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authorNikolay Aleksandrov <nikolay@cumulusnetworks.com>2019-04-11 13:56:39 +0300
committerDavid S. Miller <davem@davemloft.net>2019-04-16 20:30:40 -0700
commit3b2e2904deb314cc77a2192f506f2fd44e3d10d0 (patch)
treea81ef54cc6e58bd40064722566af5c1eb85da69b
parent614c70f35cd77a9af8e2ca841dcdb121cec3068f (diff)
downloadlinux-3b2e2904deb314cc77a2192f506f2fd44e3d10d0.tar.bz2
net: bridge: fix per-port af_packet sockets
When the commit below was introduced it changed two visible things: - the skb was no longer passed through the protocol handlers with the original device - the skb was passed up the stack with skb->dev = bridge The first change broke af_packet sockets on bridge ports. For example we use them for hostapd which listens for ETH_P_PAE packets on the ports. We discussed two possible fixes: - create a clone and pass it through NF_HOOK(), act on the original skb based on the result - somehow signal to the caller from the okfn() that it was called, meaning the skb is ok to be passed, which this patch is trying to implement via returning 1 from the bridge link-local okfn() Note that we rely on the fact that NF_QUEUE/STOLEN would return 0 and drop/error would return < 0 thus the okfn() is called only when the return was 1, so we signal to the caller that it was called by preserving the return value from nf_hook(). Fixes: 8626c56c8279 ("bridge: fix potential use-after-free when hook returns QUEUE or STOLEN verdict") Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/bridge/br_input.c23
1 files changed, 14 insertions, 9 deletions
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 5ea7e56119c1..ba303ee99b9b 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -197,13 +197,10 @@ static void __br_handle_local_finish(struct sk_buff *skb)
/* 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 1 to signal the okfn() was called so it's ok to use the skb */
+ return 1;
}
/*
@@ -280,10 +277,18 @@ rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
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;
+ /* 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;
+ }
}
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