shadow/libmisc/chowntty.c

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/*
* Copyright (c) 1989 - 1994, Julianne Frances Haugh
* Copyright (c) 1996 - 2001, Marek Michałkiewicz
* Copyright (c) 2003 - 2005, Tomasz Kłoczko
2008-05-26 05:01:10 +05:30
* Copyright (c) 2007 - 2008, Nicolas François
* 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.
* 3. The name of the copyright holders or contributors may not be used to
* endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
* HOLDERS 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 <config.h>
#ident "$Id$"
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <errno.h>
#include <grp.h>
#include "prototypes.h"
#include "defines.h"
#include <pwd.h>
#include "getdef.h"
/*
* is_my_tty -- determine if "tty" is the same as TTY stdin is using
*/
static bool is_my_tty (const char *tty)
{
struct stat by_name, by_fd;
if ((stat (tty, &by_name) != 0) || (fstat (0, &by_fd) != 0)) {
return false;
}
if (by_name.st_rdev != by_fd.st_rdev) {
return false;
} else {
return true;
}
}
/*
* chown_tty() sets the login tty to be owned by the new user ID
* with TTYPERM modes
*/
void chown_tty (const char *tty, const struct passwd *info)
{
char buf[200], full_tty[200];
char *group; /* TTY group name or number */
struct group *grent;
gid_t gid;
/*
* See if login.defs has some value configured for the port group
* ID. Otherwise, use the user's primary group ID.
*/
group = getdef_str ("TTYGROUP");
if (NULL == group) {
gid = info->pw_gid;
} else if ((group[0] >= '0') && (group[0] <= '9')) {
gid = (gid_t) atol (group);
} else {
grent = getgrnam (group); /* local, no need for xgetgrnam */
if (NULL != grent) {
gid = grent->gr_gid;
} else {
gid = info->pw_gid;
}
}
/*
* Change the permissions on the TTY to be owned by the user with
* the group as determined above.
*/
if ('/' != *tty) {
snprintf (full_tty, sizeof full_tty, "/dev/%s", tty);
tty = full_tty;
}
if (!is_my_tty (tty)) {
SYSLOG ((LOG_WARN,
"unable to determine TTY name, got %s\n", tty));
closelog ();
exit (1);
}
if ( (chown (tty, info->pw_uid, gid) != 0)
|| (chmod (tty, getdef_num ("TTYPERM", 0600)) != 0)) {
int err = errno;
snprintf (buf, sizeof buf, _("Unable to change tty %s"), tty);
perror (buf);
SYSLOG ((LOG_WARN,
"unable to change tty `%s' for user `%s'\n", tty,
info->pw_name));
closelog ();
if (EROFS != err) {
exit (1);
}
}
#ifdef __linux__
/*
* Please don't add code to chown /dev/vcs* to the user logging in -
* it's a potential security hole. I wouldn't like the previous user
* to hold the file descriptor open and watch my screen. We don't
* have the *BSD revoke() system call yet, and vhangup() only works
* for tty devices (which vcs* is not). --marekm
*/
#endif
}