bridge: Fix incorrect re-injection of LLDP packets

[ 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").

Fixes: 8626c56c8279 ("bridge: fix potential use-after-free when hook returns QUEUE or STOLEN verdict")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Cc: Florian Westphal <fw@strlen.de>
Cc: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 16079772222860977264133fa49bb0cf33b9b0d5..b32f5a4750bf7ef33cfed971386d3c62cf8acf3f 100644 (file)
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -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(struct sk_buff **pskb)
                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;