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/*
* Forwarding decision
* 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/err.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/if_vlan.h>
#include <linux/netfilter_bridge.h>
#include "br_private.h"
/* Don't forward packets to originating port or forwarding diasabled */
static inline int should_deliver(const struct net_bridge_port *p,
const struct sk_buff *skb)
{
return (((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
p->state == BR_STATE_FORWARDING);
}
static inline unsigned packet_length(const struct sk_buff *skb)
{
return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
}
int br_dev_queue_push_xmit(struct sk_buff *skb)
{
/* drop mtu oversized packets except gso */
if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
kfree_skb(skb);
else {
/* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
if (nf_bridge_maybe_copy_header(skb))
kfree_skb(skb);
else {
skb_push(skb, ETH_HLEN);
dev_queue_xmit(skb);
}
}
return 0;
}
int br_forward_finish(struct sk_buff *skb)
{
return NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
br_dev_queue_push_xmit);
}
static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
{
skb->dev = to->dev;
NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
br_forward_finish);
}
static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
{
struct net_device *indev;
if (skb_warn_if_lro(skb)) {
kfree_skb(skb);
return;
}
indev = skb->dev;
skb->dev = to->dev;
skb_forward_csum(skb);
NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
br_forward_finish);
}
/* called with rcu_read_lock */
void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
{
if (should_deliver(to, skb)) {
__br_deliver(to, skb);
return;
}
kfree_skb(skb);
}
/* called with rcu_read_lock */
void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
{
if (should_deliver(to, skb)) {
__br_forward(to, skb);
return;
}
kfree_skb(skb);
}
static int deliver_clone(struct net_bridge_port *prev, struct sk_buff *skb,
void (*__packet_hook)(const struct net_bridge_port *p,
struct sk_buff *skb))
{
skb = skb_clone(skb, GFP_ATOMIC);
if (!skb) {
struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
dev->stats.tx_dropped++;
return -ENOMEM;
}
__packet_hook(prev, skb);
return 0;
}
static struct net_bridge_port *maybe_deliver(
struct net_bridge_port *prev, struct net_bridge_port *p,
struct sk_buff *skb,
void (*__packet_hook)(const struct net_bridge_port *p,
struct sk_buff *skb))
{
int err;
if (!should_deliver(p, skb))
return prev;
if (!prev)
goto out;
err = deliver_clone(prev, skb, __packet_hook);
if (err)
return ERR_PTR(err);
out:
return p;
}
/* called under bridge lock */
static void br_flood(struct net_bridge *br, struct sk_buff *skb,
struct sk_buff *skb0,
void (*__packet_hook)(const struct net_bridge_port *p,
struct sk_buff *skb))
{
struct net_bridge_port *p;
struct net_bridge_port *prev;
prev = NULL;
list_for_each_entry_rcu(p, &br->port_list, list) {
prev = maybe_deliver(prev, p, skb, __packet_hook);
if (IS_ERR(prev))
goto out;
}
if (!prev)
goto out;
if (skb0)
deliver_clone(prev, skb, __packet_hook);
else
__packet_hook(prev, skb);
return;
out:
if (!skb0)
kfree_skb(skb);
}
/* called with rcu_read_lock */
void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb)
{
br_flood(br, skb, NULL, __br_deliver);
}
/* called under bridge lock */
void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
struct sk_buff *skb2)
{
br_flood(br, skb, skb2, __br_forward);
}
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