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
|
/* vi: set sw=4 ts=4: */
/*
* Mini su implementation for busybox
*
* Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
*/
#include "libbb.h"
#include <syslog.h>
#if ENABLE_FEATURE_SU_CHECKS_SHELLS
/* Return 1 if SHELL is a restricted shell (one not returned by
* getusershell), else 0, meaning it is a standard shell. */
static int restricted_shell(const char *shell)
{
char *line;
int result = 1;
/*setusershell(); - getusershell does it itself*/
while ((line = getusershell()) != NULL) {
if (/* *line != '#' && */ strcmp(line, shell) == 0) {
result = 0;
break;
}
}
if (ENABLE_FEATURE_CLEAN_UP)
endusershell();
return result;
}
#endif
#define SU_OPT_mp (3)
#define SU_OPT_l (4)
int su_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int su_main(int argc UNUSED_PARAM, char **argv)
{
unsigned flags;
char *opt_shell = NULL;
char *opt_command = NULL;
const char *opt_username = "root";
struct passwd *pw;
uid_t cur_uid = getuid();
const char *tty;
char user_buf[64];
const char *old_user;
flags = getopt32(argv, "mplc:s:", &opt_command, &opt_shell);
//argc -= optind;
argv += optind;
if (argv[0] && LONE_DASH(argv[0])) {
flags |= SU_OPT_l;
argv++;
}
/* get user if specified */
if (argv[0]) {
opt_username = argv[0];
argv++;
}
if (ENABLE_FEATURE_SU_SYSLOG) {
/* The utmp entry (via getlogin) is probably the best way to
* identify the user, especially if someone su's from a su-shell.
* But getlogin can fail -- usually due to lack of utmp entry.
* in this case resort to getpwuid. */
#if ENABLE_FEATURE_UTMP
old_user = user_buf;
if (getlogin_r(user_buf, sizeof(user_buf)) != 0)
#endif
{
pw = getpwuid(cur_uid);
old_user = pw ? xstrdup(pw->pw_name) : "";
}
tty = xmalloc_ttyname(2);
if (!tty) {
tty = "none";
}
openlog(applet_name, 0, LOG_AUTH);
}
pw = xgetpwnam(opt_username);
if (cur_uid == 0 || correct_password(pw)) {
if (ENABLE_FEATURE_SU_SYSLOG)
syslog(LOG_NOTICE, "%c %s %s:%s",
'+', tty, old_user, opt_username);
} else {
if (ENABLE_FEATURE_SU_SYSLOG)
syslog(LOG_NOTICE, "%c %s %s:%s",
'-', tty, old_user, opt_username);
bb_error_msg_and_die("incorrect password");
}
if (ENABLE_FEATURE_CLEAN_UP && ENABLE_FEATURE_SU_SYSLOG) {
closelog();
}
if (!opt_shell && (flags & SU_OPT_mp)) {
/* -s SHELL is not given, but "preserve env" opt is */
opt_shell = getenv("SHELL");
}
/* Make sure pw->pw_shell is non-NULL. It may be NULL when NEW_USER
* is a username that is retrieved via NIS (YP), that doesn't have
* a default shell listed. */
if (!pw->pw_shell || !pw->pw_shell[0])
pw->pw_shell = (char *)DEFAULT_SHELL;
#if ENABLE_FEATURE_SU_CHECKS_SHELLS
if (opt_shell && cur_uid != 0 && restricted_shell(pw->pw_shell)) {
/* The user being su'd to has a nonstandard shell, and so is
* probably a uucp account or has restricted access. Don't
* compromise the account by allowing access with a standard
* shell. */
bb_error_msg("using restricted shell");
opt_shell = NULL;
}
/* else: user can run whatever he wants via "su -s PROG USER".
* This is safe since PROG is run under user's uid/gid. */
#endif
if (!opt_shell)
opt_shell = pw->pw_shell;
change_identity(pw);
setup_environment(opt_shell,
((flags & SU_OPT_l) / SU_OPT_l * SETUP_ENV_CLEARENV)
+ (!(flags & SU_OPT_mp) * SETUP_ENV_CHANGEENV),
pw);
IF_SELINUX(set_current_security_context(NULL);)
/* Never returns */
run_shell(opt_shell, flags & SU_OPT_l, opt_command, (const char**)argv);
/* return EXIT_FAILURE; - not reached */
}
|
