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att
GitHub Repository: att/ast
 Path: blob/master/src/lib/libast/preroot/ispreroot.c
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/***********************************************************************

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*                                                                      *

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*               This software is part of the ast package               *

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*          Copyright (c) 1985-2011 AT&T Intellectual Property          *

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*                      and is licensed under the                       *

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*                 Eclipse Public License, Version 1.0                  *

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*                    by AT&T Intellectual Property                     *

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*                                                                      *

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*                A copy of the License is available at                 *

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*          http://www.eclipse.org/org/documents/epl-v10.html           *

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*         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *

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*                                                                      *

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*              Information and Software Systems Research               *

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*                            AT&T Research                             *

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*                           Florham Park NJ                            *

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*                                                                      *

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*                 Glenn Fowler <[email protected]>                  *

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*                  David Korn <[email protected]>                   *

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*                   Phong Vo <[email protected]>                    *

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*                                                                      *

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***********************************************************************/

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#pragma prototyped

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/*

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 * AT&T Bell Laboratories

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 * return 1 if dir [any dir] is the preroot

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 */

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#include <ast.h>

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#include <preroot.h>

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#if FS_PREROOT

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#include <ls.h>

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/*

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 * return 1 if files a and b are the same under preroot

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 *

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 * NOTE: the kernel disables preroot for set-uid processes

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 */

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static int

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same(const char* a, const char* b)

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{

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	int		i;

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	int		euid;

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	int		ruid;

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	struct stat	ast;

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	struct stat	bst;

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	if ((ruid = getuid()) != (euid = geteuid())) setuid(ruid);

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	i = !stat(a, &ast) && !stat(b, &bst) && ast.st_dev == bst.st_dev && ast.st_ino == bst.st_ino;

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	if (ruid != euid) setuid(euid);

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	return(i);

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}

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int

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ispreroot(const char* dir)

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{

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	static int	prerooted = -1;

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	if (dir) return(same("/", dir));

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	if (prerooted < 0) prerooted = !same("/", PR_REAL);

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	return(prerooted);

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}

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#else

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NoN(ispreroot)

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#endif

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