From: Khalid Aziz <khalid.aziz-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
To: Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Dave Hansen <dave-gkUM19QKKo4@public.gmane.org>,
linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
deepa.srinivasan-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org,
"H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>,
Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>,
tycho-E0fblnxP3wo@public.gmane.org,
x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
jsteckli-ebkRAfMGSJGzQB+pC5nmwQ@public.gmane.org,
Arjan van de Ven <arjan-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
Peter Zijlstra
<a.p.zijlstra-/NLkJaSkS4VmR6Xm/wNWPw@public.gmane.org>,
konrad.wilk-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org,
jcm-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
Greg Kroah-Hartman
<gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>,
Borislav Petkov <bp-Gina5bIWoIWzQB+pC5nmwQ@public.gmane.org>,
Andy Lutomirski <luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
boris.ostrovsky-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org,
chris.hyser-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
Khalid Aziz <khalid-21RPF02GE+GXwddmVfQv5g@public.gmane.org>,
juergh-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
andrew.cooper3-Sxgqhf6Nn4DQT0dZR+AlfA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
tyhicks-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org,
linux-security-module-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Juerg Haefliger
<juerg.haefliger-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>,
keescook-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org,
Andrew Morton
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
Linu
Subject: Re: [RFC PATCH v9 03/13] mm: Add support for eXclusive Page Frame Ownership (XPFO)
Date: Wed, 17 Apr 2019 10:49:26 -0600 [thread overview]
Message-ID: <e16c1d73-d361-d9c7-5b8e-c495318c2509@oracle.com> (raw)
In-Reply-To: <20190417161042.GA43453-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
On 4/17/19 10:15 AM, Ingo Molnar wrote:
>
> [ Sorry, had to trim the Cc: list from hell. Tried to keep all the
> mailing lists and all x86 developers. ]
>
> * Khalid Aziz <khalid.aziz-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> wrote:
>
>> From: Juerg Haefliger <juerg.haefliger-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>
>>
>> This patch adds basic support infrastructure for XPFO which protects
>> against 'ret2dir' kernel attacks. The basic idea is to enforce
>> exclusive ownership of page frames by either the kernel or userspace,
>> unless explicitly requested by the kernel. Whenever a page destined for
>> userspace is allocated, it is unmapped from physmap (the kernel's page
>> table). When such a page is reclaimed from userspace, it is mapped back
>> to physmap. Individual architectures can enable full XPFO support using
>> this infrastructure by supplying architecture specific pieces.
>
> I have a higher level, meta question:
>
> Is there any updated analysis outlining why this XPFO overhead would be
> required on x86-64 kernels running on SMAP/SMEP CPUs which should be all
> recent Intel and AMD CPUs, and with kernel that mark all direct kernel
> mappings as non-executable - which should be all reasonably modern
> kernels later than v4.0 or so?
>
> I.e. the original motivation of the XPFO patches was to prevent execution
> of direct kernel mappings. Is this motivation still present if those
> mappings are non-executable?
>
> (Sorry if this has been asked and answered in previous discussions.)
Hi Ingo,
That is a good question. Because of the cost of XPFO, we have to be very
sure we need this protection. The paper from Vasileios, Michalis and
Angelos - <http://www.cs.columbia.edu/~vpk/papers/ret2dir.sec14.pdf>,
does go into how ret2dir attacks can bypass SMAP/SMEP in sections 6.1
and 6.2.
Thanks,
Khalid
WARNING: multiple messages have this Message-ID (diff)
From: Khalid Aziz <khalid.aziz@oracle.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Dave Hansen <dave@sr71.net>,
linux-doc@vger.kernel.org, linux-mm@kvack.org,
deepa.srinivasan@oracle.com, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
tycho@tycho.ws, x86@kernel.org, iommu@lists.linux-foundation.org,
jsteckli@amazon.de, Arjan van de Ven <arjan@infradead.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
konrad.wilk@oracle.com, jcm@redhat.com,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
boris.ostrovsky@oracle.com, chris.hyser@oracle.com,
linux-arm-kernel@lists.infradead.org,
Khalid Aziz <khalid@gonehiking.org>,
juergh@gmail.com, andrew.cooper3@citrix.com,
linux-kernel@vger.kernel.org, tyhicks@canonical.com,
linux-security-module@vger.kernel.org,
Juerg Haefliger <juerg.haefliger@canonical.com>,
keescook@google.com, Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
dwmw@amazon.co.uk
Subject: Re: [RFC PATCH v9 03/13] mm: Add support for eXclusive Page Frame Ownership (XPFO)
Date: Wed, 17 Apr 2019 10:49:26 -0600 [thread overview]
Message-ID: <e16c1d73-d361-d9c7-5b8e-c495318c2509@oracle.com> (raw)
Message-ID: <20190417164926.uqHg84r_MHxdVlA95-Bsbyts9zgAlNQKhTwScXx4zPs@z> (raw)
In-Reply-To: <20190417161042.GA43453@gmail.com>
On 4/17/19 10:15 AM, Ingo Molnar wrote:
>
> [ Sorry, had to trim the Cc: list from hell. Tried to keep all the
> mailing lists and all x86 developers. ]
>
> * Khalid Aziz <khalid.aziz@oracle.com> wrote:
>
>> From: Juerg Haefliger <juerg.haefliger@canonical.com>
>>
>> This patch adds basic support infrastructure for XPFO which protects
>> against 'ret2dir' kernel attacks. The basic idea is to enforce
>> exclusive ownership of page frames by either the kernel or userspace,
>> unless explicitly requested by the kernel. Whenever a page destined for
>> userspace is allocated, it is unmapped from physmap (the kernel's page
>> table). When such a page is reclaimed from userspace, it is mapped back
>> to physmap. Individual architectures can enable full XPFO support using
>> this infrastructure by supplying architecture specific pieces.
>
> I have a higher level, meta question:
>
> Is there any updated analysis outlining why this XPFO overhead would be
> required on x86-64 kernels running on SMAP/SMEP CPUs which should be all
> recent Intel and AMD CPUs, and with kernel that mark all direct kernel
> mappings as non-executable - which should be all reasonably modern
> kernels later than v4.0 or so?
>
> I.e. the original motivation of the XPFO patches was to prevent execution
> of direct kernel mappings. Is this motivation still present if those
> mappings are non-executable?
>
> (Sorry if this has been asked and answered in previous discussions.)
Hi Ingo,
That is a good question. Because of the cost of XPFO, we have to be very
sure we need this protection. The paper from Vasileios, Michalis and
Angelos - <http://www.cs.columbia.edu/~vpk/papers/ret2dir.sec14.pdf>,
does go into how ret2dir attacks can bypass SMAP/SMEP in sections 6.1
and 6.2.
Thanks,
Khalid
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2019-04-17 16:49 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-03 17:34 [RFC PATCH v9 00/13] Add support for eXclusive Page Frame Ownership Khalid Aziz
2019-04-03 17:34 ` [RFC PATCH v9 11/13] xpfo, mm: optimize spinlock usage in xpfo_kunmap Khalid Aziz
[not found] ` <5bab13e12d4215112ad2180106cc6bb9b513754a.1554248002.git.khalid.aziz-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2019-04-04 7:56 ` Peter Zijlstra
2019-04-04 16:06 ` Khalid Aziz
[not found] ` <cover.1554248001.git.khalid.aziz-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2019-04-03 17:34 ` [RFC PATCH v9 01/13] mm: add MAP_HUGETLB support to vm_mmap Khalid Aziz
2019-04-03 17:34 ` [RFC PATCH v9 02/13] x86: always set IF before oopsing from page fault Khalid Aziz
[not found] ` <e6c57f675e5b53d4de266412aa526b7660c47918.1554248002.git.khalid.aziz-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2019-04-04 0:12 ` Andy Lutomirski
[not found] ` <CALCETrXvwuwkVSJ+S5s7wTBkNNj3fRVxpx9BvsXWrT=3ZdRnCw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2019-04-04 1:42 ` Tycho Andersen
2019-04-04 4:12 ` Andy Lutomirski
[not found] ` <CALCETrVp37Xo3EMHkeedP1zxUMf9og=mceBa8c55e1F4G1DRSQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2019-04-04 15:47 ` Tycho Andersen
2019-04-04 16:23 ` Sebastian Andrzej Siewior
2019-04-04 16:28 ` Thomas Gleixner
[not found] ` <alpine.DEB.2.21.1904041822320.1802-ecDvlHI5BZPZikZi3RtOZ1XZhhPuCNm+@public.gmane.org>
2019-04-04 17:11 ` Andy Lutomirski
2019-04-03 17:34 ` [RFC PATCH v9 03/13] mm: Add support for eXclusive Page Frame Ownership (XPFO) Khalid Aziz
[not found] ` <f1ac3700970365fb979533294774af0b0dd84b3b.1554248002.git.khalid.aziz-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2019-04-04 7:21 ` Peter Zijlstra
[not found] ` <20190404072152.GN4038-Nxj+rRp3nVydTX5a5knrm8zTDFooKrT+cvkQGrU6aU0@public.gmane.org>
2019-04-04 9:25 ` Peter Zijlstra
2019-04-04 14:48 ` Tycho Andersen
2019-04-04 7:43 ` Peter Zijlstra
[not found] ` <20190404074323.GO4038-Nxj+rRp3nVydTX5a5knrm8zTDFooKrT+cvkQGrU6aU0@public.gmane.org>
2019-04-04 15:15 ` Khalid Aziz
[not found] ` <b414bacc-2883-1914-38ec-3d8f4a032e10-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2019-04-04 17:01 ` Peter Zijlstra
2019-04-17 16:15 ` Ingo Molnar
2019-04-17 16:15 ` Ingo Molnar
[not found] ` <20190417161042.GA43453-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2019-04-17 16:49 ` Khalid Aziz [this message]
2019-04-17 16:49 ` Khalid Aziz
2019-04-17 17:09 ` Ingo Molnar
2019-04-17 17:09 ` Ingo Molnar
2019-04-17 17:19 ` Nadav Amit
2019-04-17 17:19 ` Nadav Amit
2019-04-17 17:26 ` Ingo Molnar
2019-04-17 17:26 ` Ingo Molnar
2019-04-17 17:44 ` Nadav Amit
2019-04-17 17:44 ` Nadav Amit
2019-04-17 21:19 ` Thomas Gleixner
2019-04-17 21:19 ` Thomas Gleixner
[not found] ` <alpine.DEB.2.21.1904172317460.3174-ecDvlHI5BZPZikZi3RtOZ1XZhhPuCNm+@public.gmane.org>
2019-04-17 23:18 ` Linus Torvalds
2019-04-17 23:18 ` Linus Torvalds
2019-04-17 23:42 ` Thomas Gleixner
2019-04-17 23:42 ` Thomas Gleixner
2019-04-17 23:52 ` Linus Torvalds
2019-04-17 23:52 ` Linus Torvalds
2019-04-18 4:41 ` Andy Lutomirski
2019-04-18 4:41 ` Andy Lutomirski
2019-04-18 5:41 ` Kees Cook
2019-04-18 5:41 ` Kees Cook via iommu
2019-04-18 14:34 ` Khalid Aziz
2019-04-18 14:34 ` Khalid Aziz
2019-04-22 19:30 ` Khalid Aziz
2019-04-22 19:30 ` Khalid Aziz
[not found] ` <8f9d059d-e720-cd24-faa6-45493fc012e0-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2019-04-22 22:23 ` Kees Cook via iommu
2019-04-22 22:23 ` Kees Cook via iommu
[not found] ` <CAHk-=whUwOjFW6RjHVM8kNOv1QVLJuHj2Dda0=mpLPdJ1UyatQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2019-04-18 6:14 ` Thomas Gleixner
2019-04-18 6:14 ` Thomas Gleixner
2019-04-17 17:33 ` Khalid Aziz
2019-04-17 17:33 ` Khalid Aziz
2019-04-17 19:49 ` Andy Lutomirski
2019-04-17 19:49 ` Andy Lutomirski
[not found] ` <CALCETrXFzWFMrV-zDa4QFjB=4WnC9RZmorBko65dLGhymDpeQw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2019-04-17 19:52 ` Tycho Andersen
2019-04-17 19:52 ` Tycho Andersen
2019-04-17 20:12 ` Khalid Aziz
2019-04-17 20:12 ` Khalid Aziz
2019-05-01 14:49 ` Waiman Long
2019-05-01 14:49 ` Waiman Long
2019-05-01 15:18 ` Khalid Aziz
2019-05-01 15:18 ` Khalid Aziz
2019-04-03 17:34 ` [RFC PATCH v9 04/13] xpfo, x86: Add support for XPFO for x86-64 Khalid Aziz
[not found] ` <c15e7d09dfe3dfdb9947d39ed0ddd6573ff86dbf.1554248002.git.khalid.aziz-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2019-04-04 7:52 ` Peter Zijlstra
[not found] ` <20190404075206.GP4038-Nxj+rRp3nVydTX5a5knrm8zTDFooKrT+cvkQGrU6aU0@public.gmane.org>
2019-04-04 15:40 ` Khalid Aziz
2019-04-03 17:34 ` [RFC PATCH v9 05/13] mm: add a user_virt_to_phys symbol Khalid Aziz
2019-04-03 17:34 ` [RFC PATCH v9 06/13] lkdtm: Add test for XPFO Khalid Aziz
2019-04-03 17:34 ` [RFC PATCH v9 07/13] arm64/mm: Add support " Khalid Aziz
2019-04-03 17:34 ` [RFC PATCH v9 08/13] swiotlb: Map the buffer if it was unmapped by XPFO Khalid Aziz
2019-04-03 17:34 ` [RFC PATCH v9 09/13] xpfo: add primitives for mapping underlying memory Khalid Aziz
2019-04-03 17:34 ` [RFC PATCH v9 10/13] arm64/mm, xpfo: temporarily map dcache regions Khalid Aziz
2019-04-03 17:34 ` [RFC PATCH v9 12/13] xpfo, mm: Defer TLB flushes for non-current CPUs (x86 only) Khalid Aziz
[not found] ` <4495dda4bfc4a06b3312cc4063915b306ecfaecb.1554248002.git.khalid.aziz-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2019-04-04 4:10 ` Andy Lutomirski
[not found] ` <CALCETrXMXxnWqN94d83UvGWhkD1BNWiwvH2vsUth1w0T3=0ywQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2019-04-04 22:55 ` Khalid Aziz
[not found] ` <91f1dbce-332e-25d1-15f6-0e9cfc8b797b-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2019-04-05 7:17 ` Thomas Gleixner
[not found] ` <alpine.DEB.2.21.1904050909520.1802-ecDvlHI5BZPZikZi3RtOZ1XZhhPuCNm+@public.gmane.org>
2019-04-05 14:44 ` Dave Hansen
[not found] ` <26b00051-b03c-9fce-1446-52f0d6ed52f8-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2019-04-05 15:24 ` Andy Lutomirski
2019-04-05 15:24 ` Andy Lutomirski
[not found] ` <DFA69954-3F0F-4B79-A9B5-893D33D87E51-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
2019-04-05 15:56 ` Tycho Andersen
2019-04-05 15:56 ` Tycho Andersen
2019-04-05 16:32 ` Andy Lutomirski
2019-04-05 16:32 ` Andy Lutomirski
2019-04-05 15:56 ` Khalid Aziz
2019-04-05 15:56 ` Khalid Aziz
2019-04-05 16:01 ` Dave Hansen
2019-04-05 16:01 ` Dave Hansen
[not found] ` <36b999d4-adf6-08a3-2897-d77b9cba20f8-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2019-04-05 16:27 ` Andy Lutomirski
2019-04-05 16:27 ` Andy Lutomirski
[not found] ` <E0BBD625-6FE0-4A8A-884B-E10FAFC3319E-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
2019-04-05 16:41 ` Peter Zijlstra
2019-04-05 16:41 ` Peter Zijlstra
2019-04-05 17:35 ` Khalid Aziz
2019-04-05 17:35 ` Khalid Aziz
2019-04-05 15:44 ` Khalid Aziz
2019-04-05 15:44 ` Khalid Aziz
2019-04-05 15:24 ` Andy Lutomirski
2019-04-05 15:24 ` Andy Lutomirski
2019-04-04 8:18 ` Peter Zijlstra
2019-04-03 17:34 ` [RFC PATCH v9 13/13] xpfo, mm: Optimize XPFO TLB flushes by batching them together Khalid Aziz
2019-04-06 6:40 ` [RFC PATCH v9 00/13] Add support for eXclusive Page Frame Ownership Jon Masters
2019-04-06 6:40 ` Jon Masters
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