linux/mm/kasan/kasan.c
Andrey Ryabinin bebf56a1b1 kasan: enable instrumentation of global variables
This feature let us to detect accesses out of bounds of global variables.
This will work as for globals in kernel image, so for globals in modules.
Currently this won't work for symbols in user-specified sections (e.g.
__init, __read_mostly, ...)

The idea of this is simple.  Compiler increases each global variable by
redzone size and add constructors invoking __asan_register_globals()
function.  Information about global variable (address, size, size with
redzone ...) passed to __asan_register_globals() so we could poison
variable's redzone.

This patch also forces module_alloc() to return 8*PAGE_SIZE aligned
address making shadow memory handling (
kasan_module_alloc()/kasan_module_free() ) more simple.  Such alignment
guarantees that each shadow page backing modules address space correspond
to only one module_alloc() allocation.

Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: Andrey Konovalov <adech.fo@gmail.com>
Cc: Yuri Gribov <tetra2005@gmail.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-13 21:21:42 -08:00

517 lines
12 KiB
C

/*
* This file contains shadow memory manipulation code.
*
* Copyright (c) 2014 Samsung Electronics Co., Ltd.
* Author: Andrey Ryabinin <a.ryabinin@samsung.com>
*
* Some of code borrowed from https://github.com/xairy/linux by
* Andrey Konovalov <adech.fo@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#define DISABLE_BRANCH_PROFILING
#include <linux/export.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/memblock.h>
#include <linux/memory.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/printk.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/stacktrace.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/kasan.h>
#include "kasan.h"
#include "../slab.h"
/*
* Poisons the shadow memory for 'size' bytes starting from 'addr'.
* Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE.
*/
static void kasan_poison_shadow(const void *address, size_t size, u8 value)
{
void *shadow_start, *shadow_end;
shadow_start = kasan_mem_to_shadow(address);
shadow_end = kasan_mem_to_shadow(address + size);
memset(shadow_start, value, shadow_end - shadow_start);
}
void kasan_unpoison_shadow(const void *address, size_t size)
{
kasan_poison_shadow(address, size, 0);
if (size & KASAN_SHADOW_MASK) {
u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size);
*shadow = size & KASAN_SHADOW_MASK;
}
}
/*
* All functions below always inlined so compiler could
* perform better optimizations in each of __asan_loadX/__assn_storeX
* depending on memory access size X.
*/
static __always_inline bool memory_is_poisoned_1(unsigned long addr)
{
s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr);
if (unlikely(shadow_value)) {
s8 last_accessible_byte = addr & KASAN_SHADOW_MASK;
return unlikely(last_accessible_byte >= shadow_value);
}
return false;
}
static __always_inline bool memory_is_poisoned_2(unsigned long addr)
{
u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
if (unlikely(*shadow_addr)) {
if (memory_is_poisoned_1(addr + 1))
return true;
if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0))
return false;
return unlikely(*(u8 *)shadow_addr);
}
return false;
}
static __always_inline bool memory_is_poisoned_4(unsigned long addr)
{
u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
if (unlikely(*shadow_addr)) {
if (memory_is_poisoned_1(addr + 3))
return true;
if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3))
return false;
return unlikely(*(u8 *)shadow_addr);
}
return false;
}
static __always_inline bool memory_is_poisoned_8(unsigned long addr)
{
u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
if (unlikely(*shadow_addr)) {
if (memory_is_poisoned_1(addr + 7))
return true;
if (likely(((addr + 7) & KASAN_SHADOW_MASK) >= 7))
return false;
return unlikely(*(u8 *)shadow_addr);
}
return false;
}
static __always_inline bool memory_is_poisoned_16(unsigned long addr)
{
u32 *shadow_addr = (u32 *)kasan_mem_to_shadow((void *)addr);
if (unlikely(*shadow_addr)) {
u16 shadow_first_bytes = *(u16 *)shadow_addr;
s8 last_byte = (addr + 15) & KASAN_SHADOW_MASK;
if (unlikely(shadow_first_bytes))
return true;
if (likely(!last_byte))
return false;
return memory_is_poisoned_1(addr + 15);
}
return false;
}
static __always_inline unsigned long bytes_is_zero(const u8 *start,
size_t size)
{
while (size) {
if (unlikely(*start))
return (unsigned long)start;
start++;
size--;
}
return 0;
}
static __always_inline unsigned long memory_is_zero(const void *start,
const void *end)
{
unsigned int words;
unsigned long ret;
unsigned int prefix = (unsigned long)start % 8;
if (end - start <= 16)
return bytes_is_zero(start, end - start);
if (prefix) {
prefix = 8 - prefix;
ret = bytes_is_zero(start, prefix);
if (unlikely(ret))
return ret;
start += prefix;
}
words = (end - start) / 8;
while (words) {
if (unlikely(*(u64 *)start))
return bytes_is_zero(start, 8);
start += 8;
words--;
}
return bytes_is_zero(start, (end - start) % 8);
}
static __always_inline bool memory_is_poisoned_n(unsigned long addr,
size_t size)
{
unsigned long ret;
ret = memory_is_zero(kasan_mem_to_shadow((void *)addr),
kasan_mem_to_shadow((void *)addr + size - 1) + 1);
if (unlikely(ret)) {
unsigned long last_byte = addr + size - 1;
s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
if (unlikely(ret != (unsigned long)last_shadow ||
((last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
return true;
}
return false;
}
static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
{
if (__builtin_constant_p(size)) {
switch (size) {
case 1:
return memory_is_poisoned_1(addr);
case 2:
return memory_is_poisoned_2(addr);
case 4:
return memory_is_poisoned_4(addr);
case 8:
return memory_is_poisoned_8(addr);
case 16:
return memory_is_poisoned_16(addr);
default:
BUILD_BUG();
}
}
return memory_is_poisoned_n(addr, size);
}
static __always_inline void check_memory_region(unsigned long addr,
size_t size, bool write)
{
struct kasan_access_info info;
if (unlikely(size == 0))
return;
if (unlikely((void *)addr <
kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
info.access_addr = (void *)addr;
info.access_size = size;
info.is_write = write;
info.ip = _RET_IP_;
kasan_report_user_access(&info);
return;
}
if (likely(!memory_is_poisoned(addr, size)))
return;
kasan_report(addr, size, write, _RET_IP_);
}
void __asan_loadN(unsigned long addr, size_t size);
void __asan_storeN(unsigned long addr, size_t size);
#undef memset
void *memset(void *addr, int c, size_t len)
{
__asan_storeN((unsigned long)addr, len);
return __memset(addr, c, len);
}
#undef memmove
void *memmove(void *dest, const void *src, size_t len)
{
__asan_loadN((unsigned long)src, len);
__asan_storeN((unsigned long)dest, len);
return __memmove(dest, src, len);
}
#undef memcpy
void *memcpy(void *dest, const void *src, size_t len)
{
__asan_loadN((unsigned long)src, len);
__asan_storeN((unsigned long)dest, len);
return __memcpy(dest, src, len);
}
void kasan_alloc_pages(struct page *page, unsigned int order)
{
if (likely(!PageHighMem(page)))
kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order);
}
void kasan_free_pages(struct page *page, unsigned int order)
{
if (likely(!PageHighMem(page)))
kasan_poison_shadow(page_address(page),
PAGE_SIZE << order,
KASAN_FREE_PAGE);
}
void kasan_poison_slab(struct page *page)
{
kasan_poison_shadow(page_address(page),
PAGE_SIZE << compound_order(page),
KASAN_KMALLOC_REDZONE);
}
void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
{
kasan_unpoison_shadow(object, cache->object_size);
}
void kasan_poison_object_data(struct kmem_cache *cache, void *object)
{
kasan_poison_shadow(object,
round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE),
KASAN_KMALLOC_REDZONE);
}
void kasan_slab_alloc(struct kmem_cache *cache, void *object)
{
kasan_kmalloc(cache, object, cache->object_size);
}
void kasan_slab_free(struct kmem_cache *cache, void *object)
{
unsigned long size = cache->object_size;
unsigned long rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
/* RCU slabs could be legally used after free within the RCU period */
if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
return;
kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
}
void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size)
{
unsigned long redzone_start;
unsigned long redzone_end;
if (unlikely(object == NULL))
return;
redzone_start = round_up((unsigned long)(object + size),
KASAN_SHADOW_SCALE_SIZE);
redzone_end = round_up((unsigned long)object + cache->object_size,
KASAN_SHADOW_SCALE_SIZE);
kasan_unpoison_shadow(object, size);
kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
KASAN_KMALLOC_REDZONE);
}
EXPORT_SYMBOL(kasan_kmalloc);
void kasan_kmalloc_large(const void *ptr, size_t size)
{
struct page *page;
unsigned long redzone_start;
unsigned long redzone_end;
if (unlikely(ptr == NULL))
return;
page = virt_to_page(ptr);
redzone_start = round_up((unsigned long)(ptr + size),
KASAN_SHADOW_SCALE_SIZE);
redzone_end = (unsigned long)ptr + (PAGE_SIZE << compound_order(page));
kasan_unpoison_shadow(ptr, size);
kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
KASAN_PAGE_REDZONE);
}
void kasan_krealloc(const void *object, size_t size)
{
struct page *page;
if (unlikely(object == ZERO_SIZE_PTR))
return;
page = virt_to_head_page(object);
if (unlikely(!PageSlab(page)))
kasan_kmalloc_large(object, size);
else
kasan_kmalloc(page->slab_cache, object, size);
}
void kasan_kfree_large(const void *ptr)
{
struct page *page = virt_to_page(ptr);
kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
KASAN_FREE_PAGE);
}
int kasan_module_alloc(void *addr, size_t size)
{
void *ret;
size_t shadow_size;
unsigned long shadow_start;
shadow_start = (unsigned long)kasan_mem_to_shadow(addr);
shadow_size = round_up(size >> KASAN_SHADOW_SCALE_SHIFT,
PAGE_SIZE);
if (WARN_ON(!PAGE_ALIGNED(shadow_start)))
return -EINVAL;
ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
shadow_start + shadow_size,
GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
__builtin_return_address(0));
return ret ? 0 : -ENOMEM;
}
void kasan_module_free(void *addr)
{
vfree(kasan_mem_to_shadow(addr));
}
static void register_global(struct kasan_global *global)
{
size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
kasan_unpoison_shadow(global->beg, global->size);
kasan_poison_shadow(global->beg + aligned_size,
global->size_with_redzone - aligned_size,
KASAN_GLOBAL_REDZONE);
}
void __asan_register_globals(struct kasan_global *globals, size_t size)
{
int i;
for (i = 0; i < size; i++)
register_global(&globals[i]);
}
EXPORT_SYMBOL(__asan_register_globals);
void __asan_unregister_globals(struct kasan_global *globals, size_t size)
{
}
EXPORT_SYMBOL(__asan_unregister_globals);
#define DEFINE_ASAN_LOAD_STORE(size) \
void __asan_load##size(unsigned long addr) \
{ \
check_memory_region(addr, size, false); \
} \
EXPORT_SYMBOL(__asan_load##size); \
__alias(__asan_load##size) \
void __asan_load##size##_noabort(unsigned long); \
EXPORT_SYMBOL(__asan_load##size##_noabort); \
void __asan_store##size(unsigned long addr) \
{ \
check_memory_region(addr, size, true); \
} \
EXPORT_SYMBOL(__asan_store##size); \
__alias(__asan_store##size) \
void __asan_store##size##_noabort(unsigned long); \
EXPORT_SYMBOL(__asan_store##size##_noabort)
DEFINE_ASAN_LOAD_STORE(1);
DEFINE_ASAN_LOAD_STORE(2);
DEFINE_ASAN_LOAD_STORE(4);
DEFINE_ASAN_LOAD_STORE(8);
DEFINE_ASAN_LOAD_STORE(16);
void __asan_loadN(unsigned long addr, size_t size)
{
check_memory_region(addr, size, false);
}
EXPORT_SYMBOL(__asan_loadN);
__alias(__asan_loadN)
void __asan_loadN_noabort(unsigned long, size_t);
EXPORT_SYMBOL(__asan_loadN_noabort);
void __asan_storeN(unsigned long addr, size_t size)
{
check_memory_region(addr, size, true);
}
EXPORT_SYMBOL(__asan_storeN);
__alias(__asan_storeN)
void __asan_storeN_noabort(unsigned long, size_t);
EXPORT_SYMBOL(__asan_storeN_noabort);
/* to shut up compiler complaints */
void __asan_handle_no_return(void) {}
EXPORT_SYMBOL(__asan_handle_no_return);
#ifdef CONFIG_MEMORY_HOTPLUG
static int kasan_mem_notifier(struct notifier_block *nb,
unsigned long action, void *data)
{
return (action == MEM_GOING_ONLINE) ? NOTIFY_BAD : NOTIFY_OK;
}
static int __init kasan_memhotplug_init(void)
{
pr_err("WARNING: KASan doesn't support memory hot-add\n");
pr_err("Memory hot-add will be disabled\n");
hotplug_memory_notifier(kasan_mem_notifier, 0);
return 0;
}
module_init(kasan_memhotplug_init);
#endif