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 "dynloader.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         return pthread_self();
  46 }
  47
  48 void init_ssl(void)
  49 {
  50         SSL_METHOD *ssl_method;
  51         DH *dh;
  52
  53         if (!access("/var/run/egd-pool", F_OK))
  54                 RAND_egd("/var/run/egd-pool");
  55
  56         if (!RAND_status()) {
  57                 lprintf(2, "PRNG not adequately seeded, won't do SSL/TLS\n");
  58                 return;
  59         }
  60         SSLCritters = mallok(CRYPTO_num_locks() * sizeof (pthread_mutex_t *));
  61         if (!SSLCritters) {
  62                 lprintf(1, "citserver: can't allocate memory!!\n");
  63                 /* Nothing's been initialized, just die */
  64                 exit(1);
  65         } else {
  66                 int a;
  67
  68                 for (a=0; a<CRYPTO_num_locks(); a++) {
  69                         SSLCritters[a] = mallok(sizeof (pthread_mutex_t));
  70                         if (!SSLCritters[a]) {
  71                                 lprintf(1, "citserver: can't allocate memory!!\n");
  72                                 /* Nothing's been initialized, just die */
  73                                 exit(1);
  74                         }
  75                         pthread_mutex_init(SSLCritters[a], NULL);
  76                 }
  77         }
  78
  79         /*
  80          * Initialize SSL transport layer
  81          */
  82         SSL_library_init();
  83         SSL_load_error_strings();
  84         ssl_method = SSLv23_server_method();
  85         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
  86                 lprintf(2, "SSL_CTX_new failed: %s\n",
  87                                 ERR_reason_error_string(ERR_get_error()));
  88                 return;
  89         }
  90         if (!(SSL_CTX_set_cipher_list(ssl_ctx, CIT_CIPHERS))) {
  91                 lprintf(2, "SSL: No ciphers available\n");
  92                 SSL_CTX_free(ssl_ctx);
  93                 ssl_ctx = NULL;
  94                 return;
  95         }
  96 #if 0
  97 #if SSLEAY_VERSION_NUMBER >= 0x00906000L
  98         SSL_CTX_set_mode(ssl_ctx, SSL_CTX_get_mode(ssl_ctx) |
  99                         SSL_MODE_AUTO_RETRY);
 100 #endif
 101 #endif
 102         CRYPTO_set_locking_callback(ssl_lock);
 103         CRYPTO_set_id_callback(id_callback);
 104
 105         /* Load DH parameters into the context */
 106         dh = DH_new();
 107         if (!dh) {
 108                 lprintf(2, "init_ssl() can't allocate a DH object: %s\n",
 109                                 ERR_reason_error_string(ERR_get_error()));
 110                 SSL_CTX_free(ssl_ctx);
 111                 ssl_ctx = NULL;
 112                 return;
 113         }
 114         if (!(BN_hex2bn(&(dh->p), DH_P))) {
 115                 lprintf(2, "init_ssl() can't assign DH_P: %s\n",
 116                                 ERR_reason_error_string(ERR_get_error()));
 117                 SSL_CTX_free(ssl_ctx);
 118                 ssl_ctx = NULL;
 119                 return;
 120         }
 121         if (!(BN_hex2bn(&(dh->g), DH_G))) {
 122                 lprintf(2, "init_ssl() can't assign DH_G: %s\n",
 123                                 ERR_reason_error_string(ERR_get_error()));
 124                 SSL_CTX_free(ssl_ctx);
 125                 ssl_ctx = NULL;
 126                 return;
 127         }
 128         dh->length = DH_L;
 129         SSL_CTX_set_tmp_dh(ssl_ctx, dh);
 130         DH_free(dh);
 131
 132         /* Finally let the server know we're here */
 133         CtdlRegisterProtoHook(cmd_stls, "STLS", "Start SSL/TLS session");
 134         CtdlRegisterProtoHook(cmd_gtls, "GTLS", "Get SSL/TLS session status");
 135         CtdlRegisterSessionHook(endtls, EVT_STOP);
 136 }
 137
 138
 139 /*
 140  * client_write_ssl() Send binary data to the client encrypted.
 141  */
 142 void client_write_ssl(char *buf, int nbytes)
 143 {
 144         int retval;
 145         int nremain;
 146         char junk[1];
 147
 148         nremain = nbytes;
 149
 150         while (nremain > 0) {
 151                 if (SSL_want_write(CC->ssl)) {
 152                         if ((SSL_read(CC->ssl, junk, 0)) < 1) {
 153                                 lprintf(9, "SSL_read in client_write:\n");
 154                                 ERR_print_errors_fp(stderr);
 155                         }
 156                 }
 157                 retval = SSL_write(CC->ssl, &buf[nbytes - nremain], nremain);
 158                 if (retval < 1) {
 159                         long errval;
 160
 161                         errval = SSL_get_error(CC->ssl, retval);
 162                         if (errval == SSL_ERROR_WANT_READ ||
 163                                         errval == SSL_ERROR_WANT_WRITE) {
 164                                 sleep(1);
 165                                 continue;
 166                         }
 167                         lprintf(9, "SSL_write got error %ld\n", errval);
 168                         endtls();
 169                         client_write(&buf[nbytes - nremain], nremain);
 170                         return;
 171                 }
 172                 nremain -= retval;
 173         }
 174 }
 175
 176
 177 /*
 178  * client_read_ssl() - read data from the encrypted layer.
 179  */
 180 int client_read_ssl(char *buf, int bytes, int timeout)
 181 {
 182         int len,rlen;
 183         fd_set rfds;
 184         struct timeval tv;
 185         int retval;
 186         int s;
 187         char junk[1];
 188
 189         len = 0;
 190         while(len<bytes) {
 191                 FD_ZERO(&rfds);
 192                 s = BIO_get_fd(CC->ssl->rbio, NULL);
 193                 FD_SET(s, &rfds);
 194                 tv.tv_sec = timeout;
 195                 tv.tv_usec = 0;
 196
 197                 retval = select(s+1, &rfds, NULL, NULL, &tv);
 198
 199                 if (FD_ISSET(s, &rfds) == 0) {
 200                         return(0);
 201                 }
 202
 203                 if (SSL_want_read(CC->ssl)) {
 204                         if ((SSL_write(CC->ssl, junk, 0)) < 1) {
 205                                 lprintf(9, "SSL_write in client_read:\n");
 206                                 ERR_print_errors_fp(stderr);
 207                         }
 208                 }
 209                 rlen = SSL_read(CC->ssl, &buf[len], bytes-len);
 210                 if (rlen<1) {
 211                         long errval;
 212
 213                         errval = SSL_get_error(CC->ssl, rlen);
 214                         if (errval == SSL_ERROR_WANT_READ ||
 215                                         errval == SSL_ERROR_WANT_WRITE) {
 216                                 sleep(1);
 217                                 continue;
 218                         }
 219                         lprintf(9, "SSL_read got error %ld\n", errval);
 220                         endtls();
 221                         return (client_read_to(&buf[len], bytes - len, timeout));
 222                 }
 223                 len += rlen;
 224         }
 225         return(1);
 226 }
 227
 228
 229 /*
 230  * cmd_stls() starts SSL/TLS encryption for the current session
 231  */
 232 void cmd_stls(char *params)
 233 {
 234         int retval, bits, alg_bits;
 235
 236         if (!ssl_ctx) {
 237                 cprintf("%d No SSL_CTX available\n", ERROR);
 238                 return;
 239         }
 240         if (!(CC->ssl = SSL_new(ssl_ctx))) {
 241                 lprintf(2, "SSL_new failed: %s\n",
 242                                 ERR_reason_error_string(ERR_peek_error()));
 243                 cprintf("%d SSL_new: %s\n", ERROR,
 244                                 ERR_reason_error_string(ERR_get_error()));
 245                 return;
 246         }
 247         if (!(SSL_set_fd(CC->ssl, CC->client_socket))) {
 248                 lprintf(2, "SSL_set_fd failed: %s\n",
 249                                 ERR_reason_error_string(ERR_peek_error()));
 250                 SSL_free(CC->ssl);
 251                 CC->ssl = NULL;
 252                 cprintf("%d SSL_set_fd: %s\n", ERROR,
 253                                 ERR_reason_error_string(ERR_get_error()));
 254                 return;
 255         }
 256         cprintf("%d \n", CIT_OK);
 257         retval = SSL_accept(CC->ssl);
 258         if (retval < 1) {
 259                 /*
 260                  * Can't notify the client of an error here; they will
 261                  * discover the problem at the SSL layer and should
 262                  * revert to unencrypted communications.
 263                  */
 264                 long errval;
 265
 266                 errval = SSL_get_error(CC->ssl, retval);
 267                 lprintf(2, "SSL_accept failed: %s\n",
 268                                 ERR_reason_error_string(ERR_get_error()));
 269                 SSL_free(CC->ssl);
 270                 CC->ssl = NULL;
 271                 return;
 272         }
 273         BIO_set_close(CC->ssl->rbio, BIO_NOCLOSE);
 274         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl), &alg_bits);
 275         lprintf(3, "SSL/TLS using %s on %s (%d of %d bits)\n",
 276                         SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 277                         SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 278                         bits, alg_bits);
 279         CC->redirect_ssl = 1;
 280 }
 281
 282
 283 /*
 284  * cmd_gtls() returns status info about the TLS connection
 285  */
 286 void cmd_gtls(char *params)
 287 {
 288         int bits, alg_bits;
 289
 290         if (!CC->ssl || !CC->redirect_ssl) {
 291                 cprintf("%d Session is not encrypted.\n", ERROR);
 292                 return;
 293         }
 294         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl), &alg_bits);
 295         cprintf("%d %s|%s|%d|%d\n", CIT_OK,
 296                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 297                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 298                 alg_bits, bits);
 299 }
 300
 301
 302 /*
 303  * endtls() shuts down the TLS connection
 304  *
 305  * WARNING:  This may make your session vulnerable to a known plaintext
 306  * attack in the current implmentation.
 307  */
 308 void endtls(void)
 309 {
 310         lprintf(7, "Ending SSL/TLS\n");
 311
 312         if (!CC->ssl) {
 313                 CC->redirect_ssl = 0;
 314                 return;
 315         }
 316
 317         SSL_shutdown(CC->ssl);
 318         SSL_free(CC->ssl);
 319         CC->ssl = NULL;
 320         CC->redirect_ssl = 0;
 321 }
 322
 323
 324 /*
 325  * ssl_lock() callback for OpenSSL mutex locks
 326  */
 327 void ssl_lock(int mode, int n, const char *file, int line)
 328 {
 329         if (mode & CRYPTO_LOCK)
 330                 pthread_mutex_lock(SSLCritters[n]);
 331         else
 332                 pthread_mutex_unlock(SSLCritters[n]);
 333 }
 334 #endif /* HAVE_OPENSSL */