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From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Xin Long <lucien.xin@gmail.com>
Cc: network dev <netdev@vger.kernel.org>,
	netfilter-devel@vger.kernel.org,
	Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>,
	Neil Horman <nhorman@tuxdriver.com>
Subject: Re: [PATCH net] netfilter: set skb transport_header before calling sctp_compute_cksum
Date: Fri, 8 Mar 2019 16:50:49 +0100	[thread overview]
Message-ID: <20190308155049.by7f4uzjxqnf3xu7@salvia> (raw)
In-Reply-To: <740683890e28e93c1b2e940a28089ca10f006b7f.1551601041.git.lucien.xin@gmail.com>

Hi,

On Sun, Mar 03, 2019 at 04:17:21PM +0800, Xin Long wrote:
> sctp_hdr(skb) only works when skb->transport_header is set
> properly.
> 
> But in the path of nf_conntrack_in:
> 
>   sctp_packet() -> sctp_error() -> sctp_compute_cksum().
> 
> skb->transport_header is not guaranteed to be right value
> for sctp. It will cause to fail to check the checksum for
> sctp packets.
> 
> So fix it by setting skb transport_header before calling
> sctp_compute_cksum().

I see a few more calls to sctp_compute_cksum() in the netfilter tree.
I guess they are broken too.

In netfilter, skb->transport_header is never set from the input path,
I think this introduces an assymmetry with other transport protocols.

May we have a variant of sctp_compute_cksum() which does not rely on
sctp_hdr() instead?

  reply	other threads:[~2019-03-08 15:50 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-03  8:17 [PATCH net] netfilter: set skb transport_header before calling sctp_compute_cksum Xin Long
2019-03-08 15:50 ` Pablo Neira Ayuso [this message]
2019-03-09  9:07   ` Xin Long
2019-03-09  9:24     ` Florian Westphal
2019-03-11 11:07       ` Neil Horman
2019-03-12  8:39         ` Xin Long
2019-03-12  9:48           ` Pablo Neira Ayuso
2019-03-12 11:01             ` Xin Long

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