dbus-nonce.c
/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/* dbus-nonce.c Nonce handling functions used by nonce-tcp (internal to D-Bus implementation)
*
* Copyright (C) 2009 Klaralvdalens Datakonsult AB, a KDAB Group company, info@kdab.net
*
* Licensed under the Academic Free License version 2.1
*
* This program 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 program 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 program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <config.h>
// major sections of this file are modified code from libassuan, (C) FSF
#include "dbus-nonce.h"
#include "dbus-internals.h"
#include "dbus-protocol.h"
#include "dbus-sysdeps.h"
#include <stdio.h>
static dbus_bool_t
do_check_nonce (int fd, const DBusString *nonce, DBusError *error)
{
DBusString buffer;
DBusString p;
size_t nleft;
dbus_bool_t result;
int n;
_DBUS_ASSERT_ERROR_IS_CLEAR (error);
nleft = 16;
if ( !_dbus_string_init (&buffer)
|| !_dbus_string_init (&p) ) {
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
_dbus_string_free (&p);
_dbus_string_free (&buffer);
return FALSE;
}
while (nleft)
{
n = _dbus_read_socket (fd, &p, nleft);
if (n == -1 && _dbus_get_is_errno_eintr())
;
else if (n == -1 && _dbus_get_is_errno_eagain_or_ewouldblock())
_dbus_sleep_milliseconds (100);
else if (n==-1)
{
dbus_set_error (error, DBUS_ERROR_IO_ERROR, "Could not read nonce from socket (fd=%d)", fd );
_dbus_string_free (&p);
_dbus_string_free (&buffer);
return FALSE;
}
else if (!n)
{
_dbus_string_free (&p);
_dbus_string_free (&buffer);
dbus_set_error (error, DBUS_ERROR_IO_ERROR, "Could not read nonce from socket (fd=%d)", fd );
return FALSE;
}
else
{
_dbus_string_append_len(&buffer, _dbus_string_get_const_data (&p), n);
nleft -= n;
}
}
result = _dbus_string_equal_len (&buffer, nonce, 16);
if (!result)
dbus_set_error (error, DBUS_ERROR_ACCESS_DENIED, "Nonces do not match, access denied (fd=%d)", fd );
_dbus_string_free (&p);
_dbus_string_free (&buffer);
return result;
}
dbus_bool_t
_dbus_read_nonce (const DBusString *fname, DBusString *nonce, DBusError* error)
{
FILE *fp;
char buffer[17];
size_t nread;
buffer[sizeof buffer - 1] = '\0';
_DBUS_ASSERT_ERROR_IS_CLEAR (error);
_dbus_verbose ("reading nonce from file: %s\n", _dbus_string_get_const_data (fname));
fp = fopen (_dbus_string_get_const_data (fname), "rb");
if (!fp)
return FALSE;
nread = fread (buffer, 1, sizeof buffer - 1, fp);
fclose (fp);
if (!nread)
{
dbus_set_error (error, DBUS_ERROR_FILE_NOT_FOUND, "Could not read nonce from file %s", _dbus_string_get_const_data (fname));
return FALSE;
}
if (!_dbus_string_append_len (nonce, buffer, sizeof buffer - 1 ))
{
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
return FALSE;
}
return TRUE;
}
int
_dbus_accept_with_noncefile (int listen_fd, const DBusNonceFile *noncefile)
{
int fd;
DBusString nonce;
_dbus_assert (noncefile != NULL);
if (!_dbus_string_init (&nonce))
return -1;
//PENDING(kdab): set better errors
if (_dbus_read_nonce (_dbus_noncefile_get_path(noncefile), &nonce, NULL) != TRUE)
return -1;
fd = _dbus_accept (listen_fd);
if (_dbus_socket_is_invalid (fd))
return fd;
if (do_check_nonce(fd, &nonce, NULL) != TRUE) {
_dbus_verbose ("nonce check failed. Closing socket.\n");
_dbus_close_socket(fd, NULL);
return -1;
}
return fd;
}
static dbus_bool_t
generate_and_write_nonce (const DBusString *filename, DBusError *error)
{
DBusString nonce;
dbus_bool_t ret;
_DBUS_ASSERT_ERROR_IS_CLEAR (error);
if (!_dbus_string_init (&nonce))
{
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
return FALSE;
}
if (!_dbus_generate_random_bytes (&nonce, 16))
{
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
_dbus_string_free (&nonce);
return FALSE;
}
ret = _dbus_string_save_to_file (&nonce, filename, FALSE, error);
_dbus_string_free (&nonce);
return ret;
}
dbus_bool_t
_dbus_send_nonce (int fd, const DBusString *noncefile, DBusError *error)
{
dbus_bool_t read_result;
int send_result;
DBusString nonce;
_DBUS_ASSERT_ERROR_IS_CLEAR (error);
if (_dbus_string_get_length (noncefile) == 0)
return FALSE;
if (!_dbus_string_init (&nonce))
{
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
return FALSE;
}
read_result = _dbus_read_nonce (noncefile, &nonce, error);
if (!read_result)
{
_DBUS_ASSERT_ERROR_IS_SET (error);
_dbus_string_free (&nonce);
return FALSE;
}
_DBUS_ASSERT_ERROR_IS_CLEAR (error);
send_result = _dbus_write_socket (fd, &nonce, 0, _dbus_string_get_length (&nonce));
_dbus_string_free (&nonce);
if (send_result == -1)
{
dbus_set_error (error,
_dbus_error_from_system_errno (),
"Failed to send nonce (fd=%d): %s",
fd, _dbus_strerror_from_errno ());
return FALSE;
}
return TRUE;
}
static dbus_bool_t
do_noncefile_create (DBusNonceFile *noncefile,
DBusError *error,
dbus_bool_t use_subdir)
{
DBusString randomStr;
_DBUS_ASSERT_ERROR_IS_CLEAR (error);
_dbus_assert (noncefile);
if (!_dbus_string_init (&randomStr))
{
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
goto on_error;
}
if (!_dbus_generate_random_ascii (&randomStr, 8))
{
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
goto on_error;
}
if (!_dbus_string_init (&noncefile->dir)
|| !_dbus_string_append (&noncefile->dir, _dbus_get_tmpdir()))
{
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
goto on_error;
}
if (use_subdir)
{
if (!_dbus_string_append (&noncefile->dir, "/dbus_nonce-")
|| !_dbus_string_append (&noncefile->dir, _dbus_string_get_const_data (&randomStr)) )
{
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
goto on_error;
}
if (!_dbus_string_init (&noncefile->path)
|| !_dbus_string_copy (&noncefile->dir, 0, &noncefile->path, 0)
|| !_dbus_string_append (&noncefile->path, "/nonce"))
{
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
goto on_error;
}
if (!_dbus_create_directory (&noncefile->dir, error))
{
_DBUS_ASSERT_ERROR_IS_SET (error);
goto on_error;
}
_DBUS_ASSERT_ERROR_IS_CLEAR (error);
}
else
{
if (!_dbus_string_init (&noncefile->path)
|| !_dbus_string_copy (&noncefile->dir, 0, &noncefile->path, 0)
|| !_dbus_string_append (&noncefile->path, "/dbus_nonce-")
|| !_dbus_string_append (&noncefile->path, _dbus_string_get_const_data (&randomStr)))
{
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
goto on_error;
}
}
if (!generate_and_write_nonce (&noncefile->path, error))
{
_DBUS_ASSERT_ERROR_IS_SET (error);
if (use_subdir)
_dbus_delete_directory (&noncefile->dir, NULL); //we ignore possible errors deleting the dir and return the write error instead
goto on_error;
}
_DBUS_ASSERT_ERROR_IS_CLEAR (error);
_dbus_string_free (&randomStr);
return TRUE;
on_error:
if (use_subdir)
_dbus_delete_directory (&noncefile->dir, NULL);
_dbus_string_free (&noncefile->dir);
_dbus_string_free (&noncefile->path);
_dbus_string_free (&randomStr);
return FALSE;
}
#ifdef DBUS_WIN
dbus_bool_t
_dbus_noncefile_create (DBusNonceFile *noncefile,
DBusError *error)
{
return do_noncefile_create (noncefile, error, /*use_subdir=*/ FALSE);
}
dbus_bool_t
_dbus_noncefile_delete (DBusNonceFile *noncefile,
DBusError *error)
{
_DBUS_ASSERT_ERROR_IS_CLEAR (error);
_dbus_delete_file (&noncefile->path, error);
_dbus_string_free (&noncefile->dir);
_dbus_string_free (&noncefile->path);
return TRUE;
}
#else
dbus_bool_t
_dbus_noncefile_create (DBusNonceFile *noncefile,
DBusError *error)
{
return do_noncefile_create (noncefile, error, /*use_subdir=*/ TRUE);
}
dbus_bool_t
_dbus_noncefile_delete (DBusNonceFile *noncefile,
DBusError *error)
{
_DBUS_ASSERT_ERROR_IS_CLEAR (error);
_dbus_delete_directory (&noncefile->dir, error);
_dbus_string_free (&noncefile->dir);
_dbus_string_free (&noncefile->path);
return TRUE;
}
#endif
const DBusString*
_dbus_noncefile_get_path (const DBusNonceFile *noncefile)
{
_dbus_assert (noncefile);
return &noncefile->path;
}
dbus_bool_t
_dbus_noncefile_check_nonce (int fd,
const DBusNonceFile *noncefile,
DBusError* error)
{
return do_check_nonce (fd, _dbus_noncefile_get_path (noncefile), error);
}