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From: Florian Westphal <fw@strlen.de>
To: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Marcelo Ricardo Leitner <mleitner@redhat.com>,
	netfilter-devel@vger.kernel.org
Subject: Re: [PATCH v4 2/3] Do error handling if __build_packet_message fails
Date: Tue, 4 Nov 2014 20:11:20 +0100	[thread overview]
Message-ID: <20141104191120.GC6874@breakpoint.cc> (raw)
In-Reply-To: <20141104182609.GA26344@salvia>

Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> BTW, we should also signal the userspace when we fail to build the
> message via:
> 
> nfnetlink_set_err(net, 0, group, -ENOBUFS);
> 
> so it knows that we're losing log messages for whatever reason.
> Basically, userspace hits -ENOBUFS when calling recv(), which means
> netlink is losing messages. I don't think we really need the
> statistics.

Not sure if this is a good idea.

a) __build_packet_message must never fail.
If it does, the kernel has a size accoutning bug somewhere.
b) I see no meaningful way for userspace to handle this error;
there is nothing it can do about it.
c) If it happens, it might be that some userspace logging daemon
suddently dies because it sees an unexpected 'fatal' error.

> It seems this code needs some care.

Agreed...

  parent reply	other threads:[~2014-11-04 19:11 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-10-29 12:51 [PATCH v4 1/3] netfilter: log: protect nf_log_register against double registering Marcelo Ricardo Leitner
2014-10-29 12:51 ` [PATCH v4 2/3] Do error handling if __build_packet_message fails Marcelo Ricardo Leitner
2014-11-04 16:47   ` Pablo Neira Ayuso
2014-11-04 18:01     ` Marcelo Ricardo Leitner
2014-11-04 18:26       ` Pablo Neira Ayuso
2014-11-04 18:52         ` Marcelo Ricardo Leitner
2014-11-04 19:04           ` Pablo Neira Ayuso
2014-11-04 19:08             ` Marcelo Ricardo Leitner
2014-11-04 19:11         ` Florian Westphal [this message]
2014-11-06  1:07           ` Pablo Neira Ayuso
2014-11-06  2:19             ` Florian Westphal
2014-10-29 12:51 ` [PATCH v4 3/3] Make use of pr_fmt where applicable Marcelo Ricardo Leitner
2014-11-04 16:50   ` Pablo Neira Ayuso
2014-11-04 17:11     ` Marcelo Ricardo Leitner
2014-10-30 16:31 ` [PATCH v4 1/3] netfilter: log: protect nf_log_register against double registering Pablo Neira Ayuso

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