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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Handle incoming frames
* Linux ethernet bridge
*
* Authors:
* Lennert Buytenhek <buytenh@gnu.org>
*/
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/netfilter_bridge.h>
#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
#include <net/netfilter/nf_queue.h>
#endif
#include <linux/neighbour.h>
#include <net/arp.h>
#include <net/dsa.h>
#include <linux/export.h>
#include <linux/rculist.h>
#include "br_private.h"
#include "br_private_tunnel.h"
static int
br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
{
br_drop_fake_rtable(skb);
return netif_receive_skb(skb);
}
static int br_pass_frame_up(struct sk_buff *skb, bool promisc)
{
struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
struct net_bridge *br = netdev_priv(brdev);
struct net_bridge_vlan_group *vg;
dev_sw_netstats_rx_add(brdev, skb->len);
vg = br_vlan_group_rcu(br);
/* Reset the offload_fwd_mark because there could be a stacked
* bridge above, and it should not think this bridge it doing
* that bridge's work forwarding out its ports.
*/
br_switchdev_frame_unmark(skb);
/* Bridge is just like any other port. Make sure the
* packet is allowed except in promisc mode 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, NULL, 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);
BR_INPUT_SKB_CB(skb)->promisc = promisc;
return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
dev_net(indev), NULL, skb, indev, NULL,
br_netif_receive_skb);
}
/* 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);
enum br_pkt_type pkt_type = BR_PKT_UNICAST;
struct net_bridge_fdb_entry *dst = NULL;
struct net_bridge_mcast_port *pmctx;
struct net_bridge_mdb_entry *mdst;
bool local_rcv, mcast_hit = false;
struct net_bridge_mcast *brmctx;
struct net_bridge_vlan *vlan;
struct net_bridge *br;
bool promisc;
u16 vid = 0;
u8 state;
if (!p)
goto drop;
br = p->br;
if (br_mst_is_enabled(br)) {
state = BR_STATE_FORWARDING;
} else {
if (p->state == BR_STATE_DISABLED)
goto drop;
state = p->state;
}
brmctx = &p->br->multicast_ctx;
pmctx = &p->multicast_ctx;
if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid,
&state, &vlan))
goto out;
if (p->flags & BR_PORT_LOCKED) {
struct net_bridge_fdb_entry *fdb_src =
br_fdb_find_rcu(br, eth_hdr(skb)->h_source, vid);
if (!fdb_src) {
/* FDB miss. Create locked FDB entry if MAB is enabled
* and drop the packet.
*/
if (p->flags & BR_PORT_MAB)
br_fdb_update(br, p, eth_hdr(skb)->h_source,
vid, BIT(BR_FDB_LOCKED));
goto drop;
} else if (READ_ONCE(fdb_src->dst) != p ||
test_bit(BR_FDB_LOCAL, &fdb_src->flags)) {
/* FDB mismatch. Drop the packet without roaming. */
goto drop;
} else if (test_bit(BR_FDB_LOCKED, &fdb_src->flags)) {
/* FDB match, but entry is locked. Refresh it and drop
* the packet.
*/
br_fdb_update(br, p, eth_hdr(skb)->h_source, vid,
BIT(BR_FDB_LOCKED));
goto drop;
}
}
nbp_switchdev_frame_mark(p, skb);
/* insert into forwarding database after filtering to avoid spoofing */
if (p->flags & BR_LEARNING)
br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0);
promisc = !!(br->dev->flags & IFF_PROMISC);
local_rcv = promisc;
if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) {
/* by definition the broadcast is also a multicast address */
if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) {
pkt_type = BR_PKT_BROADCAST;
local_rcv = true;
} else {
pkt_type = BR_PKT_MULTICAST;
if (br_multicast_rcv(&brmctx, &pmctx, vlan, skb, vid))
goto drop;
}
}
if (state == BR_STATE_LEARNING)
goto drop;
BR_INPUT_SKB_CB(skb)->brdev = br->dev;
BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED);
if (IS_ENABLED(CONFIG_INET) &&
(skb->protocol == htons(ETH_P_ARP) ||
skb->protocol == htons(ETH_P_RARP))) {
br_do_proxy_suppress_arp(skb, br, vid, p);
} else if (IS_ENABLED(CONFIG_IPV6) &&
skb->protocol == htons(ETH_P_IPV6) &&
br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
pskb_may_pull(skb, sizeof(struct ipv6hdr) +
sizeof(struct nd_msg)) &&
ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
struct nd_msg *msg, _msg;
msg = br_is_nd_neigh_msg(skb, &_msg);
if (msg)
br_do_suppress_nd(skb, br, vid, p, msg);
}
switch (pkt_type) {
case BR_PKT_MULTICAST:
mdst = br_mdb_entry_skb_get(brmctx, skb, vid);
if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) {
if ((mdst && mdst->host_joined) ||
br_multicast_is_router(brmctx, skb)) {
local_rcv = true;
DEV_STATS_INC(br->dev, multicast);
}
mcast_hit = true;
} else {
local_rcv = true;
DEV_STATS_INC(br->dev, multicast);
}
break;
case BR_PKT_UNICAST:
dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid);
break;
default:
break;
}
if (dst) {
unsigned long now = jiffies;
if (test_bit(BR_FDB_LOCAL, &dst->flags))
return br_pass_frame_up(skb, false);
if (now != dst->used)
dst->used = now;
br_forward(dst->dst, skb, local_rcv, false);
} else {
if (!mcast_hit)
br_flood(br, skb, pkt_type, local_rcv, false, vid);
else
br_multicast_flood(mdst, skb, brmctx, local_rcv, false);
}
if (local_rcv)
return br_pass_frame_up(skb, promisc);
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) &&
nbp_state_should_learn(p) &&
!br_opt_get(p->br, BROPT_NO_LL_LEARN) &&
br_should_learn(p, skb, &vid))
br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0);
}
/* note: already called with rcu_read_lock */
static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
{
__br_handle_local_finish(skb);
/* return 1 to signal the okfn() was called so it's ok to use the skb */
return 1;
}
static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb)
{
#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
struct nf_hook_entries *e = NULL;
struct nf_hook_state state;
unsigned int verdict, i;
struct net *net;
int ret;
net = dev_net(skb->dev);
#ifdef HAVE_JUMP_LABEL
if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING]))
goto frame_finish;
#endif
e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]);
if (!e)
goto frame_finish;
nf_hook_state_init(&state, NF_BR_PRE_ROUTING,
NFPROTO_BRIDGE, skb->dev, NULL, NULL,
net, br_handle_frame_finish);
for (i = 0; i < e->num_hook_entries; i++) {
verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state);
switch (verdict & NF_VERDICT_MASK) {
case NF_ACCEPT:
if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) {
*pskb = skb;
return RX_HANDLER_PASS;
}
break;
case NF_DROP:
kfree_skb(skb);
return RX_HANDLER_CONSUMED;
case NF_QUEUE:
ret = nf_queue(skb, &state, i, verdict);
if (ret == 1)
continue;
return RX_HANDLER_CONSUMED;
default: /* STOLEN */
return RX_HANDLER_CONSUMED;
}
}
frame_finish:
net = dev_net(skb->dev);
br_handle_frame_finish(net, NULL, skb);
#else
br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
#endif
return RX_HANDLER_CONSUMED;
}
/* Return 0 if the frame was not processed otherwise 1
* note: already called with rcu_read_lock
*/
static int br_process_frame_type(struct net_bridge_port *p,
struct sk_buff *skb)
{
struct br_frame_type *tmp;
hlist_for_each_entry_rcu(tmp, &p->br->frame_type_list, list)
if (unlikely(tmp->type == skb->protocol))
return tmp->frame_handler(p, skb);
return 0;
}
/*
* Return NULL if skb is handled
* note: already called with rcu_read_lock
*/
static 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;
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;
memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
br_tc_skb_miss_set(skb, false);
p = br_port_get_rcu(skb->dev);
if (p->flags & BR_VLAN_TUNNEL)
br_handle_ingress_vlan_tunnel(skb, p, nbp_vlan_group_rcu(p));
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
*/
fwd_mask |= p->group_fwd_mask;
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;
}
BR_INPUT_SKB_CB(skb)->promisc = false;
/* The else clause should be hit when nf_hook():
* - returns < 0 (drop/error)
* - returns = 0 (stolen/nf_queue)
* Thus return 1 from the okfn() to signal the skb is ok to pass
*/
if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
dev_net(skb->dev), NULL, skb, skb->dev, NULL,
br_handle_local_finish) == 1) {
return RX_HANDLER_PASS;
} else {
return RX_HANDLER_CONSUMED;
}
}
if (unlikely(br_process_frame_type(p, skb)))
return RX_HANDLER_PASS;
forward:
if (br_mst_is_enabled(p->br))
goto defer_stp_filtering;
switch (p->state) {
case BR_STATE_FORWARDING:
case BR_STATE_LEARNING:
defer_stp_filtering:
if (ether_addr_equal(p->br->dev->dev_addr, dest))
skb->pkt_type = PACKET_HOST;
return nf_hook_bridge_pre(skb, pskb);
default:
drop:
kfree_skb(skb);
}
return RX_HANDLER_CONSUMED;
}
/* This function has no purpose other than to appease the br_port_get_rcu/rtnl
* helpers which identify bridged ports according to the rx_handler installed
* on them (so there _needs_ to be a bridge rx_handler even if we don't need it
* to do anything useful). This bridge won't support traffic to/from the stack,
* but only hardware bridging. So return RX_HANDLER_PASS so we don't steal
* frames from the ETH_P_XDSA packet_type handler.
*/
static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb)
{
return RX_HANDLER_PASS;
}
rx_handler_func_t *br_get_rx_handler(const struct net_device *dev)
{
if (netdev_uses_dsa(dev))
return br_handle_frame_dummy;
return br_handle_frame;
}
void br_add_frame(struct net_bridge *br, struct br_frame_type *ft)
{
hlist_add_head_rcu(&ft->list, &br->frame_type_list);
}
void br_del_frame(struct net_bridge *br, struct br_frame_type *ft)
{
struct br_frame_type *tmp;
hlist_for_each_entry(tmp, &br->frame_type_list, list)
if (ft == tmp) {
hlist_del_rcu(&ft->list);
return;
}
}