crypto/openssh/roaming_client.c

   1 /* $OpenBSD: roaming_client.c,v 1.8 2014/04/29 18:01:49 markus 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 "xmalloc.h"
  32 #include "buffer.h"
  33 #include "channels.h"
  34 #include "cipher.h"
  35 #include "dispatch.h"
  36 #include "clientloop.h"
  37 #include "log.h"
  38 #include "match.h"
  39 #include "misc.h"
  40 #include "packet.h"
  41 #include "ssh.h"
  42 #include "key.h"
  43 #include "kex.h"
  44 #include "readconf.h"
  45 #include "roaming.h"
  46 #include "ssh2.h"
  47 #include "sshconnect.h"
  48 #include "digest.h"
  49
  50 /* import */
  51 extern Options options;
  52 extern char *host;
  53 extern struct sockaddr_storage hostaddr;
  54 extern int session_resumed;
  55
  56 static u_int32_t roaming_id;
  57 static u_int64_t cookie;
  58 static u_int64_t lastseenchall;
  59 static u_int64_t key1, key2, oldkey1, oldkey2;
  60
  61 void
  62 roaming_reply(int type, u_int32_t seq, void *ctxt)
  63 {
  64         if (type == SSH2_MSG_REQUEST_FAILURE) {
  65                 logit("Server denied roaming");
  66                 return;
  67         }
  68         verbose("Roaming enabled");
  69         roaming_id = packet_get_int();
  70         cookie = packet_get_int64();
  71         key1 = oldkey1 = packet_get_int64();
  72         key2 = oldkey2 = packet_get_int64();
  73         set_out_buffer_size(packet_get_int() + get_snd_buf_size());
  74         roaming_enabled = 1;
  75 }
  76
  77 void
  78 request_roaming(void)
  79 {
  80         packet_start(SSH2_MSG_GLOBAL_REQUEST);
  81         packet_put_cstring(ROAMING_REQUEST);
  82         packet_put_char(1);
  83         packet_put_int(get_recv_buf_size());
  84         packet_send();
  85         client_register_global_confirm(roaming_reply, NULL);
  86 }
  87
  88 static void
  89 roaming_auth_required(void)
  90 {
  91         u_char digest[SSH_DIGEST_MAX_LENGTH];
  92         Buffer b;
  93         u_int64_t chall, oldchall;
  94
  95         chall = packet_get_int64();
  96         oldchall = packet_get_int64();
  97         if (oldchall != lastseenchall) {
  98                 key1 = oldkey1;
  99                 key2 = oldkey2;
 100         }
 101         lastseenchall = chall;
 102
 103         buffer_init(&b);
 104         buffer_put_int64(&b, cookie);
 105         buffer_put_int64(&b, chall);
 106         if (ssh_digest_buffer(SSH_DIGEST_SHA1, &b, digest, sizeof(digest)) != 0)
 107                 fatal("%s: ssh_digest_buffer failed", __func__);
 108         buffer_free(&b);
 109
 110         packet_start(SSH2_MSG_KEX_ROAMING_AUTH);
 111         packet_put_int64(key1 ^ get_recv_bytes());
 112         packet_put_raw(digest, ssh_digest_bytes(SSH_DIGEST_SHA1));
 113         packet_send();
 114
 115         oldkey1 = key1;
 116         oldkey2 = key2;
 117         calculate_new_key(&key1, cookie, chall);
 118         calculate_new_key(&key2, cookie, chall);
 119
 120         debug("Received %llu bytes", (unsigned long long)get_recv_bytes());
 121         debug("Sent roaming_auth packet");
 122 }
 123
 124 int
 125 resume_kex(void)
 126 {
 127         /*
 128          * This should not happen - if the client sends the kex method
 129          * resume@appgate.com then the kex is done in roaming_resume().
 130          */
 131         return 1;
 132 }
 133
 134 static int
 135 roaming_resume(void)
 136 {
 137         u_int64_t recv_bytes;
 138         char *str = NULL, *kexlist = NULL, *c;
 139         int i, type;
 140         int timeout_ms = options.connection_timeout * 1000;
 141         u_int len;
 142         u_int32_t rnd = 0;
 143
 144         resume_in_progress = 1;
 145
 146         /* Exchange banners */
 147         ssh_exchange_identification(timeout_ms);
 148         packet_set_nonblocking();
 149
 150         /* Send a kexinit message with resume@appgate.com as only kex algo */
 151         packet_start(SSH2_MSG_KEXINIT);
 152         for (i = 0; i < KEX_COOKIE_LEN; i++) {
 153                 if (i % 4 == 0)
 154                         rnd = arc4random();
 155                 packet_put_char(rnd & 0xff);
 156                 rnd >>= 8;
 157         }
 158         packet_put_cstring(KEX_RESUME);
 159         for (i = 1; i < PROPOSAL_MAX; i++) {
 160                 /* kex algorithm added so start with i=1 and not 0 */
 161                 packet_put_cstring(""); /* Not used when we resume */
 162         }
 163         packet_put_char(1); /* first kex_packet follows */
 164         packet_put_int(0); /* reserved */
 165         packet_send();
 166
 167         /* Assume that resume@appgate.com will be accepted */
 168         packet_start(SSH2_MSG_KEX_ROAMING_RESUME);
 169         packet_put_int(roaming_id);
 170         packet_send();
 171
 172         /* Read the server's kexinit and check for resume@appgate.com */
 173         if ((type = packet_read()) != SSH2_MSG_KEXINIT) {
 174                 debug("expected kexinit on resume, got %d", type);
 175                 goto fail;
 176         }
 177         for (i = 0; i < KEX_COOKIE_LEN; i++)
 178                 (void)packet_get_char();
 179         kexlist = packet_get_string(&len);
 180         if (!kexlist
 181             || (str = match_list(KEX_RESUME, kexlist, NULL)) == NULL) {
 182                 debug("server doesn't allow resume");
 183                 goto fail;
 184         }
 185         free(str);
 186         for (i = 1; i < PROPOSAL_MAX; i++) {
 187                 /* kex algorithm taken care of so start with i=1 and not 0 */
 188                 free(packet_get_string(&len));
 189         }
 190         i = packet_get_char(); /* first_kex_packet_follows */
 191         if (i && (c = strchr(kexlist, ',')))
 192                 *c = 0;
 193         if (i && strcmp(kexlist, KEX_RESUME)) {
 194                 debug("server's kex guess (%s) was wrong, skipping", kexlist);
 195                 (void)packet_read(); /* Wrong guess - discard packet */
 196         }
 197
 198         /*
 199          * Read the ROAMING_AUTH_REQUIRED challenge from the server and
 200          * send ROAMING_AUTH
 201          */
 202         if ((type = packet_read()) != SSH2_MSG_KEX_ROAMING_AUTH_REQUIRED) {
 203                 debug("expected roaming_auth_required, got %d", type);
 204                 goto fail;
 205         }
 206         roaming_auth_required();
 207
 208         /* Read ROAMING_AUTH_OK from the server */
 209         if ((type = packet_read()) != SSH2_MSG_KEX_ROAMING_AUTH_OK) {
 210                 debug("expected roaming_auth_ok, got %d", type);
 211                 goto fail;
 212         }
 213         recv_bytes = packet_get_int64() ^ oldkey2;
 214         debug("Peer received %llu bytes", (unsigned long long)recv_bytes);
 215         resend_bytes(packet_get_connection_out(), &recv_bytes);
 216
 217         resume_in_progress = 0;
 218
 219         session_resumed = 1; /* Tell clientloop */
 220
 221         return 0;
 222
 223 fail:
 224         free(kexlist);
 225         if (packet_get_connection_in() == packet_get_connection_out())
 226                 close(packet_get_connection_in());
 227         else {
 228                 close(packet_get_connection_in());
 229                 close(packet_get_connection_out());
 230         }
 231         return 1;
 232 }
 233
 234 int
 235 wait_for_roaming_reconnect(void)
 236 {
 237         static int reenter_guard = 0;
 238         int timeout_ms = options.connection_timeout * 1000;
 239         int c;
 240
 241         if (reenter_guard != 0)
 242                 fatal("Server refused resume, roaming timeout may be exceeded");
 243         reenter_guard = 1;
 244
 245         fprintf(stderr, "[connection suspended, press return to resume]");
 246         fflush(stderr);
 247         packet_backup_state();
 248         /* TODO Perhaps we should read from tty here */
 249         while ((c = fgetc(stdin)) != EOF) {
 250                 if (c == 'Z' - 64) {
 251                         kill(getpid(), SIGTSTP);
 252                         continue;
 253                 }
 254                 if (c != '\n' && c != '\r')
 255                         continue;
 256
 257                 if (ssh_connect(host, NULL, &hostaddr, options.port,
 258                     options.address_family, 1, &timeout_ms,
 259                     options.tcp_keep_alive, options.use_privileged_port) == 0 &&
 260                     roaming_resume() == 0) {
 261                         packet_restore_state();
 262                         reenter_guard = 0;
 263                         fprintf(stderr, "[connection resumed]\n");
 264                         fflush(stderr);
 265                         return 0;
 266                 }
 267
 268                 fprintf(stderr, "[reconnect failed, press return to retry]");
 269                 fflush(stderr);
 270         }
 271         fprintf(stderr, "[exiting]\n");
 272         fflush(stderr);
 273         exit(0);
 274 }