linux-kernel - [RFC net-next (resend) 1/4] net: bridge: respect sticky flag on external learn

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Message-ID: <20241108035546.2055996-2-elliot.ayrey@alliedtelesis.co.nz>
Date: Fri,  8 Nov 2024 16:55:43 +1300
From: Elliot Ayrey <elliot.ayrey@...iedtelesis.co.nz>
To: "David S . Miller" <davem@...emloft.net>,
	Andrew Lunn <andrew@...n.ch>,
	Florian Fainelli <f.fainelli@...il.com>,
	Vladimir Oltean <olteanv@...il.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Roopa Prabhu <roopa@...dia.com>,
	Nikolay Aleksandrov <razor@...ckwall.org>,
	Simon Horman <horms@...nel.org>
Cc: netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	bridge@...ts.linux.dev,
	Elliot Ayrey <elliot.ayrey@...iedtelesis.co.nz>
Subject: [RFC net-next (resend) 1/4] net: bridge: respect sticky flag on external learn

The fdb sticky flag is used to stop a host from roaming to another
port. However upon receiving a switchdev notification to update an fdb
entry the sticky flag is not respected and as long as the new entry is
not locked the host will be allowed to roam to the new port.

Fix this by considering the sticky flag before allowing an externally
learned host to roam.

Signed-off-by: Elliot Ayrey <elliot.ayrey@...iedtelesis.co.nz>
---
 net/bridge/br_fdb.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index 1cd7bade9b3b..72663ca824d3 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -1457,7 +1457,8 @@ int br_fdb_external_learn_add(struct net_bridge *br, struct net_bridge_port *p,
 
 		fdb->updated = jiffies;
 
-		if (READ_ONCE(fdb->dst) != p) {
+		if (READ_ONCE(fdb->dst) != p &&
+		    !test_bit(BR_FDB_STICKY, &fdb->flags)) {
 			WRITE_ONCE(fdb->dst, p);
 			modified = true;
 		}