Commit 34644cc2 authored by Heiko Carstens's avatar Heiko Carstens Committed by Vasily Gorbik
Browse files

s390/kaslr: randomize module base load address 



Randomize the load address of modules in the kernel to make KASLR effective
for modules.
This is the s390 variant of commit e2b32e67 ("x86, kaslr: randomize
module base load address").

Reviewed-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent bb87190c

arch/s390/kernel/module.c

+21 −1
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#include <asm/facility.h>

#include <asm/ftrace.lds.h>

#include <asm/set_memory.h>

#include <asm/setup.h>



#if 0

#define DEBUGP printk
@@ -35,6 +36,24 @@ 


#define PLT_ENTRY_SIZE 22



static unsigned long get_module_load_offset(void)

{

	static DEFINE_MUTEX(module_kaslr_mutex);

	static unsigned long module_load_offset;



	if (!kaslr_enabled())

		return 0;

	/*

	 * Calculate the module_load_offset the first time this code

	 * is called. Once calculated it stays the same until reboot.

	 */

	mutex_lock(&module_kaslr_mutex);

	if (!module_load_offset)

		module_load_offset = get_random_u32_inclusive(1, 1024) * PAGE_SIZE;

	mutex_unlock(&module_kaslr_mutex);

	return module_load_offset;

}



void *module_alloc(unsigned long size)

{

	gfp_t gfp_mask = GFP_KERNEL;
@@ -42,7 +61,8 @@ void *module_alloc(unsigned long size) 


	if (PAGE_ALIGN(size) > MODULES_LEN)

		return NULL;

	p = __vmalloc_node_range(size, MODULE_ALIGN, MODULES_VADDR, MODULES_END,

	p = __vmalloc_node_range(size, MODULE_ALIGN,

				 MODULES_VADDR + get_module_load_offset(), MODULES_END,

				 gfp_mask, PAGE_KERNEL_EXEC, VM_DEFER_KMEMLEAK, NUMA_NO_NODE,

				 __builtin_return_address(0));

	if (p && (kasan_alloc_module_shadow(p, size, gfp_mask) < 0)) {