busybox/loginutils/login.c

/* vi: set sw=4 ts=4: */
/*
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include "busybox.h"
#include <utmp.h>
#include <sys/resource.h>
#include <syslog.h>

#ifdef CONFIG_SELINUX
#include <selinux/selinux.h>  /* for is_selinux_enabled()  */
#include <selinux/get_context_list.h> /* for get_default_context() */
#include <selinux/flask.h> /* for security class definitions  */
#include <errno.h>
#endif

enum {
	TIMEOUT = 60,
	EMPTY_USERNAME_COUNT = 10,
	USERNAME_SIZE = 32,
	TTYNAME_SIZE = 32,
};

static char full_tty[TTYNAME_SIZE];
static char* short_tty = full_tty;

#if ENABLE_FEATURE_UTMP
/* vv  Taken from tinylogin utmp.c  vv */
/*
 * read_or_build_utent - see if utmp file is correct for this process
 *
 *	System V is very picky about the contents of the utmp file
 *	and requires that a slot for the current process exist.
 *	The utmp file is scanned for an entry with the same process
 *	ID.  If no entry exists the process exits with a message.
 *
 *	The "picky" flag is for network and other logins that may
 *	use special flags.  It allows the pid checks to be overridden.
 *	This means that getty should never invoke login with any
 *	command line flags.
 */

static struct utmp utent;

static void read_or_build_utent(int picky)
{
	struct utmp *ut;
	pid_t pid = getpid();

	setutent();

	/* First, try to find a valid utmp entry for this process.  */
	while ((ut = getutent()))
		if (ut->ut_pid == pid && ut->ut_line[0] && ut->ut_id[0] &&
		(ut->ut_type == LOGIN_PROCESS || ut->ut_type == USER_PROCESS))
			break;

	/* If there is one, just use it, otherwise create a new one.  */
	if (ut) {
		utent = *ut;
	} else {
		if (picky)
			bb_error_msg_and_die("no utmp entry found");

		memset(&utent, 0, sizeof(utent));
		utent.ut_type = LOGIN_PROCESS;
		utent.ut_pid = pid;
		strncpy(utent.ut_line, short_tty, sizeof(utent.ut_line));
		/* This one is only 4 chars wide. Try to fit something
		 * remotely meaningful by skipping "tty"... */
		strncpy(utent.ut_id, short_tty + 3, sizeof(utent.ut_id));
		strncpy(utent.ut_user, "LOGIN", sizeof(utent.ut_user));
		utent.ut_time = time(NULL);
	}
	if (!picky)	/* root login */
		memset(utent.ut_host, 0, sizeof(utent.ut_host));
}

/*
 * write_utent - put a USER_PROCESS entry in the utmp file
 *
 *	write_utent changes the type of the current utmp entry to
 *	USER_PROCESS.  the wtmp file will be updated as well.
 */
static void write_utent(const char *username)
{
	utent.ut_type = USER_PROCESS;
	strncpy(utent.ut_user, username, sizeof(utent.ut_user));
	utent.ut_time = time(NULL);
	/* other fields already filled in by read_or_build_utent above */
	setutent();
	pututline(&utent);
	endutent();
#if ENABLE_FEATURE_WTMP
	if (access(bb_path_wtmp_file, R_OK|W_OK) == -1) {
		close(creat(bb_path_wtmp_file, 0664));
	}
	updwtmp(bb_path_wtmp_file, &utent);
#endif
}
#else /* !ENABLE_FEATURE_UTMP */
static inline void read_or_build_utent(int ATTRIBUTE_UNUSED picky) {}
static inline void write_utent(const char ATTRIBUTE_UNUSED *username) {}
#endif /* !ENABLE_FEATURE_UTMP */

static void die_if_nologin_and_non_root(int amroot)
{
	FILE *fp;
	int c;

	if (access(bb_path_nologin_file, F_OK))
		return;

	fp = fopen(bb_path_nologin_file, "r");
	if (fp) {
		while ((c = getc(fp)) != EOF)
			putchar((c=='\n') ? '\r' : c);
		fflush(stdout);
		fclose(fp);
	} else
		puts("\r\nSystem closed for routine maintenance\r");
	if (!amroot)
		exit(1);
	puts("\r\n[Disconnect bypassed -- root login allowed.]\r");
}

#if ENABLE_FEATURE_SECURETTY
static int check_securetty(void)
{
	FILE *fp;
	int i;
	char buf[BUFSIZ];

	fp = fopen(bb_path_securetty_file, "r");
	if (!fp) {
		/* A missing securetty file is not an error. */
		return 1;
	}
	while (fgets(buf, sizeof(buf)-1, fp)) {
		for (i = strlen(buf)-1; i>=0; --i) {
			if (!isspace(buf[i]))
				break;
		}
		buf[++i] = '\0';
		if ((buf[0]=='\0') || (buf[0]=='#'))
			continue;
		if (strcmp(buf, short_tty) == 0) {
			fclose(fp);
			return 1;
		}
	}
	fclose(fp);
	return 0;
}
#else
static inline int check_securetty(void) { return 1; }
#endif

static void get_username_or_die(char *buf, int size_buf)
{
	int c, cntdown;
	cntdown = EMPTY_USERNAME_COUNT;
prompt:
	/* skip whitespace */
	print_login_prompt();
	do {
		c = getchar();
		if (c == EOF) exit(1);
		if (c == '\n') {
			if (!--cntdown) exit(1);
			goto prompt;
		}
	} while (isspace(c));

	*buf++ = c;
	if (!fgets(buf, size_buf-2, stdin))
		exit(1);
	if (!strchr(buf, '\n'))
		exit(1);
	while (isgraph(*buf)) buf++;
	*buf = '\0';
}

static void motd(void)
{
	FILE *fp;
	int c;

	fp = fopen(bb_path_motd_file, "r");
	if (fp) {
		while ((c = getc(fp)) != EOF)
			putchar(c);
		fclose(fp);
	}
}

static void nonblock(int fd)
{
	fcntl(fd, F_SETFL, O_NONBLOCK | fcntl(fd, F_GETFL));
}

static void alarm_handler(int sig ATTRIBUTE_UNUSED)
{
	/* This is the escape hatch!  Poor serial line users and the like
	 * arrive here when their connection is broken.
	 * We don't want to block here */
	nonblock(1);
	nonblock(2);
	bb_info_msg("\r\nLogin timed out after %d seconds\r", TIMEOUT);
	exit(EXIT_SUCCESS);
}

int login_main(int argc, char **argv)
{
	enum {
		LOGIN_OPT_f = (1<<0),
		LOGIN_OPT_h = (1<<1),
		LOGIN_OPT_p = (1<<2),
	};
	char fromhost[512];
	char username[USERNAME_SIZE];
	const char *tmp;
	int amroot;
	unsigned opt;
	int count = 0;
	struct passwd *pw;
	char *opt_host = NULL;
	char *opt_user = NULL;
	USE_SELINUX(security_context_t user_sid = NULL;)

	username[0] = '\0';
	amroot = (getuid() == 0);
	signal(SIGALRM, alarm_handler);
	alarm(TIMEOUT);

	opt = getopt32(argc, argv, "f:h:p", &opt_user, &opt_host);
	if (opt & LOGIN_OPT_f) {
		if (!amroot)
			bb_error_msg_and_die("-f is for root only");
		safe_strncpy(username, opt_user, sizeof(username));
	}
	if (optind < argc) /* user from command line (getty) */
		safe_strncpy(username, argv[optind], sizeof(username));

	/* Let's find out and memorize our tty */
	if (!isatty(0) || !isatty(1) || !isatty(2))
		return EXIT_FAILURE;		/* Must be a terminal */
	safe_strncpy(full_tty, "UNKNOWN", sizeof(full_tty));
	tmp = ttyname(0);
	if (tmp) {
		safe_strncpy(full_tty, tmp, sizeof(full_tty));
		if (strncmp(full_tty, "/dev/", 5) == 0)
			short_tty = full_tty + 5;
	}

	read_or_build_utent(!amroot);

	if (opt_host) {
		USE_FEATURE_UTMP(
			safe_strncpy(utent.ut_host, opt_host, sizeof(utent.ut_host));
		)
		snprintf(fromhost, sizeof(fromhost)-1, " on '%.100s' from "
					"'%.200s'", short_tty, opt_host);
	}
	else
		snprintf(fromhost, sizeof(fromhost)-1, " on '%.100s'", short_tty);

	bb_setpgrp;

	openlog(applet_name, LOG_PID | LOG_CONS | LOG_NOWAIT, LOG_AUTH);

	while (1) {
		if (!username[0])
			get_username_or_die(username, sizeof(username));

		pw = getpwnam(username);
		if (!pw) {
			safe_strncpy(username, "UNKNOWN", sizeof(username));
			goto auth_failed;
		}

		if (pw->pw_passwd[0] == '!' || pw->pw_passwd[0] == '*')
			goto auth_failed;

		if (opt & LOGIN_OPT_f)
			break; /* -f USER: success without asking passwd */

		if (pw->pw_uid == 0 && !check_securetty())
			goto auth_failed;

		/* Don't check the password if password entry is empty (!) */
		if (!pw->pw_passwd[0])
			break;

		/* authorization takes place here */
		if (correct_password(pw))
			break;

auth_failed:
		opt &= ~LOGIN_OPT_f;
		bb_do_delay(FAIL_DELAY);
		puts("Login incorrect");
		if (++count == 3) {
			syslog(LOG_WARNING, "invalid password for '%s'%s",
						username, fromhost);
			return EXIT_FAILURE;
		}
		username[0] = '\0';
	}

	alarm(0);
	die_if_nologin_and_non_root(pw->pw_uid == 0);

	write_utent(username);

#ifdef CONFIG_SELINUX
	if (is_selinux_enabled()) {
		security_context_t old_tty_sid, new_tty_sid;

		if (get_default_context(username, NULL, &user_sid)) {
			bb_error_msg_and_die("cannot get SID for %s",
					username);
		}
		if (getfilecon(full_tty, &old_tty_sid) < 0) {
			bb_perror_msg_and_die("getfilecon(%s) failed",
					full_tty);
		}
		if (security_compute_relabel(user_sid, old_tty_sid,
					SECCLASS_CHR_FILE, &new_tty_sid) != 0) {
			bb_perror_msg_and_die("security_change_sid(%s) failed",
					full_tty);
		}
		if (setfilecon(full_tty, new_tty_sid) != 0) {
			bb_perror_msg_and_die("chsid(%s, %s) failed",
					full_tty, new_tty_sid);
		}
	}
#endif
	/* Try these, but don't complain if they fail.
	 * _f_chown is safe wrt race t=ttyname(0);...;chown(t); */
	fchown(0, pw->pw_uid, pw->pw_gid);
	fchmod(0, 0600);

	/* TODO: be nommu-friendly, use spawn? */
	if (ENABLE_LOGIN_SCRIPTS) {
		char *script = getenv("LOGIN_PRE_SUID_SCRIPT");
		if (script) {
			char *t_argv[2] = { script, NULL };
			switch (fork()) {
			case -1: break;
			case 0: /* child */
				xchdir("/");
				setenv("LOGIN_TTY", full_tty, 1);
				setenv("LOGIN_USER", pw->pw_name, 1);
				setenv("LOGIN_UID", utoa(pw->pw_uid), 1);
				setenv("LOGIN_GID", utoa(pw->pw_gid), 1);
				setenv("LOGIN_SHELL", pw->pw_shell, 1);
				execvp(script, t_argv);
				exit(1);
			default: /* parent */
				wait(NULL);
			}
		}
	}

	change_identity(pw);
	tmp = pw->pw_shell;
	if (!tmp || !*tmp)
		tmp = DEFAULT_SHELL;
	setup_environment(tmp, 1, !(opt & LOGIN_OPT_p), pw);

	motd();

	if (pw->pw_uid == 0)
		syslog(LOG_INFO, "root login%s", fromhost);
#ifdef CONFIG_SELINUX
	/* well, a simple setexeccon() here would do the job as well,
	 * but let's play the game for now */
	set_current_security_context(user_sid);
#endif

	// util-linux login also does:
	// /* start new session */
	// setsid();
	// /* TIOCSCTTY: steal tty from other process group */
	// if (ioctl(0, TIOCSCTTY, 1)) error_msg...

	/* set signals to defaults */
	signal(SIGALRM, SIG_DFL);
	/* Is this correct? This way user can ctrl-c out of /etc/profile,
	 * potentially creating security breach (tested with bash 3.0).
	 * But without this, bash 3.0 will not enable ctrl-c either.
	 * Maybe bash is buggy?
	 * Need to find out what standards say about /bin/login -
	 * should it leave SIGINT etc enabled or disabled? */
	signal(SIGINT, SIG_DFL);

	run_shell(tmp, 1, 0, 0);	/* exec the shell finally */

	return EXIT_FAILURE;
}
1	/* vi: set sw=4 ts=4: */
2	/*
3	* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
4	*/
5
6	#include "busybox.h"
7	#include <utmp.h>
8	#include <sys/resource.h>
9	#include <syslog.h>
10
11	#ifdef CONFIG_SELINUX
12	#include <selinux/selinux.h> /* for is_selinux_enabled() */
13	#include <selinux/get_context_list.h> /* for get_default_context() */
14	#include <selinux/flask.h> /* for security class definitions */
15	#include <errno.h>
16	#endif
17
18	enum {
19	TIMEOUT = 60,
20	EMPTY_USERNAME_COUNT = 10,
21	USERNAME_SIZE = 32,
22	TTYNAME_SIZE = 32,
23	};
24
25	static char full_tty[TTYNAME_SIZE];
26	static char* short_tty = full_tty;
27
28	#if ENABLE_FEATURE_UTMP
29	/* vv Taken from tinylogin utmp.c vv */
30	/*
31	* read_or_build_utent - see if utmp file is correct for this process
32	*
33	* System V is very picky about the contents of the utmp file
34	* and requires that a slot for the current process exist.
35	* The utmp file is scanned for an entry with the same process
36	* ID. If no entry exists the process exits with a message.
37	*
38	* The "picky" flag is for network and other logins that may
39	* use special flags. It allows the pid checks to be overridden.
40	* This means that getty should never invoke login with any
41	* command line flags.
42	*/
43
44	static struct utmp utent;
45
46	static void read_or_build_utent(int picky)
47	{
48	struct utmp *ut;
49	pid_t pid = getpid();
50
51	setutent();
52
53	/* First, try to find a valid utmp entry for this process. */
54	while ((ut = getutent()))
55	if (ut->ut_pid == pid && ut->ut_line[0] && ut->ut_id[0] &&
56	(ut->ut_type == LOGIN_PROCESS \|\| ut->ut_type == USER_PROCESS))
57	break;
58
59	/* If there is one, just use it, otherwise create a new one. */
60	if (ut) {
61	utent = *ut;
62	} else {
63	if (picky)
64	bb_error_msg_and_die("no utmp entry found");
65
66	memset(&utent, 0, sizeof(utent));
67	utent.ut_type = LOGIN_PROCESS;
68	utent.ut_pid = pid;
69	strncpy(utent.ut_line, short_tty, sizeof(utent.ut_line));
70	/* This one is only 4 chars wide. Try to fit something
71	* remotely meaningful by skipping "tty"... */
72	strncpy(utent.ut_id, short_tty + 3, sizeof(utent.ut_id));
73	strncpy(utent.ut_user, "LOGIN", sizeof(utent.ut_user));
74	utent.ut_time = time(NULL);
75	}
76	if (!picky) /* root login */
77	memset(utent.ut_host, 0, sizeof(utent.ut_host));
78	}
79
80	/*
81	* write_utent - put a USER_PROCESS entry in the utmp file
82	*
83	* write_utent changes the type of the current utmp entry to
84	* USER_PROCESS. the wtmp file will be updated as well.
85	*/
86	static void write_utent(const char *username)
87	{
88	utent.ut_type = USER_PROCESS;
89	strncpy(utent.ut_user, username, sizeof(utent.ut_user));
90	utent.ut_time = time(NULL);
91	/* other fields already filled in by read_or_build_utent above */
92	setutent();
93	pututline(&utent);
94	endutent();
95	#if ENABLE_FEATURE_WTMP
96	if (access(bb_path_wtmp_file, R_OK\|W_OK) == -1) {
97	close(creat(bb_path_wtmp_file, 0664));
98	}
99	updwtmp(bb_path_wtmp_file, &utent);
100	#endif
101	}
102	#else /* !ENABLE_FEATURE_UTMP */
103	static inline void read_or_build_utent(int ATTRIBUTE_UNUSED picky) {}
104	static inline void write_utent(const char ATTRIBUTE_UNUSED *username) {}
105	#endif /* !ENABLE_FEATURE_UTMP */
106
107	static void die_if_nologin_and_non_root(int amroot)
108	{
109	FILE *fp;
110	int c;
111
112	if (access(bb_path_nologin_file, F_OK))
113	return;
114
115	fp = fopen(bb_path_nologin_file, "r");
116	if (fp) {
117	while ((c = getc(fp)) != EOF)
118	putchar((c=='\n') ? '\r' : c);
119	fflush(stdout);
120	fclose(fp);
121	} else
122	puts("\r\nSystem closed for routine maintenance\r");
123	if (!amroot)
124	exit(1);
125	puts("\r\n[Disconnect bypassed -- root login allowed.]\r");
126	}
127
128	#if ENABLE_FEATURE_SECURETTY
129	static int check_securetty(void)
130	{
131	FILE *fp;
132	int i;
133	char buf[BUFSIZ];
134
135	fp = fopen(bb_path_securetty_file, "r");
136	if (!fp) {
137	/* A missing securetty file is not an error. */
138	return 1;
139	}
140	while (fgets(buf, sizeof(buf)-1, fp)) {
141	for (i = strlen(buf)-1; i>=0; --i) {
142	if (!isspace(buf[i]))
143	break;
144	}
145	buf[++i] = '\0';
146	if ((buf[0]=='\0') \|\| (buf[0]=='#'))
147	continue;
148	if (strcmp(buf, short_tty) == 0) {
149	fclose(fp);
150	return 1;
151	}
152	}
153	fclose(fp);
154	return 0;
155	}
156	#else
157	static inline int check_securetty(void) { return 1; }
158	#endif
159
160	static void get_username_or_die(char *buf, int size_buf)
161	{
162	int c, cntdown;
163	cntdown = EMPTY_USERNAME_COUNT;
164	prompt:
165	/* skip whitespace */
166	print_login_prompt();
167	do {
168	c = getchar();
169	if (c == EOF) exit(1);
170	if (c == '\n') {
171	if (!--cntdown) exit(1);
172	goto prompt;
173	}
174	} while (isspace(c));
175
176	*buf++ = c;
177	if (!fgets(buf, size_buf-2, stdin))
178	exit(1);
179	if (!strchr(buf, '\n'))
180	exit(1);
181	while (isgraph(*buf)) buf++;
182	*buf = '\0';
183	}
184
185	static void motd(void)
186	{
187	FILE *fp;
188	int c;
189
190	fp = fopen(bb_path_motd_file, "r");
191	if (fp) {
192	while ((c = getc(fp)) != EOF)
193	putchar(c);
194	fclose(fp);
195	}
196	}
197
198	static void nonblock(int fd)
199	{
200	fcntl(fd, F_SETFL, O_NONBLOCK \| fcntl(fd, F_GETFL));
201	}
202
203	static void alarm_handler(int sig ATTRIBUTE_UNUSED)
204	{
205	/* This is the escape hatch! Poor serial line users and the like
206	* arrive here when their connection is broken.
207	* We don't want to block here */
208	nonblock(1);
209	nonblock(2);
210	bb_info_msg("\r\nLogin timed out after %d seconds\r", TIMEOUT);
211	exit(EXIT_SUCCESS);
212	}
213
214	int login_main(int argc, char **argv)
215	{
216	enum {
217	LOGIN_OPT_f = (1<<0),
218	LOGIN_OPT_h = (1<<1),
219	LOGIN_OPT_p = (1<<2),
220	};
221	char fromhost[512];
222	char username[USERNAME_SIZE];
223	const char *tmp;
224	int amroot;
225	unsigned opt;
226	int count = 0;
227	struct passwd *pw;
228	char *opt_host = NULL;
229	char *opt_user = NULL;
230	USE_SELINUX(security_context_t user_sid = NULL;)
231
232	username[0] = '\0';
233	amroot = (getuid() == 0);
234	signal(SIGALRM, alarm_handler);
235	alarm(TIMEOUT);
236
237	opt = getopt32(argc, argv, "f:h:p", &opt_user, &opt_host);
238	if (opt & LOGIN_OPT_f) {
239	if (!amroot)
240	bb_error_msg_and_die("-f is for root only");
241	safe_strncpy(username, opt_user, sizeof(username));
242	}
243	if (optind < argc) /* user from command line (getty) */
244	safe_strncpy(username, argv[optind], sizeof(username));
245
246	/* Let's find out and memorize our tty */
247	if (!isatty(0) \|\| !isatty(1) \|\| !isatty(2))
248	return EXIT_FAILURE; /* Must be a terminal */
249	safe_strncpy(full_tty, "UNKNOWN", sizeof(full_tty));
250	tmp = ttyname(0);
251	if (tmp) {
252	safe_strncpy(full_tty, tmp, sizeof(full_tty));
253	if (strncmp(full_tty, "/dev/", 5) == 0)
254	short_tty = full_tty + 5;
255	}
256
257	read_or_build_utent(!amroot);
258
259	if (opt_host) {
260	USE_FEATURE_UTMP(
261	safe_strncpy(utent.ut_host, opt_host, sizeof(utent.ut_host));
262	)
263	snprintf(fromhost, sizeof(fromhost)-1, " on '%.100s' from "
264	"'%.200s'", short_tty, opt_host);
265	}
266	else
267	snprintf(fromhost, sizeof(fromhost)-1, " on '%.100s'", short_tty);
268
269	bb_setpgrp;
270
271	openlog(applet_name, LOG_PID \| LOG_CONS \| LOG_NOWAIT, LOG_AUTH);
272
273	while (1) {
274	if (!username[0])
275	get_username_or_die(username, sizeof(username));
276
277	pw = getpwnam(username);
278	if (!pw) {
279	safe_strncpy(username, "UNKNOWN", sizeof(username));
280	goto auth_failed;
281	}
282
283	if (pw->pw_passwd[0] == '!' \|\| pw->pw_passwd[0] == '*')
284	goto auth_failed;
285
286	if (opt & LOGIN_OPT_f)
287	break; /* -f USER: success without asking passwd */
288
289	if (pw->pw_uid == 0 && !check_securetty())
290	goto auth_failed;
291
292	/* Don't check the password if password entry is empty (!) */
293	if (!pw->pw_passwd[0])
294	break;
295
296	/* authorization takes place here */
297	if (correct_password(pw))
298	break;
299
300	auth_failed:
301	opt &= ~LOGIN_OPT_f;
302	bb_do_delay(FAIL_DELAY);
303	puts("Login incorrect");
304	if (++count == 3) {
305	syslog(LOG_WARNING, "invalid password for '%s'%s",
306	username, fromhost);
307	return EXIT_FAILURE;
308	}
309	username[0] = '\0';
310	}
311
312	alarm(0);
313	die_if_nologin_and_non_root(pw->pw_uid == 0);
314
315	write_utent(username);
316
317	#ifdef CONFIG_SELINUX
318	if (is_selinux_enabled()) {
319	security_context_t old_tty_sid, new_tty_sid;
320
321	if (get_default_context(username, NULL, &user_sid)) {
322	bb_error_msg_and_die("cannot get SID for %s",
323	username);
324	}
325	if (getfilecon(full_tty, &old_tty_sid) < 0) {
326	bb_perror_msg_and_die("getfilecon(%s) failed",
327	full_tty);
328	}
329	if (security_compute_relabel(user_sid, old_tty_sid,
330	SECCLASS_CHR_FILE, &new_tty_sid) != 0) {
331	bb_perror_msg_and_die("security_change_sid(%s) failed",
332	full_tty);
333	}
334	if (setfilecon(full_tty, new_tty_sid) != 0) {
335	bb_perror_msg_and_die("chsid(%s, %s) failed",
336	full_tty, new_tty_sid);
337	}
338	}
339	#endif
340	/* Try these, but don't complain if they fail.
341	* _f_chown is safe wrt race t=ttyname(0);...;chown(t); */
342	fchown(0, pw->pw_uid, pw->pw_gid);
343	fchmod(0, 0600);
344
345	/* TODO: be nommu-friendly, use spawn? */
346	if (ENABLE_LOGIN_SCRIPTS) {
347	char *script = getenv("LOGIN_PRE_SUID_SCRIPT");
348	if (script) {
349	char *t_argv[2] = { script, NULL };
350	switch (fork()) {
351	case -1: break;
352	case 0: /* child */
353	xchdir("/");
354	setenv("LOGIN_TTY", full_tty, 1);
355	setenv("LOGIN_USER", pw->pw_name, 1);
356	setenv("LOGIN_UID", utoa(pw->pw_uid), 1);
357	setenv("LOGIN_GID", utoa(pw->pw_gid), 1);
358	setenv("LOGIN_SHELL", pw->pw_shell, 1);
359	execvp(script, t_argv);
360	exit(1);
361	default: /* parent */
362	wait(NULL);
363	}
364	}
365	}
366
367	change_identity(pw);
368	tmp = pw->pw_shell;
369	if (!tmp \|\| !*tmp)
370	tmp = DEFAULT_SHELL;
371	setup_environment(tmp, 1, !(opt & LOGIN_OPT_p), pw);
372
373	motd();
374
375	if (pw->pw_uid == 0)
376	syslog(LOG_INFO, "root login%s", fromhost);
377	#ifdef CONFIG_SELINUX
378	/* well, a simple setexeccon() here would do the job as well,
379	* but let's play the game for now */
380	set_current_security_context(user_sid);
381	#endif
382
383	// util-linux login also does:
384	// /* start new session */
385	// setsid();
386	// /* TIOCSCTTY: steal tty from other process group */
387	// if (ioctl(0, TIOCSCTTY, 1)) error_msg...
388
389	/* set signals to defaults */
390	signal(SIGALRM, SIG_DFL);
391	/* Is this correct? This way user can ctrl-c out of /etc/profile,
392	* potentially creating security breach (tested with bash 3.0).
393	* But without this, bash 3.0 will not enable ctrl-c either.
394	* Maybe bash is buggy?
395	* Need to find out what standards say about /bin/login -
396	* should it leave SIGINT etc enabled or disabled? */
397	signal(SIGINT, SIG_DFL);
398
399	run_shell(tmp, 1, 0, 0); /* exec the shell finally */
400
401	return EXIT_FAILURE;
402	}