summaryrefslogtreecommitdiff
path: root/src/uanytun.c
blob: 53acbaf072fc70825864cd60c1c183e33d103004 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
/*
 *  uAnytun
 *
 *  uAnytun is a tiny implementation of SATP. Unlike Anytun which is a full
 *  featured implementation uAnytun has no support for multiple connections
 *  or synchronisation. It is a small single threaded implementation intended
 *  to act as a client on small platforms.
 *  The secure anycast tunneling protocol (satp) defines a protocol used
 *  for communication between any combination of unicast and anycast
 *  tunnel endpoints.  It has less protocol overhead than IPSec in Tunnel
 *  mode and allows tunneling of every ETHER TYPE protocol (e.g.
 *  ethernet, ip, arp ...). satp directly includes cryptography and
 *  message authentication based on the methodes used by SRTP.  It is
 *  intended to deliver a generic, scaleable and secure solution for
 *  tunneling and relaying of packets of any protocol.
 *  
 *
 *  Copyright (C) 2007-2010 Christian Pointner <equinox@anytun.org>
 *
 *  This file is part of uAnytun.
 *
 *  uAnytun is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  any later version.
 *
 *  uAnytun is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with uAnytun. If not, see <http://www.gnu.org/licenses/>.
 */

#include "datatypes.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>

#include "log.h"
#include "sig_handler.h"
#include "options.h"

#include "tun.h"
#include "udp.h"

#include "plain_packet.h"
#include "encrypted_packet.h"

#include "seq_window.h"

#include "cipher.h"
#ifndef NO_CRYPT
#include "key_derivation.h"
#include "auth_algo.h"
#else
typedef u_int8_t auth_algo_t;
#endif
#include "init_crypt.h"

#include "daemon.h"
#include "sysexec.h"


int init_main_loop(options_t* opt, cipher_t* c, auth_algo_t* aa, key_derivation_t* kd, seq_win_t* seq_win)
{
  int ret = cipher_init(c, opt->cipher_);
  if(ret) {
    log_printf(ERROR, "could not initialize cipher of type %s", opt->cipher_);
    return ret;
  }
  
#ifndef NO_CRYPT
  ret = auth_algo_init(aa, opt->auth_algo_);
  if(ret) {
    log_printf(ERROR, "could not initialize auth algo of type %s", opt->auth_algo_);
    cipher_close(c);
    return ret;
  }

  ret = key_derivation_init(kd, opt->kd_prf_, opt->role_, opt->passphrase_, opt->key_.buf_, opt->key_.length_, opt->salt_.buf_, opt->salt_.length_);
  if(ret) {
    log_printf(ERROR, "could not initialize key derivation of type %s", opt->kd_prf_);
    cipher_close(c);
    auth_algo_close(aa);
    return ret;
  }
#endif

  ret = seq_win_init(seq_win, opt->seq_window_size_);
  if(ret) {
    printf("could not initialize sequence window");
    cipher_close(c);
#ifndef NO_CRYPT
    auth_algo_close(aa);
    key_derivation_close(kd);
#endif
    return ret;
  }
  return 0;
}

int process_tun_data(tun_device_t* dev, udp_t* sock, options_t* opt, plain_packet_t* plain_packet, encrypted_packet_t* encrypted_packet,
                     cipher_t* c, auth_algo_t* aa, key_derivation_t* kd, seq_nr_t seq_nr)
{
  plain_packet_set_payload_length(plain_packet, -1);
  encrypted_packet_set_length(encrypted_packet, -1);

  int len = tun_read(dev, plain_packet_get_payload(plain_packet), plain_packet_get_payload_length(plain_packet));
  if(len == -1) {
    log_printf(ERROR, "error on reading from device: %s", strerror(errno));
    return 0;
  }
  
  plain_packet_set_payload_length(plain_packet, len);
  
  if(dev->type_ == TYPE_TUN)
    plain_packet_set_type(plain_packet, PAYLOAD_TYPE_TUN);
  else if(dev->type_ == TYPE_TAP)
    plain_packet_set_type(plain_packet, PAYLOAD_TYPE_TAP);    
  else
    plain_packet_set_type(plain_packet, PAYLOAD_TYPE_UNKNOWN);

  if(!sock->remote_end_set_)
    return 0;
  
  cipher_encrypt(c, kd, kd_outbound, plain_packet, encrypted_packet, seq_nr, opt->sender_id_, opt->mux_); 
  
#ifndef NO_CRYPT
  auth_algo_generate(aa, kd, kd_outbound, encrypted_packet);
#endif
 
  len = udp_write(sock, encrypted_packet_get_packet(encrypted_packet), encrypted_packet_get_length(encrypted_packet));
  if(len == -1)
    log_printf(ERROR, "error on sending udp packet: %s", strerror(errno));

  return 0;
}

int process_sock_data(tun_device_t* dev, int fd, udp_t* sock, options_t* opt, plain_packet_t* plain_packet, encrypted_packet_t* encrypted_packet,
                      cipher_t* c, auth_algo_t* aa, key_derivation_t* kd, seq_win_t* seq_win)
{
  plain_packet_set_payload_length(plain_packet, -1);
  encrypted_packet_set_length(encrypted_packet, -1);

  udp_endpoint_t remote;
  memset(&remote, 0, sizeof(udp_endpoint_t));
  int len = udp_read(sock, fd, encrypted_packet_get_packet(encrypted_packet), encrypted_packet_get_length(encrypted_packet), &remote);
  if(len == -1) {
    log_printf(ERROR, "error on receiving udp packet: %s", strerror(errno));
    return 0;
  }
  else if(len < encrypted_packet_get_minimum_length(encrypted_packet)) {
    log_printf(WARNING, "received packet is too short");
    return 0;
  }
  encrypted_packet_set_length(encrypted_packet, len);

#ifndef NO_CRYPT
  if(!auth_algo_check_tag(aa, kd, kd_inbound, encrypted_packet)) {
    log_printf(WARNING, "wrong authentication tag, discarding packet");
    return 0;
  }
#endif
  
  if(encrypted_packet_get_mux(encrypted_packet) != opt->mux_) {
    log_printf(WARNING, "wrong mux value, discarding packet");
    return 0;
  }
  
  int result = seq_win_check_and_add(seq_win, encrypted_packet_get_sender_id(encrypted_packet), encrypted_packet_get_seq_nr(encrypted_packet));
  if(result > 0) {
    log_printf(WARNING, "detected replay attack, discarding packet");
    return 0;
  }
  else if(result < 0) {
    log_printf(ERROR, "memory error at sequence window");
    return -2;
  }
   
  udp_set_active_sock(sock, fd);
  if(memcmp(&remote, &(sock->remote_end_), sizeof(remote))) {
    memcpy(&(sock->remote_end_), &remote, sizeof(remote));
    sock->remote_end_set_ = 1;
    char* addrstring = udp_endpoint_to_string(remote);
    log_printf(NOTICE, "autodetected remote host changed %s", addrstring);
    free(addrstring);
  }

  if(encrypted_packet_get_payload_length(encrypted_packet) <= plain_packet_get_header_length()) {
    log_printf(WARNING, "ignoring packet with zero length payload");
    return 0;
  }

  int ret = cipher_decrypt(c, kd, kd_inbound, encrypted_packet, plain_packet); 
  if(ret) 
    return ret;
 
  len = tun_write(dev, plain_packet_get_payload(plain_packet), plain_packet_get_payload_length(plain_packet));
  if(len == -1)
    log_printf(ERROR, "error on writing to device: %s", strerror(errno));
  
  return 0;
}


int main_loop(tun_device_t* dev, udp_t* sock, options_t* opt)
{
  log_printf(INFO, "entering main loop");

  plain_packet_t plain_packet;
  plain_packet_init(&plain_packet);
  encrypted_packet_t encrypted_packet;
  encrypted_packet_init(&encrypted_packet, opt->auth_tag_length_);
  seq_nr_t seq_nr = 0;
  fd_set readfds, readyfds;

  cipher_t c;
  auth_algo_t aa;
  key_derivation_t kd;
  seq_win_t seq_win;

  int ret = init_main_loop(opt, &c, &aa, &kd, &seq_win);
  if(ret)
    return ret;

  FD_ZERO(&readfds);
  FD_SET(dev->fd_, &readfds);
  int nfds = udp_init_fd_set(sock, &readfds);
  nfds = dev->fd_ > nfds ? dev->fd_ : nfds;

  int return_value = 0;
  int sig_fd = signal_init();
  if(sig_fd < 0)
    return_value -1;

  FD_SET(sig_fd, &readfds);
  nfds = (nfds < sig_fd) ? sig_fd : nfds;

  while(!return_value) {
    memcpy(&readyfds, &readfds, sizeof(readyfds));
    int ret = select(nfds + 1, &readyfds, NULL, NULL, NULL);
    if(ret == -1 && errno != EINTR) {
      log_printf(ERROR, "select returned with error: %s", strerror(errno));
      return_value = -1;
      break;
    }
    if(!ret || ret == -1)
      continue;

    if(FD_ISSET(sig_fd, &readyfds)) {
      if(signal_handle()) {
        return_value = 1;
        break;
      }
    }

    if(FD_ISSET(dev->fd_, &readyfds)) {
      return_value = process_tun_data(dev, sock, opt, &plain_packet, &encrypted_packet, &c, &aa, &kd, seq_nr);
      seq_nr++;
      if(return_value)
        break;
    }

    udp_socket_t* s = sock->socks_;
    while(s) {
      if(FD_ISSET(s->fd_, &readyfds)) {
        return_value = process_sock_data(dev, s->fd_, sock, opt, &plain_packet, &encrypted_packet, &c, &aa, &kd, &seq_win); 
        if(return_value)
          break;
      }
      s = s->next_;
    }
  }

  cipher_close(&c);
#ifndef NO_CRYPT
  auth_algo_close(&aa);
  key_derivation_close(&kd);
#endif
  seq_win_clear(&seq_win);
  signal_stop();

  return return_value;
}

int main(int argc, char* argv[])
{
  log_init();

  options_t opt;
  int ret = options_parse(&opt, argc, argv);
  if(ret) {
    if(ret > 0) {
      fprintf(stderr, "syntax error near: %s\n\n", argv[ret]);
    }
    if(ret == -2) {
      fprintf(stderr, "memory error on options_parse, exitting\n");
    }
    if(ret == -3) {
      fprintf(stderr, "syntax error: -4 and -6 are mutual exclusive\n\n");
    }
    if(ret == -4) {
      fprintf(stderr, "syntax error: unknown role name\n\n");
    }
    if(ret == -5) {
      options_print_version();
    }

    if(ret != -2 && ret != -5) 
      options_print_usage();

    if(ret == -1 || ret == -5)
      ret = 0;

    options_clear(&opt);
    log_close();
    exit(ret);
  }
  string_list_element_t* tmp = opt.log_targets_.first_;
  while(tmp) {
    ret = log_add_target(tmp->string_);
    if(ret) {
      switch(ret) {
      case -2: fprintf(stderr, "memory error on log_add_target, exitting\n"); break;
      case -3: fprintf(stderr, "unknown log target: '%s', exitting\n", tmp->string_); break;
      case -4: fprintf(stderr, "this log target is only allowed once: '%s', exitting\n", tmp->string_); break;
      default: fprintf(stderr, "syntax error near: '%s', exitting\n", tmp->string_); break;
      }
        
      options_clear(&opt);
      log_close();
      exit(ret);
    }
    tmp = tmp->next_;
  }

  log_printf(NOTICE, "just started...");
  options_parse_post(&opt);

  priv_info_t priv;
  if(opt.username_)
    if(priv_init(&priv, opt.username_, opt.groupname_)) {
      options_clear(&opt);
      log_close();
      exit(-1);
    }

  ret = init_crypt();
  if(ret) {
    log_printf(ERROR, "error on crpyto initialization, exitting");
    options_clear(&opt);
    log_close();
    exit(ret);
  }

  tun_device_t dev;
  ret = tun_init(&dev, opt.dev_name_, opt.dev_type_, opt.ifconfig_param_.net_addr_, opt.ifconfig_param_.prefix_length_);
  if(ret) {
    log_printf(ERROR, "error on tun_init, exitting");
    options_clear(&opt);
    log_close();
    exit(ret);
  }
  log_printf(NOTICE, "dev of type '%s' opened, actual name is '%s'", tun_get_type_string(&dev), dev.actual_name_);

  if(opt.post_up_script_) {
    log_printf(NOTICE, "executing post-up script '%s'", opt.post_up_script_);
    char* const argv[] = { opt.post_up_script_, dev.actual_name_, NULL };
    char* const evp[] = { NULL };
    int ret = uanytun_exec(opt.post_up_script_, argv, evp);
  }


  udp_t sock;
  ret = udp_init(&sock, opt.local_addr_, opt.local_port_, opt.resolv_addr_type_);
  if(ret) {
    log_printf(ERROR, "error on udp_init, exitting");
    tun_close(&dev);
    options_clear(&opt);
    log_close();
    exit(ret);
  }

  if(opt.remote_addr_) {
    if(!udp_set_remote(&sock, opt.remote_addr_, opt.remote_port_, opt.resolv_addr_type_)) {
      char* remote_string = udp_get_remote_end_string(&sock);
      if(remote_string) {
        log_printf(NOTICE, "set remote end to: %s", remote_string);
        free(remote_string);
      }
    }
  }


  FILE* pid_file = NULL;
  if(opt.pid_file_) {
    pid_file = fopen(opt.pid_file_, "w");
    if(!pid_file) {
      log_printf(WARNING, "unable to open pid file: %s", strerror(errno));
    }
  }

  if(opt.chroot_dir_)
    if(do_chroot(opt.chroot_dir_)) {
      tun_close(&dev);
      udp_close(&sock);
      options_clear(&opt);
      log_close();
      exit(-1);
    }
  if(opt.username_)
    if(priv_drop(&priv)) {
      tun_close(&dev);
      udp_close(&sock);
      options_clear(&opt);
      log_close();
      exit(-1);
    }  

  if(opt.daemonize_) {
    pid_t oldpid = getpid();
    daemonize();
    log_printf(INFO, "running in background now (old pid: %d)", oldpid);
  }

  if(pid_file) {
    pid_t pid = getpid();
    fprintf(pid_file, "%d", pid);
    fclose(pid_file);
  }

  ret = main_loop(&dev, &sock, &opt);

  tun_close(&dev);
  udp_close(&sock);
  options_clear(&opt);

  if(!ret)
    log_printf(NOTICE, "normal shutdown");
  else if(ret < 0)
    log_printf(NOTICE, "shutdown after error");
  else
    log_printf(NOTICE, "shutdown after signal");

  log_close();

  return ret;
}