crypto/openssh/roaming_client.c

   1 /* $OpenBSD: roaming_client.c,v 1.9 2015/01/27 12:54:06 okan 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 #include <signal.h>
  25 #include <string.h>
  26 #include <unistd.h>
  27
  28 #include "xmalloc.h"
  29 #include "buffer.h"
  30 #include "channels.h"
  31 #include "cipher.h"
  32 #include "dispatch.h"
  33 #include "clientloop.h"
  34 #include "log.h"
  35 #include "match.h"
  36 #include "misc.h"
  37 #include "packet.h"
  38 #include "ssh.h"
  39 #include "key.h"
  40 #include "kex.h"
  41 #include "readconf.h"
  42 #include "roaming.h"
  43 #include "ssh2.h"
  44 #include "sshconnect.h"
  45 #include "digest.h"
  46
  47 /* import */
  48 extern Options options;
  49 extern char *host;
  50 extern struct sockaddr_storage hostaddr;
  51 extern int session_resumed;
  52
  53 static u_int32_t roaming_id;
  54 static u_int64_t cookie;
  55 static u_int64_t lastseenchall;
  56 static u_int64_t key1, key2, oldkey1, oldkey2;
  57
  58 void
  59 roaming_reply(int type, u_int32_t seq, void *ctxt)
  60 {
  61         if (type == SSH2_MSG_REQUEST_FAILURE) {
  62                 logit("Server denied roaming");
  63                 return;
  64         }
  65         verbose("Roaming enabled");
  66         roaming_id = packet_get_int();
  67         cookie = packet_get_int64();
  68         key1 = oldkey1 = packet_get_int64();
  69         key2 = oldkey2 = packet_get_int64();
  70         set_out_buffer_size(packet_get_int() + get_snd_buf_size());
  71         roaming_enabled = 1;
  72 }
  73
  74 void
  75 request_roaming(void)
  76 {
  77         packet_start(SSH2_MSG_GLOBAL_REQUEST);
  78         packet_put_cstring(ROAMING_REQUEST);
  79         packet_put_char(1);
  80         packet_put_int(get_recv_buf_size());
  81         packet_send();
  82         client_register_global_confirm(roaming_reply, NULL);
  83 }
  84
  85 static void
  86 roaming_auth_required(void)
  87 {
  88         u_char digest[SSH_DIGEST_MAX_LENGTH];
  89         Buffer b;
  90         u_int64_t chall, oldchall;
  91
  92         chall = packet_get_int64();
  93         oldchall = packet_get_int64();
  94         if (oldchall != lastseenchall) {
  95                 key1 = oldkey1;
  96                 key2 = oldkey2;
  97         }
  98         lastseenchall = chall;
  99
 100         buffer_init(&b);
 101         buffer_put_int64(&b, cookie);
 102         buffer_put_int64(&b, chall);
 103         if (ssh_digest_buffer(SSH_DIGEST_SHA1, &b, digest, sizeof(digest)) != 0)
 104                 fatal("%s: ssh_digest_buffer failed", __func__);
 105         buffer_free(&b);
 106
 107         packet_start(SSH2_MSG_KEX_ROAMING_AUTH);
 108         packet_put_int64(key1 ^ get_recv_bytes());
 109         packet_put_raw(digest, ssh_digest_bytes(SSH_DIGEST_SHA1));
 110         packet_send();
 111
 112         oldkey1 = key1;
 113         oldkey2 = key2;
 114         calculate_new_key(&key1, cookie, chall);
 115         calculate_new_key(&key2, cookie, chall);
 116
 117         debug("Received %llu bytes", (unsigned long long)get_recv_bytes());
 118         debug("Sent roaming_auth packet");
 119 }
 120
 121 int
 122 resume_kex(void)
 123 {
 124         /*
 125          * This should not happen - if the client sends the kex method
 126          * resume@appgate.com then the kex is done in roaming_resume().
 127          */
 128         return 1;
 129 }
 130
 131 static int
 132 roaming_resume(void)
 133 {
 134         u_int64_t recv_bytes;
 135         char *str = NULL, *kexlist = NULL, *c;
 136         int i, type;
 137         int timeout_ms = options.connection_timeout * 1000;
 138         u_int len;
 139         u_int32_t rnd = 0;
 140
 141         resume_in_progress = 1;
 142
 143         /* Exchange banners */
 144         ssh_exchange_identification(timeout_ms);
 145         packet_set_nonblocking();
 146
 147         /* Send a kexinit message with resume@appgate.com as only kex algo */
 148         packet_start(SSH2_MSG_KEXINIT);
 149         for (i = 0; i < KEX_COOKIE_LEN; i++) {
 150                 if (i % 4 == 0)
 151                         rnd = arc4random();
 152                 packet_put_char(rnd & 0xff);
 153                 rnd >>= 8;
 154         }
 155         packet_put_cstring(KEX_RESUME);
 156         for (i = 1; i < PROPOSAL_MAX; i++) {
 157                 /* kex algorithm added so start with i=1 and not 0 */
 158                 packet_put_cstring(""); /* Not used when we resume */
 159         }
 160         packet_put_char(1); /* first kex_packet follows */
 161         packet_put_int(0); /* reserved */
 162         packet_send();
 163
 164         /* Assume that resume@appgate.com will be accepted */
 165         packet_start(SSH2_MSG_KEX_ROAMING_RESUME);
 166         packet_put_int(roaming_id);
 167         packet_send();
 168
 169         /* Read the server's kexinit and check for resume@appgate.com */
 170         if ((type = packet_read()) != SSH2_MSG_KEXINIT) {
 171                 debug("expected kexinit on resume, got %d", type);
 172                 goto fail;
 173         }
 174         for (i = 0; i < KEX_COOKIE_LEN; i++)
 175                 (void)packet_get_char();
 176         kexlist = packet_get_string(&len);
 177         if (!kexlist
 178             || (str = match_list(KEX_RESUME, kexlist, NULL)) == NULL) {
 179                 debug("server doesn't allow resume");
 180                 goto fail;
 181         }
 182         free(str);
 183         for (i = 1; i < PROPOSAL_MAX; i++) {
 184                 /* kex algorithm taken care of so start with i=1 and not 0 */
 185                 free(packet_get_string(&len));
 186         }
 187         i = packet_get_char(); /* first_kex_packet_follows */
 188         if (i && (c = strchr(kexlist, ',')))
 189                 *c = 0;
 190         if (i && strcmp(kexlist, KEX_RESUME)) {
 191                 debug("server's kex guess (%s) was wrong, skipping", kexlist);
 192                 (void)packet_read(); /* Wrong guess - discard packet */
 193         }
 194
 195         /*
 196          * Read the ROAMING_AUTH_REQUIRED challenge from the server and
 197          * send ROAMING_AUTH
 198          */
 199         if ((type = packet_read()) != SSH2_MSG_KEX_ROAMING_AUTH_REQUIRED) {
 200                 debug("expected roaming_auth_required, got %d", type);
 201                 goto fail;
 202         }
 203         roaming_auth_required();
 204
 205         /* Read ROAMING_AUTH_OK from the server */
 206         if ((type = packet_read()) != SSH2_MSG_KEX_ROAMING_AUTH_OK) {
 207                 debug("expected roaming_auth_ok, got %d", type);
 208                 goto fail;
 209         }
 210         recv_bytes = packet_get_int64() ^ oldkey2;
 211         debug("Peer received %llu bytes", (unsigned long long)recv_bytes);
 212         resend_bytes(packet_get_connection_out(), &recv_bytes);
 213
 214         resume_in_progress = 0;
 215
 216         session_resumed = 1; /* Tell clientloop */
 217
 218         return 0;
 219
 220 fail:
 221         free(kexlist);
 222         if (packet_get_connection_in() == packet_get_connection_out())
 223                 close(packet_get_connection_in());
 224         else {
 225                 close(packet_get_connection_in());
 226                 close(packet_get_connection_out());
 227         }
 228         return 1;
 229 }
 230
 231 int
 232 wait_for_roaming_reconnect(void)
 233 {
 234         static int reenter_guard = 0;
 235         int timeout_ms = options.connection_timeout * 1000;
 236         int c;
 237
 238         if (reenter_guard != 0)
 239                 fatal("Server refused resume, roaming timeout may be exceeded");
 240         reenter_guard = 1;
 241
 242         fprintf(stderr, "[connection suspended, press return to resume]");
 243         fflush(stderr);
 244         packet_backup_state();
 245         /* TODO Perhaps we should read from tty here */
 246         while ((c = fgetc(stdin)) != EOF) {
 247                 if (c == 'Z' - 64) {
 248                         kill(getpid(), SIGTSTP);
 249                         continue;
 250                 }
 251                 if (c != '\n' && c != '\r')
 252                         continue;
 253
 254                 if (ssh_connect(host, NULL, &hostaddr, options.port,
 255                     options.address_family, 1, &timeout_ms,
 256                     options.tcp_keep_alive, options.use_privileged_port) == 0 &&
 257                     roaming_resume() == 0) {
 258                         packet_restore_state();
 259                         reenter_guard = 0;
 260                         fprintf(stderr, "[connection resumed]\n");
 261                         fflush(stderr);
 262                         return 0;
 263                 }
 264
 265                 fprintf(stderr, "[reconnect failed, press return to retry]");
 266                 fflush(stderr);
 267         }
 268         fprintf(stderr, "[exiting]\n");
 269         fflush(stderr);
 270         exit(0);
 271 }