From: Martin Willi martin@strongswan.org
[ Upstream commit 22b6034323fd736f260e00b9ea85c634abeb3446 ]
If a generic XDP program changes the destination MAC address from/to multicast/broadcast, the skb->pkt_type is updated to properly handle the packet when passed up the stack. When changing the MAC from/to the NICs MAC, PACKET_HOST/OTHERHOST is not updated, though, making the behavior different from that of native XDP.
Remember the PACKET_HOST/OTHERHOST state before calling the program in generic XDP, and update pkt_type accordingly if the destination MAC address has changed. As eth_type_trans() assumes a default pkt_type of PACKET_HOST, restore that before calling it.
The use case for this is when a XDP program wants to push received packets up the stack by rewriting the MAC to the NICs MAC, for example by cluster nodes sharing MAC addresses.
Fixes: 297249569932 ("net: fix generic XDP to handle if eth header was mangled") Signed-off-by: Martin Willi martin@strongswan.org Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Toke Høiland-Jørgensen toke@redhat.com Link: https://lore.kernel.org/bpf/20210419141559.8611-1-martin@strongswan.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/dev.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/net/core/dev.c b/net/core/dev.c index 15fe36332fb8..70829c568645 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4672,10 +4672,10 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, void *orig_data, *orig_data_end, *hard_start; struct netdev_rx_queue *rxqueue; u32 metalen, act = XDP_DROP; + bool orig_bcast, orig_host; u32 mac_len, frame_sz; __be16 orig_eth_type; struct ethhdr *eth; - bool orig_bcast; int off;
/* Reinjected packets coming from act_mirred or similar should @@ -4722,6 +4722,7 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, orig_data_end = xdp->data_end; orig_data = xdp->data; eth = (struct ethhdr *)xdp->data; + orig_host = ether_addr_equal_64bits(eth->h_dest, skb->dev->dev_addr); orig_bcast = is_multicast_ether_addr_64bits(eth->h_dest); orig_eth_type = eth->h_proto;
@@ -4749,8 +4750,11 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, /* check if XDP changed eth hdr such SKB needs update */ eth = (struct ethhdr *)xdp->data; if ((orig_eth_type != eth->h_proto) || + (orig_host != ether_addr_equal_64bits(eth->h_dest, + skb->dev->dev_addr)) || (orig_bcast != is_multicast_ether_addr_64bits(eth->h_dest))) { __skb_push(skb, ETH_HLEN); + skb->pkt_type = PACKET_HOST; skb->protocol = eth_type_trans(skb, skb->dev); }