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

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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
This commit is contained in:
Linus Torvalds 2014-03-31 12:34:49 -07:00
commit e06df6a7ea
2 changed files with 45 additions and 5 deletions
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4
Documentation/kernel-parameters.txt
View file

@ -2060,8 +2060,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
IOAPICs that may be present in the system. IOAPICs that may be present in the system.
nokaslr [X86] nokaslr [X86]
Disable kernel base offset ASLR (Address Space Disable kernel and module base offset ASLR (Address
Layout Randomization) if built into the kernel. Space Layout Randomization) if built into the kernel.
noautogroup Disable scheduler automatic task group creation. noautogroup Disable scheduler automatic task group creation.

46
arch/x86/kernel/module.c
View file

@ -28,6 +28,7 @@
#include <linux/mm.h> #include <linux/mm.h>
#include <linux/gfp.h> #include <linux/gfp.h>
#include <linux/jump_label.h> #include <linux/jump_label.h>
#include <linux/random.h>
#include <asm/page.h> #include <asm/page.h>
#include <asm/pgtable.h> #include <asm/pgtable.h>
@ -43,13 +44,52 @@ do { \
} while (0) } while (0)
#endif #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) void *module_alloc(unsigned long size)
{ {
if (PAGE_ALIGN(size) > MODULES_LEN) if (PAGE_ALIGN(size) > MODULES_LEN)
return NULL; return NULL;
return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END, return __vmalloc_node_range(size, 1,
GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC, MODULES_VADDR + get_module_load_offset(),
NUMA_NO_NODE, __builtin_return_address(0)); MODULES_END, GFP_KERNEL | __GFP_HIGHMEM,
PAGE_KERNEL_EXEC, NUMA_NO_NODE,
__builtin_return_address(0));
} }
#ifdef CONFIG_X86_32 #ifdef CONFIG_X86_32