shadow/libmisc/chowntty.c

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/*
* Copyright 1989 - 1994, Julianne Frances Haugh
* 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.
* 4. Neither the name of Julianne F. Haugh nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JULIE HAUGH 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 JULIE HAUGH 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 int is_my_tty (const char *tty)
{
struct stat by_name, by_fd;
if (stat (tty, &by_name) || fstat (0, &by_fd))
return 0;
if (by_name.st_rdev != by_fd.st_rdev)
return 0;
else
return 1;
}
/*
* 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.
*/
if (!(group = getdef_str ("TTYGROUP")))
gid = info->pw_gid;
else if (group[0] >= '0' && group[0] <= '9')
gid = atoi (group);
else if ((grent = getgrnam (group)))
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) ||
chmod (tty, getdef_num ("TTYPERM", 0600))) {
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 (err != EROFS)
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
}