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/* $NetBSD: privs.c,v 1.3 2018/02/25 23:48:16 htodd Exp $ */
/*
* privs.c - 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.
*
* From: OpenBSD: privs.h,v 1.4 1997/03/01 23:40:12 millert Exp
*/
#include <unistd.h>
#include "privs.h"
/*
* Used by: usr.bin/at
* Used by: libexec/atrun
*/
/*
* Relinquish privileges temporarily for a setuid or setgid program
* with the option of getting them back later. This is done by
* using POSIX saved user and groups 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.
*
* 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.
*/
uid_t real_uid, effective_uid;
gid_t real_gid, effective_gid;
void
privs_enter(void)
{
if (seteuid(effective_uid) == -1)
privs_fail("Cannot get user privs");
if (setegid(effective_gid) == -1)
privs_fail("Cannot get group privs");
}
void
privs_exit(void)
{
if (setegid(real_gid) == -1)
privs_fail("Cannot relinquish group privs");
if (seteuid(real_uid) == -1)
privs_fail("Cannot relinquish user privs");
}
void
privs_relinquish(void)
{
real_uid = getuid();
effective_uid = geteuid();
real_gid = getgid();
effective_gid = getegid();
privs_exit();
}
void
privs_relinquish_root(uid_t ruid, gid_t rgid)
{
real_uid = ruid;
real_gid = rgid;
effective_uid = geteuid();
effective_gid = getegid();
privs_exit();
}
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