| /* 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" |
| //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(sulogin, BB_DIR_SBIN, BB_SUID_DROP)) |
| |
| //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 -t N 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 timeout = 0; |
| 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 malisious 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); |
| |
| getopt32(argv, "t:+", &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_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 system maintenance\n" |
| "(or type Control-D for normal startup):" |
| ); |
| if (r < 0) { |
| /* ^D, ^C, timeout, or read error */ |
| bb_error_msg("normal startup"); |
| return 0; |
| } |
| if (r > 0) { |
| break; |
| } |
| bb_do_delay(LOGIN_FAIL_DELAY); |
| bb_error_msg("Login incorrect"); |
| } |
| |
| bb_error_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; |
| |
| /* Exec login shell with no additional parameters. Never returns. */ |
| run_shell(shell, 1, NULL); |
| } |