Re: [RFC][PATCH] IP address restricting cgroup subsystem

From: Grzegorz Nosek <root-AfQBxy1nhrQ00sYp1HPQUA@public•gmane.org>
To: Li Zefan <lizf-BthXqXjhjHXQFUHtdCDX3A@public•gmane.org>
Cc: containers-qjLDD68F18O7TbgM5vRIOg@public•gmane.org,
	netdev-u79uwXL29TY76Z2rM5mHXA@public•gmane.org
Subject: Re: [RFC][PATCH] IP address restricting cgroup subsystem
Date: Wed, 7 Jan 2009 08:38:32 +0100	[thread overview]
Message-ID: <20090107073831.GA23648@megiteam.pl> (raw)
In-Reply-To: <49644526.8030205-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>

On śro, sty 07, 2009 at 02:01:10 +0800, Li Zefan wrote:
> CC: netdev@vger•kernel.org
> 
> I'll review the cgroup part if this patch is regarded as useful.
> 
> Grzegorz Nosek wrote:
> > This is a very simple cgroup subsystem to restrict IP addresses used
> > by member processes. Currently it is limited to IPv4 only but IPv6 (or
> > other protocols) should be easy to implement.
> > 
> > IP addresses are write-once (via /cgroup/.../ipaddr.ipv4 in dotted-quad
> 
> Why they should be write-once ?

No real (technical) reason. Making it read-write would be fine with me.
I wanted to make the restriction a one-way road but I guess I can police
that in userspace (simply don't write anything to the file twice).

However, I think that the restriction should be inherited, so that if
CG1 is bound to e.g. 10.0.0.1, CG1/CG2 must be bound to the same
address. But what would I do then with descendant cgroups? Leave them as
is (breaking the inheritance)? Find them all and change their bound
address behind their back (do we have an API for that?)?

I guess I have the same problem right now, anyway (only once instead of
multiple times), so I'd really appreciate your input on this.

Best regards,
 Grzegorz Nosek
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