From e19792ea63b4b8088fe00575bd0d8c591decb817 Mon Sep 17 00:00:00 2001
From: mortimer <mortimer@cvs.openbsd.org>
Date: Sat, 30 Mar 2019 12:38:00 +0000
Subject: Add retguard macros to setjmp/longjmp on amd64. Knocks out some
 useful gadgets from libc.

ok deraadt@, kettenis@
---
 lib/libc/arch/amd64/gen/_setjmp.S   | 18 +++++++++++-------
 lib/libc/arch/amd64/gen/setjmp.S    | 18 +++++++++++-------
 lib/libc/arch/amd64/gen/sigsetjmp.S | 18 +++++++++++-------
 3 files changed, 33 insertions(+), 21 deletions(-)

(limited to 'lib/libc/arch')

diff --git a/lib/libc/arch/amd64/gen/_setjmp.S b/lib/libc/arch/amd64/gen/_setjmp.S
index 904828d2953..1aef964c102 100644
--- a/lib/libc/arch/amd64/gen/_setjmp.S
+++ b/lib/libc/arch/amd64/gen/_setjmp.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: _setjmp.S,v 1.3 2016/05/12 15:46:03 deraadt Exp $	*/
+/*	$OpenBSD: _setjmp.S,v 1.4 2019/03/30 12:37:59 mortimer Exp $	*/
 /*	$NetBSD: _setjmp.S,v 1.1 2001/06/19 00:25:02 fvdl Exp $	*/
 
 /*
@@ -53,6 +53,7 @@
  */
 
 ENTRY(_setjmp)
+	RETGUARD_SETUP(_setjmp, r10)
 	movq    (%rsp),%r11
 	leaq	__jmpxor(%rip),%rcx
 	movq    %rbx,(_JB_RBX * 8)(%rdi)
@@ -72,11 +73,19 @@ ENTRY(_setjmp)
 	xorq	%rcx,%rcx
 
 	xorq	%rax,%rax
+	RETGUARD_CHECK(_setjmp, r10)
 	ret
 END(_setjmp)
 
 ENTRY(_longjmp)
 	leaq	 __jmpxor(%rip),%rcx
+	movq    (_JB_RSP * 8)(%rdi),%r11
+	xorq	(1*8)(%rcx),%r11
+	movq	%r11,%rsp
+	movq    (_JB_PC  * 8)(%rdi),%r11
+	xorq	(2*8)(%rcx),%r11
+	movq	%r11,0(%rsp)
+	RETGUARD_SETUP(_longjmp, r10)
 	movq    (_JB_RBX * 8)(%rdi),%rbx
 	movq    (_JB_RBP * 8)(%rdi),%r11
 	xorq    (0*8)(%rcx),%r11
@@ -85,17 +94,12 @@ ENTRY(_longjmp)
 	movq    (_JB_R13 * 8)(%rdi),%r13
 	movq    (_JB_R14 * 8)(%rdi),%r14
 	movq    (_JB_R15 * 8)(%rdi),%r15
-	movq    (_JB_RSP * 8)(%rdi),%r11
-	xorq	(1*8)(%rcx),%r11
-	movq	%r11,%rsp
-	movq    (_JB_PC  * 8)(%rdi),%r11
-	xorq	(2*8)(%rcx),%r11
 	xorq	%rcx,%rcx
 
 	movl	%esi,%eax
 	testl	%eax,%eax
 	jnz	1f
 	incl	%eax
-1:	movq	%r11,0(%rsp)
+1:	RETGUARD_CHECK(_longjmp, r10)
 	ret
 END(_longjmp)
diff --git a/lib/libc/arch/amd64/gen/setjmp.S b/lib/libc/arch/amd64/gen/setjmp.S
index 751471216ee..ecb6a353ebf 100644
--- a/lib/libc/arch/amd64/gen/setjmp.S
+++ b/lib/libc/arch/amd64/gen/setjmp.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: setjmp.S,v 1.7 2016/05/29 22:39:21 guenther Exp $	*/
+/*	$OpenBSD: setjmp.S,v 1.8 2019/03/30 12:37:59 mortimer Exp $	*/
 /*	$NetBSD: __setjmp14.S,v 1.1 2001/06/19 00:25:02 fvdl Exp $	*/
 
 /*
@@ -59,6 +59,7 @@ __jmpxor:
  */
 
 ENTRY(setjmp)
+	RETGUARD_SETUP(setjmp, r10)
 	movq	%rdi,%r8		/* save jmpbuf addr */
 	movl	$1,%edi			/* how = SIG_BLOCK */
 	xorl	%esi,%esi		/* set = empty */
@@ -86,6 +87,7 @@ ENTRY(setjmp)
 	xorq	%rcx,%rcx
 
 	xorq	%rax,%rax
+	RETGUARD_CHECK(setjmp, r10)
 	ret
 END(setjmp)
 
@@ -100,6 +102,13 @@ ENTRY(longjmp)
 	movl	%r8d,%eax
 
 	leaq	 __jmpxor(%rip),%rcx
+	movq	(_JB_RSP * 8)(%r12),%r11
+	xorq	(1*8)(%rcx),%r11
+	movq	%r11,%rsp
+	movq	(_JB_PC  * 8)(%r12),%r11
+	xorq	(2*8)(%rcx),%r11
+	movq	%r11,0(%rsp)
+	RETGUARD_SETUP(longjmp, r10)
 	movq	(_JB_RBX * 8)(%r12),%rbx
 	movq	(_JB_RBP * 8)(%r12),%r11
 	xorq	(0*8)(%rcx),%r11
@@ -107,17 +116,12 @@ ENTRY(longjmp)
 	movq	(_JB_R13 * 8)(%r12),%r13
 	movq	(_JB_R14 * 8)(%r12),%r14
 	movq	(_JB_R15 * 8)(%r12),%r15
-	movq	(_JB_RSP * 8)(%r12),%r11
-	xorq	(1*8)(%rcx),%r11
-	movq	%r11,%rsp
-	movq	(_JB_PC  * 8)(%r12),%r11
-	xorq	(2*8)(%rcx),%r11
 	movq	(_JB_R12 * 8)(%r12),%r12
 	xorq	%rcx,%rcx
 
 	testl	%eax,%eax
 	jnz	1f
 	incl	%eax
-1:	movq	%r11,0(%rsp)
+1:	RETGUARD_CHECK(longjmp, r10)
 	ret
 END(longjmp)
diff --git a/lib/libc/arch/amd64/gen/sigsetjmp.S b/lib/libc/arch/amd64/gen/sigsetjmp.S
index ecce6204b26..22414c1fc87 100644
--- a/lib/libc/arch/amd64/gen/sigsetjmp.S
+++ b/lib/libc/arch/amd64/gen/sigsetjmp.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sigsetjmp.S,v 1.7 2016/05/29 22:39:21 guenther Exp $	*/
+/*	$OpenBSD: sigsetjmp.S,v 1.8 2019/03/30 12:37:59 mortimer Exp $	*/
 /*	$NetBSD: __setjmp14.S,v 1.1 2001/06/19 00:25:02 fvdl Exp $	*/
 
 /*
@@ -53,6 +53,7 @@
  */
 
 ENTRY(sigsetjmp)
+	RETGUARD_SETUP(sigsetjmp, r10)
 	movl    %esi,(_JB_SIGFLAG  * 8)(%rdi)
 	testl   %esi,%esi
 	jz      2f
@@ -84,6 +85,7 @@ ENTRY(sigsetjmp)
 	xorq	%rcx,%rcx
 
 	xorq	%rax,%rax
+	RETGUARD_CHECK(sigsetjmp, r10)
 	ret
 END(sigsetjmp)
 
@@ -100,6 +102,13 @@ ENTRY(siglongjmp)
 2:	movl	%r8d,%eax
 
 	leaq	 __jmpxor(%rip),%rcx
+	movq	(_JB_RSP * 8)(%r12),%r11
+	xorq	(1*8)(%rcx),%r11
+	movq	%r11,%rsp
+	movq	(_JB_PC  * 8)(%r12),%r11
+	xorq	(2*8)(%rcx),%r11
+	movq	%r11,0(%rsp)
+	RETGUARD_SETUP(siglongjmp, r10)
 	movq	(_JB_RBX * 8)(%r12),%rbx
 	movq	(_JB_RBP * 8)(%r12),%r11
 	xorq	(0*8)(%rcx),%r11
@@ -107,17 +116,12 @@ ENTRY(siglongjmp)
 	movq	(_JB_R13 * 8)(%r12),%r13
 	movq	(_JB_R14 * 8)(%r12),%r14
 	movq	(_JB_R15 * 8)(%r12),%r15
-	movq	(_JB_RSP * 8)(%r12),%r11
-	xorq	(1*8)(%rcx),%r11
-	movq	%r11,%rsp
-	movq	(_JB_PC  * 8)(%r12),%r11
-	xorq	(2*8)(%rcx),%r11
 	movq	(_JB_R12 * 8)(%r12),%r12
 	xorq	%rcx,%rcx
 
 	testl	%eax,%eax
 	jnz	1f
 	incl	%eax
-1:	movq	%r11,0(%rsp)
+1:	RETGUARD_CHECK(siglongjmp, r10)
 	ret
 END(siglongjmp)
-- 
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