freebsd-dev/lib/libc/sys/issetugid.2

.\"	$OpenBSD: issetugid.2,v 1.7 1997/02/18 00:16:09 deraadt Exp $
.\"
.\" Copyright (c) 1980, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" 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. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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, WHETHER 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.
.\"
.Dd August 25, 1996
.Dt ISSETUGID 2
.Os
.Sh NAME
.Nm issetugid
.Nd is current process tainted by uid or gid changes
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In unistd.h
.Ft int
.Fn issetugid void
.Sh DESCRIPTION
The
.Fn issetugid
system call returns 1 if the process environment or memory address space
is considered
.Dq tainted ,
and returns 0 otherwise.
.Pp
A process is tainted if it was created as a result of an
.Xr execve 2
system call which had either of the setuid or setgid bits set (and extra
privileges were given as a result) or if it has changed any of its real,
effective or saved user or group ID's since it began execution.
.Pp
This system call exists so that library routines (eg: libc, libtermcap)
can reliably determine if it is safe to use information
that was obtained from the user, in particular the results from
.Xr getenv 3
should be viewed with suspicion if it is used to control operation.
.Pp
A
.Dq tainted
status is inherited by child processes as a result of the
.Xr fork 2
system call (or other library code that calls fork, such as
.Xr popen 3 ) .
.Pp
It is assumed that a program that clears all privileges as it prepares
to execute another will also reset the environment, hence the
.Dq tainted
status will not be passed on.
This is important for programs such as
.Xr su 1
which begin setuid but need to be able to create an untainted process.
.Sh ERRORS
The
.Fn issetugid
system call is always successful, and no return value is reserved to
indicate an error.
.Sh SEE ALSO
.Xr execve 2 ,
.Xr fork 2 ,
.Xr setegid 2 ,
.Xr seteuid 2 ,
.Xr setgid 2 ,
.Xr setregid 2 ,
.Xr setreuid 2 ,
.Xr setuid 2
.Sh HISTORY
The
.Fn issetugid
system call first appeared in
.Ox 2.0
and was also implemented in
.Fx 3.0 .
Steal issetugid man page from OpenBSD. Needs work.. Obtained from: OpenBSD 1997-03-31 15:59:14 +00:00			`.\" $OpenBSD: issetugid.2,v 1.7 1997/02/18 00:16:09 deraadt Exp $`
			`.\"`
			`.\" Copyright (c) 1980, 1991, 1993`
			`.\" The Regents of the University of California. All rights reserved.`
			`.\"`
			`.\" 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. Redistributions in binary form must reproduce the above copyright`
			`.\" notice, this list of conditions and the following disclaimer in the`
			`.\" documentation and/or other materials provided with the distribution.`
Renumber copyright clause 4 Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96 2017-02-28 23:42:47 +00:00			`.\" 3. Neither the name of the University nor the names of its contributors`
Steal issetugid man page from OpenBSD. Needs work.. Obtained from: OpenBSD 1997-03-31 15:59:14 +00:00			`.\" may be used to endorse or promote products derived from this software`
			`.\" without specific prior written permission.`
			`.\"`
			.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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, WHETHER 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.`
			`.\"`
mdoc(7) police: use canonical form of .Dd macro. 2000-12-11 15:15:20 +00:00			`.Dd August 25, 1996`
Steal issetugid man page from OpenBSD. Needs work.. Obtained from: OpenBSD 1997-03-31 15:59:14 +00:00			`.Dt ISSETUGID 2`
General cleanup and update to specify exactly how our implementation passes on the status across fork/exec. The previous version had some typos, referred to itself as link(2) in one place :-), and didn't really match openbsd's implementation either. Now that I've mentioned typos, hopefully our Typo Police and Xref Police will be gentle with me. :-) 1997-03-31 16:36:14 +00:00			`.Os`
Steal issetugid man page from OpenBSD. Needs work.. Obtained from: OpenBSD 1997-03-31 15:59:14 +00:00			`.Sh NAME`
			`.Nm issetugid`
General cleanup and update to specify exactly how our implementation passes on the status across fork/exec. The previous version had some typos, referred to itself as link(2) in one place :-), and didn't really match openbsd's implementation either. Now that I've mentioned typos, hopefully our Typo Police and Xref Police will be gentle with me. :-) 1997-03-31 16:36:14 +00:00			`.Nd is current process tainted by uid or gid changes`
Introduce ".Lb" macro to libc manpages. More libraries manpages updates following. 2000-04-21 09:42:15 +00:00			`.Sh LIBRARY`
			`.Lb libc`
Steal issetugid man page from OpenBSD. Needs work.. Obtained from: OpenBSD 1997-03-31 15:59:14 +00:00			`.Sh SYNOPSIS`
mdoc(7) police: Use the new .In macro for #include statements. 2001-10-01 16:09:29 +00:00			`.In unistd.h`
Steal issetugid man page from OpenBSD. Needs work.. Obtained from: OpenBSD 1997-03-31 15:59:14 +00:00			`.Ft int`
			`.Fn issetugid void`
			`.Sh DESCRIPTION`
			`The`
			`.Fn issetugid`
mdoc(7) police: Tidy up the syscall language. Stop calling system calls "function calls". Use "The .Fn system call" a-la "The .Nm utility". When referring to a non-BSD implementation in the HISTORY section, call syscall a function, to be safe. 2002-12-18 09:22:32 +00:00			`system call returns 1 if the process environment or memory address space`
Some style and "look" fixes Reviewed by: mpp 1999-09-05 07:02:22 +00:00			`is considered`
			`.Dq tainted ,`
			`and returns 0 otherwise.`
Steal issetugid man page from OpenBSD. Needs work.. Obtained from: OpenBSD 1997-03-31 15:59:14 +00:00			`.Pp`
General cleanup and update to specify exactly how our implementation passes on the status across fork/exec. The previous version had some typos, referred to itself as link(2) in one place :-), and didn't really match openbsd's implementation either. Now that I've mentioned typos, hopefully our Typo Police and Xref Police will be gentle with me. :-) 1997-03-31 16:36:14 +00:00			`A process is tainted if it was created as a result of an`
			`.Xr execve 2`
			`system call which had either of the setuid or setgid bits set (and extra`
Grammar police: "its", not "it's", is the possessive form of "it". 2001-04-15 19:53:47 +00:00			`privileges were given as a result) or if it has changed any of its real,`
General cleanup and update to specify exactly how our implementation passes on the status across fork/exec. The previous version had some typos, referred to itself as link(2) in one place :-), and didn't really match openbsd's implementation either. Now that I've mentioned typos, hopefully our Typo Police and Xref Police will be gentle with me. :-) 1997-03-31 16:36:14 +00:00			`effective or saved user or group ID's since it began execution.`
Steal issetugid man page from OpenBSD. Needs work.. Obtained from: OpenBSD 1997-03-31 15:59:14 +00:00			`.Pp`
General cleanup and update to specify exactly how our implementation passes on the status across fork/exec. The previous version had some typos, referred to itself as link(2) in one place :-), and didn't really match openbsd's implementation either. Now that I've mentioned typos, hopefully our Typo Police and Xref Police will be gentle with me. :-) 1997-03-31 16:36:14 +00:00			`This system call exists so that library routines (eg: libc, libtermcap)`
			`can reliably determine if it is safe to use information`
			`that was obtained from the user, in particular the results from`
			`.Xr getenv 3`
			`should be viewed with suspicion if it is used to control operation.`
			`.Pp`
Some style and "look" fixes Reviewed by: mpp 1999-09-05 07:02:22 +00:00			`A`
			`.Dq tainted`
			`status is inherited by child processes as a result of the`
General cleanup and update to specify exactly how our implementation passes on the status across fork/exec. The previous version had some typos, referred to itself as link(2) in one place :-), and didn't really match openbsd's implementation either. Now that I've mentioned typos, hopefully our Typo Police and Xref Police will be gentle with me. :-) 1997-03-31 16:36:14 +00:00			`.Xr fork 2`
			`system call (or other library code that calls fork, such as`
Fix one very minor mdoc problem. Gentle enough, Peter? :-) 1997-04-01 18:45:57 +00:00			`.Xr popen 3 ) .`
General cleanup and update to specify exactly how our implementation passes on the status across fork/exec. The previous version had some typos, referred to itself as link(2) in one place :-), and didn't really match openbsd's implementation either. Now that I've mentioned typos, hopefully our Typo Police and Xref Police will be gentle with me. :-) 1997-03-31 16:36:14 +00:00			`.Pp`
			`It is assumed that a program that clears all privileges as it prepares`
Some style and "look" fixes Reviewed by: mpp 1999-09-05 07:02:22 +00:00			`to execute another will also reset the environment, hence the`
			`.Dq tainted`
Mechanically kill hard sentence breaks. 2004-07-02 23:52:20 +00:00			`status will not be passed on.`
			`This is important for programs such as`
General cleanup and update to specify exactly how our implementation passes on the status across fork/exec. The previous version had some typos, referred to itself as link(2) in one place :-), and didn't really match openbsd's implementation either. Now that I've mentioned typos, hopefully our Typo Police and Xref Police will be gentle with me. :-) 1997-03-31 16:36:14 +00:00			`.Xr su 1`
			`which begin setuid but need to be able to create an untainted process.`
Steal issetugid man page from OpenBSD. Needs work.. Obtained from: OpenBSD 1997-03-31 15:59:14 +00:00			`.Sh ERRORS`
			`The`
			`.Fn issetugid`
mdoc(7) police: Tidy up the syscall language. Stop calling system calls "function calls". Use "The .Fn system call" a-la "The .Nm utility". When referring to a non-BSD implementation in the HISTORY section, call syscall a function, to be safe. 2002-12-18 09:22:32 +00:00			`system call is always successful, and no return value is reserved to`
Steal issetugid man page from OpenBSD. Needs work.. Obtained from: OpenBSD 1997-03-31 15:59:14 +00:00			`indicate an error.`
			`.Sh SEE ALSO`
			`.Xr execve 2 ,`
General cleanup and update to specify exactly how our implementation passes on the status across fork/exec. The previous version had some typos, referred to itself as link(2) in one place :-), and didn't really match openbsd's implementation either. Now that I've mentioned typos, hopefully our Typo Police and Xref Police will be gentle with me. :-) 1997-03-31 16:36:14 +00:00			`.Xr fork 2 ,`
			`.Xr setegid 2 ,`
			`.Xr seteuid 2 ,`
Sort cross refereces in section SEE ALSO. 1997-09-29 19:11:55 +00:00			`.Xr setgid 2 ,`
General cleanup and update to specify exactly how our implementation passes on the status across fork/exec. The previous version had some typos, referred to itself as link(2) in one place :-), and didn't really match openbsd's implementation either. Now that I've mentioned typos, hopefully our Typo Police and Xref Police will be gentle with me. :-) 1997-03-31 16:36:14 +00:00			`.Xr setregid 2 ,`
Don't xref setregid(2) twice - one of them should be setreuid(2). 1997-04-01 18:50:56 +00:00			`.Xr setreuid 2 ,`
General cleanup and update to specify exactly how our implementation passes on the status across fork/exec. The previous version had some typos, referred to itself as link(2) in one place :-), and didn't really match openbsd's implementation either. Now that I've mentioned typos, hopefully our Typo Police and Xref Police will be gentle with me. :-) 1997-03-31 16:36:14 +00:00			`.Xr setuid 2`
Steal issetugid man page from OpenBSD. Needs work.. Obtained from: OpenBSD 1997-03-31 15:59:14 +00:00			`.Sh HISTORY`
mdoc(7) police: Tidy up the syscall language. Stop calling system calls "function calls". Use "The .Fn system call" a-la "The .Nm utility". When referring to a non-BSD implementation in the HISTORY section, call syscall a function, to be safe. 2002-12-18 09:22:32 +00:00			`The`
General cleanup and update to specify exactly how our implementation passes on the status across fork/exec. The previous version had some typos, referred to itself as link(2) in one place :-), and didn't really match openbsd's implementation either. Now that I've mentioned typos, hopefully our Typo Police and Xref Police will be gentle with me. :-) 1997-03-31 16:36:14 +00:00			`.Fn issetugid`
mdoc(7) police: Tidy up the syscall language. Stop calling system calls "function calls". Use "The .Fn system call" a-la "The .Nm utility". When referring to a non-BSD implementation in the HISTORY section, call syscall a function, to be safe. 2002-12-18 09:22:32 +00:00			`system call first appeared in`
General cleanup and update to specify exactly how our implementation passes on the status across fork/exec. The previous version had some typos, referred to itself as link(2) in one place :-), and didn't really match openbsd's implementation either. Now that I've mentioned typos, hopefully our Typo Police and Xref Police will be gentle with me. :-) 1997-03-31 16:36:14 +00:00			`.Ox 2.0`
			`and was also implemented in`
			`.Fx 3.0 .`