mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-09 14:56:40 +07:00
8626c56c82
Zefir Kurtisi reported kernel panic with an openwrt specific patch. However, it turns out that mainline has a similar bug waiting to happen. Once NF_HOOK() returns the skb is in undefined state and must not be used. Moreover, the okfn must consume the skb to support async processing (NF_QUEUE). Current okfn in this spot doesn't consume it and caller assumes that NF_HOOK return value tells us if skb was freed or not, but thats wrong. It "works" because no in-tree user registers a NFPROTO_BRIDGE hook at LOCAL_IN that returns STOLEN or NF_QUEUE verdicts. Once we add NF_QUEUE support for nftables bridge this will break -- NF_QUEUE holds the skb for async processing, caller will erronoulsy return RX_HANDLER_PASS and on reinject netfilter will access free'd skb. Fix this by pushing skb up the stack in the okfn instead. NB: It also seems dubious to use LOCAL_IN while bypassing PRE_ROUTING completely in this case but this is how its been forever so it seems preferable to not change this. Cc: Felix Fietkau <nbd@openwrt.org> Cc: Zefir Kurtisi <zefir.kurtisi@neratec.com> Signed-off-by: Florian Westphal <fw@strlen.de> Tested-by: Zefir Kurtisi <zefir.kurtisi@neratec.com> Signed-off-by: David S. Miller <davem@davemloft.net>
321 lines
7.8 KiB
C
321 lines
7.8 KiB
C
/*
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* Handle incoming frames
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* Linux ethernet bridge
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*
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* Authors:
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* Lennert Buytenhek <buytenh@gnu.org>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/slab.h>
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#include <linux/kernel.h>
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#include <linux/netdevice.h>
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#include <linux/etherdevice.h>
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#include <linux/netfilter_bridge.h>
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#include <linux/neighbour.h>
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#include <net/arp.h>
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#include <linux/export.h>
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#include <linux/rculist.h>
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#include "br_private.h"
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/* Hook for brouter */
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br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
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EXPORT_SYMBOL(br_should_route_hook);
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static int
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br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
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{
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return netif_receive_skb(skb);
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}
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static int br_pass_frame_up(struct sk_buff *skb)
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{
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struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
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struct net_bridge *br = netdev_priv(brdev);
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struct net_bridge_vlan_group *vg;
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struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
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u64_stats_update_begin(&brstats->syncp);
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brstats->rx_packets++;
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brstats->rx_bytes += skb->len;
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u64_stats_update_end(&brstats->syncp);
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vg = br_vlan_group_rcu(br);
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/* Bridge is just like any other port. Make sure the
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* packet is allowed except in promisc modue when someone
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* may be running packet capture.
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*/
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if (!(brdev->flags & IFF_PROMISC) &&
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!br_allowed_egress(vg, skb)) {
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kfree_skb(skb);
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return NET_RX_DROP;
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}
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indev = skb->dev;
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skb->dev = brdev;
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skb = br_handle_vlan(br, vg, skb);
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if (!skb)
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return NET_RX_DROP;
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return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
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dev_net(indev), NULL, skb, indev, NULL,
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br_netif_receive_skb);
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}
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static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br,
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u16 vid, struct net_bridge_port *p)
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{
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struct net_device *dev = br->dev;
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struct neighbour *n;
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struct arphdr *parp;
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u8 *arpptr, *sha;
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__be32 sip, tip;
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BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
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if (dev->flags & IFF_NOARP)
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return;
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if (!pskb_may_pull(skb, arp_hdr_len(dev))) {
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dev->stats.tx_dropped++;
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return;
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}
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parp = arp_hdr(skb);
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if (parp->ar_pro != htons(ETH_P_IP) ||
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parp->ar_op != htons(ARPOP_REQUEST) ||
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parp->ar_hln != dev->addr_len ||
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parp->ar_pln != 4)
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return;
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arpptr = (u8 *)parp + sizeof(struct arphdr);
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sha = arpptr;
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arpptr += dev->addr_len; /* sha */
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memcpy(&sip, arpptr, sizeof(sip));
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arpptr += sizeof(sip);
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arpptr += dev->addr_len; /* tha */
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memcpy(&tip, arpptr, sizeof(tip));
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if (ipv4_is_loopback(tip) ||
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ipv4_is_multicast(tip))
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return;
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n = neigh_lookup(&arp_tbl, &tip, dev);
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if (n) {
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struct net_bridge_fdb_entry *f;
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if (!(n->nud_state & NUD_VALID)) {
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neigh_release(n);
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return;
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}
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f = __br_fdb_get(br, n->ha, vid);
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if (f && ((p->flags & BR_PROXYARP) ||
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(f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) {
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arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip,
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sha, n->ha, sha);
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BR_INPUT_SKB_CB(skb)->proxyarp_replied = true;
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}
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neigh_release(n);
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}
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}
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/* note: already called with rcu_read_lock */
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int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
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{
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const unsigned char *dest = eth_hdr(skb)->h_dest;
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struct net_bridge_port *p = br_port_get_rcu(skb->dev);
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struct net_bridge *br;
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struct net_bridge_fdb_entry *dst;
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struct net_bridge_mdb_entry *mdst;
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struct sk_buff *skb2;
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bool unicast = true;
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u16 vid = 0;
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if (!p || p->state == BR_STATE_DISABLED)
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goto drop;
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if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid))
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goto out;
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/* insert into forwarding database after filtering to avoid spoofing */
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br = p->br;
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if (p->flags & BR_LEARNING)
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br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false);
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if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&
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br_multicast_rcv(br, p, skb, vid))
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goto drop;
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if (p->state == BR_STATE_LEARNING)
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goto drop;
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BR_INPUT_SKB_CB(skb)->brdev = br->dev;
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/* The packet skb2 goes to the local host (NULL to skip). */
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skb2 = NULL;
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if (br->dev->flags & IFF_PROMISC)
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skb2 = skb;
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dst = NULL;
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if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP))
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br_do_proxy_arp(skb, br, vid, p);
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if (is_broadcast_ether_addr(dest)) {
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skb2 = skb;
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unicast = false;
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} else if (is_multicast_ether_addr(dest)) {
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mdst = br_mdb_get(br, skb, vid);
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if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
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br_multicast_querier_exists(br, eth_hdr(skb))) {
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if ((mdst && mdst->mglist) ||
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br_multicast_is_router(br))
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skb2 = skb;
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br_multicast_forward(mdst, skb, skb2);
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skb = NULL;
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if (!skb2)
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goto out;
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} else
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skb2 = skb;
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unicast = false;
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br->dev->stats.multicast++;
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} else if ((dst = __br_fdb_get(br, dest, vid)) &&
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dst->is_local) {
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skb2 = skb;
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/* Do not forward the packet since it's local. */
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skb = NULL;
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}
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if (skb) {
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if (dst) {
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dst->used = jiffies;
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br_forward(dst->dst, skb, skb2);
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} else
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br_flood_forward(br, skb, skb2, unicast);
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}
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if (skb2)
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return br_pass_frame_up(skb2);
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out:
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return 0;
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drop:
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kfree_skb(skb);
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goto out;
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}
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EXPORT_SYMBOL_GPL(br_handle_frame_finish);
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/* note: already called with rcu_read_lock */
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static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
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{
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struct net_bridge_port *p = br_port_get_rcu(skb->dev);
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u16 vid = 0;
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/* check if vlan is allowed, to avoid spoofing */
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if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid))
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br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false);
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BR_INPUT_SKB_CB(skb)->brdev = p->br->dev;
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br_pass_frame_up(skb);
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return 0;
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}
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/*
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* Return NULL if skb is handled
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* note: already called with rcu_read_lock
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*/
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rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
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{
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struct net_bridge_port *p;
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struct sk_buff *skb = *pskb;
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const unsigned char *dest = eth_hdr(skb)->h_dest;
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br_should_route_hook_t *rhook;
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if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
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return RX_HANDLER_PASS;
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if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
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goto drop;
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skb = skb_share_check(skb, GFP_ATOMIC);
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if (!skb)
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return RX_HANDLER_CONSUMED;
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p = br_port_get_rcu(skb->dev);
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if (unlikely(is_link_local_ether_addr(dest))) {
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u16 fwd_mask = p->br->group_fwd_mask_required;
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/*
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* See IEEE 802.1D Table 7-10 Reserved addresses
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*
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* Assignment Value
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* Bridge Group Address 01-80-C2-00-00-00
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* (MAC Control) 802.3 01-80-C2-00-00-01
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* (Link Aggregation) 802.3 01-80-C2-00-00-02
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* 802.1X PAE address 01-80-C2-00-00-03
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*
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* 802.1AB LLDP 01-80-C2-00-00-0E
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*
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* Others reserved for future standardization
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*/
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switch (dest[5]) {
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case 0x00: /* Bridge Group Address */
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/* If STP is turned off,
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then must forward to keep loop detection */
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if (p->br->stp_enabled == BR_NO_STP ||
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fwd_mask & (1u << dest[5]))
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goto forward;
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break;
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case 0x01: /* IEEE MAC (Pause) */
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goto drop;
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default:
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/* Allow selective forwarding for most other protocols */
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fwd_mask |= p->br->group_fwd_mask;
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if (fwd_mask & (1u << dest[5]))
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goto forward;
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}
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/* Deliver packet to local host only */
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NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev),
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NULL, skb, skb->dev, NULL, br_handle_local_finish);
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return RX_HANDLER_CONSUMED;
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}
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forward:
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switch (p->state) {
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case BR_STATE_FORWARDING:
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rhook = rcu_dereference(br_should_route_hook);
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if (rhook) {
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if ((*rhook)(skb)) {
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*pskb = skb;
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return RX_HANDLER_PASS;
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}
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dest = eth_hdr(skb)->h_dest;
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}
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/* fall through */
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case BR_STATE_LEARNING:
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if (ether_addr_equal(p->br->dev->dev_addr, dest))
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skb->pkt_type = PACKET_HOST;
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NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING,
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dev_net(skb->dev), NULL, skb, skb->dev, NULL,
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br_handle_frame_finish);
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break;
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default:
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drop:
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kfree_skb(skb);
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}
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return RX_HANDLER_CONSUMED;
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}
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