linux-kernel - Re: [PATCH 0/3] creds/cgroups/ns_proxy refcount

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Message-ID: <CAGXu5jJQNdKpU8tSfiWt74aodL5w471unZGzq9RevGd+-wm=wQ@mail.gmail.com>
Date:   Thu, 7 Mar 2019 09:43:25 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Elena Reshetova <elena.reshetova@...el.com>
Cc:     "Eric W. Biederman" <ebiederm@...ssion.com>, serue@...ibm.com,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/3] creds/cgroups/ns_proxy refcount_t conversions

On Wed, Mar 6, 2019 at 3:05 AM Elena Reshetova
<elena.reshetova@...el.com> wrote:
>
> I would like to reopen ages-old discussion on these conversions now.
> Eric had objections against them in past, namely on not providing enough
> security for reference counters (but we still argue it is better
> than overflowing atomic_t and resulting use-after-free).
> However now, refcount_t has been successfully used in kernel in many places,
> helped to detect bugs and mistakes in logic of refcounters.
> We have converted most of core kernel reference counters by now and these
> 3 are pretty core ones, so it would be really great to have them covered
> also.
>
> The patches are fully independent and can be cherry-picked and
> discussed separately. More information about each conversion in each patch
> separately.

These look good to me. Perhaps they can go via -mm, maybe with Eric
and/or Peter's ack/review? I'd really like to get these done so we can
get closer to finishing the refcount_t conversions...

Thanks!

-Kees

>
> Elena Reshetova (3):
>   nsproxy: convert nsproxy.count to refcount_t
>   groups: convert group_info.usage to refcount_t
>   creds: convert cred.usage to refcount_t
>
>  include/linux/cred.h    | 15 +++++++-------
>  include/linux/nsproxy.h |  6 +++---
>  kernel/cred.c           | 44 ++++++++++++++++++++---------------------
>  kernel/groups.c         |  2 +-
>  kernel/nsproxy.c        |  6 +++---
>  net/sunrpc/auth.c       |  2 +-
>  6 files changed, 38 insertions(+), 37 deletions(-)
>
> --
> 2.17.1
>


-- 
Kees Cook