, "w");
 358                                                 if (fp != NULL) {
 359                                                         chmod(CTDL_CER_PATH, 0600);
 360                                                         PEM_write_X509(fp, cer);
 361                                                         fclose(fp);
 362                                                 }
 363                                                 else {
 364                                                         lprintf(3, "Cannot write key: %s\n", CTDL_CER_PATH);
 365                                                         ShutDownWebcit();
 366                                                         exit(0);
 367                                                 }
 368                                         }
 369                                         X509_free(cer);
 370                                 }
 371                         }
 372
 373                         RSA_free(rsa);
 374                 }
 375         }
 376
 377         /*
 378          * Now try to bind to the key and certificate.
 379          * Note that we use SSL_CTX_use_certificate_chain_file() which allows
 380          * the certificate file to contain intermediate certificates.
 381          */
 382         SSL_CTX_use_certificate_chain_file(ssl_ctx, CTDL_CER_PATH);
 383         SSL_CTX_use_PrivateKey_file(ssl_ctx, CTDL_KEY_PATH, SSL_FILETYPE_PEM);
 384         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 385                 lprintf(3, "Cannot install certificate: %s\n",
 386                                 ERR_reason_error_string(ERR_get_error()));
 387         }
 388
 389 }
 390
 391
 392 /*
 393  * starts SSL/TLS encryption for the current session.
 394  */
 395 int starttls(int sock) {
 396         int retval, bits, alg_bits, r;
 397         SSL *newssl;
 398
 399         pthread_setspecific(ThreadSSL, NULL);
 400
 401         if (!ssl_ctx) {
 402                 return(1);
 403         }
 404         if (!(newssl = SSL_new(ssl_ctx))) {
 405                 lprintf(3, "SSL_new failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 406                 return(2);
 407         }
 408         if (!(SSL_set_fd(newssl, sock))) {
 409                 lprintf(3, "SSL_set_fd failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 410                 SSL_free(newssl);
 411                 return(3);
 412         }
 413         retval = SSL_accept(newssl);
 414         if (retval < 1) {
 415                 /*
 416                  * Can't notify the client of an error here; they will
 417                  * discover the problem at the SSL layer and should
 418                  * revert to unencrypted communications.
 419                  */
 420                 long errval;
 421                 const char *ssl_error_reason = NULL;
 422
 423                 errval = SSL_get_error(newssl, retval);
 424                 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 425                 if (ssl_error_reason == NULL) {
 426                         lprintf(3, "SSL_accept failed: errval=%i, retval=%i %s\n", errval, retval, strerror(errval));
 427                 }
 428                 else {
 429                         lprintf(3, "SSL_accept failed: %s\n", ssl_error_reason);
 430                 }
 431                 sleeeeeeeeeep(1);
 432                 retval = SSL_accept(newssl);
 433         }
 434         if (retval < 1) {
 435                 long errval;
 436                 const char *ssl_error_reason = NULL;
 437
 438                 errval = SSL_get_error(newssl, retval);
 439                 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 440                 if (ssl_error_reason == NULL) {
 441                         lprintf(3, "SSL_accept failed: errval=%i, retval=%i (%s)\n", errval, retval, strerror(errval));
 442                 }
 443                 else {
 444                         lprintf(3, "SSL_accept failed: %s\n", ssl_error_reason);
 445                 }
 446                 SSL_free(newssl);
 447                 newssl = NULL;
 448                 return(4);
 449         }
 450         else {
 451                 lprintf(15, "SSL_accept success\n");
 452         }
 453         r = BIO_set_close(newssl->rbio, BIO_NOCLOSE);
 454         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(newssl), &alg_bits);
 455         lprintf(15, "SSL/TLS using %s on %s (%d of %d bits)\n",
 456                 SSL_CIPHER_get_name(SSL_get_current_cipher(newssl)),
 457                 SSL_CIPHER_get_version(SSL_get_current_cipher(newssl)),
 458                 bits, alg_bits);
 459
 460         pthread_setspecific(ThreadSSL, newssl);
 461         lprintf(15, "SSL started\n");
 462         return(0);
 463 }
 464
 465
 466
 467 /*
 468  * shuts down the TLS connection
 469  *
 470  * WARNING:  This may make your session vulnerable to a known plaintext
 471  * attack in the current implmentation.
 472  */
 473 void endtls(void)
 474 {
 475         SSL_CTX *ctx = NULL;
 476
 477         if (THREADSSL == NULL) return;
 478
 479         lprintf(15, "Ending SSL/TLS\n");
 480         SSL_shutdown(THREADSSL);
 481         ctx = SSL_get_SSL_CTX(THREADSSL);
 482
 483         /* I don't think this is needed, and it crashes the server anyway
 484          *
 485          *      if (ctx != NULL) {
 486          *              lprintf(9, "Freeing CTX at %x\n", (int)ctx );
 487          *              SSL_CTX_free(ctx);
 488          *      }
 489          */
 490
 491         SSL_free(THREADSSL);
 492         pthread_setspecific(ThreadSSL, NULL);
 493 }
 494
 495
 496 /*
 497  * callback for OpenSSL mutex locks
 498  */
 499 void ssl_lock(int mode, int n, const char *file, int line)
 500 {
 501         if (mode & CRYPTO_LOCK) {
 502                 pthread_mutex_lock(SSLCritters[n]);
 503         }
 504         else {
 505                 pthread_mutex_unlock(SSLCritters[n]);
 506         }
 507 }
 508
 509 /*
 510  * Send binary data to the client encrypted.
 511  */
 512 void client_write_ssl(const StrBuf *Buf)
 513 {
 514         const char *buf;
 515         int retval;
 516         int nremain;
 517         long nbytes;
 518         char junk[1];
 519
 520         if (THREADSSL == NULL) return;
 521
 522         nbytes = nremain = StrLength(Buf);
 523         buf = ChrPtr(Buf);
 524
 525         while (nremain > 0) {
 526                 if (SSL_want_write(THREADSSL)) {
 527                         if ((SSL_read(THREADSSL, junk, 0)) < 1) {
 528                                 lprintf(9, "SSL_read in client_write: %s\n",
 529                                                 ERR_reason_error_string(ERR_get_error()));
 530                         }
 531                 }
 532                 retval = SSL_write(THREADSSL, &buf[nbytes - nremain], nremain);
 533                 if (retval < 1) {
 534                         long errval;
 535
 536                         errval = SSL_get_error(THREADSSL, retval);
 537                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 538                                 sleeeeeeeeeep(1);
 539                                 continue;
 540                         }
 541                         lprintf(9, "SSL_write got error %ld, ret %d\n", errval, retval);
 542                         if (retval == -1) {
 543                                 lprintf(9, "errno is %d\n", errno);
 544                         }
 545                         endtls();
 546                         return;
 547                 }
 548                 nremain -= retval;
 549         }
 550 }
 551
 552
 553 /*
 554  * read data from the encrypted layer.
 555  */
 556 int client_read_sslbuffer(StrBuf *buf, int timeout)
 557 {
 558         char sbuf[16384]; /* OpenSSL communicates in 16k blocks, so let's speak its native tongue. */
 559         int rlen;
 560         char junk[1];
 561         SSL *pssl = THREADSSL;
 562
 563         if (pssl == NULL) return(-1);
 564
 565         while (1) {
 566                 if (SSL_want_read(pssl)) {
 567                         if ((SSL_write(pssl, junk, 0)) < 1) {
 568                                 lprintf(9, "SSL_write in client_read\n");
 569                         }
 570                 }
 571                 rlen = SSL_read(pssl, sbuf, sizeof(sbuf));
 572                 if (rlen < 1) {
 573                         long errval;
 574
 575                         errval = SSL_get_error(pssl, rlen);
 576                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 577                                 sleeeeeeeeeep(1);
 578                                 continue;
 579                         }
 580                         lprintf(9, "SSL_read got error %ld\n", errval);
 581                         endtls();
 582                         return (-1);
 583                 }
 584                 StrBufAppendBufPlain(buf, sbuf, rlen, 0);
 585                 return rlen;
 586         }
 587         return (0);
 588 }
 589
 590 #endif                          /* HAVE_OPENSSL */