100 lines
2.2 KiB
C
100 lines
2.2 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Mini sulogin implementation for busybox
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*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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//config:config SULOGIN
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//config: bool "sulogin"
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//config: default y
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//config: select FEATURE_SYSLOG
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//config: help
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//config: sulogin is invoked when the system goes into single user
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//config: mode (this is done through an entry in inittab).
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//applet:/* Needs to be run by root or be suid root - needs to change uid and gid: */
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//applet:IF_SULOGIN(APPLET(sulogin, BB_DIR_SBIN, BB_SUID_DROP))
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//kbuild:lib-$(CONFIG_SULOGIN) += sulogin.o
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//usage:#define sulogin_trivial_usage
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//usage: "[-t N] [TTY]"
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//usage:#define sulogin_full_usage "\n\n"
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//usage: "Single user login\n"
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//usage: "\n -t N Timeout"
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#include "libbb.h"
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#include <syslog.h>
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int sulogin_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int sulogin_main(int argc UNUSED_PARAM, char **argv)
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{
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int timeout = 0;
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struct passwd *pwd;
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const char *shell;
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logmode = LOGMODE_BOTH;
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openlog(applet_name, 0, LOG_AUTH);
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opt_complementary = "t+"; /* -t N */
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getopt32(argv, "t:", &timeout);
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argv += optind;
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if (argv[0]) {
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close(0);
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close(1);
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dup(xopen(argv[0], O_RDWR));
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close(2);
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dup(0);
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}
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/* Malicious use like "sulogin /dev/sda"? */
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if (!isatty(0) || !isatty(1) || !isatty(2)) {
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logmode = LOGMODE_SYSLOG;
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bb_error_msg_and_die("not a tty");
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}
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/* Clear dangerous stuff, set PATH */
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sanitize_env_if_suid();
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pwd = getpwuid(0);
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if (!pwd) {
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goto auth_error;
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}
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while (1) {
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int r;
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r = ask_and_check_password_extended(pwd, timeout,
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"Give root password for system maintenance\n"
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"(or type Control-D for normal startup):"
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);
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if (r < 0) {
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/* ^D, ^C, timeout, or read error */
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bb_info_msg("Normal startup");
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return 0;
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}
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if (r > 0) {
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break;
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}
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bb_do_delay(LOGIN_FAIL_DELAY);
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bb_info_msg("Login incorrect");
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}
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bb_info_msg("System Maintenance Mode");
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IF_SELINUX(renew_current_security_context());
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shell = getenv("SUSHELL");
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if (!shell)
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shell = getenv("sushell");
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if (!shell)
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shell = pwd->pw_shell;
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/* Exec login shell with no additional parameters. Never returns. */
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run_shell(shell, 1, NULL, NULL);
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auth_error:
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bb_error_msg_and_die("no password entry for root");
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}
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