xref: /freebsd/libexec/ulog-helper/ulog-helper.c (revision 2208eadf43351a36e70377f3e796daf76a06b8d9)

/*-
 * Copyright (c) 2009 Ed Schouten <ed@FreeBSD.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <pwd.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <ulog.h>

/*
 * This setuid helper utility writes user login records to disk.
 * Unprivileged processes are not capable of writing records to utmp,
 * wtmp and lastlog, but we do want to allow this for pseudo-terminals.
 * Because a file descriptor to a pseudo-terminal master device can only
 * be obtained by processes using the pseudo-terminal, we expect such a
 * descriptor on stdin.
 *
 * It uses the real user ID of the calling process to determine the
 * username.  It does allow users to log arbitrary hostnames.
 */

int
main(int argc, char *argv[])
{
	const char *line;

	/* Device line name. */
	if ((line = ptsname(STDIN_FILENO)) == NULL)
		return (EX_USAGE);

	if ((argc == 2 || argc == 3) && strcmp(argv[1], "login") == 0) {
		struct passwd *pwd;
		const char *host = NULL;

		/* Username. */
		pwd = getpwuid(getuid());
		if (pwd == NULL)
			return (EX_OSERR);

		/* Hostname. */
		if (argc == 3)
			host = argv[2];

		if (ulog_login(line, pwd->pw_name, host) != 0)
			return (EX_OSFILE);
		return (EX_OK);
	} else if (argc == 2 && strcmp(argv[1], "logout") == 0) {
		if (ulog_logout(line) != 0)
			return (EX_OSFILE);
		return (EX_OK);
	}

	return (EX_USAGE);
}