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
|
/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*-
*
* GDM - The GNOME Display Manager
* Copyright (C) 1998, 1999, 2000 Martin K. Petersen <mkp@mkp.net>
*
* 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"
#include <glib/gi18n.h>
#include <sys/stat.h>
#include "gdm.h"
#include "gdm-common.h"
#include "gdm-daemon-config.h"
#include "filecheck.h"
/**
* gdm_file_check:
* @caller: String to be prepended to error messages.
* @user: User id for the user owning the file/dir.
* @dir: Directory to be examined.
* @file: File to be examined.
* @absentok: Accept absent files if TRUE.
* @absentdirok: Absent directory returns FALSE but without complaining
* @maxsize: Maximum acceptable filesize in KB. 0 to disable.
* @perms: 0 to allow user writable file/dir only. 1 to allow group and 2 to allow global writable file/dir.
*
* Examines a file to determine whether it is safe for the daemon to write to it.
*/
/* we should be euid the user BTW */
gboolean
gdm_file_check (const gchar *caller,
uid_t user,
const gchar *dir,
const gchar *file,
gboolean absentok,
gboolean absentdirok,
gint maxsize,
gint perms)
{
struct stat statbuf;
gchar *fullpath;
gchar *dirautofs;
int r;
if (ve_string_empty (dir) ||
ve_string_empty (file))
return FALSE;
/* Stat on automounted directory - append the '/.' to dereference mount point.
Do this only if GdmSupportAutomount is true (default is false)
2006-09-22, Jerzy Borkowski, CAMK */
if G_UNLIKELY (gdm_daemon_config_get_value_bool (GDM_KEY_SUPPORT_AUTOMOUNT)) {
dirautofs = g_strconcat(dir, "/.", NULL);
VE_IGNORE_EINTR (r = stat (dirautofs, &statbuf));
g_free(dirautofs);
}
/* Stat directory */
else {
VE_IGNORE_EINTR (r = stat (dir, &statbuf));
}
if (r < 0) {
if ( ! absentdirok)
g_warning (_("%s: Directory %s does not exist."),
caller, dir);
return FALSE;
}
/* Check if dir is owned by the user ...
Only, if GDM_KEY_CHECK_DIR_OWNER is true (default)
This is a "hack" for directories not owned by
the user.
2004-06-22, Andreas Schubert, MATHEMA Software GmbH */
if G_UNLIKELY (gdm_daemon_config_get_value_bool (GDM_KEY_CHECK_DIR_OWNER) && (statbuf.st_uid != user)) {
g_warning (_("%s: %s is not owned by uid %d."), caller, dir, user);
return FALSE;
}
/* ... if group has write permission ... */
if G_UNLIKELY (perms < 1 && (statbuf.st_mode & S_IWGRP) == S_IWGRP) {
g_warning (_("%s: %s is writable by group."), caller, dir);
return FALSE;
}
/* ... and if others have write permission. */
if G_UNLIKELY (perms < 2 && (statbuf.st_mode & S_IWOTH) == S_IWOTH) {
g_warning (_("%s: %s is writable by other."), caller, dir);
return FALSE;
}
fullpath = g_build_filename (dir, file, NULL);
/* Stat file */
VE_IGNORE_EINTR (r = g_stat (fullpath, &statbuf));
if (r < 0) {
/* Return true if file does not exist and that is ok */
if (absentok) {
g_free (fullpath);
return TRUE;
}
else {
g_warning (_("%s: %s does not exist but must exist."), caller, fullpath);
g_free (fullpath);
return FALSE;
}
}
/* Check that it is a regular file ... */
if G_UNLIKELY (! S_ISREG (statbuf.st_mode)) {
g_warning (_("%s: %s is not a regular file."), caller, fullpath);
g_free (fullpath);
return FALSE;
}
/* ... owned by the user ... */
if G_UNLIKELY (statbuf.st_uid != user) {
g_warning (_("%s: %s is not owned by uid %d."), caller, fullpath, user);
g_free (fullpath);
return FALSE;
}
/* ... unwritable by group ... */
if G_UNLIKELY (perms < 1 && (statbuf.st_mode & S_IWGRP) == S_IWGRP) {
g_warning (_("%s: %s is writable by group."), caller, fullpath);
g_free (fullpath);
return FALSE;
}
/* ... unwritable by others ... */
if G_UNLIKELY (perms < 2 && (statbuf.st_mode & S_IWOTH) == S_IWOTH) {
g_warning (_("%s: %s is writable by group/other."), caller, fullpath);
g_free (fullpath);
return FALSE;
}
/* ... and smaller than sysadmin specified limit. */
if G_UNLIKELY (maxsize && statbuf.st_size > maxsize) {
g_warning (_("%s: %s is bigger than sysadmin specified maximum file size."),
caller, fullpath);
g_free (fullpath);
return FALSE;
}
g_free (fullpath);
/* Yeap, this file is ok */
return TRUE;
}
/* we should be euid the user BTW */
gboolean
gdm_auth_file_check (const gchar *caller,
uid_t user,
const gchar *authfile,
gboolean absentok,
struct stat *s)
{
struct stat statbuf;
gint usermaxfile;
int r;
if (ve_string_empty (authfile))
return FALSE;
/* Stat file */
VE_IGNORE_EINTR (r = g_lstat (authfile, &statbuf));
if (s != NULL)
*s = statbuf;
if (r < 0) {
if (absentok)
return TRUE;
g_warning (_("%s: %s does not exist but must exist."), caller, authfile);
return FALSE;
}
/* Check that it is a regular file ... */
if G_UNLIKELY (! S_ISREG (statbuf.st_mode)) {
g_warning (_("%s: %s is not a regular file."), caller, authfile);
return FALSE;
}
/* ... owned by the user ... */
if G_UNLIKELY (statbuf.st_uid != user) {
g_warning (_("%s: %s is not owned by uid %d."), caller, authfile, user);
return FALSE;
}
/* ... has right permissions ... */
if G_UNLIKELY (statbuf.st_mode & 0077) {
g_warning ("%s: %s has wrong permissions (should be 0600)", caller, authfile);
return FALSE;
}
usermaxfile = gdm_daemon_config_get_value_int (GDM_KEY_USER_MAX_FILE);
/* ... and smaller than sysadmin specified limit. */
if G_UNLIKELY (usermaxfile && statbuf.st_size > usermaxfile) {
g_warning (_("%s: %s is bigger than sysadmin specified maximum file size."),
caller, authfile);
return FALSE;
}
/* Yeap, this file is ok */
return TRUE;
}
|
