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/*
* privs.h - header for privileged operations
* Copyright (C) 1993 Thomas Koenig
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. The name of the author(s) may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $FreeBSD$
*/
#ifndef _PRIVS_H
#define _PRIVS_H
#include <unistd.h>
/* Relinquish privileges temporarily for a setuid or setgid program
* with the option of getting them back later. This is done by
* utilizing POSIX saved user and group IDs. Call RELINQUISH_PRIVS once
* at the beginning of the main program. This will cause all operations
* to be executed with the real userid. When you need the privileges
* of the setuid/setgid invocation, call PRIV_START; when you no longer
* need it, call PRIV_END. Note that it is an error to call PRIV_START
* and not PRIV_END within the same function.
*
* Use RELINQUISH_PRIVS_ROOT(a,b) if your program started out running
* as root, and you want to drop back the effective userid to a
* and the effective group id to b, with the option to get them back
* later.
*
* If you no longer need root privileges, but those of some other
* userid/groupid, you can call REDUCE_PRIV(a,b) when your effective
* is the user's.
*
* Problems: Do not use return between PRIV_START and PRIV_END; this
* will cause the program to continue running in an unprivileged
* state.
*
* It is NOT safe to call exec(), system() or popen() with a user-
* supplied program (i.e. without carefully checking PATH and any
* library load paths) with relinquished privileges; the called program
* can acquire them just as easily. Set both effective and real userid
* to the real userid before calling any of them.
*/
extern uid_t real_uid, effective_uid;
extern gid_t real_gid, effective_gid;
#ifdef MAIN
uid_t real_uid, effective_uid;
gid_t real_gid, effective_gid;
#endif
#define RELINQUISH_PRIVS { \
real_uid = getuid(); \
effective_uid = geteuid(); \
real_gid = getgid(); \
effective_gid = getegid(); \
if (seteuid(real_uid) != 0) err(1, "seteuid failed"); \
if (setegid(real_gid) != 0) err(1, "setegid failed"); \
}
#define RELINQUISH_PRIVS_ROOT(a, b) { \
real_uid = (a); \
effective_uid = geteuid(); \
real_gid = (b); \
effective_gid = getegid(); \
if (setegid(real_gid) != 0) err(1, "setegid failed"); \
if (seteuid(real_uid) != 0) err(1, "seteuid failed"); \
}
#define PRIV_START { \
if (seteuid(effective_uid) != 0) err(1, "seteuid failed"); \
if (setegid(effective_gid) != 0) err(1, "setegid failed"); \
}
#define PRIV_END { \
if (setegid(real_gid) != 0) err(1, "setegid failed"); \
if (seteuid(real_uid) != 0) err(1, "seteuid failed"); \
}
#define REDUCE_PRIV(a, b) { \
PRIV_START \
effective_uid = (a); \
effective_gid = (b); \
if (setregid((gid_t)-1, effective_gid) != 0) err(1, "setregid failed"); \
if (setreuid((uid_t)-1, effective_uid) != 0) err(1, "setreuid failed"); \
PRIV_END \
}
#endif
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