linux/net/bridge/br_input.c
Pablo Neira Ayuso 34666d467c netfilter: bridge: move br_netfilter out of the core
Jesper reported that br_netfilter always registers the hooks since
this is part of the bridge core. This harms performance for people that
don't need this.

This patch modularizes br_netfilter so it can be rmmod'ed, thus,
the hooks can be unregistered. I think the bridge netfilter should have
been a separated module since the beginning, Patrick agreed on that.

Note that this is breaking compatibility for users that expect that
bridge netfilter is going to be available after explicitly 'modprobe
bridge' or via automatic load through brctl.

However, the damage can be easily undone by modprobing br_netfilter.
The bridge core also spots a message to provide a clue to people that
didn't notice that this has been deprecated.

On top of that, the plan is that nftables will not rely on this software
layer, but integrate the connection tracking into the bridge layer to
enable stateful filtering and NAT, which is was bridge netfilter users
seem to require.

This patch still keeps the fake_dst_ops in the bridge core, since this
is required by when the bridge port is initialized. So we can safely
modprobe/rmmod br_netfilter anytime.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Florian Westphal <fw@strlen.de>
2014-09-26 18:42:31 +02:00

250 lines
6.1 KiB
C

/*
* Handle incoming frames
* Linux ethernet bridge
*
* Authors:
* Lennert Buytenhek <buytenh@gnu.org>
*
* 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.
*/
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/netfilter_bridge.h>
#include <linux/export.h>
#include <linux/rculist.h>
#include "br_private.h"
/* Hook for brouter */
br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
EXPORT_SYMBOL(br_should_route_hook);
static int br_pass_frame_up(struct sk_buff *skb)
{
struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
struct net_bridge *br = netdev_priv(brdev);
struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
struct net_port_vlans *pv;
u64_stats_update_begin(&brstats->syncp);
brstats->rx_packets++;
brstats->rx_bytes += skb->len;
u64_stats_update_end(&brstats->syncp);
/* Bridge is just like any other port. Make sure the
* packet is allowed except in promisc modue when someone
* may be running packet capture.
*/
pv = br_get_vlan_info(br);
if (!(brdev->flags & IFF_PROMISC) &&
!br_allowed_egress(br, pv, skb)) {
kfree_skb(skb);
return NET_RX_DROP;
}
indev = skb->dev;
skb->dev = brdev;
skb = br_handle_vlan(br, pv, skb);
if (!skb)
return NET_RX_DROP;
return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
netif_receive_skb);
}
/* note: already called with rcu_read_lock */
int br_handle_frame_finish(struct sk_buff *skb)
{
const unsigned char *dest = eth_hdr(skb)->h_dest;
struct net_bridge_port *p = br_port_get_rcu(skb->dev);
struct net_bridge *br;
struct net_bridge_fdb_entry *dst;
struct net_bridge_mdb_entry *mdst;
struct sk_buff *skb2;
bool unicast = true;
u16 vid = 0;
if (!p || p->state == BR_STATE_DISABLED)
goto drop;
if (!br_allowed_ingress(p->br, nbp_get_vlan_info(p), skb, &vid))
goto out;
/* insert into forwarding database after filtering to avoid spoofing */
br = p->br;
if (p->flags & BR_LEARNING)
br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false);
if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&
br_multicast_rcv(br, p, skb, vid))
goto drop;
if (p->state == BR_STATE_LEARNING)
goto drop;
BR_INPUT_SKB_CB(skb)->brdev = br->dev;
/* The packet skb2 goes to the local host (NULL to skip). */
skb2 = NULL;
if (br->dev->flags & IFF_PROMISC)
skb2 = skb;
dst = NULL;
if (is_broadcast_ether_addr(dest)) {
skb2 = skb;
unicast = false;
} else if (is_multicast_ether_addr(dest)) {
mdst = br_mdb_get(br, skb, vid);
if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
br_multicast_querier_exists(br, eth_hdr(skb))) {
if ((mdst && mdst->mglist) ||
br_multicast_is_router(br))
skb2 = skb;
br_multicast_forward(mdst, skb, skb2);
skb = NULL;
if (!skb2)
goto out;
} else
skb2 = skb;
unicast = false;
br->dev->stats.multicast++;
} else if ((dst = __br_fdb_get(br, dest, vid)) &&
dst->is_local) {
skb2 = skb;
/* Do not forward the packet since it's local. */
skb = NULL;
}
if (skb) {
if (dst) {
dst->used = jiffies;
br_forward(dst->dst, skb, skb2);
} else
br_flood_forward(br, skb, skb2, unicast);
}
if (skb2)
return br_pass_frame_up(skb2);
out:
return 0;
drop:
kfree_skb(skb);
goto out;
}
EXPORT_SYMBOL_GPL(br_handle_frame_finish);
/* note: already called with rcu_read_lock */
static int br_handle_local_finish(struct sk_buff *skb)
{
struct net_bridge_port *p = br_port_get_rcu(skb->dev);
u16 vid = 0;
/* check if vlan is allowed, to avoid spoofing */
if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid))
br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false);
return 0; /* process further */
}
/*
* Return NULL if skb is handled
* note: already called with rcu_read_lock
*/
rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
{
struct net_bridge_port *p;
struct sk_buff *skb = *pskb;
const unsigned char *dest = eth_hdr(skb)->h_dest;
br_should_route_hook_t *rhook;
if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
return RX_HANDLER_PASS;
if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
goto drop;
skb = skb_share_check(skb, GFP_ATOMIC);
if (!skb)
return RX_HANDLER_CONSUMED;
p = br_port_get_rcu(skb->dev);
if (unlikely(is_link_local_ether_addr(dest))) {
u16 fwd_mask = p->br->group_fwd_mask_required;
/*
* See IEEE 802.1D Table 7-10 Reserved addresses
*
* Assignment Value
* Bridge Group Address 01-80-C2-00-00-00
* (MAC Control) 802.3 01-80-C2-00-00-01
* (Link Aggregation) 802.3 01-80-C2-00-00-02
* 802.1X PAE address 01-80-C2-00-00-03
*
* 802.1AB LLDP 01-80-C2-00-00-0E
*
* Others reserved for future standardization
*/
switch (dest[5]) {
case 0x00: /* Bridge Group Address */
/* If STP is turned off,
then must forward to keep loop detection */
if (p->br->stp_enabled == BR_NO_STP ||
fwd_mask & (1u << dest[5]))
goto forward;
break;
case 0x01: /* IEEE MAC (Pause) */
goto drop;
default:
/* Allow selective forwarding for most other protocols */
fwd_mask |= p->br->group_fwd_mask;
if (fwd_mask & (1u << dest[5]))
goto forward;
}
/* Deliver packet to local host only */
if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
NULL, br_handle_local_finish)) {
return RX_HANDLER_CONSUMED; /* consumed by filter */
} else {
*pskb = skb;
return RX_HANDLER_PASS; /* continue processing */
}
}
forward:
switch (p->state) {
case BR_STATE_FORWARDING:
rhook = rcu_dereference(br_should_route_hook);
if (rhook) {
if ((*rhook)(skb)) {
*pskb = skb;
return RX_HANDLER_PASS;
}
dest = eth_hdr(skb)->h_dest;
}
/* fall through */
case BR_STATE_LEARNING:
if (ether_addr_equal(p->br->dev->dev_addr, dest))
skb->pkt_type = PACKET_HOST;
NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
br_handle_frame_finish);
break;
default:
drop:
kfree_skb(skb);
}
return RX_HANDLER_CONSUMED;
}