NetBSD/share/man/man9/pfil.9

135 lines
4.3 KiB
Groff
Raw Normal View History

2000-02-20 04:03:13 +03:00
.\" $NetBSD: pfil.9,v 1.13 2000/02/20 01:03:13 darrenr Exp $
1996-09-06 09:27:47 +04:00
.\"
.\" Copyright (c) 1996 Matthew R. Green
1996-09-06 09:27:47 +04:00
.\" 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. The name of the author may not be used to endorse or promote products
.\" derived from this software without specific prior written permission.
1996-09-06 09:27:47 +04:00
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
1996-09-06 09:27:47 +04:00
.\"
.Dd August 4, 1996
.Dt PFIL 9
.Os
1996-09-06 09:27:47 +04:00
.Sh NAME
1997-11-11 13:06:37 +03:00
.Nm pfil ,
.Nm pfil_hook_get ,
.Nm pfil_add_hook ,
.Nm pfil_remove_hook
1996-09-06 09:27:47 +04:00
.Nd packet filter interface
.Sh SYNOPSIS
.Fd #include <sys/param.h>
.Fd #include <sys/mbuf.h>
.Fd #include <net/if.h>
.Fd #include <net/pfil.h>
1996-09-06 09:27:47 +04:00
.Ft struct packet_filter_hook *
2000-02-20 04:03:13 +03:00
.Fn pfil_hook_get "int" "struct pfil_head *"
1996-09-06 09:27:47 +04:00
.Ft void
2000-02-20 04:03:13 +03:00
.Fn pfil_add_hook "int (*func)()" "int flags" "struct pfil_head *"
1996-09-06 09:27:47 +04:00
.Ft void
2000-02-20 04:03:13 +03:00
.Fn pfil_remove_hook "int (*func)()" "int flags" "struct pfil_head *"
1996-09-06 09:27:47 +04:00
.\"(void *, int, struct ifnet *, int, struct mbuf **)
.Sh DESCRIPTION
The
1997-04-13 17:48:51 +04:00
.Nm
interface allows a function to be called on every incoming or outgoing
packets. The hooks for these are embedded in the
.Fn ip_input
and
.Fn ip_output
1996-09-06 09:27:47 +04:00
routines. The
.Fn pfil_hook_get
1997-04-13 17:48:51 +04:00
function returns the first member of a particular hook, either the in or out
list. The
1996-09-06 09:27:47 +04:00
.Fn pfil_add_hook
function takes a function of the form below as it's first argument, and the
flags for which lists to add the function to. The possible values for these
1997-04-13 17:48:51 +04:00
flags are some combination of PFIL_IN and PFIL_OUT. The
1996-09-06 09:27:47 +04:00
.Fn pfil_remove_hook
removes a hook from the specified lists.
.Pp
The
.Va func
argument is a function with the following prototype.
.Pp
.Fn func "void *data" "int hlen" "struct ifnet *net" "int dir" "struct mbuf **m"
.Pp
The
.Va data
describes the packet. Currently, this may only be a pointer to a ip structure. The
.Va net
and
.Va m
arguments describe the network interface and the mbuf holding data for this
packet. The
.Va dir
1997-04-13 17:48:51 +04:00
is the direction; 0 for incoming packets and 1 for outgoing packets. if the function
returns non-zero, this signals an error and no further processing of this packet is
performed. The function should set errno to indicate the nature of the error.
It is the hook's responsibiliy to free the chain if the packet is being dropped.
1996-09-06 09:27:47 +04:00
.Pp
The
1997-04-13 17:48:51 +04:00
.Nm
1996-09-06 09:27:47 +04:00
interface is enabled in the kernel via the
.Sy PFIL_HOOKS
1996-09-06 09:27:47 +04:00
option.
.Sh RETURN VALUES
If successful
.Fn pfil_hook_get
returns the first member of the packet filter list,
.Fn pfil_add_hook
and
.Fn pfil_remove_hook
are expected to always succeed.
.Sh HISTORY
1997-04-13 17:48:51 +04:00
The
.Nm
interface first appeared in
1998-11-10 19:22:46 +03:00
.Nx 1.3 .
The
.Nm
input and output lists were originally implemented as
.Fd <sys/queue.h>
.Dv LIST
structures;
however this was changed in
.Nx 1.4
to
.Dv TAILQ
structures. This change was to allow the input and output filters to be
processed in reverse order, to allow the same path to be taken, in or out
of the kernel.
2000-02-20 04:03:13 +03:00
.Pp
The
.Nm
interface was changed in 1.4T to accept a 3rd parameter to both
.Fn pfil_add_hook
and
.Fn pfil_remove_hook
, introducing the capability of per-protocol filtering. This was done
primarily in order to support filtering of IPv6.
1997-04-13 17:48:51 +04:00
.Sh BUGS
The current
.Nm
implementation will need changes to suit a threaded kernel model.
1996-09-06 09:27:47 +04:00
.Sh SEE ALSO
.Xr bpf 4