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| author | Alexandre Knecht <knecht.alexandre@gmail.com> | 2025-12-28 03:00:57 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-01-17 16:29:58 +0100 |
| commit | 4c8facf028ec7ef8a3a70da2039189322e6250cb (patch) | |
| tree | c390d5bc07e441b97469cc917719b65b5e620937 | |
| parent | 94e070cd50790317fba7787ae6006934b7edcb6f (diff) | |
bridge: fix C-VLAN preservation in 802.1ad vlan_tunnel egress
[ Upstream commit 3128df6be147768fe536986fbb85db1d37806a9f ]
When using an 802.1ad bridge with vlan_tunnel, the C-VLAN tag is
incorrectly stripped from frames during egress processing.
br_handle_egress_vlan_tunnel() uses skb_vlan_pop() to remove the S-VLAN
from hwaccel before VXLAN encapsulation. However, skb_vlan_pop() also
moves any "next" VLAN from the payload into hwaccel:
/* move next vlan tag to hw accel tag */
__skb_vlan_pop(skb, &vlan_tci);
__vlan_hwaccel_put_tag(skb, vlan_proto, vlan_tci);
For QinQ frames where the C-VLAN sits in the payload, this moves it to
hwaccel where it gets lost during VXLAN encapsulation.
Fix by calling __vlan_hwaccel_clear_tag() directly, which clears only
the hwaccel S-VLAN and leaves the payload untouched.
This path is only taken when vlan_tunnel is enabled and tunnel_info
is configured, so 802.1Q bridges are unaffected.
Tested with 802.1ad bridge + VXLAN vlan_tunnel, verified C-VLAN
preserved in VXLAN payload via tcpdump.
Fixes: 11538d039ac6 ("bridge: vlan dst_metadata hooks in ingress and egress paths")
Signed-off-by: Alexandre Knecht <knecht.alexandre@gmail.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/20251228020057.2788865-1-knecht.alexandre@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | net/bridge/br_vlan_tunnel.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/net/bridge/br_vlan_tunnel.c b/net/bridge/br_vlan_tunnel.c index 81833ca7a2c7..b41494ce5943 100644 --- a/net/bridge/br_vlan_tunnel.c +++ b/net/bridge/br_vlan_tunnel.c @@ -187,7 +187,6 @@ int br_handle_egress_vlan_tunnel(struct sk_buff *skb, { struct metadata_dst *tunnel_dst; __be64 tunnel_id; - int err; if (!vlan) return 0; @@ -197,9 +196,13 @@ int br_handle_egress_vlan_tunnel(struct sk_buff *skb, return 0; skb_dst_drop(skb); - err = skb_vlan_pop(skb); - if (err) - return err; + /* For 802.1ad (QinQ), skb_vlan_pop() incorrectly moves the C-VLAN + * from payload to hwaccel after clearing S-VLAN. We only need to + * clear the hwaccel S-VLAN; the C-VLAN must stay in payload for + * correct VXLAN encapsulation. This is also correct for 802.1Q + * where no C-VLAN exists in payload. + */ + __vlan_hwaccel_clear_tag(skb); if (BR_INPUT_SKB_CB(skb)->backup_nhid) { tunnel_dst = __ip_tun_set_dst(0, 0, 0, 0, 0, TUNNEL_KEY, |