From: Will Deacon <will@kernel.org>
To: George Spelvin <lkml@sdf.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2] arm64: ptr auth: Use get_random_u64 instead of _bytes
Date: Mon, 4 May 2020 22:07:53 +0100 [thread overview]
Message-ID: <20200504210752.GB5657@willie-the-truck> (raw)
In-Reply-To: <20200428125812.GD6791@willie-the-truck>
On Tue, Apr 28, 2020 at 01:58:12PM +0100, Will Deacon wrote:
> On Tue, Mar 31, 2020 at 03:44:12PM +0000, George Spelvin wrote:
> > get_random_bytes() is approximately 4x the cost of two
> > get_random_u64() calls, because the former implements
> > anti-backtracking.
> >
> > Because these are authentication keys, useless to an attacker
> > as soon as the kernel stops using them, there is no security
> > benefit from anti-backtracking.
> >
> > Signed-off-by: George Spelvin <lkml@sdf.org>
> > Cc: Mark Rutland <mark.rutland@arm.com>
> > Cc: Will Deacon <will@kernel.org>
> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: linux-arm-kernel@lists.infradead.org
> > ---
> > v2: Took out all the clever bitmap-based stuff and made a simple
> > boring helper function to replace get_random_bytes(&key, 16).
> >
> > arch/arm64/include/asm/pointer_auth.h | 16 +++++++++++-----
> > arch/arm64/kernel/pointer_auth.c | 10 +++++-----
> > 2 files changed, 16 insertions(+), 10 deletions(-)
>
> Please can you resend this against the arm64 for-next/ptr-auth branch [1]?
> I can't apply it as-is.
Any update on this one?
Cheers,
Will
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/log/?h=for-next/ptr-auth
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prev parent reply other threads:[~2020-05-04 21:08 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-31 15:44 [PATCH v2] arm64: ptr auth: Use get_random_u64 instead of _bytes George Spelvin
2020-03-31 16:22 ` Mark Rutland
2020-04-28 12:58 ` Will Deacon
2020-05-04 21:07 ` Will Deacon [this message]
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