net: bridge: BROPT_FDB_LOCAL_VLAN_0: Look up FDB on VLAN 0 on miss

When BROPT_FDB_LOCAL_VLAN_0 is enabled, the local FDB entries for the
member ports as well as the bridge itself should not be created per-VLAN,
but instead only on VLAN 0.

That means that br_handle_frame_finish() needs to make two lookups: the
primary lookup on an appropriate VLAN, and when that misses, a lookup on
VLAN 0.

Have the second lookup only accept local MAC addresses. Turning this into a
generic second-lookup feature is not the goal.

Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/8087475009dce360fb68d873b1ed9c80827da302.1757004393.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 5f6ac9bf15275da6a4ec69eb44a971b87cb767b7..67b4c905e49a2135b0b8ab04304490e5a26b8719 100644 (file)
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -202,6 +202,14 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
                break;
        case BR_PKT_UNICAST:
                dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid);
+               if (unlikely(!dst && vid &&
+                            br_opt_get(br, BROPT_FDB_LOCAL_VLAN_0))) {
+                       dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, 0);
+                       if (dst &&
+                           (!test_bit(BR_FDB_LOCAL, &dst->flags) ||
+                            test_bit(BR_FDB_ADDED_BY_USER, &dst->flags)))
+                               dst = NULL;
+               }
                break;
        default:
                break;