1 /* $NetBSD: privs.h,v 1.5 2002/07/10 23:16:34 wiz Exp $ */ 2 3 /* 4 * privs.h - header for privileged operations 5 * Copyright (C) 1993 Thomas Koenig 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. The name of the author(s) may not be used to endorse or promote 13 * products derived from this software without specific prior written 14 * permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 * From: OpenBSD: privs.h,v 1.4 1997/03/01 23:40:12 millert Exp 28 */ 29 30 #ifndef _PRIVS_H 31 #define _PRIVS_H 32 33 #include <unistd.h> 34 35 /* Relinquish privileges temporarily for a setuid or setgid program 36 * with the option of getting them back later. This is done by 37 * utilizing POSIX saved user and groups ids. Call RELINQUISH_PRIVS once 38 * at the beginning of the main program. This will cause all operatons 39 * to be executed with the real userid. When you need the privileges 40 * of the setuid/setgid invocation, call PRIV_START; when you no longer 41 * need it, call PRIV_END. Note that it is an error to call PRIV_START 42 * and not PRIV_END within the same function. 43 * 44 * Use RELINQUISH_PRIVS_ROOT(a,b) if your program started out running 45 * as root, and you want to drop back the effective userid to a 46 * and the effective group id to b, with the option to get them back 47 * later. 48 * 49 * Problems: Do not use return between PRIV_START and PRIV_END; this 50 * will cause the program to continue running in an unprivileged 51 * state. 52 * 53 * It is NOT safe to call exec(), system() or popen() with a user- 54 * supplied program (i.e. without carefully checking PATH and any 55 * library load paths) with relinquished privileges; the called program 56 * can acquire them just as easily. Set both effective and real userid 57 * to the real userid before calling any of them. 58 */ 59 60 #ifndef MAIN 61 extern 62 #endif 63 uid_t real_uid, effective_uid; 64 65 #ifndef MAIN 66 extern 67 #endif 68 gid_t real_gid, effective_gid; 69 70 #define RELINQUISH_PRIVS { \ 71 real_uid = getuid(); \ 72 effective_uid = geteuid(); \ 73 real_gid = getgid(); \ 74 effective_gid = getegid(); \ 75 PRIV_END \ 76 } 77 78 #define RELINQUISH_PRIVS_ROOT(a, b) { \ 79 real_uid = (a); \ 80 effective_uid = geteuid(); \ 81 real_gid = (b); \ 82 effective_gid = getegid(); \ 83 PRIV_END \ 84 } 85 86 #define PRIV_START { \ 87 if (seteuid(effective_uid) == -1) \ 88 perr("Cannot get user privs"); \ 89 if (setegid(effective_gid) == -1) \ 90 perr("Cannot get group privs"); \ 91 } 92 93 #define PRIV_END { \ 94 if (setegid(real_gid) == -1) \ 95 perr("Cannot relinguish group privs"); \ 96 if (seteuid(real_uid) == -1) \ 97 perr("Cannot relinguish user privs"); \ 98 } 99 100 #endif 101