From: Dave Hansen <dave.hansen@intel.com>
To: Michael Sammler <msammler@mpi-sws.org>, Jann Horn <jannh@google.com>
Cc: wad@chromium.org, Kees Cook <keescook@chromium.org>,
Rik van Riel <riel@surriel.com>,
Linux API <linux-api@vger.kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
linuxram@us.ibm.com, Andy Lutomirski <luto@amacapital.net>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [RFC PATCH] seccomp: Add protection keys into seccomp_data
Date: Mon, 29 Oct 2018 10:07:09 -0700 [thread overview]
Message-ID: <9534815a-6d58-9e21-6ea5-51b9900b16e2@intel.com> (raw)
In-Reply-To: <24afa443-92e8-8202-845a-c1e1df1a3226@mpi-sws.org>
On 10/29/18 10:02 AM, Michael Sammler wrote:
>>> Also, I'm not sure the kernel provides the PKRU guarantees you want at
>>> the moment. Our implementation *probably* works, but it's mostly by
>>> accident.
> I don't know, which guarantees about the PKRU are provided at the
> moment, but the only guarantee needed for this patch is, that the kernel
> does not change the bits of the PKRU register, which belong to pkeys
> allocated by the user program, between the syscall entry and the call to
> secure_computing(). Is there are use case where the kernel would like to
> modify these bits of the PKRU?
We've been talking about doing more lax save/restore of the XSAVE
content (PKRU is part of this content). We would, for instance, only
restore it when returning to userspace, but PKRU might not be up-to-date
with the value in current->fpu.
It's not a deal-breaker with your approach, it's just something to be
careful of and make sure PKRU is up-to-date before you go use it.
next prev parent reply other threads:[~2018-10-29 17:07 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-29 11:23 [RFC PATCH] seccomp: Add protection keys into seccomp_data Michael Sammler
2018-10-29 16:25 ` Kees Cook
2018-10-29 16:37 ` Dave Hansen
2018-10-29 16:48 ` Jann Horn
2018-10-29 17:02 ` Michael Sammler
2018-10-29 17:07 ` Dave Hansen [this message]
2018-10-29 17:29 ` Dave Hansen
2018-10-29 21:55 ` Michael Sammler
2018-10-29 22:33 ` Dave Hansen
2018-10-30 10:55 ` Michael Sammler
2018-10-29 16:42 ` Jann Horn
2018-10-29 16:48 ` Ram Pai
2018-10-29 17:05 ` Michael Sammler
2022-11-14 10:09 Stephen Röttger
2022-11-15 4:16 ` Michael Sammler
2022-11-16 12:20 ` Stephen Röttger
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