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Annotation of src/usr.bin/at/privs.h, Revision 1.1

1.1     ! deraadt     1: /*     $NetBSD: privs.h,v 1.3 1995/03/25 18:13:41 glass Exp $  */
        !             2:
        !             3: /*
        !             4:  * privs.h - header for privileged operations
        !             5:  * Copyright (c) 1993 by Thomas Koenig
        !             6:  * All rights reserved.
        !             7:  *
        !             8:  * Redistribution and use in source and binary forms, with or without
        !             9:  * modification, are permitted provided that the following conditions
        !            10:  * are met:
        !            11:  * 1. Redistributions of source code must retain the above copyright
        !            12:  *    notice, this list of conditions and the following disclaimer.
        !            13:  * 2. The name of the author(s) may not be used to endorse or promote
        !            14:  *    products derived from this software without specific prior written
        !            15:  *    permission.
        !            16:  *
        !            17:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
        !            18:  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
        !            19:  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
        !            20:  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
        !            21:  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
        !            22:  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
        !            23:  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
        !            24:  * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
        !            25:  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
        !            26:  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
        !            27:  *
        !            28:  */
        !            29:
        !            30: #ifndef _PRIVS_H
        !            31: #define _PRIVS_H
        !            32:
        !            33: #include <unistd.h>
        !            34:
        !            35: /* Relinquish privileges temporarily for a setuid program
        !            36:  * with the option of getting them back later.  This is done by swapping
        !            37:  * the real and effective userid BSD style.  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 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) 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:  * If you no longer need root privileges, but those of some other
        !            50:  * userid, you can call REDUCE_PRIV(a) when your effective
        !            51:  * is the user's.
        !            52:  *
        !            53:  * Problems: Do not use return between PRIV_START and PRIV_END; this
        !            54:  * will cause the program to continue running in an unprivileged
        !            55:  * state.
        !            56:  *
        !            57:  * It is NOT safe to call exec(), system() or popen() with a user-
        !            58:  * supplied program (i.e. without carefully checking PATH and any
        !            59:  * library load paths) with relinquished privileges; the called program
        !            60:  * can aquire them just as easily.  Set both effective and real userid
        !            61:  * to the real userid before calling any of them.
        !            62:  */
        !            63:
        !            64: #ifndef MAIN
        !            65: extern
        !            66: #endif
        !            67: uid_t real_uid, effective_uid;
        !            68:
        !            69: #define RELINQUISH_PRIVS { \
        !            70:        real_uid = getuid(); \
        !            71:        effective_uid = geteuid(); \
        !            72:        seteuid(real_uid); \
        !            73: }
        !            74:
        !            75: #define RELINQUISH_PRIVS_ROOT(a) { \
        !            76:        real_uid = (a); \
        !            77:        effective_uid = geteuid(); \
        !            78:        seteuid(real_uid); \
        !            79: }
        !            80:
        !            81: #define PRIV_START { \
        !            82:        seteuid(effective_uid);
        !            83:
        !            84: #define PRIV_END \
        !            85:        seteuid(real_uid); \
        !            86: }
        !            87:
        !            88: #define REDUCE_PRIV(a) { \
        !            89:        seteuid(effective_uid); \
        !            90:        real_uid = effective_uid = (a); \
        !            91:        setuid(real_uid); \
        !            92: }
        !            93: #endif