Re: [PATCH] don't allow CAP_NET_ADMIN to load non-netdev kernelmodules

From: Ben Hutchings
Date: Fri Feb 25 2011 - 14:30:39 EST

On Fri, 2011-02-25 at 11:16 -0800, David Miller wrote:
> From: Ben Hutchings <bhutchings@xxxxxxxxxxxxxx>
> Date: Fri, 25 Feb 2011 19:07:59 +0000
> > You realise that module loading doesn't actually run in the context of
> > request_module(), right?
> Why is that a barrier? We could simply pass a capability mask into
> request_module if necessary.
> It's an implementation detail, and not a deterrant to my suggested
> scheme.

It's not an implementation detail. modprobe currently runs with full
capabilities; your proposal requires its capabilities to be limited to
those of the capabilities of the process that triggered the
request_module() (plus, presumably, CAP_SYS_MODULE).

Now modprobe doesn't have CAP_DAC_OVERRIDE and can't read modprobe
configuration files that belong to users other than root.

It doesn't have CAP_SYS_MKNOD so it can't run hooks that call mknod.



Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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