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[core/loader] Implement a bit improper ASLR (#2945) 

A bit improper of an ASLR - it does something but something good? Who knows...
All I know is that there is a non-uniform distrobution for rand() and that rng_seed is likely a better solution?
I don't know

Signed-off-by: lizzie lizzie@eden-emu.dev

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/2945
Reviewed-by: Maufeat <sahyno1996@gmail.com>
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Co-authored-by: lizzie <lizzie@eden-emu.dev>
Co-committed-by: lizzie <lizzie@eden-emu.dev>
This commit is contained in:
lizzie 2025-11-04 22:35:34 +01:00 committed by crueter
parent 6abaee94a6
commit 504df4856d
No known key found for this signature in database
GPG Key ID: 425ACD2D4830EBC6
5 changed files with 34 additions and 19 deletions
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16
src/core/hle/kernel/k_process.cpp
View File

@ -28,9 +28,6 @@ namespace Kernel {
namespace {
// TODO: Remove this workaround when proper ASLR is implemented for all address spaces.
constexpr u64 CodeStartOffset = 0x500000UL;
Result TerminateChildren(KernelCore& kernel, KProcess* process,
const KThread* thread_to_not_terminate) {
// Request that all children threads terminate.
@ -1157,7 +1154,7 @@ KProcess::KProcess(KernelCore& kernel)
KProcess::~KProcess() = default;
Result KProcess::LoadFromMetadata(const FileSys::ProgramMetadata& metadata, std::size_t code_size,
KProcessAddress aslr_space_start, bool is_hbl) {
KProcessAddress aslr_space_start, size_t aslr_space_offset, bool is_hbl) {
// Create a resource limit for the process.
const auto pool = static_cast<KMemoryManager::Pool>(metadata.GetPoolPartition());
const auto physical_memory_size = m_kernel.MemoryManager().GetSize(pool);
@ -1187,25 +1184,24 @@ Result KProcess::LoadFromMetadata(const FileSys::ProgramMetadata& metadata, std:
// Set the address space type and code address.
switch (metadata.GetAddressSpaceType()) {
case FileSys::ProgramAddressSpaceType::Is39Bit:
flag |= Svc::CreateProcessFlag::AddressSpace64Bit;
// For 39-bit processes, the ASLR region starts at 0x800'0000 and is ~512GiB large.
// However, some (buggy) programs/libraries like skyline incorrectly depend on the
// existence of ASLR pages before the entry point, so we will adjust the load address
// to point to about 2GiB into the ASLR region.
code_address = 0x8000'0000;
flag |= Svc::CreateProcessFlag::AddressSpace64Bit;
code_address = 0x8000'0000 + aslr_space_offset;
break;
case FileSys::ProgramAddressSpaceType::Is36Bit:
flag |= Svc::CreateProcessFlag::AddressSpace64BitDeprecated;
code_address = 0x800'0000;
code_address = 0x800'0000 + aslr_space_offset;
break;
case FileSys::ProgramAddressSpaceType::Is32Bit:
flag |= Svc::CreateProcessFlag::AddressSpace32Bit;
code_address = 0x20'0000 + CodeStartOffset;
code_address = 0x20'0000 + aslr_space_offset;
break;
case FileSys::ProgramAddressSpaceType::Is32BitNoMap:
flag |= Svc::CreateProcessFlag::AddressSpace32BitWithoutAlias;
code_address = 0x20'0000 + CodeStartOffset;
code_address = 0x20'0000 + aslr_space_offset;
break;
}

2
src/core/hle/kernel/k_process.h
View File

@ -511,7 +511,7 @@ public:
public:
Result LoadFromMetadata(const FileSys::ProgramMetadata& metadata, std::size_t code_size,
KProcessAddress aslr_space_start, bool is_hbl);
KProcessAddress aslr_space_start, size_t aslr_space_offset, bool is_hbl);
void LoadModule(CodeSet code_set, KProcessAddress base_addr);

10
src/core/loader/deconstructed_rom_directory.cpp
View File

@ -1,3 +1,6 @@
// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
// SPDX-License-Identifier: GPL-3.0-or-later
// SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
@ -223,8 +226,13 @@ AppLoader_DeconstructedRomDirectory::LoadResult AppLoader_DeconstructedRomDirect
// Add patch size to the total module size
code_size += patch_ctx.GetTotalPatchSize();
// TODO: this is bad form of ASLR, it sucks
size_t aslr_offset = ((::Settings::values.rng_seed_enabled.GetValue()
? ::Settings::values.rng_seed.GetValue()
: std::rand()) * 0x734287f27) & 0xfff000;
// Setup the process code layout
if (process.LoadFromMetadata(metadata, code_size, fastmem_base, is_hbl).IsError()) {
if (process.LoadFromMetadata(metadata, code_size, fastmem_base, aslr_offset, is_hbl).IsError()) {
return {ResultStatus::ErrorUnableToParseKernelMetadata, {}};
}

14
src/core/loader/kip.cpp
View File

@ -5,6 +5,7 @@
// SPDX-License-Identifier: GPL-2.0-or-later
#include <cstring>
#include "common/settings.h"
#include "core/file_sys/kernel_executable.h"
#include "core/file_sys/program_metadata.h"
#include "core/hle/kernel/code_set.h"
@ -76,11 +77,10 @@ AppLoader::LoadResult AppLoader_KIP::Load(Kernel::KProcess& process,
Kernel::CodeSet codeset;
Kernel::PhysicalMemory program_image;
const auto load_segment = [&program_image](Kernel::CodeSet::Segment& segment,
const std::vector<u8>& data, u32 offset) {
const auto load_segment = [&program_image](Kernel::CodeSet::Segment& segment, const std::vector<u8>& data, u32 offset) {
segment.addr = offset;
segment.offset = offset;
segment.size = PageAlignSize(static_cast<u32>(data.size()));
segment.size = PageAlignSize(u32(data.size()));
program_image.resize(offset + data.size());
std::memcpy(program_image.data() + offset, data.data(), data.size());
};
@ -92,10 +92,14 @@ AppLoader::LoadResult AppLoader_KIP::Load(Kernel::KProcess& process,
program_image.resize(PageAlignSize(kip->GetBSSOffset()) + kip->GetBSSSize());
codeset.DataSegment().size += kip->GetBSSSize();
// TODO: this is bad form of ASLR, it sucks
size_t aslr_offset = ((::Settings::values.rng_seed_enabled.GetValue()
? ::Settings::values.rng_seed.GetValue()
: std::rand()) * 0x734287f27) & 0xfff000;
// Setup the process code layout
if (process
.LoadFromMetadata(FileSys::ProgramMetadata::GetDefault(), program_image.size(), 0,
false)
.LoadFromMetadata(FileSys::ProgramMetadata::GetDefault(), program_image.size(), 0, aslr_offset, false)
.IsError()) {
return {ResultStatus::ErrorNotInitialized, {}};
}

11
src/core/loader/nro.cpp
View File

@ -1,3 +1,6 @@
// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
// SPDX-License-Identifier: GPL-3.0-or-later
// SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
@ -237,10 +240,14 @@ static bool LoadNroImpl(Core::System& system, Kernel::KProcess& process,
return 0;
}();
// TODO: this is bad form of ASLR, it sucks
size_t aslr_offset = ((::Settings::values.rng_seed_enabled.GetValue()
? ::Settings::values.rng_seed.GetValue()
: std::rand()) * 0x734287f27) & 0xfff000;
// Setup the process code layout
if (process
.LoadFromMetadata(FileSys::ProgramMetadata::GetDefault(), image_size, fastmem_base,
false)
.LoadFromMetadata(FileSys::ProgramMetadata::GetDefault(), image_size, fastmem_base, aslr_offset, false)
.IsError()) {
return false;
}