webcit/crypto.c

   1 /*
   2  * $Id$
   3  */
   4 /**
   5  * \defgroup https  Provides HTTPS, when the OpenSSL library is available.
   6  * \ingroup WebcitHttpServer
   7  */
   8
   9 /*@{*/
  10 #include "sysdep.h"
  11 #ifdef HAVE_OPENSSL
  12
  13 #include "webcit.h"
  14 #include "webserver.h"
  15 /** \todo dirify */
  16 /** where to find the keys */
  17 #define CTDL_CRYPTO_DIR         ctdl_key_dir
  18 #define CTDL_KEY_PATH           file_crpt_file_key /**< the key */
  19 #define CTDL_CSR_PATH           file_crpt_file_csr /**< the csr file */
  20 #define CTDL_CER_PATH           file_crpt_file_cer /**< the cer file */
  21 #define SIGN_DAYS               365 /**< how long our certificate should live */
  22
  23 SSL_CTX *ssl_ctx;               /**< SSL context */
  24 pthread_mutex_t **SSLCritters;  /**< Things needing locking */
  25
  26 pthread_key_t ThreadSSL;        /**< Per-thread SSL context */
  27
  28 /**
  29  * \brief what?????
  30  * \return thread id???
  31  */
  32 static unsigned long id_callback(void)
  33 {
  34         return (unsigned long) pthread_self();
  35 }
  36
  37 void shutdown_ssl(void)
  38 {
  39         ERR_free_strings();
  40
  41         /* Openssl requires these while shutdown.
  42          * Didn't find a way to get out of this clean.
  43          * int i, n = CRYPTO_num_locks();
  44          * for (i = 0; i < n; i++)
  45          *      free(SSLCritters[i]);
  46          * free(SSLCritters);
  47         */
  48 }
  49
  50 /**
  51  * \brief initialize ssl engine
  52  * load certs and initialize openssl internals
  53  */
  54 void init_ssl(void)
  55 {
  56         SSL_METHOD *ssl_method;
  57         RSA *rsa=NULL;
  58         X509_REQ *req = NULL;
  59         X509 *cer = NULL;
  60         EVP_PKEY *pk = NULL;
  61         EVP_PKEY *req_pkey = NULL;
  62         X509_NAME *name = NULL;
  63         FILE *fp;
  64         char buf[SIZ];
  65
  66         if (!access("/var/run/egd-pool", F_OK))
  67                 RAND_egd("/var/run/egd-pool");
  68
  69         if (!RAND_status()) {
  70                 lprintf(3,
  71                         "PRNG not adequately seeded, won't do SSL/TLS\n");
  72                 return;
  73         }
  74         SSLCritters =
  75             malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
  76         if (!SSLCritters) {
  77                 lprintf(1, "citserver: can't allocate memory!!\n");
  78                 /* Nothing's been initialized, just die */
  79                 ShutDownWebcit();
  80                 exit(WC_EXIT_SSL);
  81         } else {
  82                 int a;
  83
  84                 for (a = 0; a < CRYPTO_num_locks(); a++) {
  85                         SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
  86                         if (!SSLCritters[a]) {
  87                                 lprintf(1,
  88                                         "citserver: can't allocate memory!!\n");
  89                                 /** Nothing's been initialized, just die */
  90                                 ShutDownWebcit();
  91                                 exit(WC_EXIT_SSL);
  92                         }
  93                         pthread_mutex_init(SSLCritters[a], NULL);
  94                 }
  95         }
  96
  97         /**
  98          * Initialize SSL transport layer
  99          */
 100         SSL_library_init();
 101         SSL_load_error_strings();
 102         ssl_method = SSLv23_server_method();
 103         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
 104                 lprintf(3, "SSL_CTX_new failed: %s\n",
 105                         ERR_reason_error_string(ERR_get_error()));
 106                 return;
 107         }
 108
 109         CRYPTO_set_locking_callback(ssl_lock);
 110         CRYPTO_set_id_callback(id_callback);
 111
 112         /**
 113          * Get our certificates in order. \todo dirify. this is a setup job.
 114          * First, create the key/cert directory if it's not there already...
 115          */
 116         mkdir(CTDL_CRYPTO_DIR, 0700);
 117
 118         /**
 119          * Before attempting to generate keys/certificates, first try
 120          * link to them from the Citadel server if it's on the same host.
 121          * We ignore any error return because it either meant that there
 122          * was nothing in Citadel to link from (in which case we just
 123          * generate new files) or the target files already exist (which
 124          * is not fatal either). \todo dirify
 125          */
 126         if (!strcasecmp(ctdlhost, "uds")) {
 127                 sprintf(buf, "%s/keys/citadel.key", ctdlport);
 128                 symlink(buf, CTDL_KEY_PATH);
 129                 sprintf(buf, "%s/keys/citadel.csr", ctdlport);
 130                 symlink(buf, CTDL_CSR_PATH);
 131                 sprintf(buf, "%s/keys/citadel.cer", ctdlport);
 132                 symlink(buf, CTDL_CER_PATH);
 133         }
 134
 135         /**
 136          * If we still don't have a private key, generate one.
 137          */
 138         if (access(CTDL_KEY_PATH, R_OK) != 0) {
 139                 lprintf(5, "Generating RSA key pair.\n");
 140                 rsa = RSA_generate_key(1024,    /**< modulus size */
 141                                         65537,  /**< exponent */
 142                                         NULL,   /**< no callback */
 143                                         NULL);  /**< no callback */
 144                 if (rsa == NULL) {
 145                         lprintf(3, "Key generation failed: %s\n",
 146                                 ERR_reason_error_string(ERR_get_error()));
 147                 }
 148                 if (rsa != NULL) {
 149                         fp = fopen(CTDL_KEY_PATH, "w");
 150                         if (fp != NULL) {
 151                                 chmod(CTDL_KEY_PATH, 0600);
 152                                 if (PEM_write_RSAPrivateKey(fp, /**< the file */
 153                                                         rsa,    /**< the key */
 154                                                         NULL,   /**< no enc */
 155                                                         NULL,   /**< no passphr */
 156                                                         0,      /**< no passphr */
 157                                                         NULL,   /**< no callbk */
 158                                                         NULL    /**< no callbk */
 159                                 ) != 1) {
 160                                         lprintf(3, "Cannot write key: %s\n",
 161                                                 ERR_reason_error_string(ERR_get_error()));
 162                                         unlink(CTDL_KEY_PATH);
 163                                 }
 164                                 fclose(fp);
 165                         }
 166                         else {
 167                                 lprintf(3, "Cannot write key: %s\n", CTDL_KEY_PATH);
 168                                 ShutDownWebcit();
 169                                 exit(0);
 170                         }
 171                         RSA_free(rsa);
 172                 }
 173         }
 174
 175         /*
 176          * If there is no certificate file on disk, we will be generating a self-signed certificate
 177          * in the next step.  Therefore, if we have neither a CSR nor a certificate, generate
 178          * the CSR in this step so that the next step may commence.
 179          */
 180         if ( (access(CTDL_CER_PATH, R_OK) != 0) && (access(CTDL_CSR_PATH, R_OK) != 0) ) {
 181                 lprintf(5, "Generating a certificate signing request.\n");
 182
 183                 /**
 184                  * Read our key from the file.  No, we don't just keep this
 185                  * in memory from the above key-generation function, because
 186                  * there is the possibility that the key was already on disk
 187                  * and we didn't just generate it now.
 188                  */
 189                 fp = fopen(CTDL_KEY_PATH, "r");
 190                 if (fp) {
 191                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 192                         fclose(fp);
 193                 }
 194
 195                 if (rsa) {
 196
 197                         /** Create a public key from the private key */
 198                         if (pk=EVP_PKEY_new(), pk != NULL) {
 199                                 EVP_PKEY_assign_RSA(pk, rsa);
 200                                 if (req = X509_REQ_new(), req != NULL) {
 201
 202                                         /** Set the public key */
 203                                         X509_REQ_set_pubkey(req, pk);
 204                                         X509_REQ_set_version(req, 0L);
 205
 206                                         name = X509_REQ_get_subject_name(req);
 207
 208                                         /** Tell it who we are */
 209
 210                                         /* \todo whats this?
 211                                         X509_NAME_add_entry_by_txt(name, "C",
 212                                                 MBSTRING_ASC, "US", -1, -1, 0);
 213
 214                                         X509_NAME_add_entry_by_txt(name, "ST",
 215                                                 MBSTRING_ASC, "New York", -1, -1, 0);
 216
 217                                         X509_NAME_add_entry_by_txt(name, "L",
 218                                                 MBSTRING_ASC, "Mount Kisco", -1, -1, 0);
 219                                         */
 220
 221                                         X509_NAME_add_entry_by_txt(
 222                                                 name, "O",
 223                                                 MBSTRING_ASC,
 224                                                 (unsigned char*)"Organization name",
 225                                                 -1, -1, 0);
 226
 227                                         X509_NAME_add_entry_by_txt(
 228                                                 name, "OU",
 229                                                 MBSTRING_ASC,
 230                                                 (unsigned char*)"Citadel server1",
 231                                                 -1, -1, 0);
 232
 233                                         X509_NAME_add_entry_by_txt(
 234                                                 name, "CN",
 235                                                 MBSTRING_ASC,
 236                                                 (unsigned char*)"*", -1, -1, 0);
 237
 238                                         X509_REQ_set_subject_name(req, name);
 239
 240                                         /** Sign the CSR */
 241                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 242                                                 lprintf(3, "X509_REQ_sign(): error\n");
 243                                         }
 244                                         else {
 245                                                 /** Write it to disk. */
 246                                                 fp = fopen(CTDL_CSR_PATH, "w");
 247                                                 if (fp != NULL) {
 248                                                         chmod(CTDL_CSR_PATH, 0600);
 249                                                         PEM_write_X509_REQ(fp, req);
 250                                                         fclose(fp);
 251                                                 }
 252                                                 else {
 253                                                         lprintf(3, "Cannot write key: %s\n", CTDL_CSR_PATH);
 254                                                         ShutDownWebcit();
 255                                                         exit(0);
 256                                                 }
 257                                         }
 258
 259                                         X509_REQ_free(req);
 260                                 }
 261                         }
 262
 263                         RSA_free(rsa);
 264                 }
 265
 266                 else {
 267                         lprintf(3, "Unable to read private key.\n");
 268                 }
 269         }
 270
 271
 272
 273         /**
 274          * Generate a self-signed certificate if we don't have one.
 275          */
 276         if (access(CTDL_CER_PATH, R_OK) != 0) {
 277                 lprintf(5, "Generating a self-signed certificate.\n");
 278
 279                 /** Same deal as before: always read the key from disk because
 280                  * it may or may not have just been generated.
 281                  */
 282                 fp = fopen(CTDL_KEY_PATH, "r");
 283                 if (fp) {
 284                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 285                         fclose(fp);
 286                 }
 287
 288                 /** This also holds true for the CSR. */
 289                 req = NULL;
 290                 cer = NULL;
 291                 pk = NULL;
 292                 if (rsa) {
 293                         if (pk=EVP_PKEY_new(), pk != NULL) {
 294                                 EVP_PKEY_assign_RSA(pk, rsa);
 295                         }
 296
 297                         fp = fopen(CTDL_CSR_PATH, "r");
 298                         if (fp) {
 299                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 300                                 fclose(fp);
 301                         }
 302
 303                         if (req) {
 304                                 if (cer = X509_new(), cer != NULL) {
 305
 306                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 307                                         X509_set_issuer_name(cer, req->req_info->subject);
 308                                         X509_set_subject_name(cer, req->req_info->subject);
 309                                         X509_gmtime_adj(X509_get_notBefore(cer), 0);
 310                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 311
 312                                         req_pkey = X509_REQ_get_pubkey(req);
 313                                         X509_set_pubkey(cer, req_pkey);
 314                                         EVP_PKEY_free(req_pkey);
 315
 316                                         /** Sign the cert */
 317                                         if (!X509_sign(cer, pk, EVP_md5())) {
 318                                                 lprintf(3, "X509_sign(): error\n");
 319                                         }
 320                                         else {
 321                                                 /** Write it to disk. */
 322                                                 fp = fopen(CTDL_CER_PATH, "w");
 323                                                 if (fp != NULL) {
 324                                                         chmod(CTDL_CER_PATH, 0600);
 325                                                         PEM_write_X509(fp, cer);
 326                                                         fclose(fp);
 327                                                 }
 328                                                 else {
 329                                                         lprintf(3, "Cannot write key: %s\n", CTDL_CER_PATH);
 330                                                         ShutDownWebcit();
 331                                                         exit(0);
 332                                                 }
 333                                         }
 334                                         X509_free(cer);
 335                                 }
 336                         }
 337
 338                         RSA_free(rsa);
 339                 }
 340         }
 341
 342         /**
 343          * Now try to bind to the key and certificate.
 344          * Note that we use SSL_CTX_use_certificate_chain_file() which allows
 345          * the certificate file to contain intermediate certificates.
 346          */
 347         SSL_CTX_use_certificate_chain_file(ssl_ctx, CTDL_CER_PATH);
 348         SSL_CTX_use_PrivateKey_file(ssl_ctx, CTDL_KEY_PATH, SSL_FILETYPE_PEM);
 349         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 350                 lprintf(3, "Cannot install certificate: %s\n",
 351                                 ERR_reason_error_string(ERR_get_error()));
 352         }
 353
 354 }
 355
 356
 357 /**
 358  * \brief starts SSL/TLS encryption for the current session.
 359  * \param sock the socket connection
 360  * \return Zero if the SSL/TLS handshake succeeded, non-zero otherwise.
 361  */
 362 int starttls(int sock) {
 363         int retval, bits, alg_bits, r;
 364         SSL *newssl;
 365
 366         pthread_setspecific(ThreadSSL, NULL);
 367
 368         if (!ssl_ctx) {
 369                 return(1);
 370         }
 371         if (!(newssl = SSL_new(ssl_ctx))) {
 372                 lprintf(3, "SSL_new failed: %s\n",
 373                                 ERR_reason_error_string(ERR_get_error()));
 374                 return(2);
 375         }
 376         if (!(SSL_set_fd(newssl, sock))) {
 377                 lprintf(3, "SSL_set_fd failed: %s\n",
 378                         ERR_reason_error_string(ERR_get_error()));
 379                 SSL_free(newssl);
 380                 return(3);
 381         }
 382         retval = SSL_accept(newssl);
 383         if (retval < 1) {
 384                 /**
 385                  * Can't notify the client of an error here; they will
 386                  * discover the problem at the SSL layer and should
 387                  * revert to unencrypted communications.
 388                  */
 389                 long errval;
 390                 const char *ssl_error_reason = NULL;
 391
 392                 errval = SSL_get_error(newssl, retval);
 393                 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 394                 if (ssl_error_reason == NULL)
 395                         lprintf(3, "SSL_accept failed: errval=%i, retval=%i\n", errval, retval);
 396                 else
 397                         lprintf(3, "SSL_accept failed: %s\n", ssl_error_reason);
 398                 sleep(1);
 399                 retval = SSL_accept(newssl);
 400         }
 401         if (retval < 1) {
 402                 long errval;
 403                 const char *ssl_error_reason = NULL;
 404
 405                 errval = SSL_get_error(newssl, retval);
 406                 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 407                 if (ssl_error_reason == NULL)
 408                         lprintf(3, "SSL_accept failed: errval=%i, retval=%i\n", errval, retval);
 409                 else
 410                         lprintf(3, "SSL_accept failed: %s\n", ssl_error_reason);
 411                 SSL_free(newssl);
 412                 newssl = NULL;
 413                 return(4);
 414         } else lprintf(15, "SSL_accept success\n");
 415         r = BIO_set_close(newssl->rbio, BIO_NOCLOSE);
 416         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(newssl), &alg_bits);
 417         lprintf(15, "SSL/TLS using %s on %s (%d of %d bits)\n",
 418                 SSL_CIPHER_get_name(SSL_get_current_cipher(newssl)),
 419                 SSL_CIPHER_get_version(SSL_get_current_cipher(newssl)),
 420                 bits, alg_bits);
 421
 422         pthread_setspecific(ThreadSSL, newssl);
 423         lprintf(15, "SSL started\n");
 424         return(0);
 425 }
 426
 427
 428
 429 /**
 430  * \brief shuts down the TLS connection
 431  *
 432  * WARNING:  This may make your session vulnerable to a known plaintext
 433  * attack in the current implmentation.
 434  */
 435 void endtls(void)
 436 {
 437         SSL_CTX *ctx = NULL;
 438
 439         if (THREADSSL == NULL) return;
 440
 441         lprintf(15, "Ending SSL/TLS\n");
 442         SSL_shutdown(THREADSSL);
 443         ctx = SSL_get_SSL_CTX(THREADSSL);
 444
 445         /** I don't think this is needed, and it crashes the server anyway
 446          *
 447          *      if (ctx != NULL) {
 448          *              lprintf(9, "Freeing CTX at %x\n", (int)ctx );
 449          *              SSL_CTX_free(ctx);
 450          *      }
 451          */
 452
 453         SSL_free(THREADSSL);
 454         pthread_setspecific(ThreadSSL, NULL);
 455 }
 456
 457
 458 /**
 459  * \brief callback for OpenSSL mutex locks
 460  * \param mode which mode??????
 461  * \param n  how many???
 462  * \param file which filename ???
 463  * \param line what line????
 464  */
 465 void ssl_lock(int mode, int n, const char *file, int line)
 466 {
 467         if (mode & CRYPTO_LOCK)
 468                 pthread_mutex_lock(SSLCritters[n]);
 469         else
 470                 pthread_mutex_unlock(SSLCritters[n]);
 471 }
 472
 473 /**
 474  * \brief Send binary data to the client encrypted.
 475  * \param buf chars to send to the client
 476  * \param nbytes how many chars
 477  */
 478 void client_write_ssl(const StrBuf *Buf)
 479 {
 480         const char *buf;
 481         int retval;
 482         int nremain;
 483         long nbytes;
 484         char junk[1];
 485
 486         if (THREADSSL == NULL) return;
 487
 488         nbytes = nremain = StrLength(Buf);
 489         buf = ChrPtr(Buf);
 490
 491         while (nremain > 0) {
 492                 if (SSL_want_write(THREADSSL)) {
 493                         if ((SSL_read(THREADSSL, junk, 0)) < 1) {
 494                                 lprintf(9, "SSL_read in client_write: %s\n",
 495                                                 ERR_reason_error_string(ERR_get_error()));
 496                         }
 497                 }
 498                 retval = SSL_write(THREADSSL, &buf[nbytes - nremain], nremain);
 499                 if (retval < 1) {
 500                         long errval;
 501
 502                         errval = SSL_get_error(THREADSSL, retval);
 503                         if (errval == SSL_ERROR_WANT_READ ||
 504                             errval == SSL_ERROR_WANT_WRITE) {
 505                                 sleep(1);
 506                                 continue;
 507                         }
 508                         lprintf(9, "SSL_write got error %ld, ret %d\n", errval, retval);
 509                         if (retval == -1) {
 510                                 lprintf(9, "errno is %d\n", errno);
 511                         }
 512                         endtls();
 513                         return;
 514                 }
 515                 nremain -= retval;
 516         }
 517 }
 518
 519
 520 /**
 521  * \brief read data from the encrypted layer.
 522  * \param buf charbuffer to read to
 523  * \param bytes how many
 524  * \param timeout how long should we wait?
 525  * \returns what???
 526  */
 527 int client_read_sslbuffer(StrBuf *buf, int timeout)
 528 {
 529 #if 0
 530         fd_set rfds;
 531         struct timeval tv;
 532         int retval;
 533         int s;
 534 #endif
 535         char sbuf[16384]; /**< Openssl communicates in 16k blocks, so lets speak its native tongue. */
 536         int rlen;
 537         char junk[1];
 538
 539         if (THREADSSL == NULL) return(0);
 540
 541         while (1) {
 542 #if 0
 543                 /**
 544                  * This code is disabled because we don't need it when
 545                  * using blocking reads (which we are). -IO
 546                  */
 547                 FD_ZERO(&rfds);
 548                 s = BIO_get_fd(THREADSSL->rbio, NULL);
 549                 FD_SET(s, &rfds);
 550                 tv.tv_sec = timeout;
 551                 tv.tv_usec = 0;
 552
 553                 retval = select(s + 1, &rfds, NULL, NULL, &tv);
 554
 555                 if (FD_ISSET(s, &rfds) == 0) {
 556                         return (0);
 557                 }
 558
 559 #endif
 560                 if (SSL_want_read(THREADSSL)) {
 561                         if ((SSL_write(THREADSSL, junk, 0)) < 1) {
 562                                 lprintf(9, "SSL_write in client_read\n");
 563                         }
 564                 }
 565                 rlen = SSL_read(THREADSSL, sbuf, sizeof(sbuf));
 566                 if (rlen < 1) {
 567                         long errval;
 568
 569                         errval = SSL_get_error(THREADSSL, rlen);
 570                         if (errval == SSL_ERROR_WANT_READ ||
 571                             errval == SSL_ERROR_WANT_WRITE) {
 572                                 sleep(1);
 573                                 continue;
 574                         }
 575                         lprintf(9, "SSL_read got error %ld\n", errval);
 576                         endtls();
 577                         return (0);
 578                 }
 579                 StrBufAppendBufPlain(buf, sbuf, rlen, 0);
 580                 return(1);
 581         }
 582         return (1);
 583 }
 584
 585
 586 #endif                          /* HAVE_OPENSSL */
 587 /*@}*/