931c55f9e2
Double negatives are hard to grok. function old new delta login_main 986 988 +2 su_main 474 470 -4 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/1 up/down: 2/-4) Total: -2 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
129 lines
3.3 KiB
C
129 lines
3.3 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 (17 kb)"
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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:IF_SULOGIN(APPLET_NOEXEC(sulogin, sulogin, BB_DIR_SBIN, BB_SUID_DROP, sulogin))
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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 -p Start a login shell"
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//usage: "\n -t SEC 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 tsid;
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int timeout = 0;
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unsigned opts;
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struct passwd *pwd;
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const char *shell;
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/* Note: sulogin is not a suid app. It is meant to be run by init
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* for single user / emergency mode. init starts it as root.
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* Normal users (potentially malicious ones) can only run it under
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* their UID, therefore no paranoia here is warranted:
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* $LD_LIBRARY_PATH in env, TTY = /dev/sda
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* are no more dangerous here than in e.g. cp applet.
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*/
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logmode = LOGMODE_BOTH;
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openlog(applet_name, 0, LOG_AUTH);
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opts = getopt32(argv, "pt:+", &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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pwd = getpwuid(0);
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if (!pwd) {
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bb_simple_error_msg_and_die("no password entry for root");
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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 maintenance\n"
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"(or type Ctrl-D to continue): "
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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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/* util-linux 2.36.1 compat: no message */
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/*bb_simple_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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pause_after_failed_login();
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bb_simple_info_msg("Login incorrect");
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}
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/* util-linux 2.36.1 compat: no message */
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/*bb_simple_info_msg("starting shell for system maintenance");*/
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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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/* util-linux 2.36.1 compat: cd to root's HOME, set a few envvars */
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setup_environment(shell, 0
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+ SETUP_ENV_CHANGEENV_LOGNAME
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+ SETUP_ENV_CHDIR
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, pwd);
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// no SETUP_ENV_CLEARENV
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// SETUP_ENV_CHANGEENV_LOGNAME - set HOME, SHELL, USER,and LOGNAME
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// SETUP_ENV_CHDIR - cd to $HOME
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/* util-linux 2.36.1 compat: steal ctty if we don't have it yet
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* (yes, util-linux uses force=1) */
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tsid = tcgetsid(STDIN_FILENO);
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if (tsid < 0 || getpid() != tsid) {
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if (ioctl(STDIN_FILENO, TIOCSCTTY, /*force:*/ (long)1) != 0) {
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// bb_perror_msg("TIOCSCTTY1 tsid:%d", tsid);
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if (setsid() > 0) {
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// bb_error_msg("done setsid()");
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/* If it still does not work, ignore */
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if (ioctl(STDIN_FILENO, TIOCSCTTY, /*force:*/ (long)1) != 0) {
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// bb_perror_msg("TIOCSCTTY2 tsid:%d", tsid);
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}
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}
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}
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}
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/*
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* Note: login does this (should we do it too?):
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*/
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/*signal(SIGINT, SIG_DFL);*/
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/* Exec shell with no additional parameters. Never returns. */
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exec_shell(shell, /* -p? then shell is login:*/(opts & 1), NULL);
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}
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