All of lore.kernel.org
 help / color / mirror / Atom feed
From: Kees Cook <keescook@chromium.org>
To: Jann Horn <jann@thejh.net>
Cc: "kernel-hardening@lists.openwall.com"
	<kernel-hardening@lists.openwall.com>,
	David Windsor <dwindsor@gmail.com>,
	Hans Liljestrand <ishkamiel@gmail.com>,
	Elena Reshetova <elena.reshetova@intel.com>
Subject: Re: [kernel-hardening] [RFC PATCH 05/13] fs: identify wrapping atomic usage
Date: Mon, 3 Oct 2016 15:21:10 -0700	[thread overview]
Message-ID: <CAGXu5jKXcmWpryk=-yuySapqLsV_qTff3+Q1VvM38d+UsV4Gdg@mail.gmail.com> (raw)
In-Reply-To: <20161003215739.GO14666@pc.thejh.net>

On Mon, Oct 3, 2016 at 2:57 PM, Jann Horn <jann@thejh.net> wrote:
> On Mon, Oct 03, 2016 at 09:41:18AM +0300, Elena Reshetova wrote:
>> From: David Windsor <dwindsor@gmail.com>
>>
>> In some cases atomic is not used for reference
>> counting and therefore should be allowed to overflow.
>> Identify such cases and make a switch to non-hardened
>> atomic version.
>
> Depending on what the overhead ends up being, it might make sense to opt
> f_count in struct file out of the protection. It is the hottest user of
> atomic_t/atomic_long_t that I know of (incremented and decremented for
> every operation on a file descriptor in a multithreaded process), it is
> 64 bits wide and it's only incremented and decremented in steps of 1.

That's certainly an option, but I'd like to see benchmarks before we
start optimizing. :) If we can retain full coverage, that'd be
preferable.

-Kees

-- 
Kees Cook
Nexus Security

  reply	other threads:[~2016-10-03 22:21 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-03  6:41 [kernel-hardening] [RFC PATCH 00/13] HARDENING_ATOMIC feature Elena Reshetova
2016-10-03  6:41 ` [kernel-hardening] [RFC PATCH 01/13] Add architecture independent hardened atomic base Elena Reshetova
2016-10-03 21:10   ` [kernel-hardening] " Kees Cook
2016-10-03 21:26     ` David Windsor
2016-10-03 21:38       ` Kees Cook
2016-10-04  7:05         ` [kernel-hardening] " Reshetova, Elena
2016-10-05 15:37           ` [kernel-hardening] " Dave Hansen
2016-10-04  7:07         ` [kernel-hardening] " Reshetova, Elena
2016-10-04  6:54       ` Reshetova, Elena
2016-10-04  7:23       ` Reshetova, Elena
2016-10-12  8:26     ` [kernel-hardening] " AKASHI Takahiro
2016-10-12 17:25       ` Reshetova, Elena
2016-10-12 22:50         ` Kees Cook
2016-10-13 14:31           ` Hans Liljestrand
2016-10-03  6:41 ` [kernel-hardening] [RFC PATCH 02/13] percpu-refcount: leave atomic counter unprotected Elena Reshetova
2016-10-03 21:12   ` [kernel-hardening] " Kees Cook
2016-10-04  6:24     ` [kernel-hardening] " Reshetova, Elena
2016-10-04 13:06       ` [kernel-hardening] " Hans Liljestrand
2016-10-03  6:41 ` [kernel-hardening] [RFC PATCH 03/13] kernel: identify wrapping atomic usage Elena Reshetova
2016-10-03 21:13   ` [kernel-hardening] " Kees Cook
2016-10-04  6:28     ` [kernel-hardening] " Reshetova, Elena
2016-10-03  6:41 ` [kernel-hardening] [RFC PATCH 04/13] mm: " Elena Reshetova
2016-10-03  6:41 ` [kernel-hardening] [RFC PATCH 05/13] fs: " Elena Reshetova
2016-10-03 21:57   ` Jann Horn
2016-10-03 22:21     ` Kees Cook [this message]
2016-10-03  6:41 ` [kernel-hardening] [RFC PATCH 06/13] net: " Elena Reshetova
2016-10-03  6:41 ` [kernel-hardening] [RFC PATCH 07/13] net: atm: " Elena Reshetova
2016-10-03  6:41 ` [kernel-hardening] [RFC PATCH 08/13] security: " Elena Reshetova
2016-10-03  6:41 ` [kernel-hardening] [RFC PATCH 09/13] drivers: identify wrapping atomic usage (part 1/2) Elena Reshetova
2016-10-03  6:41 ` [kernel-hardening] [RFC PATCH 10/13] drivers: identify wrapping atomic usage (part 2/2) Elena Reshetova
2016-10-03  6:41 ` [kernel-hardening] [RFC PATCH 11/13] x86: identify wrapping atomic usage Elena Reshetova
2016-10-03  6:41 ` [kernel-hardening] [RFC PATCH 12/13] x86: x86 implementation for HARDENED_ATOMIC Elena Reshetova
2016-10-03  9:47   ` Jann Horn
2016-10-04  7:15     ` Reshetova, Elena
2016-10-04 12:46       ` Jann Horn
2016-10-03 19:27   ` Dave Hansen
2016-10-03 22:49     ` David Windsor
2016-10-04 12:41     ` Jann Horn
2016-10-04 18:51       ` Kees Cook
2016-10-04 19:48         ` Jann Horn
2016-10-05 15:39       ` Dave Hansen
2016-10-05 16:18         ` Jann Horn
2016-10-05 16:32           ` Dave Hansen
2016-10-03 21:29   ` [kernel-hardening] " Kees Cook
2016-10-03  6:41 ` [kernel-hardening] [RFC PATCH 13/13] lkdtm: add tests for atomic over-/underflow Elena Reshetova
2016-10-03 21:35   ` [kernel-hardening] " Kees Cook
2016-10-04  6:27     ` [kernel-hardening] " Reshetova, Elena
2016-10-04  6:40       ` [kernel-hardening] " Hans Liljestrand
2016-10-03  8:14 ` [kernel-hardening] [RFC PATCH 00/13] HARDENING_ATOMIC feature AKASHI Takahiro
2016-10-03  8:13   ` Reshetova, Elena
2016-10-03 21:01 ` [kernel-hardening] " Kees Cook

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAGXu5jKXcmWpryk=-yuySapqLsV_qTff3+Q1VvM38d+UsV4Gdg@mail.gmail.com' \
    --to=keescook@chromium.org \
    --cc=dwindsor@gmail.com \
    --cc=elena.reshetova@intel.com \
    --cc=ishkamiel@gmail.com \
    --cc=jann@thejh.net \
    --cc=kernel-hardening@lists.openwall.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.