xnu-4903.270.47.tar.gz

[apple/xnu.git] / bsd / man / man2 / issetugid.2

diff --git a/bsd/man/man2/issetugid.2 b/bsd/man/man2/issetugid.2
index aca73d10e160a65c199d7b85299db8d60644813b..6b202e55aaeee251e09bb2520bc539e47445ee66 100644 (file)
--- a/bsd/man/man2/issetugid.2
+++ b/bsd/man/man2/issetugid.2
@@ -31,57 +31,72 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"

-.Dd August, 25 1996
+.\" $FreeBSD: src/lib/libc/sys/issetugid.2,v 1.13 2004/07/02 23:52:13 ru Exp $
+.\"
+.Dd August 25, 1996

 .Dt ISSETUGID 2
 .Dt ISSETUGID 2

-.Os OpenBSD 2.0
+.Os

 .Sh NAME
 .Nm issetugid
 .Sh NAME
 .Nm issetugid

-.Nd is current executable running setuid or setgid
+.Nd is current process tainted by uid or gid changes
+.Sh LIBRARY
+.Lb libc

 .Sh SYNOPSIS
 .Sh SYNOPSIS

-.Fd #include <unistd.h>
+.In unistd.h

 .Ft int
 .Fn issetugid void
 .Sh DESCRIPTION
 The
 .Fn issetugid
 .Ft int
 .Fn issetugid void
 .Sh DESCRIPTION
 The
 .Fn issetugid

-function returns 1 if the process was made setuid or setgid as
-the result of the last
-.Fn execve
-system call.
-Otherwise it returns 0.
+system call returns 1 if the process environment or memory address space
+is considered
+.Dq tainted ,
+and returns 0 otherwise.

 .Pp
 .Pp

-This system call exists so that library routines (inside libc, libtermlib,
-or other libraries) can gaurantee safe behavior when used inside
-setuid or setgid programs.
-Some library routines may not be passed sufficient information to know
-if the current program was started setuid or setgid because higher level
-calling code may have made changes to the uid or the euid.
-In particular, it is wise to use this call to determine if a
-pathname returned from a
-.Fn getenv
-call may safely be used to
-.Fn open
-the specified file.
+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
 .Pp

-.Fn issetugid
-is unaffected by calls to
-.Fn setuid ,
-.Fn fork ,
-and other such calls.  It is only controlled by
-.Fn execve .
+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
 .Sh ERRORS
 The
 .Fn issetugid

-function is always successful, and no return value is reserved to
+system call is always successful, and no return value is reserved to

 indicate an error.
 .Sh SEE ALSO
 .Xr execve 2 ,
 indicate an error.
 .Sh SEE ALSO
 .Xr execve 2 ,

-.Xr setuid 2 ,
-.Xr seteuid 2,
+.Xr fork 2 ,
+.Xr setegid 2 ,
+.Xr seteuid 2 ,

 .Xr setgid 2 ,
 .Xr setgid 2 ,

-.Xr setegid 2
+.Xr setregid 2 ,
+.Xr setreuid 2 ,
+.Xr setuid 2

 .Sh HISTORY
 .Sh HISTORY

-A
-.Fn lstat
-function call appeared in
-OpenBSD 2.0
+The
+.Fn issetugid
+system call first appeared in
+.Ox 2.0
+and was also implemented in
+.Fx 3.0 .