/*
* 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/neighbour.h>
#include <net/arp.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_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
{
return netif_receive_skb(skb);
}
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 net_bridge_vlan_group *vg;
struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
u64_stats_update_begin(&brstats->syncp);
brstats->rx_packets++;
brstats->rx_bytes += skb->len;
u64_stats_update_end(&brstats->syncp);
vg = br_vlan_group_rcu(br);
/* Bridge is just like any other port. Make sure the
* packet is allowed except in promisc modue when someone
* may be running packet capture.
*/
if (!(brdev->flags & IFF_PROMISC) &&
!br_allowed_egress(vg, skb)) {
kfree_skb(skb);
return NET_RX_DROP;
}
indev = skb->dev;
skb->dev = brdev;
skb = br_handle_vlan(br, vg, skb);
if (!skb)
return NET_RX_DROP;
/* update the multicast stats if the packet is IGMP/MLD */
br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
BR_MCAST_DIR_TX);
return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
dev_net(indev), NULL, skb, indev, NULL,
br_netif_receive_skb);
}
static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br,
u16 vid, struct net_bridge_port *p)
{
struct net_device *dev = br->dev;
struct neighbour *n;
struct arphdr *parp;
u8 *arpptr, *sha;
__be32 sip, tip;
BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
if ((dev->flags & IFF_NOARP) ||
!pskb_may_pull(skb, arp_hdr_len(dev)))
return;
parp = arp_hdr(skb);
if (parp->ar_pro != htons(ETH_P_IP) ||
parp->ar_op != htons(ARPOP_REQUEST) ||
parp->ar_hln != dev->addr_len ||
parp->ar_pln != 4)
return;
arpptr = (u8 *)parp + sizeof(struct arphdr);
sha = arpptr;
arpptr += dev->addr_len; /* sha */
memcpy(&sip, arpptr, sizeof(sip));
arpptr += sizeof(sip);
arpptr += dev->addr_len; /* tha */
memcpy(&tip, arpptr, sizeof(tip));
if (ipv4_is_loopback(tip) ||
ipv4_is_multicast(tip))
return;
n = neigh_lookup(&arp_tbl, &tip, dev);
if (n) {
struct net_bridge_fdb_entry *f;
if (!(n->nud_state & NUD_VALID)) {
neigh_release(n);
return;
}
f = __br_fdb_get(br, n->ha, vid);
if (f && ((p->flags & BR_PROXYARP) ||
(f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) {
arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip,
sha, n->ha, sha);
BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
}
neigh_release(n);
}
}
/* note: already called with rcu_read_lock */
int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
{
struct net_bridge_port *p = br_port_get_rcu(skb->dev);
const unsigned char *dest = eth_hdr(skb)->h_dest;
enum br_pkt_type pkt_type = BR_PKT_UNICAST;
struct net_bridge_fdb_entry *dst = NULL;
struct net_bridge_mdb_entry *mdst;
bool local_rcv, mcast_hit = false;
struct net_bridge *br;
u16 vid = 0;
if (!p || p->state == BR_STATE_DISABLED)
goto drop;
if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid))
goto out;
nbp_switchdev_frame_mark(p, skb);
/* 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);
local_rcv = !!(br->dev->flags & IFF_PROMISC);
if (is_multicast_ether_addr(dest)) {
/* by definition the broadcast is also a multicast address */
if (is_broadcast_ether_addr(dest)) {
pkt_type = BR_PKT_BROADCAST;
local_rcv = true;
} else {
pkt_type = BR_PKT_MULTICAST;
if (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;
if (IS_ENABLED([31mCONFIG_INET[0m) && skb->protocol == htons(ETH_P_ARP))
br_do_proxy_arp(skb, br, vid, p);
switch (pkt_type) {
case BR_PKT_MULTICAST:
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)) {
local_rcv = true;
br->dev->stats.multicast++;
}
mcast_hit = true;
} else {
local_rcv = true;
br->dev->stats.multicast++;
}
break;
case BR_PKT_UNICAST:
dst = __br_fdb_get(br, dest, vid);
default:
break;
}
if (dst) {
if (dst->is_local)
return br_pass_frame_up(skb);
dst->used = jiffies;
br_forward(dst->dst, skb, local_rcv, false);
} else {
if (!mcast_hit)
br_flood(br, skb, pkt_type, local_rcv, false);
else
br_multicast_flood(mdst, skb, local_rcv, false);
}
if (local_rcv)
return br_pass_frame_up(skb);
out:
return 0;
drop:
kfree_skb(skb);
goto out;
}
EXPORT_SYMBOL_GPL(br_handle_frame_finish);
static void __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);
}
/* note: already called with rcu_read_lock */
static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
{
struct net_bridge_port *p = br_port_get_rcu(skb->dev);
__br_handle_local_finish(skb);
BR_INPUT_SKB_CB(skb)->brdev = p->br->dev;
br_pass_frame_up(skb);
return 0;
}
/*
* 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;
*pskb = skb;
__br_handle_local_finish(skb);
return RX_HANDLER_PASS;
case 0x01: /* IEEE MAC (Pause) */
goto drop;
case 0x0E: /* 802.1AB LLDP */
fwd_mask |= p->br->group_fwd_mask;
if (fwd_mask & (1u << dest[5]))
goto forward;
*pskb = skb;
__br_handle_local_finish(skb);
return RX_HANDLER_PASS;
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 */
NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev),
NULL, skb, skb->dev, NULL, br_handle_local_finish);
return RX_HANDLER_CONSUMED;
}
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,
dev_net(skb->dev), NULL, skb, skb->dev, NULL,
br_handle_frame_finish);
break;
default:
drop:
kfree_skb(skb);
}
return RX_HANDLER_CONSUMED;
}