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From: Thomas Garnier <thgarnie@chromium.org>
To: kernel-hardening@lists.openwall.com
Cc: kristen@linux.intel.com, Thomas Garnier <thgarnie@chromium.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Juergen Gross <jgross@suse.com>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Thomas Garnier <thgarnie@google.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH v6 09/27] x86/boot/64: Adapt assembly for PIE support
Date: Thu, 31 Jan 2019 11:24:16 -0800	[thread overview]
Message-ID: <20190131192533.34130-10-thgarnie@chromium.org> (raw)
In-Reply-To: <20190131192533.34130-1-thgarnie@chromium.org>

Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.

Early at boot, the kernel is mapped at a temporary address while preparing
the page table. To know the changes needed for the page table with KASLR,
the boot code calculate the difference between the expected address of the
kernel and the one chosen by KASLR. It does not work with PIE because all
symbols in code are relatives. Instead of getting the future relocated
virtual address, you will get the current temporary mapping.
Instructions were changed to have absolute 64-bit references.

Position Independent Executable (PIE) support will allow to extend the
KASLR randomization range below 0xffffffff80000000.

Signed-off-by: Thomas Garnier <thgarnie@chromium.org>
---
 arch/x86/kernel/head_64.S | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index d1dbe8e4eb82..b9b6c6aa0313 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -90,8 +90,10 @@ startup_64:
 	popq	%rsi
 
 	/* Form the CR3 value being sure to include the CR3 modifier */
-	addq	$(early_top_pgt - __START_KERNEL_map), %rax
+	movabs  $(early_top_pgt - __START_KERNEL_map), %rcx
+	addq    %rcx, %rax
 	jmp 1f
+
 ENTRY(secondary_startup_64)
 	UNWIND_HINT_EMPTY
 	/*
@@ -120,7 +122,8 @@ ENTRY(secondary_startup_64)
 	popq	%rsi
 
 	/* Form the CR3 value being sure to include the CR3 modifier */
-	addq	$(init_top_pgt - __START_KERNEL_map), %rax
+	movabs	$(init_top_pgt - __START_KERNEL_map), %rcx
+	addq    %rcx, %rax
 1:
 
 	/* Enable PAE mode, PGE and LA57 */
@@ -138,7 +141,7 @@ ENTRY(secondary_startup_64)
 	movq	%rax, %cr3
 
 	/* Ensure I am executing from virtual addresses */
-	movq	$1f, %rax
+	movabs  $1f, %rax
 	ANNOTATE_RETPOLINE_SAFE
 	jmp	*%rax
 1:
@@ -235,11 +238,12 @@ ENTRY(secondary_startup_64)
 	 *	REX.W + FF /5 JMP m16:64 Jump far, absolute indirect,
 	 *		address given in m16:64.
 	 */
-	pushq	$.Lafter_lret	# put return address on stack for unwinder
+	movabs  $.Lafter_lret, %rax
+	pushq	%rax		# put return address on stack for unwinder
 	xorl	%ebp, %ebp	# clear frame pointer
-	movq	initial_code(%rip), %rax
+	leaq	initial_code(%rip), %rax
 	pushq	$__KERNEL_CS	# set correct cs
-	pushq	%rax		# target address in negative space
+	pushq	(%rax)		# target address in negative space
 	lretq
 .Lafter_lret:
 END(secondary_startup_64)
-- 
2.20.1.495.gaa96b0ce6b-goog


  parent reply	other threads:[~2019-01-31 19:28 UTC|newest]

Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-31 19:24 [PATCH v6 00/27] x86: PIE support and option to extend KASLR randomization Thomas Garnier
2019-01-31 19:24 ` Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 01/27] x86/crypto: Adapt assembly for PIE support Thomas Garnier
2019-02-07 11:48   ` Borislav Petkov
2019-02-07 17:01     ` Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 02/27] x86: Use symbol name in jump table " Thomas Garnier
2019-02-07 12:17   ` Borislav Petkov
2019-02-07 17:04     ` Thomas Garnier
2019-02-07 17:11       ` Borislav Petkov
2019-02-07 23:55         ` Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 03/27] x86: Add macro to get symbol address " Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 04/27] x86: relocate_kernel - Adapt assembly " Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 05/27] x86/entry/64: " Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 06/27] x86: pm-trace - " Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 07/27] x86/CPU: " Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 08/27] x86/acpi: " Thomas Garnier
2019-01-31 19:24 ` Thomas Garnier [this message]
2019-01-31 19:24 ` [PATCH v6 10/27] x86/power/64: " Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 11/27] x86/paravirt: " Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 12/27] x86/alternatives: " Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 13/27] x86/boot/64: Build head64.c as mcmodel large when PIE is enabled Thomas Garnier
2019-02-01 11:15   ` Kirill A. Shutemov
2019-02-01 17:11     ` Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 14/27] x86/percpu: Adapt percpu for PIE support Thomas Garnier
2019-01-31 20:57   ` Christopher Lameter
2019-01-31 22:49     ` Thomas Garnier
2019-01-31 22:49     ` Thomas Garnier
2019-02-01  2:31       ` Christopher Lameter
2019-02-01 17:13         ` Thomas Garnier
2019-04-08 15:58           ` Thomas Garnier
2019-04-08 15:58             ` [Xen-devel] " Thomas Garnier
2019-04-08 17:56             ` Christopher Lameter
2019-04-08 17:56               ` [Xen-devel] " Christopher Lameter
2019-04-08 18:08               ` Thomas Garnier
2019-04-08 18:08                 ` [Xen-devel] " Thomas Garnier
2019-04-08 18:08                 ` Thomas Garnier
2019-04-08 17:56             ` Christopher Lameter
2019-04-08 15:58           ` Thomas Garnier
2019-02-01 17:13         ` Thomas Garnier
2019-02-01  2:31       ` Christopher Lameter
2019-01-31 20:57   ` Christopher Lameter
2019-01-31 19:24 ` Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 15/27] compiler: Option to default to hidden symbols Thomas Garnier
2019-01-31 19:24   ` Thomas Garnier
2019-02-01  7:12   ` Dan Carpenter
2019-02-01  7:12     ` Dan Carpenter
2019-02-01 17:00     ` Thomas Garnier
2019-02-01 17:00       ` Thomas Garnier
2019-02-01  8:22   ` Adrian Hunter
2019-02-01  8:22     ` Adrian Hunter
2019-02-01 17:35     ` Thomas Garnier
2019-02-01 17:35       ` Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 16/27] compiler: Option to add PROVIDE_HIDDEN replacement for weak symbols Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 17/27] x86/relocs: Handle PIE relocations Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 18/27] xen: Adapt assembly for PIE support Thomas Garnier
2019-01-31 19:24 ` Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 19/27] kvm: " Thomas Garnier
2019-02-06 19:56   ` Sean Christopherson
2019-02-06 21:23     ` Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 20/27] x86: Support global stack cookie Thomas Garnier
2019-02-01 19:27   ` Andy Lutomirski
2019-02-01 20:21     ` Thomas Garnier
2019-02-01 22:36       ` Andy Lutomirski
2019-02-01 23:56         ` Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 21/27] x86/ftrace: Adapt function tracing for PIE support Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 22/27] x86/modules: Add option to start module section after kernel Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 23/27] x86/modules: Adapt module loading for PIE support Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 24/27] x86/mm: Make the x86 GOT read-only Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 25/27] x86/pie: Add option to build the kernel as PIE Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 26/27] x86/relocs: Add option to generate 64-bit relocations Thomas Garnier
2019-01-31 19:24 ` [PATCH v6 27/27] x86/kaslr: Add option to extend KASLR range from 1GB to 3GB Thomas Garnier
2019-01-31 19:59 ` [PATCH v6 00/27] x86: PIE support and option to extend KASLR randomization Kees Cook
2019-01-31 19:59 ` Kees Cook
2019-01-31 19:59   ` Kees Cook
2019-01-31 19:59 ` Kees Cook
2019-01-31 21:40 ` Konrad Rzeszutek Wilk
2019-01-31 21:40 ` Konrad Rzeszutek Wilk
2019-01-31 21:40   ` Konrad Rzeszutek Wilk
2019-01-31 22:42   ` Thomas Garnier
2019-01-31 22:42   ` Thomas Garnier
2019-01-31 22:42     ` Thomas Garnier
2019-01-31 21:40 ` Konrad Rzeszutek Wilk

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