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 <sys/queue.h>
  19 #include <sys/types.h>
  20 #include <sys/socket.h>
  21
  22 #include <inttypes.h>
  23 #include <signal.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26
  27 #include <openssl/crypto.h>
  28 #include <openssl/sha.h>
  29
  30 #include "xmalloc.h"
  31 #include "buffer.h"
  32 #include "channels.h"
  33 #include "cipher.h"
  34 #include "dispatch.h"
  35 #include "clientloop.h"
  36 #include "log.h"
  37 #include "match.h"
  38 #include "misc.h"
  39 #include "packet.h"
  40 #include "ssh.h"
  41 #include "key.h"
  42 #include "kex.h"
  43 #include "readconf.h"
  44 #include "roaming.h"
  45 #include "ssh2.h"
  46 #include "sshconnect.h"
  47
  48 /* import */
  49 extern Options options;
  50 extern char *host;
  51 extern struct sockaddr_storage hostaddr;
  52 extern int session_resumed;
  53
  54 static u_int32_t roaming_id;
  55 static u_int64_t cookie;
  56 static u_int64_t lastseenchall;
  57 static u_int64_t key1, key2, oldkey1, oldkey2;
  58
  59 void
  60 roaming_reply(int type, u_int32_t seq, void *ctxt)
  61 {
  62         if (type == SSH2_MSG_REQUEST_FAILURE) {
  63                 logit("Server denied roaming");
  64                 return;
  65         }
  66         verbose("Roaming enabled");
  67         roaming_id = packet_get_int();
  68         cookie = packet_get_int64();
  69         key1 = oldkey1 = packet_get_int64();
  70         key2 = oldkey2 = packet_get_int64();
  71         set_out_buffer_size(packet_get_int() +  get_snd_buf_size());
  72         roaming_enabled = 1;
  73 }
  74
  75 void
  76 request_roaming(void)
  77 {
  78         packet_start(SSH2_MSG_GLOBAL_REQUEST);
  79         packet_put_cstring(ROAMING_REQUEST);
  80         packet_put_char(1);
  81         packet_put_int(get_recv_buf_size());
  82         packet_send();
  83         client_register_global_confirm(roaming_reply, NULL);
  84 }
  85
  86 static void
  87 roaming_auth_required(void)
  88 {
  89         u_char digest[SHA_DIGEST_LENGTH];
  90         EVP_MD_CTX md;
  91         Buffer b;
  92         const EVP_MD *evp_md = EVP_sha1();
  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         EVP_DigestInit(&md, evp_md);
 107         EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
 108         EVP_DigestFinal(&md, digest, NULL);
 109         buffer_free(&b);
 110
 111         packet_start(SSH2_MSG_KEX_ROAMING_AUTH);
 112         packet_put_int64(key1 ^ get_recv_bytes());
 113         packet_put_raw(digest, sizeof(digest));
 114         packet_send();
 115
 116         oldkey1 = key1;
 117         oldkey2 = key2;
 118         calculate_new_key(&key1, cookie, chall);
 119         calculate_new_key(&key2, cookie, chall);
 120
 121         debug("Received %" PRIu64 " bytes", get_recv_bytes());
 122         debug("Sent roaming_auth packet");
 123 }
 124
 125 int
 126 resume_kex(void)
 127 {
 128         /*
 129          * This should not happen - if the client sends the kex method
 130          * resume@appgate.com then the kex is done in roaming_resume().
 131          */
 132         return 1;
 133 }
 134
 135 static int
 136 roaming_resume(void)
 137 {
 138         u_int64_t recv_bytes;
 139         char *str = NULL, *kexlist = NULL, *c;
 140         int i, type;
 141         int timeout_ms = options.connection_timeout * 1000;
 142         u_int len;
 143         u_int32_t rnd = 0;
 144
 145         resume_in_progress = 1;
 146
 147         /* Exchange banners */
 148         ssh_exchange_identification(timeout_ms);
 149         packet_set_nonblocking();
 150
 151         /* Send a kexinit message with resume@appgate.com as only kex algo */
 152         packet_start(SSH2_MSG_KEXINIT);
 153         for (i = 0; i < KEX_COOKIE_LEN; i++) {
 154                 if (i % 4 == 0)
 155                         rnd = arc4random();
 156                 packet_put_char(rnd & 0xff);
 157                 rnd >>= 8;
 158         }
 159         packet_put_cstring(KEX_RESUME);
 160         for (i = 1; i < PROPOSAL_MAX; i++) {
 161                 /* kex algorithm added so start with i=1 and not 0 */
 162                 packet_put_cstring(""); /* Not used when we resume */
 163         }
 164         packet_put_char(1); /* first kex_packet follows */
 165         packet_put_int(0); /* reserved */
 166         packet_send();
 167
 168         /* Assume that resume@appgate.com will be accepted */
 169         packet_start(SSH2_MSG_KEX_ROAMING_RESUME);
 170         packet_put_int(roaming_id);
 171         packet_send();
 172
 173         /* Read the server's kexinit and check for resume@appgate.com */
 174         if ((type = packet_read()) != SSH2_MSG_KEXINIT) {
 175                 debug("expected kexinit on resume, got %d", type);
 176                 goto fail;
 177         }
 178         for (i = 0; i < KEX_COOKIE_LEN; i++)
 179                 (void)packet_get_char();
 180         kexlist = packet_get_string(&len);
 181         if (!kexlist
 182             || (str = match_list(KEX_RESUME, kexlist, NULL)) == NULL) {
 183                 debug("server doesn't allow resume");
 184                 goto fail;
 185         }
 186         xfree(str);
 187         for (i = 1; i < PROPOSAL_MAX; i++) {
 188                 /* kex algorithm taken care of so start with i=1 and not 0 */
 189                 xfree(packet_get_string(&len));
 190         }
 191         i = packet_get_char(); /* first_kex_packet_follows */
 192         if (i && (c = strchr(kexlist, ',')))
 193                 *c = 0;
 194         if (i && strcmp(kexlist, KEX_RESUME)) {
 195                 debug("server's kex guess (%s) was wrong, skipping", kexlist);
 196                 (void)packet_read(); /* Wrong guess - discard packet */
 197         }
 198
 199         /*
 200          * Read the ROAMING_AUTH_REQUIRED challenge from the server and
 201          * send ROAMING_AUTH
 202          */
 203         if ((type = packet_read()) != SSH2_MSG_KEX_ROAMING_AUTH_REQUIRED) {
 204                 debug("expected roaming_auth_required, got %d", type);
 205                 goto fail;
 206         }
 207         roaming_auth_required();
 208
 209         /* Read ROAMING_AUTH_OK from the server */
 210         if ((type = packet_read()) != SSH2_MSG_KEX_ROAMING_AUTH_OK) {
 211                 debug("expected roaming_auth_ok, got %d", type);
 212                 goto fail;
 213         }
 214         recv_bytes = packet_get_int64() ^ oldkey2;
 215         debug("Peer received %" PRIu64 " bytes", recv_bytes);
 216         resend_bytes(packet_get_connection_out(), &recv_bytes);
 217
 218         resume_in_progress = 0;
 219
 220         session_resumed = 1; /* Tell clientloop */
 221
 222         return 0;
 223
 224 fail:
 225         if (kexlist)
 226                 xfree(kexlist);
 227         if (packet_get_connection_in() == packet_get_connection_out())
 228                 close(packet_get_connection_in());
 229         else {
 230                 close(packet_get_connection_in());
 231                 close(packet_get_connection_out());
 232         }
 233         return 1;
 234 }
 235
 236 int
 237 wait_for_roaming_reconnect(void)
 238 {
 239         static int reenter_guard = 0;
 240         int timeout_ms = options.connection_timeout * 1000;
 241         int c;
 242
 243         if (reenter_guard != 0)
 244                 fatal("Server refused resume, roaming timeout may be exceeded");
 245         reenter_guard = 1;
 246
 247         fprintf(stderr, "[connection suspended, press return to resume]");
 248         fflush(stderr);
 249         packet_backup_state();
 250         /* TODO Perhaps we should read from tty here */
 251         while ((c = fgetc(stdin)) != EOF) {
 252                 if (c == 'Z' - 64) {
 253                         kill(getpid(), SIGTSTP);
 254                         continue;
 255                 }
 256                 if (c != '\n' && c != '\r')
 257                         continue;
 258
 259                 if (ssh_connect(host, &hostaddr, options.port,
 260                     options.address_family, 1, &timeout_ms,
 261                     options.tcp_keep_alive, options.use_privileged_port,
 262                     options.proxy_command) == 0 && roaming_resume() == 0) {
 263                         packet_restore_state();
 264                         reenter_guard = 0;
 265                         fprintf(stderr, "[connection resumed]\n");
 266                         fflush(stderr);
 267                         return 0;
 268                 }
 269
 270                 fprintf(stderr, "[reconnect failed, press return to retry]");
 271                 fflush(stderr);
 272         }
 273         fprintf(stderr, "[exiting]\n");
 274         fflush(stderr);
 275         exit(0);
 276 }