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From: Will Deacon <will.deacon@arm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: kernel-hardening@lists.openwall.com,
	Kees Cook <keescook@chromium.org>,
	Greg KH <gregkh@linuxfoundation.org>,
	David Windsor <dave@progbits.org>,
	Elena Reshetova <elena.reshetova@intel.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	"H. Peter Anvin" <h.peter.anvin@intel.com>
Subject: Re: [kernel-hardening] Re: [RFC v4 PATCH 00/13] HARDENED_ATOMIC
Date: Fri, 11 Nov 2016 19:39:47 +0000	[thread overview]
Message-ID: <20161111193947.GA4457@arm.com> (raw)
In-Reply-To: <20161111184744.GQ11945@leverpostej>

On Fri, Nov 11, 2016 at 06:47:44PM +0000, Mark Rutland wrote:
> On Fri, Nov 11, 2016 at 06:46:30PM +0100, Peter Zijlstra wrote:
> > On Fri, Nov 11, 2016 at 09:43:00AM -0800, Kees Cook wrote:
> > > > 1) kref: Used for honest-to-goodness reference counters that want
> > > > overflow protection.  Uses a new type: atomic_nowrap_t that has
> > > > HARDENED_ATOMIC protection.
> > > 
> > > Based on other feedback, it sounds like we're better off with
> > > refcount_t (which kref could be implemented on top of). And refcount_t
> > > would have a limited API: inc, dec_and_test (or whatever is determined
> > > as sanely minimal).
> > > 
> > > > 2) statistical counters: Atomic in all cases, but wraps.
> > > 
> > > Yup. sequence_t seems to make the most sense on naming, I think. If we
> > > want to get crazy, the type could be sequence_wrap_t.
> > 
> > Why? atomic_t is still perfectly fine here, right?
> 
> Having a name that clearly highlights the intended use-case makes it
> much more obvious what the expected semantics are, and when it is being
> abused. If atomic_t were rarely used directly, bad uses are less likely
> to get cargo-culted into new code.

So what? Now somebody with a driver using atomic_t just does
s/atomic_t/sequence_t/. The rename gains us nothing but churn. Whether this
is opt-in or opt-out, somebody *still* has to audit every single use, in
existing code and new code. Doing that audit after a tree-wide rename
doesn't help a bit.

Will

  reply	other threads:[~2016-11-11 19:39 UTC|newest]

Thread overview: 104+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-10 20:24 [kernel-hardening] [RFC v4 PATCH 00/13] HARDENED_ATOMIC Elena Reshetova
2016-11-10 20:24 ` [kernel-hardening] [RFC v4 PATCH 01/13] Add architecture independent hardened atomic base Elena Reshetova
2016-11-10 20:41   ` [kernel-hardening] " David Windsor
2016-11-10 21:09     ` Peter Zijlstra
2016-11-10 21:35   ` Peter Zijlstra
2016-11-11  9:06     ` Reshetova, Elena
2016-11-10 20:24 ` [kernel-hardening] [RFC v4 PATCH 02/13] percpu-refcount: leave atomic counter unprotected Elena Reshetova
2016-11-10 20:24 ` [kernel-hardening] [RFC v4 PATCH 03/13] kernel: identify wrapping atomic usage Elena Reshetova
2016-11-10 21:58   ` [kernel-hardening] " Peter Zijlstra
2016-11-11  8:49     ` [kernel-hardening] " Reshetova, Elena
2016-11-19 13:28   ` [kernel-hardening] " Paul E. McKenney
2016-11-19 21:39     ` Kees Cook
2016-11-21 20:13       ` Paul E. McKenney
2016-11-10 20:24 ` [kernel-hardening] [RFC v4 PATCH 04/13] mm: " Elena Reshetova
2016-11-10 20:24 ` [kernel-hardening] [RFC v4 PATCH 05/13] fs: " Elena Reshetova
2016-11-10 20:24 ` [kernel-hardening] [RFC v4 PATCH 06/13] net: " Elena Reshetova
2016-11-10 20:24 ` [kernel-hardening] [RFC v4 PATCH 07/13] net: atm: " Elena Reshetova
2016-11-10 20:24 ` [kernel-hardening] [RFC v4 PATCH 08/13] security: " Elena Reshetova
2016-11-10 20:24 ` [kernel-hardening] [RFC v4 PATCH 09/13] drivers: identify wrapping atomic usage (part 1/2) Elena Reshetova
2016-11-10 21:48   ` [kernel-hardening] " Will Deacon
2016-11-11  8:57     ` [kernel-hardening] " Reshetova, Elena
2016-11-11 12:35       ` Mark Rutland
2016-11-10 20:24 ` [kernel-hardening] [RFC v4 PATCH 10/13] drivers: identify wrapping atomic usage (part 2/2) Elena Reshetova
2016-11-10 20:24 ` [kernel-hardening] [RFC v4 PATCH 11/13] x86: identify wrapping atomic usage Elena Reshetova
2016-11-10 20:24 ` [kernel-hardening] [RFC v4 PATCH 12/13] x86: implementation for HARDENED_ATOMIC Elena Reshetova
2016-11-10 20:40   ` [kernel-hardening] " Peter Zijlstra
2016-11-10 21:04     ` Kees Cook
2016-11-10 21:16       ` Peter Zijlstra
2016-11-10 21:32         ` Kees Cook
2016-11-10 21:46           ` Peter Zijlstra
2016-11-10 22:50     ` Peter Zijlstra
2016-11-10 23:07       ` Kees Cook
2016-11-10 23:30         ` Peter Zijlstra
2016-11-11  9:32           ` [kernel-hardening] " Reshetova, Elena
2016-11-11 10:29             ` [kernel-hardening] " Peter Zijlstra
2016-11-11 18:00           ` Kees Cook
2016-11-11 20:19             ` Peter Zijlstra
2016-11-10 21:33   ` Peter Zijlstra
2016-11-11  9:20     ` [kernel-hardening] " Reshetova, Elena
2016-11-10 20:24 ` [kernel-hardening] [RFC v4 PATCH 13/13] lkdtm: add tests for atomic over-/underflow Elena Reshetova
2016-11-10 20:37 ` [RFC v4 PATCH 00/13] HARDENED_ATOMIC Peter Zijlstra
2016-11-10 20:37   ` [kernel-hardening] " Peter Zijlstra
2016-11-10 20:48   ` Will Deacon
2016-11-10 20:48     ` [kernel-hardening] " Will Deacon
2016-11-10 21:01     ` Kees Cook
2016-11-10 21:01       ` [kernel-hardening] " Kees Cook
2016-11-10 21:23       ` David Windsor
2016-11-10 21:27         ` Kees Cook
2016-11-10 21:27           ` Kees Cook
2016-11-10 21:39           ` David Windsor
2016-11-10 21:39             ` David Windsor
2016-11-10 21:39         ` Peter Zijlstra
2016-11-10 21:13     ` Peter Zijlstra
2016-11-10 21:13       ` [kernel-hardening] " Peter Zijlstra
2016-11-10 21:23       ` Kees Cook
2016-11-10 21:23         ` [kernel-hardening] " Kees Cook
2016-11-11  4:25         ` Rik van Riel
2016-11-10 22:27       ` Greg KH
2016-11-10 23:15         ` Kees Cook
2016-11-10 23:15           ` Kees Cook
2016-11-10 23:38           ` Greg KH
2016-11-10 23:38             ` Greg KH
2016-11-11  7:50             ` David Windsor
2016-11-11 17:43               ` Kees Cook
2016-11-11 17:46                 ` Peter Zijlstra
2016-11-11 18:04                   ` Kees Cook
2016-11-11 20:17                     ` Peter Zijlstra
2016-11-14 20:31                       ` Kees Cook
2016-11-15  8:01                         ` Peter Zijlstra
2016-11-15 16:50                         ` Rik van Riel
2016-11-15 17:23                           ` Kees Cook
2016-11-16 17:09                             ` Rik van Riel
2016-11-16 17:32                               ` Peter Zijlstra
2016-11-16 17:41                                 ` Rik van Riel
2016-11-16 17:34                               ` Reshetova, Elena
2016-11-17  8:37                                 ` Peter Zijlstra
2016-11-17  9:04                                   ` Reshetova, Elena
2016-11-17  9:36                                     ` Peter Zijlstra
2016-11-17  9:36                                   ` Julia Lawall
2016-11-17 10:16                                     ` Peter Zijlstra
2016-11-17 11:19                                       ` Mark Rutland
2016-11-17 11:32                                         ` Julia Lawall
2016-11-17 12:59                                       ` Julia Lawall
2016-11-11 18:47                   ` Mark Rutland
2016-11-11 19:39                     ` Will Deacon [this message]
2016-11-11 18:31                 ` Mark Rutland
2016-11-11 20:05                   ` Peter Zijlstra
2016-11-15 10:36                     ` Mark Rutland
2016-11-15 11:21                       ` Peter Zijlstra
2016-11-15 18:02                         ` Mark Rutland
2016-11-10 23:57           ` Peter Zijlstra
2016-11-10 23:57             ` Peter Zijlstra
2016-11-11  0:29             ` Colin Vidal
2016-11-11 12:41               ` Mark Rutland
2016-11-11 12:47                 ` Peter Zijlstra
2016-11-11 13:00                   ` Peter Zijlstra
2016-11-11 14:39                     ` Thomas Gleixner
2016-11-11 14:48                       ` Peter Zijlstra
2016-11-11 23:07                     ` Peter Zijlstra
2016-11-13 11:03             ` Greg KH
2016-11-13 11:03               ` Greg KH
2016-11-10 20:56   ` Kees Cook
2016-11-10 20:56     ` [kernel-hardening] " Kees Cook
2016-11-11  3:20     ` David Windsor

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