netdev - Re: [PATCH bpf v2] bpf: clear skb->tstamp in bpf

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Date:   Fri, 13 Dec 2019 13:09:12 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Lorenz Bauer <lmb@...udflare.com>, ast@...nel.org,
        daniel@...earbox.net, davem@...emloft.net,
        Eric Dumazet <edumazet@...gle.com>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     kernel-team@...udflare.com
Subject: Re: [PATCH bpf v2] bpf: clear skb->tstamp in bpf_redirect when
 necessary



On 12/13/19 10:08 AM, Lorenz Bauer wrote:
> Redirecting a packet from ingress to egress by using bpf_redirect
> breaks if the egress interface has an fq qdisc installed. This is the same
> problem as fixed in 'commit 8203e2d844d3 ("net: clear skb->tstamp in forwarding paths")
> 
> Clear skb->tstamp when redirecting into the egress path.
> 
> Fixes: 80b14dee2bea ("net: Add a new socket option for a future transmit time.")
> Fixes: fb420d5d91c1 ("tcp/fq: move back to CLOCK_MONOTONIC")
> Signed-off-by: Lorenz Bauer <lmb@...udflare.com>
> ---
>  net/core/filter.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/net/core/filter.c b/net/core/filter.c
> index f1e703eed3d2..d914257763b5 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -2055,6 +2055,7 @@ static inline int __bpf_tx_skb(struct net_device *dev, struct sk_buff *skb)
>  	}
>  
>  	skb->dev = dev;
> +	skb->tstamp = 0;
>  
>  	dev_xmit_recursion_inc();
>  	ret = dev_queue_xmit(skb);
> 

Thanks !

Reviewed-by: Eric Dumazet <edumazet@...gle.com>