From: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
To: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Pavel Emelyanov <xemul@parallels.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Andrey Vagin <avagin@openvz.org>, Ingo Molnar <mingo@elte.hu>,
Thomas Gleixner <tglx@linutronix.de>,
Glauber Costa <glommer@parallels.com>,
Andi Kleen <andi@firstfloor.org>, Tejun Heo <tj@kernel.org>,
Matt Helsley <matthltc@us.ibm.com>,
Pekka Enberg <penberg@kernel.org>,
Eric Dumazet <eric.dumazet@gmail.com>,
Vasiliy Kulikov <segoon@openwall.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Valdis.Kletnieks@vt.edu" <Valdis.Kletnieks@vt.edu>
Subject: Re: [RFC] syscalls, x86: Add __NR_kcmp syscall
Date: Wed, 18 Jan 2012 11:46:57 -0500 [thread overview]
Message-ID: <4F16F781.3040700@gmail.com> (raw)
In-Reply-To: <20120118115700.GO1968@moon>
(1/18/12 6:57 AM), Cyrill Gorcunov wrote:
> On Wed, Jan 18, 2012 at 04:23:24AM -0500, KOSAKI Motohiro wrote:
>> (1/18/12 4:19 AM), Pavel Emelyanov wrote:
>>>> I think Eric only said gt/lt compare is useful. We don't need to expose bare
>>>> pointer order. example, kcmp(rotate(ptr, per-task-random-value)) is enough
>>>> hide the critical information. I think.
>>>
>>> The per-task might break thinks up in case
>>>
>>> (tsk1->file != tsk2->file)&& (rotate(tsk1->file, tsk1->random) == rotate(tsk2->file, tsk2->rotate))
>>
>> I meant,
>>
>> (tsk1->file != tsk2->file)&& (rotate(tsk1->file, caller_task->random) == rotate(tsk2->file, caller_task->random))
>>
>>
>>>
>>> but I agree, that the overall idea of comparing not bare pointers, but those poisoned with
>>> some global value can address the Peter's concerns about rootkits.
>
> Guys, can we stick with something simplier? I could use hashes here (again?!) or
> even aes encoded pointers extended to 128 bits as it was proposed too. But
> maybe we can live with something more simplier?
The problem of hashes is,
- SHA1 didn't provide correct "equal or not" policy. (and I don't think sha1 is faster than kcmp)
- Poisoned pointer can be used to restore original bare pointer.
Do this have the same issue?
> We could export EQ/NE for regular users (which might be usefull for less
> frequently used objects such as namespaces I guess). And GT/LT for root
> only.
>
> Does it look better? Does the change log tells enough?
I dislike. Just EQ/NE is better than "root only" behavior change. it's misleading.
If you dislike GT/LT, please just delete it.
next prev parent reply other threads:[~2012-01-18 16:47 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-17 14:27 [RFC] syscalls, x86: Add __NR_kcmp syscall Cyrill Gorcunov
2012-01-17 14:38 ` Alexey Dobriyan
2012-01-17 14:44 ` Cyrill Gorcunov
2012-01-17 18:47 ` H. Peter Anvin
2012-01-17 21:15 ` Cyrill Gorcunov
2012-01-17 21:40 ` Eric W. Biederman
2012-01-18 5:07 ` Pavel Emelyanov
2012-01-17 21:35 ` Eric W. Biederman
2012-01-18 8:01 ` Cyrill Gorcunov
2012-01-18 9:12 ` KOSAKI Motohiro
2012-01-18 9:19 ` Pavel Emelyanov
2012-01-18 9:23 ` KOSAKI Motohiro
2012-01-18 11:57 ` Cyrill Gorcunov
2012-01-18 16:46 ` KOSAKI Motohiro [this message]
2012-01-18 17:20 ` Cyrill Gorcunov
2012-01-18 22:05 ` david
2012-01-18 22:49 ` Cyrill Gorcunov
2012-01-18 23:29 ` Eric W. Biederman
2012-01-19 6:55 ` Cyrill Gorcunov
2012-01-20 3:16 ` Eric W. Biederman
2012-01-20 8:40 ` Cyrill Gorcunov
2012-01-20 9:02 ` Cyrill Gorcunov
2012-01-20 14:51 ` H. Peter Anvin
2012-01-20 16:29 ` Cyrill Gorcunov
2012-01-20 16:57 ` H. Peter Anvin
2012-01-20 18:19 ` Cyrill Gorcunov
2012-01-20 18:22 ` Cyrill Gorcunov
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=4F16F781.3040700@gmail.com \
--to=kosaki.motohiro@gmail.com \
--cc=Valdis.Kletnieks@vt.edu \
--cc=adobriyan@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=andi@firstfloor.org \
--cc=avagin@openvz.org \
--cc=ebiederm@xmission.com \
--cc=eric.dumazet@gmail.com \
--cc=glommer@parallels.com \
--cc=gorcunov@gmail.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=matthltc@us.ibm.com \
--cc=mingo@elte.hu \
--cc=penberg@kernel.org \
--cc=segoon@openwall.com \
--cc=tglx@linutronix.de \
--cc=tj@kernel.org \
--cc=xemul@parallels.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).