123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128 |
- /* vi: set sw=4 ts=4: */
- /*
- * Mini sulogin implementation for busybox
- *
- * Licensed under GPLv2 or later, see file LICENSE in this source tree.
- */
- //config:config SULOGIN
- //config: bool "sulogin (18 kb)"
- //config: default y
- //config: select FEATURE_SYSLOG
- //config: help
- //config: sulogin is invoked when the system goes into single user
- //config: mode (this is done through an entry in inittab).
- //applet:IF_SULOGIN(APPLET_NOEXEC(sulogin, sulogin, BB_DIR_SBIN, BB_SUID_DROP, sulogin))
- //kbuild:lib-$(CONFIG_SULOGIN) += sulogin.o
- //usage:#define sulogin_trivial_usage
- //usage: "[-t N] [TTY]"
- //usage:#define sulogin_full_usage "\n\n"
- //usage: "Single user login\n"
- //usage: "\n -p Start a login shell"
- //usage: "\n -t SEC Timeout"
- #include "libbb.h"
- #include <syslog.h>
- int sulogin_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
- int sulogin_main(int argc UNUSED_PARAM, char **argv)
- {
- int tsid;
- int timeout = 0;
- unsigned opts;
- struct passwd *pwd;
- const char *shell;
- /* Note: sulogin is not a suid app. It is meant to be run by init
- * for single user / emergency mode. init starts it as root.
- * Normal users (potentially malicious ones) can only run it under
- * their UID, therefore no paranoia here is warranted:
- * $LD_LIBRARY_PATH in env, TTY = /dev/sda
- * are no more dangerous here than in e.g. cp applet.
- */
- logmode = LOGMODE_BOTH;
- openlog(applet_name, 0, LOG_AUTH);
- opts = getopt32(argv, "pt:+", &timeout);
- argv += optind;
- if (argv[0]) {
- close(0);
- close(1);
- dup(xopen(argv[0], O_RDWR));
- close(2);
- dup(0);
- }
- pwd = getpwuid(0);
- if (!pwd) {
- bb_simple_error_msg_and_die("no password entry for root");
- }
- while (1) {
- int r;
- r = ask_and_check_password_extended(pwd, timeout,
- "Give root password for maintenance\n"
- "(or type Ctrl-D to continue): "
- );
- if (r < 0) {
- /* ^D, ^C, timeout, or read error */
- /* util-linux 2.36.1 compat: no message */
- /*bb_simple_info_msg("normal startup");*/
- return 0;
- }
- if (r > 0) {
- break;
- }
- pause_after_failed_login();
- bb_simple_info_msg("Login incorrect");
- }
- /* util-linux 2.36.1 compat: no message */
- /*bb_simple_info_msg("starting shell for system maintenance");*/
- IF_SELINUX(renew_current_security_context());
- shell = getenv("SUSHELL");
- if (!shell)
- shell = getenv("sushell");
- if (!shell)
- shell = pwd->pw_shell;
- /* util-linux 2.36.1 compat: cd to root's HOME, set a few envvars */
- setup_environment(shell, 0
- + SETUP_ENV_CHANGEENV_LOGNAME
- + SETUP_ENV_CHDIR
- , pwd);
- // no SETUP_ENV_CLEARENV
- // SETUP_ENV_CHANGEENV_LOGNAME - set HOME, SHELL, USER,and LOGNAME
- // SETUP_ENV_CHDIR - cd to $HOME
- /* util-linux 2.36.1 compat: steal ctty if we don't have it yet
- * (yes, util-linux uses force=1) */
- tsid = tcgetsid(STDIN_FILENO);
- if (tsid < 0 || getpid() != tsid) {
- if (ioctl(STDIN_FILENO, TIOCSCTTY, /*force:*/ (long)1) != 0) {
- // bb_perror_msg("TIOCSCTTY1 tsid:%d", tsid);
- if (setsid() > 0) {
- // bb_error_msg("done setsid()");
- /* If it still does not work, ignore */
- if (ioctl(STDIN_FILENO, TIOCSCTTY, /*force:*/ (long)1) != 0) {
- // bb_perror_msg("TIOCSCTTY2 tsid:%d", tsid);
- }
- }
- }
- }
- /*
- * Note: login does this (should we do it too?):
- */
- /*signal(SIGINT, SIG_DFL);*/
- /* Exec shell with no additional parameters. Never returns. */
- exec_shell(shell, /* -p? then shell is login:*/(opts & 1), NULL);
- }
|