386BSD 0.1 development

[unix-history] / usr / src / libexec / uucp / uudir.c

/* uudir.c
  Create a directory owned by uucp.  This is Unix specific.

  Copyright (C) 1992 Ian Lance Taylor

  This file is part of the Taylor UUCP package.

  This program is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; either version 2 of the
  License, or (at your option) any later version.

  This program is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

  The author of the program may be contacted at ian@airs.com or
  c/o AIRS, P.O. Box 520, Waltham, MA 02254.

  $Log: uudir.c,v $
  Revision 1.1  1992/02/09  05:11:42  ian
  Initial revision

  */

#include "uucp.h"

#if USE_RCS_ID
char uudir_rcsid[] = "$Id: uudir.c,v 1.1 1992/02/09 05:11:42 ian Rel $";
#endif

#include <pwd.h>

#if USE_STDIO && HAVE_UNISTD_H
#include <unistd.h>
#endif

#include "sysdep.h"

/* External functions.  */
extern int setuid ();
extern struct passwd *getpwnam ();
\f
/* This is a simple program which sets its real uid to uucp and then
  invokes /bin/mkdir.  It is only used if the system does not support
  the mkdir system call.  It must be installed suid to root.

  This program is needed because the UUCP programs will be run suid
  to uucp.  On a system without the mkdir system call, /bin/mkdir is
  a suid root program.  This means that /bin/mkdir always creates
  directories using the real uid, rather than the effective uid.
  This is wrong, since the UUCP programs always want to create
  directories that are owned by uucp.  Therefore, this simple suid
  root program is used to force /bin/mkdir into making a directory
  owned by uucp.

  If we made the program publically executable, this would mean that
  anybody could create a directory owned by uucp.  This is probably
  not a good thing, but since the program must be owned by root we
  can't simply make it executable only by uucp.  Therefore, the
  Makefile hides the program away in /usr/lib/uucp/util, and makes
  that directory searchable only by uucp.  This should prevent
  anybody else from getting to the program.

  This is not a perfect solution, since any suid root program is by
  definition a potential security hole.  I really can't see any way
  to avoid this, though.  */

int
main (argc, argv)
    int argc;
    char **argv;
{
 struct passwd *q;
 const char *zprog, *zname;

 /* We don't print any error messages, since this program should
    never be run directly by a user.  */

 if (argc != 2)
   exit (EXIT_FAILURE);

 /* OWNER is passed in from the Makefile.  It will normally be
    "uucp".  */
 q = getpwnam (OWNER);
 if (q == NULL)
   exit (EXIT_FAILURE);

 if (setuid (q->pw_uid) < 0)
   exit (EXIT_FAILURE);

 zprog = MKDIR_PROGRAM;
 zname = strrchr (zprog, '/');
 if (zname == NULL)
   zname = zprog;
 else
   ++zname;

 (void) execl (zprog, zname, argv[1], (char *) NULL);
 exit (EXIT_FAILURE);
}