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