Home | History | Annotate | Line # | Download | only in at
privs.h revision 1.5 
      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