From: Florian Westphal <fw@strlen.de>
To: Ursula Braun <ubraun@linux.vnet.ibm.com>
Cc: David Miller <davem@davemloft.net>,
netdev@vger.kernel.org, linux-s390@vger.kernel.org,
jwi@linux.vnet.ibm.com, schwidefsky@de.ibm.com,
heiko.carstens@de.ibm.com, raspl@linux.vnet.ibm.com,
hwippel@linux.vnet.ibm.com
Subject: Re: [PATCH net-next 1/1] net/smc: add SMC rendezvous protocol
Date: Thu, 12 Oct 2017 13:14:29 +0200 [thread overview]
Message-ID: <20171012111429.GG26835@breakpoint.cc> (raw)
In-Reply-To: <b37b38df-cbb8-ca86-d460-9d3ec7acc2c6@linux.vnet.ibm.com>
Ursula Braun <ubraun@linux.vnet.ibm.com> wrote:
> On 10/11/2017 11:06 PM, David Miller wrote:
> > From: Ursula Braun <ubraun@linux.vnet.ibm.com>
> > Date: Tue, 10 Oct 2017 16:14:19 +0200
> >
> >> The goal of this patch is to leave common TCP code unmodified. Thus,
> >> it uses netfilter hooks to intercept TCP SYN and SYN/ACK
> >> packets. For outgoing packets originating from SMC sockets, the
> >> experimental option is added. For inbound packets destined for SMC
> >> sockets, the experimental option is checked.
> >
> > I think this really isn't going to pass.
> >
> > It's a user experience nightmare when the kernel inserts and
> > deletes filtering rules outside of what the user configures
> > on their system.
It depends if the hook is passive or not (i.e. mangles
payload/metadata or returns verdict other than NF_ACCEPT).
OUTPUT hook added here is not passive as it mangles tcp options.
> > This approach was also considerd for ipv6 ILA, and the same
> > pushback was given.
ahem.
net/ipv6/ila/ila_xlat.c: err = nf_register_net_hooks(net, ila_nf_hook_ops,
FWIW at least the input hook seems ok to me provided it would use
skb_header_pointer for tcp header access (there is no guarantee
tcp_hdr() works or that the tcp header has been sanity checked in any
way).
Perhaps its time to consider moving net/netfilter/core.c into net/core
and rename NF_HOOK to NET_HOOK?
next prev parent reply other threads:[~2017-10-12 11:14 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-10 14:14 [PATCH net-next 1/1] net/smc: add SMC rendezvous protocol Ursula Braun
2017-10-11 21:06 ` David Miller
2017-10-12 10:48 ` Ursula Braun
2017-10-12 11:14 ` Florian Westphal [this message]
2017-10-13 6:06 ` David Miller
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