citadel/serv_crypto.c

   1 /* $Id$ */
   2
   3 #include <string.h>
   4 #include <unistd.h>
   5 #include <sys/types.h>
   6 #include "sysdep.h"
   7
   8 #ifdef HAVE_OPENSSL
   9 #include <openssl/ssl.h>
  10 #include <openssl/err.h>
  11 #include <openssl/rand.h>
  12 #endif
  13
  14 #if TIME_WITH_SYS_TIME
  15 # include <sys/time.h>
  16 # include <time.h>
  17 #else
  18 # if HAVE_SYS_TIME_H
  19 #  include <sys/time.h>
  20 # else
  21 #  include <time.h>
  22 # endif
  23 #endif
  24
  25 #ifdef HAVE_PTHREAD_H
  26 #include <pthread.h>
  27 #endif
  28
  29 #ifdef HAVE_SYS_SELECT_H
  30 #include <sys/select.h>
  31 #endif
  32
  33 #include <stdio.h>
  34 #include "server.h"
  35 #include "serv_crypto.h"
  36 #include "sysdep_decls.h"
  37 #include "serv_extensions.h"
  38
  39
  40 #ifdef HAVE_OPENSSL
  41 SSL_CTX *ssl_ctx;               /* SSL context */
  42 pthread_mutex_t **SSLCritters;  /* Things needing locking */
  43
  44 static unsigned long id_callback(void)
  45 {
  46         return (unsigned long) pthread_self();
  47 }
  48
  49  /*
  50   * Set up the cert things on the server side. We do need both the
  51   * private key (in key_file) and the cert (in cert_file).
  52   * Both files may be identical.
  53   *
  54   * This function is taken from OpenSSL apps/s_cb.c
  55   */
  56
  57 static int set_cert_stuff(SSL_CTX * ctx,
  58                           const char *cert_file, const char *key_file)
  59 {
  60         if (cert_file != NULL) {
  61                 if (SSL_CTX_use_certificate_file(ctx, cert_file,
  62                                                  SSL_FILETYPE_PEM) <= 0) {
  63                         lprintf(3, "unable to get certificate from '%s'",
  64                                 cert_file);
  65                         return (0);
  66                 }
  67                 if (key_file == NULL)
  68                         key_file = cert_file;
  69                 if (SSL_CTX_use_PrivateKey_file(ctx, key_file,
  70                                                 SSL_FILETYPE_PEM) <= 0) {
  71                         lprintf(3, "unable to get private key from '%s'",
  72                                 key_file);
  73                         return (0);
  74                 }
  75                 /* Now we know that a key and cert have been set against
  76                  * the SSL context */
  77                 if (!SSL_CTX_check_private_key(ctx)) {
  78                         lprintf(3,
  79                                 "Private key does not match the certificate public key");
  80                         return (0);
  81                 }
  82         }
  83         return (1);
  84 }
  85
  86
  87 void init_ssl(void)
  88 {
  89         SSL_METHOD *ssl_method;
  90         DH *dh;
  91
  92         if (!access("/var/run/egd-pool", F_OK))
  93                 RAND_egd("/var/run/egd-pool");
  94
  95         if (!RAND_status()) {
  96                 lprintf(2,
  97                         "PRNG not adequately seeded, won't do SSL/TLS\n");
  98                 return;
  99         }
 100         SSLCritters =
 101             mallok(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
 102         if (!SSLCritters) {
 103                 lprintf(1, "citserver: can't allocate memory!!\n");
 104                 /* Nothing's been initialized, just die */
 105                 exit(1);
 106         } else {
 107                 int a;
 108
 109                 for (a = 0; a < CRYPTO_num_locks(); a++) {
 110                         SSLCritters[a] = mallok(sizeof(pthread_mutex_t));
 111                         if (!SSLCritters[a]) {
 112                                 lprintf(1,
 113                                         "citserver: can't allocate memory!!\n");
 114                                 /* Nothing's been initialized, just die */
 115                                 exit(1);
 116                         }
 117                         pthread_mutex_init(SSLCritters[a], NULL);
 118                 }
 119         }
 120
 121         /*
 122          * Initialize SSL transport layer
 123          */
 124         SSL_library_init();
 125         SSL_load_error_strings();
 126         ssl_method = SSLv23_server_method();
 127         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
 128                 lprintf(2, "SSL_CTX_new failed: %s\n",
 129                         ERR_reason_error_string(ERR_get_error()));
 130                 return;
 131         }
 132         if (!(SSL_CTX_set_cipher_list(ssl_ctx, CIT_CIPHERS))) {
 133                 lprintf(2, "SSL: No ciphers available\n");
 134                 SSL_CTX_free(ssl_ctx);
 135                 ssl_ctx = NULL;
 136                 return;
 137         }
 138 #if 0
 139 #if SSLEAY_VERSION_NUMBER >= 0x00906000L
 140         SSL_CTX_set_mode(ssl_ctx, SSL_CTX_get_mode(ssl_ctx) |
 141                          SSL_MODE_AUTO_RETRY);
 142 #endif
 143 #endif
 144         SSL_CTX_set_mode(ssl_ctx, SSL_CTX_get_mode(ssl_ctx) |
 145                         SSL_MODE_AUTO_RETRY);
 146
 147         CRYPTO_set_locking_callback(ssl_lock);
 148         CRYPTO_set_id_callback(id_callback);
 149
 150         /* Load DH parameters into the context */
 151         dh = DH_new();
 152         if (!dh) {
 153                 lprintf(2, "init_ssl() can't allocate a DH object: %s\n",
 154                         ERR_reason_error_string(ERR_get_error()));
 155                 SSL_CTX_free(ssl_ctx);
 156                 ssl_ctx = NULL;
 157                 return;
 158         }
 159         if (!(BN_hex2bn(&(dh->p), DH_P))) {
 160                 lprintf(2, "init_ssl() can't assign DH_P: %s\n",
 161                         ERR_reason_error_string(ERR_get_error()));
 162                 SSL_CTX_free(ssl_ctx);
 163                 ssl_ctx = NULL;
 164                 return;
 165         }
 166         if (!(BN_hex2bn(&(dh->g), DH_G))) {
 167                 lprintf(2, "init_ssl() can't assign DH_G: %s\n",
 168                         ERR_reason_error_string(ERR_get_error()));
 169                 SSL_CTX_free(ssl_ctx);
 170                 ssl_ctx = NULL;
 171                 return;
 172         }
 173         dh->length = DH_L;
 174         SSL_CTX_set_tmp_dh(ssl_ctx, dh);
 175         DH_free(dh);
 176
 177         /* Get our certificates in order */
 178         if (set_cert_stuff(ssl_ctx,
 179                            BBSDIR "/keys/citadel.cer",
 180                            BBSDIR "/keys/citadel.key") != 1) {
 181
 182                 lprintf(3, "SSL ERROR: cert is bad!\n");
 183
 184         }
 185
 186         /* Finally let the server know we're here */
 187         CtdlRegisterProtoHook(cmd_stls, "STLS", "Start SSL/TLS session");
 188         CtdlRegisterProtoHook(cmd_gtls, "GTLS",
 189                               "Get SSL/TLS session status");
 190         CtdlRegisterSessionHook(endtls, EVT_STOP);
 191 }
 192
 193
 194 /*
 195  * client_write_ssl() Send binary data to the client encrypted.
 196  */
 197 void client_write_ssl(char *buf, int nbytes)
 198 {
 199         int retval;
 200         int nremain;
 201         char junk[1];
 202
 203         nremain = nbytes;
 204
 205         while (nremain > 0) {
 206                 if (SSL_want_write(CC->ssl)) {
 207                         if ((SSL_read(CC->ssl, junk, 0)) < 1) {
 208                                 lprintf(9, "SSL_read in client_write:\n");
 209                                 ERR_print_errors_fp(stderr);
 210                         }
 211                 }
 212                 retval =
 213                     SSL_write(CC->ssl, &buf[nbytes - nremain], nremain);
 214                 if (retval < 1) {
 215                         long errval;
 216
 217                         errval = SSL_get_error(CC->ssl, retval);
 218                         if (errval == SSL_ERROR_WANT_READ ||
 219                             errval == SSL_ERROR_WANT_WRITE) {
 220                                 sleep(1);
 221                                 continue;
 222                         }
 223                         lprintf(9, "SSL_write got error %ld, ret %d\n", errval, retval);
 224                         if (retval == -1)
 225                                 lprintf(9, "errno is %d\n", errno);
 226                         endtls();
 227                         client_write(&buf[nbytes - nremain], nremain);
 228                         return;
 229                 }
 230                 nremain -= retval;
 231         }
 232 }
 233
 234
 235 /*
 236  * client_read_ssl() - read data from the encrypted layer.
 237  */
 238 int client_read_ssl(char *buf, int bytes, int timeout)
 239 {
 240 #if 0
 241         fd_set rfds;
 242         struct timeval tv;
 243         int retval;
 244         int s;
 245 #endif
 246         int len, rlen;
 247         char junk[1];
 248
 249         len = 0;
 250         while (len < bytes) {
 251 #if 0
 252                 /*
 253                  * This code is disabled because we don't need it when
 254                  * using blocking reads (which we are). -IO
 255                  */
 256                 FD_ZERO(&rfds);
 257                 s = BIO_get_fd(CC->ssl->rbio, NULL);
 258                 FD_SET(s, &rfds);
 259                 tv.tv_sec = timeout;
 260                 tv.tv_usec = 0;
 261
 262                 retval = select(s + 1, &rfds, NULL, NULL, &tv);
 263
 264                 if (FD_ISSET(s, &rfds) == 0) {
 265                         return (0);
 266                 }
 267
 268 #endif
 269                 if (SSL_want_read(CC->ssl)) {
 270                         if ((SSL_write(CC->ssl, junk, 0)) < 1) {
 271                                 lprintf(9, "SSL_write in client_read:\n");
 272                                 ERR_print_errors_fp(stderr);
 273                         }
 274                 }
 275                 rlen = SSL_read(CC->ssl, &buf[len], bytes - len);
 276                 if (rlen < 1) {
 277                         long errval;
 278
 279                         errval = SSL_get_error(CC->ssl, rlen);
 280                         if (errval == SSL_ERROR_WANT_READ ||
 281                             errval == SSL_ERROR_WANT_WRITE) {
 282                                 sleep(1);
 283                                 continue;
 284                         }
 285                         lprintf(9, "SSL_read got error %ld\n", errval);
 286                         endtls();
 287                         return (client_read_to
 288                                 (&buf[len], bytes - len, timeout));
 289                 }
 290                 len += rlen;
 291         }
 292         return (1);
 293 }
 294
 295
 296 /*
 297  * cmd_stls() starts SSL/TLS encryption for the current session
 298  */
 299 void cmd_stls(char *params)
 300 {
 301         int retval, bits, alg_bits;
 302
 303         if (!ssl_ctx) {
 304                 cprintf("%d No SSL_CTX available\n", ERROR + CMD_NOT_SUPPORTED);
 305                 return;
 306         }
 307         if (!(CC->ssl = SSL_new(ssl_ctx))) {
 308                 lprintf(2, "SSL_new failed: %s\n",
 309                                 ERR_reason_error_string(ERR_peek_error()));
 310                 cprintf("%d SSL_new: %s\n", ERROR + INTERNAL_ERROR,
 311                                 ERR_reason_error_string(ERR_get_error()));
 312                 return;
 313         }
 314         if (!(SSL_set_fd(CC->ssl, CC->client_socket))) {
 315                 lprintf(2, "SSL_set_fd failed: %s\n",
 316                         ERR_reason_error_string(ERR_peek_error()));
 317                 SSL_free(CC->ssl);
 318                 CC->ssl = NULL;
 319                 cprintf("%d SSL_set_fd: %s\n", ERROR + INTERNAL_ERROR,
 320                                 ERR_reason_error_string(ERR_get_error()));
 321                 return;
 322         }
 323         cprintf("%d \n", CIT_OK);
 324         retval = SSL_accept(CC->ssl);
 325         if (retval < 1) {
 326                 /*
 327                  * Can't notify the client of an error here; they will
 328                  * discover the problem at the SSL layer and should
 329                  * revert to unencrypted communications.
 330                  */
 331                 long errval;
 332
 333                 errval = SSL_get_error(CC->ssl, retval);
 334                 lprintf(2, "SSL_accept failed: %s\n",
 335                         ERR_reason_error_string(ERR_get_error()));
 336                 SSL_free(CC->ssl);
 337                 CC->ssl = NULL;
 338                 return;
 339         }
 340         BIO_set_close(CC->ssl->rbio, BIO_NOCLOSE);
 341         bits =
 342             SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl),
 343                                 &alg_bits);
 344         lprintf(3, "SSL/TLS using %s on %s (%d of %d bits)\n",
 345                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 346                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 347                 bits, alg_bits);
 348         CC->redirect_ssl = 1;
 349 }
 350
 351
 352 /*
 353  * cmd_gtls() returns status info about the TLS connection
 354  */
 355 void cmd_gtls(char *params)
 356 {
 357         int bits, alg_bits;
 358
 359         if (!CC->ssl || !CC->redirect_ssl) {
 360                 cprintf("%d Session is not encrypted.\n", ERROR);
 361                 return;
 362         }
 363         bits =
 364             SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl),
 365                                 &alg_bits);
 366         cprintf("%d %s|%s|%d|%d\n", CIT_OK,
 367                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 368                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 369                 alg_bits, bits);
 370 }
 371
 372
 373 /*
 374  * endtls() shuts down the TLS connection
 375  *
 376  * WARNING:  This may make your session vulnerable to a known plaintext
 377  * attack in the current implmentation.
 378  */
 379 void endtls(void)
 380 {
 381         lprintf(7, "Ending SSL/TLS\n");
 382
 383         if (!CC->ssl) {
 384                 CC->redirect_ssl = 0;
 385                 return;
 386         }
 387
 388         SSL_shutdown(CC->ssl);
 389         SSL_free(CC->ssl);
 390         CC->ssl = NULL;
 391         CC->redirect_ssl = 0;
 392 }
 393
 394
 395 /*
 396  * ssl_lock() callback for OpenSSL mutex locks
 397  */
 398 void ssl_lock(int mode, int n, const char *file, int line)
 399 {
 400         if (mode & CRYPTO_LOCK)
 401                 pthread_mutex_lock(SSLCritters[n]);
 402         else
 403                 pthread_mutex_unlock(SSLCritters[n]);
 404 }
 405 #endif                          /* HAVE_OPENSSL */