path: root/loginutils/sulogin.c (plain)
blob: c8e5fc9a00544f897cadea30d3b13578ac464e77

1	/* vi: set sw=4 ts=4: */
2	/*
3	* Mini sulogin implementation for busybox
4	*
5	* Licensed under GPLv2 or later, see file LICENSE in this source tree.
6	*/
7
8	//usage:#define sulogin_trivial_usage
9	//usage: "[-t N] [TTY]"
10	//usage:#define sulogin_full_usage "\n\n"
11	//usage: "Single user login\n"
12	//usage: "\n -t N Timeout"
13
14	#include "libbb.h"
15	#include <syslog.h>
16
17	int sulogin_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
18	int sulogin_main(int argc UNUSED_PARAM, char **argv)
19	{
20	int timeout = 0;
21	struct passwd *pwd;
22	const char *shell;
23
24	logmode = LOGMODE_BOTH;
25	openlog(applet_name, 0, LOG_AUTH);
26
27	opt_complementary = "t+"; /* -t N */
28	getopt32(argv, "t:", &timeout);
29	argv += optind;
30
31	if (argv[0]) {
32	close(0);
33	close(1);
34	dup(xopen(argv[0], O_RDWR));
35	close(2);
36	dup(0);
37	}
38
39	/* Malicious use like "sulogin /dev/sda"? */
40	if (!isatty(0) || !isatty(1) || !isatty(2)) {
41	logmode = LOGMODE_SYSLOG;
42	bb_error_msg_and_die("not a tty");
43	}
44
45	/* Clear dangerous stuff, set PATH */
46	sanitize_env_if_suid();
47
48	pwd = safegetpwuid(0);
49	if (!pwd) {
50	goto auth_error;
51	}
52
53	while (1) {
54	int r;
55
56	r = ask_and_check_password_extended(pwd, timeout,
57	"Give root password for system maintenance\n"
58	"(or type Control-D for normal startup):"
59	);
60	if (r < 0) {
61	/* ^D, ^C, timeout, or read error */
62	bb_info_msg("Normal startup");
63	return 0;
64	}
65	if (r > 0) {
66	break;
67	}
68	bb_do_delay(LOGIN_FAIL_DELAY);
69	bb_info_msg("Login incorrect");
70	}
71
72	bb_info_msg("System Maintenance Mode");
73
74	IF_SELINUX(renew_current_security_context());
75
76	shell = getenv("SUSHELL");
77	if (!shell)
78	shell = getenv("sushell");
79	if (!shell)
80	shell = pwd->pw_shell;
81
82	/* Exec login shell with no additional parameters. Never returns. */
83	run_shell(shell, 1, NULL, NULL);
84
85	auth_error:
86	bb_error_msg_and_die("no password entry for root");
87	}
88