source: MondoRescue/branches/stable/mindi-busybox/loginutils/sulogin.c@ 1770

/* vi: set sw=4 ts=4: */
/*
 * Mini sulogin implementation for busybox
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include <syslog.h>

#include "libbb.h"

static const char *const forbid[] = {
    "ENV",
    "BASH_ENV",
    "HOME",
    "IFS",
    "PATH",
    "SHELL",
    "LD_LIBRARY_PATH",
    "LD_PRELOAD",
    "LD_TRACE_LOADED_OBJECTS",
    "LD_BIND_NOW",
    "LD_AOUT_LIBRARY_PATH",
    "LD_AOUT_PRELOAD",
    "LD_NOWARN",
    "LD_KEEPDIR",
    (char *) 0
};


static void catchalarm(int ATTRIBUTE_UNUSED junk)
{
    exit(EXIT_FAILURE);
}


int sulogin_main(int argc, char **argv);
int sulogin_main(int argc, char **argv)
{
    char *cp;
    int timeout = 0;
    char *timeout_arg;
    const char *const *p;
    struct passwd *pwd;
    const char *shell;
#if ENABLE_FEATURE_SHADOWPASSWDS
    /* Using _r function to avoid pulling in static buffers */
    char buffer[256];
    struct spwd spw;
    struct spwd *result;
#endif

    logmode = LOGMODE_BOTH;
    openlog(applet_name, 0, LOG_AUTH);

    if (getopt32(argv, "t:", &timeout_arg)) {
        timeout = xatoi_u(timeout_arg);
    }

    if (argv[optind]) {
        close(0);
        close(1);
        dup(xopen(argv[optind], O_RDWR));
        close(2);
        dup(0);
    }

    if (!isatty(0) || !isatty(1) || !isatty(2)) {
        logmode = LOGMODE_SYSLOG;
        bb_error_msg_and_die("not a tty");
    }

    /* Clear out anything dangerous from the environment */
    for (p = forbid; *p; p++)
        unsetenv(*p);

    signal(SIGALRM, catchalarm);

    pwd = getpwuid(0);
    if (!pwd) {
        goto auth_error;
    }

#if ENABLE_FEATURE_SHADOWPASSWDS
    if (getspnam_r(pwd->pw_name, &spw, buffer, sizeof(buffer), &result)) {
        goto auth_error;
    }
    pwd->pw_passwd = spw.sp_pwdp;
#endif

    while (1) {
        /* cp points to a static buffer that is zeroed every time */
        cp = bb_askpass(timeout,
                "Give root password for system maintenance\n"
                "(or type Control-D for normal startup):");

        if (!cp || !*cp) {
            bb_info_msg("Normal startup");
            return 0;
        }
        if (strcmp(pw_encrypt(cp, pwd->pw_passwd), pwd->pw_passwd) == 0) {
            break;
        }
        bb_do_delay(FAIL_DELAY);
        bb_error_msg("login incorrect");
    }
    memset(cp, 0, strlen(cp));
    signal(SIGALRM, SIG_DFL);

    bb_info_msg("System Maintenance Mode");

    USE_SELINUX(renew_current_security_context());

    shell = getenv("SUSHELL");
    if (!shell) shell = getenv("sushell");
    if (!shell) {
        shell = "/bin/sh";
        if (pwd->pw_shell[0])
            shell = pwd->pw_shell;
    }
    run_shell(shell, 1, 0, 0);
    /* never returns */

auth_error:
    bb_error_msg_and_die("no password entry for 'root'");
}