D-Bus  1.8.2
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) ) {
48  dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
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())
60  _dbus_sleep_milliseconds (100);
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 
100 dbus_bool_t
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  {
117  dbus_set_error (error,
118  _dbus_error_from_system_errno (),
119  "Failed to open %s for read: %s",
120  _dbus_string_get_const_data (fname),
121  _dbus_strerror_from_errno ());
122  return FALSE;
123  }
124 
125  nread = fread (buffer, 1, sizeof buffer - 1, fp);
126  fclose (fp);
127  if (!nread)
128  {
129  dbus_set_error (error, DBUS_ERROR_FILE_NOT_FOUND, "Could not read nonce from file %s", _dbus_string_get_const_data (fname));
130  return FALSE;
131  }
132 
133  if (!_dbus_string_append_len (nonce, buffer, sizeof buffer - 1 ))
134  {
135  dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
136  return FALSE;
137  }
138  return TRUE;
139 }
140 
141 int
142 _dbus_accept_with_noncefile (int listen_fd, const DBusNonceFile *noncefile)
143 {
144  int fd;
145  DBusString nonce;
146 
147  _dbus_assert (noncefile != NULL);
148  if (!_dbus_string_init (&nonce))
149  return -1;
150  //PENDING(kdab): set better errors
151  if (_dbus_read_nonce (_dbus_noncefile_get_path(noncefile), &nonce, NULL) != TRUE)
152  return -1;
153  fd = _dbus_accept (listen_fd);
154  if (_dbus_socket_is_invalid (fd))
155  return fd;
156  if (do_check_nonce(fd, &nonce, NULL) != TRUE) {
157  _dbus_verbose ("nonce check failed. Closing socket.\n");
158  _dbus_close_socket(fd, NULL);
159  return -1;
160  }
161 
162  return fd;
163 }
164 
165 static dbus_bool_t
166 generate_and_write_nonce (const DBusString *filename, DBusError *error)
167 {
168  DBusString nonce;
169  dbus_bool_t ret;
170 
171  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
172 
173  if (!_dbus_string_init (&nonce))
174  {
175  dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
176  return FALSE;
177  }
178 
179  if (!_dbus_generate_random_bytes (&nonce, 16))
180  {
181  dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
182  _dbus_string_free (&nonce);
183  return FALSE;
184  }
185 
186  ret = _dbus_string_save_to_file (&nonce, filename, FALSE, error);
187 
188  _dbus_string_free (&nonce);
189 
190  return ret;
191 }
192 
202 dbus_bool_t
203 _dbus_send_nonce (int fd, const DBusString *noncefile, DBusError *error)
204 {
205  dbus_bool_t read_result;
206  int send_result;
207  DBusString nonce;
208 
209  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
210 
211  if (_dbus_string_get_length (noncefile) == 0)
212  return FALSE;
213 
214  if (!_dbus_string_init (&nonce))
215  {
216  dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
217  return FALSE;
218  }
219 
220  read_result = _dbus_read_nonce (noncefile, &nonce, error);
221  if (!read_result)
222  {
223  _DBUS_ASSERT_ERROR_IS_SET (error);
224  _dbus_string_free (&nonce);
225  return FALSE;
226  }
227  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
228 
229  send_result = _dbus_write_socket (fd, &nonce, 0, _dbus_string_get_length (&nonce));
230 
231  _dbus_string_free (&nonce);
232 
233  if (send_result == -1)
234  {
235  dbus_set_error (error,
236  _dbus_error_from_system_errno (),
237  "Failed to send nonce (fd=%d): %s",
238  fd, _dbus_strerror_from_errno ());
239  return FALSE;
240  }
241 
242  return TRUE;
243 }
244 
245 static dbus_bool_t
246 do_noncefile_create (DBusNonceFile *noncefile,
247  DBusError *error,
248  dbus_bool_t use_subdir)
249 {
250  DBusString randomStr;
251  const char *tmp;
252 
253  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
254 
255  _dbus_assert (noncefile);
256 
257  if (!_dbus_string_init (&randomStr))
258  {
259  dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
260  goto on_error;
261  }
262 
263  if (!_dbus_generate_random_ascii (&randomStr, 8))
264  {
265  dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
266  goto on_error;
267  }
268 
269  tmp = _dbus_get_tmpdir ();
270 
271  if (!_dbus_string_init (&noncefile->dir)
272  || tmp == NULL
273  || !_dbus_string_append (&noncefile->dir, tmp))
274  {
275  dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
276  goto on_error;
277  }
278  if (use_subdir)
279  {
280  if (!_dbus_string_append (&noncefile->dir, "/dbus_nonce-")
281  || !_dbus_string_append (&noncefile->dir, _dbus_string_get_const_data (&randomStr)) )
282  {
283  dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
284  goto on_error;
285  }
286  if (!_dbus_string_init (&noncefile->path)
287  || !_dbus_string_copy (&noncefile->dir, 0, &noncefile->path, 0)
288  || !_dbus_string_append (&noncefile->path, "/nonce"))
289  {
290  dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
291  goto on_error;
292  }
293  if (!_dbus_create_directory (&noncefile->dir, error))
294  {
295  _DBUS_ASSERT_ERROR_IS_SET (error);
296  goto on_error;
297  }
298  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
299 
300  }
301  else
302  {
303  if (!_dbus_string_init (&noncefile->path)
304  || !_dbus_string_copy (&noncefile->dir, 0, &noncefile->path, 0)
305  || !_dbus_string_append (&noncefile->path, "/dbus_nonce-")
306  || !_dbus_string_append (&noncefile->path, _dbus_string_get_const_data (&randomStr)))
307  {
308  dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
309  goto on_error;
310  }
311 
312  }
313 
314  if (!generate_and_write_nonce (&noncefile->path, error))
315  {
316  _DBUS_ASSERT_ERROR_IS_SET (error);
317  if (use_subdir)
318  _dbus_delete_directory (&noncefile->dir, NULL); //we ignore possible errors deleting the dir and return the write error instead
319  goto on_error;
320  }
321  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
322 
323  _dbus_string_free (&randomStr);
324 
325  return TRUE;
326  on_error:
327  if (use_subdir)
328  _dbus_delete_directory (&noncefile->dir, NULL);
329  _dbus_string_free (&noncefile->dir);
330  _dbus_string_free (&noncefile->path);
331  _dbus_string_free (&randomStr);
332  return FALSE;
333 }
334 
335 #ifdef DBUS_WIN
336 
343 dbus_bool_t
344 _dbus_noncefile_create (DBusNonceFile *noncefile,
345  DBusError *error)
346 {
347  return do_noncefile_create (noncefile, error, /*use_subdir=*/FALSE);
348 }
349 
357 dbus_bool_t
358 _dbus_noncefile_delete (DBusNonceFile *noncefile,
359  DBusError *error)
360 {
361  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
362 
363  _dbus_delete_file (&noncefile->path, error);
364  _dbus_string_free (&noncefile->dir);
365  _dbus_string_free (&noncefile->path);
366  return TRUE;
367 }
368 
369 #else
370 
378 dbus_bool_t
379 _dbus_noncefile_create (DBusNonceFile *noncefile,
380  DBusError *error)
381 {
382  return do_noncefile_create (noncefile, error, /*use_subdir=*/TRUE);
383 }
384 
392 dbus_bool_t
393 _dbus_noncefile_delete (DBusNonceFile *noncefile,
394  DBusError *error)
395 {
396  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
397 
398  _dbus_delete_directory (&noncefile->dir, error);
399  _dbus_string_free (&noncefile->dir);
400  _dbus_string_free (&noncefile->path);
401  return TRUE;
402 }
403 #endif
404 
405 
412 const DBusString*
413 _dbus_noncefile_get_path (const DBusNonceFile *noncefile)
414 {
415  _dbus_assert (noncefile);
416  return &noncefile->path;
417 }
418 
429 dbus_bool_t
430 _dbus_noncefile_check_nonce (int fd,
431  const DBusNonceFile *noncefile,
432  DBusError* error)
433 {
434  return do_check_nonce (fd, _dbus_noncefile_get_path (noncefile), error);
435 }
436 
437 
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