Patch "bridge: Fix incorrect re-injection of LLDP packets" has been added to the 4.6-stable tree

This is a note to let you know that I've just added the patch titled

bridge: Fix incorrect re-injection of LLDP packets

to the 4.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
bridge-fix-incorrect-re-injection-of-lldp-packets.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ido Schimmel <[email protected]>
Date: Fri, 22 Jul 2016 14:56:20 +0300
Subject: bridge: Fix incorrect re-injection of LLDP packets

From: Ido Schimmel <[email protected]>

[ Upstream commit baedbe55884c003819f5c8c063ec3d2569414296 ]

Commit 8626c56c8279 ("bridge: fix potential use-after-free when hook returns QUEUE or STOLEN verdict") caused LLDP packets arriving through a bridge port to be re-injected to the Rx path with skb->dev set to the bridge device, but this breaks the lldpad daemon.

The lldpad daemon opens a packet socket with protocol set to ETH_P_LLDP for any valid device on the system, which doesn't not include soft devices such as bridge and VLAN.

Since packet sockets (ptype_base) are processed in the Rx path after the Rx handler, LLDP packets with skb->dev set to the bridge device never reach the lldpad daemon.

Fix this by making the bridge's Rx handler re-inject LLDP packets with RX_HANDLER_PASS, which effectively restores the behaviour prior to the mentioned commit.

This means netfilter will never receive LLDP packets coming through a bridge port, as I don't see a way in which we can have okfn() consume the packet without breaking existing behaviour. I've already carried out a similar fix for STP packets in commit 56fae404fb2c ("bridge: Fix incorrect re-injection of STP packets").

---
 net/bridge/br_input.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

@@ -213,6 +213,16 @@ drop:
 }
 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)
 {

@@ -279,6 +289,14 @@ rx_handler_result_t br_handle_frame(stru
 		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;

Patches currently in stable-queue which might be from [email protected] are

queue-4.6/bridge-fix-incorrect-re-injection-of-lldp-packets.patch