dolphin/Source/Core/DiscIO/NANDImporter.cpp

// Copyright 2017 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

#include "DiscIO/NANDImporter.h"

#include <algorithm>
#include <array>
#include <cstring>

#include <fmt/format.h>

#include "Common/Crypto/AES.h"
#include "Common/FileUtil.h"
#include "Common/IOFile.h"
#include "Common/Logging/Log.h"
#include "Common/MsgHandler.h"
#include "Common/Swap.h"
#include "Core/IOS/ES/Formats.h"

namespace DiscIO
{
constexpr size_t NAND_SIZE = 0x20000000;
constexpr size_t NAND_KEYS_SIZE = 0x400;

NANDImporter::NANDImporter() = default;
NANDImporter::~NANDImporter() = default;

void NANDImporter::ImportNANDBin(const std::string& path_to_bin,
                                 std::function<void()> update_callback,
                                 std::function<std::string()> get_otp_dump_path)
{
  m_update_callback = std::move(update_callback);

  if (!ReadNANDBin(path_to_bin, get_otp_dump_path))
    return;

  const std::string nand_root = File::GetUserPath(D_WIIROOT_IDX);
  m_nand_root_length = nand_root.length();
  if (nand_root.back() == '/')
    m_nand_root_length++;

  FindSuperblock();
  ProcessEntry(0, nand_root);
  ExportKeys(nand_root);
  ExtractCertificates(nand_root);
}

bool NANDImporter::ReadNANDBin(const std::string& path_to_bin,
                               std::function<std::string()> get_otp_dump_path)
{
  constexpr size_t NAND_TOTAL_BLOCKS = 0x40000;
  constexpr size_t NAND_BLOCK_SIZE = 0x800;
  constexpr size_t NAND_ECC_BLOCK_SIZE = 0x40;
  constexpr size_t NAND_BIN_SIZE =
      (NAND_BLOCK_SIZE + NAND_ECC_BLOCK_SIZE) * NAND_TOTAL_BLOCKS;  // 0x21000000

  File::IOFile file(path_to_bin, "rb");
  const u64 image_size = file.GetSize();
  if (image_size != NAND_BIN_SIZE + NAND_KEYS_SIZE && image_size != NAND_BIN_SIZE)
  {
    PanicAlertFmtT("This file does not look like a BootMii NAND backup.");
    return false;
  }

  m_nand.resize(NAND_SIZE);

  for (size_t i = 0; i < NAND_TOTAL_BLOCKS; i++)
  {
    // Instead of updating on every cycle, we only update every 1000 cycles for a balance between
    // not updating fast enough vs updating too fast
    if (i % 1000 == 0)
      m_update_callback();

    file.ReadBytes(&m_nand[i * NAND_BLOCK_SIZE], NAND_BLOCK_SIZE);
    file.Seek(NAND_ECC_BLOCK_SIZE, SEEK_CUR);  // We don't care about the ECC blocks
  }

  m_nand_keys.resize(NAND_KEYS_SIZE);

  // Read the OTP/SEEPROM dump.
  // If it is not included in the NAND image, get a path to the dump and read key data from it.
  if (image_size == NAND_BIN_SIZE)
  {
    const std::string otp_dump_path = get_otp_dump_path();
    if (otp_dump_path.empty())
      return false;
    File::IOFile keys_file{otp_dump_path, "rb"};
    return keys_file.ReadBytes(m_nand_keys.data(), NAND_KEYS_SIZE);
  }

  // Otherwise, just read the key data from the NAND image.
  return file.ReadBytes(m_nand_keys.data(), NAND_KEYS_SIZE);
}

void NANDImporter::FindSuperblock()
{
  constexpr size_t NAND_SUPERBLOCK_START = 0x1fc00000;
  constexpr size_t NAND_SUPERBLOCK_SIZE = 0x40000;

  size_t superblock = 0;
  u32 newest_version = 0;
  for (size_t pos = NAND_SUPERBLOCK_START; pos < NAND_SIZE; pos += NAND_SUPERBLOCK_SIZE)
  {
    if (!memcmp(m_nand.data() + pos, "SFFS", 4))
    {
      const u32 version = Common::swap32(&m_nand[pos + 4]);
      INFO_LOG_FMT(DISCIO, "Found superblock at {:#x} with version {:#x}", pos, version);
      if (superblock == 0 || version > newest_version)
      {
        superblock = pos;
        newest_version = version;
      }
    }
  }

  m_nand_fat_offset = superblock + 0xC;
  m_nand_fst_offset = m_nand_fat_offset + 0x10000;
  INFO_LOG_FMT(DISCIO,
               "Using superblock version {:#x} at position {:#x}. FAT/FST offset: {:#x}/{:#x}",
               newest_version, superblock, m_nand_fat_offset, m_nand_fst_offset);
}

std::string NANDImporter::GetPath(const NANDFSTEntry& entry, const std::string& parent_path)
{
  std::string name(entry.name, strnlen(entry.name, sizeof(NANDFSTEntry::name)));

  if (name.front() == '/' || parent_path.back() == '/')
    return parent_path + name;

  return parent_path + '/' + name;
}

std::string NANDImporter::FormatDebugString(const NANDFSTEntry& entry)
{
  return fmt::format(
      "{:12.12} {:#04x} {:#04x} {:#06x} {:#06x} {:#010x} {:#06x} {:#06x} {:#06x} {:#010x}",
      entry.name, entry.mode, entry.attr, entry.sub, entry.sib, entry.size, entry.x1, entry.uid,
      entry.gid, entry.x3);
}

void NANDImporter::ProcessEntry(u16 entry_number, const std::string& parent_path)
{
  NANDFSTEntry entry;
  memcpy(&entry, &m_nand[m_nand_fst_offset + sizeof(NANDFSTEntry) * Common::swap16(entry_number)],
         sizeof(NANDFSTEntry));

  if (entry.sib != 0xffff)
    ProcessEntry(entry.sib, parent_path);

  if ((entry.mode & 3) == 1)
    ProcessFile(entry, parent_path);
  else if ((entry.mode & 3) == 2)
    ProcessDirectory(entry, parent_path);
  else
    ERROR_LOG_FMT(DISCIO, "Unknown mode: {}", FormatDebugString(entry));
}

void NANDImporter::ProcessDirectory(const NANDFSTEntry& entry, const std::string& parent_path)
{
  m_update_callback();
  INFO_LOG_FMT(DISCIO, "Path: {}", FormatDebugString(entry));

  const std::string path = GetPath(entry, parent_path);
  File::CreateDir(path);

  if (entry.sub != 0xffff)
    ProcessEntry(entry.sub, path);

  INFO_LOG_FMT(DISCIO, "Path: {}", parent_path.data() + m_nand_root_length);
}

void NANDImporter::ProcessFile(const NANDFSTEntry& entry, const std::string& parent_path)
{
  constexpr size_t NAND_AES_KEY_OFFSET = 0x158;
  constexpr size_t NAND_FAT_BLOCK_SIZE = 0x4000;

  m_update_callback();
  INFO_LOG_FMT(DISCIO, "File: {}", FormatDebugString(entry));

  const std::string path = GetPath(entry, parent_path);
  File::IOFile file(path, "wb");
  std::array<u8, 16> key{};
  std::copy(&m_nand_keys[NAND_AES_KEY_OFFSET], &m_nand_keys[NAND_AES_KEY_OFFSET + key.size()],
            key.begin());
  u16 sub = Common::swap16(entry.sub);
  u32 remaining_bytes = Common::swap32(entry.size);

  while (remaining_bytes > 0)
  {
    std::array<u8, 16> iv{};
    std::vector<u8> block = Common::AES::Decrypt(
        key.data(), iv.data(), &m_nand[NAND_FAT_BLOCK_SIZE * sub], NAND_FAT_BLOCK_SIZE);
    u32 size = remaining_bytes < NAND_FAT_BLOCK_SIZE ? remaining_bytes : NAND_FAT_BLOCK_SIZE;
    file.WriteBytes(block.data(), size);
    remaining_bytes -= size;
    sub = Common::swap16(&m_nand[m_nand_fat_offset + 2 * sub]);
  }
}

bool NANDImporter::ExtractCertificates(const std::string& nand_root)
{
  const std::string content_dir = nand_root + "/title/00000001/0000000d/content/";

  File::IOFile tmd_file(content_dir + "title.tmd", "rb");
  std::vector<u8> tmd_bytes(tmd_file.GetSize());
  if (!tmd_file.ReadBytes(tmd_bytes.data(), tmd_bytes.size()))
  {
    ERROR_LOG_FMT(DISCIO, "ExtractCertificates: Could not read IOS13 TMD");
    return false;
  }

  IOS::ES::TMDReader tmd(std::move(tmd_bytes));
  IOS::ES::Content content_metadata;
  if (!tmd.GetContent(tmd.GetBootIndex(), &content_metadata))
  {
    ERROR_LOG_FMT(DISCIO, "ExtractCertificates: Could not get content ID from TMD");
    return false;
  }

  File::IOFile content_file(content_dir + fmt::format("{:08x}.app", content_metadata.id), "rb");
  std::vector<u8> content_bytes(content_file.GetSize());
  if (!content_file.ReadBytes(content_bytes.data(), content_bytes.size()))
  {
    ERROR_LOG_FMT(DISCIO, "ExtractCertificates: Could not read IOS13 contents");
    return false;
  }

  struct PEMCertificate
  {
    std::string_view filename;
    std::array<u8, 4> search_bytes;
  };

  static constexpr std::array<PEMCertificate, 3> certificates{{
      {"/clientca.pem", {{0x30, 0x82, 0x03, 0xE9}}},
      {"/clientcakey.pem", {{0x30, 0x82, 0x02, 0x5D}}},
      {"/rootca.pem", {{0x30, 0x82, 0x03, 0x7D}}},
  }};

  for (const PEMCertificate& certificate : certificates)
  {
    const auto search_result =
        std::search(content_bytes.begin(), content_bytes.end(), certificate.search_bytes.begin(),
                    certificate.search_bytes.end());

    if (search_result == content_bytes.end())
    {
      ERROR_LOG_FMT(DISCIO, "ExtractCertificates: Could not find offset for certficate '{}'",
                    certificate.filename);
      return false;
    }

    const std::string pem_file_path = nand_root + std::string(certificate.filename);
    const ptrdiff_t certificate_offset = std::distance(content_bytes.begin(), search_result);
    const u16 certificate_size = Common::swap16(&content_bytes[certificate_offset - 2]);
    INFO_LOG_FMT(DISCIO, "ExtractCertificates: '{}' offset: {:#x} size: {:#x}",
                 certificate.filename, certificate_offset, certificate_size);

    File::IOFile pem_file(pem_file_path, "wb");
    if (!pem_file.WriteBytes(&content_bytes[certificate_offset], certificate_size))
    {
      ERROR_LOG_FMT(DISCIO, "ExtractCertificates: Unable to write to file {}", pem_file_path);
      return false;
    }
  }
  return true;
}

void NANDImporter::ExportKeys(const std::string& nand_root)
{
  const std::string file_path = nand_root + "/keys.bin";
  File::IOFile file(file_path, "wb");
  if (!file.WriteBytes(m_nand_keys.data(), NAND_KEYS_SIZE))
    PanicAlertFmtT("Unable to write to file {0}", file_path);
}
}  // namespace DiscIO