a324a7f13f
utmp.c to chowntty.c. checkutmp() now only uses an existing utmp entry if the pid matches and ut_line matches with the current tty. This fixes a possible DOS when entries can be forged in the utmp file. * libmisc/chowntty.c, src/login.c, lib/prototypes.h: Remove the tty argument from chown_tty. chown_tty always changes stdin and does not need this argument anymore.
108 lines
3.4 KiB
C
108 lines
3.4 KiB
C
/*
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* Copyright (c) 1989 - 1994, Julianne Frances Haugh
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* Copyright (c) 1996 - 2001, Marek Michałkiewicz
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* Copyright (c) 2003 - 2005, Tomasz Kłoczko
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* Copyright (c) 2007 - 2008, Nicolas François
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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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* 3. The name of the copyright holders or contributors may not be used to
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* endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <config.h>
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#ident "$Id$"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <stdio.h>
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#include <errno.h>
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#include <grp.h>
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#include "prototypes.h"
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#include "defines.h"
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#include <pwd.h>
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#include "getdef.h"
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/*
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* chown_tty() sets the login tty to be owned by the new user ID
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* with TTYPERM modes
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*/
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void chown_tty (const struct passwd *info)
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{
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char *group; /* TTY group name or number */
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struct group *grent;
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gid_t gid;
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/*
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* See if login.defs has some value configured for the port group
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* ID. Otherwise, use the user's primary group ID.
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*/
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group = getdef_str ("TTYGROUP");
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if (NULL == group) {
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gid = info->pw_gid;
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} else if ((group[0] >= '0') && (group[0] <= '9')) {
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gid = (gid_t) atol (group);
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} else {
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grent = getgrnam (group); /* local, no need for xgetgrnam */
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if (NULL != grent) {
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gid = grent->gr_gid;
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} else {
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gid = info->pw_gid;
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}
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}
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/*
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* Change the permissions on the TTY to be owned by the user with
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* the group as determined above.
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*/
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if ( (fchown (STDIN_FILENO, info->pw_uid, gid) != 0)
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|| (fchmod (STDIN_FILENO, getdef_num ("TTYPERM", 0600)) != 0)) {
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int err = errno;
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snprintf (buf, sizeof buf, _("Unable to change tty stdin"));
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perror (buf);
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SYSLOG ((LOG_WARN,
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"unable to change tty stdin for user `%s'\n",
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info->pw_name));
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closelog ();
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if (EROFS != err) {
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exit (1);
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}
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}
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#ifdef __linux__
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/*
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* Please don't add code to chown /dev/vcs* to the user logging in -
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* it's a potential security hole. I wouldn't like the previous user
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* to hold the file descriptor open and watch my screen. We don't
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* have the *BSD revoke() system call yet, and vhangup() only works
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* for tty devices (which vcs* is not). --marekm
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*/
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#endif
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}
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