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DEFINITIONS
This source file includes following definitions.
- vlan_proto
- pppoe_proto
- br_netfilter_rtable_init
- bridge_parent_rtable
- bridge_parent
- nf_bridge_alloc
- nf_bridge_unshare
- nf_bridge_push_encap_header
- nf_bridge_pull_encap_header
- nf_bridge_pull_encap_header_rcsum
- nf_bridge_save_header
- nf_bridge_copy_header
- br_nf_pre_routing_finish_ipv6
- __br_dnat_complain
- br_nf_pre_routing_finish_bridge
- br_nf_pre_routing_finish
- setup_pre_routing
- check_hbh_len
- br_nf_pre_routing_ipv6
- br_nf_pre_routing
- br_nf_local_in
- br_nf_forward_finish
- br_nf_forward_ip
- br_nf_forward_arp
- br_nf_local_out
- br_nf_dev_queue_xmit
- br_nf_post_routing
- ip_sabotage_in
- brnf_sysctl_call_tables
- br_netfilter_init
- br_netfilter_fini
/*
* 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/if_pppox.h>
#include <linux/ppp_defs.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 <linux/inetdevice.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/route.h>
#include <asm/uaccess.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) = ip_hdr(skb)->daddr)
#define dnat_took_place(skb) (skb_origaddr(skb) != ip_hdr(skb)->daddr)
#ifdef CONFIG_SYSCTL
static struct ctl_table_header *brnf_sysctl_header;
static int brnf_call_iptables __read_mostly = 1;
static int brnf_call_ip6tables __read_mostly = 1;
static int brnf_call_arptables __read_mostly = 1;
static int brnf_filter_vlan_tagged __read_mostly = 1;
static int brnf_filter_pppoe_tagged __read_mostly = 1;
#else
#define brnf_filter_vlan_tagged 1
#define brnf_filter_pppoe_tagged 1
#endif
static inline __be16 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)
static inline __be16 pppoe_proto(const struct sk_buff *skb)
{
return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
sizeof(struct pppoe_hdr)));
}
#define IS_PPPOE_IP(skb) \
(skb->protocol == htons(ETH_P_PPP_SES) && \
pppoe_proto(skb) == htons(PPP_IP) && \
brnf_filter_pppoe_tagged)
#define IS_PPPOE_IPV6(skb) \
(skb->protocol == htons(ETH_P_PPP_SES) && \
pppoe_proto(skb) == htons(PPP_IPV6) && \
brnf_filter_pppoe_tagged)
/*
* Initialize bogus route table used to keep netfilter happy.
* 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.
*/
void br_netfilter_rtable_init(struct net_bridge *br)
{
struct rtable *rt = &br->fake_rtable;
atomic_set(&rt->u.dst.__refcnt, 1);
rt->u.dst.dev = br->dev;
rt->u.dst.path = &rt->u.dst;
rt->u.dst.metrics[RTAX_MTU - 1] = 1500;
rt->u.dst.flags = DST_NOXFRM;
}
static inline struct rtable *bridge_parent_rtable(const struct net_device *dev)
{
struct net_bridge_port *port = rcu_dereference(dev->br_port);
return port ? &port->br->fake_rtable : NULL;
}
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 struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
{
struct nf_bridge_info *nf_bridge = skb->nf_bridge;
if (atomic_read(&nf_bridge->use) > 1) {
struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
if (tmp) {
memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
atomic_set(&tmp->use, 1);
nf_bridge_put(nf_bridge);
}
nf_bridge = tmp;
}
return nf_bridge;
}
static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
{
unsigned int len = nf_bridge_encap_header_len(skb);
skb_push(skb, len);
skb->network_header -= len;
}
static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
{
unsigned int len = nf_bridge_encap_header_len(skb);
skb_pull(skb, len);
skb->network_header += len;
}
static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
{
unsigned int len = nf_bridge_encap_header_len(skb);
skb_pull_rcsum(skb, len);
skb->network_header += len;
}
static inline void nf_bridge_save_header(struct sk_buff *skb)
{
int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
skb_copy_from_linear_data_offset(skb, -header_size,
skb->nf_bridge->data, header_size);
}
/*
* When forwarding bridge frames, we save a copy of the original
* header before processing.
*/
int nf_bridge_copy_header(struct sk_buff *skb)
{
int err;
int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
err = skb_cow_head(skb, header_size);
if (err)
return err;
skb_copy_to_linear_data_offset(skb, -header_size,
skb->nf_bridge->data, header_size);
__skb_push(skb, nf_bridge_encap_header_len(skb));
return 0;
}
/* 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->rtable = bridge_parent_rtable(nf_bridge->physindev);
if (!skb->rtable) {
kfree_skb(skb);
return 0;
}
dst_hold(&skb->rtable->u.dst);
skb->dev = nf_bridge->physindev;
nf_bridge_push_encap_header(skb);
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. The packet is passed
* through the neighbour output function to build a new destination
* MAC address, 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. For a redirected
* packet, ip_route_input() will give back the localhost as output device,
* which differs from the bridge device.
*
* Let us now consider the case that ip_route_input() fails:
*
* This can be because the destination address is martian, in which case
* the packet will be dropped.
* 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)
* --Bart, 20062711 (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) {
struct dst_entry *dst = skb->dst;
nf_bridge_pull_encap_header(skb);
if (dst->hh)
return neigh_hh_output(dst->hh, skb);
else if (dst->neighbour)
return dst->neighbour->output(skb);
}
kfree_skb(skb);
return 0;
}
static int br_nf_pre_routing_finish(struct sk_buff *skb)
{
struct net_device *dev = skb->dev;
struct iphdr *iph = ip_hdr(skb);
struct nf_bridge_info *nf_bridge = skb->nf_bridge;
int err;
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 ((err = 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,
};
struct in_device *in_dev = in_dev_get(dev);
/* If err equals -EHOSTUNREACH the error is due to a
* martian destination or due to the fact that
* forwarding is disabled. For most martian packets,
* ip_route_output_key() will fail. It won't fail for 2 types of
* martian destinations: loopback destinations and destination
* 0.0.0.0. In both cases the packet will be dropped because the
* destination is the loopback device and not the bridge. */
if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
goto free_skb;
if (!ip_route_output_key(&init_net, &rt, &fl)) {
/* - Bridged-and-DNAT'ed traffic doesn't
* require ip_forwarding. */
if (((struct dst_entry *)rt)->dev == dev) {
skb->dst = (struct dst_entry *)rt;
goto bridged_dnat;
}
/* we are sure that forwarding is disabled, so printing
* this message is no problem. Note that the packet could
* still have a martian destination address, in which case
* the packet could be dropped even if forwarding were enabled */
__br_dnat_complain();
dst_release((struct dst_entry *)rt);
}
free_skb:
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;
nf_bridge_push_encap_header(skb);
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->rtable = bridge_parent_rtable(nf_bridge->physindev);
if (!skb->rtable) {
kfree_skb(skb);
return 0;
}
dst_hold(&skb->rtable->u.dst);
}
skb->dev = nf_bridge->physindev;
nf_bridge_push_encap_header(skb);
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 *)(ipv6_hdr(skb) + 1);
u32 pkt_len;
const unsigned char *nh = skb_network_header(skb);
int off = raw - nh;
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 = nh[off + 1] + 2;
switch (nh[off]) {
case IPV6_TLV_PAD0:
optlen = 1;
break;
case IPV6_TLV_PADN:
break;
case IPV6_TLV_JUMBO:
if (nh[off + 1] != 4 || (off & 3) != 2)
goto bad;
pkt_len = ntohl(*(__be32 *) (nh + off + 2));
if (pkt_len <= IPV6_MAXPLEN ||
ipv6_hdr(skb)->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;
nh = skb_network_header(skb);
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 = ipv6_hdr(skb);
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 (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
goto inhdr_error;
}
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_INET_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 *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct iphdr *iph;
__u32 len = nf_bridge_encap_header_len(skb);
if (unlikely(!pskb_may_pull(skb, len)))
goto out;
if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
IS_PPPOE_IPV6(skb)) {
#ifdef CONFIG_SYSCTL
if (!brnf_call_ip6tables)
return NF_ACCEPT;
#endif
nf_bridge_pull_encap_header_rcsum(skb);
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) &&
!IS_PPPOE_IP(skb))
return NF_ACCEPT;
nf_bridge_pull_encap_header_rcsum(skb);
if (!pskb_may_pull(skb, sizeof(struct iphdr)))
goto inhdr_error;
iph = ip_hdr(skb);
if (iph->ihl < 5 || iph->version != 4)
goto inhdr_error;
if (!pskb_may_pull(skb, 4 * iph->ihl))
goto inhdr_error;
iph = ip_hdr(skb);
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;
pskb_trim_rcsum(skb, len);
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_INET_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 *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
if (skb->rtable && skb->rtable == bridge_parent_rtable(in)) {
dst_release(&skb->rtable->u.dst);
skb->rtable = 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));
}
nf_bridge_push_encap_header(skb);
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 *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct nf_bridge_info *nf_bridge;
struct net_device *parent;
u_int8_t pf;
if (!skb->nf_bridge)
return NF_ACCEPT;
/* Need exclusive nf_bridge_info since we might have multiple
* different physoutdevs. */
if (!nf_bridge_unshare(skb))
return NF_DROP;
parent = bridge_parent(out);
if (!parent)
return NF_DROP;
if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
IS_PPPOE_IP(skb))
pf = PF_INET;
else
pf = PF_INET6;
nf_bridge_pull_encap_header(skb);
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_INET_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 *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
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;
nf_bridge_pull_encap_header(skb);
}
if (arp_hdr(skb)->ar_pln != 4) {
if (IS_VLAN_ARP(skb))
nf_bridge_push_encap_header(skb);
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 ***********************************************
*
* 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.
*
* 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.
*/
static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct net_device *realindev;
struct nf_bridge_info *nf_bridge;
if (!skb->nf_bridge)
return NF_ACCEPT;
/* Need exclusive nf_bridge_info since we might have multiple
* different physoutdevs. */
if (!nf_bridge_unshare(skb))
return NF_DROP;
nf_bridge = skb->nf_bridge;
if (!(nf_bridge->mask & BRNF_BRIDGED_DNAT))
return NF_ACCEPT;
/* Bridged, take PF_BRIDGE/FORWARD.
* (see big note in front of br_nf_pre_routing_finish) */
nf_bridge->physoutdev = skb->dev;
realindev = nf_bridge->physindev;
if (nf_bridge->mask & BRNF_PKT_TYPE) {
skb->pkt_type = PACKET_OTHERHOST;
nf_bridge->mask ^= BRNF_PKT_TYPE;
}
nf_bridge_push_encap_header(skb);
NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, realindev, skb->dev,
br_forward_finish);
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_is_gso(skb))
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 *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct nf_bridge_info *nf_bridge = skb->nf_bridge;
struct net_device *realoutdev = bridge_parent(skb->dev);
u_int8_t 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_header(skb) < skb->head ||
skb_mac_header(skb) + ETH_HLEN > skb->data) {
printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: "
"bad mac.raw pointer.\n");
goto print_error;
}
#endif
if (!nf_bridge)
return NF_ACCEPT;
if (!(nf_bridge->mask & (BRNF_BRIDGED | BRNF_BRIDGED_DNAT)))
return NF_ACCEPT;
if (!realoutdev)
return NF_DROP;
if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
IS_PPPOE_IP(skb))
pf = PF_INET;
else
pf = PF_INET6;
#ifdef CONFIG_NETFILTER_DEBUG
if (skb->dst == NULL) {
printk(KERN_INFO "br_netfilter post_routing: skb->dst == NULL\n");
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;
}
nf_bridge_pull_encap_header(skb);
nf_bridge_save_header(skb);
NF_HOOK(pf, NF_INET_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_header(skb),
skb->data);
dump_stack();
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 *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
if (skb->nf_bridge &&
!(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
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[] __read_mostly = {
{ .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_INET_PRE_ROUTING,
.priority = NF_IP_PRI_FIRST, },
{ .hook = ip_sabotage_in,
.owner = THIS_MODULE,
.pf = PF_INET6,
.hooknum = NF_INET_PRE_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[] = {
{
.procname = "bridge-nf-call-arptables",
.data = &brnf_call_arptables,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &brnf_sysctl_call_tables,
},
{
.procname = "bridge-nf-call-iptables",
.data = &brnf_call_iptables,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &brnf_sysctl_call_tables,
},
{
.procname = "bridge-nf-call-ip6tables",
.data = &brnf_call_ip6tables,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &brnf_sysctl_call_tables,
},
{
.procname = "bridge-nf-filter-vlan-tagged",
.data = &brnf_filter_vlan_tagged,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &brnf_sysctl_call_tables,
},
{
.procname = "bridge-nf-filter-pppoe-tagged",
.data = &brnf_filter_pppoe_tagged,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &brnf_sysctl_call_tables,
},
{ .ctl_name = 0 }
};
static struct ctl_path brnf_path[] = {
{ .procname = "net", .ctl_name = CTL_NET, },
{ .procname = "bridge", .ctl_name = NET_BRIDGE, },
{ }
};
#endif
int __init br_netfilter_init(void)
{
int ret;
ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
if (ret < 0)
return ret;
#ifdef CONFIG_SYSCTL
brnf_sysctl_header = register_sysctl_paths(brnf_path, brnf_table);
if (brnf_sysctl_header == NULL) {
printk(KERN_WARNING
"br_netfilter: can't register to sysctl.\n");
nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
return -ENOMEM;
}
#endif
printk(KERN_NOTICE "Bridge firewalling registered\n");
return 0;
}
void br_netfilter_fini(void)
{
nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
#ifdef CONFIG_SYSCTL
unregister_sysctl_table(brnf_sysctl_header);
#endif
}