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[PATCH v2 14/36] x86/entry/64/compat: Disable SYSENTER and SYSCALL32 entries

Started byAndy Lutomirski <luto@kernel.org>
First post2015-10-06 03:00 +0200
Last post2015-10-09 15:10 +0200
Articles 4 — 4 participants

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  [PATCH v2 14/36] x86/entry/64/compat: Disable SYSENTER and SYSCALL32 entries Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
    Re: [PATCH v2 14/36] x86/entry/64/compat: Disable SYSENTER and  SYSCALL32 entries Borislav Petkov <bp@alien8.de> - 2015-10-08 17:50 +0200
      Re: [PATCH v2 14/36] x86/entry/64/compat: Disable SYSENTER and  SYSCALL32 entries Andy Lutomirski <luto@amacapital.net> - 2015-10-09 21:20 +0200
    [tip:x86/asm] x86/entry/64/compat:   Disable SYSENTER and SYSCALL32 entries tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:10 +0200

#1240077 — [PATCH v2 14/36] x86/entry/64/compat: Disable SYSENTER and SYSCALL32 entries

FromAndy Lutomirski <luto@kernel.org>
Date2015-10-06 03:00 +0200
Subject[PATCH v2 14/36] x86/entry/64/compat: Disable SYSENTER and SYSCALL32 entries
Message-ID<qgoLN-7cw-25@gated-at.bofh.it>
We've disabled the vDSO helpers to call them, so turn off the
entries entirely (temporarily) in preparation for cleaning them up.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 arch/x86/entry/entry_64_compat.S | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index 1432d60a1f4a..e11aa38696fe 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -103,6 +103,14 @@ ENTRY(entry_SYSENTER_compat)
 	jnz	sysenter_fix_flags
 sysenter_flags_fixed:
 
+	/* Temporary: SYSENTER is disabled. */
+#ifdef CONFIG_CONTEXT_TRACKING
+	call enter_from_user_mode
+#endif
+	ENABLE_INTERRUPTS(CLBR_NONE)
+	movl $11, %edi
+	call do_exit
+
 	/*
 	 * Re-enable interrupts.  IRQ tracing already thinks that IRQs are
 	 * on (since we treat user mode as having IRQs on), and the
@@ -324,6 +332,11 @@ ENTRY(entry_SYSCALL_compat)
 	 * it is too small to ever cause noticeable irq latency.
 	 */
 	SWAPGS_UNSAFE_STACK
+
+	/* Temporary: SYSCALL32 is disabled. */
+	movl	$-ENOSYS, %eax
+	USERGS_SYSRET32
+
 	movl	%esp, %r8d
 	movq	PER_CPU_VAR(cpu_current_top_of_stack), %rsp
 	ENABLE_INTERRUPTS(CLBR_NONE)
-- 
2.4.3

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#1242550 — Re: [PATCH v2 14/36] x86/entry/64/compat: Disable SYSENTER and SYSCALL32 entries

FromBorislav Petkov <bp@alien8.de>
Date2015-10-08 17:50 +0200
SubjectRe: [PATCH v2 14/36] x86/entry/64/compat: Disable SYSENTER and SYSCALL32 entries
Message-ID<qhlCa-7Qf-13@gated-at.bofh.it>
In reply to#1240077
On Mon, Oct 05, 2015 at 05:48:02PM -0700, Andy Lutomirski wrote:
> We've disabled the vDSO helpers to call them, so turn off the
> entries entirely (temporarily) in preparation for cleaning them up.
> 
> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> ---
>  arch/x86/entry/entry_64_compat.S | 13 +++++++++++++
>  1 file changed, 13 insertions(+)

What do we say for the case when someone bisects, lands at this patch
and, as Murphy would generally do it, has a reproducer which is calling
SYSENTER/SYSCALL32?

Tough luck?

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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#1243616 — Re: [PATCH v2 14/36] x86/entry/64/compat: Disable SYSENTER and SYSCALL32 entries

FromAndy Lutomirski <luto@amacapital.net>
Date2015-10-09 21:20 +0200
SubjectRe: [PATCH v2 14/36] x86/entry/64/compat: Disable SYSENTER and SYSCALL32 entries
Message-ID<qhLmV-2PX-15@gated-at.bofh.it>
In reply to#1242550
On Oct 8, 2015 8:40 AM, "Borislav Petkov" <bp@alien8.de> wrote:
>
> On Mon, Oct 05, 2015 at 05:48:02PM -0700, Andy Lutomirski wrote:
> > We've disabled the vDSO helpers to call them, so turn off the
> > entries entirely (temporarily) in preparation for cleaning them up.
> >
> > Signed-off-by: Andy Lutomirski <luto@kernel.org>
> > ---
> >  arch/x86/entry/entry_64_compat.S | 13 +++++++++++++
> >  1 file changed, 13 insertions(+)
>
> What do we say for the case when someone bisects, lands at this patch
> and, as Murphy would generally do it, has a reproducer which is calling
> SYSENTER/SYSCALL32?
>
> Tough luck?

Probably.  I really hope that no one does that.  Given how problematic
those instructions are outside the vdso, it would have to be a rather
strange reproducer.

>
> --
> Regards/Gruss,
>     Boris.
>
> ECO tip #101: Trim your mails when you reply.
> --
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#1243330 — [tip:x86/asm] x86/entry/64/compat: Disable SYSENTER and SYSCALL32 entries

Fromtip-bot for Andy Lutomirski <tipbot@zytor.com>
Date2015-10-09 15:10 +0200
Subject[tip:x86/asm] x86/entry/64/compat: Disable SYSENTER and SYSCALL32 entries
Message-ID<qhFAS-30e-11@gated-at.bofh.it>
In reply to#1240077
Commit-ID:  e62a254a1f93fcc7299497a5c7231639400b8c3c
Gitweb:     http://git.kernel.org/tip/e62a254a1f93fcc7299497a5c7231639400b8c3c
Author:     Andy Lutomirski <luto@kernel.org>
AuthorDate: Mon, 5 Oct 2015 17:48:02 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 9 Oct 2015 09:41:07 +0200

x86/entry/64/compat: Disable SYSENTER and SYSCALL32 entries

We've disabled the vDSO helpers to call them, so turn off the
entries entirely (temporarily) in preparation for cleaning them
up.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/8d6e84bf651519289dc532dcc230adfabbd2a3eb.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/entry/entry_64_compat.S | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index bc678f0..06a8966 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -103,6 +103,14 @@ ENTRY(entry_SYSENTER_compat)
 	jnz	sysenter_fix_flags
 sysenter_flags_fixed:
 
+	/* Temporary: SYSENTER is disabled. */
+#ifdef CONFIG_CONTEXT_TRACKING
+	call enter_from_user_mode
+#endif
+	ENABLE_INTERRUPTS(CLBR_NONE)
+	movl $11, %edi
+	call do_exit
+
 	/*
 	 * Re-enable interrupts.  IRQ tracing already thinks that IRQs are
 	 * on (since we treat user mode as having IRQs on), and the
@@ -324,6 +332,11 @@ ENTRY(entry_SYSCALL_compat)
 	 * it is too small to ever cause noticeable irq latency.
 	 */
 	SWAPGS_UNSAFE_STACK
+
+	/* Temporary: SYSCALL32 is disabled. */
+	movl	$-ENOSYS, %eax
+	USERGS_SYSRET32
+
 	movl	%esp, %r8d
 	movq	PER_CPU_VAR(cpu_current_top_of_stack), %rsp
 	ENABLE_INTERRUPTS(CLBR_NONE)
--
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