From: Kees Cook <keescook@chromium.org>
To: Keun-O Park <kpark3469@gmail.com>
Cc: Will Deacon <will.deacon@arm.com>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
James Morse <james.morse@arm.com>,
Pratyush Anand <panand@redhat.com>,
keun-o.park@darkmatter.ae,
AKASHI Takahiro <takahiro.akashi@linaro.org>
Subject: [kernel-hardening] Re: [PATCH] arm64: usercopy: Implement stack frame object validation
Date: Mon, 30 Jan 2017 14:15:43 -0800 [thread overview]
Message-ID: <CAGXu5jJ=G05X0GBv82GrcWdVp2o5fdAqhGL3ypCL_=is=K3BLw@mail.gmail.com> (raw)
In-Reply-To: <CA+KhAHZgtTQz+ig=_G+YvasKFw6RjfMj=6EYF8sd6vs5eL1bKg@mail.gmail.com>
On Mon, Jan 30, 2017 at 3:26 AM, Keun-O Park <kpark3469@gmail.com> wrote:
> Hello Kees,
>
> Thanks for the suggestion about lkdtm. Yes, it worked correctly.
> provoke-crash# echo USERCOPY_STACK_FRAME_TO > DIRECT
> [11388.369172] lkdtm: Performing direct entry USERCOPY_STACK_FRAME_TO
> [11388.369259] lkdtm: attempting good copy_to_user of local stack
> [11388.369366] lkdtm: attempting bad copy_to_user of distant stack
> [11388.369453] usercopy: kernel memory exposure attempt detected from
> ffffffc87985fd60 (<process stack>) (32 bytes)
>
> provoke-crash# echo USERCOPY_STACK_FRAME_FROM > DIRECT
> [12687.156830] lkdtm: Performing direct entry USERCOPY_STACK_FRAME_FROM
> [12687.156918] lkdtm: attempting good copy_from_user of local stack
> [12687.156995] lkdtm: attempting bad copy_from_user of distant stack
> [12687.157082] usercopy: kernel memory overwrite attempt detected to
> ffffffc87985fd60 (<process stack>) (32 bytes)
>
> One thing I want to ask is..
> Does USERCOPY_HEAP_FLAG_FROM/TO work correctly in latest kernel?
No, this protection (the whitelisting flag) isn't implemented yet in
upstream. (You're more than welcome to dig into it, if you want!)
> Both on Pixel(v3.18) and on emulator(v4.10-rc5)
> In these two cases the bad attempt passed. I guess the code for this
> test might not be ready. Am I right?
Correct.
-Kees
--
Kees Cook
Pixel Security
next prev parent reply other threads:[~2017-01-30 22:15 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-25 13:46 [kernel-hardening] [PATCH] arm64: usercopy: Implement stack frame object validation kpark3469
2017-01-25 13:54 ` [kernel-hardening] " Will Deacon
2017-01-25 14:44 ` Keun-O Park
2017-01-26 0:58 ` Kees Cook
2017-01-30 11:26 ` Keun-O Park
2017-01-30 22:15 ` Kees Cook [this message]
2017-01-26 7:10 ` AKASHI Takahiro
2017-01-30 12:42 ` Keun-O Park
2017-01-30 22:19 ` Kees Cook
2017-01-31 9:10 ` Keun-O Park
2017-01-31 17:56 ` Kees Cook
2017-01-26 16:40 ` Yann Droneaud
2017-01-26 17:36 ` Kees Cook
2017-01-26 17:47 ` Will Deacon
2017-01-26 15:23 ` James Morse
2017-02-02 13:34 ` Keun-O Park
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