[linux-2.6-block.git] / mm / kasan / generic.c

// 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>
 *
 * 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/interrupt.h>
#include <linux/init.h>
#include <linux/kasan.h>
#include <linux/kernel.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_SHADOW_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_SHADOW_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_SHADOW_SCALE_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_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:
		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_memory_region_inline(unsigned long addr,
						size_t size, bool write,
						unsigned long ret_ip)
{
	if (unlikely(size == 0))
		return true;

	if (unlikely((void *)addr <
		kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
		kasan_report(addr, size, write, ret_ip);
		return false;
	}

	if (likely(!memory_is_poisoned(addr, size)))
		return true;

	kasan_report(addr, size, write, ret_ip);
	return false;
}

bool check_memory_region(unsigned long addr, size_t size, bool write,
				unsigned long ret_ip)
{
	return check_memory_region_inline(addr, size, write, ret_ip);
}

void kasan_cache_shrink(struct kmem_cache *cache)
{
	quarantine_remove_cache(cache);
}

void kasan_cache_shutdown(struct kmem_cache *cache)
{
	if (!__kmem_cache_empty(cache))
		quarantine_remove_cache(cache);
}

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_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_memory_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)
{
	check_memory_region(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)
{
	check_memory_region(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_SHADOW_SCALE_SIZE);
	size_t padding_size = round_up(size, KASAN_ALLOCA_REDZONE_SIZE) -
			rounded_up_size;
	size_t rounded_down_size = round_down(size, KASAN_SHADOW_SCALE_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_shadow((const void *)(addr + rounded_down_size),
			      size - rounded_down_size);
	kasan_poison_shadow(left_redzone, KASAN_ALLOCA_REDZONE_SIZE,
			KASAN_ALLOCA_LEFT);
	kasan_poison_shadow(right_redzone,
			padding_size + KASAN_ALLOCA_REDZONE_SIZE,
			KASAN_ALLOCA_RIGHT);
}
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_shadow(stack_top, stack_bottom - stack_top);
}
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);
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* This file contains core generic KASAN code.
	4	*
	5	* Copyright (c) 2014 Samsung Electronics Co., Ltd.
	6	* Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
	7	*
	8	* Some code borrowed from https://github.com/xairy/kasan-prototype by
	9	* Andrey Konovalov <andreyknvl@gmail.com>
	10	*
	11	* This program is free software; you can redistribute it and/or modify
	12	* it under the terms of the GNU General Public License version 2 as
	13	* published by the Free Software Foundation.
	14	*
	15	*/
	16
	17	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	18	#define DISABLE_BRANCH_PROFILING
	19
	20	#include <linux/export.h>
	21	#include <linux/interrupt.h>
	22	#include <linux/init.h>
	23	#include <linux/kasan.h>
	24	#include <linux/kernel.h>
	25	#include <linux/kmemleak.h>
	26	#include <linux/linkage.h>
	27	#include <linux/memblock.h>
	28	#include <linux/memory.h>
	29	#include <linux/mm.h>
	30	#include <linux/module.h>
	31	#include <linux/printk.h>
	32	#include <linux/sched.h>
	33	#include <linux/sched/task_stack.h>
	34	#include <linux/slab.h>
	35	#include <linux/stacktrace.h>
	36	#include <linux/string.h>
	37	#include <linux/types.h>
	38	#include <linux/vmalloc.h>
	39	#include <linux/bug.h>
	40
	41	#include "kasan.h"
	42	#include "../slab.h"
	43
	44	/*
	45	* All functions below always inlined so compiler could
	46	* perform better optimizations in each of __asan_loadX/__assn_storeX
	47	* depending on memory access size X.
	48	*/
	49
	50	static __always_inline bool memory_is_poisoned_1(unsigned long addr)
	51	{
	52	s8 shadow_value = (s8 )kasan_mem_to_shadow((void *)addr);
	53
	54	if (unlikely(shadow_value)) {
	55	s8 last_accessible_byte = addr & KASAN_SHADOW_MASK;
	56	return unlikely(last_accessible_byte >= shadow_value);
	57	}
	58
	59	return false;
	60	}
	61
	62	static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr,
	63	unsigned long size)
	64	{
	65	u8 shadow_addr = (u8 )kasan_mem_to_shadow((void *)addr);
	66
	67	/*
	68	* Access crosses 8(shadow size)-byte boundary. Such access maps
	69	* into 2 shadow bytes, so we need to check them both.
	70	*/
	71	if (unlikely(((addr + size - 1) & KASAN_SHADOW_MASK) < size - 1))
	72	return *shadow_addr \|\| memory_is_poisoned_1(addr + size - 1);
	73
	74	return memory_is_poisoned_1(addr + size - 1);
	75	}
	76
	77	static __always_inline bool memory_is_poisoned_16(unsigned long addr)
	78	{
	79	u16 shadow_addr = (u16 )kasan_mem_to_shadow((void *)addr);
	80
	81	/* Unaligned 16-bytes access maps into 3 shadow bytes. */
	82	if (unlikely(!IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
	83	return *shadow_addr \|\| memory_is_poisoned_1(addr + 15);
	84
	85	return *shadow_addr;
	86	}
	87
	88	static __always_inline unsigned long bytes_is_nonzero(const u8 *start,
	89	size_t size)
	90	{
	91	while (size) {
	92	if (unlikely(*start))
	93	return (unsigned long)start;
	94	start++;
	95	size--;
	96	}
	97
	98	return 0;
	99	}
	100
	101	static __always_inline unsigned long memory_is_nonzero(const void *start,
	102	const void *end)
	103	{
	104	unsigned int words;
	105	unsigned long ret;
	106	unsigned int prefix = (unsigned long)start % 8;
	107
	108	if (end - start <= 16)
	109	return bytes_is_nonzero(start, end - start);
	110
	111	if (prefix) {
	112	prefix = 8 - prefix;
	113	ret = bytes_is_nonzero(start, prefix);
	114	if (unlikely(ret))
	115	return ret;
	116	start += prefix;
	117	}
	118
	119	words = (end - start) / 8;
	120	while (words) {
	121	if (unlikely((u64 )start))
	122	return bytes_is_nonzero(start, 8);
	123	start += 8;
	124	words--;
	125	}
	126
	127	return bytes_is_nonzero(start, (end - start) % 8);
	128	}
	129
	130	static __always_inline bool memory_is_poisoned_n(unsigned long addr,
	131	size_t size)
	132	{
	133	unsigned long ret;
	134
	135	ret = memory_is_nonzero(kasan_mem_to_shadow((void *)addr),
	136	kasan_mem_to_shadow((void *)addr + size - 1) + 1);
	137
	138	if (unlikely(ret)) {
	139	unsigned long last_byte = addr + size - 1;
	140	s8 last_shadow = (s8 )kasan_mem_to_shadow((void *)last_byte);
	141
	142	if (unlikely(ret != (unsigned long)last_shadow \|\|
	143	((long)(last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
	144	return true;
	145	}
	146	return false;
	147	}
	148
	149	static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
	150	{
	151	if (__builtin_constant_p(size)) {
	152	switch (size) {
	153	case 1:
	154	return memory_is_poisoned_1(addr);
	155	case 2:
	156	case 4:
	157	case 8:
	158	return memory_is_poisoned_2_4_8(addr, size);
	159	case 16:
	160	return memory_is_poisoned_16(addr);
	161	default:
	162	BUILD_BUG();
	163	}
	164	}
	165
	166	return memory_is_poisoned_n(addr, size);
	167	}
	168
	169	static __always_inline bool check_memory_region_inline(unsigned long addr,
	170	size_t size, bool write,
	171	unsigned long ret_ip)
	172	{
	173	if (unlikely(size == 0))
	174	return true;
	175
	176	if (unlikely((void *)addr <
	177	kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
	178	kasan_report(addr, size, write, ret_ip);
	179	return false;
	180	}
	181
	182	if (likely(!memory_is_poisoned(addr, size)))
	183	return true;
	184
	185	kasan_report(addr, size, write, ret_ip);
	186	return false;
	187	}
	188
	189	bool check_memory_region(unsigned long addr, size_t size, bool write,
	190	unsigned long ret_ip)
	191	{
	192	return check_memory_region_inline(addr, size, write, ret_ip);
	193	}
	194
	195	void kasan_cache_shrink(struct kmem_cache *cache)
	196	{
	197	quarantine_remove_cache(cache);
	198	}
	199
	200	void kasan_cache_shutdown(struct kmem_cache *cache)
	201	{
	202	if (!__kmem_cache_empty(cache))
	203	quarantine_remove_cache(cache);
	204	}
	205
	206	static void register_global(struct kasan_global *global)
	207	{
	208	size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
	209
	210	kasan_unpoison_shadow(global->beg, global->size);
	211
	212	kasan_poison_shadow(global->beg + aligned_size,
	213	global->size_with_redzone - aligned_size,
	214	KASAN_GLOBAL_REDZONE);
	215	}
	216
	217	void __asan_register_globals(struct kasan_global *globals, size_t size)
	218	{
	219	int i;
	220
	221	for (i = 0; i < size; i++)
	222	register_global(&globals[i]);
	223	}
	224	EXPORT_SYMBOL(__asan_register_globals);
	225
	226	void __asan_unregister_globals(struct kasan_global *globals, size_t size)
	227	{
	228	}
	229	EXPORT_SYMBOL(__asan_unregister_globals);
	230
	231	#define DEFINE_ASAN_LOAD_STORE(size) \
	232	void __asan_load##size(unsigned long addr) \
	233	{ \
	234	check_memory_region_inline(addr, size, false, _RET_IP_);\
	235	} \
	236	EXPORT_SYMBOL(__asan_load##size); \
	237	__alias(__asan_load##size) \
	238	void __asan_load##size##_noabort(unsigned long); \
	239	EXPORT_SYMBOL(__asan_load##size##_noabort); \
	240	void __asan_store##size(unsigned long addr) \
	241	{ \
	242	check_memory_region_inline(addr, size, true, _RET_IP_); \
	243	} \
	244	EXPORT_SYMBOL(__asan_store##size); \
	245	__alias(__asan_store##size) \
	246	void __asan_store##size##_noabort(unsigned long); \
	247	EXPORT_SYMBOL(__asan_store##size##_noabort)
	248
	249	DEFINE_ASAN_LOAD_STORE(1);
	250	DEFINE_ASAN_LOAD_STORE(2);
	251	DEFINE_ASAN_LOAD_STORE(4);
	252	DEFINE_ASAN_LOAD_STORE(8);
	253	DEFINE_ASAN_LOAD_STORE(16);
	254
	255	void __asan_loadN(unsigned long addr, size_t size)
	256	{
	257	check_memory_region(addr, size, false, _RET_IP_);
	258	}
	259	EXPORT_SYMBOL(__asan_loadN);
	260
	261	__alias(__asan_loadN)
	262	void __asan_loadN_noabort(unsigned long, size_t);
	263	EXPORT_SYMBOL(__asan_loadN_noabort);
	264
	265	void __asan_storeN(unsigned long addr, size_t size)
	266	{
	267	check_memory_region(addr, size, true, _RET_IP_);
	268	}
	269	EXPORT_SYMBOL(__asan_storeN);
	270
	271	__alias(__asan_storeN)
	272	void __asan_storeN_noabort(unsigned long, size_t);
	273	EXPORT_SYMBOL(__asan_storeN_noabort);
	274
	275	/* to shut up compiler complaints */
	276	void __asan_handle_no_return(void) {}
	277	EXPORT_SYMBOL(__asan_handle_no_return);
	278
	279	/* Emitted by compiler to poison alloca()ed objects. */
	280	void __asan_alloca_poison(unsigned long addr, size_t size)
	281	{
	282	size_t rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
	283	size_t padding_size = round_up(size, KASAN_ALLOCA_REDZONE_SIZE) -
	284	rounded_up_size;
	285	size_t rounded_down_size = round_down(size, KASAN_SHADOW_SCALE_SIZE);
	286
	287	const void left_redzone = (const void )(addr -
	288	KASAN_ALLOCA_REDZONE_SIZE);
	289	const void right_redzone = (const void )(addr + rounded_up_size);
	290
	291	WARN_ON(!IS_ALIGNED(addr, KASAN_ALLOCA_REDZONE_SIZE));
	292
	293	kasan_unpoison_shadow((const void *)(addr + rounded_down_size),
	294	size - rounded_down_size);
	295	kasan_poison_shadow(left_redzone, KASAN_ALLOCA_REDZONE_SIZE,
	296	KASAN_ALLOCA_LEFT);
	297	kasan_poison_shadow(right_redzone,
	298	padding_size + KASAN_ALLOCA_REDZONE_SIZE,
	299	KASAN_ALLOCA_RIGHT);
	300	}
	301	EXPORT_SYMBOL(__asan_alloca_poison);
	302
	303	/* Emitted by compiler to unpoison alloca()ed areas when the stack unwinds. */
	304	void __asan_allocas_unpoison(const void stack_top, const void stack_bottom)
	305	{
	306	if (unlikely(!stack_top \|\| stack_top > stack_bottom))
	307	return;
	308
	309	kasan_unpoison_shadow(stack_top, stack_bottom - stack_top);
	310	}
	311	EXPORT_SYMBOL(__asan_allocas_unpoison);
	312
	313	/* Emitted by the compiler to [un]poison local variables. */
	314	#define DEFINE_ASAN_SET_SHADOW(byte) \
	315	void __asan_set_shadow_##byte(const void *addr, size_t size) \
	316	{ \
	317	__memset((void *)addr, 0x##byte, size); \
	318	} \
	319	EXPORT_SYMBOL(__asan_set_shadow_##byte)
	320
	321	DEFINE_ASAN_SET_SHADOW(00);
	322	DEFINE_ASAN_SET_SHADOW(f1);
	323	DEFINE_ASAN_SET_SHADOW(f2);
	324	DEFINE_ASAN_SET_SHADOW(f3);
	325	DEFINE_ASAN_SET_SHADOW(f5);
	326	DEFINE_ASAN_SET_SHADOW(f8);