From: Khalid Aziz <khalid.aziz@oracle.com>
To: Kees Cook <keescook@google.com>, Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Nadav Amit <nadav.amit@gmail.com>, Ingo Molnar <mingo@kernel.org>,
Juerg Haefliger <juergh@gmail.com>,
Tycho Andersen <tycho@tycho.ws>,
Julian Stecklina <jsteckli@amazon.de>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Juerg Haefliger <juerg.haefliger@canonical.com>,
deepa.srinivasan@oracle.com, chris hyser <chris.hyser@oracle.com>,
Tyler Hicks <tyhicks@canonical.com>,
David Woodhouse <dwmw@amazon.co.uk>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Jon Masters <jcm@redhat.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
iommu <iommu@lists.linux-foundation.org>, X86 ML <x86@kernel.org>,
"linux-alpha@vger.kernel.org"
<linux-arm-kernel@lists.infradead.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
LSM List <linux-security-module@vger.kernel.org>,
Khalid Aziz <khalid@gonehiking.org>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Dave Hansen <dave@sr71.net>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Arjan van de Ven <arjan@infradead.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [RFC PATCH v9 03/13] mm: Add support for eXclusive Page Frame Ownership (XPFO)
Date: Thu, 18 Apr 2019 08:34:32 -0600 [thread overview]
Message-ID: <8f9d059d-e720-cd24-faa6-45493fc012e0@oracle.com> (raw)
In-Reply-To: <CAGXu5jL-qJtW7eH8S2yhqciE+J+FWz8HHzTrGJTgVUbd55n6dQ@mail.gmail.com>
On 4/17/19 11:41 PM, Kees Cook wrote:
> On Wed, Apr 17, 2019 at 11:41 PM Andy Lutomirski <luto@kernel.org> wrote:
>> I don't think this type of NX goof was ever the argument for XPFO.
>> The main argument I've heard is that a malicious user program writes a
>> ROP payload into user memory (regular anonymous user memory) and then
>> gets the kernel to erroneously set RSP (*not* RIP) to point there.
>
> Well, more than just ROP. Any of the various attack primitives. The NX
> stuff is about moving RIP: SMEP-bypassing. But there is still basic
> SMAP-bypassing for putting a malicious structure in userspace and
> having the kernel access it via the linear mapping, etc.
>
>> I find this argument fairly weak for a couple reasons. First, if
>> we're worried about this, let's do in-kernel CFI, not XPFO, to
>
> CFI is getting much closer. Getting the kernel happy under Clang, LTO,
> and CFI is under active development. (It's functional for arm64
> already, and pieces have been getting upstreamed.)
>
CFI theoretically offers protection with fairly low overhead. I have not
played much with CFI in clang. I agree with Linus that probability of
bugs in XPFO implementation itself is a cause of concern. If CFI in
Clang can provide us the same level of protection as XPFO does, I
wouldn't want to push for an expensive change like XPFO.
If Clang/CFI can't get us there for extended period of time, does it
make sense to continue to poke at XPFO?
Thanks,
Khalid
next prev parent reply other threads:[~2019-04-18 14:36 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1554248001.git.khalid.aziz@oracle.com>
2019-04-04 16:44 ` [RFC PATCH v9 00/13] Add support for eXclusive Page Frame Ownership Nadav Amit
2019-04-04 17:18 ` Khalid Aziz
[not found] ` <f1ac3700970365fb979533294774af0b0dd84b3b.1554248002.git.khalid.aziz@oracle.com>
2019-04-17 16:15 ` [RFC PATCH v9 03/13] mm: Add support for eXclusive Page Frame Ownership (XPFO) Ingo Molnar
2019-04-17 16:49 ` Khalid Aziz
2019-04-17 17:09 ` Ingo Molnar
2019-04-17 17:19 ` Nadav Amit
2019-04-17 17:26 ` Ingo Molnar
2019-04-17 17:44 ` Nadav Amit
2019-04-17 21:19 ` Thomas Gleixner
[not found] ` <CAHk-=wgBMg9P-nYQR2pS0XwVdikPCBqLsMFqR9nk=wSmAd4_5g@mail.gmail.com>
2019-04-17 23:42 ` Thomas Gleixner
2019-04-17 23:52 ` Linus Torvalds
2019-04-18 4:41 ` Andy Lutomirski
2019-04-18 5:41 ` Kees Cook
2019-04-18 14:34 ` Khalid Aziz [this message]
2019-04-22 19:30 ` Khalid Aziz
2019-04-22 22:23 ` Kees Cook
2019-04-18 6:14 ` Thomas Gleixner
2019-04-17 17:33 ` Khalid Aziz
2019-04-17 19:49 ` Andy Lutomirski
2019-04-17 19:52 ` Tycho Andersen
2019-04-17 20:12 ` Khalid Aziz
2019-05-01 14:49 ` Waiman Long
2019-05-01 15:18 ` Khalid Aziz
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