citadel/serv_crypto.c

   1 /* $Id$ */
   2
   3 #include <unistd.h>
   4 #include <sys/types.h>
   5 #include "sysdep.h"
   6
   7 #ifdef HAVE_OPENSSL
   8 #include <openssl/ssl.h>
   9 #include <openssl/err.h>
  10 #include <openssl/rand.h>
  11 #endif
  12
  13 #if TIME_WITH_SYS_TIME
  14 # include <sys/time.h>
  15 # include <time.h>
  16 #else
  17 # if HAVE_SYS_TIME_H
  18 #  include <sys/time.h>
  19 # else
  20 #  include <time.h>
  21 # endif
  22 #endif
  23
  24 #ifdef HAVE_PTHREAD_H
  25 #include <pthread.h>
  26 #endif
  27
  28 #ifdef HAVE_SYS_SELECT_H
  29 #include <sys/select.h>
  30 #endif
  31
  32 #include <stdio.h>
  33 #include "server.h"
  34 #include "serv_crypto.h"
  35 #include "sysdep_decls.h"
  36 #include "dynloader.h"
  37
  38
  39 #ifdef HAVE_OPENSSL
  40 SSL_CTX *ssl_ctx;                               /* SSL context */
  41 pthread_mutex_t **SSLCritters;                  /* Things needing locking */
  42
  43
  44 void init_ssl(void)
  45 {
  46         SSL_METHOD *ssl_method;
  47         DH *dh;
  48
  49         if (!RAND_status()) {
  50                 lprintf(2, "PRNG not adequately seeded, won't do SSL/TLS\n");
  51                 return;
  52         }
  53         SSLCritters = mallok(CRYPTO_num_locks() * sizeof (pthread_mutex_t *));
  54         if (!SSLCritters) {
  55                 lprintf(1, "citserver: can't allocate memory!!\n");
  56                 /* Nothing's been initialized, just die */
  57                 exit(1);
  58         } else {
  59                 int a;
  60
  61                 for (a=0; a<CRYPTO_num_locks(); a++) {
  62                         SSLCritters[a] = mallok(sizeof (pthread_mutex_t));
  63                         if (!SSLCritters[a]) {
  64                                 lprintf(1, "citserver: can't allocate memory!!\n");
  65                                 /* Nothing's been initialized, just die */
  66                                 exit(1);
  67                         }
  68                         pthread_mutex_init(SSLCritters[a], NULL);
  69                 }
  70         }
  71
  72         /*
  73          * Initialize SSL transport layer
  74          */
  75         SSL_library_init();
  76         SSL_load_error_strings();
  77         ssl_method = SSLv23_server_method();
  78         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
  79                 lprintf(2, "SSL_CTX_new failed: %s\n",
  80                                 ERR_reason_error_string(ERR_get_error()));
  81                 return;
  82         }
  83         if (!(SSL_CTX_set_cipher_list(ssl_ctx, CIT_CIPHERS))) {
  84                 lprintf(2, "SSL: No ciphers available\n");
  85                 SSL_CTX_free(ssl_ctx);
  86                 ssl_ctx = NULL;
  87                 return;
  88         }
  89 #if 0
  90 #if SSLEAY_VERSION_NUMBER >= 0x00906000L
  91         SSL_CTX_set_mode(ssl_ctx, SSL_CTX_get_mode(ssl_ctx) |
  92                         SSL_MODE_AUTO_RETRY);
  93 #endif
  94 #endif
  95         CRYPTO_set_locking_callback(ssl_lock);
  96         CRYPTO_set_id_callback(pthread_self);
  97
  98         /* Load DH parameters into the context */
  99         dh = DH_new();
 100         if (!dh) {
 101                 lprintf(2, "init_ssl() can't allocate a DH object: %s\n",
 102                                 ERR_reason_error_string(ERR_get_error()));
 103                 SSL_CTX_free(ssl_ctx);
 104                 ssl_ctx = NULL;
 105                 return;
 106         }
 107         if (!(BN_hex2bn(&(dh->p), DH_P))) {
 108                 lprintf(2, "init_ssl() can't assign DH_P: %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->g), DH_G))) {
 115                 lprintf(2, "init_ssl() can't assign DH_G: %s\n",
 116                                 ERR_reason_error_string(ERR_get_error()));
 117                 SSL_CTX_free(ssl_ctx);
 118                 ssl_ctx = NULL;
 119                 return;
 120         }
 121         dh->length = DH_L;
 122         SSL_CTX_set_tmp_dh(ssl_ctx, dh);
 123         DH_free(dh);
 124
 125         /* Finally let the server know we're here */
 126         CtdlRegisterProtoHook(cmd_stls, "STLS", "Start SSL/TLS session");
 127         CtdlRegisterProtoHook(cmd_gtls, "GTLS", "Get SSL/TLS session status");
 128         CtdlRegisterSessionHook(endtls, EVT_STOP);
 129 }
 130
 131
 132 /*
 133  * client_write_ssl() Send binary data to the client encrypted.
 134  */
 135 void client_write_ssl(char *buf, int nbytes)
 136 {
 137         int retval;
 138         int nremain;
 139         char junk[1];
 140
 141         nremain = nbytes;
 142
 143         while (nremain > 0) {
 144                 if (SSL_want_write(CC->ssl)) {
 145                         if ((SSL_read(CC->ssl, junk, 0)) < 1) {
 146                                 lprintf(9, "SSL_read in client_write:\n");
 147                                 ERR_print_errors_fp(stderr);
 148                         }
 149                 }
 150                 retval = SSL_write(CC->ssl, &buf[nbytes - nremain], nremain);
 151                 if (retval < 1) {
 152                         long errval;
 153
 154                         errval = SSL_get_error(CC->ssl, retval);
 155                         if (errval == SSL_ERROR_WANT_READ ||
 156                                         errval == SSL_ERROR_WANT_WRITE) {
 157                                 sleep(1);
 158                                 continue;
 159                         }
 160                         lprintf(9, "SSL_write got error %ld\n", errval);
 161                         endtls();
 162                         client_write(&buf[nbytes - nremain], nremain);
 163                         return;
 164                 }
 165                 nremain -= retval;
 166         }
 167 }
 168
 169
 170 /*
 171  * client_read_ssl() - read data from the encrypted layer.
 172  */
 173 int client_read_ssl(char *buf, int bytes, int timeout)
 174 {
 175         int len,rlen;
 176         fd_set rfds;
 177         struct timeval tv;
 178         int retval;
 179         int s;
 180         char junk[1];
 181
 182         len = 0;
 183         while(len<bytes) {
 184                 FD_ZERO(&rfds);
 185                 s = BIO_get_fd(CC->ssl->rbio, NULL);
 186                 FD_SET(s, &rfds);
 187                 tv.tv_sec = timeout;
 188                 tv.tv_usec = 0;
 189
 190                 retval = select(s+1, &rfds, NULL, NULL, &tv);
 191
 192                 if (FD_ISSET(s, &rfds) == 0) {
 193                         return(0);
 194                 }
 195
 196                 if (SSL_want_read(CC->ssl)) {
 197                         if ((SSL_write(CC->ssl, junk, 0)) < 1) {
 198                                 lprintf(9, "SSL_write in client_read:\n");
 199                                 ERR_print_errors_fp(stderr);
 200                         }
 201                 }
 202                 rlen = SSL_read(CC->ssl, &buf[len], bytes-len);
 203                 if (rlen<1) {
 204                         long errval;
 205
 206                         errval = SSL_get_error(CC->ssl, rlen);
 207                         if (errval == SSL_ERROR_WANT_READ ||
 208                                         errval == SSL_ERROR_WANT_WRITE) {
 209                                 sleep(1);
 210                                 continue;
 211                         }
 212                         lprintf(9, "SSL_read got error %ld\n", errval);
 213                         endtls();
 214                         return (client_read_to(&buf[len], bytes - len, timeout));
 215                 }
 216                 len += rlen;
 217         }
 218         return(1);
 219 }
 220
 221
 222 /*
 223  * cmd_stls() starts SSL/TLS encryption for the current session
 224  */
 225 void cmd_stls(char *params)
 226 {
 227         int retval, bits, alg_bits;
 228
 229         if (!ssl_ctx) {
 230                 cprintf("%d No SSL_CTX available\n", ERROR);
 231                 return;
 232         }
 233         if (!(CC->ssl = SSL_new(ssl_ctx))) {
 234                 lprintf(2, "SSL_new failed: %s\n",
 235                                 ERR_reason_error_string(ERR_peek_error()));
 236                 cprintf("%d SSL_new: %s\n", ERROR,
 237                                 ERR_reason_error_string(ERR_get_error()));
 238                 return;
 239         }
 240         if (!(SSL_set_fd(CC->ssl, CC->client_socket))) {
 241                 lprintf(2, "SSL_set_fd failed: %s\n",
 242                                 ERR_reason_error_string(ERR_peek_error()));
 243                 SSL_free(CC->ssl);
 244                 CC->ssl = NULL;
 245                 cprintf("%d SSL_set_fd: %s\n", ERROR,
 246                                 ERR_reason_error_string(ERR_get_error()));
 247                 return;
 248         }
 249         cprintf("%d \n", OK);
 250         retval = SSL_accept(CC->ssl);
 251         if (retval < 1) {
 252                 /*
 253                  * Can't notify the client of an error here; they will
 254                  * discover the problem at the SSL layer and should
 255                  * revert to unencrypted communications.
 256                  */
 257                 long errval;
 258
 259                 errval = SSL_get_error(CC->ssl, retval);
 260                 lprintf(2, "SSL_accept failed: %s\n",
 261                                 ERR_reason_error_string(ERR_get_error()));
 262                 SSL_free(CC->ssl);
 263                 CC->ssl = NULL;
 264                 return;
 265         }
 266         BIO_set_close(CC->ssl->rbio, BIO_NOCLOSE);
 267         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl), &alg_bits);
 268         lprintf(3, "SSL/TLS using %s on %s (%d of %d bits)\n",
 269                         SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 270                         SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 271                         bits, alg_bits);
 272         CC->redirect_ssl = 1;
 273 }
 274
 275
 276 /*
 277  * cmd_gtls() returns status info about the TLS connection
 278  */
 279 void cmd_gtls(char *params)
 280 {
 281         int bits, alg_bits;
 282
 283         if (!CC->ssl || !CC->redirect_ssl) {
 284                 cprintf("%d Session is not encrypted.\n", ERROR);
 285                 return;
 286         }
 287         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(CC->ssl), &alg_bits);
 288         cprintf("%d %s|%s|%d|%d\n", OK,
 289                 SSL_CIPHER_get_version(SSL_get_current_cipher(CC->ssl)),
 290                 SSL_CIPHER_get_name(SSL_get_current_cipher(CC->ssl)),
 291                 alg_bits, bits);
 292 }
 293
 294
 295 /*
 296  * endtls() shuts down the TLS connection
 297  *
 298  * WARNING:  This may make your session vulnerable to a known plaintext
 299  * attack in the current implmentation.
 300  */
 301 void endtls(void)
 302 {
 303         lprintf(7, "Ending SSL/TLS%s\n");
 304
 305         if (!CC->ssl) {
 306                 CC->redirect_ssl = 0;
 307                 return;
 308         }
 309
 310         SSL_shutdown(CC->ssl);
 311         SSL_free(CC->ssl);
 312         CC->ssl = NULL;
 313         CC->redirect_ssl = 0;
 314 }
 315
 316
 317 /*
 318  * ssl_lock() callback for OpenSSL mutex locks
 319  */
 320 void ssl_lock(int mode, int n, const char *file, int line)
 321 {
 322         if (mode & CRYPTO_LOCK)
 323                 pthread_mutex_lock(SSLCritters[n]);
 324         else
 325                 pthread_mutex_unlock(SSLCritters[n]);
 326 }
 327 #endif /* HAVE_OPENSSL */