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AddressSanitizer.cpp
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AddressSanitizer.cpp
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/*
* Copyright (c) 2021, Brian Gianforcaro <[email protected]>
* Copyright (c) 2023, Idan Horowitz <[email protected]>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Platform.h>
#include <Kernel/Arch/Processor.h>
#include <Kernel/Boot/BootInfo.h>
#include <Kernel/KSyms.h>
#include <Kernel/Library/StdLib.h>
#include <Kernel/Security/AddressSanitizer.h>
static constexpr size_t kasan_shadow_scale_offset = 3; // We map each 8 real bytes to 1 shadow byte
static constexpr size_t kasan_shadow_scale = 1 << kasan_shadow_scale_offset;
static constexpr size_t kasan_shadow_mask = kasan_shadow_scale - 1;
// Defined in clang
static constexpr size_t kasan_alloca_redzone_size = 32;
namespace Kernel::AddressSanitizer {
enum class AccessType {
Load,
Store
};
static constexpr StringView to_string(AccessType shadow_type)
{
switch (shadow_type) {
case AccessType::Load:
return "Load"sv;
case AccessType::Store:
return "Store"sv;
default:
return "Unknown"sv;
}
}
static constexpr StringView to_string(ShadowType shadow_type)
{
switch (shadow_type) {
case ShadowType::Unpoisoned8Bytes:
return "8 Bytes Unpoisoned"sv;
case ShadowType::Unpoisoned1Byte:
return "1 Byte Unpoisoned | 7 Bytes Poisoned"sv;
case ShadowType::Unpoisoned2Bytes:
return "2 Bytes Unpoisoned | 6 Bytes Poisoned"sv;
case ShadowType::Unpoisoned3Bytes:
return "3 Bytes Unpoisoned | 5 Bytes Poisoned"sv;
case ShadowType::Unpoisoned4Bytes:
return "4 Bytes Unpoisoned | 4 Bytes Poisoned"sv;
case ShadowType::Unpoisoned5Bytes:
return "5 Bytes Unpoisoned | 3 Bytes Poisoned"sv;
case ShadowType::Unpoisoned6Bytes:
return "6 Bytes Unpoisoned | 2 Bytes Poisoned"sv;
case ShadowType::Unpoisoned7Bytes:
return "7 Bytes Unpoisoned | 1 Byte Poisoned"sv;
case ShadowType::StackLeft:
return "Stack Left Redzone"sv;
case ShadowType::StackMiddle:
return "Stack Middle Redzone"sv;
case ShadowType::StackRight:
return "Stack Right Redzone"sv;
case ShadowType::UseAfterReturn:
return "Use After Return"sv;
case ShadowType::UseAfterScope:
return "Use After Scope"sv;
case ShadowType::Generic:
return "Generic Redzone"sv;
case ShadowType::Malloc:
return "Malloc Redzone"sv;
case ShadowType::Free:
return "Freed Region"sv;
default:
return "Unknown"sv;
}
}
Atomic<bool> g_kasan_is_deadly { true };
static void print_violation(FlatPtr address, size_t size, AccessType access_type, ShadowType shadow_type, void* return_address)
{
critical_dmesgln("KASAN: Invalid {}-byte {} access to {}, which is marked as '{}' [at {:p}]", size, to_string(access_type), VirtualAddress(address), to_string(shadow_type), return_address);
dump_backtrace(g_kasan_is_deadly ? PrintToScreen::Yes : PrintToScreen::No);
if (g_kasan_is_deadly) {
critical_dmesgln("KASAN is configured to be deadly, halting the system.");
Processor::halt();
}
}
static FlatPtr kasan_shadow_base;
static FlatPtr kasan_shadow_offset;
static bool kasan_initialized = false;
void init(FlatPtr shadow_base)
{
kasan_shadow_base = shadow_base;
kasan_shadow_offset = shadow_base - (kernel_mapping_base >> kasan_shadow_scale_offset);
kasan_initialized = true;
}
static inline ShadowType* va_to_shadow(FlatPtr address)
{
return (ShadowType*)((address >> kasan_shadow_scale_offset) + kasan_shadow_offset);
}
void fill_shadow(FlatPtr address, size_t size, ShadowType type)
{
if (!kasan_initialized) [[unlikely]]
return;
VERIFY((address % kasan_shadow_scale) == 0);
VERIFY((size % kasan_shadow_scale) == 0);
auto* shadow = va_to_shadow(address);
auto shadow_size = size >> kasan_shadow_scale_offset;
memset(shadow, to_underlying(type), shadow_size);
}
void mark_region(FlatPtr address, size_t valid_size, size_t total_size, ShadowType type)
{
if (!kasan_initialized) [[unlikely]]
return;
VERIFY((address % kasan_shadow_scale) == 0);
VERIFY((total_size % kasan_shadow_scale) == 0);
auto* shadow = va_to_shadow(address);
auto valid_shadow_size = valid_size >> kasan_shadow_scale_offset;
memset(shadow, to_underlying(ShadowType::Unpoisoned8Bytes), valid_shadow_size);
auto unaligned_size = valid_size & kasan_shadow_mask;
if (unaligned_size)
*(shadow + valid_shadow_size) = static_cast<ShadowType>(unaligned_size);
auto poisoned_shadow_size = (total_size - round_up_to_power_of_two(valid_size, kasan_shadow_scale)) >> kasan_shadow_scale_offset;
memset(shadow + valid_shadow_size + (unaligned_size != 0), to_underlying(type), poisoned_shadow_size);
}
static bool shadow_va_check_1b(FlatPtr address, ShadowType& shadow_type)
{
auto const shadow = *va_to_shadow(address);
i8 const minimal_valid_shadow = (address & kasan_shadow_mask) + 1;
if (shadow == ShadowType::Unpoisoned8Bytes || (minimal_valid_shadow <= static_cast<i8>(shadow))) [[likely]]
return true;
shadow_type = shadow;
return false;
}
static bool shadow_va_check_2b(FlatPtr address, ShadowType& shadow_type)
{
// Check for unaligned access
if ((address >> kasan_shadow_scale_offset) != (address + 1) >> kasan_shadow_scale_offset) [[unlikely]]
return shadow_va_check_1b(address, shadow_type) && shadow_va_check_1b(address + 1, shadow_type);
auto const shadow = *va_to_shadow(address);
i8 const minimal_valid_shadow = ((address + 1) & kasan_shadow_mask) + 1;
if (shadow == ShadowType::Unpoisoned8Bytes || (minimal_valid_shadow <= static_cast<i8>(shadow))) [[likely]]
return true;
shadow_type = shadow;
return false;
}
static bool shadow_va_check_4b(FlatPtr address, ShadowType& shadow_type)
{
// Check for unaligned access
if ((address >> kasan_shadow_scale_offset) != (address + 3) >> kasan_shadow_scale_offset) [[unlikely]]
return shadow_va_check_2b(address, shadow_type) && shadow_va_check_2b(address + 2, shadow_type);
auto const shadow = *va_to_shadow(address);
i8 const minimal_valid_shadow = ((address + 3) & kasan_shadow_mask) + 1;
if (shadow == ShadowType::Unpoisoned8Bytes || (minimal_valid_shadow <= static_cast<i8>(shadow))) [[likely]]
return true;
shadow_type = shadow;
return false;
}
static bool shadow_va_check_8b(FlatPtr address, ShadowType& shadow_type)
{
// Check for unaligned access
if ((address >> kasan_shadow_scale_offset) != (address + 7) >> kasan_shadow_scale_offset) [[unlikely]]
return shadow_va_check_4b(address, shadow_type) && shadow_va_check_4b(address + 4, shadow_type);
auto const shadow = *va_to_shadow(address);
i8 const minimal_valid_shadow = ((address + 7) & kasan_shadow_mask) + 1;
if (shadow == ShadowType::Unpoisoned8Bytes || (minimal_valid_shadow <= static_cast<i8>(shadow))) [[likely]]
return true;
shadow_type = shadow;
return false;
}
static bool shadow_va_check_Nb(FlatPtr address, size_t n, ShadowType& shadow_type)
{
while ((address % 8) && (n > 0)) {
if (!shadow_va_check_1b(address, shadow_type)) [[unlikely]]
return false;
address++;
n--;
}
while (n >= 8) {
if (!shadow_va_check_8b(address, shadow_type))
return false;
address += 8;
n -= 8;
}
while (n > 0) {
if (!shadow_va_check_1b(address, shadow_type)) [[unlikely]]
return false;
address++;
n--;
}
return true;
}
static void shadow_va_check(FlatPtr address, size_t size, AccessType access_type, void* return_address)
{
if (size == 0) [[unlikely]]
return;
if (!kasan_initialized) [[unlikely]]
return;
if (address < kernel_mapping_base || address >= kasan_shadow_base) [[unlikely]]
return;
bool valid = false;
ShadowType shadow_type = ShadowType::Unpoisoned8Bytes;
switch (size) {
case 1:
valid = shadow_va_check_1b(address, shadow_type);
break;
case 2:
valid = shadow_va_check_2b(address, shadow_type);
break;
case 4:
valid = shadow_va_check_4b(address, shadow_type);
break;
case 8:
valid = shadow_va_check_8b(address, shadow_type);
break;
default:
valid = shadow_va_check_Nb(address, size, shadow_type);
break;
}
if (valid) [[likely]]
return;
print_violation(address, size, access_type, shadow_type, return_address);
}
}
using namespace Kernel;
using namespace Kernel::AddressSanitizer;
extern "C" {
// Define a macro to easily declare the KASAN load and store callbacks for
// the various sizes of data type.
//
#define ADDRESS_SANITIZER_LOAD_STORE(size) \
void __asan_load##size(FlatPtr); \
void __asan_load##size(FlatPtr address) \
{ \
shadow_va_check(address, size, AccessType::Load, __builtin_return_address(0)); \
} \
void __asan_load##size##_noabort(FlatPtr); \
void __asan_load##size##_noabort(FlatPtr address) \
{ \
shadow_va_check(address, size, AccessType::Load, __builtin_return_address(0)); \
} \
void __asan_store##size(FlatPtr); \
void __asan_store##size(FlatPtr address) \
{ \
shadow_va_check(address, size, AccessType::Store, __builtin_return_address(0)); \
} \
void __asan_store##size##_noabort(FlatPtr); \
void __asan_store##size##_noabort(FlatPtr address) \
{ \
shadow_va_check(address, size, AccessType::Store, __builtin_return_address(0)); \
} \
void __asan_report_load##size(FlatPtr); \
void __asan_report_load##size(FlatPtr address) \
{ \
print_violation(address, size, AccessType::Load, ShadowType::Generic, __builtin_return_address(0)); \
} \
void __asan_report_load##size##_noabort(FlatPtr); \
void __asan_report_load##size##_noabort(FlatPtr address) \
{ \
print_violation(address, size, AccessType::Load, ShadowType::Generic, __builtin_return_address(0)); \
} \
void __asan_report_store##size(FlatPtr); \
void __asan_report_store##size(FlatPtr address) \
{ \
print_violation(address, size, AccessType::Store, ShadowType::Generic, __builtin_return_address(0)); \
} \
void __asan_report_store##size##_noabort(FlatPtr); \
void __asan_report_store##size##_noabort(FlatPtr address) \
{ \
print_violation(address, size, AccessType::Store, ShadowType::Generic, __builtin_return_address(0)); \
}
ADDRESS_SANITIZER_LOAD_STORE(1);
ADDRESS_SANITIZER_LOAD_STORE(2);
ADDRESS_SANITIZER_LOAD_STORE(4);
ADDRESS_SANITIZER_LOAD_STORE(8);
ADDRESS_SANITIZER_LOAD_STORE(16);
#undef ADDRESS_SANITIZER_LOAD_STORE
void __asan_loadN(FlatPtr, size_t);
void __asan_loadN(FlatPtr address, size_t size)
{
shadow_va_check(address, size, AccessType::Load, __builtin_return_address(0));
}
void __asan_loadN_noabort(FlatPtr, size_t);
void __asan_loadN_noabort(FlatPtr address, size_t size)
{
shadow_va_check(address, size, AccessType::Load, __builtin_return_address(0));
}
void __asan_storeN(FlatPtr, size_t);
void __asan_storeN(FlatPtr address, size_t size)
{
shadow_va_check(address, size, AccessType::Store, __builtin_return_address(0));
}
void __asan_storeN_noabort(FlatPtr, size_t);
void __asan_storeN_noabort(FlatPtr address, size_t size)
{
shadow_va_check(address, size, AccessType::Store, __builtin_return_address(0));
}
void __asan_report_load_n(FlatPtr, size_t);
void __asan_report_load_n(FlatPtr address, size_t size)
{
print_violation(address, size, AccessType::Load, ShadowType::Generic, __builtin_return_address(0));
}
void __asan_report_load_n_noabort(FlatPtr, size_t);
void __asan_report_load_n_noabort(FlatPtr address, size_t size)
{
print_violation(address, size, AccessType::Load, ShadowType::Generic, __builtin_return_address(0));
}
void __asan_report_store_n(FlatPtr, size_t);
void __asan_report_store_n(FlatPtr address, size_t size)
{
print_violation(address, size, AccessType::Store, ShadowType::Generic, __builtin_return_address(0));
}
void __asan_report_store_n_noabort(FlatPtr, size_t);
void __asan_report_store_n_noabort(FlatPtr address, size_t size)
{
print_violation(address, size, AccessType::Store, ShadowType::Generic, __builtin_return_address(0));
}
// As defined in the compiler
struct __asan_global_source_location {
char const* filename;
int line_number;
int column_number;
};
struct __asan_global {
uintptr_t address;
size_t valid_size;
size_t total_size;
char const* name;
char const* module_name;
size_t has_dynamic_init;
struct __asan_global_source_location* location;
size_t odr_indicator;
};
void __asan_register_globals(struct __asan_global*, size_t);
void __asan_register_globals(struct __asan_global* globals, size_t count)
{
for (auto i = 0u; i < count; ++i)
mark_region(globals[i].address, globals[i].valid_size, globals[i].total_size, ShadowType::Generic);
}
void __asan_unregister_globals(struct __asan_global*, size_t);
void __asan_unregister_globals(struct __asan_global* globals, size_t count)
{
for (auto i = 0u; i < count; ++i)
mark_region(globals[i].address, globals[i].total_size, globals[i].total_size, ShadowType::Unpoisoned8Bytes);
}
void __asan_alloca_poison(FlatPtr, size_t);
void __asan_alloca_poison(FlatPtr address, size_t size)
{
VERIFY(address % kasan_alloca_redzone_size == 0);
auto rounded_size = round_up_to_power_of_two(size, kasan_alloca_redzone_size);
fill_shadow(address - kasan_alloca_redzone_size, kasan_alloca_redzone_size, ShadowType::StackLeft);
mark_region(address, size, rounded_size, Kernel::AddressSanitizer::ShadowType::StackMiddle);
fill_shadow(address + rounded_size, kasan_alloca_redzone_size, Kernel::AddressSanitizer::ShadowType::StackRight);
}
void __asan_allocas_unpoison(FlatPtr, size_t);
void __asan_allocas_unpoison(FlatPtr start, size_t end)
{
VERIFY(start >= end);
auto size = end - start;
VERIFY(size % kasan_shadow_scale == 0);
fill_shadow(start, size, Kernel::AddressSanitizer::ShadowType::Unpoisoned8Bytes);
}
void __asan_poison_stack_memory(FlatPtr, size_t);
void __asan_poison_stack_memory(FlatPtr address, size_t size)
{
fill_shadow(address, round_up_to_power_of_two(size, kasan_shadow_scale), Kernel::AddressSanitizer::ShadowType::UseAfterScope);
}
void __asan_unpoison_stack_memory(FlatPtr, size_t);
void __asan_unpoison_stack_memory(FlatPtr address, size_t size)
{
fill_shadow(address, round_up_to_power_of_two(size, kasan_shadow_scale), Kernel::AddressSanitizer::ShadowType::Unpoisoned8Bytes);
}
void __asan_handle_no_return(void);
void __asan_handle_no_return(void)
{
}
void __asan_before_dynamic_init(char const*);
void __asan_before_dynamic_init(char const*)
{
}
void __asan_after_dynamic_init();
void __asan_after_dynamic_init()
{
}
}