From: Mike Rapoport <rppt@linux.ibm.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Alexandre Chartre <alexandre.chartre@oracle.com>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
James Bottomley <James.Bottomley@hansenpartnership.com>,
Jonathan Adams <jwadams@google.com>,
Kees Cook <keescook@chromium.org>, Paul Turner <pjt@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Linux-MM <linux-mm@kvack.org>,
LSM List <linux-security-module@vger.kernel.org>,
X86 ML <x86@kernel.org>
Subject: Re: [RFC PATCH 5/7] x86/mm/fault: hook up SCI verification
Date: Wed, 1 May 2019 08:39:59 +0300 [thread overview]
Message-ID: <20190501053958.GA3877@rapoport-lnx> (raw)
In-Reply-To: <CALCETrWrtRo1PqdVmJQQ95J8ORy9WBkUraJCqL6JNmmAkw=H0w@mail.gmail.com>
On Tue, Apr 30, 2019 at 09:44:09AM -0700, Andy Lutomirski wrote:
> On Sat, Apr 27, 2019 at 10:47 PM Mike Rapoport <rppt@linux.ibm.com> wrote:
> >
> > On Fri, Apr 26, 2019 at 09:42:23AM +0200, Peter Zijlstra wrote:
> > > On Fri, Apr 26, 2019 at 12:45:52AM +0300, Mike Rapoport wrote:
> > > > If a system call runs in isolated context, it's accesses to kernel code and
> > > > data will be verified by SCI susbsytem.
> > > >
> > > > Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> > > > ---
> > > > arch/x86/mm/fault.c | 28 ++++++++++++++++++++++++++++
> > > > 1 file changed, 28 insertions(+)
> > >
> > > There's a distinct lack of touching do_double_fault(). It appears to me
> > > that you'll instantly trigger #DF when you #PF, because the #PF handler
> > > itself will not be able to run.
> >
> > The #PF handler is able to run. On interrupt/error entry the cr3 is
> > switched to the full kernel page tables, pretty much like PTI does for
> > user <-> kernel transitions. It's in the patch 3.
> >
> >
>
> PeterZ meant page_fault, not do_page_fault. In your patch, page_fault
> and some of error_entry run before that magic switchover happens. If
> they're not in the page tables, you double-fault.
The entry code is in sci page tables, just like in user-space page tables
with PTI.
> And don't even try to do SCI magic in the double-fault handler. As I
> understand it, the SDM and APM aren't kidding when they say that #DF
> is an abort, not a fault. There is a single case in the kernel where
> we recover from #DF, and it was vetted by microcode people.
>
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2019-05-01 5:40 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-25 21:45 [RFC PATCH 0/7] x86: introduce system calls addess space isolation Mike Rapoport
2019-04-25 21:45 ` [RFC PATCH 1/7] x86/cpufeatures: add X86_FEATURE_SCI Mike Rapoport
2019-04-25 21:45 ` [RFC PATCH 2/7] x86/sci: add core implementation for system call isolation Mike Rapoport
2019-04-26 7:49 ` Peter Zijlstra
2019-04-28 5:45 ` Mike Rapoport
2019-04-26 8:31 ` Ingo Molnar
2019-04-26 9:58 ` Ingo Molnar
2019-04-26 21:26 ` Andy Lutomirski
2019-04-27 8:47 ` Ingo Molnar
2019-04-27 10:46 ` Ingo Molnar
2019-04-29 18:26 ` James Morris
2019-04-29 18:43 ` Andy Lutomirski
2019-04-29 18:46 ` Andy Lutomirski
2019-04-30 5:03 ` Ingo Molnar
2019-04-30 9:38 ` Peter Zijlstra
2019-04-30 11:05 ` Ingo Molnar
2019-05-02 11:35 ` Robert O'Callahan
2019-05-02 15:20 ` Ingo Molnar
2019-05-02 21:07 ` Robert O'Callahan
2019-04-26 14:44 ` James Bottomley
2019-04-26 14:46 ` Dave Hansen
2019-04-26 14:57 ` James Bottomley
2019-04-26 15:07 ` Andy Lutomirski
2019-04-26 15:19 ` James Bottomley
2019-04-26 17:40 ` Andy Lutomirski
2019-04-26 18:49 ` James Bottomley
2019-04-26 19:22 ` Andy Lutomirski
2019-04-25 21:45 ` [RFC PATCH 3/7] x86/entry/64: add infrastructure for switching to isolated syscall context Mike Rapoport
2019-04-25 21:45 ` [RFC PATCH 4/7] x86/sci: hook up isolated system call entry and exit Mike Rapoport
2019-04-25 21:45 ` [RFC PATCH 5/7] x86/mm/fault: hook up SCI verification Mike Rapoport
2019-04-26 7:42 ` Peter Zijlstra
2019-04-28 5:47 ` Mike Rapoport
2019-04-30 16:44 ` Andy Lutomirski
2019-05-01 5:39 ` Mike Rapoport [this message]
2019-04-25 21:45 ` [RFC PATCH 6/7] security: enable system call isolation in kernel config Mike Rapoport
2019-04-25 21:45 ` [RFC PATCH 7/7] sci: add example system calls to exercse SCI Mike Rapoport
2019-04-26 0:30 ` [RFC PATCH 0/7] x86: introduce system calls addess space isolation Andy Lutomirski
2019-04-26 8:07 ` Jiri Kosina
2019-04-28 6:01 ` Mike Rapoport
2019-04-26 14:41 ` Dave Hansen
2019-04-28 6:08 ` Mike Rapoport
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