summaryrefslogtreecommitdiffstats
path: root/libvncclient/tls_openssl.c
blob: b7a0911d0f8de74ea82969d5b0230f8c7caeeb54 (plain)
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
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
/*
 *  Copyright (C) 2012 Philip Van Hoof <philip@codeminded.be>
 *  Copyright (C) 2009 Vic Lee.
 *
 *  This 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 2 of the License, or
 *  (at your option) any later version.
 *
 *  This software 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 this software; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
 *  USA.
 */

#include <rfb/rfbclient.h>
#include <errno.h>

#include <openssl/err.h>
#include <openssl/ssl.h>
#include <openssl/x509.h>
#include <openssl/rand.h>
#include <openssl/x509.h>

#include <pthread.h>

#include "tls.h"

static rfbBool rfbTLSInitialized = FALSE;
static pthread_mutex_t *mutex_buf = NULL;

struct CRYPTO_dynlock_value {
	pthread_mutex_t mutex;
};

static void locking_function(int mode, int n, const char *file, int line)
{
	if (mode & CRYPTO_LOCK)
		pthread_mutex_lock(&mutex_buf[n]);
	else
		pthread_mutex_unlock(&mutex_buf[n]);
}

static unsigned long id_function(void)
{
	return ((unsigned long) pthread_self());
}

static struct CRYPTO_dynlock_value *dyn_create_function(const char *file, int line)
{
	struct CRYPTO_dynlock_value *value;

	value = (struct CRYPTO_dynlock_value *)
		malloc(sizeof(struct CRYPTO_dynlock_value));
	if (!value)
		goto err;
	pthread_mutex_init(&value->mutex, NULL);

	return value;

err:
	return (NULL);
}

static void dyn_lock_function (int mode, struct CRYPTO_dynlock_value *l, const char *file, int line)
{
	if (mode & CRYPTO_LOCK)
		pthread_mutex_lock(&l->mutex);
	else
		pthread_mutex_unlock(&l->mutex);
}


static void
dyn_destroy_function(struct CRYPTO_dynlock_value *l, const char *file, int line)
{
	pthread_mutex_destroy(&l->mutex);
	free(l);
}


static int
ssl_errno (SSL *ssl, int ret)
{
	switch (SSL_get_error (ssl, ret)) {
	case SSL_ERROR_NONE:
		return 0;
	case SSL_ERROR_ZERO_RETURN:
		/* this one does not map well at all */
		//d(printf ("ssl_errno: SSL_ERROR_ZERO_RETURN\n"));
		return EINVAL;
	case SSL_ERROR_WANT_READ:   /* non-fatal; retry */
	case SSL_ERROR_WANT_WRITE:  /* non-fatal; retry */
		//d(printf ("ssl_errno: SSL_ERROR_WANT_[READ,WRITE]\n"));
		return EAGAIN;
	case SSL_ERROR_SYSCALL:
		//d(printf ("ssl_errno: SSL_ERROR_SYSCALL\n"));
		return EINTR;
	case SSL_ERROR_SSL:
		//d(printf ("ssl_errno: SSL_ERROR_SSL  <-- very useful error...riiiiight\n"));
		return EINTR;
	default:
		//d(printf ("ssl_errno: default error\n"));
		return EINTR;
	}
}

static rfbBool
InitializeTLS(void)
{
  int i;

  if (rfbTLSInitialized) return TRUE;

  mutex_buf = malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t));
  if (mutex_buf == NULL) {
    rfbClientLog("Failed to initialized OpenSSL: memory.\n");
    return (-1);
  }

  for (i = 0; i < CRYPTO_num_locks(); i++)
    pthread_mutex_init(&mutex_buf[i], NULL);

  CRYPTO_set_locking_callback(locking_function);
  CRYPTO_set_id_callback(id_function);
  CRYPTO_set_dynlock_create_callback(dyn_create_function);
  CRYPTO_set_dynlock_lock_callback(dyn_lock_function);
  CRYPTO_set_dynlock_destroy_callback(dyn_destroy_function);
  SSL_load_error_strings();
  SSLeay_add_ssl_algorithms();
  RAND_load_file("/dev/urandom", 1024);

  rfbClientLog("OpenSSL initialized.\n");
  rfbTLSInitialized = TRUE;
  return TRUE;
}

static int
ssl_verify (int ok, X509_STORE_CTX *ctx)
{
  unsigned char md5sum[16], fingerprint[40], *f;
  rfbClient *client;
  int err, i;
  unsigned int md5len;
  //char buf[257];
  X509 *cert;
  SSL *ssl;

  if (ok)
    return TRUE;

  ssl = X509_STORE_CTX_get_ex_data (ctx, SSL_get_ex_data_X509_STORE_CTX_idx ());

  client = SSL_CTX_get_app_data (ssl->ctx);

  cert = X509_STORE_CTX_get_current_cert (ctx);
  err = X509_STORE_CTX_get_error (ctx);

  /* calculate the MD5 hash of the raw certificate */
  md5len = sizeof (md5sum);
  X509_digest (cert, EVP_md5 (), md5sum, &md5len);
  for (i = 0, f = fingerprint; i < 16; i++, f += 3)
    sprintf ((char *) f, "%.2x%c", md5sum[i], i != 15 ? ':' : '\0');

#define GET_STRING(name) X509_NAME_oneline (name, buf, 256)

  /* TODO: Don't just ignore certificate checks

   fingerprint = key to check in db

   GET_STRING (X509_get_issuer_name (cert));
   GET_STRING (X509_get_subject_name (cert));
   cert->valid (bool: GOOD or BAD) */

  ok = TRUE;

  return ok;
}

static int sock_read_ready(SSL *ssl, uint32_t ms)
{
	int r = 0;
	fd_set fds;
	struct timeval tv;

	FD_ZERO(&fds);

	FD_SET(SSL_get_fd(ssl), &fds);

	tv.tv_sec = ms / 1000;
	tv.tv_usec = (ms % 1000) * 1000;
	
	r = select (SSL_get_fd(ssl) + 1, &fds, NULL, NULL, &tv); 

	return r;
}

static int wait_for_data(SSL *ssl, int ret, int timeout)
{
  int err;
  int retval = 1;

  err = SSL_get_error(ssl, ret);
	
  switch(err)
  {
    case SSL_ERROR_WANT_READ:
    case SSL_ERROR_WANT_WRITE:
      ret = sock_read_ready(ssl, timeout*1000);
			
      if (ret == -1) {
        retval = 2;
      }
				
      break;
      default:
      retval = 3;
      break;
   }
	
  ERR_clear_error();
				
  return retval;
}

static SSL *
open_ssl_connection (rfbClient *client, int sockfd, rfbBool anonTLS)
{
  SSL_CTX *ssl_ctx = NULL;
  SSL *ssl = NULL;
  int n, finished = 0;

  ssl_ctx = SSL_CTX_new (SSLv23_client_method ());
  SSL_CTX_set_default_verify_paths (ssl_ctx);
  SSL_CTX_set_verify (ssl_ctx, SSL_VERIFY_NONE, &ssl_verify);
  ssl = SSL_new (ssl_ctx);

  /* TODO: finetune this list, take into account anonTLS bool */
  SSL_set_cipher_list(ssl, "ALL");

  SSL_set_fd (ssl, sockfd);
  SSL_CTX_set_app_data (ssl_ctx, client);

  do
  {
    n = SSL_connect(ssl);
		
    if (n != 1) 
    {
      if (wait_for_data(ssl, n, 1) != 1) 
      {
        finished = 1; 
        if (ssl->ctx)
          SSL_CTX_free (ssl->ctx);
        SSL_free(ssl);
        SSL_shutdown (ssl);

        return NULL;
      }
    }
  } while( n != 1 && finished != 1 );

  return ssl;
}


static rfbBool
InitializeTLSSession(rfbClient* client, rfbBool anonTLS)
{
  if (client->tlsSession) return TRUE;

  client->tlsSession = open_ssl_connection (client, client->sock, anonTLS);

  if (!client->tlsSession)
    return FALSE;

  rfbClientLog("TLS session initialized.\n");

  return TRUE;
}

static rfbBool
SetTLSAnonCredential(rfbClient* client)
{
  rfbClientLog("TLS anonymous credential created.\n");
  return TRUE;
}

static rfbBool
HandshakeTLS(rfbClient* client)
{
  int timeout = 15;
  int ret;

return TRUE;

  while (timeout > 0 && (ret = SSL_do_handshake(client->tlsSession)) < 0)
  {
    if (ret != -1)
    {
      rfbClientLog("TLS handshake blocking.\n");
      sleep(1);
      timeout--;
      continue;
    }
    rfbClientLog("TLS handshake failed: -.\n");
    FreeTLS(client);
    return FALSE;
  }

  if (timeout <= 0)
  {
    rfbClientLog("TLS handshake timeout.\n");
    FreeTLS(client);
    return FALSE;
  }

  rfbClientLog("TLS handshake done.\n");
  return TRUE;
}

/* VeNCrypt sub auth. 1 byte auth count, followed by count * 4 byte integers */
static rfbBool
ReadVeNCryptSecurityType(rfbClient* client, uint32_t *result)
{
    uint8_t count=0;
    uint8_t loop=0;
    uint8_t flag=0;
    uint32_t tAuth[256], t;
    char buf1[500],buf2[10];
    uint32_t authScheme;

    if (!ReadFromRFBServer(client, (char *)&count, 1)) return FALSE;

    if (count==0)
    {
        rfbClientLog("List of security types is ZERO. Giving up.\n");
        return FALSE;
    }

    if (count>sizeof(tAuth))
    {
        rfbClientLog("%d security types are too many; maximum is %d\n", count, sizeof(tAuth));
        return FALSE;
    }

    rfbClientLog("We have %d security types to read\n", count);
    authScheme=0;
    /* now, we have a list of available security types to read ( uint8_t[] ) */
    for (loop=0;loop<count;loop++)
    {
        if (!ReadFromRFBServer(client, (char *)&tAuth[loop], 4)) return FALSE;
        t=rfbClientSwap32IfLE(tAuth[loop]);
        rfbClientLog("%d) Received security type %d\n", loop, t);
        if (flag) continue;
        if (t==rfbVeNCryptTLSNone ||
            t==rfbVeNCryptTLSVNC ||
            t==rfbVeNCryptTLSPlain ||
            t==rfbVeNCryptX509None ||
            t==rfbVeNCryptX509VNC ||
            t==rfbVeNCryptX509Plain)
        {
            flag++;
            authScheme=t;
            rfbClientLog("Selecting security type %d (%d/%d in the list)\n", authScheme, loop, count);
            /* send back 4 bytes (in original byte order!) indicating which security type to use */
            if (!WriteToRFBServer(client, (char *)&tAuth[loop], 4)) return FALSE;
        }
        tAuth[loop]=t;
    }
    if (authScheme==0)
    {
        memset(buf1, 0, sizeof(buf1));
        for (loop=0;loop<count;loop++)
        {
            if (strlen(buf1)>=sizeof(buf1)-1) break;
            snprintf(buf2, sizeof(buf2), (loop>0 ? ", %d" : "%d"), (int)tAuth[loop]);
            strncat(buf1, buf2, sizeof(buf1)-strlen(buf1)-1);
        }
        rfbClientLog("Unknown VeNCrypt authentication scheme from VNC server: %s\n",
               buf1);
        return FALSE;
    }
    *result = authScheme;
    return TRUE;
}

rfbBool
HandleAnonTLSAuth(rfbClient* client)
{
  if (!InitializeTLS() || !InitializeTLSSession(client, TRUE)) return FALSE;

  if (!SetTLSAnonCredential(client)) return FALSE;

  if (!HandshakeTLS(client)) return FALSE;

  return TRUE;
}

rfbBool
HandleVeNCryptAuth(rfbClient* client)
{
  uint8_t major, minor, status;
  uint32_t authScheme;
  rfbBool anonTLS;
//  gnutls_certificate_credentials_t x509_cred = NULL;

  if (!InitializeTLS()) return FALSE;

  /* Read VeNCrypt version */
  if (!ReadFromRFBServer(client, (char *)&major, 1) ||
      !ReadFromRFBServer(client, (char *)&minor, 1))
  {
    return FALSE;
  }
  rfbClientLog("Got VeNCrypt version %d.%d from server.\n", (int)major, (int)minor);

  if (major != 0 && minor != 2)
  {
    rfbClientLog("Unsupported VeNCrypt version.\n");
    return FALSE;
  }

  if (!WriteToRFBServer(client, (char *)&major, 1) ||
      !WriteToRFBServer(client, (char *)&minor, 1) ||
      !ReadFromRFBServer(client, (char *)&status, 1))
  {
    return FALSE;
  }

  if (status != 0)
  {
    rfbClientLog("Server refused VeNCrypt version %d.%d.\n", (int)major, (int)minor);
    return FALSE;
  }

  if (!ReadVeNCryptSecurityType(client, &authScheme)) return FALSE;
  if (!ReadFromRFBServer(client, (char *)&status, 1) || status != 1)
  {
    rfbClientLog("Server refused VeNCrypt authentication %d (%d).\n", authScheme, (int)status);
    return FALSE;
  }
  client->subAuthScheme = authScheme;

  /* Some VeNCrypt security types are anonymous TLS, others are X509 */
  switch (authScheme)
  {
    case rfbVeNCryptTLSNone:
    case rfbVeNCryptTLSVNC:
    case rfbVeNCryptTLSPlain:
      anonTLS = TRUE;
      break;
    default:
      anonTLS = FALSE;
      break;
  }

  /* Get X509 Credentials if it's not anonymous */
  if (!anonTLS)
  {
    rfbCredential *cred;

    if (!client->GetCredential)
    {
      rfbClientLog("GetCredential callback is not set.\n");
      return FALSE;
    }
    cred = client->GetCredential(client, rfbCredentialTypeX509);
    if (!cred)
    {
      rfbClientLog("Reading credential failed\n");
      return FALSE;
    }

    /* TODO: don't just ignore this
    x509_cred = CreateX509CertCredential(cred);
    FreeX509Credential(cred);
    if (!x509_cred) return FALSE; */
  }

  /* Start up the TLS session */
  if (!InitializeTLSSession(client, anonTLS)) return FALSE;

  if (anonTLS)
  {
    if (!SetTLSAnonCredential(client)) return FALSE;
  }
  else
  {
/* TODO: don't just ignore this
     if ((ret = gnutls_credentials_set(client->tlsSession, GNUTLS_CRD_CERTIFICATE, x509_cred)) < 0)
     {
        rfbClientLog("Cannot set x509 credential: %s.\n", gnutls_strerror(ret));
        FreeTLS(client); */
      return FALSE;
      //  }  
  }

  if (!HandshakeTLS(client)) return FALSE;

  /* TODO: validate certificate */

  /* We are done here. The caller should continue with client->subAuthScheme
   * to do actual sub authentication.
   */
  return TRUE;
}

int
ReadFromTLS(rfbClient* client, char *out, unsigned int n)
{
  ssize_t ret;

  ret = SSL_read (client->tlsSession, out, n);

  if (ret >= 0)
    return ret;
  else {
    errno = ssl_errno (client->tlsSession, ret);

    if (errno != EAGAIN) {
      rfbClientLog("Error reading from TLS: -.\n");
    }
  }

  return -1;
}

int
WriteToTLS(rfbClient* client, char *buf, unsigned int n)
{
  unsigned int offset = 0;
  ssize_t ret;

  while (offset < n)
  {

    ret = SSL_write (client->tlsSession, buf + offset, (size_t)(n-offset));

    if (ret < 0)
      errno = ssl_errno (client->tlsSession, ret);

    if (ret == 0) continue;
    if (ret < 0)
    {
      if (errno == EAGAIN || errno == EWOULDBLOCK) continue;
      rfbClientLog("Error writing to TLS: -\n");
      return -1;
    }
    offset += (unsigned int)ret;
  }
  return offset;
}

void FreeTLS(rfbClient* client)
{
  int i;

  if (mutex_buf != NULL) {
    CRYPTO_set_dynlock_create_callback(NULL);
    CRYPTO_set_dynlock_lock_callback(NULL);
    CRYPTO_set_dynlock_destroy_callback(NULL);

    CRYPTO_set_locking_callback(NULL);
    CRYPTO_set_id_callback(NULL);

    for (i = 0; i < CRYPTO_num_locks(); i++)
      pthread_mutex_destroy(&mutex_buf[i]);
    free(mutex_buf);
    mutex_buf = NULL;
  }

  SSL_free(client->tlsSession);
}