From: Florian Westphal <fw@strlen.de>
To: Michal Kubecek <mkubecek@suse.cz>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>,
Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>,
Florian Westphal <fw@strlen.de>,
netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
"Michael S. Tsirkin" <mst@redhat.com>,
Markos Chandras <markos.chandras@suse.com>
Subject: Re: [PATCH nf-next] netfilter: xt_CHECKSUM: avoid bad offload warnings on GSO packets
Date: Thu, 24 Aug 2017 12:51:18 +0200 [thread overview]
Message-ID: <20170824105118.GA15739@breakpoint.cc> (raw)
In-Reply-To: <20170824104824.2C318A0F3A@unicorn.suse.cz>
Michal Kubecek <mkubecek@suse.cz> wrote:
> When --checksum_fill action is applied to a GSO packet, checksum_tg() calls
> skb_checksum_help() which is only meant to be applied to non-GSO packets so
> that it issues a warning.
>
> This can be easily triggered by using e.g.
>
> iptables -t mangle -A OUTPUT -j CHECKSUM --checksum-fill
>
> and sending TCP stream via a device with GSO enabled.
>
> While this can be considered a misconfiguration, I believe the bad offload
> warning is supposed to catch bugs in drivers and networking stack, not
> misconfigured firewalls. So let's ignore such packets and only issue a one
> time warning with pr_warn_once() rather than a WARN with stack trace and
> tainted kernel.
Why issue a warning at all?
What kind of action should be taken upon seeing such warning?
next prev parent reply other threads:[~2017-08-24 10:51 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-24 10:48 [PATCH nf-next] netfilter: xt_CHECKSUM: avoid bad offload warnings on GSO packets Michal Kubecek
2017-08-24 10:51 ` Florian Westphal [this message]
2017-08-24 11:07 ` Michal Kubecek
2017-08-24 13:08 ` Davide Caratti
2017-08-24 13:17 ` Florian Westphal
2017-08-25 9:28 ` Michal Kubecek
2017-08-25 9:40 ` Florian Westphal
2017-08-25 9:43 ` Florian Westphal
2017-08-25 9:21 ` Michal Kubecek
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