1.\" $NetBSD: issetugid.2,v 1.4 2002/02/08 01:28:18 ross Exp $ 2.\" OpenBSD: issetugid.2,v 1.7 1997/02/18 00:16:09 deraadt Exp 3.\" FreeBSD: src/lib/libc/sys/issetugid.2,v 1.5.2.2 1999/09/18 16:18:59 phantom Exp 4.\" 5.\" Copyright (c) 1980, 1991, 1993 6.\" The Regents of the University of California. 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. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.\" FreeBSD: src/lib/libc/sys/issetugid.2,v 1.5.2.2 1999/09/18 16:18:59 phantom Exp 37.\" 38.Dd April 22, 2000 39.Dt ISSETUGID 2 40.Os 41.Sh NAME 42.Nm issetugid 43.Nd is current process tainted by uid or gid changes 44.Sh SYNOPSIS 45.Fd #include \*[Lt]unistd.h\*[Gt] 46.Ft int 47.Fn issetugid void 48.Sh DESCRIPTION 49The 50.Fn issetugid 51function returns 1 if the process environment or memory address space 52is considered 53.Dq tainted , 54and returns 0 otherwise. 55.Pp 56A process is tainted if it was created as a result of an 57.Xr execve 2 58system call which had either of the setuid or setgid bits set (and extra 59privileges were given as a result) or if it has changed any of it's real, 60effective or saved user or group ID's since it began execution. 61.Pp 62This system call exists so that library routines (eg: libc, libtermcap) 63can reliably determine if it is safe to use information 64that was obtained from the user, in particular the results from 65.Xr getenv 3 66should be viewed with suspicion if it is used to control operation. 67.Pp 68A 69.Dq tainted 70status is inherited by child processes as a result of the 71.Xr fork 2 72system call (or other library code that calls fork, such as 73.Xr popen 3 ) . 74.Pp 75It is assumed that a program that clears all privileges as it prepares 76to execute another will also reset the environment, hence the 77.Dq tainted 78status will not be passed on. This is important for programs such as 79.Xr su 1 80which begin setuid but need to be able to create an untainted process. 81.Sh ERRORS 82The 83.Fn issetugid 84function is always successful, and no return value is reserved to 85indicate an error. 86.Sh SEE ALSO 87.Xr execve 2 , 88.Xr fork 2 , 89.Xr setegid 2 , 90.Xr seteuid 2 , 91.Xr setgid 2 , 92.Xr setregid 2 , 93.Xr setreuid 2 , 94.Xr setuid 2 95.Sh HISTORY 96A 97.Fn issetugid 98function call first appeared in 99.Bx Open 1002.0 and was also implemented in 101.Fx 3.0 . 102.Fx 103implementation was imported in 104.Nx 1.5 . 105