Re: [kernel-hardening] Re: [PATCH v2 05/20] randstruct: Whitelist struct security_hook_heads cast

[Kees Cook]

On Sat, May 27, 2017 at 3:04 PM, Tetsuo Handa
<penguin-kernel@xxxxxxxxxxxxxxxxxxx> wrote:
> Kees Cook wrote:
>> On Sat, May 27, 2017 at 1:41 AM, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
>> > On Fri, May 26, 2017 at 01:17:09PM -0700, Kees Cook wrote:
>> >> The LSM initialization routines walk security_hook_heads as an array
>> >> of struct list_head instead of via names to avoid a ton of needless
>> >> source. Whitelist this to avoid the false positive warning from the
>> >> plugin:
>> >
>> > I think this crap just needs to be fixed properly.  If not it almost
>> > defeats the protections as the "security" ops are just about everywhere.
>>
>> There's nothing unsafe about 3dfc9b02864b19f4dab376f14479ee4ad1de6c9e,
>> it just avoids tons of needless code. Tetsuo has some other ideas for
>> cleaning it up further, but I don't like it because it removes
>> compile-time verification of function types.
>
> Excuse me, but why you think that compile-time verification of function
> types is removed?
>
> -       { .head = &security_hook_heads.HEAD, .hook = { .HEAD = HOOK } }
> +       { .idx = LSM_##HEAD, .hook = { .HEAD = HOOK } }
>
> This change removes dependency on absolute address of security_hook_heads
> being known at compile-time. If function types of .hook.HEAD and HOOK
> mismatches, the compiler can still warn it.

Sorry, misremembered, that was the other patch. I'll go review this
current one...

-Kees

-- 
Kees Cook
Pixel Security