| From 22e274e239e0251dd02f67017bcb1119a1eb2d14 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Wed, 19 May 2021 15:47:42 +0000 |
| Subject: bpf: Set mac_len in bpf_skb_change_head |
| |
| 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 9323d34d34cc..52f4359efbd2 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; |
| -- |
| 2.30.2 |
| |
