freebsd-dev/usr.bin/at/privs.h
Eitan Adler 1d1d4a4727 Check the return error of set[ug]id. While this can never fail in the
current version of FreeBSD, this isn't guarenteed by the API.  Custom
security modules, or future implementations of the setuid and setgid
may fail.

PR:		bin/172289
PR:		bin/172290
PR:		bin/172291
Submittud by:	Erik Cederstrand <erik@cederstrand.dk>
Discussed by:	freebsd-security
Approved by:	cperciva
MFC after:	1 week
2012-10-22 03:31:22 +00:00

107 lines
3.9 KiB
C

/*
* 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 (setreuid((uid_t)-1, effective_uid) != 0) err(1, "setreuid failed"); \
if (setregid((gid_t)-1, effective_gid) != 0) err(1, "setregid failed"); \
PRIV_END \
}
#endif