From: Solar Designer <solar@openwall.com>
To: Yann Droneaud <ydroneaud@opteya.com>
Cc: riel@redhat.com, linux-kernel@vger.kernel.org,
danielmicay@gmail.com, tytso@mit.edu, keescook@chromium.org,
hpa@zytor.com, luto@amacapital.net, mingo@kernel.org,
x86@kernel.org, linux-arm-kernel@lists.infradead.org,
catalin.marinas@arm.com, linux-sh@vger.kernel.org,
ysato@users.sourceforge.jp, kernel-hardening@lists.openwall.com
Subject: Re: [kernel-hardening] [PATCH v2 0/5] stackprotector: ascii armor the stack canary
Date: Wed, 20 Sep 2017 15:03:29 +0000 [thread overview]
Message-ID: <20170920150329.GA7017@openwall.com> (raw)
In-Reply-To: <1505906284.3490.5.camel@opteya.com>
On Wed, Sep 20, 2017 at 01:18:04PM +0200, Yann Droneaud wrote:
> Le mardi 19 septembre 2017 ?? 19:16 +0200, Solar Designer a ??crit :
> >
> > We could put/require a NUL in the middle of the canary,
> > but with the full canary being only 64-bit at most that would also
> > make some attacks easier.
>
> Are you suggesting to randomly select which byte to set to 0 in each
> canary ?
Definitely not. That's only 8 different possibilities per canary, and
the weakest one will affect exploitability in each scenario. So that
would be a fairly clear change to the worse.
I suggest that we make no further changes at this time, unless someone
comes up with an idea that would clearly hurt exploitation more than it
helps exploitation, overall across different scenarios.
Alexander
WARNING: multiple messages have this Message-ID (diff)
From: Solar Designer <solar@openwall.com>
To: Yann Droneaud <ydroneaud@opteya.com>
Cc: riel@redhat.com, linux-kernel@vger.kernel.org,
danielmicay@gmail.com, tytso@mit.edu, keescook@chromium.org,
hpa@zytor.com, luto@amacapital.net, mingo@kernel.org,
x86@kernel.org, linux-arm-kernel@lists.infradead.org,
catalin.marinas@arm.com, linux-sh@vger.kernel.org,
ysato@users.sourceforge.jp, kernel-hardening@lists.openwall.com
Subject: Re: [kernel-hardening] [PATCH v2 0/5] stackprotector: ascii armor the stack canary
Date: Wed, 20 Sep 2017 17:03:29 +0200 [thread overview]
Message-ID: <20170920150329.GA7017@openwall.com> (raw)
In-Reply-To: <1505906284.3490.5.camel@opteya.com>
On Wed, Sep 20, 2017 at 01:18:04PM +0200, Yann Droneaud wrote:
> Le mardi 19 septembre 2017 ?? 19:16 +0200, Solar Designer a ??crit :
> >
> > We could put/require a NUL in the middle of the canary,
> > but with the full canary being only 64-bit at most that would also
> > make some attacks easier.
>
> Are you suggesting to randomly select which byte to set to 0 in each
> canary ?
Definitely not. That's only 8 different possibilities per canary, and
the weakest one will affect exploitability in each scenario. So that
would be a fairly clear change to the worse.
I suggest that we make no further changes at this time, unless someone
comes up with an idea that would clearly hurt exploitation more than it
helps exploitation, overall across different scenarios.
Alexander
WARNING: multiple messages have this Message-ID (diff)
From: solar@openwall.com (Solar Designer)
To: linux-arm-kernel@lists.infradead.org
Subject: [kernel-hardening] [PATCH v2 0/5] stackprotector: ascii armor the stack canary
Date: Wed, 20 Sep 2017 17:03:29 +0200 [thread overview]
Message-ID: <20170920150329.GA7017@openwall.com> (raw)
In-Reply-To: <1505906284.3490.5.camel@opteya.com>
On Wed, Sep 20, 2017 at 01:18:04PM +0200, Yann Droneaud wrote:
> Le mardi 19 septembre 2017 ?? 19:16 +0200, Solar Designer a ??crit :
> >
> > We could put/require a NUL in the middle of the canary,
> > but with the full canary being only 64-bit at most that would also
> > make some attacks easier.
>
> Are you suggesting to randomly select which byte to set to 0 in each
> canary ?
Definitely not. That's only 8 different possibilities per canary, and
the weakest one will affect exploitability in each scenario. So that
would be a fairly clear change to the worse.
I suggest that we make no further changes at this time, unless someone
comes up with an idea that would clearly hurt exploitation more than it
helps exploitation, overall across different scenarios.
Alexander
next prev parent reply other threads:[~2017-09-20 15:03 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-24 15:57 [PATCH v2 0/5] stackprotector: ascii armor the stack canary riel
2017-05-24 15:57 ` [kernel-hardening] " riel
2017-05-24 15:57 ` riel at redhat.com
2017-05-24 15:57 ` riel
2017-05-24 15:57 ` [PATCH 1/5] random,stackprotect: introduce get_random_canary function riel
2017-05-24 15:57 ` [kernel-hardening] " riel
2017-05-24 15:57 ` [PATCH 1/5] random, stackprotect: " riel at redhat.com
2017-05-24 15:57 ` [PATCH 1/5] random,stackprotect: " riel
2017-05-24 16:15 ` Kees Cook
2017-05-24 16:15 ` [kernel-hardening] " Kees Cook
2017-05-24 16:15 ` [PATCH 1/5] random, stackprotect: " Kees Cook
2017-05-24 16:15 ` [PATCH 1/5] random,stackprotect: " Kees Cook
2017-05-24 15:57 ` [PATCH 2/5] fork,random: use get_random_canary to set tsk->stack_canary riel
2017-05-24 15:57 ` [kernel-hardening] " riel
2017-05-24 15:57 ` [PATCH 2/5] fork, random: " riel at redhat.com
2017-05-24 15:57 ` [PATCH 2/5] fork,random: " riel
2017-05-24 16:16 ` Kees Cook
2017-05-24 16:16 ` [kernel-hardening] " Kees Cook
2017-05-24 16:16 ` [PATCH 2/5] fork, random: " Kees Cook
2017-05-24 16:16 ` [PATCH 2/5] fork,random: " Kees Cook
2017-05-24 15:57 ` [PATCH 3/5] x86: ascii armor the x86_64 boot init stack canary riel
2017-05-24 15:57 ` [kernel-hardening] " riel
2017-05-24 15:57 ` riel at redhat.com
2017-05-24 15:57 ` riel
2017-05-24 16:16 ` Kees Cook
2017-05-24 16:16 ` [kernel-hardening] " Kees Cook
2017-05-24 16:16 ` Kees Cook
2017-05-24 16:16 ` Kees Cook
2017-05-24 15:57 ` [PATCH 4/5] arm64: ascii armor the arm64 " riel
2017-05-24 15:57 ` [kernel-hardening] " riel
2017-05-24 15:57 ` riel at redhat.com
2017-05-24 15:57 ` riel
2017-05-24 16:16 ` Kees Cook
2017-05-24 16:16 ` [kernel-hardening] " Kees Cook
2017-05-24 16:16 ` Kees Cook
2017-05-24 16:16 ` Kees Cook
2017-05-24 15:57 ` [PATCH 5/5] sh64: ascii armor the sh64 " riel
2017-05-24 15:57 ` [kernel-hardening] " riel
2017-05-24 15:57 ` riel at redhat.com
2017-05-24 15:57 ` riel
2017-05-24 16:34 ` Rik van Riel
2017-05-24 16:34 ` [kernel-hardening] " Rik van Riel
2017-05-24 16:34 ` Rik van Riel
2017-05-24 16:34 ` Rik van Riel
2017-05-24 16:35 ` Kees Cook
2017-05-24 16:35 ` [kernel-hardening] " Kees Cook
2017-05-24 16:35 ` Kees Cook
2017-05-24 16:35 ` Kees Cook
2017-09-19 17:16 ` [kernel-hardening] [PATCH v2 0/5] stackprotector: ascii armor the " Solar Designer
2017-09-19 17:16 ` Solar Designer
2017-09-19 17:16 ` Solar Designer
2017-09-19 20:22 ` Kees Cook
2017-09-19 20:22 ` Kees Cook
2017-09-19 20:22 ` Kees Cook
2017-09-19 20:22 ` Kees Cook
2017-09-19 21:10 ` Daniel Micay
2017-09-19 21:10 ` Daniel Micay
2017-09-19 21:10 ` Daniel Micay
2017-09-20 11:18 ` Yann Droneaud
2017-09-20 11:18 ` Yann Droneaud
2017-09-20 11:18 ` Yann Droneaud
2017-09-20 15:03 ` Solar Designer [this message]
2017-09-20 15:03 ` Solar Designer
2017-09-20 15:03 ` Solar Designer
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