citadel/serv_crypto.c

   1 /* $Id$ */
   2
   3 #include <string.h>
   4 #include <unistd.h>
   5 #include <sys/stat.h>
   6 #include <sys/types.h>
   7 #include "sysdep.h"
   8
   9 #ifdef HAVE_OPENSSL
  10 #include <openssl/ssl.h>
  11 #include <openssl/err.h>
  12 #include <openssl/rand.h>
  13 #endif
  14
  15 #if TIME_WITH_SYS_TIME
  16 # include <sys/time.h>
  17 # include <time.h>
  18 #else
  19 # if HAVE_SYS_TIME_H
  20 #  include <sys/time.h>
  21 # else
  22 #  include <time.h>
  23 # endif
  24 #endif
  25
  26 #ifdef HAVE_PTHREAD_H
  27 #include <pthread.h>
  28 #endif
  29
  30 #ifdef HAVE_SYS_SELECT_H
  31 #include <sys/select.h>
  32 #endif
  33
  34 #include <stdio.h>
  35 #include "server.h"
  36 #include "serv_crypto.h"
  37 #include "sysdep_decls.h"
  38 #include "serv_extensions.h"
  39 #include "citadel.h"
  40 #include "config.h"
  41
  42
  43 #ifdef HAVE_OPENSSL
  44 SSL_CTX *ssl_ctx;               /* SSL context */
  45 pthread_mutex_t **SSLCritters;  /* Things needing locking */
  46
  47 static unsigned long id_callback(void)
  48 {
  49         return (unsigned long) pthread_self();
  50 }
  51
  52  /*
  53   * Set up the cert things on the server side. We do need both the
  54   * private key (in key_file) and the cert (in cert_file).
  55   * Both files may be identical.
  56   *
  57   * This function is taken from OpenSSL apps/s_cb.c
  58   */
  59
  60 static int ctdl_install_certificate(SSL_CTX * ctx,
  61                           const char *cert_file, const char *key_file)
  62 {
  63         if (cert_file != NULL) {
  64                 if (SSL_CTX_use_certificate_file(ctx, cert_file,
  65                                                  SSL_FILETYPE_PEM) <= 0) {
  66                         lprintf(3, "unable to get certificate from '%s'",
  67                                 cert_file);
  68                         return (0);
  69                 }
  70                 if (key_file == NULL)
  71                         key_file = cert_file;
  72                 if (SSL_CTX_use_PrivateKey_file(ctx, key_file,
  73                                                 SSL_FILETYPE_PEM) <= 0) {
  74                         lprintf(3, "unable to get private key from '%s'",
  75                                 key_file);
  76                         return (0);
  77                 }
  78                 /* Now we know that a key and cert have been set against
  79                  * the SSL context */
  80                 if (!SSL_CTX_check_private_key(ctx)) {
  81                         lprintf(3,
  82                                 "Private key does not match the certificate public key");
  83                         return (0);
  84                 }
  85         }
  86         return (1);
  87 }
  88
  89
  90 void init_ssl(void)
  91 {
  92         SSL_METHOD *ssl_method;
  93         DH *dh;
  94         RSA *rsa=NULL;
  95         X509_REQ *x = NULL;
  96         EVP_PKEY *pk = NULL;
  97         X509_NAME *name = NULL;
  98         FILE *fp;
  99
 100         if (!access("/var/run/egd-pool", F_OK))
 101                 RAND_egd("/var/run/egd-pool");
 102
 103         if (!RAND_status()) {
 104                 lprintf(2,
 105                         "PRNG not adequately seeded, won't do SSL/TLS\n");
 106                 return;
 107         }
 108         SSLCritters =
 109             mallok(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
 110         if (!SSLCritters) {
 111                 lprintf(1, "citserver: can't allocate memory!!\n");
 112                 /* Nothing's been initialized, just die */
 113                 exit(1);
 114         } else {
 115                 int a;
 116
 117                 for (a = 0; a < CRYPTO_num_locks(); a++) {
 118                         SSLCritters[a] = mallok(sizeof(pthread_mutex_t));
 119                         if (!SSLCritters[a]) {
 120                                 lprintf(1,
 121                                         "citserver: can't allocate memory!!\n");
 122                                 /* Nothing's been initialized, just die */
 123                                 exit(1);
 124                         }
 125                         pthread_mutex_init(SSLCritters[a], NULL);
 126                 }
 127         }
 128
 129         /*
 130          * Initialize SSL transport layer
 131          */
 132         SSL_library_init();
 133         SSL_load_error_strings();
 134         ssl_method = SSLv23_server_method();
 135         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
 136                 lprintf(2, "SSL_CTX_new failed: %s\n",
 137                         ERR_reason_error_string(ERR_get_error()));
 138                 return;
 139         }
 140         if (!(SSL_CTX_set_cipher_list(ssl_ctx, CIT_CIPHERS))) {
 141                 lprintf(2, "SSL: No ciphers available\n");
 142                 SSL_CTX_free(ssl_ctx);
 143                 ssl_ctx = NULL;
 144                 return;
 145         }
 146 #if 0
 147 #if SSLEAY_VERSION_NUMBER >= 0x00906000L
 148         SSL_CTX_set_mode(ssl_ctx, SSL_CTX_get_mode(ssl_ctx) |
 149                          SSL_MODE_AUTO_RETRY);
 150 #endif
 151 #endif
 152
 153         CRYPTO_set_locking_callback(ssl_lock);
 154         CRYPTO_set_id_callback(id_callback);
 155
 156         /* Load DH parameters into the context */
 157         dh = DH_new();
 158         if (!dh) {
 159                 lprintf(2, "init_ssl() can't allocate a DH object: %s\n",
 160                         ERR_reason_error_string(ERR_get_error()));
 161                 SSL_CTX_free(ssl_ctx);
 162                 ssl_ctx = NULL;
 163                 return;
 164         }
 165         if (!(BN_hex2bn(&(dh->p), DH_P))) {
 166                 lprintf(2, "init_ssl() can't assign DH_P: %s\n",
 167                         ERR_reason_error_string(ERR_get_error()));
 168                 SSL_CTX_free(ssl_ctx);
 169                 ssl_ctx = NULL;
 170                 return;
 171         }
 172         if (!(BN_hex2bn(&(dh->g), DH_G))) {
 173                 lprintf(2, "init_ssl() can't assign DH_G: %s\n",
 174                         ERR_reason_error_string(ERR_get_error()));
 175                 SSL_CTX_free(ssl_ctx);
 176                 ssl_ctx = NULL;
 177                 return;
 178         }
 179         dh->length = DH_L;
 180         SSL_CTX_set_tmp_dh(ssl_ctx, dh);
 181         DH_free(dh);
 182
 183         /* Get our certificates in order.
 184          * First, create the key/cert directory if it's not there already...
 185          */
 186         mkdir(CTDL_CRYPTO_DIR, 0700);
 187
 188         /*
 189          * Generate a key pair if we don't have one.
 190          */
 191         if (access(CTDL_KEY_PATH, R_OK) != 0) {
 192                 lprintf(3, "Generating RSA key pair.\n");
 193                 rsa = RSA_generate_key(1024,    /* modulus size */
 194                                         65537,  /* exponent */
 195                                         NULL,   /* no callback */
 196                                         NULL);  /* no callback */
 197                 if (rsa == NULL) {
 198                         lprintf(2, "Key generation failed: %s\n",
 199                                 ERR_reason_error_string(ERR_get_error()));
 200                 }
 201                 if (rsa != NULL) {
 202                         fp = fopen(CTDL_KEY_PATH, "w");
 203                         if (fp != NULL) {
 204                                 chmod(CTDL_KEY_PATH, 0600);
 205                                 if (PEM_write_RSAPrivateKey(fp, /* the file */
 206                                                         rsa,    /* the key */
 207                                                         NULL,   /* no enc */
 208                                                         NULL,   /* no passphr */
 209                                                         0,      /* no passphr */
 210                                                         NULL,   /* no callbk */
 211                                                         NULL    /* no callbk */
 212                                 ) != 1) {
 213                                         lprintf(2, "Cannot write key: %s\n",
 214                                                 ERR_reason_error_string(ERR_get_error()));
 215                                         unlink(CTDL_KEY_PATH);
 216                                 }
 217                                 fclose(fp);
 218                         }
 219                         RSA_free(rsa);
 220                 }
 221         }
 222
 223         /*
 224          * Generate a CSR if we don't have one.
 225          */
 226         if (access(CTDL_CSR_PATH, R_OK) != 0) {
 227                 lprintf(3, "Generating a certificate signing request.\n");
 228
 229                 /*
 230                  * Read our key from the file.  No, we don't just keep this
 231                  * in memory from the above key-generation function, because
 232                  * there is the possibility that the key was already on disk
 233                  * and we didn't just generate it now.
 234                  */
 235                 fp = fopen(CTDL_KEY_PATH, "r");
 236                 if (fp) {
 237                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 238                         fclose(fp);
 239                 }
 240
 241                 if (rsa) {
 242
 243                         /* Create a public key from the private key */
 244                         if (pk=EVP_PKEY_new(), pk != NULL) {
 245                                 EVP_PKEY_assign_RSA(pk, rsa);
 246                                 if (x = X509_REQ_new(), x != NULL) {
 247
 248                                         /* Set the public key */
 249                                         X509_REQ_set_pubkey(x, pk);
 250                                         X509_REQ_set_version(x, 0L);
 251
 252                                         name = X509_REQ_get_subject_name(x);
 253
 254                                         /* Tell it who we are (FIXME more here later) */
 255                                         X509_NAME_add_entry_by_txt(name, "C",
 256                                                 MBSTRING_ASC, "US", -1, -1, 0);
 257
 258                                         X509_NAME_add_entry_by_txt(name, "CN",
 259                                                 MBSTRING_ASC, config.c_fqdn, -1, -1, 0);
 260
 261                                         X509_REQ_set_subject_name(x, name);
 262
 263                                         /* Sign the CSR */
 264                                         if (!X509_REQ_sign(x, pk, EVP_md5())) {
 265                                                 lprintf(3, "X509_REQ_sign(): error\n");
 266                                         }
 267                                         else {
 268                                                 /* Write it to disk. */
 269                                                 fp = fopen(CTDL_CSR_PATH, "w");
 270                                                 if (fp != NULL) {
 271                                                         chmod(CTDL_CSR_PATH, 0600);
 272                                                         PEM_write_X509_REQ(fp, x);
 273                                                         fclose(fp);
 274                                                 }
 275                                         }
 276
 277                                         X509_REQ_free(x);
 278                                 }
 279                         }
 280
 281                         RSA_free(rsa);
 282                 }
 283
 284                 else {
 285                         lprintf(3, "Unable to read private key.\n");
 286                 }
 287         }
 288
 289
 290
 291         /*
 292          * Generate a self-signed certificate if we don't have one.
 293          */
 294         if (access(CTDL_CER_PATH, R_OK) != 0) {
 295                 lprintf(3, "Generating a self-signed certificate.\n");
 296
 297
 298                 /* FIXME ... do it */
 299         }
 300
 301
 302         /*
 303          * Now try to bind to the key and certificate.
 304          */
 305         if (ctdl_install_certificate(ssl_ctx,
 306                         CTDL_CER_PATH,
 307                         CTDL_KEY_PATH) != 1)
 308         {
 309                 lprintf(2, "Cannot install certificate: %s\n",
 310                                 ERR_reason_error_string(ERR_get_error()));
 311         }
 312
 313         /* Finally let the server know we're here */
 314         CtdlRegisterProtoHook(cmd_stls, "STLS", "Start SSL/TLS session");
 315         CtdlRegisterProtoHook(cmd_gtls, "GTLS",
 316                               "Get SSL/TLS session status");
 317         CtdlRegisterSessionHook(endtls, EVT_STOP);
 318 }
 319
 320
 321 /*
 322  * client_write_ssl() Send binary data to the client encrypted.
 323  */
 324 void client_write_ssl(char *buf, int nbytes)
 325 {
 326         int retval;
 327         int nremain;
 328         char junk[1];
 329
 330         nremain = nbytes;
 331
 332         while (nremain > 0) {
 333                 if (SSL_want_write(CC->ssl)) {
 334                         if ((SSL_read(CC->ssl, junk, 0)) < 1) {
 335                                 lprintf(9, "SSL_read in client_write:\n");
 336                                 ERR_print_errors_fp(stderr);
 337                         }
 338                 }
 339                 retval =
 340                     SSL_write(CC->ssl, &buf[nbytes - nremain], nremain);
 341                 if (retval < 1) {
 342                         long errval;
 343
 344                         errval = SSL_get_error(CC->ssl, retval);
 345                         if (errval == SSL_ERROR_WANT_READ ||
 346                             errval == SSL_ERROR_WANT_WRITE) {
 347                                 sleep(1);
 348                                 continue;
 349                         }
 350                         lprintf(9, "SSL_write got error %ld, ret %d\n", errval, retval);
 351                         if (retval == -1)
 352                                 lprintf(9, "errno is %d\n", errno);
 353                         endtls();
 354                         client_write(&buf[nbytes - nremain], nremain);
 355                         return;
 356                 }
 357                 nremain -= retval;
 358         }
 359 }
 360
 361
 362 /*
 363  * client_read_ssl() - read data from the encrypted layer.
 364  */
 365 int client_read_ssl(char *buf, int bytes, int timeout)
 366 {
 367 #if 0
 368         fd_set rfds;
 369         struct timeval tv;
 370         int retval;
 371         int s;
 372 #endif
 373         int len, rlen;
 374         char junk[1];
 375
 376         len = 0;
 377         while (len < bytes) {
 378 #if 0
 379                 /*
 380                  * This code is disabled because we don't need it when
 381                  * using blocking reads (which we are). -IO
 382                  */
 383                 FD_ZERO(&rfds);
 384                 s = BIO_get_fd(CC->ssl->rbio, NULL);
 385                 FD_SET(s, &rfds);
 386                 tv.tv_sec = timeout;
 387                 tv.tv_usec = 0;
 388
 389                 retval = select(s + 1, &rfds, NULL, NULL, &tv);
 390
 391                 if (FD_ISSET(s, &rfds) == 0) {
 392                         return (0);
 393                 }
 394
 395 #endif
 396                 if (SSL_want_read(CC->ssl)) {
 397                         if ((SSL_write(CC->ssl, junk, 0)) < 1) {
 398                                 lprintf(9, "SSL_write in client_read:\n");
 399                                 ERR_print_errors_fp(stderr);
 400                         }
 401                 }
 402                 rlen = SSL_read(CC->ssl, &buf[len], bytes - len);
 403                 if (rlen < 1) {
 404                         long errval;
 405
 406                         errval = SSL_get_error(CC->ssl, rlen);
 407                         if (errval == SSL_ERROR_WANT_READ ||
 408                             errval == SSL_ERROR_WANT_WRITE) {
 409                                 sleep(1);
 410                                 continue;
 411                         }
 412                         lprintf(9, "SSL_read got error %ld\n", errval);
 413                         endtls();
 414                         return (client_read_to
 415                                 (&buf[len], bytes - len, timeout));
 416                 }
 417                 len += rlen;
 418         }
 419         return (1);
 420 }
 421
 422
 423 /*
 424  * CtdlStartTLS() starts SSL/TLS encryption for the current session.  It
 425  * must be supplied with pre-generated strings for responses of "ok," "no
 426  * support for TLS," and "error" so that we can use this in any protocol.
 427  */
 428 void CtdlStartTLS(char *ok_response, char *nosup_response,
 429                         char *error_response) {
 430
 431         int retval, bits, alg_bits;
 432
 433         if (!ssl_ctx) {
 434                 cprintf("%s", nosup_response);
 435                 return;
 436         }
 437         if (!(CC->ssl = SSL_new(ssl_ctx))) {
 438                 lprintf(2, "SSL_new failed: %s\n",
 439                                 ERR_reason_error_string(ERR_get_error()));
 440                 cprintf("%s", error_response);
 441                 return;
 442         }
 443         if (!(SSL_set_fd(CC->ssl, CC->client_socket))) {
 444                 lprintf(2, "SSL_set_fd failed: %s\n",
 445                         ERR_reason_error_string(ERR_get_error()));
 446                 SSL_free(CC->ssl);
 447                 CC->ssl = NULL;
 448                 cprintf("%s", error_response);
 449                 return;
 450         }
 451         cprintf("%s", ok_response);
 452         retval = SSL_accept(CC->ssl);
 453         if (retval < 1) {
 454                 /*
 455                  * Can't notify the client of an error here; they will
 456                  * discover the problem at the SSL layer and should
 457                  * revert to unencrypted communications.
 458                  */
 459                 long errval;
 460
 461                 errval = SSL_get_error(CC->ssl, retval);
 462                 lprintf(2, "SSL_accept failed: %s\n",
 463                         ERR_reason_error_string(ERR_get_error()));
 464                 SSL_free(CC->ssl);
 465                 CC->ssl = NULL;
 466                 return;
 467         }
 468         BIO_set_close(CC->ssl->rbio, BIO_NOCLOSE);
 469         bits =
 470             SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl),
 471                                 &alg_bits);
 472         lprintf(3, "SSL/TLS using %s on %s (%d of %d bits)\n",
 473                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 474                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 475                 bits, alg_bits);
 476         CC->redirect_ssl = 1;
 477 }
 478
 479
 480 /*
 481  * cmd_stls() starts SSL/TLS encryption for the current session
 482  */
 483 void cmd_stls(char *params)
 484 {
 485         char ok_response[SIZ];
 486         char nosup_response[SIZ];
 487         char error_response[SIZ];
 488
 489         sprintf(ok_response,
 490                 "%d Begin TLS negotiation now\n",
 491                 CIT_OK);
 492         sprintf(nosup_response,
 493                 "%d TLS not supported here\n",
 494                 ERROR + CMD_NOT_SUPPORTED);
 495         sprintf(error_response,
 496                 "%d TLS negotiation error\n",
 497                 ERROR + INTERNAL_ERROR);
 498
 499         CtdlStartTLS(ok_response, nosup_response, error_response);
 500 }
 501
 502
 503 /*
 504  * cmd_gtls() returns status info about the TLS connection
 505  */
 506 void cmd_gtls(char *params)
 507 {
 508         int bits, alg_bits;
 509
 510         if (!CC->ssl || !CC->redirect_ssl) {
 511                 cprintf("%d Session is not encrypted.\n", ERROR);
 512                 return;
 513         }
 514         bits =
 515             SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl),
 516                                 &alg_bits);
 517         cprintf("%d %s|%s|%d|%d\n", CIT_OK,
 518                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 519                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 520                 alg_bits, bits);
 521 }
 522
 523
 524 /*
 525  * endtls() shuts down the TLS connection
 526  *
 527  * WARNING:  This may make your session vulnerable to a known plaintext
 528  * attack in the current implmentation.
 529  */
 530 void endtls(void)
 531 {
 532         lprintf(7, "Ending SSL/TLS\n");
 533
 534         if (!CC->ssl) {
 535                 CC->redirect_ssl = 0;
 536                 return;
 537         }
 538
 539         SSL_shutdown(CC->ssl);
 540         SSL_free(CC->ssl);
 541         CC->ssl = NULL;
 542         CC->redirect_ssl = 0;
 543 }
 544
 545
 546 /*
 547  * ssl_lock() callback for OpenSSL mutex locks
 548  */
 549 void ssl_lock(int mode, int n, const char *file, int line)
 550 {
 551         if (mode & CRYPTO_LOCK)
 552                 pthread_mutex_lock(SSLCritters[n]);
 553         else
 554                 pthread_mutex_unlock(SSLCritters[n]);
 555 }
 556 #endif                          /* HAVE_OPENSSL */