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// SPDX-License-Identifier: GPL-2.0
/*
* This file contains core generic KASAN code.
*
* Copyright (c) 2014 Samsung Electronics Co., Ltd.
* Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
*
* Some code borrowed from https://github.com/xairy/kasan-prototype by
* Andrey Konovalov <andreyknvl@gmail.com>
*/
#include <linux/export.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/kasan.h>
#include <linux/kernel.h>
#include <linux/kfence.h>
#include <linux/kmemleak.h>
#include <linux/linkage.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/sched/task_stack.h>
#include <linux/slab.h>
#include <linux/stacktrace.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/vmalloc.h>
#include <linux/bug.h>
#include "kasan.h"
#include "../slab.h"
/*
* 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_GRANULE_MASK;
return unlikely(last_accessible_byte >= shadow_value);
}
return false;
}
static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr,
unsigned long size)
{
u8 *shadow_addr = (u8 *)kasan_mem_to_shadow((void *)addr);
/*
* Access crosses 8(shadow size)-byte boundary. Such access maps
* into 2 shadow bytes, so we need to check them both.
*/
if (unlikely(((addr + size - 1) & KASAN_GRANULE_MASK) < size - 1))
return *shadow_addr || memory_is_poisoned_1(addr + size - 1);
return memory_is_poisoned_1(addr + size - 1);
}
static __always_inline bool memory_is_poisoned_16(unsigned long addr)
{
u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
/* Unaligned 16-bytes access maps into 3 shadow bytes. */
if (unlikely(!IS_ALIGNED(addr, KASAN_GRANULE_SIZE)))
return *shadow_addr || memory_is_poisoned_1(addr + 15);
return *shadow_addr;
}
static __always_inline unsigned long bytes_is_nonzero(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_nonzero(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_nonzero(start, end - start);
if (prefix) {
prefix = 8 - prefix;
ret = bytes_is_nonzero(start, prefix);
if (unlikely(ret))
return ret;
start += prefix;
}
words = (end - start) / 8;
while (words) {
if (unlikely(*(u64 *)start))
return bytes_is_nonzero(start, 8);
start += 8;
words--;
}
return bytes_is_nonzero(start, (end - start) % 8);
}
static __always_inline bool memory_is_poisoned_n(unsigned long addr,
size_t size)
{
unsigned long ret;
ret = memory_is_nonzero(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 ||
((long)(last_byte & KASAN_GRANULE_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:
case 4:
case 8:
return memory_is_poisoned_2_4_8(addr, size);
case 16:
return memory_is_poisoned_16(addr);
default:
BUILD_BUG();
}
}
return memory_is_poisoned_n(addr, size);
}
static __always_inline bool check_region_inline(unsigned long addr,
size_t size, bool write,
unsigned long ret_ip)
{
if (!kasan_arch_is_ready())
return true;
if (unlikely(size == 0))
return true;
if (unlikely(addr + size < addr))
return !kasan_report(addr, size, write, ret_ip);
if (unlikely((void *)addr <
kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
return !kasan_report(addr, size, write, ret_ip);
}
if (likely(!memory_is_poisoned(addr, size)))
return true;
return !kasan_report(addr, size, write, ret_ip);
}
bool kasan_check_range(unsigned long addr, size_t size, bool write,
unsigned long ret_ip)
{
return check_region_inline(addr, size, write, ret_ip);
}
bool kasan_byte_accessible(const void *addr)
{
s8 shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(addr));
return shadow_byte >= 0 && shadow_byte < KASAN_GRANULE_SIZE;
}
void kasan_cache_shrink(struct kmem_cache *cache)
{
kasan_quarantine_remove_cache(cache);
}
void kasan_cache_shutdown(struct kmem_cache *cache)
{
if (!__kmem_cache_empty(cache))
kasan_quarantine_remove_cache(cache);
}
static void register_global(struct kasan_global *global)
{
size_t aligned_size = round_up(global->size, KASAN_GRANULE_SIZE);
kasan_unpoison(global->beg, global->size, false);
kasan_poison(global->beg + aligned_size,
global->size_with_redzone - aligned_size,
KASAN_GLOBAL_REDZONE, false);
}
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_region_inline(addr, size, false, _RET_IP_); \
} \
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_region_inline(addr, size, true, _RET_IP_); \
} \
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)
{
kasan_check_range(addr, size, false, _RET_IP_);
}
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)
{
kasan_check_range(addr, size, true, _RET_IP_);
}
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);
/* Emitted by compiler to poison alloca()ed objects. */
void __asan_alloca_poison(unsigned long addr, size_t size)
{
size_t rounded_up_size = round_up(size, KASAN_GRANULE_SIZE);
size_t padding_size = round_up(size, KASAN_ALLOCA_REDZONE_SIZE) -
rounded_up_size;
size_t rounded_down_size = round_down(size, KASAN_GRANULE_SIZE);
const void *left_redzone = (const void *)(addr -
KASAN_ALLOCA_REDZONE_SIZE);
const void *right_redzone = (const void *)(addr + rounded_up_size);
WARN_ON(!IS_ALIGNED(addr, KASAN_ALLOCA_REDZONE_SIZE));
kasan_unpoison((const void *)(addr + rounded_down_size),
size - rounded_down_size, false);
kasan_poison(left_redzone, KASAN_ALLOCA_REDZONE_SIZE,
KASAN_ALLOCA_LEFT, false);
kasan_poison(right_redzone, padding_size + KASAN_ALLOCA_REDZONE_SIZE,
KASAN_ALLOCA_RIGHT, false);
}
EXPORT_SYMBOL(__asan_alloca_poison);
/* Emitted by compiler to unpoison alloca()ed areas when the stack unwinds. */
void __asan_allocas_unpoison(const void *stack_top, const void *stack_bottom)
{
if (unlikely(!stack_top || stack_top > stack_bottom))
return;
kasan_unpoison(stack_top, stack_bottom - stack_top, false);
}
EXPORT_SYMBOL(__asan_allocas_unpoison);
/* Emitted by the compiler to [un]poison local variables. */
#define DEFINE_ASAN_SET_SHADOW(byte) \
void __asan_set_shadow_##byte(const void *addr, size_t size) \
{ \
__memset((void *)addr, 0x##byte, size); \
} \
EXPORT_SYMBOL(__asan_set_shadow_##byte)
DEFINE_ASAN_SET_SHADOW(00);
DEFINE_ASAN_SET_SHADOW(f1);
DEFINE_ASAN_SET_SHADOW(f2);
DEFINE_ASAN_SET_SHADOW(f3);
DEFINE_ASAN_SET_SHADOW(f5);
DEFINE_ASAN_SET_SHADOW(f8);
static void __kasan_record_aux_stack(void *addr, bool can_alloc)
{
struct slab *slab = kasan_addr_to_slab(addr);
struct kmem_cache *cache;
struct kasan_alloc_meta *alloc_meta;
void *object;
if (is_kfence_address(addr) || !slab)
return;
cache = slab->slab_cache;
object = nearest_obj(cache, slab, addr);
alloc_meta = kasan_get_alloc_meta(cache, object);
if (!alloc_meta)
return;
alloc_meta->aux_stack[1] = alloc_meta->aux_stack[0];
alloc_meta->aux_stack[0] = kasan_save_stack(GFP_NOWAIT, can_alloc);
}
void kasan_record_aux_stack(void *addr)
{
return __kasan_record_aux_stack(addr, true);
}
void kasan_record_aux_stack_noalloc(void *addr)
{
return __kasan_record_aux_stack(addr, false);
}
void kasan_set_free_info(struct kmem_cache *cache,
void *object, u8 tag)
{
struct kasan_free_meta *free_meta;
free_meta = kasan_get_free_meta(cache, object);
if (!free_meta)
return;
kasan_set_track(&free_meta->free_track, GFP_NOWAIT);
/* The object was freed and has free track set. */
*(u8 *)kasan_mem_to_shadow(object) = KASAN_KMALLOC_FREETRACK;
}
struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
void *object, u8 tag)
{
if (*(u8 *)kasan_mem_to_shadow(object) != KASAN_KMALLOC_FREETRACK)
return NULL;
/* Free meta must be present with KASAN_KMALLOC_FREETRACK. */
return &kasan_get_free_meta(cache, object)->free_track;
}