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Bootloader: installer now patches GPT GUID's

This commit is contained in:
Bananymous 2023-11-13 18:53:38 +02:00
parent 8a5753b0fe
commit b4775fbe75
4 changed files with 109 additions and 24 deletions
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8
bootloader/install.sh
View File

@ -7,6 +7,10 @@ if [[ -z $BANAN_DISK_IMAGE_PATH ]]; then
exit 1
fi
ROOT_PARTITION_INDEX=2
ROOT_PARTITION_INFO=$(fdisk -x $BANAN_DISK_IMAGE_PATH | grep "^$BANAN_DISK_IMAGE_PATH" | head -$ROOT_PARTITION_INDEX | tail -1)
ROOT_PARTITION_GUID=$(echo $ROOT_PARTITION_INFO | cut -d' ' -f6)
CURRENT_DIR=$(dirname $(realpath $0))
INSTALLER_DIR=$CURRENT_DIR/installer
@ -31,5 +35,5 @@ x86_64-banan_os-as $CURRENT_DIR/arch/x86_64/boot.S -o $BUILD_DIR/bootloader.o
echo linking bootloader
x86_64-banan_os-ld -nostdlib -T $CURRENT_DIR/arch/x86_64/linker.ld $BUILD_DIR/bootloader.o -o $BUILD_DIR/bootloader
echo installing bootloader
$INSTALLER_BUILD_DIR/x86_64-banan_os-bootloader-installer $BUILD_DIR/bootloader $BANAN_DISK_IMAGE_PATH
echo installing bootloader to
$INSTALLER_BUILD_DIR/x86_64-banan_os-bootloader-installer $BUILD_DIR/bootloader $BANAN_DISK_IMAGE_PATH $ROOT_PARTITION_GUID

97
bootloader/installer/GPT.cpp
View File

@ -63,18 +63,18 @@ const GPTHeader& GPTFile::gpt_header() const
return *reinterpret_cast<GPTHeader*>(m_mmap + SECTOR_SIZE);
}
bool GPTFile::install_bootcode(std::span<const uint8_t> boot_code)
bool GPTFile::install_stage1(std::span<const uint8_t> stage1)
{
auto& mbr = this->mbr();
if (boot_code.size() > sizeof(mbr.boot_code))
if (stage1.size() > sizeof(mbr.boot_code))
{
std::cerr << m_path << ": can't fit " << boot_code.size() << " bytes of boot code in mbr (max is " << sizeof(mbr.boot_code) << ")" << std::endl;
std::cerr << m_path << ": can't fit " << stage1.size() << " bytes of boot code in mbr (max is " << sizeof(mbr.boot_code) << ")" << std::endl;
return false;
}
// copy boot code
memcpy(mbr.boot_code, boot_code.data(), boot_code.size());
memcpy(mbr.boot_code, stage1.data(), stage1.size());
// setup mbr
mbr.unique_mbr_disk_signature = 0xdeadbeef;
@ -99,29 +99,104 @@ bool GPTFile::install_bootcode(std::span<const uint8_t> boot_code)
return true;
}
bool GPTFile::write_partition(std::span<const uint8_t> data, GUID type_guid)
bool GPTFile::install_stage2(std::span<const uint8_t> stage2, const GUID& root_partition_guid)
{
auto partition = find_partition(type_guid);
if (stage2.size() < 16)
{
std::cerr << m_path << ": contains invalid .stage2 section, too small for patches" << std::endl;
return false;
}
// find GUID patch offsets
std::size_t disk_guid_offset(-1);
std::size_t part_guid_offset(-1);
for (std::size_t i = 0; i < stage2.size() - 16; i++)
{
if (memcmp(stage2.data() + i, "root disk guid ", 16) == 0)
{
if (disk_guid_offset != std::size_t(-1))
{
std::cerr << m_path << ": contains invalid .stage2 section, multiple patchable disk guids" << std::endl;
return false;
}
disk_guid_offset = i;
}
if (memcmp(stage2.data() + i, "root part guid ", 16) == 0)
{
if (part_guid_offset != std::size_t(-1))
{
std::cerr << m_path << ": contains invalid .stage2 section, multiple patchable partition guids" << std::endl;
return false;
}
part_guid_offset = i;
}
}
if (disk_guid_offset == std::size_t(-1))
{
std::cerr << m_path << ": contains invalid .stage2 section, no patchable disk guid" << std::endl;
return false;
}
if (part_guid_offset == std::size_t(-1))
{
std::cerr << m_path << ": contains invalid .stage2 section, no patchable partition guid" << std::endl;
return false;
}
auto partition = find_partition_with_type(bios_boot_guid);
if (!partition.has_value())
{
std::cerr << m_path << ": could not find partition with type " << type_guid << std::endl;
std::cerr << m_path << ": could not find partition with type " << bios_boot_guid << std::endl;
return false;
}
const std::size_t partition_size = (partition->ending_lba - partition->starting_lba + 1) * SECTOR_SIZE;
if (data.size() > partition_size)
if (stage2.size() > partition_size)
{
std::cerr << m_path << ": can't fit " << data.size() << " bytes of data to partition of size " << partition_size << std::endl;
std::cerr << m_path << ": can't fit " << stage2.size() << " bytes of data to partition of size " << partition_size << std::endl;
return false;
}
memcpy(m_mmap + partition->starting_lba * SECTOR_SIZE, data.data(), data.size());
uint8_t* partition_start = m_mmap + partition->starting_lba * SECTOR_SIZE;
memcpy(partition_start, stage2.data(), stage2.size());
// patch GUIDs
*reinterpret_cast<GUID*>(partition_start + disk_guid_offset) = gpt_header().disk_guid;
*reinterpret_cast<GUID*>(partition_start + part_guid_offset) = root_partition_guid;
return true;
}
std::optional<GPTPartitionEntry> GPTFile::find_partition(const GUID& type_guid) const
bool GPTFile::install_bootloader(std::span<const uint8_t> stage1, std::span<const uint8_t> stage2, const GUID& root_partition_guid)
{
if (!find_partition_with_guid(root_partition_guid).has_value())
{
std::cerr << m_path << ": no partition with GUID " << root_partition_guid << std::endl;
return false;
}
if (!install_stage1(stage1))
return false;
if (!install_stage2(stage2, root_partition_guid))
return false;
return true;
}
std::optional<GPTPartitionEntry> GPTFile::find_partition_with_guid(const GUID& guid) const
{
const auto& gpt_header = this->gpt_header();
const uint8_t* partition_entry_array_start = m_mmap + gpt_header.partition_entry_lba * SECTOR_SIZE;
for (std::size_t i = 0; i < gpt_header.number_of_partition_entries; i++)
{
const auto& partition_entry = *reinterpret_cast<const GPTPartitionEntry*>(partition_entry_array_start + i * gpt_header.size_of_partition_entry);
if (partition_entry.partition_guid != guid)
continue;
return partition_entry;
}
return {};
}
std::optional<GPTPartitionEntry> GPTFile::find_partition_with_type(const GUID& type_guid) const
{
const auto& gpt_header = this->gpt_header();
const uint8_t* partition_entry_array_start = m_mmap + gpt_header.partition_entry_lba * SECTOR_SIZE;

9
bootloader/installer/GPT.h
View File

@ -65,8 +65,7 @@ public:
GPTFile(std::string_view path);
~GPTFile();
bool install_bootcode(std::span<const uint8_t>);
bool write_partition(std::span<const uint8_t>, GUID type_guid);
bool install_bootloader(std::span<const uint8_t> stage1, std::span<const uint8_t> stage2, const GUID& root_partition_guid);
const GPTHeader& gpt_header() const;
@ -77,7 +76,11 @@ public:
private:
MBR& mbr();
bool validate_gpt_header() const;
std::optional<GPTPartitionEntry> find_partition(const GUID& type_guid) const;
std::optional<GPTPartitionEntry> find_partition_with_guid(const GUID& guid) const;
std::optional<GPTPartitionEntry> find_partition_with_type(const GUID& type_guid) const;
bool install_stage1(std::span<const uint8_t> stage1);
bool install_stage2(std::span<const uint8_t> stage2, const GUID& root_partition_guid);
private:
const std::string m_path;

19
bootloader/installer/main.cpp
View File

@ -7,9 +7,16 @@ int main(int argc, char** argv)
{
using namespace std::string_view_literals;
if (argc != 3)
if (argc != 4)
{
std::fprintf(stderr, "usage: %s BOOTLOADER DISK_IMAGE}\n", argv[0]);
std::fprintf(stderr, "usage: %s BOOTLOADER DISK_IMAGE ROOT_PARTITION_GUID\n", argv[0]);
return 1;
}
auto root_partition_guid = GUID::from_string(argv[3]);
if (!root_partition_guid.has_value())
{
std::cerr << "invalid guid '" << argv[3] << '\'' << std::endl;
return 1;
}
@ -29,13 +36,9 @@ int main(int argc, char** argv)
if (!disk_image.success())
return 1;
if (!disk_image.install_bootcode(*stage1))
if (!disk_image.install_bootloader(*stage1, *stage2, *root_partition_guid))
return 1;
std::cout << "wrote stage1 bootloader" << std::endl;
if (!disk_image.write_partition(*stage2, bios_boot_guid))
return 1;
std::cout << "wrote stage2 bootloader" << std::endl;
std::cout << "bootloader installed" << std::endl;
return 0;
}