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s390/kaslr: randomize module base load address

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Randomize the load address of modules in the kernel to make KASLR effective
for modules.
This is the s390 variant of commit e2b32e6785 ("x86, kaslr: randomize
module base load address").

Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2023-03-31 15:03:23 +02:00 committed by Vasily Gorbik
parent bb87190c9d
commit 34644cc2e1
1 changed files with 21 additions and 1 deletions
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22
arch/s390/kernel/module.c
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@ -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)) {