linux-kernel - Re: [PATCH v2 00/11] test_user

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Date:	Fri, 7 Aug 2015 16:51:17 -0700
From:	Kees Cook <keescook@...omium.org>
To:	James Hogan <james.hogan@...tec.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	linux-arch <linux-arch@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Michal Simek <monstr@...str.eu>,
	Ley Foon Tan <lftan@...era.com>,
	Jonas Bonn <jonas@...thpole.se>,
	Chris Zankel <chris@...kel.net>,
	Max Filippov <jcmvbkbc@...il.com>,
	nios2-dev@...ts.rocketboards.org, linux@...ts.openrisc.net,
	linux-xtensa@...ux-xtensa.org
Subject: Re: [PATCH v2 00/11] test_user_copy improvements

On Fri, Aug 7, 2015 at 8:21 AM, James Hogan <james.hogan@...tec.com> wrote:
> These patches extend the test_user_copy test module to handle lots more
> cases of user accessors which architectures can override separately, and
> in particular those which are important for checking the MIPS Enhanced
> Virtual Addressing (EVA) implementations, which need to handle
> overlapping user and kernel address spaces, with special instructions
> for accessing user address space from kernel mode.
>
> - Checking that kernel pointers are accepted when user address limit is
>   set to KERNEL_DS, as done by the kernel when it internally invokes
>   system calls with kernel pointers.
> - Checking of the unchecked accessors (which don't call access_ok()).
>   Some of the tests are special cased for EVA at the moment which has
>   stricter hardware guarantees for bad user accesses than other
>   configurations.
> - Checking of other sets of user accessors, including the inatomic user
>   copies, clear_user, compatibility accessors (copy_in_user and
>   _unaligned), the user string accessors, and the user checksum
>   functions, all of which need special handling in arch code with EVA.
>
> Tested on MIPS with and without EVA, and on x86_64.
>
> Only build tested for arm, blackfin, metag, microblaze, openrisc,
> parisc, powerpc, sh, sparc, tile, i386 & xtensa.
>
> All arches were audited for the appropriate exports, only score is known
> to still be missing some.
>
> Changes in v2:
> - Add arch exports (patches 1-4).
> - Reorder patches slightly.
> - Patch 9: Drop strlen_user test. Microblaze doesn't define it, and
>   nothing actually uses it. IMO it should be removed, and there's no
>   point testing it in the mean time.
> - Patch 10: Conditionalise on CONFIG_COMPAT, otherwise it breaks build
>   on some 32-bit arches e.g. i386 (kbuild test robot).
> - Patch 10: Add testing of _unaligned accessors, which are also
>   conditional upon CONFIG_COMPAT.
> - Patch 11: Only test csum_partial_copy_from_user #ifndef
>   _HAVE_ARCH_COPY_AND_CSUM_FROM_USER, fixing powerpc64 build (Stephen
>   Rothwell)

Thanks for the fixes!

Acked-by: Kees Cook <keescook@...omium.org>

-Kees

>
> James Hogan (11):
>   microblaze: Export __strnlen_user to modules
>   nios2: Export strncpy_from_user / strnlen_user to modules
>   openrisc: Export __clear_user to modules
>   xtensa: Export __strnlen_user to modules
>   test_user_copy: Check legit kernel accesses
>   test_user_copy: Check unchecked accessors
>   test_user_copy: Check __copy_{to,from}_user_inatomic()
>   test_user_copy: Check __clear_user()/clear_user()
>   test_user_copy: Check user string accessors
>   test_user_copy: Check user compatibility accessors
>   test_user_copy: Check user checksum functions
>
>  arch/microblaze/kernel/microblaze_ksyms.c |   1 +
>  arch/nios2/mm/uaccess.c                   |   2 +
>  arch/openrisc/kernel/or32_ksyms.c         |   1 +
>  arch/xtensa/kernel/xtensa_ksyms.c         |   1 +
>  lib/test_user_copy.c                      | 251 ++++++++++++++++++++++++++++++
>  5 files changed, 256 insertions(+)
>
> Cc: Kees Cook <keescook@...omium.org>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Michal Simek <monstr@...str.eu>
> Cc: Ley Foon Tan <lftan@...era.com>
> Cc: Jonas Bonn <jonas@...thpole.se>
> Cc: Chris Zankel <chris@...kel.net>
> Cc: Max Filippov <jcmvbkbc@...il.com>
> Cc: nios2-dev@...ts.rocketboards.org
> Cc: linux@...ts.openrisc.net
> Cc: linux-xtensa@...ux-xtensa.org
> --
> 2.3.6
>



-- 
Kees Cook
Chrome OS Security
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