source: trunk/src/sh_prelink.c@ 375

Last change on this file since 375 was 374, checked in by katerina, 13 years ago

Patch for ticket #255 (intruder on server). Also disable setting prelink/ps path with --disable-shellexpand.
File size: 7.9 KB
Line 
1/* SAMHAIN file system integrity testing */
2/* Copyright (C) 2004 Rainer Wichmann */
3/* */
4/* This program is free software; you can redistribute it */
5/* and/or modify */
6/* it under the terms of the GNU General Public License as */
7/* published by */
8/* the Free Software Foundation; either version 2 of the License, or */
9/* (at your option) any later version. */
10/* */
11/* This program is distributed in the hope that it will be useful, */
12/* but WITHOUT ANY WARRANTY; without even the implied warranty of */
13/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */
14/* GNU General Public License for more details. */
15/* */
16/* You should have received a copy of the GNU General Public License */
17/* along with this program; if not, write to the Free Software */
18/* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
19
20#include "config_xor.h"
21
22#include <string.h>
23#include <sys/types.h>
24#include <signal.h>
25
26#if defined(SH_WITH_CLIENT) || defined(SH_STANDALONE)
27
28#include "samhain.h"
29#include "sh_tiger.h"
30#include "sh_extern.h"
31#include "sh_utils.h"
32#include "sh_unix.h"
33
34#undef FIL__
35#define FIL__ _("sh_prelink.c")
36
37static char * prelink_path = NULL;
38static char * prelink_hash = NULL;
39
40int sh_prelink_set_path (const char * str)
41{
42 SL_ENTER(_("sh_prelink_set_path"));
43 if (prelink_path != NULL)
44 SH_FREE(prelink_path);
45 if (str[0] != '/')
46 {
47 prelink_path = NULL;
48 SL_RETURN((-1), _("sh_prelink_set_path"));
49 }
50#ifdef SH_EVAL_SHELL
51 prelink_path = sh_util_strdup(str);
52 SL_RETURN(0, _("sh_prelink_set_path"));
53#else
54 prelink_path = NULL;
55 SL_RETURN((-1), _("sh_prelink_set_path"));
56#endif
57}
58
59int sh_prelink_set_hash (const char * str)
60{
61 size_t len;
62 SL_ENTER(_("sh_prelink_set_hash"));
63 if (prelink_hash != NULL)
64 SH_FREE(prelink_hash);
65 len = sl_strlen (str);
66 if (len != KEY_LEN)
67 {
68 prelink_hash = NULL;
69 SL_RETURN((-1), _("sh_prelink_set_hash"));
70 }
71 prelink_hash = SH_ALLOC(len+1);
72 (void) sl_strlcpy(prelink_hash, str, len+1);
73 SL_RETURN(0, _("sh_prelink_set_hash"));
74}
75
76int sh_prelink_iself (SL_TICKET fd, off_t size, int alert_timeout, char * path)
77{
78 long status;
79 char magic[4];
80 char * tmp;
81
82 /* 42 bytes is about the minimum an ELF binary might have
83 * (with plenty of hacks to reduce the size, such as interleaving
84 * the code with the header...)
85 */
86 if (size < 42)
87 return S_FALSE;
88
89 status = sl_read_timeout (fd, magic, 4, alert_timeout, SL_FALSE);
90 (void) sl_rewind(fd);
91 if (status == 4)
92 {
93 /*@-usedef@*/
94 if (magic[0] == (char) 0x7f &&
95 magic[1] == 'E' &&
96 magic[2] == 'L' &&
97 magic[3] == 'F')
98 return S_TRUE;
99 /*@+usedef@*/
100 }
101 else
102 {
103 tmp = sh_util_safe_name (path);
104 sh_error_handle(SH_ERR_ERR, FIL__, __LINE__, status, MSG_E_SUBGPATH,
105 _("Error reading file"), _("sh_prelink_iself"), tmp);
106 SH_FREE(path);
107 }
108 return S_FALSE;
109}
110
111extern int get_the_fd (SL_TICKET ticket);
112
113static void sh_prelink_fd(sh_tas_t * task)
114{
115 SL_TICKET ticket;
116 char * tmp;
117 char hashbuf[KEYBUF_SIZE];
118
119 if (task->com_ti != (-1))
120 {
121 (void) sl_close(task->com_ti);
122 task->com_fd = -1;
123 task->com_ti = -1;
124 }
125 ticket = sl_open_read(FIL__, __LINE__, task->command,
126 task->privileged == 0 ? SL_NOPRIV : SL_YESPRIV);
127 if (SL_ISERROR(ticket))
128 {
129 char errbuf[SH_ERRBUF_SIZE];
130 char errbuf2[SH_ERRBUF_SIZE];
131 sh_error_message(errno, errbuf2, sizeof(errbuf2));
132 sl_strlcpy(errbuf, sl_error_string(ticket), sizeof(errbuf));
133 tmp = sh_util_safe_name (task->command);
134 sh_error_handle(SH_ERR_ERR, FIL__, __LINE__, ticket, MSG_E_READ, errbuf, errbuf2, tmp);
135 SH_FREE(tmp);
136 return;
137 }
138
139 if (*(task->checksum) == '\0' ||
140 0 == sl_strcmp(task->checksum,
141 sh_tiger_hash (task->command, ticket, TIGER_NOLIM, hashbuf, sizeof(hashbuf))))
142 {
143 task->com_fd = get_the_fd(ticket);
144 task->com_ti = ticket;
145 }
146 else
147 {
148 tmp = sh_util_safe_name (task->command);
149 sh_error_handle(SH_ERR_ERR, FIL__, __LINE__, ticket, MSG_E_HASH, tmp);
150 SH_FREE(tmp);
151 (void) sl_close(ticket);
152 }
153 return;
154}
155
156/* returns static storage
157 */
158int sh_prelink_run (char * path, char * file_hash, int alert_timeout)
159{
160 static int init = S_FALSE;
161 static int args_filled = 0;
162 static sh_tas_t task;
163
164 int status = 0;
165 char * p;
166 struct sigaction new_act;
167 struct sigaction old_act;
168
169 SL_ENTER(_("sh_prelink_run"));
170
171 /* reset if path == NULL
172 */
173 if (path == NULL)
174 {
175 if (init == S_FALSE)
176 {
177 SL_RETURN (0, _("sh_prelink_run"));
178 }
179 sh_ext_tas_free(&task);
180 init = S_FALSE;
181 args_filled = 0;
182 SL_RETURN (0, _("sh_prelink_run"));
183 }
184
185 /* initialize task structure
186 */
187 if (init == S_FALSE)
188 {
189 char dir[SH_PATHBUF];
190
191 sh_ext_tas_init(&task);
192 p = sh_unix_getUIDdir (SH_ERR_ERR, task.run_user_uid, dir, sizeof(dir));
193 if (p)
194 {
195 (void) sh_ext_tas_add_envv (&task, _("HOME"), p);
196 }
197 (void) sh_ext_tas_add_envv (&task, _("SHELL"),
198 _("/bin/sh"));
199 (void) sh_ext_tas_add_envv (&task, _("PATH"),
200 _("/sbin:/usr/sbin:/bin:/usr/bin"));
201 if (sh.timezone != NULL)
202 {
203 (void) sh_ext_tas_add_envv(&task, "TZ", sh.timezone);
204 }
205 if (prelink_path == NULL)
206 {
207 sh_ext_tas_command(&task, _("/usr/sbin/prelink"));
208 (void) sh_ext_tas_add_argv(&task, _("/usr/sbin/prelink"));
209 }
210 else
211 {
212 sh_ext_tas_command(&task, prelink_path);
213 (void) sh_ext_tas_add_argv(&task, prelink_path);
214 }
215 args_filled = sh_ext_tas_add_argv(&task, _("--verify"));
216
217 if (prelink_hash != NULL)
218 {
219 (void) sl_strlcpy(task.checksum, prelink_hash, KEY_LEN+1);
220 }
221 task.rw = 'r';
222 task.fork_twice = S_FALSE;
223
224 sh_prelink_fd(&task);
225
226 init = S_TRUE;
227 }
228
229 /* rm filename arg if set; fill in filename
230 */
231 if (args_filled == 3)
232 args_filled = sh_ext_tas_rm_argv(&task);
233 if (args_filled == 2)
234 args_filled = sh_ext_tas_add_argv(&task, path);
235 else
236 {
237 sh_error_handle(SH_ERR_ERR, FIL__, __LINE__, args_filled, MSG_E_SUBGEN,
238 _("Bad argument count"), _("sh_prelink_run"));
239 SL_RETURN ((-1), _("sh_prelink_run"));
240 }
241
242 /* open pipe
243 */
244 status = sh_ext_popen(&task);
245 if (status != 0)
246 {
247 sh_error_handle(SH_ERR_ALL, FIL__, __LINE__, status, MSG_E_SUBGEN,
248 _("Could not open pipe"), _("sh_prelink_run"));
249 SL_RETURN ((-1), _("sh_prelink_run"));
250 }
251
252 if (SL_ISERROR(task.pipeTI))
253 {
254 sh_error_handle(SH_ERR_ALL, FIL__, __LINE__, task.pipeTI, MSG_E_SUBGEN,
255 _("No valid ticket"), _("sh_prelink_run"));
256 SL_RETURN ((-1), _("sh_prelink_run"));
257 }
258
259 /* ignore SIGPIPE (instead get EPIPE if connection is closed)
260 */
261 new_act.sa_handler = SIG_IGN;
262 (void) retry_sigaction (FIL__, __LINE__, SIGPIPE, &new_act, &old_act);
263
264 /* read from pipe
265 */
266 sl_read_timeout_prep (task.pipeTI);
267
268 {
269 char hashbuf[KEYBUF_SIZE];
270 UINT64 length_nolim = TIGER_NOLIM;
271 sl_strlcpy(file_hash,
272 sh_tiger_generic_hash (path, task.pipeTI, &length_nolim, alert_timeout,
273 hashbuf, sizeof(hashbuf)),
274 KEY_LEN+1);
275 }
276
277 /* restore old signal handler
278 */
279 (void) retry_sigaction (FIL__, __LINE__, SIGPIPE, &old_act, NULL);
280
281 /* close pipe and return exit status
282 */
283 status = sh_ext_pclose(&task);
284 SL_RETURN ((status), _("sh_prelink_run"));
285}
286/* defined(SH_WITH_CLIENT) || defined(SH_STANDALONE)
287 */
288#endif
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