webcit/crypto.c

   1 /*
   2  * Copyright (c) 1996-2012 by the citadel.org team
   3  *
   4  * This program is open source software.  You can redistribute it and/or
   5  * modify 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 "sysdep.h"
  14 #ifdef HAVE_OPENSSL
  15
  16 #include "webcit.h"
  17 #include "webserver.h"
  18
  19 /* where to find the keys */
  20 #define CTDL_CRYPTO_DIR         ctdl_key_dir
  21 #define CTDL_KEY_PATH           file_crpt_file_key
  22 #define CTDL_CSR_PATH           file_crpt_file_csr
  23 #define CTDL_CER_PATH           file_crpt_file_cer
  24 #define SIGN_DAYS               3650                    /* how long our certificate should live */
  25
  26 SSL_CTX *ssl_ctx;               /* SSL context */
  27 pthread_mutex_t **SSLCritters;  /* Things needing locking */
  28 char *ssl_cipher_list = DEFAULT_SSL_CIPHER_LIST;
  29
  30 pthread_key_t ThreadSSL;        /* Per-thread SSL context */
  31
  32 void ssl_lock(int mode, int n, const char *file, int line);
  33
  34 static unsigned long id_callback(void)
  35 {
  36         return (unsigned long) pthread_self();
  37 }
  38
  39 void shutdown_ssl(void)
  40 {
  41         ERR_free_strings();
  42
  43         /* Openssl requires these while shutdown.
  44          * Didn't find a way to get out of this clean.
  45          * int i, n = CRYPTO_num_locks();
  46          * for (i = 0; i < n; i++)
  47          *      free(SSLCritters[i]);
  48          * free(SSLCritters);
  49          */
  50 }
  51
  52 /*
  53  * initialize ssl engine, load certs and initialize openssl internals
  54  */
  55 void init_ssl(void)
  56 {
  57         const SSL_METHOD *ssl_method;
  58         RSA *rsa=NULL;
  59         X509_REQ *req = NULL;
  60         X509 *cer = NULL;
  61         EVP_PKEY *pk = NULL;
  62         EVP_PKEY *req_pkey = NULL;
  63         X509_NAME *name = NULL;
  64         FILE *fp;
  65         char buf[SIZ];
  66         int rv = 0;
  67
  68 #ifndef OPENSSL_NO_EGD
  69         if (!access("/var/run/egd-pool", F_OK)) {
  70                 RAND_egd("/var/run/egd-pool");
  71         }
  72 #endif
  73
  74         if (!RAND_status()) {
  75                 syslog(LOG_WARNING, "PRNG not adequately seeded, won't do SSL/TLS\n");
  76                 return;
  77         }
  78         SSLCritters = malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
  79         if (!SSLCritters) {
  80                 syslog(LOG_ERR, "citserver: can't allocate memory!!\n");
  81                 /* Nothing's been initialized, just die */
  82                 ShutDownWebcit();
  83                 exit(WC_EXIT_SSL);
  84         } else {
  85                 int a;
  86
  87                 for (a = 0; a < CRYPTO_num_locks(); a++) {
  88                         SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
  89                         if (!SSLCritters[a]) {
  90                                 syslog(LOG_ERR,
  91                                         "citserver: can't allocate memory!!\n");
  92                                 /** Nothing's been initialized, just die */
  93                                 ShutDownWebcit();
  94                                 exit(WC_EXIT_SSL);
  95                         }
  96                         pthread_mutex_init(SSLCritters[a], NULL);
  97                 }
  98         }
  99
 100         /*
 101          * Initialize SSL transport layer
 102          */
 103         SSL_library_init();
 104         SSL_load_error_strings();
 105         ssl_method = SSLv23_server_method();
 106         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
 107                 syslog(LOG_WARNING, "SSL_CTX_new failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 108                 return;
 109         }
 110
 111         syslog(LOG_INFO, "Requesting cipher list: %s\n", ssl_cipher_list);
 112         if (!(SSL_CTX_set_cipher_list(ssl_ctx, ssl_cipher_list))) {
 113                 syslog(LOG_WARNING, "SSL_CTX_set_cipher_list failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 114                 return;
 115         }
 116
 117         CRYPTO_set_locking_callback(ssl_lock);
 118         CRYPTO_set_id_callback(id_callback);
 119
 120         /*
 121          * Get our certificates in order. (FIXME: dirify. this is a setup job.)
 122          * First, create the key/cert directory if it's not there already...
 123          */
 124         mkdir(CTDL_CRYPTO_DIR, 0700);
 125
 126         /*
 127          * Before attempting to generate keys/certificates, first try
 128          * link to them from the Citadel server if it's on the same host.
 129          * We ignore any error return because it either meant that there
 130          * was nothing in Citadel to link from (in which case we just
 131          * generate new files) or the target files already exist (which
 132          * is not fatal either).
 133          */
 134         if (!strcasecmp(ctdlhost, "uds")) {
 135                 sprintf(buf, "%s/keys/citadel.key", ctdlport);
 136                 rv = symlink(buf, CTDL_KEY_PATH);
 137                 if (!rv) syslog(LOG_DEBUG, "%s\n", strerror(errno));
 138                 sprintf(buf, "%s/keys/citadel.csr", ctdlport);
 139                 rv = symlink(buf, CTDL_CSR_PATH);
 140                 if (!rv) syslog(LOG_DEBUG, "%s\n", strerror(errno));
 141                 sprintf(buf, "%s/keys/citadel.cer", ctdlport);
 142                 rv = symlink(buf, CTDL_CER_PATH);
 143                 if (!rv) syslog(LOG_DEBUG, "%s\n", strerror(errno));
 144         }
 145
 146         /*
 147          * If we still don't have a private key, generate one.
 148          */
 149         if (access(CTDL_KEY_PATH, R_OK) != 0) {
 150                 syslog(LOG_INFO, "Generating RSA key pair.\n");
 151                 rsa = RSA_generate_key(1024,    /* modulus size */
 152                                         65537,  /* exponent */
 153                                         NULL,   /* no callback */
 154                                         NULL    /* no callback */
 155                 );
 156                 if (rsa == NULL) {
 157                         syslog(LOG_WARNING, "Key generation failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 158                 }
 159                 if (rsa != NULL) {
 160                         fp = fopen(CTDL_KEY_PATH, "w");
 161                         if (fp != NULL) {
 162                                 chmod(CTDL_KEY_PATH, 0600);
 163                                 if (PEM_write_RSAPrivateKey(fp, /* the file */
 164                                                         rsa,    /* the key */
 165                                                         NULL,   /* no enc */
 166                                                         NULL,   /* no passphr */
 167                                                         0,      /* no passphr */
 168                                                         NULL,   /* no callbk */
 169                                                         NULL    /* no callbk */
 170                                 ) != 1) {
 171                                         syslog(LOG_WARNING, "Cannot write key: %s\n",
 172                                                 ERR_reason_error_string(ERR_get_error()));
 173                                         unlink(CTDL_KEY_PATH);
 174                                 }
 175                                 fclose(fp);
 176                         }
 177                         else {
 178                                 syslog(LOG_WARNING, "Cannot write key: %s\n", CTDL_KEY_PATH);
 179                                 ShutDownWebcit();
 180                                 exit(0);
 181                         }
 182                         RSA_free(rsa);
 183                 }
 184         }
 185
 186         /*
 187          * If there is no certificate file on disk, we will be generating a self-signed certificate
 188          * in the next step.  Therefore, if we have neither a CSR nor a certificate, generate
 189          * the CSR in this step so that the next step may commence.
 190          */
 191         if ( (access(CTDL_CER_PATH, R_OK) != 0) && (access(CTDL_CSR_PATH, R_OK) != 0) ) {
 192                 syslog(LOG_INFO, "Generating a certificate signing request.\n");
 193
 194                 /*
 195                  * Read our key from the file.  No, we don't just keep this
 196                  * in memory from the above key-generation function, because
 197                  * there is the possibility that the key was already on disk
 198                  * and we didn't just generate it now.
 199                  */
 200                 fp = fopen(CTDL_KEY_PATH, "r");
 201                 if (fp) {
 202                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 203                         fclose(fp);
 204                 }
 205
 206                 if (rsa) {
 207
 208                         /** Create a public key from the private key */
 209                         if (pk=EVP_PKEY_new(), pk != NULL) {
 210                                 EVP_PKEY_assign_RSA(pk, rsa);
 211                                 if (req = X509_REQ_new(), req != NULL) {
 212                                         const char *env;
 213                                         /* Set the public key */
 214                                         X509_REQ_set_pubkey(req, pk);
 215                                         X509_REQ_set_version(req, 0L);
 216
 217                                         name = X509_REQ_get_subject_name(req);
 218
 219                                         /* Tell it who we are */
 220
 221                                         /*
 222                                          * We used to add these fields to the subject, but
 223                                          * now we don't.  Someone doing this for real isn't
 224                                          * going to use the webcit-generated CSR anyway.
 225                                          *
 226                                         X509_NAME_add_entry_by_txt(name, "C",
 227                                                 MBSTRING_ASC, "US", -1, -1, 0);
 228                                         *
 229                                         X509_NAME_add_entry_by_txt(name, "ST",
 230                                                 MBSTRING_ASC, "New York", -1, -1, 0);
 231                                         *
 232                                         X509_NAME_add_entry_by_txt(name, "L",
 233                                                 MBSTRING_ASC, "Mount Kisco", -1, -1, 0);
 234                                         */
 235
 236                                         env = getenv("O");
 237                                         if (env == NULL)
 238                                                 env = "Organization name",
 239
 240                                         X509_NAME_add_entry_by_txt(
 241                                                 name, "O",
 242                                                 MBSTRING_ASC,
 243                                                 (unsigned char*)env,
 244                                                 -1, -1, 0
 245                                         );
 246
 247                                         env = getenv("OU");
 248                                         if (env == NULL)
 249                                                 env = "Citadel server";
 250
 251                                         X509_NAME_add_entry_by_txt(
 252                                                 name, "OU",
 253                                                 MBSTRING_ASC,
 254                                                 (unsigned char*)env,
 255                                                 -1, -1, 0
 256                                         );
 257
 258                                         env = getenv("CN");
 259                                         if (env == NULL)
 260                                                 env = "*";
 261
 262                                         X509_NAME_add_entry_by_txt(
 263                                                 name, "CN",
 264                                                 MBSTRING_ASC,
 265                                                 (unsigned char*)env,
 266                                                 -1, -1, 0
 267                                         );
 268
 269                                         X509_REQ_set_subject_name(req, name);
 270
 271                                         /* Sign the CSR */
 272                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 273                                                 syslog(LOG_WARNING, "X509_REQ_sign(): error\n");
 274                                         }
 275                                         else {
 276                                                 /* Write it to disk. */
 277                                                 fp = fopen(CTDL_CSR_PATH, "w");
 278                                                 if (fp != NULL) {
 279                                                         chmod(CTDL_CSR_PATH, 0600);
 280                                                         PEM_write_X509_REQ(fp, req);
 281                                                         fclose(fp);
 282                                                 }
 283                                                 else {
 284                                                         syslog(LOG_WARNING, "Cannot write key: %s\n", CTDL_CSR_PATH);
 285                                                         ShutDownWebcit();
 286                                                         exit(0);
 287                                                 }
 288                                         }
 289
 290                                         X509_REQ_free(req);
 291                                 }
 292                         }
 293
 294                         RSA_free(rsa);
 295                 }
 296
 297                 else {
 298                         syslog(LOG_WARNING, "Unable to read private key.\n");
 299                 }
 300         }
 301
 302
 303
 304         /*
 305          * Generate a self-signed certificate if we don't have one.
 306          */
 307         if (access(CTDL_CER_PATH, R_OK) != 0) {
 308                 syslog(LOG_INFO, "Generating a self-signed certificate.\n");
 309
 310                 /* Same deal as before: always read the key from disk because
 311                  * it may or may not have just been generated.
 312                  */
 313                 fp = fopen(CTDL_KEY_PATH, "r");
 314                 if (fp) {
 315                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 316                         fclose(fp);
 317                 }
 318
 319                 /* This also holds true for the CSR. */
 320                 req = NULL;
 321                 cer = NULL;
 322                 pk = NULL;
 323                 if (rsa) {
 324                         if (pk=EVP_PKEY_new(), pk != NULL) {
 325                                 EVP_PKEY_assign_RSA(pk, rsa);
 326                         }
 327
 328                         fp = fopen(CTDL_CSR_PATH, "r");
 329                         if (fp) {
 330                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 331                                 fclose(fp);
 332                         }
 333
 334                         if (req) {
 335                                 if (cer = X509_new(), cer != NULL) {
 336
 337                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 338                                         X509_set_issuer_name(cer, X509_REQ_get_subject_name(req));
 339                                         X509_set_subject_name(cer, X509_REQ_get_subject_name(req));
 340                                         X509_gmtime_adj(X509_get_notBefore(cer), 0);
 341                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 342
 343                                         req_pkey = X509_REQ_get_pubkey(req);
 344                                         X509_set_pubkey(cer, req_pkey);
 345                                         EVP_PKEY_free(req_pkey);
 346
 347                                         /* Sign the cert */
 348                                         if (!X509_sign(cer, pk, EVP_md5())) {
 349                                                 syslog(LOG_WARNING, "X509_sign(): error\n");
 350                                         }
 351                                         else {
 352                                                 /* Write it to disk. */
 353                                                 fp = fopen(CTDL_CER_PATH, "w");
 354                                                 if (fp != NULL) {
 355                                                         chmod(CTDL_CER_PATH, 0600);
 356                                                         PEM_write_X509(fp, cer);
 357                                                         fclose(fp);
 358                                                 }
 359                                                 else {
 360                                                         syslog(LOG_WARNING, "Cannot write key: %s\n", CTDL_CER_PATH);
 361                                                         ShutDownWebcit();
 362                                                         exit(0);
 363                                                 }
 364                                         }
 365                                         X509_free(cer);
 366                                 }
 367                         }
 368
 369                         RSA_free(rsa);
 370                 }
 371         }
 372
 373         /*
 374          * Now try to bind to the key and certificate.
 375          * Note that we use SSL_CTX_use_certificate_chain_file() which allows
 376          * the certificate file to contain intermediate certificates.
 377          */
 378         SSL_CTX_use_certificate_chain_file(ssl_ctx, CTDL_CER_PATH);
 379         SSL_CTX_use_PrivateKey_file(ssl_ctx, CTDL_KEY_PATH, SSL_FILETYPE_PEM);
 380         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 381                 syslog(LOG_WARNING, "Cannot install certificate: %s\n",
 382                                 ERR_reason_error_string(ERR_get_error()));
 383         }
 384
 385 }
 386
 387
 388 /*
 389  * starts SSL/TLS encryption for the current session.
 390  */
 391 int starttls(int sock) {
 392         int retval, bits, alg_bits;/*r; */
 393         SSL *newssl;
 394
 395         pthread_setspecific(ThreadSSL, NULL);
 396
 397         if (!ssl_ctx) {
 398                 return(1);
 399         }
 400         if (!(newssl = SSL_new(ssl_ctx))) {
 401                 syslog(LOG_WARNING, "SSL_new failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 402                 return(2);
 403         }
 404         if (!(SSL_set_fd(newssl, sock))) {
 405                 syslog(LOG_WARNING, "SSL_set_fd failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 406                 SSL_free(newssl);
 407                 return(3);
 408         }
 409         retval = SSL_accept(newssl);
 410         if (retval < 1) {
 411                 /*
 412                  * Can't notify the client of an error here; they will
 413                  * discover the problem at the SSL layer and should
 414                  * revert to unencrypted communications.
 415                  */
 416                 long errval;
 417                 const char *ssl_error_reason = NULL;
 418
 419                 errval = SSL_get_error(newssl, retval);
 420                 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 421                 if (ssl_error_reason == NULL) {
 422                         syslog(LOG_WARNING, "SSL_accept failed: errval=%ld, retval=%d %s\n", errval, retval, strerror(errval));
 423                 }
 424                 else {
 425                         syslog(LOG_WARNING, "SSL_accept failed: %s\n", ssl_error_reason);
 426                 }
 427                 sleeeeeeeeeep(1);
 428                 retval = SSL_accept(newssl);
 429         }
 430         if (retval < 1) {
 431                 long errval;
 432                 const char *ssl_error_reason = NULL;
 433
 434                 errval = SSL_get_error(newssl, retval);
 435                 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 436                 if (ssl_error_reason == NULL) {
 437                         syslog(LOG_WARNING, "SSL_accept failed: errval=%ld, retval=%d (%s)\n", errval, retval, strerror(errval));
 438                 }
 439                 else {
 440                         syslog(LOG_WARNING, "SSL_accept failed: %s\n", ssl_error_reason);
 441                 }
 442                 SSL_free(newssl);
 443                 newssl = NULL;
 444                 return(4);
 445         }
 446         else {
 447                 syslog(LOG_INFO, "SSL_accept success\n");
 448         }
 449         /*r = */BIO_set_close(SSL_get_rbio(newssl), BIO_NOCLOSE);
 450         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(newssl), &alg_bits);
 451         syslog(LOG_INFO, "SSL/TLS using %s on %s (%d of %d bits)\n",
 452                 SSL_CIPHER_get_name(SSL_get_current_cipher(newssl)),
 453                 SSL_CIPHER_get_version(SSL_get_current_cipher(newssl)),
 454                 bits, alg_bits);
 455
 456         pthread_setspecific(ThreadSSL, newssl);
 457         syslog(LOG_INFO, "SSL started\n");
 458         return(0);
 459 }
 460
 461
 462
 463 /*
 464  * shuts down the TLS connection
 465  *
 466  * WARNING:  This may make your session vulnerable to a known plaintext
 467  * attack in the current implmentation.
 468  */
 469 void endtls(void)
 470 {
 471         /*SSL_CTX *ctx;*/
 472
 473         if (THREADSSL == NULL) return;
 474
 475         syslog(LOG_INFO, "Ending SSL/TLS\n");
 476         SSL_shutdown(THREADSSL);
 477         /*ctx = */SSL_get_SSL_CTX(THREADSSL);
 478
 479         /* I don't think this is needed, and it crashes the server anyway
 480          *
 481          *      if (ctx != NULL) {
 482          *              syslog(LOG_DEBUG, "Freeing CTX at %x\n", (int)ctx );
 483          *              SSL_CTX_free(ctx);
 484          *      }
 485          */
 486
 487         SSL_free(THREADSSL);
 488         pthread_setspecific(ThreadSSL, NULL);
 489 }
 490
 491
 492 /*
 493  * callback for OpenSSL mutex locks
 494  */
 495 void ssl_lock(int mode, int n, const char *file, int line)
 496 {
 497         if (mode & CRYPTO_LOCK) {
 498                 pthread_mutex_lock(SSLCritters[n]);
 499         }
 500         else {
 501                 pthread_mutex_unlock(SSLCritters[n]);
 502         }
 503 }
 504
 505 /*
 506  * Send binary data to the client encrypted.
 507  */
 508 int client_write_ssl(const StrBuf *Buf)
 509 {
 510         const char *buf;
 511         int retval;
 512         int nremain;
 513         long nbytes;
 514         char junk[1];
 515
 516         if (THREADSSL == NULL) return -1;
 517
 518         nbytes = nremain = StrLength(Buf);
 519         buf = ChrPtr(Buf);
 520
 521         while (nremain > 0) {
 522                 if (SSL_want_write(THREADSSL)) {
 523                         if ((SSL_read(THREADSSL, junk, 0)) < 1) {
 524                                 syslog(LOG_WARNING, "SSL_read in client_write: %s\n",
 525                                                 ERR_reason_error_string(ERR_get_error()));
 526                         }
 527                 }
 528                 retval = SSL_write(THREADSSL, &buf[nbytes - nremain], nremain);
 529                 if (retval < 1) {
 530                         long errval;
 531
 532                         errval = SSL_get_error(THREADSSL, retval);
 533                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 534                                 sleeeeeeeeeep(1);
 535                                 continue;
 536                         }
 537                         syslog(LOG_WARNING, "SSL_write got error %ld, ret %d\n", errval, retval);
 538                         if (retval == -1) {
 539                                 syslog(LOG_WARNING, "errno is %d\n", errno);
 540                         }
 541                         endtls();
 542                         return -1;
 543                 }
 544                 nremain -= retval;
 545         }
 546         return 0;
 547 }
 548
 549
 550 /*
 551  * read data from the encrypted layer.
 552  */
 553 int client_read_sslbuffer(StrBuf *buf, int timeout)
 554 {
 555         char sbuf[16384]; /* OpenSSL communicates in 16k blocks, so let's speak its native tongue. */
 556         int rlen;
 557         char junk[1];
 558         SSL *pssl = THREADSSL;
 559
 560         if (pssl == NULL) return(-1);
 561
 562         while (1) {
 563                 if (SSL_want_read(pssl)) {
 564                         if ((SSL_write(pssl, junk, 0)) < 1) {
 565                                 syslog(LOG_WARNING, "SSL_write in client_read\n");
 566                         }
 567                 }
 568                 rlen = SSL_read(pssl, sbuf, sizeof(sbuf));
 569                 if (rlen < 1) {
 570                         long errval;
 571
 572                         errval = SSL_get_error(pssl, rlen);
 573                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 574                                 sleeeeeeeeeep(1);
 575                                 continue;
 576                         }
 577                         syslog(LOG_WARNING, "SSL_read got error %ld\n", errval);
 578                         endtls();
 579                         return (-1);
 580                 }
 581                 StrBufAppendBufPlain(buf, sbuf, rlen, 0);
 582                 return rlen;
 583         }
 584         return (0);
 585 }
 586
 587 #endif                          /* HAVE_OPENSSL */