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New pfil(9) KPI together with newborn pfil API and control utility.

The KPI have been reviewed and cleansed of features that were planned
back 20 years ago and never implemented.  The pfil(9) internals have
been made opaque to protocols with only returned types and function
declarations exposed. The KPI is made more strict, but at the same time
more extensible, as kernel uses same command structures that userland
ioctl uses.

In nutshell [KA]PI is about declaring filtering points, declaring
filters and linking and unlinking them together.

New [KA]PI makes it possible to reconfigure pfil(9) configuration:
change order of hooks, rehook filter from one filtering point to a
different one, disconnect a hook on output leaving it on input only,
prepend/append a filter to existing list of filters.

Now it possible for a single packet filter to provide multiple rulesets
that may be linked to different points. Think of per-interface ACLs in
Cisco or Juniper. None of existing packet filters yet support that,
however limited usage is already possible, e.g. default ruleset can
be moved to single interface, as soon as interface would pride their
filtering points.

Another future feature is possiblity to create pfil heads, that provide
not an mbuf pointer but just a memory pointer with length. That would
allow filtering at very early stages of a packet lifecycle, e.g. when
packet has just been received by a NIC and no mbuf was yet allocated.

Differential Revision:	https://reviews.freebsd.org/D18951
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glebius committed Jan 31, 2019
1 parent 4e4796f commit 9978a7d9242f744fc7473e287332c8df88e33e3e
@@ -38,6 +38,12 @@
# xargs -n1 | sort | uniq -d;
# done

# 20190131: pfil(9) changed
OLD_FILES+=usr/share/man/man9/pfil_hook_get.9
OLD_FILES+=usr/share/man/man9/pfil_rlock.9
OLD_FILES+=usr/share/man/man9/pfil_runlock.9
OLD_FILES+=usr/share/man/man9/pfil_wlock.9
OLD_FILES+=usr/share/man/man9/pfil_wunlock.9
# 20190126: adv(4) / adw(4) removal
OLD_FILES+=usr/share/man/man4/adv.4.gz
OLD_FILES+=usr/share/man/man4/adw.4.gz
@@ -52,6 +52,7 @@ SUBDIR=adjkerntz \
newfs_msdos \
nfsiod \
nos-tun \
pfilctl \
ping \
rcorder \
reboot \
@@ -0,0 +1,9 @@
# $FreeBSD$

PROG= pfilctl
SRCS= pfilctl.c
WARNS?= 6

MAN= pfilctl.8

.include <bsd.prog.mk>
@@ -0,0 +1,117 @@
.\" Copyright (c) 2019 Gleb Smirnoff <glebius@FreeBSD.org>
.\"
.\" 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.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
.\"
.\" $FreeBSD$
.\"
.Dd January 28, 2019
.Dt PFILCTL 8
.Os
.Sh NAME
.Nm pfilctl
.Nd pfil(9) control utility
.Sh SYNOPSIS
.Nm
.Cm heads
.Nm
.Cm hooks
.Nm
.Cm link
.Aq Fl i | Fl o
.Op Fl a
.Ar hook Ar head
.Nm
.Cm unlink
.Aq Fl i | Fl o
.Ar hook Ar head
.Sh DESCRIPTION
The
.Nm
utility is intended to view and change configuration of the
.Xr pfil 9
packet filtering hooks and filters on them.
.Sh COMMANDS
.Bl -tag -width "unlink"
.It Cm heads
List available packet filtering points.
.It Cm hooks
List available packet filters.
.It Xo
.Cm link
.Aq Fl i | Fl o
.Op Fl a
.Ar hook Ar head
.Xc
Link
.Ar hook
to
.Ar head .
With the
.Fl i
flag the hook will be connected as input and with
.Fl o
as output hook.
At least one of
.Fl i
or
.Fl o
is required.
By default
.Nm
will prepend the hook in front of other hooks if any present:
new hook will be as close to the wire as possible, so that on input
it will be the first filter and on output it will be the last.
Adding the
.Fl a
flag switches to appending new hook instead of prepending.
.It Xo
.Cm unlink
.Aq Fl i | Fl o
.Ar hook Ar head
.Xc
Unlink
.Ar hook
on
.Ar head .
At least one of
.Fl i
or
.Fl o
is required.
With the
.Fl i
flag the hook will be removed from the input list of hooks
and with
.Fl o
on output list.
.El
.Sh SEE ALSO
.Xr ipfilter 4 ,
.Xr ipfw 4 ,
.Xr pf 4 ,
.Xr pfil 9
.Sh AUTHORS
.An -nosplit
The
.Nm
utility was written by
.An Gleb Smirnoff Aq Mt glebius@FreeBSD.org .
@@ -0,0 +1,230 @@
/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2019 Gleb Smirnoff <glebius@FreeBSD.org>
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
*/

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/param.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <net/pfil.h>

#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static int dev;

static const char * const typenames[] = {
[PFIL_TYPE_IP4] = "IPv4",
[PFIL_TYPE_IP6] = "IPv6",
[PFIL_TYPE_ETHERNET] = "Ethernet",
};

static void listheads(int argc, char *argv[]);
static void listhooks(int argc, char *argv[]);
static void hook(int argc, char *argv[]);
static void help(void);

static const struct cmd {
const char *cmd_name;
void (*cmd_func)(int argc, char *argv[]);
} cmds[] = {
{ "heads", listheads },
{ "hooks", listhooks },
{ "link", hook },
{ "unlink", hook },
{ NULL, NULL },
};

int
main(int argc __unused, char *argv[] __unused)
{
int cmd = -1;

if (--argc == 0)
help();
argv++;

for (int i = 0; cmds[i].cmd_name != NULL; i++)
if (!strncmp(argv[0], cmds[i].cmd_name, strlen(argv[0]))) {
if (cmd != -1)
errx(1, "ambiguous command: %s", argv[0]);
cmd = i;
}
if (cmd == -1)
errx(1, "unknown command: %s", argv[0]);

dev = open("/dev/" PFILDEV, O_RDWR);
if (dev == -1)
err(1, "open(%s)", "/dev/" PFILDEV);

(*cmds[cmd].cmd_func)(argc, argv);

return (0);
}

static void
help(void)
{
extern char *__progname;

fprintf(stderr, "usage: %s (heads|hooks|link|unlink)\n", __progname);
exit(0);
}

static void
listheads(int argc __unused, char *argv[] __unused)
{
struct pfilioc_list plh;
u_int nheads, nhooks, i;
int j, h;

plh.pio_nheads = 0;
plh.pio_nhooks = 0;
if (ioctl(dev, PFILIOC_LISTHEADS, &plh) != 0)
err(1, "ioctl(PFILIOC_LISTHEADS)");

retry:
plh.pio_heads = calloc(plh.pio_nheads, sizeof(struct pfilioc_head));
if (plh.pio_heads == NULL)
err(1, "malloc");
plh.pio_hooks = calloc(plh.pio_nhooks, sizeof(struct pfilioc_hook));
if (plh.pio_hooks == NULL)
err(1, "malloc");

nheads = plh.pio_nheads;
nhooks = plh.pio_nhooks;

if (ioctl(dev, PFILIOC_LISTHEADS, &plh) != 0)
err(1, "ioctl(PFILIOC_LISTHEADS)");

if (plh.pio_nheads > nheads || plh.pio_nhooks > nhooks) {
free(plh.pio_heads);
free(plh.pio_hooks);
goto retry;
}

#define FMTHD "%16s %8s\n"
#define FMTHK "%29s %16s %16s\n"
printf(FMTHD, "Intercept point", "Type");
for (i = 0, h = 0; i < plh.pio_nheads; i++) {
printf(FMTHD, plh.pio_heads[i].pio_name,
typenames[plh.pio_heads[i].pio_type]);
for (j = 0; j < plh.pio_heads[i].pio_nhooksin; j++, h++)
printf(FMTHK, "In", plh.pio_hooks[h].pio_module,
plh.pio_hooks[h].pio_ruleset);
for (j = 0; j < plh.pio_heads[i].pio_nhooksout; j++, h++)
printf(FMTHK, "Out", plh.pio_hooks[h].pio_module,
plh.pio_hooks[h].pio_ruleset);
}
}

static void
listhooks(int argc __unused, char *argv[] __unused)
{
struct pfilioc_list plh;
u_int nhooks, i;

plh.pio_nhooks = 0;
if (ioctl(dev, PFILIOC_LISTHEADS, &plh) != 0)
err(1, "ioctl(PFILIOC_LISTHEADS)");
retry:
plh.pio_hooks = calloc(plh.pio_nhooks, sizeof(struct pfilioc_hook));
if (plh.pio_hooks == NULL)
err(1, "malloc");

nhooks = plh.pio_nhooks;

if (ioctl(dev, PFILIOC_LISTHOOKS, &plh) != 0)
err(1, "ioctl(PFILIOC_LISTHOOKS)");

if (plh.pio_nhooks > nhooks) {
free(plh.pio_hooks);
goto retry;
}

printf("Available hooks:\n");
for (i = 0; i < plh.pio_nhooks; i++) {
printf("\t%s:%s %s\n", plh.pio_hooks[i].pio_module,
plh.pio_hooks[i].pio_ruleset,
typenames[plh.pio_hooks[i].pio_type]);
}
}

static void
hook(int argc, char *argv[])
{
struct pfilioc_link req;
int c;
char *ruleset;

if (argv[0][0] == 'u')
req.pio_flags = PFIL_UNLINK;
else
req.pio_flags = 0;

while ((c = getopt(argc, argv, "ioa")) != -1)
switch (c) {
case 'i':
req.pio_flags |= PFIL_IN;
break;
case 'o':
req.pio_flags |= PFIL_OUT;
break;
case 'a':
req.pio_flags |= PFIL_APPEND;
break;
default:
help();
}

if (!PFIL_DIR(req.pio_flags))
help();

argc -= optind;
argv += optind;

if (argc != 2)
help();

/* link mod:ruleset head */
if ((ruleset = strchr(argv[0], ':')) == NULL)
help();
*ruleset = '\0';
ruleset++;

strlcpy(req.pio_name, argv[1], sizeof(req.pio_name));
strlcpy(req.pio_module, argv[0], sizeof(req.pio_module));
strlcpy(req.pio_ruleset, ruleset, sizeof(req.pio_ruleset));

if (ioctl(dev, PFILIOC_LINK, &req) != 0)
err(1, "ioctl(PFILIOC_LINK)");
}
@@ -1635,13 +1635,9 @@ MLINKS+=pci_iov_schema.9 pci_iov_schema_alloc_node.9 \
MLINKS+=pfil.9 pfil_add_hook.9 \
pfil.9 pfil_head_register.9 \
pfil.9 pfil_head_unregister.9 \
pfil.9 pfil_hook_get.9 \
pfil.9 pfil_remove_hook.9 \
pfil.9 pfil_rlock.9 \
pfil.9 pfil_run_hooks.9 \
pfil.9 pfil_runlock.9 \
pfil.9 pfil_wlock.9 \
pfil.9 pfil_wunlock.9
pfil.9 pfil_link.9
MLINKS+=pfind.9 zpfind.9
MLINKS+=PHOLD.9 PRELE.9 \
PHOLD.9 _PHOLD.9 \
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