roaming_client.c

   1 /* $OpenBSD: roaming_client.c,v 1.1 2009/10/24 11:22:37 andreas 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 <sys/queue.h>
  21 #include <sys/types.h>
  22 #include <sys/socket.h>
  23
  24 #include <inttypes.h>
  25 #include <signal.h>
  26 #include <string.h>
  27 #include <unistd.h>
  28
  29 #include <openssl/crypto.h>
  30 #include <openssl/sha.h>
  31
  32 #include "xmalloc.h"
  33 #include "buffer.h"
  34 #include "channels.h"
  35 #include "cipher.h"
  36 #include "dispatch.h"
  37 #include "clientloop.h"
  38 #include "log.h"
  39 #include "match.h"
  40 #include "misc.h"
  41 #include "packet.h"
  42 #include "ssh.h"
  43 #include "key.h"
  44 #include "kex.h"
  45 #include "readconf.h"
  46 #include "roaming.h"
  47 #include "ssh2.h"
  48 #include "sshconnect.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[SHA_DIGEST_LENGTH];
  92         EVP_MD_CTX md;
  93         Buffer b;
  94         const EVP_MD *evp_md = EVP_sha1();
  95         u_int64_t chall, oldchall;
  96
  97         chall = packet_get_int64();
  98         oldchall = packet_get_int64();
  99         if (oldchall != lastseenchall) {
 100                 key1 = oldkey1;
 101                 key2 = oldkey2;
 102         }
 103         lastseenchall = chall;
 104
 105         buffer_init(&b);
 106         buffer_put_int64(&b, cookie);
 107         buffer_put_int64(&b, chall);
 108         EVP_DigestInit(&md, evp_md);
 109         EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
 110         EVP_DigestFinal(&md, digest, NULL);
 111         buffer_free(&b);
 112
 113         packet_start(SSH2_MSG_KEX_ROAMING_AUTH);
 114         packet_put_int64(key1 ^ get_recv_bytes());
 115         packet_put_raw(digest, sizeof(digest));
 116         packet_send();
 117
 118         oldkey1 = key1;
 119         oldkey2 = key2;
 120         calculate_new_key(&key1, cookie, chall);
 121         calculate_new_key(&key2, cookie, chall);
 122
 123         debug("Received %" PRIu64 " bytes", get_recv_bytes());
 124         debug("Sent roaming_auth packet");
 125 }
 126
 127 int
 128 resume_kex(void)
 129 {
 130         /*
 131          * This should not happen - if the client sends the kex method
 132          * resume@appgate.com then the kex is done in roaming_resume().
 133          */
 134         return 1;
 135 }
 136
 137 static int
 138 roaming_resume(void)
 139 {
 140         u_int64_t recv_bytes;
 141         char *str = NULL, *kexlist = NULL, *c;
 142         int i, type;
 143         int timeout_ms = options.connection_timeout * 1000;
 144         u_int len;
 145         u_int32_t rnd = 0;
 146
 147         resume_in_progress = 1;
 148
 149         /* Exchange banners */
 150         ssh_exchange_identification(timeout_ms);
 151         packet_set_nonblocking();
 152
 153         /* Send a kexinit message with resume@appgate.com as only kex algo */
 154         packet_start(SSH2_MSG_KEXINIT);
 155         for (i = 0; i < KEX_COOKIE_LEN; i++) {
 156                 if (i % 4 == 0)
 157                         rnd = arc4random();
 158                 packet_put_char(rnd & 0xff);
 159                 rnd >>= 8;
 160         }
 161         packet_put_cstring(KEX_RESUME);
 162         for (i = 1; i < PROPOSAL_MAX; i++) {
 163                 /* kex algorithm added so start with i=1 and not 0 */
 164                 packet_put_cstring(""); /* Not used when we resume */
 165         }
 166         packet_put_char(1); /* first kex_packet follows */
 167         packet_put_int(0); /* reserved */
 168         packet_send();
 169
 170         /* Assume that resume@appgate.com will be accepted */
 171         packet_start(SSH2_MSG_KEX_ROAMING_RESUME);
 172         packet_put_int(roaming_id);
 173         packet_send();
 174
 175         /* Read the server's kexinit and check for resume@appgate.com */
 176         if ((type = packet_read()) != SSH2_MSG_KEXINIT) {
 177                 debug("expected kexinit on resume, got %d", type);
 178                 goto fail;
 179         }
 180         for (i = 0; i < KEX_COOKIE_LEN; i++)
 181                 (void)packet_get_char();
 182         kexlist = packet_get_string(&len);
 183         if (!kexlist
 184             || (str = match_list(KEX_RESUME, kexlist, NULL)) == NULL) {
 185                 debug("server doesn't allow resume");
 186                 goto fail;
 187         }
 188         xfree(str);
 189         for (i = 1; i < PROPOSAL_MAX; i++) {
 190                 /* kex algorithm taken care of so start with i=1 and not 0 */
 191                 xfree(packet_get_string(&len));
 192         }
 193         i = packet_get_char(); /* first_kex_packet_follows */
 194         if (i && (c = strchr(kexlist, ',')))
 195                 *c = 0;
 196         if (i && strcmp(kexlist, KEX_RESUME)) {
 197                 debug("server's kex guess (%s) was wrong, skipping", kexlist);
 198                 (void)packet_read(); /* Wrong guess - discard packet */
 199         }
 200
 201         /*
 202          * Read the ROAMING_AUTH_REQUIRED challenge from the server and
 203          * send ROAMING_AUTH
 204          */
 205         if ((type = packet_read()) != SSH2_MSG_KEX_ROAMING_AUTH_REQUIRED) {
 206                 debug("expected roaming_auth_required, got %d", type);
 207                 goto fail;
 208         }
 209         roaming_auth_required();
 210
 211         /* Read ROAMING_AUTH_OK from the server */
 212         if ((type = packet_read()) != SSH2_MSG_KEX_ROAMING_AUTH_OK) {
 213                 debug("expected roaming_auth_ok, got %d", type);
 214                 goto fail;
 215         }
 216         recv_bytes = packet_get_int64() ^ oldkey2;
 217         debug("Peer received %" PRIu64 " bytes", recv_bytes);
 218         resend_bytes(packet_get_connection_out(), &recv_bytes);
 219
 220         resume_in_progress = 0;
 221
 222         session_resumed = 1; /* Tell clientloop */
 223
 224         return 0;
 225
 226 fail:
 227         if (kexlist)
 228                 xfree(kexlist);
 229         if (packet_get_connection_in() == packet_get_connection_out())
 230                 close(packet_get_connection_in());
 231         else {
 232                 close(packet_get_connection_in());
 233                 close(packet_get_connection_out());
 234         }
 235         return 1;
 236 }
 237
 238 int
 239 wait_for_roaming_reconnect(void)
 240 {
 241         static int reenter_guard = 0;
 242         int timeout_ms = options.connection_timeout * 1000;
 243         int c;
 244
 245         if (reenter_guard != 0)
 246                 fatal("Server refused resume, roaming timeout may be exceeded");
 247         reenter_guard = 1;
 248
 249         fprintf(stderr, "[connection suspended, press return to resume]");
 250         fflush(stderr);
 251         packet_backup_state();
 252         /* TODO Perhaps we should read from tty here */
 253         while ((c = fgetc(stdin)) != EOF) {
 254                 if (c == 'Z' - 64) {
 255                         kill(getpid(), SIGTSTP);
 256                         continue;
 257                 }
 258                 if (c != '\n' && c != '\r')
 259                         continue;
 260
 261                 if (ssh_connect(host, &hostaddr, options.port,
 262                     options.address_family, 1, &timeout_ms,
 263                     options.tcp_keep_alive, options.use_privileged_port,
 264                     options.proxy_command) == 0 && roaming_resume() == 0) {
 265                         packet_restore_state();
 266                         reenter_guard = 0;
 267                         fprintf(stderr, "[connection resumed]\n");
 268                         fflush(stderr);
 269                         return 0;
 270                 }
 271
 272                 fprintf(stderr, "[reconnect failed, press return to retry]");
 273                 fflush(stderr);
 274         }
 275         fprintf(stderr, "[exiting]\n");
 276         fflush(stderr);
 277         exit(0);
 278 }