From: Matthew Garrett <matthew.garrett@nebula.com>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
CC: Kees Cook <keescook@chromium.org>, Greg KH <gregkh@linuxfoundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
        "hpa@zytor.com" <hpa@zytor.com>
Subject: Re: [PATCH V3 08/11] kexec: Disable at runtime if the kernel
 enforces module loading restrictions
Thread-Topic: [PATCH V3 08/11] kexec: Disable at runtime if the kernel
 enforces module loading restrictions
Thread-Index: AQHOqQBlTgRtcELUZ0K5HxHj5bQ8FZm7apqAgAC2VJ6AAAFzgA==
Date: Sun, 8 Sep 2013 17:38:13 +0000
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On Sun, 2013-09-08 at 10:32 -0700, James Bottomley wrote:
> On Sun, 2013-09-08 at 17:27 +0000, Matthew Garrett wrote:
> > > It's an argument that CAP_SYS_BOOT is too powerful yes, but if you
> > > recall, I said I keep that one.  In the rather lame analogy, what I do
> > > by giving away CAP_SYS_MODULE and enforcing module signing while keeping
> > > CAP_SYS_BOOT is allow people into my conservatory to play with the
> > > plants but not into my house to steal the silver ... saying CAP_SYS_BOOT
> > > is too powerful doesn't affect that use case because I haven't given
> > > away CAP_SYS_BOOT.
> > 
> > Ok, sorry, I had your meaning inverted. Yes, permitting the loading of
> > signed modules while preventing the use of kexec is a completely
> > reasonable configuration - so reasonable that it's what this patch
> > causes the kernel to do automatically. 
> 
> Well, no, it doesn't because with this patch, *I* can't use kexec ...
> you've just locked me out of my own house.

Hm. Ok, that's a more compelling argument than Greg's. Let me think
about whether there's a convenient way of supporting this.

-- 
Matthew Garrett <matthew.garrett@nebula.com>
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