1da2e3ebdSchin /***********************************************************************
2da2e3ebdSchin *                                                                      *
3da2e3ebdSchin *               This software is part of the ast package               *
4*b30d1939SAndy Fiddaman *          Copyright (c) 1985-2011 AT&T Intellectual Property          *
5da2e3ebdSchin *                      and is licensed under the                       *
6*b30d1939SAndy Fiddaman *                 Eclipse Public License, Version 1.0                  *
77c2fbfb3SApril Chin *                    by AT&T Intellectual Property                     *
8da2e3ebdSchin *                                                                      *
9da2e3ebdSchin *                A copy of the License is available at                 *
10*b30d1939SAndy Fiddaman *          http://www.eclipse.org/org/documents/epl-v10.html           *
11*b30d1939SAndy Fiddaman *         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *
12da2e3ebdSchin *                                                                      *
13da2e3ebdSchin *              Information and Software Systems Research               *
14da2e3ebdSchin *                            AT&T Research                             *
15da2e3ebdSchin *                           Florham Park NJ                            *
16da2e3ebdSchin *                                                                      *
17da2e3ebdSchin *                 Glenn Fowler <gsf@research.att.com>                  *
18da2e3ebdSchin *                  David Korn <dgk@research.att.com>                   *
19da2e3ebdSchin *                   Phong Vo <kpv@research.att.com>                    *
20da2e3ebdSchin *                                                                      *
21da2e3ebdSchin ***********************************************************************/
22da2e3ebdSchin #pragma prototyped
23da2e3ebdSchin /*
24da2e3ebdSchin  * AT&T Bell Laboratories
25da2e3ebdSchin  * return 1 if dir [any dir] is the preroot
26da2e3ebdSchin  */
27da2e3ebdSchin 
28da2e3ebdSchin #include <ast.h>
29da2e3ebdSchin #include <preroot.h>
30da2e3ebdSchin 
31da2e3ebdSchin #if FS_PREROOT
32da2e3ebdSchin 
33da2e3ebdSchin #include <ls.h>
34da2e3ebdSchin 
35da2e3ebdSchin /*
36da2e3ebdSchin  * return 1 if files a and b are the same under preroot
37da2e3ebdSchin  *
38da2e3ebdSchin  * NOTE: the kernel disables preroot for set-uid processes
39da2e3ebdSchin  */
40da2e3ebdSchin 
41da2e3ebdSchin static int
same(const char * a,const char * b)42da2e3ebdSchin same(const char* a, const char* b)
43da2e3ebdSchin {
44da2e3ebdSchin 	int		i;
45da2e3ebdSchin 	int		euid;
46da2e3ebdSchin 	int		ruid;
47da2e3ebdSchin 
48da2e3ebdSchin 	struct stat	ast;
49da2e3ebdSchin 	struct stat	bst;
50da2e3ebdSchin 
51da2e3ebdSchin 	if ((ruid = getuid()) != (euid = geteuid())) setuid(ruid);
52da2e3ebdSchin 	i = !stat(a, &ast) && !stat(b, &bst) && ast.st_dev == bst.st_dev && ast.st_ino == bst.st_ino;
53da2e3ebdSchin 	if (ruid != euid) setuid(euid);
54da2e3ebdSchin 	return(i);
55da2e3ebdSchin }
56da2e3ebdSchin 
57da2e3ebdSchin int
ispreroot(const char * dir)58da2e3ebdSchin ispreroot(const char* dir)
59da2e3ebdSchin {
60da2e3ebdSchin 	static int	prerooted = -1;
61da2e3ebdSchin 
62da2e3ebdSchin 	if (dir) return(same("/", dir));
63da2e3ebdSchin 	if (prerooted < 0) prerooted = !same("/", PR_REAL);
64da2e3ebdSchin 	return(prerooted);
65da2e3ebdSchin }
66da2e3ebdSchin 
67da2e3ebdSchin #else
68da2e3ebdSchin 
69da2e3ebdSchin NoN(ispreroot)
70da2e3ebdSchin 
71da2e3ebdSchin #endif
72