From: Florian Westphal <fw@strlen.de>
To: Changliang Wu <changliang.wu@smartx.com>
Cc: davem@davemloft.net, kuba@kernel.org, yoshfuji@linux-ipv6.org,
dsahern@kernel.org, edumazet@google.com, idosch@OSS.NVIDIA.COM,
amcohen@nvidia.com, fw@strlen.de, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ipv4: add sysctl knob to control the discarding of skb from local in ip_forward
Date: Tue, 9 Nov 2021 12:46:12 +0100 [thread overview]
Message-ID: <20211109114612.GC16363@breakpoint.cc> (raw)
In-Reply-To: <1636457577-43305-1-git-send-email-changliang.wu@smartx.com>
Changliang Wu <changliang.wu@smartx.com> wrote:
> This change is meant to add a control for forwarding skb from local.
> By default, ip forward will not receive the pakcet to/from the local.
> But in some special cases, for example:
> -
> | ovs-bridge gw-port | <----> kube-proxy(iptables) |
> -
> Ovs sends the packet to the gateway, which requires iptables for nat,
> such as kube-proxy (iptables), and then sends it back to the gateway
> through routing for further processing in ovs.
This a very terse description. How does packet end up in forward
after skb->sk assignment?
> diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c
> index 00ec819..06b7e00 100644
> --- a/net/ipv4/ip_forward.c
> +++ b/net/ipv4/ip_forward.c
> @@ -95,9 +95,6 @@ int ip_forward(struct sk_buff *skb)
> if (skb->pkt_type != PACKET_HOST)
> goto drop;
>
> - if (unlikely(skb->sk))
> - goto drop;
> -
Please have a look at
2ab957492d13bb819400ac29ae55911d50a82a13
you need to explain why this is now ok.
Without explanation i have to assume stack will now crash again
when net->ipv4.sysctl_ip_fwd_accept_local=1 and TW socket is assigned.
prev parent reply other threads:[~2021-11-09 11:46 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-09 11:32 [PATCH] ipv4: add sysctl knob to control the discarding of skb from local in ip_forward Changliang Wu
2021-11-09 11:44 ` Daniel Borkmann
2021-11-09 11:46 ` Florian Westphal [this message]
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