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linux-2.6/net/bridge/br_netfilter.c
Patrick McHardy 2e2f7aefa8 [NETFILTER]: Fix fragmentation issues with bridge netfilter
The conntrack code doesn't do re-fragmentation of defragmented packets
anymore but relies on fragmentation in the IP layer. Purely bridged
packets don't pass through the IP layer, so the bridge netfilter code
needs to take care of fragmentation itself.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-04-09 22:25:23 -07:00

1120 lines
30 KiB
C

/*
* Handle firewalling
* Linux ethernet bridge
*
* Authors:
* Lennert Buytenhek <buytenh@gnu.org>
* Bart De Schuymer (maintainer) <bdschuym@pandora.be>
*
* Changes:
* Apr 29 2003: physdev module support (bdschuym)
* Jun 19 2003: let arptables see bridged ARP traffic (bdschuym)
* Oct 06 2003: filter encapsulated IP/ARP VLAN traffic on untagged bridge
* (bdschuym)
* Sep 01 2004: add IPv6 filtering (bdschuym)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Lennert dedicates this file to Kerstin Wurdinger.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/ip.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <linux/netfilter_bridge.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv6.h>
#include <linux/netfilter_arp.h>
#include <linux/in_route.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/route.h>
#include <asm/uaccess.h>
#include <asm/checksum.h>
#include "br_private.h"
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
#endif
#define skb_origaddr(skb) (((struct bridge_skb_cb *) \
(skb->nf_bridge->data))->daddr.ipv4)
#define store_orig_dstaddr(skb) (skb_origaddr(skb) = (skb)->nh.iph->daddr)
#define dnat_took_place(skb) (skb_origaddr(skb) != (skb)->nh.iph->daddr)
#ifdef CONFIG_SYSCTL
static struct ctl_table_header *brnf_sysctl_header;
static int brnf_call_iptables = 1;
static int brnf_call_ip6tables = 1;
static int brnf_call_arptables = 1;
static int brnf_filter_vlan_tagged = 1;
#else
#define brnf_filter_vlan_tagged 1
#endif
static __be16 inline vlan_proto(const struct sk_buff *skb)
{
return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
}
#define IS_VLAN_IP(skb) \
(skb->protocol == htons(ETH_P_8021Q) && \
vlan_proto(skb) == htons(ETH_P_IP) && \
brnf_filter_vlan_tagged)
#define IS_VLAN_IPV6(skb) \
(skb->protocol == htons(ETH_P_8021Q) && \
vlan_proto(skb) == htons(ETH_P_IPV6) &&\
brnf_filter_vlan_tagged)
#define IS_VLAN_ARP(skb) \
(skb->protocol == htons(ETH_P_8021Q) && \
vlan_proto(skb) == htons(ETH_P_ARP) && \
brnf_filter_vlan_tagged)
/* We need these fake structures to make netfilter happy --
* lots of places assume that skb->dst != NULL, which isn't
* all that unreasonable.
*
* Currently, we fill in the PMTU entry because netfilter
* refragmentation needs it, and the rt_flags entry because
* ipt_REJECT needs it. Future netfilter modules might
* require us to fill additional fields. */
static struct net_device __fake_net_device = {
.hard_header_len = ETH_HLEN
};
static struct rtable __fake_rtable = {
.u = {
.dst = {
.__refcnt = ATOMIC_INIT(1),
.dev = &__fake_net_device,
.path = &__fake_rtable.u.dst,
.metrics = {[RTAX_MTU - 1] = 1500},
.flags = DST_NOXFRM,
}
},
.rt_flags = 0,
};
static inline struct net_device *bridge_parent(const struct net_device *dev)
{
struct net_bridge_port *port = rcu_dereference(dev->br_port);
return port ? port->br->dev : NULL;
}
static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
{
skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
if (likely(skb->nf_bridge))
atomic_set(&(skb->nf_bridge->use), 1);
return skb->nf_bridge;
}
static inline void nf_bridge_save_header(struct sk_buff *skb)
{
int header_size = 16;
if (skb->protocol == htons(ETH_P_8021Q))
header_size = 18;
memcpy(skb->nf_bridge->data, skb->data - header_size, header_size);
}
/* PF_BRIDGE/PRE_ROUTING *********************************************/
/* Undo the changes made for ip6tables PREROUTING and continue the
* bridge PRE_ROUTING hook. */
static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
{
struct nf_bridge_info *nf_bridge = skb->nf_bridge;
if (nf_bridge->mask & BRNF_PKT_TYPE) {
skb->pkt_type = PACKET_OTHERHOST;
nf_bridge->mask ^= BRNF_PKT_TYPE;
}
nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
skb->dst = (struct dst_entry *)&__fake_rtable;
dst_hold(skb->dst);
skb->dev = nf_bridge->physindev;
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_push(skb, VLAN_HLEN);
skb->nh.raw -= VLAN_HLEN;
}
NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
br_handle_frame_finish, 1);
return 0;
}
static void __br_dnat_complain(void)
{
static unsigned long last_complaint;
if (jiffies - last_complaint >= 5 * HZ) {
printk(KERN_WARNING "Performing cross-bridge DNAT requires IP "
"forwarding to be enabled\n");
last_complaint = jiffies;
}
}
/* This requires some explaining. If DNAT has taken place,
* we will need to fix up the destination Ethernet address,
* and this is a tricky process.
*
* There are two cases to consider:
* 1. The packet was DNAT'ed to a device in the same bridge
* port group as it was received on. We can still bridge
* the packet.
* 2. The packet was DNAT'ed to a different device, either
* a non-bridged device or another bridge port group.
* The packet will need to be routed.
*
* The correct way of distinguishing between these two cases is to
* call ip_route_input() and to look at skb->dst->dev, which is
* changed to the destination device if ip_route_input() succeeds.
*
* Let us first consider the case that ip_route_input() succeeds:
*
* If skb->dst->dev equals the logical bridge device the packet
* came in on, we can consider this bridging. We then call
* skb->dst->output() which will make the packet enter br_nf_local_out()
* not much later. In that function it is assured that the iptables
* FORWARD chain is traversed for the packet.
*
* Otherwise, the packet is considered to be routed and we just
* change the destination MAC address so that the packet will
* later be passed up to the IP stack to be routed.
*
* Let us now consider the case that ip_route_input() fails:
*
* After a "echo '0' > /proc/sys/net/ipv4/ip_forward" ip_route_input()
* will fail, while __ip_route_output_key() will return success. The source
* address for __ip_route_output_key() is set to zero, so __ip_route_output_key
* thinks we're handling a locally generated packet and won't care
* if IP forwarding is allowed. We send a warning message to the users's
* log telling her to put IP forwarding on.
*
* ip_route_input() will also fail if there is no route available.
* In that case we just drop the packet.
*
* --Lennert, 20020411
* --Bart, 20020416 (updated)
* --Bart, 20021007 (updated) */
static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
{
if (skb->pkt_type == PACKET_OTHERHOST) {
skb->pkt_type = PACKET_HOST;
skb->nf_bridge->mask |= BRNF_PKT_TYPE;
}
skb->nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
skb->dev = bridge_parent(skb->dev);
if (!skb->dev)
kfree_skb(skb);
else {
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_pull(skb, VLAN_HLEN);
skb->nh.raw += VLAN_HLEN;
}
skb->dst->output(skb);
}
return 0;
}
static int br_nf_pre_routing_finish(struct sk_buff *skb)
{
struct net_device *dev = skb->dev;
struct iphdr *iph = skb->nh.iph;
struct nf_bridge_info *nf_bridge = skb->nf_bridge;
if (nf_bridge->mask & BRNF_PKT_TYPE) {
skb->pkt_type = PACKET_OTHERHOST;
nf_bridge->mask ^= BRNF_PKT_TYPE;
}
nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
if (dnat_took_place(skb)) {
if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev)) {
struct rtable *rt;
struct flowi fl = {
.nl_u = {
.ip4_u = {
.daddr = iph->daddr,
.saddr = 0,
.tos = RT_TOS(iph->tos) },
},
.proto = 0,
};
if (!ip_route_output_key(&rt, &fl)) {
/* - Bridged-and-DNAT'ed traffic doesn't
* require ip_forwarding.
* - Deal with redirected traffic. */
if (((struct dst_entry *)rt)->dev == dev ||
rt->rt_type == RTN_LOCAL) {
skb->dst = (struct dst_entry *)rt;
goto bridged_dnat;
}
__br_dnat_complain();
dst_release((struct dst_entry *)rt);
}
kfree_skb(skb);
return 0;
} else {
if (skb->dst->dev == dev) {
bridged_dnat:
/* Tell br_nf_local_out this is a
* bridged frame */
nf_bridge->mask |= BRNF_BRIDGED_DNAT;
skb->dev = nf_bridge->physindev;
if (skb->protocol ==
htons(ETH_P_8021Q)) {
skb_push(skb, VLAN_HLEN);
skb->nh.raw -= VLAN_HLEN;
}
NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING,
skb, skb->dev, NULL,
br_nf_pre_routing_finish_bridge,
1);
return 0;
}
memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
skb->pkt_type = PACKET_HOST;
}
} else {
skb->dst = (struct dst_entry *)&__fake_rtable;
dst_hold(skb->dst);
}
skb->dev = nf_bridge->physindev;
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_push(skb, VLAN_HLEN);
skb->nh.raw -= VLAN_HLEN;
}
NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
br_handle_frame_finish, 1);
return 0;
}
/* Some common code for IPv4/IPv6 */
static struct net_device *setup_pre_routing(struct sk_buff *skb)
{
struct nf_bridge_info *nf_bridge = skb->nf_bridge;
if (skb->pkt_type == PACKET_OTHERHOST) {
skb->pkt_type = PACKET_HOST;
nf_bridge->mask |= BRNF_PKT_TYPE;
}
nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
nf_bridge->physindev = skb->dev;
skb->dev = bridge_parent(skb->dev);
return skb->dev;
}
/* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
static int check_hbh_len(struct sk_buff *skb)
{
unsigned char *raw = (u8 *) (skb->nh.ipv6h + 1);
u32 pkt_len;
int off = raw - skb->nh.raw;
int len = (raw[1] + 1) << 3;
if ((raw + len) - skb->data > skb_headlen(skb))
goto bad;
off += 2;
len -= 2;
while (len > 0) {
int optlen = skb->nh.raw[off + 1] + 2;
switch (skb->nh.raw[off]) {
case IPV6_TLV_PAD0:
optlen = 1;
break;
case IPV6_TLV_PADN:
break;
case IPV6_TLV_JUMBO:
if (skb->nh.raw[off + 1] != 4 || (off & 3) != 2)
goto bad;
pkt_len = ntohl(*(u32 *) (skb->nh.raw + off + 2));
if (pkt_len <= IPV6_MAXPLEN ||
skb->nh.ipv6h->payload_len)
goto bad;
if (pkt_len > skb->len - sizeof(struct ipv6hdr))
goto bad;
if (pskb_trim_rcsum(skb,
pkt_len + sizeof(struct ipv6hdr)))
goto bad;
break;
default:
if (optlen > len)
goto bad;
break;
}
off += optlen;
len -= optlen;
}
if (len == 0)
return 0;
bad:
return -1;
}
/* Replicate the checks that IPv6 does on packet reception and pass the packet
* to ip6tables, which doesn't support NAT, so things are fairly simple. */
static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct ipv6hdr *hdr;
u32 pkt_len;
if (skb->len < sizeof(struct ipv6hdr))
goto inhdr_error;
if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
goto inhdr_error;
hdr = skb->nh.ipv6h;
if (hdr->version != 6)
goto inhdr_error;
pkt_len = ntohs(hdr->payload_len);
if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
goto inhdr_error;
if (pkt_len + sizeof(struct ipv6hdr) < skb->len) {
if (__pskb_trim(skb, pkt_len + sizeof(struct ipv6hdr)))
goto inhdr_error;
if (skb->ip_summed == CHECKSUM_HW)
skb->ip_summed = CHECKSUM_NONE;
}
}
if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
goto inhdr_error;
nf_bridge_put(skb->nf_bridge);
if (!nf_bridge_alloc(skb))
return NF_DROP;
if (!setup_pre_routing(skb))
return NF_DROP;
NF_HOOK(PF_INET6, NF_IP6_PRE_ROUTING, skb, skb->dev, NULL,
br_nf_pre_routing_finish_ipv6);
return NF_STOLEN;
inhdr_error:
return NF_DROP;
}
/* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
* Replicate the checks that IPv4 does on packet reception.
* Set skb->dev to the bridge device (i.e. parent of the
* receiving device) to make netfilter happy, the REDIRECT
* target in particular. Save the original destination IP
* address to be able to detect DNAT afterwards. */
static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct iphdr *iph;
__u32 len;
struct sk_buff *skb = *pskb;
if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb)) {
#ifdef CONFIG_SYSCTL
if (!brnf_call_ip6tables)
return NF_ACCEPT;
#endif
if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)
goto out;
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_pull_rcsum(skb, VLAN_HLEN);
skb->nh.raw += VLAN_HLEN;
}
return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
}
#ifdef CONFIG_SYSCTL
if (!brnf_call_iptables)
return NF_ACCEPT;
#endif
if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb))
return NF_ACCEPT;
if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)
goto out;
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_pull_rcsum(skb, VLAN_HLEN);
skb->nh.raw += VLAN_HLEN;
}
if (!pskb_may_pull(skb, sizeof(struct iphdr)))
goto inhdr_error;
iph = skb->nh.iph;
if (iph->ihl < 5 || iph->version != 4)
goto inhdr_error;
if (!pskb_may_pull(skb, 4 * iph->ihl))
goto inhdr_error;
iph = skb->nh.iph;
if (ip_fast_csum((__u8 *) iph, iph->ihl) != 0)
goto inhdr_error;
len = ntohs(iph->tot_len);
if (skb->len < len || len < 4 * iph->ihl)
goto inhdr_error;
if (skb->len > len) {
__pskb_trim(skb, len);
if (skb->ip_summed == CHECKSUM_HW)
skb->ip_summed = CHECKSUM_NONE;
}
nf_bridge_put(skb->nf_bridge);
if (!nf_bridge_alloc(skb))
return NF_DROP;
if (!setup_pre_routing(skb))
return NF_DROP;
store_orig_dstaddr(skb);
NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
br_nf_pre_routing_finish);
return NF_STOLEN;
inhdr_error:
// IP_INC_STATS_BH(IpInHdrErrors);
out:
return NF_DROP;
}
/* PF_BRIDGE/LOCAL_IN ************************************************/
/* The packet is locally destined, which requires a real
* dst_entry, so detach the fake one. On the way up, the
* packet would pass through PRE_ROUTING again (which already
* took place when the packet entered the bridge), but we
* register an IPv4 PRE_ROUTING 'sabotage' hook that will
* prevent this from happening. */
static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct sk_buff *skb = *pskb;
if (skb->dst == (struct dst_entry *)&__fake_rtable) {
dst_release(skb->dst);
skb->dst = NULL;
}
return NF_ACCEPT;
}
/* PF_BRIDGE/FORWARD *************************************************/
static int br_nf_forward_finish(struct sk_buff *skb)
{
struct nf_bridge_info *nf_bridge = skb->nf_bridge;
struct net_device *in;
if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
in = nf_bridge->physindev;
if (nf_bridge->mask & BRNF_PKT_TYPE) {
skb->pkt_type = PACKET_OTHERHOST;
nf_bridge->mask ^= BRNF_PKT_TYPE;
}
} else {
in = *((struct net_device **)(skb->cb));
}
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_push(skb, VLAN_HLEN);
skb->nh.raw -= VLAN_HLEN;
}
NF_HOOK_THRESH(PF_BRIDGE, NF_BR_FORWARD, skb, in,
skb->dev, br_forward_finish, 1);
return 0;
}
/* This is the 'purely bridged' case. For IP, we pass the packet to
* netfilter with indev and outdev set to the bridge device,
* but we are still able to filter on the 'real' indev/outdev
* because of the physdev module. For ARP, indev and outdev are the
* bridge ports. */
static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct sk_buff *skb = *pskb;
struct nf_bridge_info *nf_bridge;
struct net_device *parent;
int pf;
if (!skb->nf_bridge)
return NF_ACCEPT;
parent = bridge_parent(out);
if (!parent)
return NF_DROP;
if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb))
pf = PF_INET;
else
pf = PF_INET6;
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_pull(*pskb, VLAN_HLEN);
(*pskb)->nh.raw += VLAN_HLEN;
}
nf_bridge = skb->nf_bridge;
if (skb->pkt_type == PACKET_OTHERHOST) {
skb->pkt_type = PACKET_HOST;
nf_bridge->mask |= BRNF_PKT_TYPE;
}
/* The physdev module checks on this */
nf_bridge->mask |= BRNF_BRIDGED;
nf_bridge->physoutdev = skb->dev;
NF_HOOK(pf, NF_IP_FORWARD, skb, bridge_parent(in), parent,
br_nf_forward_finish);
return NF_STOLEN;
}
static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct sk_buff *skb = *pskb;
struct net_device **d = (struct net_device **)(skb->cb);
#ifdef CONFIG_SYSCTL
if (!brnf_call_arptables)
return NF_ACCEPT;
#endif
if (skb->protocol != htons(ETH_P_ARP)) {
if (!IS_VLAN_ARP(skb))
return NF_ACCEPT;
skb_pull(*pskb, VLAN_HLEN);
(*pskb)->nh.raw += VLAN_HLEN;
}
if (skb->nh.arph->ar_pln != 4) {
if (IS_VLAN_ARP(skb)) {
skb_push(*pskb, VLAN_HLEN);
(*pskb)->nh.raw -= VLAN_HLEN;
}
return NF_ACCEPT;
}
*d = (struct net_device *)in;
NF_HOOK(NF_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
(struct net_device *)out, br_nf_forward_finish);
return NF_STOLEN;
}
/* PF_BRIDGE/LOCAL_OUT ***********************************************/
static int br_nf_local_out_finish(struct sk_buff *skb)
{
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_push(skb, VLAN_HLEN);
skb->nh.raw -= VLAN_HLEN;
}
NF_HOOK_THRESH(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
br_forward_finish, NF_BR_PRI_FIRST + 1);
return 0;
}
/* This function sees both locally originated IP packets and forwarded
* IP packets (in both cases the destination device is a bridge
* device). It also sees bridged-and-DNAT'ed packets.
* To be able to filter on the physical bridge devices (with the physdev
* module), we steal packets destined to a bridge device away from the
* PF_INET/FORWARD and PF_INET/OUTPUT hook functions, and give them back later,
* when we have determined the real output device. This is done in here.
*
* If (nf_bridge->mask & BRNF_BRIDGED_DNAT) then the packet is bridged
* and we fake the PF_BRIDGE/FORWARD hook. The function br_nf_forward()
* will then fake the PF_INET/FORWARD hook. br_nf_local_out() has priority
* NF_BR_PRI_FIRST, so no relevant PF_BRIDGE/INPUT functions have been nor
* will be executed.
* Otherwise, if nf_bridge->physindev is NULL, the bridge-nf code never touched
* this packet before, and so the packet was locally originated. We fake
* the PF_INET/LOCAL_OUT hook.
* Finally, if nf_bridge->physindev isn't NULL, then the packet was IP routed,
* so we fake the PF_INET/FORWARD hook. ip_sabotage_out() makes sure
* even routed packets that didn't arrive on a bridge interface have their
* nf_bridge->physindev set. */
static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct net_device *realindev, *realoutdev;
struct sk_buff *skb = *pskb;
struct nf_bridge_info *nf_bridge;
int pf;
if (!skb->nf_bridge)
return NF_ACCEPT;
if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb))
pf = PF_INET;
else
pf = PF_INET6;
#ifdef CONFIG_NETFILTER_DEBUG
/* Sometimes we get packets with NULL ->dst here (for example,
* running a dhcp client daemon triggers this). This should now
* be fixed, but let's keep the check around. */
if (skb->dst == NULL) {
printk(KERN_CRIT "br_netfilter: skb->dst == NULL.");
return NF_ACCEPT;
}
#endif
nf_bridge = skb->nf_bridge;
nf_bridge->physoutdev = skb->dev;
realindev = nf_bridge->physindev;
/* Bridged, take PF_BRIDGE/FORWARD.
* (see big note in front of br_nf_pre_routing_finish) */
if (nf_bridge->mask & BRNF_BRIDGED_DNAT) {
if (nf_bridge->mask & BRNF_PKT_TYPE) {
skb->pkt_type = PACKET_OTHERHOST;
nf_bridge->mask ^= BRNF_PKT_TYPE;
}
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_push(skb, VLAN_HLEN);
skb->nh.raw -= VLAN_HLEN;
}
NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, realindev,
skb->dev, br_forward_finish);
goto out;
}
realoutdev = bridge_parent(skb->dev);
if (!realoutdev)
return NF_DROP;
#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
/* iptables should match -o br0.x */
if (nf_bridge->netoutdev)
realoutdev = nf_bridge->netoutdev;
#endif
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_pull(skb, VLAN_HLEN);
(*pskb)->nh.raw += VLAN_HLEN;
}
/* IP forwarded traffic has a physindev, locally
* generated traffic hasn't. */
if (realindev != NULL) {
if (!(nf_bridge->mask & BRNF_DONT_TAKE_PARENT)) {
struct net_device *parent = bridge_parent(realindev);
if (parent)
realindev = parent;
}
NF_HOOK_THRESH(pf, NF_IP_FORWARD, skb, realindev,
realoutdev, br_nf_local_out_finish,
NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD + 1);
} else {
NF_HOOK_THRESH(pf, NF_IP_LOCAL_OUT, skb, realindev,
realoutdev, br_nf_local_out_finish,
NF_IP_PRI_BRIDGE_SABOTAGE_LOCAL_OUT + 1);
}
out:
return NF_STOLEN;
}
static int br_nf_dev_queue_xmit(struct sk_buff *skb)
{
if (skb->protocol == htons(ETH_P_IP) &&
skb->len > skb->dev->mtu &&
!(skb_shinfo(skb)->ufo_size || skb_shinfo(skb)->tso_size))
return ip_fragment(skb, br_dev_queue_push_xmit);
else
return br_dev_queue_push_xmit(skb);
}
/* PF_BRIDGE/POST_ROUTING ********************************************/
static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct sk_buff *skb = *pskb;
struct nf_bridge_info *nf_bridge = (*pskb)->nf_bridge;
struct net_device *realoutdev = bridge_parent(skb->dev);
int pf;
#ifdef CONFIG_NETFILTER_DEBUG
/* Be very paranoid. This probably won't happen anymore, but let's
* keep the check just to be sure... */
if (skb->mac.raw < skb->head || skb->mac.raw + ETH_HLEN > skb->data) {
printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: "
"bad mac.raw pointer.");
goto print_error;
}
#endif
if (!nf_bridge)
return NF_ACCEPT;
if (!realoutdev)
return NF_DROP;
if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb))
pf = PF_INET;
else
pf = PF_INET6;
#ifdef CONFIG_NETFILTER_DEBUG
if (skb->dst == NULL) {
printk(KERN_CRIT "br_netfilter: skb->dst == NULL.");
goto print_error;
}
#endif
/* We assume any code from br_dev_queue_push_xmit onwards doesn't care
* about the value of skb->pkt_type. */
if (skb->pkt_type == PACKET_OTHERHOST) {
skb->pkt_type = PACKET_HOST;
nf_bridge->mask |= BRNF_PKT_TYPE;
}
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_pull(skb, VLAN_HLEN);
skb->nh.raw += VLAN_HLEN;
}
nf_bridge_save_header(skb);
#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
if (nf_bridge->netoutdev)
realoutdev = nf_bridge->netoutdev;
#endif
NF_HOOK(pf, NF_IP_POST_ROUTING, skb, NULL, realoutdev,
br_nf_dev_queue_xmit);
return NF_STOLEN;
#ifdef CONFIG_NETFILTER_DEBUG
print_error:
if (skb->dev != NULL) {
printk("[%s]", skb->dev->name);
if (realoutdev)
printk("[%s]", realoutdev->name);
}
printk(" head:%p, raw:%p, data:%p\n", skb->head, skb->mac.raw,
skb->data);
return NF_ACCEPT;
#endif
}
/* IP/SABOTAGE *****************************************************/
/* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
* for the second time. */
static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
if ((*pskb)->nf_bridge &&
!((*pskb)->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
return NF_STOP;
}
return NF_ACCEPT;
}
/* Postpone execution of PF_INET(6)/FORWARD, PF_INET(6)/LOCAL_OUT
* and PF_INET(6)/POST_ROUTING until we have done the forwarding
* decision in the bridge code and have determined nf_bridge->physoutdev. */
static unsigned int ip_sabotage_out(unsigned int hook, struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct sk_buff *skb = *pskb;
if ((out->hard_start_xmit == br_dev_xmit &&
okfn != br_nf_forward_finish &&
okfn != br_nf_local_out_finish && okfn != br_nf_dev_queue_xmit)
#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
|| ((out->priv_flags & IFF_802_1Q_VLAN) &&
VLAN_DEV_INFO(out)->real_dev->hard_start_xmit == br_dev_xmit)
#endif
) {
struct nf_bridge_info *nf_bridge;
if (!skb->nf_bridge) {
#ifdef CONFIG_SYSCTL
/* This code is executed while in the IP(v6) stack,
the version should be 4 or 6. We can't use
skb->protocol because that isn't set on
PF_INET(6)/LOCAL_OUT. */
struct iphdr *ip = skb->nh.iph;
if (ip->version == 4 && !brnf_call_iptables)
return NF_ACCEPT;
else if (ip->version == 6 && !brnf_call_ip6tables)
return NF_ACCEPT;
#endif
if (hook == NF_IP_POST_ROUTING)
return NF_ACCEPT;
if (!nf_bridge_alloc(skb))
return NF_DROP;
}
nf_bridge = skb->nf_bridge;
/* This frame will arrive on PF_BRIDGE/LOCAL_OUT and we
* will need the indev then. For a brouter, the real indev
* can be a bridge port, so we make sure br_nf_local_out()
* doesn't use the bridge parent of the indev by using
* the BRNF_DONT_TAKE_PARENT mask. */
if (hook == NF_IP_FORWARD && nf_bridge->physindev == NULL) {
nf_bridge->mask |= BRNF_DONT_TAKE_PARENT;
nf_bridge->physindev = (struct net_device *)in;
}
#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
/* the iptables outdev is br0.x, not br0 */
if (out->priv_flags & IFF_802_1Q_VLAN)
nf_bridge->netoutdev = (struct net_device *)out;
#endif
return NF_STOP;
}
return NF_ACCEPT;
}
/* For br_nf_local_out we need (prio = NF_BR_PRI_FIRST), to insure that innocent
* PF_BRIDGE/NF_BR_LOCAL_OUT functions don't get bridged traffic as input.
* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
* ip_refrag() can return NF_STOLEN. */
static struct nf_hook_ops br_nf_ops[] = {
{ .hook = br_nf_pre_routing,
.owner = THIS_MODULE,
.pf = PF_BRIDGE,
.hooknum = NF_BR_PRE_ROUTING,
.priority = NF_BR_PRI_BRNF, },
{ .hook = br_nf_local_in,
.owner = THIS_MODULE,
.pf = PF_BRIDGE,
.hooknum = NF_BR_LOCAL_IN,
.priority = NF_BR_PRI_BRNF, },
{ .hook = br_nf_forward_ip,
.owner = THIS_MODULE,
.pf = PF_BRIDGE,
.hooknum = NF_BR_FORWARD,
.priority = NF_BR_PRI_BRNF - 1, },
{ .hook = br_nf_forward_arp,
.owner = THIS_MODULE,
.pf = PF_BRIDGE,
.hooknum = NF_BR_FORWARD,
.priority = NF_BR_PRI_BRNF, },
{ .hook = br_nf_local_out,
.owner = THIS_MODULE,
.pf = PF_BRIDGE,
.hooknum = NF_BR_LOCAL_OUT,
.priority = NF_BR_PRI_FIRST, },
{ .hook = br_nf_post_routing,
.owner = THIS_MODULE,
.pf = PF_BRIDGE,
.hooknum = NF_BR_POST_ROUTING,
.priority = NF_BR_PRI_LAST, },
{ .hook = ip_sabotage_in,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_IP_PRE_ROUTING,
.priority = NF_IP_PRI_FIRST, },
{ .hook = ip_sabotage_in,
.owner = THIS_MODULE,
.pf = PF_INET6,
.hooknum = NF_IP6_PRE_ROUTING,
.priority = NF_IP6_PRI_FIRST, },
{ .hook = ip_sabotage_out,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_IP_FORWARD,
.priority = NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD, },
{ .hook = ip_sabotage_out,
.owner = THIS_MODULE,
.pf = PF_INET6,
.hooknum = NF_IP6_FORWARD,
.priority = NF_IP6_PRI_BRIDGE_SABOTAGE_FORWARD, },
{ .hook = ip_sabotage_out,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_IP_LOCAL_OUT,
.priority = NF_IP_PRI_BRIDGE_SABOTAGE_LOCAL_OUT, },
{ .hook = ip_sabotage_out,
.owner = THIS_MODULE,
.pf = PF_INET6,
.hooknum = NF_IP6_LOCAL_OUT,
.priority = NF_IP6_PRI_BRIDGE_SABOTAGE_LOCAL_OUT, },
{ .hook = ip_sabotage_out,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_IP_POST_ROUTING,
.priority = NF_IP_PRI_FIRST, },
{ .hook = ip_sabotage_out,
.owner = THIS_MODULE,
.pf = PF_INET6,
.hooknum = NF_IP6_POST_ROUTING,
.priority = NF_IP6_PRI_FIRST, },
};
#ifdef CONFIG_SYSCTL
static
int brnf_sysctl_call_tables(ctl_table * ctl, int write, struct file *filp,
void __user * buffer, size_t * lenp, loff_t * ppos)
{
int ret;
ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
if (write && *(int *)(ctl->data))
*(int *)(ctl->data) = 1;
return ret;
}
static ctl_table brnf_table[] = {
{
.ctl_name = NET_BRIDGE_NF_CALL_ARPTABLES,
.procname = "bridge-nf-call-arptables",
.data = &brnf_call_arptables,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &brnf_sysctl_call_tables,
},
{
.ctl_name = NET_BRIDGE_NF_CALL_IPTABLES,
.procname = "bridge-nf-call-iptables",
.data = &brnf_call_iptables,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &brnf_sysctl_call_tables,
},
{
.ctl_name = NET_BRIDGE_NF_CALL_IP6TABLES,
.procname = "bridge-nf-call-ip6tables",
.data = &brnf_call_ip6tables,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &brnf_sysctl_call_tables,
},
{
.ctl_name = NET_BRIDGE_NF_FILTER_VLAN_TAGGED,
.procname = "bridge-nf-filter-vlan-tagged",
.data = &brnf_filter_vlan_tagged,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &brnf_sysctl_call_tables,
},
{ .ctl_name = 0 }
};
static ctl_table brnf_bridge_table[] = {
{
.ctl_name = NET_BRIDGE,
.procname = "bridge",
.mode = 0555,
.child = brnf_table,
},
{ .ctl_name = 0 }
};
static ctl_table brnf_net_table[] = {
{
.ctl_name = CTL_NET,
.procname = "net",
.mode = 0555,
.child = brnf_bridge_table,
},
{ .ctl_name = 0 }
};
#endif
int br_netfilter_init(void)
{
int i;
for (i = 0; i < ARRAY_SIZE(br_nf_ops); i++) {
int ret;
if ((ret = nf_register_hook(&br_nf_ops[i])) >= 0)
continue;
while (i--)
nf_unregister_hook(&br_nf_ops[i]);
return ret;
}
#ifdef CONFIG_SYSCTL
brnf_sysctl_header = register_sysctl_table(brnf_net_table, 0);
if (brnf_sysctl_header == NULL) {
printk(KERN_WARNING
"br_netfilter: can't register to sysctl.\n");
for (i = 0; i < ARRAY_SIZE(br_nf_ops); i++)
nf_unregister_hook(&br_nf_ops[i]);
return -EFAULT;
}
#endif
printk(KERN_NOTICE "Bridge firewalling registered\n");
return 0;
}
void br_netfilter_fini(void)
{
int i;
for (i = ARRAY_SIZE(br_nf_ops) - 1; i >= 0; i--)
nf_unregister_hook(&br_nf_ops[i]);
#ifdef CONFIG_SYSCTL
unregister_sysctl_table(brnf_sysctl_header);
#endif
}