From: "H. Peter Anvin" <hpa@zytor.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>,
linux-kernel@vger.kernel.org, x86@kernel.org,
kernel-hardening@lists.openwall.com, adurbin@google.com,
Eric Northup <digitaleric@google.com>,
jln@google.com, wad@google.com,
Mathias Krause <minipli@googlemail.com>,
Zhang Yanfei <zhangyanfei@cn.fujitsu.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Thomas Gleixner <tglx@linutronix.de>
Subject: [kernel-hardening] Re: [PATCH v6 0/7] Kernel base address randomization
Date: Tue, 01 Oct 2013 22:30:58 -0700 [thread overview]
Message-ID: <524BAF92.1090705@zytor.com> (raw)
In-Reply-To: <20131002052531.GA31122@gmail.com>
On 10/01/2013 10:25 PM, Ingo Molnar wrote:
>
> I mean, for example in an oops message we print data in words: the RIP,
> other registers and stack contents. If any of these values lies within the
> randomization range then we could de-randomize it.
>
> So instead of exposing randomized values, we could expose de-randomized
> values.
>
> ( This isn't fool-proof: if some data value happens to lie within the
> random range spuriously then we'll incorrectly transform it. In the
> context of oops messages this should not be a big practical problem
> though. )
>
I don't agree that this isn't a big practical problem. I often find it
necessary to pick out "things that look like pointers". Overall,
derandomization would make it possible to get really confused when you
have things like half a pointer overwritten.
-hpa
WARNING: multiple messages have this Message-ID (diff)
From: "H. Peter Anvin" <hpa@zytor.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>,
linux-kernel@vger.kernel.org, x86@kernel.org,
kernel-hardening@lists.openwall.com, adurbin@google.com,
Eric Northup <digitaleric@google.com>,
jln@google.com, wad@google.com,
Mathias Krause <minipli@googlemail.com>,
Zhang Yanfei <zhangyanfei@cn.fujitsu.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v6 0/7] Kernel base address randomization
Date: Tue, 01 Oct 2013 22:30:58 -0700 [thread overview]
Message-ID: <524BAF92.1090705@zytor.com> (raw)
In-Reply-To: <20131002052531.GA31122@gmail.com>
On 10/01/2013 10:25 PM, Ingo Molnar wrote:
>
> I mean, for example in an oops message we print data in words: the RIP,
> other registers and stack contents. If any of these values lies within the
> randomization range then we could de-randomize it.
>
> So instead of exposing randomized values, we could expose de-randomized
> values.
>
> ( This isn't fool-proof: if some data value happens to lie within the
> random range spuriously then we'll incorrectly transform it. In the
> context of oops messages this should not be a big practical problem
> though. )
>
I don't agree that this isn't a big practical problem. I often find it
necessary to pick out "things that look like pointers". Overall,
derandomization would make it possible to get really confused when you
have things like half a pointer overwritten.
-hpa
next prev parent reply other threads:[~2013-10-02 5:30 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-01 19:37 [kernel-hardening] [PATCH v6 0/7] Kernel base address randomization Kees Cook
2013-10-01 19:37 ` Kees Cook
2013-10-01 19:37 ` [kernel-hardening] [PATCH 1/7] x86, kaslr: move CPU flags out of cpucheck Kees Cook
2013-10-01 19:37 ` Kees Cook
2013-10-01 20:48 ` [kernel-hardening] " H. Peter Anvin
2013-10-01 20:48 ` H. Peter Anvin
2013-10-01 21:09 ` [kernel-hardening] " Kees Cook
2013-10-01 21:09 ` Kees Cook
2013-10-01 19:37 ` [kernel-hardening] [PATCH 2/7] x86, kaslr: return location from decompress_kernel Kees Cook
2013-10-01 19:37 ` Kees Cook
2013-10-01 19:37 ` [kernel-hardening] [PATCH 3/7] x86, kaslr: find minimum safe relocation position Kees Cook
2013-10-01 19:37 ` Kees Cook
2013-10-01 19:37 ` [kernel-hardening] [PATCH 4/7] x86, kaslr: select random base offset Kees Cook
2013-10-01 19:37 ` Kees Cook
2013-10-01 20:46 ` [kernel-hardening] " H. Peter Anvin
2013-10-01 20:46 ` H. Peter Anvin
2013-10-01 21:18 ` [kernel-hardening] " Kees Cook
2013-10-01 21:18 ` Kees Cook
2013-10-01 19:37 ` [kernel-hardening] [PATCH 5/7] x86, kaslr: select memory region from e820 maps Kees Cook
2013-10-01 19:37 ` Kees Cook
2013-10-01 19:37 ` [kernel-hardening] [PATCH 6/7] x86, kaslr: report kernel offset on panic Kees Cook
2013-10-01 19:37 ` Kees Cook
2013-10-02 0:38 ` [kernel-hardening] " HATAYAMA Daisuke
2013-10-02 0:38 ` HATAYAMA Daisuke
2013-10-02 1:06 ` [kernel-hardening] " HATAYAMA Daisuke
2013-10-02 1:06 ` HATAYAMA Daisuke
2013-10-02 7:51 ` [kernel-hardening] " Kees Cook
2013-10-02 7:51 ` Kees Cook
2013-10-02 7:48 ` [kernel-hardening] " Kees Cook
2013-10-02 7:48 ` Kees Cook
2013-10-02 9:13 ` [kernel-hardening] " HATAYAMA Daisuke
2013-10-02 9:13 ` HATAYAMA Daisuke
2013-10-03 0:33 ` [kernel-hardening] " HATAYAMA Daisuke
2013-10-03 0:33 ` HATAYAMA Daisuke
2013-10-03 13:47 ` [kernel-hardening] " Dave Anderson
2013-10-03 13:47 ` Dave Anderson
2013-10-07 1:59 ` [kernel-hardening] " HATAYAMA Daisuke
2013-10-07 1:59 ` HATAYAMA Daisuke
2013-10-07 13:21 ` [kernel-hardening] " Dave Anderson
2013-10-07 13:21 ` Dave Anderson
2013-10-08 9:52 ` [kernel-hardening] " HATAYAMA Daisuke
2013-10-08 9:52 ` HATAYAMA Daisuke
2013-10-08 13:38 ` [kernel-hardening] " Dave Anderson
2013-10-08 13:38 ` Dave Anderson
2013-10-09 10:04 ` [kernel-hardening] " HATAYAMA Daisuke
2013-10-09 10:04 ` HATAYAMA Daisuke
2013-10-09 14:13 ` [kernel-hardening] " H. Peter Anvin
2013-10-09 14:13 ` H. Peter Anvin
2013-10-09 18:06 ` [kernel-hardening] " Kees Cook
2013-10-09 18:06 ` Kees Cook
2013-10-01 19:37 ` [kernel-hardening] [PATCH 7/7] x86, kaslr: raise max positions to 1GiB on x86_64 Kees Cook
2013-10-01 19:37 ` Kees Cook
2013-10-02 5:07 ` [kernel-hardening] Re: [PATCH v6 0/7] Kernel base address randomization Ingo Molnar
2013-10-02 5:07 ` Ingo Molnar
2013-10-02 5:11 ` [kernel-hardening] " H. Peter Anvin
2013-10-02 5:11 ` H. Peter Anvin
2013-10-02 5:25 ` [kernel-hardening] " Ingo Molnar
2013-10-02 5:25 ` Ingo Molnar
2013-10-02 5:30 ` H. Peter Anvin [this message]
2013-10-02 5:30 ` H. Peter Anvin
2013-10-02 5:36 ` [kernel-hardening] " Kees Cook
2013-10-02 5:36 ` 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=524BAF92.1090705@zytor.com \
--to=hpa@zytor.com \
--cc=a.p.zijlstra@chello.nl \
--cc=acme@infradead.org \
--cc=adurbin@google.com \
--cc=akpm@linux-foundation.org \
--cc=digitaleric@google.com \
--cc=jln@google.com \
--cc=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=minipli@googlemail.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=wad@google.com \
--cc=x86@kernel.org \
--cc=zhangyanfei@cn.fujitsu.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.