From: Jussi Maki joamaki@gmail.com
[ Upstream commit 84316ca4e100d8cbfccd9f774e23817cb2059868 ]
The skb_change_head() helper did not set "skb->mac_len", which is problematic when it's used in combination with skb_redirect_peer(). Without it, redirecting a packet from a L3 device such as wireguard to the veth peer device will cause skb->data to point to the middle of the IP header on entry to tcp_v4_rcv() since the L2 header is not pulled correctly due to mac_len=0.
Fixes: 3a0af8fd61f9 ("bpf: BPF for lightweight tunnel infrastructure") Signed-off-by: Jussi Maki joamaki@gmail.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Link: https://lore.kernel.org/bpf/20210519154743.2554771-2-joamaki@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/filter.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/net/core/filter.c b/net/core/filter.c index 9358bc4a3711..ef6bdbb63ecb 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3782,6 +3782,7 @@ static inline int __bpf_skb_change_head(struct sk_buff *skb, u32 head_room, __skb_push(skb, head_room); memset(skb->data, 0, head_room); skb_reset_mac_header(skb); + skb_reset_mac_len(skb); }
return ret;