From: Thomas Gleixner <tglx@linutronix.de>
To: Kees Cook <keescook@chromium.org>
Cc: linux-kernel@vger.kernel.org, Rik van Riel <riel@redhat.com>,
Casey Schaufler <casey@schaufler-ca.com>,
PaX Team <pageexec@freemail.hu>,
Brad Spengler <spender@grsecurity.net>,
Russell King <linux@armlinux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Tony Luck <tony.luck@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>,
"David S. Miller" <davem@davemloft.net>,
x86@kernel.org, Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@suse.de>,
Mathias Krause <minipli@googlemail.com>, Jan Kara <jack@suse.cz>,
Vitaly Wool <vitalywool@gmail.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Dmitry Vyukov <dvyukov@google.com>,
Laura Abbott <labbott@fedoraproject.org>,
linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org,
linux-arch@vger.kernel.org, linux-mm@kvack.org,
kernel-hardening@lists.openwall.com
Subject: Re: [PATCH 1/9] mm: Hardened usercopy
Date: Thu, 7 Jul 2016 09:42:17 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.11.1607070938430.4083@nanos> (raw)
In-Reply-To: <1467843928-29351-2-git-send-email-keescook@chromium.org>
On Wed, 6 Jul 2016, Kees Cook wrote:
> +
> +#if defined(CONFIG_FRAME_POINTER) && defined(CONFIG_X86)
> + const void *frame = NULL;
> + const void *oldframe;
> +#endif
That's ugly
> +
> + /* Object is not on the stack at all. */
> + if (obj + len <= stack || stackend <= obj)
> + return 0;
> +
> + /*
> + * Reject: object partially overlaps the stack (passing the
> + * the check above means at least one end is within the stack,
> + * so if this check fails, the other end is outside the stack).
> + */
> + if (obj < stack || stackend < obj + len)
> + return -1;
> +
> +#if defined(CONFIG_FRAME_POINTER) && defined(CONFIG_X86)
> + oldframe = __builtin_frame_address(1);
> + if (oldframe)
> + frame = __builtin_frame_address(2);
> + /*
> + * low ----------------------------------------------> high
> + * [saved bp][saved ip][args][local vars][saved bp][saved ip]
> + * ^----------------^
> + * allow copies only within here
> + */
> + while (stack <= frame && frame < stackend) {
> + /*
> + * If obj + len extends past the last frame, this
> + * check won't pass and the next frame will be 0,
> + * causing us to bail out and correctly report
> + * the copy as invalid.
> + */
> + if (obj + len <= frame)
> + return obj >= oldframe + 2 * sizeof(void *) ? 2 : -1;
> + oldframe = frame;
> + frame = *(const void * const *)frame;
> + }
> + return -1;
> +#else
> + return 1;
> +#endif
I'd rather make that a weak function returning 1 which can be replaced by
x86 for CONFIG_FRAME_POINTER=y. That also allows other architectures to
implement their specific frame checks.
Thanks,
tglx
next prev parent reply other threads:[~2016-07-07 8:10 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-06 22:25 [PATCH 0/9] mm: Hardened usercopy Kees Cook
2016-07-06 22:25 ` [PATCH 1/9] " Kees Cook
2016-07-07 5:37 ` Baruch Siach
2016-07-07 17:25 ` Kees Cook
2016-07-07 18:35 ` Baruch Siach
2016-07-07 7:42 ` Thomas Gleixner [this message]
2016-07-07 17:29 ` Kees Cook
2016-07-07 19:34 ` Thomas Gleixner
2016-07-07 8:01 ` Arnd Bergmann
2016-07-07 17:37 ` Kees Cook
2016-07-08 5:34 ` Michael Ellerman
2016-07-08 9:22 ` Arnd Bergmann
2016-07-07 16:19 ` Rik van Riel
2016-07-07 16:35 ` Rik van Riel
2016-07-07 17:41 ` Kees Cook
2016-07-06 22:25 ` [PATCH 2/9] x86/uaccess: Enable hardened usercopy Kees Cook
2016-07-06 22:25 ` [PATCH 3/9] ARM: uaccess: " Kees Cook
2016-07-06 22:25 ` [PATCH 4/9] arm64/uaccess: " Kees Cook
2016-07-07 10:07 ` Mark Rutland
2016-07-07 17:19 ` Kees Cook
2016-07-06 22:25 ` [PATCH 5/9] ia64/uaccess: " Kees Cook
2016-07-06 22:25 ` [PATCH 6/9] powerpc/uaccess: " Kees Cook
2016-07-06 22:25 ` [PATCH 7/9] sparc/uaccess: " Kees Cook
2016-07-06 22:25 ` [PATCH 8/9] mm: SLAB hardened usercopy support Kees Cook
2016-07-06 22:25 ` [PATCH 9/9] mm: SLUB " Kees Cook
2016-07-07 4:35 ` Michael Ellerman
[not found] ` <577ddc18.d351190a.1fa54.ffffbe79SMTPIN_ADDED_BROKEN@mx.google.com>
2016-07-07 18:56 ` [kernel-hardening] " Kees Cook
2016-07-08 10:19 ` Michael Ellerman
2016-07-08 13:45 ` Christoph Lameter
2016-07-08 16:07 ` Kees Cook
2016-07-08 16:20 ` Christoph Lameter
2016-07-08 17:41 ` Kees Cook
2016-07-08 20:48 ` Kees Cook
2016-07-09 5:58 ` Michael Ellerman
2016-07-09 6:07 ` Michael Ellerman
[not found] ` <57809299.84b3370a.5390c.ffff9e58SMTPIN_ADDED_BROKEN@mx.google.com>
2016-07-09 6:17 ` Valdis.Kletnieks
2016-07-09 17:07 ` Kees Cook
2016-07-11 6:08 ` Joonsoo Kim
2016-07-07 7:30 ` [PATCH 0/9] mm: Hardened usercopy Christian Borntraeger
2016-07-07 17:27 ` Kees Cook
2016-07-08 8:46 ` Ingo Molnar
2016-07-08 16:19 ` Linus Torvalds
2016-07-08 18:23 ` Ingo Molnar
2016-07-09 2:22 ` Laura Abbott
2016-07-09 2:44 ` Rik van Riel
2016-07-09 7:55 ` Ingo Molnar
2016-07-09 8:25 ` Ard Biesheuvel
2016-07-09 12:58 ` Laura Abbott
2016-07-09 17:03 ` Kees Cook
2016-07-09 17:01 ` Kees Cook
2016-07-09 21:27 ` Andy Lutomirski
2016-07-09 23:16 ` PaX Team
2016-07-10 9:16 ` Ingo Molnar
2016-07-10 12:03 ` PaX Team
2016-07-10 12:38 ` Andy Lutomirski
2016-07-11 18:40 ` Kees Cook
2016-07-11 18:34 ` Kees Cook
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