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