Subject: Re: [PATCH net v2] ip_tunnel: Set network header properly for IP_ECN_decapsulate()

From: Sergei Shtylyov <[email-masked]>
Date: Sun, 04 May 2014 19:13:12 +0400

Hello.

On 04-05-2014 9:40, Ying Cai wrote:

> In ip_tunnel_rcv(), set skb->network_header to inner IP header
> before IP_ECN_decapsulate().

> Without the fix, IP_ECN_decapsulate() takes outer IP header as
> inner IP header, possibly causing error messages or packet drops.

> Note that this skb_reset_network_header() call was in this spot when
> the original feature for checking consistency of ECN bits through
> tunnels was added in eccc1bb8d4b4 ("tunnel: drop packet if ECN present
> with not-ECT"). It was only removed from this spot in 3d7b46cd20e3
> ("ip_tunnel: push generic protocol handling to ip_tunnel module.").

> Fixes: 3d7b46cd20e3 ("ip_tunnel: push generic protocol handling to
> ip_tunnel module.")
> Reported-by: Neal Cardwell <[email-masked]>
> Signed-off-by: Ying Cai <[email-masked]>
> Acked-by: Neal Cardwell <[email-masked]>
> ---
>   net/ipv4/ip_tunnel.c | 2 ++
>   1 file changed, 2 insertions(+)

> diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
> index fa5b751..b3f8597 100644
> --- a/net/ipv4/ip_tunnel.c
> +++ b/net/ipv4/ip_tunnel.c
> @@ -442,6 +442,8 @@ int ip_tunnel_rcv(struct ip_tunnel *tunnel, struct
> sk_buff *skb,
>    tunnel->i_seqno = ntohl(tpi->seq) + 1;
>    }
>
> + skb_reset_network_header(skb);
> +
>    err = IP_ECN_decapsulate(iph, skb);
>    if (unlikely(err)) {
>    if (log_ecn_error)

    The path is seriously whitespace-damaged. See 
Documentation/email-clients.txt in the kernel tree.

WBR, Sergei