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

[James Morris]

On Sat, 27 May 2017, 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. 

Removing needless code is a security feature, ideally.

> 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. There have been a lot of
> trade-offs in getting this working correctly, so I don't have any
> problem with how it looks currently. It's just a collision of
> assumptions between randstruct (omg, you're accessing a randomized
> struct with a different struct!) and the security head list (all
> entries are lists, and we're just initializing them).

Fix randstruct perhaps, rather than modifying kernel code to shut it up.

-- 
James Morris
<jmorris@xxxxxxxxx>