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98 lines
3.1 KiB
C
98 lines
3.1 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (c) 2009 Ed Schouten <ed@FreeBSD.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#include <pwd.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sysexits.h>
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#include <ulog.h>
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/*
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* This setuid helper utility writes user login records to disk.
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* Unprivileged processes are not capable of writing records to utmpx,
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* but we do want to allow this for pseudo-terminals. Because a file
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* descriptor to a pseudo-terminal master device can only be obtained by
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* processes using the pseudo-terminal, we expect such a descriptor on
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* stdin.
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*
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* It uses the real user ID of the calling process to determine the
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* username. It does allow users to log arbitrary hostnames.
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*/
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static const char *
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get_username(void)
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{
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const struct passwd *pw;
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const char *login;
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uid_t uid;
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/*
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* Attempt to determine the username corresponding to this login
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* session. First, validate the results of getlogin() against
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* the password database. If getlogin() returns invalid data,
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* return an arbitrary username corresponding to this uid.
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*/
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uid = getuid();
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if ((login = getlogin()) != NULL && (pw = getpwnam(login)) != NULL &&
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pw->pw_uid == uid)
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return (login);
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if ((pw = getpwuid(uid)) != NULL)
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return (pw->pw_name);
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return (NULL);
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}
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int
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main(int argc, char *argv[])
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{
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const char *line, *user, *host;
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/* Device line name. */
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if ((line = ptsname(STDIN_FILENO)) == NULL)
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return (EX_USAGE);
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if ((argc == 2 || argc == 3) && strcmp(argv[1], "login") == 0) {
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/* Username. */
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user = get_username();
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if (user == NULL)
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return (EX_OSERR);
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/* Hostname. */
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host = argc == 3 ? argv[2] : NULL;
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ulog_login(line, user, host);
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return (EX_OK);
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} else if (argc == 2 && strcmp(argv[1], "logout") == 0) {
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ulog_logout(line);
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return (EX_OK);
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}
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return (EX_USAGE);
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}
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