// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#include "core/file_sys/fssystem/fssystem_aes_ctr_counter_extended_storage.h"
#include "core/file_sys/fssystem/fssystem_aes_ctr_storage.h"
#include "core/file_sys/fssystem/fssystem_nca_header.h"
#include "core/file_sys/vfs_offset.h"
namespace FileSys {
namespace {
class SoftwareDecryptor final : public AesCtrCounterExtendedStorage::IDecryptor {
public:
virtual void Decrypt(
u8* buf, size_t buf_size, const std::array<u8, AesCtrCounterExtendedStorage::KeySize>& key,
const std::array<u8, AesCtrCounterExtendedStorage::IvSize>& iv) override final;
};
} // namespace
Result AesCtrCounterExtendedStorage::CreateSoftwareDecryptor(std::unique_ptr<IDecryptor>* out) {
std::unique_ptr<IDecryptor> decryptor = std::make_unique<SoftwareDecryptor>();
R_UNLESS(decryptor != nullptr, ResultAllocationMemoryFailedInAesCtrCounterExtendedStorageA);
*out = std::move(decryptor);
R_SUCCEED();
}
Result AesCtrCounterExtendedStorage::Initialize(const void* key, size_t key_size, u32 secure_value,
VirtualFile data_storage,
VirtualFile table_storage) {
// Read and verify the bucket tree header.
BucketTree::Header header;
table_storage->ReadObject(std::addressof(header), 0);
R_TRY(header.Verify());
// Determine extents.
const auto node_storage_size = QueryNodeStorageSize(header.entry_count);
const auto entry_storage_size = QueryEntryStorageSize(header.entry_count);
const auto node_storage_offset = QueryHeaderStorageSize();
const auto entry_storage_offset = node_storage_offset + node_storage_size;
// Create a software decryptor.
std::unique_ptr<IDecryptor> sw_decryptor;
R_TRY(CreateSoftwareDecryptor(std::addressof(sw_decryptor)));
// Initialize.
R_RETURN(this->Initialize(
key, key_size, secure_value, 0, data_storage,
std::make_shared<OffsetVfsFile>(table_storage, node_storage_size, node_storage_offset),
std::make_shared<OffsetVfsFile>(table_storage, entry_storage_size, entry_storage_offset),
header.entry_count, std::move(sw_decryptor)));
}
Result AesCtrCounterExtendedStorage::Initialize(const void* key, size_t key_size, u32 secure_value,
s64 counter_offset, VirtualFile data_storage,
VirtualFile node_storage, VirtualFile entry_storage,
s32 entry_count,
std::unique_ptr<IDecryptor>&& decryptor) {
// Validate preconditions.
ASSERT(key != nullptr);
ASSERT(key_size == KeySize);
ASSERT(counter_offset >= 0);
ASSERT(decryptor != nullptr);
// Initialize the bucket tree table.
if (entry_count > 0) {
R_TRY(
m_table.Initialize(node_storage, entry_storage, NodeSize, sizeof(Entry), entry_count));
} else {
m_table.Initialize(NodeSize, 0);
}
// Set members.
m_data_storage = data_storage;
std::memcpy(m_key.data(), key, key_size);
m_secure_value = secure_value;
m_counter_offset = counter_offset;
m_decryptor = std::move(decryptor);
R_SUCCEED();
}
void AesCtrCounterExtendedStorage::Finalize() {
if (this->IsInitialized()) {
m_table.Finalize();
m_data_storage = VirtualFile();
}
}
Result AesCtrCounterExtendedStorage::GetEntryList(Entry* out_entries, s32* out_entry_count,
s32 entry_count, s64 offset, s64 size) {
// Validate pre-conditions.
ASSERT(offset >= 0);
ASSERT(size >= 0);
ASSERT(this->IsInitialized());
// Clear the out count.
R_UNLESS(out_entry_count != nullptr, ResultNullptrArgument);
*out_entry_count = 0;
// Succeed if there's no range.
R_SUCCEED_IF(size == 0);
// If we have an output array, we need it to be non-null.
R_UNLESS(out_entries != nullptr || entry_count == 0, ResultNullptrArgument);
// Check that our range is valid.
BucketTree::Offsets table_offsets;
R_TRY(m_table.GetOffsets(std::addressof(table_offsets)));
R_UNLESS(table_offsets.IsInclude(offset, size), ResultOutOfRange);
// Find the offset in our tree.
BucketTree::Visitor visitor;
R_TRY(m_table.Find(std::addressof(visitor), offset));
{
const auto entry_offset = visitor.Get<Entry>()->GetOffset();
R_UNLESS(0 <= entry_offset && table_offsets.IsInclude(entry_offset),
ResultInvalidAesCtrCounterExtendedEntryOffset);
}
// Prepare to loop over entries.
const auto end_offset = offset + static_cast<s64>(size);
s32 count = 0;
auto cur_entry = *visitor.Get<Entry>();
while (cur_entry.GetOffset() < end_offset) {
// Try to write the entry to the out list.
if (entry_count != 0) {
if (count >= entry_count) {
break;
}
std::memcpy(out_entries + count, std::addressof(cur_entry), sizeof(Entry));
}
count++;
// Advance.
if (visitor.CanMoveNext()) {
R_TRY(visitor.MoveNext());
cur_entry = *visitor.Get<Entry>();
} else {
break;
}
}
// Write the output count.
*out_entry_count = count;
R_SUCCEED();
}
size_t AesCtrCounterExtendedStorage::Read(u8* buffer, size_t size, size_t offset) const {
// Validate preconditions.
ASSERT(this->IsInitialized());
// Allow zero size.
if (size == 0) {
return size;
}
// Validate arguments.
ASSERT(buffer != nullptr);
ASSERT(Common::IsAligned(offset, BlockSize));
ASSERT(Common::IsAligned(size, BlockSize));
BucketTree::Offsets table_offsets;
ASSERT(R_SUCCEEDED(m_table.GetOffsets(std::addressof(table_offsets))));
ASSERT(table_offsets.IsInclude(offset, size));
// Read the data.
m_data_storage->Read(buffer, size, offset);
// Find the offset in our tree.
BucketTree::Visitor visitor;
ASSERT(R_SUCCEEDED(m_table.Find(std::addressof(visitor), offset)));
{
const auto entry_offset = visitor.Get<Entry>()->GetOffset();
ASSERT(Common::IsAligned(entry_offset, BlockSize));
ASSERT(0 <= entry_offset && table_offsets.IsInclude(entry_offset));
}
// Prepare to read in chunks.
u8* cur_data = static_cast<u8*>(buffer);
auto cur_offset = offset;
const auto end_offset = offset + static_cast<s64>(size);
while (cur_offset < end_offset) {
// Get the current entry.
const auto cur_entry = *visitor.Get<Entry>();
// Get and validate the entry's offset.
const auto cur_entry_offset = cur_entry.GetOffset();
ASSERT(static_cast<size_t>(cur_entry_offset) <= cur_offset);
// Get and validate the next entry offset.
s64 next_entry_offset;
if (visitor.CanMoveNext()) {
ASSERT(R_SUCCEEDED(visitor.MoveNext()));
next_entry_offset = visitor.Get<Entry>()->GetOffset();
ASSERT(table_offsets.IsInclude(next_entry_offset));
} else {
next_entry_offset = table_offsets.end_offset;
}
ASSERT(Common::IsAligned(next_entry_offset, BlockSize));
ASSERT(cur_offset < static_cast<size_t>(next_entry_offset));
// Get the offset of the entry in the data we read.
const auto data_offset = cur_offset - cur_entry_offset;
const auto data_size = (next_entry_offset - cur_entry_offset) - data_offset;
ASSERT(data_size > 0);
// Determine how much is left.
const auto remaining_size = end_offset - cur_offset;
const auto cur_size = static_cast<size_t>(std::min(remaining_size, data_size));
ASSERT(cur_size <= size);
// If necessary, perform decryption.
if (cur_entry.encryption_value == Entry::Encryption::Encrypted) {
// Make the CTR for the data we're decrypting.
const auto counter_offset = m_counter_offset + cur_entry_offset + data_offset;
NcaAesCtrUpperIv upper_iv = {
.part = {.generation = static_cast<u32>(cur_entry.generation),
.secure_value = m_secure_value}};
std::array<u8, IvSize> iv;
AesCtrStorage::MakeIv(iv.data(), IvSize, upper_iv.value, counter_offset);
// Decrypt.
m_decryptor->Decrypt(cur_data, cur_size, m_key, iv);
}
// Advance.
cur_data += cur_size;
cur_offset += cur_size;
}
return size;
}
void SoftwareDecryptor::Decrypt(u8* buf, size_t buf_size,
const std::array<u8, AesCtrCounterExtendedStorage::KeySize>& key,
const std::array<u8, AesCtrCounterExtendedStorage::IvSize>& iv) {
Core::Crypto::AESCipher<Core::Crypto::Key128, AesCtrCounterExtendedStorage::KeySize> cipher(
key, Core::Crypto::Mode::CTR);
cipher.SetIV(iv);
cipher.Transcode(buf, buf_size, buf, Core::Crypto::Op::Decrypt);
}
} // namespace FileSys
