linux-kernel - Re: [PATCH] sgi-xp: use designated initializers

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Message-ID: <CAGXu5j+SVnYEm-Rg7sfTJOUjS17-6ppY4qUnMmk7NhtyVmv+Kw@mail.gmail.com>
Date:   Wed, 29 Mar 2017 13:48:29 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Robin Holt <robinmholt@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, Cliff Whickman <cpw@....com>
Subject: Re: [PATCH] sgi-xp: use designated initializers

On Tue, Jan 3, 2017 at 3:19 PM, Kees Cook <keescook@...omium.org> wrote:
> On Wed, Dec 21, 2016 at 8:24 AM, Robin Holt <robinmholt@...il.com> wrote:
>> On Fri, Dec 16, 2016 at 7:01 PM, Kees Cook <keescook@...omium.org> wrote:
>>> Prepare to mark sensitive kernel structures for randomization by making
>>> sure they're using designated initializers. These were identified during
>>> allyesconfig builds of x86, arm, and arm64, with most initializer fixes
>>> extracted from grsecurity.
>>
>> I guess I don't understand the context enough here to give you a
>> Signed-off-by.  Can you give us more background on this randomization?
>
> Sure thing! The randomization is on the order of function pointers in
> all-pointer structures (like struct xpc_interface). As long as the
> memory containing the structure isn't shared externally, this
> randomization should have no operational effect. The reason explicit
> no-op functions were added was to avoid ugly casts, etc.

Friendly ping ... any chance this can land in -next soon?

>> From what I see in the code here, I can see you are providing
>> equivalent functionality and I would give it a signed-off-by, but I am
>> not sure this randomization of which you speak is not going to cause
>> problems for XP, XPC, XPNET, and XPMEM (out of tree GPL kernel
>> module).
>
> Ah, hm, does this module share the structure without being built
> against the kernel? (If built with the kernel, the randomization
> plugin will keep things in the right order.)

Regardless of your answer, this randomization can be turned off.
Switching to designated initializers here is mainly just a clean up.

Thanks!

-Kees

-- 
Kees Cook
Pixel Security