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// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#include "common/alignment.h"
#include "common/swap.h"
#include "core/file_sys/errors.h"
#include "core/file_sys/fssystem/fssystem_aes_xts_storage.h"
#include "core/file_sys/fssystem/fssystem_pooled_buffer.h"
#include "core/file_sys/fssystem/fssystem_utility.h"
namespace FileSys {
void AesXtsStorage::MakeAesXtsIv(void* dst, size_t dst_size, s64 offset, size_t block_size) {
ASSERT(dst != nullptr);
ASSERT(dst_size == IvSize);
ASSERT(offset >= 0);
const uintptr_t out_addr = reinterpret_cast<uintptr_t>(dst);
*reinterpret_cast<s64_be*>(out_addr + sizeof(s64)) = offset / block_size;
}
AesXtsStorage::AesXtsStorage(VirtualFile base, const void* key1, const void* key2, size_t key_size,
const void* iv, size_t iv_size, size_t block_size)
: m_base_storage(std::move(base)), m_block_size(block_size), m_mutex() {
ASSERT(m_base_storage != nullptr);
ASSERT(key1 != nullptr);
ASSERT(key2 != nullptr);
ASSERT(iv != nullptr);
ASSERT(key_size == KeySize);
ASSERT(iv_size == IvSize);
ASSERT(Common::IsAligned(m_block_size, AesBlockSize));
std::memcpy(m_key.data() + 0, key1, KeySize / 2);
std::memcpy(m_key.data() + 0x10, key2, KeySize / 2);
std::memcpy(m_iv.data(), iv, IvSize);
m_cipher.emplace(m_key, Core::Crypto::Mode::XTS);
}
size_t AesXtsStorage::Read(u8* buffer, size_t size, size_t offset) const {
// Allow zero-size reads.
if (size == 0) {
return size;
}
// Ensure buffer is valid.
ASSERT(buffer != nullptr);
// We can only read at block aligned offsets.
ASSERT(Common::IsAligned(offset, AesBlockSize));
ASSERT(Common::IsAligned(size, AesBlockSize));
// Read the data.
m_base_storage->Read(buffer, size, offset);
// Setup the counter.
std::array<u8, IvSize> ctr;
std::memcpy(ctr.data(), m_iv.data(), IvSize);
AddCounter(ctr.data(), IvSize, offset / m_block_size);
// Handle any unaligned data before the start.
size_t processed_size = 0;
if ((offset % m_block_size) != 0) {
// Determine the size of the pre-data read.
const size_t skip_size =
static_cast<size_t>(offset - Common::AlignDown(offset, m_block_size));
const size_t data_size = std::min(size, m_block_size - skip_size);
// Decrypt into a pooled buffer.
{
PooledBuffer tmp_buf(m_block_size, m_block_size);
ASSERT(tmp_buf.GetSize() >= m_block_size);
std::memset(tmp_buf.GetBuffer(), 0, skip_size);
std::memcpy(tmp_buf.GetBuffer() + skip_size, buffer, data_size);
m_cipher->SetIV(ctr);
m_cipher->Transcode(tmp_buf.GetBuffer(), m_block_size, tmp_buf.GetBuffer(),
Core::Crypto::Op::Decrypt);
std::memcpy(buffer, tmp_buf.GetBuffer() + skip_size, data_size);
}
AddCounter(ctr.data(), IvSize, 1);
processed_size += data_size;
ASSERT(processed_size == std::min(size, m_block_size - skip_size));
}
// Decrypt aligned chunks.
char* cur = reinterpret_cast<char*>(buffer) + processed_size;
size_t remaining = size - processed_size;
while (remaining > 0) {
const size_t cur_size = std::min(m_block_size, remaining);
m_cipher->SetIV(ctr);
m_cipher->Transcode(cur, cur_size, cur, Core::Crypto::Op::Decrypt);
remaining -= cur_size;
cur += cur_size;
AddCounter(ctr.data(), IvSize, 1);
}
return size;
}
size_t AesXtsStorage::GetSize() const {
return m_base_storage->GetSize();
}
} // namespace FileSys
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