From: Vishwanath Pai <vpai@akamai•com>
To: Pablo Neira Ayuso <pablo@netfilter•org>
Cc: "Lubashev, Igor" <ilubashe@akamai•com>,
"kaber@trash•net" <kaber@trash•net>,
"kadlec@blackhole•kfki.hu" <kadlec@blackhole•kfki.hu>,
"netfilter-devel@vger•kernel.org"
<netfilter-devel@vger•kernel.org>,
"coreteam@netfilter•org" <coreteam@netfilter•org>,
"Hunt, Joshua" <johunt@akamai•com>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>,
"pai.vishwain@gmail•com" <pai.vishwain@gmail•com>
Subject: Re: [PATCH] netfilter/nflog: nflog-range does not truncate packets
Date: Fri, 17 Jun 2016 11:43:35 -0400 [thread overview]
Message-ID: <57641AA7.70709@akamai.com> (raw)
In-Reply-To: <20160617112219.GA3395@salvia>
On 06/17/2016 07:22 AM, Pablo Neira Ayuso wrote:
> On Wed, Jun 15, 2016 at 03:13:15PM +0000, Lubashev, Igor wrote:
>> Vish, Pablo,
>>
>> I wonder about the value of sending more data than a client is
>> willing to consume (setting aside the important fact that the client
>> code crashes due to the extra data).
>>
>> It seems that we should either drop the nflog-range parameter from
>> nflog altogether (and just use the len from the client) or allow
>> nflog-range to further *restrict* the number of bytes sent to the
>> client.
>>
>> The "further restrict" logic would make it easier to build iptables
>> rules that vary nflog-range based on some match conditions, so a
>> single client would get different packet length depending on what
>> rules matched.
>
> Now I understand your usecase. Restricting the size based on match
> conditions sound reasonable to me.
>
> Why don't you add a new userspace option, eg. --nflog-size, that
> specifies this "further restrict" logic?
>
> What I'm proposing is:
>
> 1) If --nflog-range is used, print a message telling: "--nflog-range
> has never worked, ignoring this option."
>
> 2) If --nflog-size is used, set the size in the structure that is
> passed to the kernel, and apply this "further restrict" logic.
>
> 3) Add the flag to the kernel that I suggested. This flag is only set
> via --nflog-size.
>
> Just to clarify: What I'm trying to avoid is breaking the thing for
> users that are using this --nflog-range (even if it doesn't work) and
> then change the behaviour for them.
>
> With the new option, we really validate that the user is exactly
> asking for this "further restrict" logic that you need.
>
> let me know, thanks.
>
Sounds good to me, yes it will definitely change the behavior for users
who are using that parameter (whether intentional or not). I'm OK with
adding a new parameter instead of using --nflog-range. I will send a
patch with these changes.
prev parent reply other threads:[~2016-06-17 15:43 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-02 0:23 [PATCH] netfilter/nflog: nflog-range does not truncate packets Vishwanath Pai
2016-06-06 22:31 ` Pablo Neira Ayuso
2016-06-07 23:06 ` Vishwanath Pai
2016-06-08 12:16 ` Pablo Neira Ayuso
2016-06-09 17:57 ` Vishwanath Pai
2016-06-13 3:40 ` Vishwanath Pai
2016-06-15 12:39 ` Pablo Neira Ayuso
2016-06-15 14:55 ` Vishwanath Pai
2016-06-15 15:13 ` Lubashev, Igor
2016-06-17 11:22 ` Pablo Neira Ayuso
2016-06-17 15:43 ` Vishwanath Pai [this message]
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