D-Bus 1.16.0

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 * SPDX-License-Identifier: AFL-2.1 OR GPL-2.0-or-later
7 *
8 * Licensed under the Academic Free License version 2.1
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 *
24 */
25
26#include <config.h>
27// major sections of this file are modified code from libassuan, (C) FSF
28#include "dbus-nonce.h"
29#include "dbus-internals.h"
30#include "dbus-protocol.h"
31#include "dbus-sysdeps.h"
32
33#include <stdio.h>
34
35 struct DBusNonceFile
36{
37 DBusString path;
38 DBusString dir;
39};
40
41 static dbus_bool_t
42do_check_nonce (DBusSocket fd, const DBusString *nonce, DBusError *error)
43{
44 DBusString buffer;
45 DBusString p;
46 size_t nleft;
47 dbus_bool_t result;
48 int n;
49
50 _DBUS_ASSERT_ERROR_IS_CLEAR (error);
51
52 nleft = 16;
53
54 /* This is a trick to make it safe to call _dbus_string_free on these
55 * strings during error unwinding, even if allocating memory for them
56 * fails. A constant DBusString is considered to be valid to "free",
57 * even though there is nothing to free (of course the free operation
58 * is trivial, because it does not own its own buffer); but
59 * unlike a mutable DBusString, initializing a constant DBusString
60 * cannot fail.
61 *
62 * We must successfully re-initialize the strings to be mutable before
63 * writing to them, of course.
64 */
65 _dbus_string_init_const (&buffer, "");
66 _dbus_string_init_const (&p, "");
67
68 if ( !_dbus_string_init (&buffer)
69 || !_dbus_string_init (&p) ) {
70 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
71 _dbus_string_free (&p);
72 _dbus_string_free (&buffer);
73 return FALSE;
74 }
75
76 while (nleft)
77 {
78 int saved_errno;
79
80 n = _dbus_read_socket (fd, &p, nleft);
81 saved_errno = _dbus_save_socket_errno ();
82
83 if (n == -1 && _dbus_get_is_errno_eintr (saved_errno))
84 ;
85 else if (n == -1 && _dbus_get_is_errno_eagain_or_ewouldblock (saved_errno))
86 _dbus_sleep_milliseconds (100);
87 else if (n==-1)
88 {
89 dbus_set_error (error, DBUS_ERROR_IO_ERROR, "Could not read nonce from socket (fd=%" DBUS_SOCKET_FORMAT ")", _dbus_socket_printable (fd));
90 _dbus_string_free (&p);
91 _dbus_string_free (&buffer);
92 return FALSE;
93 }
94 else if (!n)
95 {
96 _dbus_string_free (&p);
97 _dbus_string_free (&buffer);
98 dbus_set_error (error, DBUS_ERROR_IO_ERROR, "Could not read nonce from socket (fd=%" DBUS_SOCKET_FORMAT ")", _dbus_socket_printable (fd));
99 return FALSE;
100 }
101 else
102 {
103 if (!_dbus_string_append_len (&buffer, _dbus_string_get_const_data (&p), n))
104 {
105 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
106 _dbus_string_free (&p);
107 _dbus_string_free (&buffer);
108 return FALSE;
109 }
110 nleft -= n;
111 }
112 }
113
114 result = _dbus_string_equal_len (&buffer, nonce, 16);
115 if (!result)
116 dbus_set_error (error, DBUS_ERROR_ACCESS_DENIED, "Nonces do not match, access denied (fd=%" DBUS_SOCKET_FORMAT ")", _dbus_socket_printable (fd));
117
118 _dbus_string_free (&p);
119 _dbus_string_free (&buffer);
120
121 return result;
122}
123
132 dbus_bool_t
133_dbus_read_nonce (const DBusString *fname, DBusString *nonce, DBusError* error)
134{
135 FILE *fp;
136 char buffer[17];
137 size_t nread;
138
139 buffer[sizeof buffer - 1] = '\0';
140
141 _DBUS_ASSERT_ERROR_IS_CLEAR (error);
142
143 _dbus_verbose ("reading nonce from file: %s\n", _dbus_string_get_const_data (fname));
144
145
146 fp = fopen (_dbus_string_get_const_data (fname), "rb");
147 if (!fp)
148 {
149 dbus_set_error (error,
150 _dbus_error_from_system_errno (),
151 "Failed to open %s for read: %s",
152 _dbus_string_get_const_data (fname),
153 _dbus_strerror_from_errno ());
154 return FALSE;
155 }
156
157 nread = fread (buffer, 1, sizeof buffer - 1, fp);
158 fclose (fp);
159 if (!nread)
160 {
161 dbus_set_error (error, DBUS_ERROR_FILE_NOT_FOUND, "Could not read nonce from file %s", _dbus_string_get_const_data (fname));
162 return FALSE;
163 }
164
165 if (!_dbus_string_append_len (nonce, buffer, sizeof buffer - 1 ))
166 {
167 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
168 return FALSE;
169 }
170 return TRUE;
171}
172
173 DBusSocket
174_dbus_accept_with_noncefile (DBusSocket listen_fd, const DBusNonceFile *noncefile)
175{
176 DBusSocket fd = _dbus_socket_get_invalid ();
177 DBusString nonce;
178
179 _dbus_assert (noncefile != NULL);
180
181 /* Make it valid to "free" this even if _dbus_string_init() runs
182 * out of memory: see comment in do_check_nonce() */
183 _dbus_string_init_const (&nonce, "");
184
185 if (!_dbus_string_init (&nonce))
186 goto out;
187
188 //PENDING(kdab): set better errors
189 if (_dbus_read_nonce (_dbus_noncefile_get_path(noncefile), &nonce, NULL) != TRUE)
190 goto out;
191
192 fd = _dbus_accept (listen_fd);
193
194 if (!_dbus_socket_is_valid (fd))
195 goto out;
196
197 if (do_check_nonce(fd, &nonce, NULL) != TRUE) {
198 _dbus_verbose ("nonce check failed. Closing socket.\n");
199 _dbus_close_socket (&fd, NULL);
200 goto out;
201 }
202
203out:
204 _dbus_string_free (&nonce);
205 return fd;
206}
207
208 static dbus_bool_t
209generate_and_write_nonce (const DBusString *filename, DBusError *error)
210{
211 DBusString nonce;
212 dbus_bool_t ret;
213
214 _DBUS_ASSERT_ERROR_IS_CLEAR (error);
215
216 if (!_dbus_string_init (&nonce))
217 {
218 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
219 return FALSE;
220 }
221
222 if (!_dbus_generate_random_bytes (&nonce, 16, error))
223 {
224 _dbus_string_free (&nonce);
225 return FALSE;
226 }
227
228 ret = _dbus_string_save_to_file (&nonce, filename, FALSE, error);
229
230 _dbus_string_free (&nonce);
231
232 return ret;
233}
234
244 dbus_bool_t
245_dbus_send_nonce (DBusSocket fd,
246 const DBusString *noncefile,
247 DBusError *error)
248{
249 dbus_bool_t read_result;
250 int send_result;
251 DBusString nonce;
252
253 _DBUS_ASSERT_ERROR_IS_CLEAR (error);
254
255 if (_dbus_string_get_length (noncefile) == 0)
256 return FALSE;
257
258 if (!_dbus_string_init (&nonce))
259 {
260 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
261 return FALSE;
262 }
263
264 read_result = _dbus_read_nonce (noncefile, &nonce, error);
265 if (!read_result)
266 {
267 _DBUS_ASSERT_ERROR_IS_SET (error);
268 _dbus_string_free (&nonce);
269 return FALSE;
270 }
271 _DBUS_ASSERT_ERROR_IS_CLEAR (error);
272
273 send_result = _dbus_write_socket (fd, &nonce, 0, _dbus_string_get_length (&nonce));
274
275 _dbus_string_free (&nonce);
276
277 if (send_result == -1)
278 {
279 dbus_set_error (error,
280 _dbus_error_from_system_errno (),
281 "Failed to send nonce (fd=%" DBUS_SOCKET_FORMAT "): %s",
282 _dbus_socket_printable (fd),
283 _dbus_strerror_from_errno ());
284 return FALSE;
285 }
286
287 return TRUE;
288}
289
290 static dbus_bool_t
291do_noncefile_create (DBusNonceFile **noncefile_out,
292 DBusError *error,
293 dbus_bool_t use_subdir)
294{
295 DBusNonceFile *noncefile = NULL;
296 DBusString randomStr;
297 const char *tmp;
298
299 _DBUS_ASSERT_ERROR_IS_CLEAR (error);
300
301 _dbus_assert (noncefile_out != NULL);
302 _dbus_assert (*noncefile_out == NULL);
303
304 noncefile = dbus_new0 (DBusNonceFile, 1);
305 if (noncefile == NULL)
306 {
307 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
308 return FALSE;
309 }
310
311 /* Make it valid to "free" these even if _dbus_string_init() runs
312 * out of memory: see comment in do_check_nonce() */
313 _dbus_string_init_const (&randomStr, "");
314 _dbus_string_init_const (&noncefile->dir, "");
315 _dbus_string_init_const (&noncefile->path, "");
316
317 if (!_dbus_string_init (&randomStr))
318 {
319 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
320 goto on_error;
321 }
322
323 if (!_dbus_generate_random_ascii (&randomStr, 8, error))
324 {
325 goto on_error;
326 }
327
328 tmp = _dbus_get_tmpdir ();
329
330 if (!_dbus_string_init (&noncefile->dir)
331 || tmp == NULL
332 || !_dbus_string_append (&noncefile->dir, tmp))
333 {
334 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
335 goto on_error;
336 }
337 if (use_subdir)
338 {
339 if (!_dbus_string_append (&noncefile->dir, "/dbus_nonce-")
340 || !_dbus_string_append (&noncefile->dir, _dbus_string_get_const_data (&randomStr)) )
341 {
342 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
343 goto on_error;
344 }
345 if (!_dbus_string_init (&noncefile->path)
346 || !_dbus_string_copy (&noncefile->dir, 0, &noncefile->path, 0)
347 || !_dbus_string_append (&noncefile->path, "/nonce"))
348 {
349 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
350 goto on_error;
351 }
352 if (!_dbus_create_directory (&noncefile->dir, error))
353 {
354 _DBUS_ASSERT_ERROR_IS_SET (error);
355 goto on_error;
356 }
357 _DBUS_ASSERT_ERROR_IS_CLEAR (error);
358
359 }
360 else
361 {
362 if (!_dbus_string_init (&noncefile->path)
363 || !_dbus_string_copy (&noncefile->dir, 0, &noncefile->path, 0)
364 || !_dbus_string_append (&noncefile->path, "/dbus_nonce-")
365 || !_dbus_string_append (&noncefile->path, _dbus_string_get_const_data (&randomStr)))
366 {
367 dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
368 goto on_error;
369 }
370
371 }
372
373 if (!generate_and_write_nonce (&noncefile->path, error))
374 {
375 _DBUS_ASSERT_ERROR_IS_SET (error);
376 if (use_subdir)
377 _dbus_delete_directory (&noncefile->dir, NULL); //we ignore possible errors deleting the dir and return the write error instead
378 goto on_error;
379 }
380 _DBUS_ASSERT_ERROR_IS_CLEAR (error);
381
382 *noncefile_out = noncefile;
383 _dbus_string_free (&randomStr);
384
385 return TRUE;
386 on_error:
387 if (use_subdir && _dbus_string_get_length (&noncefile->dir) != 0)
388 _dbus_delete_directory (&noncefile->dir, NULL);
389 _dbus_string_free (&noncefile->dir);
390 _dbus_string_free (&noncefile->path);
391 dbus_free (noncefile);
392 _dbus_string_free (&randomStr);
393 return FALSE;
394}
395
396#ifdef DBUS_WIN
404 dbus_bool_t
405_dbus_noncefile_create (DBusNonceFile **noncefile_out,
406 DBusError *error)
407{
408 return do_noncefile_create (noncefile_out, error, /*use_subdir=*/FALSE);
409}
410
421 dbus_bool_t
422_dbus_noncefile_delete (DBusNonceFile **noncefile_location,
423 DBusError *error)
424{
425 DBusNonceFile *noncefile;
426
427 _DBUS_ASSERT_ERROR_IS_CLEAR (error);
428 _dbus_assert (noncefile_location != NULL);
429
430 noncefile = *noncefile_location;
431 *noncefile_location = NULL;
432
433 if (noncefile == NULL)
434 {
435 /* Nothing to do */
436 return TRUE;
437 }
438
439 _dbus_delete_file (&noncefile->path, error);
440 _dbus_string_free (&noncefile->dir);
441 _dbus_string_free (&noncefile->path);
442 dbus_free (noncefile);
443 return TRUE;
444}
445
446#else
455 dbus_bool_t
456_dbus_noncefile_create (DBusNonceFile **noncefile_out,
457 DBusError *error)
458{
459 return do_noncefile_create (noncefile_out, error, /*use_subdir=*/TRUE);
460}
461
472 dbus_bool_t
473_dbus_noncefile_delete (DBusNonceFile **noncefile_location,
474 DBusError *error)
475{
476 DBusNonceFile *noncefile;
477
478 _DBUS_ASSERT_ERROR_IS_CLEAR (error);
479 _dbus_assert (noncefile_location != NULL);
480
481 noncefile = *noncefile_location;
482 *noncefile_location = NULL;
483
484 if (noncefile == NULL)
485 {
486 /* Nothing to do */
487 return TRUE;
488 }
489
490 _dbus_delete_directory (&noncefile->dir, error);
491 _dbus_string_free (&noncefile->dir);
492 _dbus_string_free (&noncefile->path);
493 dbus_free (noncefile);
494 return TRUE;
495}
496#endif
497
498
505 const DBusString*
506_dbus_noncefile_get_path (const DBusNonceFile *noncefile)
507{
508 _dbus_assert (noncefile);
509 return &noncefile->path;
510}
511
522 dbus_bool_t
523_dbus_noncefile_check_nonce (DBusSocket fd,
524 const DBusNonceFile *noncefile,
525 DBusError* error)
526{
527 return do_check_nonce (fd, _dbus_noncefile_get_path (noncefile), error);
528}
529
530
dbus_set_error
void dbus_set_error(DBusError *error, const char *name, const char *format,...)
Assigns an error name and message to a DBusError.
Definition dbus-errors.c:356
_dbus_delete_file
dbus_bool_t _dbus_delete_file(const DBusString *filename, DBusError *error)
Deletes the given file.
Definition dbus-file-unix.c:441
_dbus_string_save_to_file
dbus_bool_t _dbus_string_save_to_file(const DBusString *str, const DBusString *filename, dbus_bool_t world_readable, DBusError *error)
Writes a string out to a file.
Definition dbus-file-unix.c:208
_dbus_assert
#define _dbus_assert(condition)
Aborts with an error message if the condition is false.
Definition dbus-internals.h:153
_dbus_generate_random_ascii
dbus_bool_t _dbus_generate_random_ascii(DBusString *str, int n_bytes, DBusError *error)
Generates the given number of random bytes, where the bytes are chosen from the alphanumeric ASCII su...
Definition dbus-sysdeps.c:525
_dbus_error_from_system_errno
const char * _dbus_error_from_system_errno(void)
Converts the current system errno value into a DBusError name.
Definition dbus-sysdeps.c:657
_dbus_strerror_from_errno
const char * _dbus_strerror_from_errno(void)
Get error message from errno.
Definition dbus-sysdeps.c:724
_dbus_get_is_errno_eintr
dbus_bool_t _dbus_get_is_errno_eintr(int e)
See if errno is EINTR.
Definition dbus-sysdeps.c:690
NULL
#define NULL
A null pointer, defined appropriately for C or C++.
Definition dbus-macros.h:51
TRUE
#define TRUE
Expands to "1".
Definition dbus-macros.h:41
FALSE
#define FALSE
Expands to "0".
Definition dbus-macros.h:44
dbus_free
void dbus_free(void *memory)
Frees a block of memory previously allocated by dbus_malloc() or dbus_malloc0().
Definition dbus-memory.c:710
dbus_new0
#define dbus_new0(type, count)
Safe macro for using dbus_malloc0().
Definition dbus-memory.h:60
DBUS_ERROR_IO_ERROR
#define DBUS_ERROR_IO_ERROR
Something went wrong reading or writing to a socket, for example.
Definition dbus-protocol.h:371
DBUS_ERROR_ACCESS_DENIED
#define DBUS_ERROR_ACCESS_DENIED
Security restrictions don't allow doing what you're trying to do.
Definition dbus-protocol.h:379
DBUS_ERROR_NO_MEMORY
#define DBUS_ERROR_NO_MEMORY
There was not enough memory to complete an operation.
Definition dbus-protocol.h:363
DBUS_ERROR_FILE_NOT_FOUND
#define DBUS_ERROR_FILE_NOT_FOUND
Missing file.
Definition dbus-protocol.h:399
_dbus_string_append
dbus_bool_t _dbus_string_append(DBusString *str, const char *buffer)
Appends a nul-terminated C-style string to a DBusString.
Definition dbus-string.c:980
_dbus_string_init
dbus_bool_t _dbus_string_init(DBusString *str)
Initializes a string.
Definition dbus-string.c:182
_dbus_string_init_const
void _dbus_string_init_const(DBusString *str, const char *value)
Initializes a constant string.
Definition dbus-string.c:197
_dbus_string_copy
dbus_bool_t _dbus_string_copy(const DBusString *source, int start, DBusString *dest, int insert_at)
Like _dbus_string_move(), but does not delete the section of the source string that's copied to the d...
Definition dbus-string.c:1345
_dbus_string_append_len
dbus_bool_t _dbus_string_append_len(DBusString *str, const char *buffer, int len)
Appends block of bytes with the given length to a DBusString.
Definition dbus-string.c:1170
_dbus_string_free
void _dbus_string_free(DBusString *str)
Frees a string created by _dbus_string_init(), and fills it with the same contents as _DBUS_STRING_IN...
Definition dbus-string.c:278
_dbus_string_equal_len
dbus_bool_t _dbus_string_equal_len(const DBusString *a, const DBusString *b, int len)
Tests two DBusString for equality up to the given length.
Definition dbus-string.c:2118
_dbus_get_is_errno_eagain_or_ewouldblock
dbus_bool_t _dbus_get_is_errno_eagain_or_ewouldblock(int e)
See if errno is EAGAIN or EWOULDBLOCK (this has to be done differently for Winsock so is abstracted)
Definition dbus-sysdeps-unix.c:4801
_dbus_read_socket
int _dbus_read_socket(DBusSocket fd, DBusString *buffer, int count)
Like _dbus_read(), but only works on sockets so is available on Windows.
Definition dbus-sysdeps-unix.c:338
_dbus_write_socket
int _dbus_write_socket(DBusSocket fd, const DBusString *buffer, int start, int len)
Like _dbus_write(), but only supports sockets and is thus available on Windows.
Definition dbus-sysdeps-unix.c:356
_dbus_sleep_milliseconds
void _dbus_sleep_milliseconds(int milliseconds)
Sleeps the given number of milliseconds.
Definition dbus-sysdeps-unix.c:3542
_dbus_close_socket
dbus_bool_t _dbus_close_socket(DBusSocket *fd, DBusError *error)
Closes a socket and invalidates it.
Definition dbus-sysdeps-unix.c:314
_dbus_generate_random_bytes
dbus_bool_t _dbus_generate_random_bytes(DBusString *str, int n_bytes, DBusError *error)
Generates the given number of securely random bytes, using the best mechanism we can come up with.
Definition dbus-sysdeps-unix.c:3572
_dbus_delete_directory
dbus_bool_t _dbus_delete_directory(const DBusString *filename, DBusError *error)
Removes a directory; Directory must be empty.
Definition dbus-sysdeps-unix.c:4822
_dbus_accept
DBusSocket _dbus_accept(DBusSocket listen_fd)
Accepts a connection on a listening socket.
Definition dbus-sysdeps-unix.c:2589
_dbus_get_tmpdir
const char * _dbus_get_tmpdir(void)
Gets the temporary files directory by inspecting the environment variables TMPDIR,...
Definition dbus-sysdeps-unix.c:4029
_dbus_create_directory
dbus_bool_t _dbus_create_directory(const DBusString *filename, DBusError *error)
Creates a directory.
Definition dbus-sysdeps-unix.c:3466
dbus_bool_t
dbus_uint32_t dbus_bool_t
A boolean, valid values are TRUE and FALSE.
Definition dbus-types.h:37
DBusError
Object representing an exception.
Definition dbus-errors.h:51
DBusNonceFile
Definition dbus-nonce.c:36
DBusSocket
Socket interface.
Definition dbus-sysdeps.h:185
DBusString
Definition dbus-string.h:47