From: "H. Peter Anvin" <hpa@zytor.com>
To: Kees Cook <keescook@chromium.org>, Ingo Molnar <mingo@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
Michael Ellerman <mpe@ellerman.id.au>,
Mathias Krause <minipli@googlemail.com>,
Thomas Gleixner <tglx@linutronix.de>,
x86@kernel.org, Arnd Bergmann <arnd@arndb.de>,
PaX Team <pageexec@freemail.hu>, Emese Revfy <re.emese@gmail.com>,
kernel-hardening@lists.openwall.com,
linux-kernel@vger.kernel.org,
linux-arch <linux-arch@vger.kernel.org>
Subject: Re: [PATCH v4 8/8] x86, vdso: mark vDSO read-only after init
Date: Tue, 19 Jan 2016 18:51:46 -0800 [thread overview]
Message-ID: <569EF642.90302@zytor.com> (raw)
In-Reply-To: <1453226922-16831-9-git-send-email-keescook@chromium.org>
On 01/19/16 10:08, Kees Cook wrote:
> The vDSO does not need to be writable after __init, so mark it as
> __ro_after_init. The result kills the exploit method of writing to the
> vDSO from kernel space resulting in userspace executing the modified code,
> as shown here to bypass SMEP restrictions: http://itszn.com/blog/?p=21
>
> The memory map (with added vDSO address reporting) shows the vDSO moving
> into read-only memory:
>
> Before:
> [ 0.143067] vDSO @ ffffffff82004000
> [ 0.143551] vDSO @ ffffffff82006000
> ---[ High Kernel Mapping ]---
> 0xffffffff80000000-0xffffffff81000000 16M pmd
> 0xffffffff81000000-0xffffffff81800000 8M ro PSE GLB x pmd
> 0xffffffff81800000-0xffffffff819f3000 1996K ro GLB x pte
> 0xffffffff819f3000-0xffffffff81a00000 52K ro NX pte
> 0xffffffff81a00000-0xffffffff81e00000 4M ro PSE GLB NX pmd
> 0xffffffff81e00000-0xffffffff81e05000 20K ro GLB NX pte
> 0xffffffff81e05000-0xffffffff82000000 2028K ro NX pte
> 0xffffffff82000000-0xffffffff8214f000 1340K RW GLB NX pte
> 0xffffffff8214f000-0xffffffff82281000 1224K RW NX pte
> 0xffffffff82281000-0xffffffff82400000 1532K RW GLB NX pte
> 0xffffffff82400000-0xffffffff83200000 14M RW PSE GLB NX pmd
> 0xffffffff83200000-0xffffffffc0000000 974M pmd
>
> After:
> [ 0.145062] vDSO @ ffffffff81da1000
> [ 0.146057] vDSO @ ffffffff81da4000
> ---[ High Kernel Mapping ]---
> 0xffffffff80000000-0xffffffff81000000 16M pmd
> 0xffffffff81000000-0xffffffff81800000 8M ro PSE GLB x pmd
> 0xffffffff81800000-0xffffffff819f3000 1996K ro GLB x pte
> 0xffffffff819f3000-0xffffffff81a00000 52K ro NX pte
> 0xffffffff81a00000-0xffffffff81e00000 4M ro PSE GLB NX pmd
> 0xffffffff81e00000-0xffffffff81e0b000 44K ro GLB NX pte
> 0xffffffff81e0b000-0xffffffff82000000 2004K ro NX pte
> 0xffffffff82000000-0xffffffff8214c000 1328K RW GLB NX pte
> 0xffffffff8214c000-0xffffffff8227e000 1224K RW NX pte
> 0xffffffff8227e000-0xffffffff82400000 1544K RW GLB NX pte
> 0xffffffff82400000-0xffffffff83200000 14M RW PSE GLB NX pmd
> 0xffffffff83200000-0xffffffffc0000000 974M pmd
>
> Based on work by PaX Team and Brad Spengler.
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Acked-by: Andy Lutomirski <luto@kernel.org>
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
next prev parent reply other threads:[~2016-01-20 2:51 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-19 18:08 [PATCH v4 0/8] introduce post-init read-only memory Kees Cook
2016-01-19 18:08 ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 1/8] asm-generic: consolidate mark_rodata_ro() Kees Cook
2016-01-19 18:08 ` [PATCH v4 2/8] lib: add "on" and "off" to strtobool Kees Cook
2016-01-19 18:08 ` Kees Cook
2016-01-20 2:09 ` Joe Perches
2016-01-22 23:29 ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 3/8] param: convert some "on"/"off" users " Kees Cook
2016-01-27 21:11 ` David Brown
2016-01-27 21:11 ` [kernel-hardening] " David Brown
2016-01-27 21:19 ` Kees Cook
2016-01-28 0:09 ` [PATCH] arm64: make CONFIG_DEBUG_RODATA non-optional David Brown
2016-01-28 0:09 ` David Brown
2016-01-28 0:14 ` Kees Cook
2016-01-28 0:14 ` Kees Cook
2016-01-28 8:20 ` Ard Biesheuvel
2016-01-28 8:20 ` Ard Biesheuvel
2016-01-28 11:06 ` Mark Rutland
2016-01-28 11:06 ` Mark Rutland
2016-01-28 14:06 ` Kees Cook
2016-01-28 14:06 ` Kees Cook
2016-01-28 14:59 ` Mark Rutland
2016-01-28 14:59 ` Mark Rutland
2016-01-28 15:17 ` Kees Cook
2016-01-28 15:17 ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 4/8] init: create cmdline param to disable readonly Kees Cook
2016-01-19 18:08 ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 5/8] x86: make CONFIG_DEBUG_RODATA non-optional Kees Cook
2016-01-19 18:08 ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 6/8] introduce post-init read-only memory Kees Cook
2016-01-19 18:08 ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 7/8] lkdtm: verify that __ro_after_init works correctly Kees Cook
2016-01-19 18:08 ` Kees Cook
2016-01-19 18:08 ` [PATCH v4 8/8] x86, vdso: mark vDSO read-only after init Kees Cook
2016-01-19 18:08 ` Kees Cook
2016-01-19 19:09 ` Andy Lutomirski
2016-01-20 2:51 ` H. Peter Anvin [this message]
2016-01-20 2:51 ` H. Peter Anvin
2016-01-20 2:56 ` Andy Lutomirski
2016-01-22 17:19 ` [PATCH v4 0/8] introduce post-init read-only memory David Brown
2016-01-22 17:19 ` [kernel-hardening] " David Brown
2016-01-22 19:16 ` Laura Abbott
2016-01-22 19:16 ` Laura Abbott
2016-01-22 19:57 ` Kees Cook
2016-01-23 9:49 ` Geert Uytterhoeven
2016-02-16 21:36 ` [PATCH] ARM: vdso: Mark vDSO code as read-only David Brown
2016-02-16 21:52 ` Kees Cook
2016-02-17 5:20 ` David Brown
2016-02-17 23:00 ` Kees Cook
2016-02-17 23:43 ` David Brown
2016-02-17 23:43 ` David Brown
2016-02-17 23:48 ` Kees Cook
2016-02-18 10:46 ` PaX Team
2016-02-18 10:46 ` PaX Team
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