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freebsd/sys/netinet/ip_fw_pfil.c
Paolo Pisati ff2f6fe80f Summer of Code 2005: improve libalias - part 2 of 2 
With the second (and last) part of my previous Summer of Code work, we get:

-ipfw's in kernel nat

-redirect_* and LSNAT support

General information about nat syntax and some examples are available
in the ipfw (8) man page. The redirect and LSNAT syntax are identical
to natd, so please refer to natd (8) man page.

To enable in kernel nat in rc.conf, two options were added:

o firewall_nat_enable: equivalent to natd_enable

o firewall_nat_interface: equivalent to natd_interface

Remember to set net.inet.ip.fw.one_pass to 0, if you want the packet
to continue being checked by the firewall ruleset after being
(de)aliased.

NOTA BENE: due to some problems with libalias architecture, in kernel
nat won't work with TSO enabled nic, thus you have to disable TSO via
ifconfig (ifconfig foo0 -tso).

Approved by: glebius (mentor)
2006-12-29 21:59:17 +00:00

568 lines
12 KiB
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/*-
* Copyright (c) 2004 Andre Oppermann, Internet Business Solutions AG
* 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.
*
* 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.
*
* $FreeBSD$
*/
#if !defined(KLD_MODULE)
#include "opt_ipfw.h"
#include "opt_ipdn.h"
#include "opt_inet.h"
#ifndef INET
#error IPFIREWALL requires INET.
#endif /* INET */
#endif /* KLD_MODULE */
#include "opt_inet6.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/module.h>
#include <sys/kernel.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#include <sys/ucred.h>
#include <net/if.h>
#include <net/route.h>
#include <net/pfil.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/ip_fw.h>
#include <netinet/ip_divert.h>
#include <netinet/ip_dummynet.h>
#include <netgraph/ng_ipfw.h>
#include <machine/in_cksum.h>
int fw_enable = 1;
#ifdef INET6
int fw6_enable = 1;
#endif
int ipfw_chg_hook(SYSCTL_HANDLER_ARGS);
/* Dummynet hooks. */
ip_dn_ruledel_t *ip_dn_ruledel_ptr = NULL;
/* Divert hooks. */
ip_divert_packet_t *ip_divert_ptr = NULL;
/* ng_ipfw hooks. */
ng_ipfw_input_t *ng_ipfw_input_p = NULL;
/* Forward declarations. */
static int ipfw_divert(struct mbuf **, int, int);
#define DIV_DIR_IN 1
#define DIV_DIR_OUT 0
int
ipfw_check_in(void *arg, struct mbuf **m0, struct ifnet *ifp, int dir,
struct inpcb *inp)
{
struct ip_fw_args args;
struct ng_ipfw_tag *ng_tag;
struct m_tag *dn_tag;
int ipfw = 0;
int divert;
int tee;
#ifdef IPFIREWALL_FORWARD
struct m_tag *fwd_tag;
#endif
KASSERT(dir == PFIL_IN, ("ipfw_check_in wrong direction!"));
bzero(&args, sizeof(args));
dn_tag = m_tag_find(*m0, PACKET_TAG_DUMMYNET, NULL);
if (dn_tag != NULL){
struct dn_pkt_tag *dt;
dt = (struct dn_pkt_tag *)(dn_tag+1);
args.rule = dt->rule;
m_tag_delete(*m0, dn_tag);
}
ng_tag = (struct ng_ipfw_tag *)m_tag_locate(*m0, NGM_IPFW_COOKIE, 0,
NULL);
if (ng_tag != NULL) {
KASSERT(ng_tag->dir == NG_IPFW_IN,
("ng_ipfw tag with wrong direction"));
args.rule = ng_tag->rule;
m_tag_delete(*m0, (struct m_tag *)ng_tag);
}
again:
args.m = *m0;
args.inp = inp;
ipfw = ipfw_chk(&args);
*m0 = args.m;
tee = 0;
KASSERT(*m0 != NULL || ipfw == IP_FW_DENY, ("%s: m0 is NULL",
__func__));
switch (ipfw) {
case IP_FW_PASS:
if (args.next_hop == NULL)
goto pass;
#ifdef IPFIREWALL_FORWARD
fwd_tag = m_tag_get(PACKET_TAG_IPFORWARD,
sizeof(struct sockaddr_in), M_NOWAIT);
if (fwd_tag == NULL)
goto drop;
bcopy(args.next_hop, (fwd_tag+1), sizeof(struct sockaddr_in));
m_tag_prepend(*m0, fwd_tag);
if (in_localip(args.next_hop->sin_addr))
(*m0)->m_flags |= M_FASTFWD_OURS;
goto pass;
#endif
break; /* not reached */
case IP_FW_DENY:
goto drop;
break; /* not reached */
case IP_FW_DUMMYNET:
if (!DUMMYNET_LOADED)
goto drop;
if (mtod(*m0, struct ip *)->ip_v == 4)
ip_dn_io_ptr(*m0, DN_TO_IP_IN, &args);
else if (mtod(*m0, struct ip *)->ip_v == 6)
ip_dn_io_ptr(*m0, DN_TO_IP6_IN, &args);
*m0 = NULL;
return 0; /* packet consumed */
case IP_FW_TEE:
tee = 1;
/* fall through */
case IP_FW_DIVERT:
divert = ipfw_divert(m0, DIV_DIR_IN, tee);
if (divert) {
*m0 = NULL;
return 0; /* packet consumed */
} else {
args.rule = NULL;
goto again; /* continue with packet */
}
case IP_FW_NGTEE:
if (!NG_IPFW_LOADED)
goto drop;
(void)ng_ipfw_input_p(m0, NG_IPFW_IN, &args, 1);
goto again; /* continue with packet */
case IP_FW_NETGRAPH:
if (!NG_IPFW_LOADED)
goto drop;
return ng_ipfw_input_p(m0, NG_IPFW_IN, &args, 0);
case IP_FW_NAT:
goto again; /* continue with packet */
default:
KASSERT(0, ("%s: unknown retval", __func__));
}
drop:
if (*m0)
m_freem(*m0);
*m0 = NULL;
return (EACCES);
pass:
return 0; /* not filtered */
}
int
ipfw_check_out(void *arg, struct mbuf **m0, struct ifnet *ifp, int dir,
struct inpcb *inp)
{
struct ip_fw_args args;
struct ng_ipfw_tag *ng_tag;
struct m_tag *dn_tag;
int ipfw = 0;
int divert;
int tee;
#ifdef IPFIREWALL_FORWARD
struct m_tag *fwd_tag;
#endif
KASSERT(dir == PFIL_OUT, ("ipfw_check_out wrong direction!"));
bzero(&args, sizeof(args));
dn_tag = m_tag_find(*m0, PACKET_TAG_DUMMYNET, NULL);
if (dn_tag != NULL) {
struct dn_pkt_tag *dt;
dt = (struct dn_pkt_tag *)(dn_tag+1);
args.rule = dt->rule;
m_tag_delete(*m0, dn_tag);
}
ng_tag = (struct ng_ipfw_tag *)m_tag_locate(*m0, NGM_IPFW_COOKIE, 0,
NULL);
if (ng_tag != NULL) {
KASSERT(ng_tag->dir == NG_IPFW_OUT,
("ng_ipfw tag with wrong direction"));
args.rule = ng_tag->rule;
m_tag_delete(*m0, (struct m_tag *)ng_tag);
}
again:
args.m = *m0;
args.oif = ifp;
args.inp = inp;
ipfw = ipfw_chk(&args);
*m0 = args.m;
tee = 0;
KASSERT(*m0 != NULL || ipfw == IP_FW_DENY, ("%s: m0 is NULL",
__func__));
switch (ipfw) {
case IP_FW_PASS:
if (args.next_hop == NULL)
goto pass;
#ifdef IPFIREWALL_FORWARD
/* Overwrite existing tag. */
fwd_tag = m_tag_find(*m0, PACKET_TAG_IPFORWARD, NULL);
if (fwd_tag == NULL) {
fwd_tag = m_tag_get(PACKET_TAG_IPFORWARD,
sizeof(struct sockaddr_in), M_NOWAIT);
if (fwd_tag == NULL)
goto drop;
} else
m_tag_unlink(*m0, fwd_tag);
bcopy(args.next_hop, (fwd_tag+1), sizeof(struct sockaddr_in));
m_tag_prepend(*m0, fwd_tag);
if (in_localip(args.next_hop->sin_addr))
(*m0)->m_flags |= M_FASTFWD_OURS;
goto pass;
#endif
break; /* not reached */
case IP_FW_DENY:
goto drop;
break; /* not reached */
case IP_FW_DUMMYNET:
if (!DUMMYNET_LOADED)
break;
if (mtod(*m0, struct ip *)->ip_v == 4)
ip_dn_io_ptr(*m0, DN_TO_IP_OUT, &args);
else if (mtod(*m0, struct ip *)->ip_v == 6)
ip_dn_io_ptr(*m0, DN_TO_IP6_OUT, &args);
*m0 = NULL;
return 0; /* packet consumed */
break;
case IP_FW_TEE:
tee = 1;
/* fall through */
case IP_FW_DIVERT:
divert = ipfw_divert(m0, DIV_DIR_OUT, tee);
if (divert) {
*m0 = NULL;
return 0; /* packet consumed */
} else {
args.rule = NULL;
goto again; /* continue with packet */
}
case IP_FW_NGTEE:
if (!NG_IPFW_LOADED)
goto drop;
(void)ng_ipfw_input_p(m0, NG_IPFW_OUT, &args, 1);
goto again; /* continue with packet */
case IP_FW_NETGRAPH:
if (!NG_IPFW_LOADED)
goto drop;
return ng_ipfw_input_p(m0, NG_IPFW_OUT, &args, 0);
case IP_FW_NAT:
goto again; /* continue with packet */
default:
KASSERT(0, ("%s: unknown retval", __func__));
}
drop:
if (*m0)
m_freem(*m0);
*m0 = NULL;
return (EACCES);
pass:
return 0; /* not filtered */
}
static int
ipfw_divert(struct mbuf **m, int incoming, int tee)
{
/*
* ipfw_chk() has already tagged the packet with the divert tag.
* If tee is set, copy packet and return original.
* If not tee, consume packet and send it to divert socket.
*/
struct mbuf *clone, *reass;
struct ip *ip;
int hlen;
reass = NULL;
/* Is divert module loaded? */
if (ip_divert_ptr == NULL)
goto nodivert;
/* Cloning needed for tee? */
if (tee)
clone = m_dup(*m, M_DONTWAIT);
else
clone = *m;
/* In case m_dup was unable to allocate mbufs. */
if (clone == NULL)
goto teeout;
/*
* Divert listeners can only handle non-fragmented packets.
* However when tee is set we will *not* de-fragment the packets;
* Doing do would put the reassembly into double-jeopardy. On top
* of that someone doing a tee will probably want to get the packet
* in its original form.
*/
ip = mtod(clone, struct ip *);
if (!tee && ip->ip_off & (IP_MF | IP_OFFMASK)) {
/* Reassemble packet. */
reass = ip_reass(clone);
/*
* IP header checksum fixup after reassembly and leave header
* in network byte order.
*/
if (reass != NULL) {
ip = mtod(reass, struct ip *);
hlen = ip->ip_hl << 2;
ip->ip_len = htons(ip->ip_len);
ip->ip_off = htons(ip->ip_off);
ip->ip_sum = 0;
if (hlen == sizeof(struct ip))
ip->ip_sum = in_cksum_hdr(ip);
else
ip->ip_sum = in_cksum(reass, hlen);
clone = reass;
} else
clone = NULL;
} else {
/* Convert header to network byte order. */
ip->ip_len = htons(ip->ip_len);
ip->ip_off = htons(ip->ip_off);
}
/* Do the dirty job... */
if (clone && ip_divert_ptr != NULL)
ip_divert_ptr(clone, incoming);
teeout:
/*
* For tee we leave the divert tag attached to original packet.
* It will then continue rule evaluation after the tee rule.
*/
if (tee)
return 0;
/* Packet diverted and consumed */
return 1;
nodivert:
m_freem(*m);
return 1;
}
static int
ipfw_hook(void)
{
struct pfil_head *pfh_inet;
pfh_inet = pfil_head_get(PFIL_TYPE_AF, AF_INET);
if (pfh_inet == NULL)
return ENOENT;
pfil_add_hook(ipfw_check_in, NULL, PFIL_IN | PFIL_WAITOK, pfh_inet);
pfil_add_hook(ipfw_check_out, NULL, PFIL_OUT | PFIL_WAITOK, pfh_inet);
return 0;
}
static int
ipfw_unhook(void)
{
struct pfil_head *pfh_inet;
pfh_inet = pfil_head_get(PFIL_TYPE_AF, AF_INET);
if (pfh_inet == NULL)
return ENOENT;
pfil_remove_hook(ipfw_check_in, NULL, PFIL_IN | PFIL_WAITOK, pfh_inet);
pfil_remove_hook(ipfw_check_out, NULL, PFIL_OUT | PFIL_WAITOK, pfh_inet);
return 0;
}
#ifdef INET6
static int
ipfw6_hook(void)
{
struct pfil_head *pfh_inet6;
pfh_inet6 = pfil_head_get(PFIL_TYPE_AF, AF_INET6);
if (pfh_inet6 == NULL)
return ENOENT;
pfil_add_hook(ipfw_check_in, NULL, PFIL_IN | PFIL_WAITOK, pfh_inet6);
pfil_add_hook(ipfw_check_out, NULL, PFIL_OUT | PFIL_WAITOK, pfh_inet6);
return 0;
}
static int
ipfw6_unhook(void)
{
struct pfil_head *pfh_inet6;
pfh_inet6 = pfil_head_get(PFIL_TYPE_AF, AF_INET6);
if (pfh_inet6 == NULL)
return ENOENT;
pfil_remove_hook(ipfw_check_in, NULL, PFIL_IN | PFIL_WAITOK, pfh_inet6);
pfil_remove_hook(ipfw_check_out, NULL, PFIL_OUT | PFIL_WAITOK, pfh_inet6);
return 0;
}
#endif /* INET6 */
int
ipfw_chg_hook(SYSCTL_HANDLER_ARGS)
{
int enable = *(int *)arg1;
int error;
error = sysctl_handle_int(oidp, &enable, 0, req);
if (error)
return (error);
enable = (enable) ? 1 : 0;
if (enable == *(int *)arg1)
return (0);
if (arg1 == &fw_enable) {
if (enable)
error = ipfw_hook();
else
error = ipfw_unhook();
}
#ifdef INET6
if (arg1 == &fw6_enable) {
if (enable)
error = ipfw6_hook();
else
error = ipfw6_unhook();
}
#endif
if (error)
return (error);
*(int *)arg1 = enable;
return (0);
}
static int
ipfw_modevent(module_t mod, int type, void *unused)
{
int err = 0;
switch (type) {
case MOD_LOAD:
if ((err = ipfw_init()) != 0) {
printf("ipfw_init() error\n");
break;
}
if ((err = ipfw_hook()) != 0) {
printf("ipfw_hook() error\n");
break;
}
#ifdef INET6
if ((err = ipfw6_hook()) != 0) {
printf("ipfw_hook() error\n");
break;
}
#endif
break;
case MOD_UNLOAD:
if ((err = ipfw_unhook()) > 0)
break;
#ifdef INET6
if ((err = ipfw6_unhook()) > 0)
break;
#endif
ipfw_destroy();
break;
default:
return EOPNOTSUPP;
break;
}
return err;
}
static moduledata_t ipfwmod = {
"ipfw",
ipfw_modevent,
0
};
DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY);
MODULE_VERSION(ipfw, 2);
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