net: bridge: sync fdb to new unicast-filtering ports

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

patches/kernel/0006-net-bridge-sync-fdb-to-new-unicast-filtering-ports.patch

@@ -0,0 +1,68 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Wolfgang Bumiller <w.bumiller@proxmox.com>
+Date: Fri, 2 Jul 2021 14:07:36 +0200
+Subject: [PATCH] net: bridge: sync fdb to new unicast-filtering ports
+
+Since commit 2796d0c648c9 ("bridge: Automatically manage
+port promiscuous mode.")
+bridges with `vlan_filtering 1` and only 1 auto-port don't
+set IFF_PROMISC for unicast-filtering-capable ports.
+
+Normally on port changes `br_manage_promisc` is called to
+update the promisc flags and unicast filters if necessary,
+but it cannot distinguish between *new* ports and ones
+losing their promisc flag, and new ports end up not
+receiving the MAC address list.
+
+Fix this by calling `br_fdb_sync_static` in `br_add_if`
+after the port promisc flags are updated and the unicast
+filter was supposed to have been filled.
+
+Fixes: 2796d0c648c9 ("bridge: Automatically manage port promiscuous mode.")
+Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
+---
+ net/bridge/br_if.c | 17 ++++++++++++++++-
+ 1 file changed, 16 insertions(+), 1 deletion(-)
+
+diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
+index f7d2f472ae24..6e4a32354a13 100644
+--- a/net/bridge/br_if.c
++++ b/net/bridge/br_if.c
+@@ -562,7 +562,7 @@ int br_add_if(struct net_bridge *br, struct net_device *dev,
+ 	struct net_bridge_port *p;
+ 	int err = 0;
+ 	unsigned br_hr, dev_hr;
+-	bool changed_addr;
++	bool changed_addr, fdb_synced = false;
+ 
+ 	/* Don't allow bridging non-ethernet like devices. */
+ 	if ((dev->flags & IFF_LOOPBACK) ||
+@@ -652,6 +652,19 @@ int br_add_if(struct net_bridge *br, struct net_device *dev,
+ 	list_add_rcu(&p->list, &br->port_list);
+ 
+ 	nbp_update_port_count(br);
++	if (!br_promisc_port(p) && (p->dev->priv_flags & IFF_UNICAST_FLT)) {
++		/* When updating the port count we also update all ports'
++		 * promiscuous mode.
++		 * A port leaving promiscuous mode normally gets the bridge's
++		 * fdb synced to the unicast filter (if supported), however,
++		 * `br_port_clear_promisc` does not distinguish between
++		 * non-promiscuous ports and *new* ports, so we need to
++		 * sync explicitly here.
++		 */
++		fdb_synced = br_fdb_sync_static(br, p) == 0;
++		if (!fdb_synced)
++			netdev_err(dev, "failed to sync bridge static fdb addresses to this port\n");
++	}
+ 
+ 	netdev_update_features(br->dev);
+ 
+@@ -701,6 +714,8 @@ int br_add_if(struct net_bridge *br, struct net_device *dev,
+ 	return 0;
+ 
+ err7:
++	if (fdb_synced)
++		br_fdb_unsync_static(br, p);
+ 	list_del_rcu(&p->list);
+ 	br_fdb_delete_by_port(br, p, 0, 1);
+ 	nbp_update_port_count(br);