Re: [PATCH 2/2] net: Implement SO_PASSCGROUP to enable passing cgroup path

From: David Miller
Date: Wed Apr 23 2014 - 13:30:16 EST


From: Vivek Goyal <vgoyal@xxxxxxxxxx>
Date: Wed, 23 Apr 2014 12:45:37 -0400

> On Tue, Apr 15, 2014 at 08:47:54PM -0700, Andy Lutomirski wrote:
>
> [..]
>> Here's an attack against SO_PASSCGROUP, as you implemented it: connect
>> a socket and get someone else to write(2) to it. This isn't very
>> hard. Now you've impersonated.
>
> If this is a problem then I think kernel requires fixing. Because kernel
> will apply all resource management policies based on the cgroup at write(2)
> time and not based on open() time.

Anyways, this is not even worth discussing.

We already agreed that the cgroup passed at write time with SO_PASSGROUP
enabled should be the socket creation time cgroup.

Just like SO_PASSCRED does.

The identity given is thus the one at open() time.
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