SETFSGID (2)
set group identity used for file system checks
SYNOPSIS
int setfsgid(uid_t fsgid )
DESCRIPTION
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-group-ID, or the current value of
fsgid .
RETURN VALUE
On success, the previous value of
fsgid
is returned. On error, the current value of
fsgid
is returned.
CONFORMING TO
setfsgid
is Linux specific and should not be used in programs intended to be portable.
BUGS
No error messages of any kind are returned to the caller. At the very
least,
EPERM
should be returned when the call fails.
SEE ALSO
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