Re: [PATCH 00/12] One more attempt at useful kernel lockdown

Josh Boyer
2013-09-09T19:52:50Z

On Mon, Sep 9, 2013 at 3:41 PM, H. Peter Anvin <hpa@zytor.com> wrote:
> On 09/09/2013 12:01 PM, Valdis.Kletnieks@vt.edu wrote:
>> On Mon, 09 Sep 2013 11:25:38 -0700, David Lang said:
>>
>>> Given that we know that people want signed binaries without
>>> blocking kexec, you should have '1' just enforce module signing
>>> and '2' (or higher) implement a full lockdown including kexec.
>>
>>> Or, eliminate the -1 permanently insecure option and make this a
>>> bitmask, if someone wants to enable every possible lockdown, have
>>> them set it to "all 1's", define the bits only as you need them.
>>
>> This strikes me as much more workable than one big sledgehammer.
>>
>
> I.e. capabilities ;)

Circles. All I see here are circles.

Having lived an entire release with a capabilities based mechanism for
this in Fedora, please no.

And if you are talking about non-POSIX capabilities as you mentioned
earlier, that seems to be no different than having securelevel being a
bitmask of, well, levels. I don't have much opinion on securelevel
being a big hammer or a bitmask of finer grained things, but I do
think it's a more manageable way forward. Calling the implementation
"capabilities" seems to just be unnecessarily confusing.

josh