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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/fssystem/fssystem_aes_ctr_storage.h"
#include "core/file_sys/fssystem/fssystem_pooled_buffer.h"
#include "core/file_sys/fssystem/fssystem_utility.h"
namespace FileSys {
void AesCtrStorage::MakeIv(void* dst, size_t dst_size, u64 upper, s64 offset) {
ASSERT(dst != nullptr);
ASSERT(dst_size == IvSize);
ASSERT(offset >= 0);
const uintptr_t out_addr = reinterpret_cast<uintptr_t>(dst);
*reinterpret_cast<u64_be*>(out_addr + 0) = upper;
*reinterpret_cast<s64_be*>(out_addr + sizeof(u64)) = static_cast<s64>(offset / BlockSize);
}
AesCtrStorage::AesCtrStorage(VirtualFile base, const void* key, size_t key_size, const void* iv,
size_t iv_size)
: m_base_storage(std::move(base)) {
ASSERT(m_base_storage != nullptr);
ASSERT(key != nullptr);
ASSERT(iv != nullptr);
ASSERT(key_size == KeySize);
ASSERT(iv_size == IvSize);
std::memcpy(m_key.data(), key, KeySize);
std::memcpy(m_iv.data(), iv, IvSize);
m_cipher.emplace(m_key, Core::Crypto::Mode::CTR);
}
size_t AesCtrStorage::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, BlockSize));
ASSERT(Common::IsAligned(size, BlockSize));
// 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 / BlockSize);
// Decrypt.
m_cipher->SetIV(ctr);
m_cipher->Transcode(buffer, size, buffer, Core::Crypto::Op::Decrypt);
return size;
}
size_t AesCtrStorage::Write(const u8* buffer, size_t size, size_t offset) {
// Allow zero-size writes.
if (size == 0) {
return size;
}
// Ensure buffer is valid.
ASSERT(buffer != nullptr);
// We can only write at block aligned offsets.
ASSERT(Common::IsAligned(offset, BlockSize));
ASSERT(Common::IsAligned(size, BlockSize));
// Get a pooled buffer.
PooledBuffer pooled_buffer;
const bool use_work_buffer = true;
if (use_work_buffer) {
pooled_buffer.Allocate(size, BlockSize);
}
// Setup the counter.
std::array<u8, IvSize> ctr;
std::memcpy(ctr.data(), m_iv.data(), IvSize);
AddCounter(ctr.data(), IvSize, offset / BlockSize);
// Loop until all data is written.
size_t remaining = size;
s64 cur_offset = 0;
while (remaining > 0) {
// Determine data we're writing and where.
const size_t write_size =
use_work_buffer ? std::min(pooled_buffer.GetSize(), remaining) : remaining;
void* write_buf;
if (use_work_buffer) {
write_buf = pooled_buffer.GetBuffer();
} else {
write_buf = const_cast<u8*>(buffer);
}
// Encrypt the data.
m_cipher->SetIV(ctr);
m_cipher->Transcode(buffer, write_size, reinterpret_cast<u8*>(write_buf),
Core::Crypto::Op::Encrypt);
// Write the encrypted data.
m_base_storage->Write(reinterpret_cast<u8*>(write_buf), write_size, offset + cur_offset);
// Advance.
cur_offset += write_size;
remaining -= write_size;
if (remaining > 0) {
AddCounter(ctr.data(), IvSize, write_size / BlockSize);
}
}
return size;
}
size_t AesCtrStorage::GetSize() const {
return m_base_storage->GetSize();
}
} // namespace FileSys
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