NAME    [Toc]    [Back]

       setfsgid - set group identity used for file system checks

SYNOPSIS    [Toc]    [Back]

       #include <unistd.h> /* glibc uses <sys/fsuid.h> */

       int setfsgid(uid_t fsgid);

DESCRIPTION    [Toc]    [Back]

       setfsgid  sets the group ID that the Linux kernel uses to check for all
       accesses to the file system. Normally, the value of fsgid  will	shadow
       the  value  of  the effective group ID. In fact, whenever the effective
       group ID is changed, fsgid will also be changed to new value of	effective
 group ID.

       An  explicit  call to setfsgid is usually only used by programs such as
       the Linux NFS server that need to change what group ID is used for file
       access  without	a corresponding change in the real and effective group
       IDs. A change in the normal group IDs for a program  such  as  the  NFS
       server  is  a security hole that can expose it to unwanted signals from
       other group IDs.

       setfsgid will only succeed if the caller is the superuser or  if  fsgid
       matches	either the real group ID, effective group ID, saved set-groupID,
 or the current value of fsgid.

RETURN VALUE    [Toc]    [Back]

       On success, the previous value of fsgid is  returned.   On  error,  the
       current value of fsgid is returned.

CONFORMING TO    [Toc]    [Back]

       setfsgid  is Linux specific and should not be used in programs intended
       to be portable.

BUGS    [Toc]    [Back]

       No error messages of any kind are returned to the caller. At  the  very
       least, EPERM should be returned when the call fails.

NOTE    [Toc]    [Back]

       When  glibc  determines	that  the argument is not a valid gid, it will
       return -1 and set errno to EINVAL without attempting the system call.

SEE ALSO    [Toc]    [Back]

       setfsuid(2)



Linux 1.3.15			  1995-08-06			   SETFSGID(2)