From: Eric Paris <eparis@redhat.com>
To: Patrick McHardy <kaber@trash.net>
Cc: Hua Zhong <hzhong@gmail.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
davem@davemloft.net, kuznet@ms2.inr.ac.ru, pekkas@netcore.fi,
jmorris@namei.org, yoshfuji@linux-ipv6.org
Subject: Re: [RFC PATCH] network: return errors if we know tcp_connect failed
Date: Mon, 15 Nov 2010 10:47:46 -0500 [thread overview]
Message-ID: <1289836066.14282.7.camel@localhost.localdomain> (raw)
In-Reply-To: <4CE10C2A.1050801@trash.net>
On Mon, 2010-11-15 at 11:32 +0100, Patrick McHardy wrote:
> On 13.11.2010 00:14, Hua Zhong wrote:
> >> On 11.11.2010 22:58, Hua Zhong wrote:
> >>>> Yes, I realize this is little different than if the
> >>>> SYN was dropped in the first network device, but it is different
> >>>> because we know what happened! We know that connect() call failed
> >>>> and that there isn't anything coming back.
> >>>
> >>> I would argue that -j DROP should behave exactly as the packet is
> >> dropped in the network, while -j REJECT should signal the failure to
> >> the application as soon as possible (which it doesn't seem to do).
> >>
> >> It sends an ICMP error or TCP reset. Interpretation is up to TCP.
> >
> > Huh? It's the OUTPUT chain we are talking about. There is no ICMP error or
> > TCP reset.
>
> Of course there is.
>
> ICMP (default):
>
> iptables -A OUTPUT -p tcp -j REJECT
>
> TCP reset:
>
> iptables -A OUTPUT -p tcp -j REJECT --reject-with tcp-reset
>
> The second one will cause a hard error for the connection.
Well I'm (I guess?) surprised that the --reject-with icmp doesn't do
anything with a local outgoing connection but --reject-with tcp-reset
does something like what I'm looking for.
I notice the heavy lifting for this is done in
net/ipv4/netfilter/ipt_REJECT.c::send_rest()
(and something very similar for IPv6)
I really don't want to duplicate that code into SELinux (for obvious
reasons) and I'm wondering if anyone has objections to me making it
available outside of netlink and/or suggestions on how to make that code
available outside of netfilter (aka what header to expose it, and does
it still make logical sense in ipt_REJECT.c or somewhere else?)
-Eric
next prev parent reply other threads:[~2010-11-15 15:48 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-11 21:03 [RFC PATCH] network: return errors if we know tcp_connect failed Eric Paris
2010-11-11 21:14 ` Eric Dumazet
2010-11-11 21:58 ` Hua Zhong
2010-11-12 7:36 ` Patrick McHardy
2010-11-12 23:14 ` Hua Zhong
2010-11-15 10:32 ` Patrick McHardy
2010-11-15 15:47 ` Eric Paris [this message]
2010-11-15 15:57 ` Patrick McHardy
2010-11-15 16:04 ` Patrick McHardy
2010-11-15 16:36 ` Patrick McHardy
2010-11-15 16:46 ` David Miller
2010-11-15 20:00 ` Alexey Kuznetsov
2010-11-12 16:08 ` Eric Paris
2010-11-12 16:15 ` Eric Dumazet
2010-11-12 16:35 ` David Lamparter
2010-11-12 16:53 ` Eric Paris
2010-11-12 16:54 ` Patrick McHardy
2010-11-12 17:57 ` a problem tcp_v4_err() Alexey Kuznetsov
2010-11-12 18:12 ` Eric Dumazet
2010-11-12 18:21 ` Eric Dumazet
2010-11-12 18:27 ` Eric Dumazet
2010-11-12 18:31 ` Alexey Kuznetsov
2010-11-12 18:29 ` Alexey Kuznetsov
2010-11-12 18:33 ` Eric Dumazet
2010-11-12 19:22 ` David Miller
2010-11-12 21:18 ` Eric Dumazet
2010-11-12 21:36 ` David Miller
2010-11-12 21:16 ` [RFC PATCH] network: return errors if we know tcp_connect failed David Lamparter
2010-11-12 21:18 ` David Miller
2010-11-12 17:46 ` Alexey Kuznetsov
2010-11-12 19:28 ` David Miller
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