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x86: Support shadow stack pointer in setjmp/longjmp

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Save and restore shadow stack pointer in setjmp and longjmp to support
shadow stack in Intel CET.  Use feature_1 in tcbhead_t to check if
shadow stack is enabled before saving and restoring shadow stack pointer.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

	* sysdeps/i386/__longjmp.S: Include <jmp_buf-ssp.h>.
	(__longjmp): Restore shadow stack pointer if shadow stack is
	enabled, SHADOW_STACK_POINTER_OFFSET is defined and __longjmp
	isn't defined for __longjmp_cancel.
	* sysdeps/i386/bsd-_setjmp.S: Include <jmp_buf-ssp.h>.
	(_setjmp): Save shadow stack pointer if shadow stack is enabled
	and SHADOW_STACK_POINTER_OFFSET is defined.
	* sysdeps/i386/bsd-setjmp.S: Include <jmp_buf-ssp.h>.
	(setjmp): Save shadow stack pointer if shadow stack is enabled
	and SHADOW_STACK_POINTER_OFFSET is defined.
	* sysdeps/i386/setjmp.S: Include <jmp_buf-ssp.h>.
	(__sigsetjmp): Save shadow stack pointer if shadow stack is
	enabled and SHADOW_STACK_POINTER_OFFSET is defined.
	* sysdeps/unix/sysv/linux/i386/____longjmp_chk.S: Include
	<jmp_buf-ssp.h>.
	(____longjmp_chk): Restore shadow stack pointer if shadow stack
	is enabled and SHADOW_STACK_POINTER_OFFSET is defined.
	* sysdeps/unix/sysv/linux/x86/Makefile (gen-as-const-headers):
	Remove jmp_buf-ssp.sym.
	* sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S: Include
	<jmp_buf-ssp.h>.
	(____longjmp_chk): Restore shadow stack pointer if shadow stack
	is enabled and SHADOW_STACK_POINTER_OFFSET is defined.
	* sysdeps/x86/Makefile (gen-as-const-headers): Add
	jmp_buf-ssp.sym.
	* sysdeps/x86/jmp_buf-ssp.sym: New dummy file.
	* sysdeps/x86_64/__longjmp.S: Include <jmp_buf-ssp.h>.
	(__longjmp): Restore shadow stack pointer if shadow stack is
	enabled, SHADOW_STACK_POINTER_OFFSET is defined and __longjmp
	isn't defined for __longjmp_cancel.
	* sysdeps/x86_64/setjmp.S: Include <jmp_buf-ssp.h>.
	(__sigsetjmp): Save shadow stack pointer if shadow stack is
	enabled and SHADOW_STACK_POINTER_OFFSET is defined.
This commit is contained in:
H.J. Lu
2018-07-14 05:59:29 -07:00
parent ebff9c5cfa
commit faaee1f07e
12 changed files with 315 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

37
sysdeps/unix/sysv/linux/i386/____longjmp_chk.S
View File

@ -17,9 +17,14 @@
#include <sysdep.h>
#include <jmpbuf-offsets.h>
#include <jmp_buf-ssp.h>
#include <asm-syntax.h>
#include <stap-probe.h>
/* Don't restore shadow stack register if shadow stack isn't enabled. */
#if !SHSTK_ENABLED
# undef SHADOW_STACK_POINTER_OFFSET
#endif
.section .rodata.str1.1,"aMS",@progbits,1
.type longjmp_msg,@object
@ -46,6 +51,38 @@ longjmp_msg:
ENTRY (____longjmp_chk)
movl 4(%esp), %ecx /* User's jmp_buf in %ecx. */
#ifdef SHADOW_STACK_POINTER_OFFSET
# if IS_IN (libc) && defined SHARED && defined FEATURE_1_OFFSET
/* Check if Shadow Stack is enabled. */
testl $X86_FEATURE_1_SHSTK, %gs:FEATURE_1_OFFSET
jz L(skip_ssp)
# else
xorl %edx, %edx
# endif
/* Check and adjust the Shadow-Stack-Pointer. */
rdsspd %edx
/* And compare it with the saved ssp value. */
subl SHADOW_STACK_POINTER_OFFSET(%ecx), %edx
je L(skip_ssp)
/* Count the number of frames to adjust and adjust it
with incssp instruction. The instruction can adjust
the ssp by [0..255] value only thus use a loop if
the number of frames is bigger than 255. */
negl %edx
shrl $2, %edx
/* NB: We saved Shadow-Stack-Pointer of setjmp. Since we are
restoring Shadow-Stack-Pointer of setjmp's caller, we
need to unwind shadow stack by one more frame. */
addl $1, %edx
movl $255, %ebx
L(loop):
cmpl %ebx, %edx
cmovb %edx, %ebx
incsspd %ebx
subl %ebx, %edx
ja L(loop)
L(skip_ssp):
#endif
/* Save the return address now. */
movl (JB_PC*4)(%ecx), %edx
/* Get the stack pointer. */

1
sysdeps/unix/sysv/linux/x86/Makefile
View File

@ -21,6 +21,5 @@ sysdep_routines += dl-vdso
endif
ifeq ($(subdir),setjmp)
gen-as-const-headers += jmp_buf-ssp.sym
tests += tst-saved_mask-1
endif

38
sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S
View File

@ -20,7 +20,13 @@
#include <asm-syntax.h>
#include <stap-probe.h>
/* Don't restore shadow stack register if shadow stack isn't enabled. */
#if !SHSTK_ENABLED
# undef SHADOW_STACK_POINTER_OFFSET
#endif
#include <sigaltstack-offsets.h>
#include <jmp_buf-ssp.h>
.section .rodata.str1.1,"aMS",@progbits,1
.type longjmp_msg,@object
@ -105,6 +111,38 @@ ENTRY(____longjmp_chk)
cfi_restore (%rsi)
.Lok:
#ifdef SHADOW_STACK_POINTER_OFFSET
# if IS_IN (libc) && defined SHARED && defined FEATURE_1_OFFSET
/* Check if Shadow Stack is enabled. */
testl $X86_FEATURE_1_SHSTK, %fs:FEATURE_1_OFFSET
jz L(skip_ssp)
# else
xorl %eax, %eax
# endif
/* Check and adjust the Shadow-Stack-Pointer. */
rdsspq %rax
/* And compare it with the saved ssp value. */
subq SHADOW_STACK_POINTER_OFFSET(%rdi), %rax
je L(skip_ssp)
/* Count the number of frames to adjust and adjust it
with incssp instruction. The instruction can adjust
the ssp by [0..255] value only thus use a loop if
the number of frames is bigger than 255. */
negq %rax
shrq $3, %rax
/* NB: We saved Shadow-Stack-Pointer of setjmp. Since we are
restoring Shadow-Stack-Pointer of setjmp's caller, we
need to unwind shadow stack by one more frame. */
addq $1, %rax
movl $255, %ebx
L(loop):
cmpq %rbx, %rax
cmovb %rax, %rbx
incsspq %rbx
subq %rbx, %rax
ja L(loop)
L(skip_ssp):
#endif
LIBC_PROBE (longjmp, 3, LP_SIZE@%RDI_LP, -4@%esi, LP_SIZE@%RDX_LP)
/* We add unwind information for the target here. */
cfi_def_cfa(%rdi, 0)