linux-kernel - Re: namespace support requires network modules to say "GPL"

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Message-ID: <475451B1.1030006@free.fr>
Date:	Mon, 03 Dec 2007 19:57:53 +0100
From:	Daniel Lezcano <daniel.lezcano@...e.fr>
To:	Ben Greear <greearb@...delatech.com>
CC:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	containers@...ts.osdl.org, Mark Lord <lkml@....ca>,
	Stephen Hemminger <shemminger@...ux-foundation.org>
Subject: Re: namespace support requires network modules to say "GPL"

Ben Greear wrote:
> Eric W. Biederman wrote:
>> Patrick McHardy <kaber@...sh.net> writes:
>>
>>  
>>> Ben Greear wrote:
>>>    
>>>> I have a binary module that uses dev_get_by_name...it's sort of a 
>>>> bridge-like
>>>> thing and
>>>> needs user-space to tell it which device to listen for packets on...
>>>>
>>>> This code doesn't need or care about name-spaces, so I don't see how 
>>>> it could
>>>> really
>>>> be infringing on the author's code (any worse than loading a binary 
>>>> driver
>>>> into the kernel
>>>> ever does).
>>>>       
>>
>> Regardless of infringement it is incompatible with a complete network
>> namespace implementation.  Further it sounds like the module you are
>> describing defines a kernel ABI without being merged and hopes that
>> ABI will still be supportable in the future.  Honestly I think doing so
>> is horrible code maintenance policy.
>>   
> I don't mind if the ABI changes, so long as I can still use something 
> similar.
> 
> The namespace logic is interesting to me in general, but at this point I 
> can't think of a way that
> it actually helps this particular module.  All I really need is a way to 
> grab every frame
> from eth0 and then transmit it to eth1.  I'm currently doing this by 
> finding the netdevice
> and registering a raw-packet protocol (ie, like tcpdump would do).  At 
> least up to 2.6.23,
> this does not require any hacks to the kernel and uses only non GPL 
> exported symbols.
> 
> Based on my understanding of the namespace logic, if I never add any 
> namespaces,
> the general network layout should look similar to how it does today, so 
> I should have
> no logical problem with my module.
> 
>> Once things are largely complete it makes sense to argue with out of
>> tree module authors that because they don't have network namespace
>> support in their modules, their modules are broken.     
> Does this imply that every module that accesses the network code *must* 
> become
> GPL simply because it must interact with namespace logic that is 
> exported as GPL only symbols?

That's right, with init_net's EXPORT_SYMBOL_GPL and dev_get_xx, we 
enforce people to be GPL whatever they didn't asked to have the 
namespaces in their code.

Eric, why can we simply change EXPORT_SYMBOL_GPL to EXPORT_SYMBOL for 
init_net ?


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