roaming_client.c

   1 /* $OpenBSD: roaming_client.c,v 1.3 2010/01/18 01:50:27 dtucker Exp $ */
   2 /*
   3  * Copyright (c) 2004-2009 AppGate Network Security AB
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 #include "includes.h"
  19
  20 #include "openbsd-compat/sys-queue.h"
  21 #include <sys/types.h>
  22 #include <sys/socket.h>
  23
  24 #ifdef HAVE_INTTYPES_H
  25 #include <inttypes.h>
  26 #endif
  27 #include <signal.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30
  31 #include <openssl/crypto.h>
  32 #include <openssl/sha.h>
  33
  34 #include "xmalloc.h"
  35 #include "buffer.h"
  36 #include "channels.h"
  37 #include "cipher.h"
  38 #include "dispatch.h"
  39 #include "clientloop.h"
  40 #include "log.h"
  41 #include "match.h"
  42 #include "misc.h"
  43 #include "packet.h"
  44 #include "ssh.h"
  45 #include "key.h"
  46 #include "kex.h"
  47 #include "readconf.h"
  48 #include "roaming.h"
  49 #include "ssh2.h"
  50 #include "sshconnect.h"
  51
  52 /* import */
  53 extern Options options;
  54 extern char *host;
  55 extern struct sockaddr_storage hostaddr;
  56 extern int session_resumed;
  57
  58 static u_int32_t roaming_id;
  59 static u_int64_t cookie;
  60 static u_int64_t lastseenchall;
  61 static u_int64_t key1, key2, oldkey1, oldkey2;
  62
  63 void
  64 roaming_reply(int type, u_int32_t seq, void *ctxt)
  65 {
  66         if (type == SSH2_MSG_REQUEST_FAILURE) {
  67                 logit("Server denied roaming");
  68                 return;
  69         }
  70         verbose("Roaming enabled");
  71         roaming_id = packet_get_int();
  72         cookie = packet_get_int64();
  73         key1 = oldkey1 = packet_get_int64();
  74         key2 = oldkey2 = packet_get_int64();
  75         set_out_buffer_size(packet_get_int() +  get_snd_buf_size());
  76         roaming_enabled = 1;
  77 }
  78
  79 void
  80 request_roaming(void)
  81 {
  82         packet_start(SSH2_MSG_GLOBAL_REQUEST);
  83         packet_put_cstring(ROAMING_REQUEST);
  84         packet_put_char(1);
  85         packet_put_int(get_recv_buf_size());
  86         packet_send();
  87         client_register_global_confirm(roaming_reply, NULL);
  88 }
  89
  90 static void
  91 roaming_auth_required(void)
  92 {
  93         u_char digest[SHA_DIGEST_LENGTH];
  94         EVP_MD_CTX md;
  95         Buffer b;
  96         const EVP_MD *evp_md = EVP_sha1();
  97         u_int64_t chall, oldchall;
  98
  99         chall = packet_get_int64();
 100         oldchall = packet_get_int64();
 101         if (oldchall != lastseenchall) {
 102                 key1 = oldkey1;
 103                 key2 = oldkey2;
 104         }
 105         lastseenchall = chall;
 106
 107         buffer_init(&b);
 108         buffer_put_int64(&b, cookie);
 109         buffer_put_int64(&b, chall);
 110         EVP_DigestInit(&md, evp_md);
 111         EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
 112         EVP_DigestFinal(&md, digest, NULL);
 113         buffer_free(&b);
 114
 115         packet_start(SSH2_MSG_KEX_ROAMING_AUTH);
 116         packet_put_int64(key1 ^ get_recv_bytes());
 117         packet_put_raw(digest, sizeof(digest));
 118         packet_send();
 119
 120         oldkey1 = key1;
 121         oldkey2 = key2;
 122         calculate_new_key(&key1, cookie, chall);
 123         calculate_new_key(&key2, cookie, chall);
 124
 125         debug("Received %llu bytes", (unsigned long long)get_recv_bytes());
 126         debug("Sent roaming_auth packet");
 127 }
 128
 129 int
 130 resume_kex(void)
 131 {
 132         /*
 133          * This should not happen - if the client sends the kex method
 134          * resume@appgate.com then the kex is done in roaming_resume().
 135          */
 136         return 1;
 137 }
 138
 139 static int
 140 roaming_resume(void)
 141 {
 142         u_int64_t recv_bytes;
 143         char *str = NULL, *kexlist = NULL, *c;
 144         int i, type;
 145         int timeout_ms = options.connection_timeout * 1000;
 146         u_int len;
 147         u_int32_t rnd = 0;
 148
 149         resume_in_progress = 1;
 150
 151         /* Exchange banners */
 152         ssh_exchange_identification(timeout_ms);
 153         packet_set_nonblocking();
 154
 155         /* Send a kexinit message with resume@appgate.com as only kex algo */
 156         packet_start(SSH2_MSG_KEXINIT);
 157         for (i = 0; i < KEX_COOKIE_LEN; i++) {
 158                 if (i % 4 == 0)
 159                         rnd = arc4random();
 160                 packet_put_char(rnd & 0xff);
 161                 rnd >>= 8;
 162         }
 163         packet_put_cstring(KEX_RESUME);
 164         for (i = 1; i < PROPOSAL_MAX; i++) {
 165                 /* kex algorithm added so start with i=1 and not 0 */
 166                 packet_put_cstring(""); /* Not used when we resume */
 167         }
 168         packet_put_char(1); /* first kex_packet follows */
 169         packet_put_int(0); /* reserved */
 170         packet_send();
 171
 172         /* Assume that resume@appgate.com will be accepted */
 173         packet_start(SSH2_MSG_KEX_ROAMING_RESUME);
 174         packet_put_int(roaming_id);
 175         packet_send();
 176
 177         /* Read the server's kexinit and check for resume@appgate.com */
 178         if ((type = packet_read()) != SSH2_MSG_KEXINIT) {
 179                 debug("expected kexinit on resume, got %d", type);
 180                 goto fail;
 181         }
 182         for (i = 0; i < KEX_COOKIE_LEN; i++)
 183                 (void)packet_get_char();
 184         kexlist = packet_get_string(&len);
 185         if (!kexlist
 186             || (str = match_list(KEX_RESUME, kexlist, NULL)) == NULL) {
 187                 debug("server doesn't allow resume");
 188                 goto fail;
 189         }
 190         xfree(str);
 191         for (i = 1; i < PROPOSAL_MAX; i++) {
 192                 /* kex algorithm taken care of so start with i=1 and not 0 */
 193                 xfree(packet_get_string(&len));
 194         }
 195         i = packet_get_char(); /* first_kex_packet_follows */
 196         if (i && (c = strchr(kexlist, ',')))
 197                 *c = 0;
 198         if (i && strcmp(kexlist, KEX_RESUME)) {
 199                 debug("server's kex guess (%s) was wrong, skipping", kexlist);
 200                 (void)packet_read(); /* Wrong guess - discard packet */
 201         }
 202
 203         /*
 204          * Read the ROAMING_AUTH_REQUIRED challenge from the server and
 205          * send ROAMING_AUTH
 206          */
 207         if ((type = packet_read()) != SSH2_MSG_KEX_ROAMING_AUTH_REQUIRED) {
 208                 debug("expected roaming_auth_required, got %d", type);
 209                 goto fail;
 210         }
 211         roaming_auth_required();
 212
 213         /* Read ROAMING_AUTH_OK from the server */
 214         if ((type = packet_read()) != SSH2_MSG_KEX_ROAMING_AUTH_OK) {
 215                 debug("expected roaming_auth_ok, got %d", type);
 216                 goto fail;
 217         }
 218         recv_bytes = packet_get_int64() ^ oldkey2;
 219         debug("Peer received %llu bytes", (unsigned long long)recv_bytes);
 220         resend_bytes(packet_get_connection_out(), &recv_bytes);
 221
 222         resume_in_progress = 0;
 223
 224         session_resumed = 1; /* Tell clientloop */
 225
 226         return 0;
 227
 228 fail:
 229         if (kexlist)
 230                 xfree(kexlist);
 231         if (packet_get_connection_in() == packet_get_connection_out())
 232                 close(packet_get_connection_in());
 233         else {
 234                 close(packet_get_connection_in());
 235                 close(packet_get_connection_out());
 236         }
 237         return 1;
 238 }
 239
 240 int
 241 wait_for_roaming_reconnect(void)
 242 {
 243         static int reenter_guard = 0;
 244         int timeout_ms = options.connection_timeout * 1000;
 245         int c;
 246
 247         if (reenter_guard != 0)
 248                 fatal("Server refused resume, roaming timeout may be exceeded");
 249         reenter_guard = 1;
 250
 251         fprintf(stderr, "[connection suspended, press return to resume]");
 252         fflush(stderr);
 253         packet_backup_state();
 254         /* TODO Perhaps we should read from tty here */
 255         while ((c = fgetc(stdin)) != EOF) {
 256                 if (c == 'Z' - 64) {
 257                         kill(getpid(), SIGTSTP);
 258                         continue;
 259                 }
 260                 if (c != '\n' && c != '\r')
 261                         continue;
 262
 263                 if (ssh_connect(host, &hostaddr, options.port,
 264                     options.address_family, 1, &timeout_ms,
 265                     options.tcp_keep_alive, options.use_privileged_port,
 266                     options.proxy_command) == 0 && roaming_resume() == 0) {
 267                         packet_restore_state();
 268                         reenter_guard = 0;
 269                         fprintf(stderr, "[connection resumed]\n");
 270                         fflush(stderr);
 271                         return 0;
 272                 }
 273
 274                 fprintf(stderr, "[reconnect failed, press return to retry]");
 275                 fflush(stderr);
 276         }
 277         fprintf(stderr, "[exiting]\n");
 278         fflush(stderr);
 279         exit(0);
 280 }