X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=loginutils%2Flogin.c;h=70e85625b2ab60848955c646da0cc1b7c4e40d2d;hb=f2cbb03a378aa48f2e08b64877d54da3fab4ea6a;hp=c05ec066aa2fc7a445575a1a21ddc11c70147b44;hpb=6bbd174593d1e116351a9402b5bd237afbe3cb89;p=oweals%2Fbusybox.git

diff --git a/loginutils/login.c b/loginutils/login.c
index c05ec066a..70e85625b 100644
--- a/loginutils/login.c
+++ b/loginutils/login.c
@@ -3,504 +3,515 @@
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */
 
-#include <fcntl.h>
-#include <signal.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
+#include "libbb.h"
 #include <syslog.h>
-#include <termios.h>
-#include <unistd.h>
 #include <utmp.h>
 #include <sys/resource.h>
-#include <sys/stat.h>
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <ctype.h>
-#include <time.h>
-
-#include "busybox.h"
-#ifdef CONFIG_SELINUX
+
+#if ENABLE_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
 
-#ifdef CONFIG_FEATURE_UTMP
-// import from utmp.c
-static void checkutmp(int picky);
-static void setutmp(const char *name, const char *line);
-/* Stuff global to this file */
-static struct utmp utent;
+#if ENABLE_PAM
+/* PAM may include <locale.h>. We may need to undefine bbox's stub define: */
+#undef setlocale
+/* For some obscure reason, PAM is not in pam/xxx, but in security/xxx.
+ * Apparently they like to confuse people. */
+#include <security/pam_appl.h>
+#include <security/pam_misc.h>
+static const struct pam_conv conv = {
+	misc_conv,
+	NULL
+};
 #endif
 
 enum {
 	TIMEOUT = 60,
 	EMPTY_USERNAME_COUNT = 10,
 	USERNAME_SIZE = 32,
+	TTYNAME_SIZE = 32,
 };
 
-static int check_nologin(int amroot);
+static char* short_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 void read_or_build_utent(struct utmp *utptr, int run_by_root)
+{
+	struct utmp *ut;
+	pid_t pid = getpid();
+
+	setutent();
+
+	/* First, try to find a valid utmp entry for this process.  */
+	/* If there is one, just use it.  */
+	while ((ut = getutent()) != NULL)
+		if (ut->ut_pid == pid && ut->ut_line[0] && ut->ut_id[0]
+		 && (ut->ut_type == LOGIN_PROCESS || ut->ut_type == USER_PROCESS)
+		) {
+			*utptr = *ut; /* struct copy */
+			if (run_by_root) /* why only for root? */
+				memset(utptr->ut_host, 0, sizeof(utptr->ut_host));
+			return;
+		}
+
+// Why? Do we require non-root to exec login from another
+// former login process (e.g. login shell)? Some login's have
+// login shells as children, so it won't work...
+//	if (!run_by_root)
+//		bb_error_msg_and_die("no utmp entry found");
+
+	/* Otherwise create a new one.  */
+	memset(utptr, 0, sizeof(*utptr));
+	utptr->ut_type = LOGIN_PROCESS;
+	utptr->ut_pid = pid;
+	strncpy(utptr->ut_line, short_tty, sizeof(utptr->ut_line));
+	/* This one is only 4 chars wide. Try to fit something
+	 * remotely meaningful by skipping "tty"... */
+	strncpy(utptr->ut_id, short_tty + 3, sizeof(utptr->ut_id));
+	strncpy(utptr->ut_user, "LOGIN", sizeof(utptr->ut_user));
+	utptr->ut_tv.tv_sec = time(NULL);
+}
+
+/*
+ * 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(struct utmp *utptr, const char *username)
+{
+	utptr->ut_type = USER_PROCESS;
+	strncpy(utptr->ut_user, username, sizeof(utptr->ut_user));
+	utptr->ut_tv.tv_sec = time(NULL);
+	/* other fields already filled in by read_or_build_utent above */
+	setutent();
+	pututline(utptr);
+	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, utptr);
+#endif
+}
+#else /* !ENABLE_FEATURE_UTMP */
+#define read_or_build_utent(utptr, run_by_root) ((void)0)
+#define write_utent(utptr, username) ((void)0)
+#endif /* !ENABLE_FEATURE_UTMP */
+
+#if ENABLE_FEATURE_NOLOGIN
+static void die_if_nologin(void)
+{
+	FILE *fp;
+	int c;
+	int empty = 1;
 
-#if defined CONFIG_FEATURE_SECURETTY
-static int check_tty(const char *tty);
+	fp = fopen_for_read("/etc/nologin");
+	if (!fp) /* assuming it does not exist */
+		return;
 
+	while ((c = getc(fp)) != EOF) {
+		if (c == '\n')
+			bb_putchar('\r');
+		bb_putchar(c);
+		empty = 0;
+	}
+	if (empty)
+		puts("\r\nSystem closed for routine maintenance\r");
+
+	fclose(fp);
+	fflush(NULL);
+	/* Users say that they do need this prior to exit: */
+	tcdrain(STDOUT_FILENO);
+	exit(EXIT_FAILURE);
+}
 #else
-static inline int check_tty(const char *tty) { return 1; }
+static ALWAYS_INLINE void die_if_nologin(void) {}
+#endif
 
+#if ENABLE_FEATURE_SECURETTY && !ENABLE_PAM
+static int check_securetty(void)
+{
+	char *buf = (char*)"/etc/securetty"; /* any non-NULL is ok */
+	parser_t *parser = config_open2("/etc/securetty", fopen_for_read);
+	while (config_read(parser, &buf, 1, 1, "# \t", PARSE_NORMAL)) {
+		if (strcmp(buf, short_tty) == 0)
+			break;
+		buf = NULL;
+	}
+	config_close(parser);
+	/* buf != NULL here if config file was not found, empty
+	 * or line was found which equals short_tty */
+	return buf != NULL;
+}
+#else
+static ALWAYS_INLINE int check_securetty(void) { return 1; }
 #endif
 
-static int is_my_tty(const char *tty);
-static int login_prompt(char *buf_name);
-static void motd(void);
+#if ENABLE_SELINUX
+static void initselinux(char *username, char *full_tty,
+						security_context_t *user_sid)
+{
+	security_context_t old_tty_sid, new_tty_sid;
 
+	if (!is_selinux_enabled())
+		return;
 
-static void alarm_handler(int sig ATTRIBUTE_UNUSED)
+	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
+
+#if ENABLE_LOGIN_SCRIPTS
+static void run_login_script(struct passwd *pw, char *full_tty)
+{
+	char *t_argv[2];
+
+	t_argv[0] = getenv("LOGIN_PRE_SUID_SCRIPT");
+	if (t_argv[0]) {
+		t_argv[1] = NULL;
+		xsetenv("LOGIN_TTY", full_tty);
+		xsetenv("LOGIN_USER", pw->pw_name);
+		xsetenv("LOGIN_UID", utoa(pw->pw_uid));
+		xsetenv("LOGIN_GID", utoa(pw->pw_gid));
+		xsetenv("LOGIN_SHELL", pw->pw_shell);
+		spawn_and_wait(t_argv);	/* NOMMU-friendly */
+		unsetenv("LOGIN_TTY");
+		unsetenv("LOGIN_USER");
+		unsetenv("LOGIN_UID");
+		unsetenv("LOGIN_GID");
+		unsetenv("LOGIN_SHELL");
+	}
+}
+#else
+void run_login_script(struct passwd *pw, char *full_tty);
+#endif
+
+static void get_username_or_die(char *buf, int size_buf)
 {
-	fprintf(stderr, "\r\nLogin timed out after %s seconds\r\n", TIMEOUT);
-	exit(EXIT_SUCCESS);
+	int c, cntdown;
+
+	cntdown = EMPTY_USERNAME_COUNT;
+ prompt:
+	print_login_prompt();
+	/* skip whitespace */
+	do {
+		c = getchar();
+		if (c == EOF)
+			exit(EXIT_FAILURE);
+		if (c == '\n') {
+			if (!--cntdown)
+				exit(EXIT_FAILURE);
+			goto prompt;
+		}
+	} while (isspace(c)); /* maybe isblank? */
+
+	*buf++ = c;
+	if (!fgets(buf, size_buf-2, stdin))
+		exit(EXIT_FAILURE);
+	if (!strchr(buf, '\n'))
+		exit(EXIT_FAILURE);
+	while ((unsigned char)*buf > ' ')
+		buf++;
+	*buf = '\0';
 }
 
+static void motd(void)
+{
+	int fd;
 
-int login_main(int argc, char **argv)
+	fd = open(bb_path_motd_file, O_RDONLY);
+	if (fd >= 0) {
+		fflush(stdout);
+		bb_copyfd_eof(fd, STDOUT_FILENO);
+		close(fd);
+	}
+}
+
+static void alarm_handler(int sig UNUSED_PARAM)
 {
-	char tty[BUFSIZ];
-	char full_tty[200];
-	char fromhost[512];
+	/* 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 */
+	ndelay_on(1);
+	printf("\r\nLogin timed out after %d seconds\r\n", TIMEOUT);
+	fflush(stdout);
+	/* unix API is brain damaged regarding O_NONBLOCK,
+	 * we should undo it, or else we can affect other processes */
+	ndelay_off(1);
+	_exit(EXIT_SUCCESS);
+}
+
+int login_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int login_main(int argc UNUSED_PARAM, char **argv)
+{
+	enum {
+		LOGIN_OPT_f = (1<<0),
+		LOGIN_OPT_h = (1<<1),
+		LOGIN_OPT_p = (1<<2),
+	};
+	char *fromhost;
 	char username[USERNAME_SIZE];
 	const char *tmp;
-	int amroot;
-	int flag;
-	int failed;
+	int run_by_root;
+	unsigned opt;
 	int count = 0;
-	struct passwd *pw, pw_copy;
-#ifdef CONFIG_WHEEL_GROUP
-	struct group *grp;
-#endif
-	int opt_preserve = 0;
-	int opt_fflag = 0;
-	char *opt_host = 0;
-	int alarmstarted = 0;
-#ifdef CONFIG_SELINUX
-	security_context_t user_sid = NULL;
+	struct passwd *pw;
+	char *opt_host = opt_host; /* for compiler */
+	char *opt_user = opt_user; /* for compiler */
+	char *full_tty;
+	IF_SELINUX(security_context_t user_sid = NULL;)
+	IF_FEATURE_UTMP(struct utmp utent;)
+#if ENABLE_PAM
+	int pamret;
+	pam_handle_t *pamh;
+	const char *pamuser;
+	const char *failed_msg;
+	struct passwd pwdstruct;
+	char pwdbuf[256];
 #endif
 
 	username[0] = '\0';
-	amroot = (getuid() == 0);
 	signal(SIGALRM, alarm_handler);
 	alarm(TIMEOUT);
-	alarmstarted = 1;
-
-	while ((flag = getopt(argc, argv, "f:h:p")) != EOF) {
-		switch (flag) {
-		case 'p':
-			opt_preserve = 1;
-			break;
-		case 'f':
-			/*
-			 * username must be a separate token
-			 * (-f root, *NOT* -froot). --marekm
-			 */
-			if (optarg != argv[optind-1])
-				bb_show_usage();
 
-			if (!amroot)		/* Auth bypass only if real UID is zero */
-				bb_error_msg_and_die("-f permission denied");
-
-			safe_strncpy(username, optarg, USERNAME_SIZE);
-			opt_fflag = 1;
-			break;
-		case 'h':
-			opt_host = optarg;
-			break;
-		default:
-			bb_show_usage();
-		}
+	/* More of suid paranoia if called by non-root: */
+	/* Clear dangerous stuff, set PATH */
+	run_by_root = !sanitize_env_if_suid();
+
+	/* Mandatory paranoia for suid applet:
+	 * ensure that fd# 0,1,2 are opened (at least to /dev/null)
+	 * and any extra open fd's are closed.
+	 * (The name of the function is misleading. Not daemonizing here.) */
+	bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE | DAEMON_CLOSE_EXTRA_FDS, NULL);
+
+	opt = getopt32(argv, "f:h:p", &opt_user, &opt_host);
+	if (opt & LOGIN_OPT_f) {
+		if (!run_by_root)
+			bb_error_msg_and_die("-f is for root only");
+		safe_strncpy(username, opt_user, sizeof(username));
 	}
+	argv += optind;
+	if (argv[0]) /* user from command line (getty) */
+		safe_strncpy(username, argv[0], sizeof(username));
 
-	if (optind < argc)             /* user from command line (getty) */
-		safe_strncpy(username, argv[optind], USERNAME_SIZE);
-
-	if (!isatty(0) || !isatty(1) || !isatty(2))
+	/* Let's find out and memorize our tty */
+	if (!isatty(STDIN_FILENO) || !isatty(STDOUT_FILENO) || !isatty(STDERR_FILENO))
 		return EXIT_FAILURE;		/* Must be a terminal */
-
-#ifdef CONFIG_FEATURE_UTMP
-	checkutmp(!amroot);
-#endif
-
-	tmp = ttyname(0);
-	if (tmp && (strncmp(tmp, "/dev/", 5) == 0))
-		safe_strncpy(tty, tmp + 5, sizeof(tty));
-	else if (tmp && *tmp == '/')
-		safe_strncpy(tty, tmp, sizeof(tty));
-	else
-		safe_strncpy(tty, "UNKNOWN", sizeof(tty));
-
-#ifdef CONFIG_FEATURE_UTMP
-	if (amroot)
-		memset(utent.ut_host, 0, sizeof(utent.ut_host));
-#endif
-
-	if (opt_host) {
-#ifdef CONFIG_FEATURE_UTMP
-		safe_strncpy(utent.ut_host, opt_host, sizeof(utent.ut_host));
-#endif
-		snprintf(fromhost, sizeof(fromhost)-1, " on `%.100s' from "
-					"`%.200s'", tty, opt_host);
+	full_tty = xmalloc_ttyname(STDIN_FILENO);
+	if (!full_tty)
+		full_tty = xstrdup("UNKNOWN");
+	short_tty = full_tty;
+	if (strncmp(full_tty, "/dev/", 5) == 0)
+		short_tty += 5;
+
+	read_or_build_utent(&utent, run_by_root);
+
+	if (opt & LOGIN_OPT_h) {
+		IF_FEATURE_UTMP(safe_strncpy(utent.ut_host, opt_host, sizeof(utent.ut_host));)
+		fromhost = xasprintf(" on '%s' from '%s'", short_tty, opt_host);
+	} else {
+		fromhost = xasprintf(" on '%s'", short_tty);
 	}
-	else
-		snprintf(fromhost, sizeof(fromhost)-1, " on `%.100s'", tty);
 
-	bb_setpgrp;
+	/* Was breaking "login <username>" from shell command line: */
+	/*bb_setpgrp();*/
 
-	openlog(bb_applet_name, LOG_PID | LOG_CONS | LOG_NOWAIT, LOG_AUTH);
+	openlog(applet_name, LOG_PID | LOG_CONS, LOG_AUTH);
 
 	while (1) {
-		failed = 0;
+		/* flush away any type-ahead (as getty does) */
+		ioctl(0, TCFLSH, TCIFLUSH);
 
 		if (!username[0])
-			if (!login_prompt(username))
-				return EXIT_FAILURE;
+			get_username_or_die(username, sizeof(username));
 
-		if (!alarmstarted && (TIMEOUT > 0)) {
-			alarm(TIMEOUT);
-			alarmstarted = 1;
+#if ENABLE_PAM
+		pamret = pam_start("login", username, &conv, &pamh);
+		if (pamret != PAM_SUCCESS) {
+			failed_msg = "start";
+			goto pam_auth_failed;
 		}
-
+		/* set TTY (so things like securetty work) */
+		pamret = pam_set_item(pamh, PAM_TTY, short_tty);
+		if (pamret != PAM_SUCCESS) {
+			failed_msg = "set_item(TTY)";
+			goto pam_auth_failed;
+		}
+		pamret = pam_authenticate(pamh, 0);
+		if (pamret != PAM_SUCCESS) {
+			failed_msg = "authenticate";
+			goto pam_auth_failed;
+			/* TODO: or just "goto auth_failed"
+			 * since user seems to enter wrong password
+			 * (in this case pamret == 7)
+			 */
+		}
+		/* check that the account is healthy */
+		pamret = pam_acct_mgmt(pamh, 0);
+		if (pamret != PAM_SUCCESS) {
+			failed_msg = "acct_mgmt";
+			goto pam_auth_failed;
+		}
+		/* read user back */
+		pamuser = NULL;
+		/* gcc: "dereferencing type-punned pointer breaks aliasing rules..."
+		 * thus we cast to (void*) */
+		if (pam_get_item(pamh, PAM_USER, (void*)&pamuser) != PAM_SUCCESS) {
+			failed_msg = "get_item(USER)";
+			goto pam_auth_failed;
+		}
+		if (!pamuser || !pamuser[0])
+			goto auth_failed;
+		safe_strncpy(username, pamuser, sizeof(username));
+		/* Don't use "pw = getpwnam(username);",
+		 * PAM is said to be capable of destroying static storage
+		 * used by getpwnam(). We are using safe(r) function */
+		pw = NULL;
+		getpwnam_r(username, &pwdstruct, pwdbuf, sizeof(pwdbuf), &pw);
+		if (!pw)
+			goto auth_failed;
+		pamret = pam_open_session(pamh, 0);
+		if (pamret != PAM_SUCCESS) {
+			failed_msg = "open_session";
+			goto pam_auth_failed;
+		}
+		pamret = pam_setcred(pamh, PAM_ESTABLISH_CRED);
+		if (pamret != PAM_SUCCESS) {
+			failed_msg = "setcred";
+			goto pam_auth_failed;
+		}
+		break; /* success, continue login process */
+
+ pam_auth_failed:
+		/* syslog, because we don't want potential attacker
+		 * to know _why_ login failed */
+		syslog(LOG_WARNING, "pam_%s call failed: %s (%d)", failed_msg,
+					pam_strerror(pamh, pamret), pamret);
+		safe_strncpy(username, "UNKNOWN", sizeof(username));
+#else /* not PAM */
 		pw = getpwnam(username);
 		if (!pw) {
-			pw_copy.pw_name   = "UNKNOWN";
-			pw_copy.pw_passwd = "!";
-			opt_fflag = 0;
-			failed = 1;
-		} else
-			pw_copy = *pw;
-
-		pw = &pw_copy;
+			strcpy(username, "UNKNOWN");
+			goto fake_it;
+		}
 
-		if ((pw->pw_passwd[0] == '!') || (pw->pw_passwd[0] == '*'))
-			failed = 1;
+		if (pw->pw_passwd[0] == '!' || pw->pw_passwd[0] == '*')
+			goto auth_failed;
 
-		if (opt_fflag) {
-			opt_fflag = 0;
-			goto auth_ok;
-		}
+		if (opt & LOGIN_OPT_f)
+			break; /* -f USER: success without asking passwd */
 
-		if (!failed && (pw->pw_uid == 0) && (!check_tty(tty)))
-			failed = 1;
+		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])
-			goto auth_ok;
-
+			break;
+ fake_it:
 		/* authorization takes place here */
 		if (correct_password(pw))
-			goto auth_ok;
-
-		failed = 1;
-
-auth_ok:
-		if (!failed)
 			break;
-
+#endif /* ENABLE_PAM */
+ auth_failed:
+		opt &= ~LOGIN_OPT_f;
 		bb_do_delay(FAIL_DELAY);
+		/* TODO: doesn't sound like correct English phrase to me */
 		puts("Login incorrect");
-		username[0] = 0;
 		if (++count == 3) {
-			syslog(LOG_WARNING, "invalid password for `%s'%s", pw->pw_name, fromhost);
+			syslog(LOG_WARNING, "invalid password for '%s'%s",
+						username, fromhost);
 			return EXIT_FAILURE;
 		}
-	}
+		username[0] = '\0';
+	} /* while (1) */
 
 	alarm(0);
-	if (check_nologin(pw->pw_uid == 0))
-		return EXIT_FAILURE;
+	/* We can ignore /etc/nologin if we are logging in as root,
+	 * it doesn't matter whether we are run by root or not */
+	if (pw->pw_uid != 0)
+		die_if_nologin();
 
-#ifdef CONFIG_FEATURE_UTMP
-	setutmp(username, tty);
-#endif
+	write_utent(&utent, username);
 
-	if (*tty != '/')
-		snprintf(full_tty, sizeof(full_tty)-1, "/dev/%s", tty);
-	else
-		safe_strncpy(full_tty, tty, sizeof(full_tty)-1);
+	IF_SELINUX(initselinux(username, full_tty, &user_sid));
 
-#ifdef CONFIG_SELINUX
-	if (is_selinux_enabled()) {
-		security_context_t old_tty_sid, new_tty_sid;
+	/* 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);
 
-		if (get_default_context(username, NULL, &user_sid)) {
-			bb_error_msg_and_die("unable to get SID for %s",
-					username);
-		}
-		if (getfilecon(full_tty, &old_tty_sid) < 0) {
-			bb_perror_msg_and_die("getfilecon(%.100s) 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(%.100s) failed",
-					full_tty);
-		}
-		if (setfilecon(full_tty, new_tty_sid) != 0) {
-			bb_perror_msg_and_die("chsid(%.100s, %s) failed",
-					full_tty, new_tty_sid);
-		}
-	}
-#endif
-	if (!is_my_tty(full_tty))
-		syslog(LOG_ERR, "unable to determine TTY name, got %s", full_tty);
-
-	/* Try these, but don't complain if they fail
-	 * (for example when the root fs is read only) */
-	chown(full_tty, pw->pw_uid, pw->pw_gid);
-	chmod(full_tty, 0600);
-
-	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);
-			}
-		}
-	}
+	/* We trust environment only if we run by root */
+	if (ENABLE_LOGIN_SCRIPTS && run_by_root)
+		run_login_script(pw, full_tty);
 
 	change_identity(pw);
 	tmp = pw->pw_shell;
 	if (!tmp || !*tmp)
 		tmp = DEFAULT_SHELL;
-	setup_environment(tmp, 1, !opt_preserve, pw);
+	/* setup_environment params: shell, clear_env, change_env, pw */
+	setup_environment(tmp, !(opt & LOGIN_OPT_p), 1, pw);
 
 	motd();
-	signal(SIGALRM, SIG_DFL);	/* default alarm signal */
 
 	if (pw->pw_uid == 0)
-		syslog(LOG_INFO, "root login %s", fromhost);
-#ifdef CONFIG_SELINUX
+		syslog(LOG_INFO, "root login%s", fromhost);
+
 	/* 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
-	run_shell(tmp, 1, 0, 0);	/* exec the shell finally. */
-
-	return EXIT_FAILURE;
-}
-
-
-static int login_prompt(char *buf_name)
-{
-	char buf[1024];
-	char *sp, *ep;
-	int i;
-
-	for (i=0; i<EMPTY_USERNAME_COUNT; i++) {
-		print_login_prompt();
-
-		if (!fgets(buf, sizeof(buf)-1, stdin))
-			return 0;
-
-		if (!strchr(buf, '\n'))
-			return 0;
-
-		for (sp = buf; isspace(*sp); sp++) { }
-		for (ep = sp; isgraph(*ep); ep++) { }
-
-		*ep = '\0';
-		safe_strncpy(buf_name, sp, USERNAME_SIZE);
-		if (buf_name[0])
-			return 1;
-	}
-	return 0;
-}
-
-
-static int check_nologin(int amroot)
-{
-	if (access(bb_path_nologin_file, F_OK) == 0) {
-		FILE *fp;
-		int c;
-
-		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)
-			return 1;
-
-		puts("\r\n[Disconnect bypassed -- root login allowed.]\r");
-	}
-	return 0;
-}
-
-#ifdef CONFIG_FEATURE_SECURETTY
-
-static int check_tty(const char *tty)
-{
-	FILE *fp;
-	int i;
-	char buf[BUFSIZ];
-
-	fp = fopen(bb_path_securetty_file, "r");
-	if (fp) {
-		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, tty)== 0) {
-				fclose(fp);
-				return 1;
-			}
-		}
-		fclose(fp);
-		return 0;
-	}
-	/* A missing securetty file is not an error. */
-	return 1;
-}
-
-#endif
-
-/* returns 1 if true */
-static int is_my_tty(const char *tty)
-{
-	struct stat by_name, by_fd;
-
-	if (stat(tty, &by_name) || fstat(0, &by_fd))
-		return 0;
-
-	if (by_name.st_rdev != by_fd.st_rdev)
-		return 0;
-	else
-		return 1;
-}
-
-
-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);
-	}
-}
-
-
-#ifdef CONFIG_FEATURE_UTMP
-// vv  Taken from tinylogin utmp.c  vv
-
-#define	NO_UTENT \
-	"No utmp entry.  You must exec \"login\" from the lowest level \"sh\""
-#define	NO_TTY \
-	"Unable to determine your tty name."
-
-/*
- * checkutmp - 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 void checkutmp(int picky)
-{
-	char *line;
-	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 {
-		time_t t_tmp;
-		
-		if (picky) {
-			puts(NO_UTENT);
-			exit(1);
-		}
-		line = ttyname(0);
-		if (!line) {
-			puts(NO_TTY);
-			exit(1);
-		}
-		if (strncmp(line, "/dev/", 5) == 0)
-			line += 5;
-		memset(&utent, 0, sizeof(utent));
-		utent.ut_type = LOGIN_PROCESS;
-		utent.ut_pid = pid;
-		strncpy(utent.ut_line, line, sizeof(utent.ut_line));
-		/* XXX - assumes /dev/tty?? */
-		strncpy(utent.ut_id, utent.ut_line + 3, sizeof(utent.ut_id));
-		strncpy(utent.ut_user, "LOGIN", sizeof(utent.ut_user));
-		t_tmp = (time_t)utent.ut_time;
-		time(&t_tmp);
-	}
-}
-
-/*
- * setutmp - put a USER_PROCESS entry in the utmp file
- *
- *	setutmp changes the type of the current utmp entry to
- *	USER_PROCESS.  the wtmp file will be updated as well.
- */
-
-static void setutmp(const char *name, const char *line ATTRIBUTE_UNUSED)
-{
-	time_t t_tmp = (time_t)utent.ut_time;
-
-	utent.ut_type = USER_PROCESS;
-	strncpy(utent.ut_user, name, sizeof(utent.ut_user));
-	time(&t_tmp);
-	/* other fields already filled in by checkutmp above */
-	setutent();
-	pututline(&utent);
-	endutent();
-#ifdef CONFIG_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
+	IF_SELINUX(set_current_security_context(user_sid);)
+
+	// util-linux login also does:
+	// /* start new session */
+	// setsid();
+	// /* TIOCSCTTY: steal tty from other process group */
+	// if (ioctl(0, TIOCSCTTY, 1)) error_msg...
+	// BBox login used to do this (see above):
+	// bb_setpgrp();
+	// If this stuff is really needed, add it and explain why!
+
+	/* Set signals to defaults */
+	/* Non-ignored signals revert to SIG_DFL on exec anyway */
+	/*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 we leave SIGINT etc enabled or disabled? */
+	signal(SIGINT, SIG_DFL);
+
+	/* Exec login shell with no additional parameters */
+	run_shell(tmp, 1, NULL, NULL);
+
+	/* return EXIT_FAILURE; - not reached */
 }
-#endif /* CONFIG_FEATURE_UTMP */