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
|
/* just a "stupid" secure SUID wrapper for the parabolaweb-changepassword script */
/* Copyright (C) 2014 Luke Shumaker <lukeshu@parabola.nu>
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*/
#define _GNU_SOURCE /* for environment functions and asprintf(3) */
#include <errno.h> /* for errno */
#include <error.h> /* for error(3) */
#include <pwd.h> /* for getpwuid(3) */
#include <stdlib.h> /* for free(3) and environment functions */
#include <unistd.h> /* for getuid(3), geteuid(3), setreuid(3), execl(3) */
#include <stdio.h> /* for asprintf(3) in atoi() */
void
mysetenv(const char *name, const char *value)
{
if (value != NULL) {
if (setenv(name, value, 1) != 0) {
error(127, errno, "could not set %s", name);
}
}
}
void
xfree(void *ptr) {
if (ptr != NULL)
free(ptr);
}
char *
itoa(long i) {
char *a = NULL;
int r = asprintf(&a, "%ld", i);
if (r < 0) {
xfree(a);
return NULL;
}
return a;
}
void
sanitize_environment()
{
char *a = NULL;
struct passwd *user = NULL;
const char *env_term = getenv("TERM" );
const char *env_lang = getenv("LANG" );
const char *env_lc_all = getenv("LC_ALL" );
const char *env_lc_collate = getenv("LC_COLLATE" );
const char *env_lc_ctype = getenv("LC_CTYPE" );
const char *env_lc_messages = getenv("LC_MESSAGES" );
const char *env_lc_monetary = getenv("LC_MONETARY" );
const char *env_lc_numeric = getenv("LC_NUMERIC" );
const char *env_lc_time = getenv("LC_TIME" );
/* NOTE: In the main program, make sure that SUID_USER is priveleged
before trusting SUDO_* */
const char *env_sudo_user = getenv("SUDO_USER" );
const char *env_sudo_uid = getenv("SUDO_UID" );
const char *env_sudo_gid = getenv("SUDO_GID" );
const char *env_sudo_command = getenv("SUDO_COMMAND");
clearenv();
mysetenv("TERM" , env_term );
mysetenv("LANG" , env_lang );
mysetenv("LC_ALL" , env_lc_all );
mysetenv("LC_COLLATE" , env_lc_collate );
mysetenv("LC_CTYPE" , env_lc_ctype );
mysetenv("LC_MESSAGES" , env_lc_messages );
mysetenv("LC_MONETARY" , env_lc_monetary );
mysetenv("LC_NUMERIC" , env_lc_numeric );
mysetenv("LC_TIME" , env_lc_time );
mysetenv("SUDO_USER" , env_sudo_user );
mysetenv("SUDO_UID" , env_sudo_uid );
mysetenv("SUDO_GID" , env_sudo_gid );
mysetenv("SUDO_COMMAND", env_sudo_command);
user = getpwuid(getuid());
/* similar to SUDO_* */
mysetenv("SUID_USER", user->pw_name );
mysetenv("SUID_UID" , a=itoa(user->pw_uid)); xfree(a);
mysetenv("SUID_GID" , a=itoa(user->pw_gid)); xfree(a);
if (setreuid(geteuid(), -1) != 0)
error(127, errno, "setreuid");
user = getpwuid(geteuid());
mysetenv("USER" , user->pw_name);
mysetenv("LOGNAME", user->pw_name);
mysetenv("HOME" , user->pw_dir );
}
int
main(int argc, char **argv)
{
if (getuid() != 0)
sanitize_environment();
execv(SCRIPT_LOCATION, argv);
error(127, errno, "could not exec actual program: %s", SCRIPT_LOCATION);
}
|
