From: Mark Rutland <mark.rutland@arm.com>
To: Laura Abbott <labbott@redhat.com>
Cc: Kees Cook <keescook@chromium.org>,
linux-kernel@vger.kernel.org, ard.biesheuvel@linaro.org,
catalin.marinas@arm.com, james.morse@arm.com,
luto@amacapital.net, matt@codeblueprint.co.uk,
will.deacon@arm.com, kernel-hardening@lists.openwall.com,
linux-arm-kernel@lists.infradead.org
Subject: [kernel-hardening] Re: [PATCH] lkdtm: Test VMAP_STACK allocates leading/trailing guard pages
Date: Tue, 8 Aug 2017 10:23:48 +0100 [thread overview]
Message-ID: <20170808092348.GA19207@leverpostej> (raw)
In-Reply-To: <0e9a80c2-3e5e-db98-dff6-b45e9e4817fd@redhat.com>
On Mon, Aug 07, 2017 at 03:55:22PM -0700, Laura Abbott wrote:
> On 08/07/2017 03:00 PM, Mark Rutland wrote:
> > On Mon, Aug 07, 2017 at 01:39:48PM -0700, Kees Cook wrote:
> >> Do these tests both trip with the new arm64 VMAP_STACK code?
> >
> >> +/* Test that VMAP_STACK is actually allocating with a leading guard page */
> >> +void lkdtm_STACK_GUARD_PAGE_LEADING(void)
> >> +/* Test that VMAP_STACK is actually allocating with a trailing guard page */
> >> +void lkdtm_STACK_GUARD_PAGE_TRAILING(void)
> > I can give these a go tomorrow.
> >
> > These *should* fault, and IIUC should trigger the usual "Unable to handle
> > kernel %s at virtual address %08lx\n" splat from arm64's __do_kernel_fault(),
> > which should end up with an Oops().
> I gave these a quick test in QEMU and they seem to do the correct thing:
> # echo STACK_GUARD_PAGE_LEADING > /sys/kernel/debug/provoke-crash/DIRECT
> [ 24.593306] lkdtm: Performing direct entry STACK_GUARD_PAGE_LEADING
> [ 24.593780] lkdtm: attempting bad read from page below current stack
> [ 24.594289] Unable to handle kernel paging request at virtual address ffff000009b77fff
> [ 24.594747] swapper pgtable: 4k pages, 48-bit VAs, pgd = ffff000009050000
> [ 24.595443] [ffff000009b77fff] *pgd=000000007effe003, *pud=000000007effd003, *pmd=000000007cc43003, *pte=0000000000000000
> [ 24.596743] Internal error: Oops: 96000007 [#1] PREEMPT SMP
> # echo STACK_GUARD_PAGE_TRAILING > /sys/kernel/debug/provoke-crash/DIRECT
> [ 103.144313] lkdtm: Performing direct entry STACK_GUARD_PAGE_TRAILING
> [ 103.144749] lkdtm: attempting bad read from page above current stack
> [ 103.145100] Unable to handle kernel paging request at virtual address ffff000009c2c000
> [ 103.145477] swapper pgtable: 4k pages, 48-bit VAs, pgd = ffff000009050000
> [ 103.145836] [ffff000009c2c000] *pgd=000000007effe003, *pud=000000007effd003, *pmd=000000007d014003, *pte=0000000000000000
> [ 103.146445] Internal error: Oops: 96000007 [#2] PREEMPT SMP
Great! thanks for giving those a spin.
I can confirm likewise on Juno with 64K pages (not that this should make
any difference).
Mark.
WARNING: multiple messages have this Message-ID (diff)
From: mark.rutland@arm.com (Mark Rutland)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] lkdtm: Test VMAP_STACK allocates leading/trailing guard pages
Date: Tue, 8 Aug 2017 10:23:48 +0100 [thread overview]
Message-ID: <20170808092348.GA19207@leverpostej> (raw)
In-Reply-To: <0e9a80c2-3e5e-db98-dff6-b45e9e4817fd@redhat.com>
On Mon, Aug 07, 2017 at 03:55:22PM -0700, Laura Abbott wrote:
> On 08/07/2017 03:00 PM, Mark Rutland wrote:
> > On Mon, Aug 07, 2017 at 01:39:48PM -0700, Kees Cook wrote:
> >> Do these tests both trip with the new arm64 VMAP_STACK code?
> >
> >> +/* Test that VMAP_STACK is actually allocating with a leading guard page */
> >> +void lkdtm_STACK_GUARD_PAGE_LEADING(void)
> >> +/* Test that VMAP_STACK is actually allocating with a trailing guard page */
> >> +void lkdtm_STACK_GUARD_PAGE_TRAILING(void)
> > I can give these a go tomorrow.
> >
> > These *should* fault, and IIUC should trigger the usual "Unable to handle
> > kernel %s at virtual address %08lx\n" splat from arm64's __do_kernel_fault(),
> > which should end up with an Oops().
> I gave these a quick test in QEMU and they seem to do the correct thing:
> # echo STACK_GUARD_PAGE_LEADING > /sys/kernel/debug/provoke-crash/DIRECT
> [ 24.593306] lkdtm: Performing direct entry STACK_GUARD_PAGE_LEADING
> [ 24.593780] lkdtm: attempting bad read from page below current stack
> [ 24.594289] Unable to handle kernel paging request at virtual address ffff000009b77fff
> [ 24.594747] swapper pgtable: 4k pages, 48-bit VAs, pgd = ffff000009050000
> [ 24.595443] [ffff000009b77fff] *pgd=000000007effe003, *pud=000000007effd003, *pmd=000000007cc43003, *pte=0000000000000000
> [ 24.596743] Internal error: Oops: 96000007 [#1] PREEMPT SMP
> # echo STACK_GUARD_PAGE_TRAILING > /sys/kernel/debug/provoke-crash/DIRECT
> [ 103.144313] lkdtm: Performing direct entry STACK_GUARD_PAGE_TRAILING
> [ 103.144749] lkdtm: attempting bad read from page above current stack
> [ 103.145100] Unable to handle kernel paging request at virtual address ffff000009c2c000
> [ 103.145477] swapper pgtable: 4k pages, 48-bit VAs, pgd = ffff000009050000
> [ 103.145836] [ffff000009c2c000] *pgd=000000007effe003, *pud=000000007effd003, *pmd=000000007d014003, *pte=0000000000000000
> [ 103.146445] Internal error: Oops: 96000007 [#2] PREEMPT SMP
Great! thanks for giving those a spin.
I can confirm likewise on Juno with 64K pages (not that this should make
any difference).
Mark.
WARNING: multiple messages have this Message-ID (diff)
From: Mark Rutland <mark.rutland@arm.com>
To: Laura Abbott <labbott@redhat.com>
Cc: Kees Cook <keescook@chromium.org>,
linux-kernel@vger.kernel.org, ard.biesheuvel@linaro.org,
catalin.marinas@arm.com, james.morse@arm.com,
luto@amacapital.net, matt@codeblueprint.co.uk,
will.deacon@arm.com, kernel-hardening@lists.openwall.com,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] lkdtm: Test VMAP_STACK allocates leading/trailing guard pages
Date: Tue, 8 Aug 2017 10:23:48 +0100 [thread overview]
Message-ID: <20170808092348.GA19207@leverpostej> (raw)
In-Reply-To: <0e9a80c2-3e5e-db98-dff6-b45e9e4817fd@redhat.com>
On Mon, Aug 07, 2017 at 03:55:22PM -0700, Laura Abbott wrote:
> On 08/07/2017 03:00 PM, Mark Rutland wrote:
> > On Mon, Aug 07, 2017 at 01:39:48PM -0700, Kees Cook wrote:
> >> Do these tests both trip with the new arm64 VMAP_STACK code?
> >
> >> +/* Test that VMAP_STACK is actually allocating with a leading guard page */
> >> +void lkdtm_STACK_GUARD_PAGE_LEADING(void)
> >> +/* Test that VMAP_STACK is actually allocating with a trailing guard page */
> >> +void lkdtm_STACK_GUARD_PAGE_TRAILING(void)
> > I can give these a go tomorrow.
> >
> > These *should* fault, and IIUC should trigger the usual "Unable to handle
> > kernel %s at virtual address %08lx\n" splat from arm64's __do_kernel_fault(),
> > which should end up with an Oops().
> I gave these a quick test in QEMU and they seem to do the correct thing:
> # echo STACK_GUARD_PAGE_LEADING > /sys/kernel/debug/provoke-crash/DIRECT
> [ 24.593306] lkdtm: Performing direct entry STACK_GUARD_PAGE_LEADING
> [ 24.593780] lkdtm: attempting bad read from page below current stack
> [ 24.594289] Unable to handle kernel paging request at virtual address ffff000009b77fff
> [ 24.594747] swapper pgtable: 4k pages, 48-bit VAs, pgd = ffff000009050000
> [ 24.595443] [ffff000009b77fff] *pgd=000000007effe003, *pud=000000007effd003, *pmd=000000007cc43003, *pte=0000000000000000
> [ 24.596743] Internal error: Oops: 96000007 [#1] PREEMPT SMP
> # echo STACK_GUARD_PAGE_TRAILING > /sys/kernel/debug/provoke-crash/DIRECT
> [ 103.144313] lkdtm: Performing direct entry STACK_GUARD_PAGE_TRAILING
> [ 103.144749] lkdtm: attempting bad read from page above current stack
> [ 103.145100] Unable to handle kernel paging request at virtual address ffff000009c2c000
> [ 103.145477] swapper pgtable: 4k pages, 48-bit VAs, pgd = ffff000009050000
> [ 103.145836] [ffff000009c2c000] *pgd=000000007effe003, *pud=000000007effd003, *pmd=000000007d014003, *pte=0000000000000000
> [ 103.146445] Internal error: Oops: 96000007 [#2] PREEMPT SMP
Great! thanks for giving those a spin.
I can confirm likewise on Juno with 64K pages (not that this should make
any difference).
Mark.
next prev parent reply other threads:[~2017-08-08 9:23 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-07 20:39 [kernel-hardening] [PATCH] lkdtm: Test VMAP_STACK allocates leading/trailing guard pages Kees Cook
2017-08-07 20:39 ` Kees Cook
2017-08-07 20:39 ` Kees Cook
2017-08-07 21:27 ` [kernel-hardening] " Ard Biesheuvel
2017-08-07 21:27 ` Ard Biesheuvel
2017-08-07 21:44 ` Kees Cook
2017-08-07 21:44 ` Kees Cook
2017-08-07 21:46 ` Ard Biesheuvel
2017-08-07 21:46 ` Ard Biesheuvel
2017-08-07 21:47 ` Kees Cook
2017-08-07 21:47 ` Kees Cook
2017-08-07 22:00 ` [kernel-hardening] " Mark Rutland
2017-08-07 22:00 ` Mark Rutland
2017-08-07 22:00 ` Mark Rutland
2017-08-07 22:55 ` [kernel-hardening] " Laura Abbott
2017-08-07 22:55 ` Laura Abbott
2017-08-07 22:55 ` Laura Abbott
2017-08-07 23:34 ` [kernel-hardening] " Kees Cook
2017-08-07 23:34 ` Kees Cook
2017-08-07 23:34 ` Kees Cook
2017-08-08 9:23 ` Mark Rutland [this message]
2017-08-08 9:23 ` Mark Rutland
2017-08-08 9:23 ` Mark Rutland
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