1.\" Copyright (c) 1996 Matthew R. Green
2.\" All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\" notice, this list of conditions and the following disclaimer.
9.\" 2. Redistributions in binary form must reproduce the above copyright
10.\" notice, this list of conditions and the following disclaimer in the
11.\" documentation and/or other materials provided with the distribution.
12.\" 3. The name of the author may not be used to endorse or promote products
13.\" derived from this software without specific prior written permission.
14.\"
15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
20.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
21.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
22.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
23.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25.\" SUCH DAMAGE.
26.\"
| 1.\" Copyright (c) 1996 Matthew R. Green
2.\" All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\" notice, this list of conditions and the following disclaimer.
9.\" 2. Redistributions in binary form must reproduce the above copyright
10.\" notice, this list of conditions and the following disclaimer in the
11.\" documentation and/or other materials provided with the distribution.
12.\" 3. The name of the author may not be used to endorse or promote products
13.\" derived from this software without specific prior written permission.
14.\"
15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
20.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
21.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
22.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
23.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25.\" SUCH DAMAGE.
26.\"
|
27.\" $FreeBSD: head/share/man/man9/pfil.9 71895 2001-02-01 16:38:02Z ru $
| 27.\" $FreeBSD: head/share/man/man9/pfil.9 75531 2001-04-15 19:53:47Z dd $
|
28.Dd August 4, 1996
29.Dt PFIL 9
30.Os
31.Sh NAME
32.Nm pfil ,
33.Nm pfil_hook_get ,
34.Nm pfil_add_hook ,
35.Nm pfil_remove_hook
36.Nd packet filter interface
37.Sh SYNOPSIS
38.Fd #include <sys/param.h>
39.Fd #include <sys/mbuf.h>
40.Fd #include <net/if.h>
41.Fd #include <net/pfil.h>
42.Ft struct packet_filter_hook *
43.Fn pfil_hook_get "int" "struct pfil_head *"
44.Ft void
45.Fn pfil_add_hook "int (*func)()" "int flags" "struct pfil_head *"
46.Ft void
47.Fn pfil_remove_hook "int (*func)()" "int flags" "struct pfil_head *"
48.\"(void *, int, struct ifnet *, int, struct mbuf **)
49.Sh DESCRIPTION
50The
51.Nm
52interface allows a function to be called on every incoming or outgoing
53packets. The hooks for these are embedded in the
54.Fn ip_input
55and
56.Fn ip_output
57routines. The
58.Fn pfil_hook_get
59function returns the first member of a particular hook, either the in or out
60list. The
61.Fn pfil_add_hook
| 28.Dd August 4, 1996
29.Dt PFIL 9
30.Os
31.Sh NAME
32.Nm pfil ,
33.Nm pfil_hook_get ,
34.Nm pfil_add_hook ,
35.Nm pfil_remove_hook
36.Nd packet filter interface
37.Sh SYNOPSIS
38.Fd #include <sys/param.h>
39.Fd #include <sys/mbuf.h>
40.Fd #include <net/if.h>
41.Fd #include <net/pfil.h>
42.Ft struct packet_filter_hook *
43.Fn pfil_hook_get "int" "struct pfil_head *"
44.Ft void
45.Fn pfil_add_hook "int (*func)()" "int flags" "struct pfil_head *"
46.Ft void
47.Fn pfil_remove_hook "int (*func)()" "int flags" "struct pfil_head *"
48.\"(void *, int, struct ifnet *, int, struct mbuf **)
49.Sh DESCRIPTION
50The
51.Nm
52interface allows a function to be called on every incoming or outgoing
53packets. The hooks for these are embedded in the
54.Fn ip_input
55and
56.Fn ip_output
57routines. The
58.Fn pfil_hook_get
59function returns the first member of a particular hook, either the in or out
60list. The
61.Fn pfil_add_hook
|
62function takes a function of the form below as it's first argument, and the
| 62function takes a function of the form below as its first argument, and the
|
63flags for which lists to add the function to. The possible values for these
64flags are some combination of PFIL_IN and PFIL_OUT. The
65.Fn pfil_remove_hook
66removes a hook from the specified lists.
67.Pp
68The
69.Va func
70argument is a function with the following prototype.
71.Pp
72.Fn func "void *data" "int hlen" "struct ifnet *net" "int dir" "struct mbuf **m"
73.Pp
74The
75.Va data
76describes the packet. Currently, this may only be a pointer to a ip structure. The
77.Va net
78and
79.Va m
80arguments describe the network interface and the mbuf holding data for this
81packet. The
82.Va dir
83is the direction; 0 for incoming packets and 1 for outgoing packets. if the function
84returns non-zero, this signals an error and no further processing of this packet is
85performed. The function should set errno to indicate the nature of the error.
86It is the hook's responsibiliy to free the chain if the packet is being dropped.
87.Pp
88The
89.Nm
90interface is enabled in the kernel via the
91.Sy PFIL_HOOKS
92option.
93.Sh RETURN VALUES
94If successful
95.Fn pfil_hook_get
96returns the first member of the packet filter list,
97.Fn pfil_add_hook
98and
99.Fn pfil_remove_hook
100are expected to always succeed.
101.Sh HISTORY
102The
103.Nm
104interface first appeared in
105.Nx 1.3 .
106The
107.Nm
108input and output lists were originally implemented as
109.Aq Pa sys/queue.h
110.Dv LIST
111structures;
112however this was changed in
113.Nx 1.4
114to
115.Dv TAILQ
116structures. This change was to allow the input and output filters to be
117processed in reverse order, to allow the same path to be taken, in or out
118of the kernel.
119.Pp
120The
121.Nm
122interface was changed in 1.4T to accept a 3rd parameter to both
123.Fn pfil_add_hook
124and
125.Fn pfil_remove_hook ,
126introducing the capability of per-protocol filtering. This was done
127primarily in order to support filtering of IPv6.
128.Sh BUGS
129The current
130.Nm
131implementation will need changes to suit a threaded kernel model.
132.Sh SEE ALSO
133.Xr bpf 4
| 63flags for which lists to add the function to. The possible values for these
64flags are some combination of PFIL_IN and PFIL_OUT. The
65.Fn pfil_remove_hook
66removes a hook from the specified lists.
67.Pp
68The
69.Va func
70argument is a function with the following prototype.
71.Pp
72.Fn func "void *data" "int hlen" "struct ifnet *net" "int dir" "struct mbuf **m"
73.Pp
74The
75.Va data
76describes the packet. Currently, this may only be a pointer to a ip structure. The
77.Va net
78and
79.Va m
80arguments describe the network interface and the mbuf holding data for this
81packet. The
82.Va dir
83is the direction; 0 for incoming packets and 1 for outgoing packets. if the function
84returns non-zero, this signals an error and no further processing of this packet is
85performed. The function should set errno to indicate the nature of the error.
86It is the hook's responsibiliy to free the chain if the packet is being dropped.
87.Pp
88The
89.Nm
90interface is enabled in the kernel via the
91.Sy PFIL_HOOKS
92option.
93.Sh RETURN VALUES
94If successful
95.Fn pfil_hook_get
96returns the first member of the packet filter list,
97.Fn pfil_add_hook
98and
99.Fn pfil_remove_hook
100are expected to always succeed.
101.Sh HISTORY
102The
103.Nm
104interface first appeared in
105.Nx 1.3 .
106The
107.Nm
108input and output lists were originally implemented as
109.Aq Pa sys/queue.h
110.Dv LIST
111structures;
112however this was changed in
113.Nx 1.4
114to
115.Dv TAILQ
116structures. This change was to allow the input and output filters to be
117processed in reverse order, to allow the same path to be taken, in or out
118of the kernel.
119.Pp
120The
121.Nm
122interface was changed in 1.4T to accept a 3rd parameter to both
123.Fn pfil_add_hook
124and
125.Fn pfil_remove_hook ,
126introducing the capability of per-protocol filtering. This was done
127primarily in order to support filtering of IPv6.
128.Sh BUGS
129The current
130.Nm
131implementation will need changes to suit a threaded kernel model.
132.Sh SEE ALSO
133.Xr bpf 4
|