[PATCH 4.19 040/120] net: bridge: sync fdb to new unicast-filtering ports

Greg Kroah-Hartman
2021-07-26T16:01:06Z

From: Wolfgang Bumiller <w.bumiller@proxmox.com>

commit a019abd8022061b917da767cd1a66ed823724eab upstream.

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>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/bridge/br_if.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)

--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -564,7 +564,7 @@ int br_add_if(struct net_bridge *br, str
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, or DSA-enabled
* master network devices since the bridge layer rx_handler prevents
@@ -640,6 +640,19 @@ int br_add_if(struct net_bridge *br, str
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);

@@ -680,6 +693,8 @@ int br_add_if(struct net_bridge *br, str
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);