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Commit e06df6a7 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'x86-kaslr-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 kaslr update from Ingo Molnar:
 "This adds kernel module load address randomization"

* 'x86-kaslr-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, kaslr: fix module lock ordering problem
  x86, kaslr: randomize module base load address
parents c0fc3cba 9dd721c6

Documentation/kernel-parameters.txt

+2 −2
Original line number Diff line number Diff line
@@ -2060,8 +2060,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 
			IOAPICs that may be present in the system.



	nokaslr		[X86]

			Disable kernel base offset ASLR (Address Space

			Layout Randomization) if built into the kernel.

			Disable kernel and module base offset ASLR (Address

			Space Layout Randomization) if built into the kernel.



	noautogroup	Disable scheduler automatic task group creation.

arch/x86/kernel/module.c

+43 −3
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include <linux/mm.h>

#include <linux/gfp.h>

#include <linux/jump_label.h>

#include <linux/random.h>



#include <asm/page.h>

#include <asm/pgtable.h>
@@ -43,13 +44,52 @@ do { \ 
} while (0)

#endif



#ifdef CONFIG_RANDOMIZE_BASE

static unsigned long module_load_offset;

static int randomize_modules = 1;



/* Mutex protects the module_load_offset. */

static DEFINE_MUTEX(module_kaslr_mutex);



static int __init parse_nokaslr(char *p)

{

	randomize_modules = 0;

	return 0;

}

early_param("nokaslr", parse_nokaslr);



static unsigned long int get_module_load_offset(void)

{

	if (randomize_modules) {

		mutex_lock(&module_kaslr_mutex);

		/*

		 * Calculate the module_load_offset the first time this

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

		 * reboot.

		 */

		if (module_load_offset == 0)

			module_load_offset =

				(get_random_int() % 1024 + 1) * PAGE_SIZE;

		mutex_unlock(&module_kaslr_mutex);

	}

	return module_load_offset;

}

#else

static unsigned long int get_module_load_offset(void)

{

	return 0;

}

#endif



void *module_alloc(unsigned long size)

{

	if (PAGE_ALIGN(size) > MODULES_LEN)

		return NULL;

	return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,

				GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC,

				NUMA_NO_NODE, __builtin_return_address(0));

	return __vmalloc_node_range(size, 1,

				    MODULES_VADDR + get_module_load_offset(),

				    MODULES_END, GFP_KERNEL | __GFP_HIGHMEM,

				    PAGE_KERNEL_EXEC, NUMA_NO_NODE,

				    __builtin_return_address(0));

}



#ifdef CONFIG_X86_32