Re: [PATCH RFC] Restrictions on module loading

From: Bodo Eggert
Date: Mon Nov 08 2010 - 03:30:58 EST


Dan Rosenberg <drosenberg@xxxxxxxxxxxxx> wrote:

> The below patch replaces the existing "modules_disable" sysctl with a
> finer-grained "modules_restrict" sysctl. By default, this is set at 0,
> which results in no deviation from normal module loading behavior. When
> set to 1, unprivileged users cannot trigger the automatic loading of
> modules. This behavior is based on grsecurity's GRKERNSEC_MODHARDEN
> setting. The current check is against current_uid(), since several
> distributions explicitly remove CAP_SYS_MODULE from root processes, some
> of which incidentally cause (and rely on) the automatic loading of
> modules. I expect this to be a point of discussion.

- Why don't you offer both?

- What about task switches or work queues?

- It might be more like the expected behavior if you'd used:
0: off, 1: modules completely disabled, 2: CAP_SYS_MODULE, 3: uid==0

Many users will forget to look into the documentation or find the current,
stale documentation or just assume a boolean value.

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