91d2c34a4e
There are multiple problems with the newly added netpoll support: 1) Use-after-free on each netpoll packet. 2) Invoking unsafe code on netpoll/IRQ path. 3) Breaks when netpoll is enabled on the underlying device. This patch fixes all of these problems. In particular, we now allocate proper netpoll structures for each underlying device. We only allow netpoll to be enabled on the bridge when all the devices underneath it support netpoll. Once it is enabled, we do not allow non-netpoll devices to join the bridge (until netpoll is disabled again). This allows us to do away with the npinfo juggling that caused problem number 1. Incidentally this patch fixes number 2 by bypassing unsafe code such as multicast snooping and netfilter. Reported-by: Qianfeng Zhang <frzhang@redhat.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
275 lines
6.1 KiB
C
275 lines
6.1 KiB
C
/*
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* Forwarding decision
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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/err.h>
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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/netpoll.h>
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#include <linux/skbuff.h>
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#include <linux/if_vlan.h>
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#include <linux/netfilter_bridge.h>
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#include "br_private.h"
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static int deliver_clone(const struct net_bridge_port *prev,
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struct sk_buff *skb,
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void (*__packet_hook)(const struct net_bridge_port *p,
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struct sk_buff *skb));
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/* Don't forward packets to originating port or forwarding diasabled */
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static inline int should_deliver(const struct net_bridge_port *p,
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const struct sk_buff *skb)
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{
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return (((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
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p->state == BR_STATE_FORWARDING);
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}
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static inline unsigned packet_length(const struct sk_buff *skb)
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{
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return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
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}
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int br_dev_queue_push_xmit(struct sk_buff *skb)
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{
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/* drop mtu oversized packets except gso */
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if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
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kfree_skb(skb);
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else {
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/* ip_fragment doesn't copy the MAC header */
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if (nf_bridge_maybe_copy_header(skb))
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kfree_skb(skb);
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else {
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skb_push(skb, ETH_HLEN);
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dev_queue_xmit(skb);
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}
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}
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return 0;
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}
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int br_forward_finish(struct sk_buff *skb)
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{
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return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
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br_dev_queue_push_xmit);
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}
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static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
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{
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skb->dev = to->dev;
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if (unlikely(netpoll_tx_running(to->dev))) {
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if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
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kfree_skb(skb);
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else {
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skb_push(skb, ETH_HLEN);
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br_netpoll_send_skb(to, skb);
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}
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return;
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}
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NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
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br_forward_finish);
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}
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static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
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{
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struct net_device *indev;
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if (skb_warn_if_lro(skb)) {
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kfree_skb(skb);
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return;
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}
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indev = skb->dev;
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skb->dev = to->dev;
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skb_forward_csum(skb);
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NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
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br_forward_finish);
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}
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/* called with rcu_read_lock */
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void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
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{
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if (should_deliver(to, skb)) {
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__br_deliver(to, skb);
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return;
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}
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kfree_skb(skb);
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}
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/* called with rcu_read_lock */
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void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
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{
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if (should_deliver(to, skb)) {
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if (skb0)
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deliver_clone(to, skb, __br_forward);
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else
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__br_forward(to, skb);
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return;
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}
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if (!skb0)
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kfree_skb(skb);
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}
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static int deliver_clone(const struct net_bridge_port *prev,
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struct sk_buff *skb,
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void (*__packet_hook)(const struct net_bridge_port *p,
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struct sk_buff *skb))
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{
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skb = skb_clone(skb, GFP_ATOMIC);
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if (!skb) {
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struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
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dev->stats.tx_dropped++;
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return -ENOMEM;
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}
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__packet_hook(prev, skb);
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return 0;
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}
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static struct net_bridge_port *maybe_deliver(
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struct net_bridge_port *prev, struct net_bridge_port *p,
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struct sk_buff *skb,
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void (*__packet_hook)(const struct net_bridge_port *p,
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struct sk_buff *skb))
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{
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int err;
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if (!should_deliver(p, skb))
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return prev;
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if (!prev)
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goto out;
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err = deliver_clone(prev, skb, __packet_hook);
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if (err)
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return ERR_PTR(err);
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out:
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return p;
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}
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/* called under bridge lock */
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static void br_flood(struct net_bridge *br, struct sk_buff *skb,
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struct sk_buff *skb0,
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void (*__packet_hook)(const struct net_bridge_port *p,
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struct sk_buff *skb))
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{
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struct net_bridge_port *p;
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struct net_bridge_port *prev;
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prev = NULL;
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list_for_each_entry_rcu(p, &br->port_list, list) {
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prev = maybe_deliver(prev, p, skb, __packet_hook);
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if (IS_ERR(prev))
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goto out;
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}
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if (!prev)
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goto out;
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if (skb0)
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deliver_clone(prev, skb, __packet_hook);
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else
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__packet_hook(prev, skb);
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return;
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out:
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if (!skb0)
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kfree_skb(skb);
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}
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/* called with rcu_read_lock */
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void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb)
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{
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br_flood(br, skb, NULL, __br_deliver);
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}
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/* called under bridge lock */
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void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
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struct sk_buff *skb2)
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{
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br_flood(br, skb, skb2, __br_forward);
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}
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#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
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/* called with rcu_read_lock */
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static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
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struct sk_buff *skb, struct sk_buff *skb0,
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void (*__packet_hook)(
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const struct net_bridge_port *p,
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struct sk_buff *skb))
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{
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struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
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struct net_bridge *br = netdev_priv(dev);
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struct net_bridge_port *prev = NULL;
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struct net_bridge_port_group *p;
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struct hlist_node *rp;
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rp = rcu_dereference(br->router_list.first);
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p = mdst ? rcu_dereference(mdst->ports) : NULL;
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while (p || rp) {
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struct net_bridge_port *port, *lport, *rport;
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lport = p ? p->port : NULL;
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rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
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NULL;
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port = (unsigned long)lport > (unsigned long)rport ?
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lport : rport;
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prev = maybe_deliver(prev, port, skb, __packet_hook);
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if (IS_ERR(prev))
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goto out;
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if ((unsigned long)lport >= (unsigned long)port)
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p = rcu_dereference(p->next);
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if ((unsigned long)rport >= (unsigned long)port)
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rp = rcu_dereference(rp->next);
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}
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if (!prev)
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goto out;
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if (skb0)
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deliver_clone(prev, skb, __packet_hook);
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else
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__packet_hook(prev, skb);
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return;
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out:
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if (!skb0)
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kfree_skb(skb);
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}
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/* called with rcu_read_lock */
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void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
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struct sk_buff *skb)
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{
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br_multicast_flood(mdst, skb, NULL, __br_deliver);
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}
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/* called with rcu_read_lock */
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void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
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struct sk_buff *skb, struct sk_buff *skb2)
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{
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br_multicast_flood(mdst, skb, skb2, __br_forward);
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}
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#endif
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