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Commit 7890ba8c authored by Ingo Molnar's avatar Ingo Molnar
Browse files

Merge branch 'stackprotector' into core/percpu

parents 99937d64 b2b062b8

arch/x86/Kconfig

+10 −13
Original line number Diff line number Diff line
@@ -1340,13 +1340,17 @@ config SECCOMP 


	  If unsure, say Y. Only embedded should say N here.



config CC_STACKPROTECTOR_ALL

	bool



config CC_STACKPROTECTOR

	bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"

	depends on X86_64 && EXPERIMENTAL && BROKEN

	depends on X86_64

	select CC_STACKPROTECTOR_ALL

	help

          This option turns on the -fstack-protector GCC feature. This

	  feature puts, at the beginning of critical functions, a canary

	  value on the stack just before the return address, and validates

	  feature puts, at the beginning of functions, a canary value on

	  the stack just before the return address, and validates

	  the value just before actually returning.  Stack based buffer

	  overflows (that need to overwrite this return address) now also

	  overwrite the canary, which gets detected and the attack is then
@@ -1354,15 +1358,8 @@ config CC_STACKPROTECTOR 


	  This feature requires gcc version 4.2 or above, or a distribution

	  gcc with the feature backported. Older versions are automatically

	  detected and for those versions, this configuration option is ignored.



config CC_STACKPROTECTOR_ALL

	bool "Use stack-protector for all functions"

	depends on CC_STACKPROTECTOR

	help

	  Normally, GCC only inserts the canary value protection for

	  functions that use large-ish on-stack buffers. By enabling

	  this option, GCC will be asked to do this for ALL functions.

	  detected and for those versions, this configuration option is

	  ignored. (and a warning is printed during bootup)



source kernel/Kconfig.hz

arch/x86/Kconfig.debug

+1 −0
Original line number Diff line number Diff line
@@ -117,6 +117,7 @@ config DEBUG_RODATA 
config DEBUG_RODATA_TEST

	bool "Testcase for the DEBUG_RODATA feature"

	depends on DEBUG_RODATA

	default y

	help

	  This option enables a testcase for the DEBUG_RODATA

	  feature as well as for the change_page_attr() infrastructure.

arch/x86/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -73,7 +73,7 @@ else 


        stackp := $(CONFIG_SHELL) $(srctree)/scripts/gcc-x86_64-has-stack-protector.sh

        stackp-$(CONFIG_CC_STACKPROTECTOR) := $(shell $(stackp) \

                "$(CC)" -fstack-protector )

                "$(CC)" "-fstack-protector -DGCC_HAS_SP" )

        stackp-$(CONFIG_CC_STACKPROTECTOR_ALL) += $(shell $(stackp) \

                "$(CC)" -fstack-protector-all )

arch/x86/include/asm/pda.h

+2 −2
Original line number Diff line number Diff line
@@ -17,11 +17,9 @@ struct x8664_pda { 
	unsigned long unused4;

	int unused5;

	unsigned int unused6;		/* 36 was cpunumber */

#ifdef CONFIG_CC_STACKPROTECTOR

	unsigned long stack_canary;	/* 40 stack canary value */

					/* gcc-ABI: this canary MUST be at

					   offset 40!!! */

#endif

	short in_bootmem;		/* pda lives in bootmem */

} ____cacheline_aligned_in_smp;
@@ -42,4 +40,6 @@ extern void pda_init(int); 


#endif



#define refresh_stack_canary() write_pda(stack_canary, current->stack_canary)



#endif /* _ASM_X86_PDA_H */

arch/x86/include/asm/stackprotector.h

0 → 100644
+39 −0
Original line number Diff line number Diff line 
#ifndef _ASM_STACKPROTECTOR_H

#define _ASM_STACKPROTECTOR_H 1



#include <asm/tsc.h>

#include <asm/pda.h>



/*

 * Initialize the stackprotector canary value.

 *

 * NOTE: this must only be called from functions that never return,

 * and it must always be inlined.

 */

static __always_inline void boot_init_stack_canary(void)

{

	u64 canary;

	u64 tsc;



	/*

	 * If we're the non-boot CPU, nothing set the PDA stack

	 * canary up for us - and if we are the boot CPU we have

	 * a 0 stack canary. This is a good place for updating

	 * it, as we wont ever return from this function (so the

	 * invalid canaries already on the stack wont ever

	 * trigger).

	 *

	 * We both use the random pool and the current TSC as a source

	 * of randomness. The TSC only matters for very early init,

	 * there it already has some randomness on most systems. Later

	 * on during the bootup the random pool has true entropy too.

	 */

	get_random_bytes(&canary, sizeof(canary));

	tsc = __native_read_tsc();

	canary += tsc + (tsc << 32UL);



	current->stack_canary = canary;

	write_pda(stack_canary, canary);

}



#endif