linux-kernel - Re: [PATCH 3/5] Add the ability to lock down access to the running kernel image

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Message-ID: <19783.1495695202@warthog.procyon.org.uk>
Date:   Thu, 25 May 2017 07:53:22 +0100
From:   David Howells <dhowells@...hat.com>
To:     Casey Schaufler <casey@...aufler-ca.com>
Cc:     dhowells@...hat.com, ard.biesheuvel@...aro.org,
        matthew.garrett@...ula.com, linux-security-module@...r.kernel.org,
        linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] Add the ability to lock down access to the running kernel image

Casey Schaufler <casey@...aufler-ca.com> wrote:

> > +#ifdef CONFIG_LOCK_DOWN_KERNEL
> > +extern bool kernel_is_locked_down(void);
> > +#else
> > +static inline bool kernel_is_locked_down(void)
> 
> Should this be a bool or an int? I can imagine that someone is going to want
> various different degrees of lock down for kernels. As an int you could
> return a bitmap indicating which features were locked. This would allow
> additional things to be locked down without changing the interface.

At the moment it makes no difference, since the return value is only ever
passed directly to an if-statement.

Also, do you have an idea as to how is should be divided up?

There aren't so many cases, at least not yet, that they can't be fixed up,
perhaps with a coccinelle script.

David