source: MondoRescue/branches/3.2/mindi-busybox/loginutils/sulogin.c@ 3232

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

//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>

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


int sulogin_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int sulogin_main(int argc UNUSED_PARAM, char **argv)
{
    char *cp;
    int timeout = 0;
    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;
#endif

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

    opt_complementary = "t+"; /* -t N */
    getopt32(argv, "t:", &timeout);
    argv += optind;

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

    /* Malicious use like "sulogin /dev/sda"? */
    if (!isatty(0) || !isatty(1) || !isatty(2)) {
        logmode = LOGMODE_SYSLOG;
        bb_error_msg_and_die("not a tty");
    }

    /* Clear dangerous stuff, set PATH */
    sanitize_env_if_suid();

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

#if ENABLE_FEATURE_SHADOWPASSWDS
    {
        /* getspnam_r may return 0 yet set result to NULL.
         * At least glibc 2.4 does this. Be extra paranoid here. */
        struct spwd *result = NULL;
        int r = getspnam_r(pwd->pw_name, &spw, buffer, sizeof(buffer), &result);
        if (r || !result) {
            goto auth_error;
        }
        pwd->pw_passwd = result->sp_pwdp;
    }
#endif

    while (1) {
        char *encrypted;
        int r;

        /* cp points to a static buffer that is zeroed every time */
        cp = bb_ask(STDIN_FILENO, 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;
        }
        encrypted = pw_encrypt(cp, pwd->pw_passwd, 1);
        r = strcmp(encrypted, pwd->pw_passwd);
        free(encrypted);
        if (r == 0) {
            break;
        }
        bb_do_delay(LOGIN_FAIL_DELAY);
        bb_info_msg("Login incorrect");
    }
    memset(cp, 0, strlen(cp));
//  signal(SIGALRM, SIG_DFL);

    bb_info_msg("System Maintenance Mode");

    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, NULL);

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