From: Martin Willi <martin@strongswan.org>
Date: Mon, 19 Apr 2021 16:15:59 +0200
Subject: net, xdp: Update pkt_type if generic XDP changes unicast MAC
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Patch-mainline: v5.13-rc1
Git-commit: 22b6034323fd736f260e00b9ea85c634abeb3446
References: git-fixes
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
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
net/core/dev.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4472,9 +4472,9 @@ static u32 netif_receive_generic_xdp(str
struct netdev_rx_queue *rxqueue;
void *orig_data, *orig_data_end;
u32 metalen, act = XDP_DROP;
+ bool orig_bcast, orig_host;
__be16 orig_eth_type;
struct ethhdr *eth;
- bool orig_bcast;
int hlen, off;
u32 mac_len;
@@ -4516,6 +4516,7 @@ static u32 netif_receive_generic_xdp(str
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;
@@ -4549,8 +4550,11 @@ static u32 netif_receive_generic_xdp(str
/* 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);
}