D-Bus  1.7.6
dbus-nonce.c
1 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
2 /* dbus-nonce.c Nonce handling functions used by nonce-tcp (internal to D-Bus implementation)
3  *
4  * Copyright (C) 2009 Klaralvdalens Datakonsult AB, a KDAB Group company, info@kdab.net
5  *
6  * Licensed under the Academic Free License version 2.1
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License as published by
10  * the Free Software Foundation; either version 2 of the License, or
11  * (at your option) any later version.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public License
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21  *
22  */
23 
24 #include <config.h>
25 // major sections of this file are modified code from libassuan, (C) FSF
26 #include "dbus-nonce.h"
27 #include "dbus-internals.h"
28 #include "dbus-protocol.h"
29 #include "dbus-sysdeps.h"
30 
31 #include <stdio.h>
32 
33 static dbus_bool_t
34 do_check_nonce (int fd, const DBusString *nonce, DBusError *error)
35 {
36  DBusString buffer;
37  DBusString p;
38  size_t nleft;
39  dbus_bool_t result;
40  int n;
41 
42  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
43 
44  nleft = 16;
45 
46  if ( !_dbus_string_init (&buffer)
47  || !_dbus_string_init (&p) ) {
49  _dbus_string_free (&p);
50  _dbus_string_free (&buffer);
51  return FALSE;
52  }
53 
54  while (nleft)
55  {
56  n = _dbus_read_socket (fd, &p, nleft);
57  if (n == -1 && _dbus_get_is_errno_eintr())
58  ;
59  else if (n == -1 && _dbus_get_is_errno_eagain_or_ewouldblock())
61  else if (n==-1)
62  {
63  dbus_set_error (error, DBUS_ERROR_IO_ERROR, "Could not read nonce from socket (fd=%d)", fd );
64  _dbus_string_free (&p);
65  _dbus_string_free (&buffer);
66  return FALSE;
67  }
68  else if (!n)
69  {
70  _dbus_string_free (&p);
71  _dbus_string_free (&buffer);
72  dbus_set_error (error, DBUS_ERROR_IO_ERROR, "Could not read nonce from socket (fd=%d)", fd );
73  return FALSE;
74  }
75  else
76  {
77  _dbus_string_append_len(&buffer, _dbus_string_get_const_data (&p), n);
78  nleft -= n;
79  }
80  }
81 
82  result = _dbus_string_equal_len (&buffer, nonce, 16);
83  if (!result)
84  dbus_set_error (error, DBUS_ERROR_ACCESS_DENIED, "Nonces do not match, access denied (fd=%d)", fd );
85 
86  _dbus_string_free (&p);
87  _dbus_string_free (&buffer);
88 
89  return result;
90 }
91 
101 _dbus_read_nonce (const DBusString *fname, DBusString *nonce, DBusError* error)
102 {
103  FILE *fp;
104  char buffer[17];
105  size_t nread;
106 
107  buffer[sizeof buffer - 1] = '\0';
108 
109  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
110 
111  _dbus_verbose ("reading nonce from file: %s\n", _dbus_string_get_const_data (fname));
112 
113 
114  fp = fopen (_dbus_string_get_const_data (fname), "rb");
115  if (!fp)
116  return FALSE;
117  nread = fread (buffer, 1, sizeof buffer - 1, fp);
118  fclose (fp);
119  if (!nread)
120  {
121  dbus_set_error (error, DBUS_ERROR_FILE_NOT_FOUND, "Could not read nonce from file %s", _dbus_string_get_const_data (fname));
122  return FALSE;
123  }
124 
125  if (!_dbus_string_append_len (nonce, buffer, sizeof buffer - 1 ))
126  {
128  return FALSE;
129  }
130  return TRUE;
131 }
132 
133 int
134 _dbus_accept_with_noncefile (int listen_fd, const DBusNonceFile *noncefile)
135 {
136  int fd;
137  DBusString nonce;
138 
139  _dbus_assert (noncefile != NULL);
140  if (!_dbus_string_init (&nonce))
141  return -1;
142  //PENDING(kdab): set better errors
143  if (_dbus_read_nonce (_dbus_noncefile_get_path(noncefile), &nonce, NULL) != TRUE)
144  return -1;
145  fd = _dbus_accept (listen_fd);
146  if (_dbus_socket_is_invalid (fd))
147  return fd;
148  if (do_check_nonce(fd, &nonce, NULL) != TRUE) {
149  _dbus_verbose ("nonce check failed. Closing socket.\n");
151  return -1;
152  }
153 
154  return fd;
155 }
156 
157 static dbus_bool_t
158 generate_and_write_nonce (const DBusString *filename, DBusError *error)
159 {
160  DBusString nonce;
161  dbus_bool_t ret;
162 
163  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
164 
165  if (!_dbus_string_init (&nonce))
166  {
168  return FALSE;
169  }
170 
171  if (!_dbus_generate_random_bytes (&nonce, 16))
172  {
174  _dbus_string_free (&nonce);
175  return FALSE;
176  }
177 
178  ret = _dbus_string_save_to_file (&nonce, filename, FALSE, error);
179 
180  _dbus_string_free (&nonce);
181 
182  return ret;
183 }
184 
195 _dbus_send_nonce (int fd, const DBusString *noncefile, DBusError *error)
196 {
197  dbus_bool_t read_result;
198  int send_result;
199  DBusString nonce;
200 
201  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
202 
203  if (_dbus_string_get_length (noncefile) == 0)
204  return FALSE;
205 
206  if (!_dbus_string_init (&nonce))
207  {
209  return FALSE;
210  }
211 
212  read_result = _dbus_read_nonce (noncefile, &nonce, error);
213  if (!read_result)
214  {
215  _DBUS_ASSERT_ERROR_IS_SET (error);
216  _dbus_string_free (&nonce);
217  return FALSE;
218  }
219  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
220 
221  send_result = _dbus_write_socket (fd, &nonce, 0, _dbus_string_get_length (&nonce));
222 
223  _dbus_string_free (&nonce);
224 
225  if (send_result == -1)
226  {
227  dbus_set_error (error,
229  "Failed to send nonce (fd=%d): %s",
231  return FALSE;
232  }
233 
234  return TRUE;
235 }
236 
237 static dbus_bool_t
238 do_noncefile_create (DBusNonceFile *noncefile,
239  DBusError *error,
240  dbus_bool_t use_subdir)
241 {
242  DBusString randomStr;
243  const char *tmp;
244 
245  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
246 
247  _dbus_assert (noncefile);
248 
249  if (!_dbus_string_init (&randomStr))
250  {
252  goto on_error;
253  }
254 
255  if (!_dbus_generate_random_ascii (&randomStr, 8))
256  {
258  goto on_error;
259  }
260 
261  tmp = _dbus_get_tmpdir ();
262 
263  if (!_dbus_string_init (&noncefile->dir)
264  || tmp == NULL
265  || !_dbus_string_append (&noncefile->dir, tmp))
266  {
268  goto on_error;
269  }
270  if (use_subdir)
271  {
272  if (!_dbus_string_append (&noncefile->dir, "/dbus_nonce-")
273  || !_dbus_string_append (&noncefile->dir, _dbus_string_get_const_data (&randomStr)) )
274  {
276  goto on_error;
277  }
278  if (!_dbus_string_init (&noncefile->path)
279  || !_dbus_string_copy (&noncefile->dir, 0, &noncefile->path, 0)
280  || !_dbus_string_append (&noncefile->path, "/nonce"))
281  {
283  goto on_error;
284  }
285  if (!_dbus_create_directory (&noncefile->dir, error))
286  {
287  _DBUS_ASSERT_ERROR_IS_SET (error);
288  goto on_error;
289  }
290  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
291 
292  }
293  else
294  {
295  if (!_dbus_string_init (&noncefile->path)
296  || !_dbus_string_copy (&noncefile->dir, 0, &noncefile->path, 0)
297  || !_dbus_string_append (&noncefile->path, "/dbus_nonce-")
298  || !_dbus_string_append (&noncefile->path, _dbus_string_get_const_data (&randomStr)))
299  {
301  goto on_error;
302  }
303 
304  }
305 
306  if (!generate_and_write_nonce (&noncefile->path, error))
307  {
308  _DBUS_ASSERT_ERROR_IS_SET (error);
309  if (use_subdir)
310  _dbus_delete_directory (&noncefile->dir, NULL); //we ignore possible errors deleting the dir and return the write error instead
311  goto on_error;
312  }
313  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
314 
315  _dbus_string_free (&randomStr);
316 
317  return TRUE;
318  on_error:
319  if (use_subdir)
320  _dbus_delete_directory (&noncefile->dir, NULL);
321  _dbus_string_free (&noncefile->dir);
322  _dbus_string_free (&noncefile->path);
323  _dbus_string_free (&randomStr);
324  return FALSE;
325 }
326 
327 #ifdef DBUS_WIN
328 
336 _dbus_noncefile_create (DBusNonceFile *noncefile,
337  DBusError *error)
338 {
339  return do_noncefile_create (noncefile, error, /*use_subdir=*/FALSE);
340 }
341 
350 _dbus_noncefile_delete (DBusNonceFile *noncefile,
351  DBusError *error)
352 {
353  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
354 
355  _dbus_delete_file (&noncefile->path, error);
356  _dbus_string_free (&noncefile->dir);
357  _dbus_string_free (&noncefile->path);
358  return TRUE;
359 }
360 
361 #else
362 
371 _dbus_noncefile_create (DBusNonceFile *noncefile,
372  DBusError *error)
373 {
374  return do_noncefile_create (noncefile, error, /*use_subdir=*/TRUE);
375 }
376 
385 _dbus_noncefile_delete (DBusNonceFile *noncefile,
386  DBusError *error)
387 {
388  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
389 
390  _dbus_delete_directory (&noncefile->dir, error);
391  _dbus_string_free (&noncefile->dir);
392  _dbus_string_free (&noncefile->path);
393  return TRUE;
394 }
395 #endif
396 
397 
404 const DBusString*
405 _dbus_noncefile_get_path (const DBusNonceFile *noncefile)
406 {
407  _dbus_assert (noncefile);
408  return &noncefile->path;
409 }
410 
422 _dbus_noncefile_check_nonce (int fd,
423  const DBusNonceFile *noncefile,
424  DBusError* error)
425 {
426  return do_check_nonce (fd, _dbus_noncefile_get_path (noncefile), error);
427 }
428 
429