1 /*********************************************************************** 2 * * 3 * This software is part of the ast package * 4 * Copyright (c) 1985-2009 AT&T Intellectual Property * 5 * and is licensed under the * 6 * Common Public License, Version 1.0 * 7 * by AT&T Intellectual Property * 8 * * 9 * A copy of the License is available at * 10 * http://www.opensource.org/licenses/cpl1.0.txt * 11 * (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) * 12 * * 13 * Information and Software Systems Research * 14 * AT&T Research * 15 * Florham Park NJ * 16 * * 17 * Glenn Fowler <gsf@research.att.com> * 18 * David Korn <dgk@research.att.com> * 19 * Phong Vo <kpv@research.att.com> * 20 * * 21 ***********************************************************************/ 22 #pragma prototyped 23 /* 24 * AT&T Bell Laboratories 25 * return 1 if dir [any dir] is the preroot 26 */ 27 28 #include <ast.h> 29 #include <preroot.h> 30 31 #if FS_PREROOT 32 33 #include <ls.h> 34 35 /* 36 * return 1 if files a and b are the same under preroot 37 * 38 * NOTE: the kernel disables preroot for set-uid processes 39 */ 40 41 static int 42 same(const char* a, const char* b) 43 { 44 int i; 45 int euid; 46 int ruid; 47 48 struct stat ast; 49 struct stat bst; 50 51 if ((ruid = getuid()) != (euid = geteuid())) setuid(ruid); 52 i = !stat(a, &ast) && !stat(b, &bst) && ast.st_dev == bst.st_dev && ast.st_ino == bst.st_ino; 53 if (ruid != euid) setuid(euid); 54 return(i); 55 } 56 57 int 58 ispreroot(const char* dir) 59 { 60 static int prerooted = -1; 61 62 if (dir) return(same("/", dir)); 63 if (prerooted < 0) prerooted = !same("/", PR_REAL); 64 return(prerooted); 65 } 66 67 #else 68 69 NoN(ispreroot) 70 71 #endif 72