| /* |
| * Block driver for Hyper-V VHDX Images |
| * |
| * Copyright (c) 2013 Red Hat, Inc., |
| * |
| * Authors: |
| * Jeff Cody <jcody@redhat.com> |
| * |
| * This is based on the "VHDX Format Specification v0.95", published 4/12/2012 |
| * by Microsoft: |
| * https://www.microsoft.com/en-us/download/details.aspx?id=29681 |
| * |
| * This work is licensed under the terms of the GNU LGPL, version 2 or later. |
| * See the COPYING.LIB file in the top-level directory. |
| * |
| */ |
| |
| #ifndef BLOCK_VHDX_H |
| #define BLOCK_VHDX_H |
| |
| /* Structures and fields present in the VHDX file */ |
| |
| /* The header section has the following blocks, |
| * each block is 64KB: |
| * |
| * _____________________________________________________________________________ |
| * | File Id. | Header 1 | Header 2 | Region Table | Reserved (768KB) | |
| * |----------|---------------|------------|--------------|--------------------| |
| * | | | | | | |
| * 0.........64KB...........128KB........192KB..........256KB................1MB |
| */ |
| |
| #define VHDX_HEADER_BLOCK_SIZE (64*1024) |
| |
| #define VHDX_FILE_ID_OFFSET 0 |
| #define VHDX_HEADER1_OFFSET (VHDX_HEADER_BLOCK_SIZE*1) |
| #define VHDX_HEADER2_OFFSET (VHDX_HEADER_BLOCK_SIZE*2) |
| #define VHDX_REGION_TABLE_OFFSET (VHDX_HEADER_BLOCK_SIZE*3) |
| |
| |
| /* |
| * A note on the use of MS-GUID fields. For more details on the GUID, |
| * please see: https://en.wikipedia.org/wiki/Globally_unique_identifier. |
| * |
| * The VHDX specification only states that these are MS GUIDs, and which |
| * bytes are data1-data4. It makes no mention of what algorithm should be used |
| * to generate the GUID, nor what standard. However, looking at the specified |
| * known GUID fields, it appears the GUIDs are: |
| * Standard/DCE GUID type (noted by 10b in the MSB of byte 0 of .data4) |
| * Random algorithm (noted by 0x4XXX for .data3) |
| */ |
| |
| /* ---- HEADER SECTION STRUCTURES ---- */ |
| |
| /* These structures are ones that are defined in the VHDX specification |
| * document */ |
| |
| typedef struct VHDXFileIdentifier { |
| uint64_t signature; /* "vhdxfile" in ASCII */ |
| uint16_t creator[256]; /* optional; utf-16 string to identify |
| the vhdx file creator. Diagnotistic |
| only */ |
| } VHDXFileIdentifier; |
| |
| |
| /* the guid is a 16 byte unique ID - the definition for this used by |
| * Microsoft is not just 16 bytes though - it is a structure that is defined, |
| * so we need to follow it here so that endianness does not trip us up */ |
| |
| typedef struct MSGUID { |
| uint32_t data1; |
| uint16_t data2; |
| uint16_t data3; |
| uint8_t data4[8]; |
| } MSGUID; |
| |
| #define guid_eq(a, b) \ |
| (memcmp(&(a), &(b), sizeof(MSGUID)) == 0) |
| |
| #define VHDX_HEADER_SIZE (4*1024) /* although the vhdx_header struct in disk |
| is only 582 bytes, for purposes of crc |
| the header is the first 4KB of the 64KB |
| block */ |
| |
| /* The full header is 4KB, although the actual header data is much smaller. |
| * But for the checksum calculation, it is over the entire 4KB structure, |
| * not just the defined portion of it */ |
| typedef struct QEMU_PACKED VHDXHeader { |
| uint32_t signature; /* "head" in ASCII */ |
| uint32_t checksum; /* CRC-32C hash of the whole header */ |
| uint64_t sequence_number; /* Seq number of this header. Each |
| VHDX file has 2 of these headers, |
| and only the header with the highest |
| sequence number is valid */ |
| MSGUID file_write_guid; /* 128 bit unique identifier. Must be |
| updated to new, unique value before |
| the first modification is made to |
| file */ |
| MSGUID data_write_guid; /* 128 bit unique identifier. Must be |
| updated to new, unique value before |
| the first modification is made to |
| visible data. Visbile data is |
| defined as: |
| - system & user metadata |
| - raw block data |
| - disk size |
| - any change that will |
| cause the virtual disk |
| sector read to differ |
| |
| This does not need to change if |
| blocks are re-arranged */ |
| MSGUID log_guid; /* 128 bit unique identifier. If zero, |
| there is no valid log. If non-zero, |
| log entries with this guid are |
| valid. */ |
| uint16_t log_version; /* version of the log format. Mustn't be |
| zero, unless log_guid is also zero */ |
| uint16_t version; /* version of th evhdx file. Currently, |
| only supported version is "1" */ |
| uint32_t log_length; /* length of the log. Must be multiple |
| of 1MB */ |
| uint64_t log_offset; /* byte offset in the file of the log. |
| Must also be a multiple of 1MB */ |
| } VHDXHeader; |
| |
| /* Header for the region table block */ |
| typedef struct QEMU_PACKED VHDXRegionTableHeader { |
| uint32_t signature; /* "regi" in ASCII */ |
| uint32_t checksum; /* CRC-32C hash of the 64KB table */ |
| uint32_t entry_count; /* number of valid entries */ |
| uint32_t reserved; |
| } VHDXRegionTableHeader; |
| |
| /* Individual region table entry. There may be a maximum of 2047 of these |
| * |
| * There are two known region table properties. Both are required. |
| * BAT (block allocation table): 2DC27766F62342009D64115E9BFD4A08 |
| * Metadata: 8B7CA20647904B9AB8FE575F050F886E |
| */ |
| #define VHDX_REGION_ENTRY_REQUIRED 0x01 /* if set, parser must understand |
| this entry in order to open |
| file */ |
| typedef struct QEMU_PACKED VHDXRegionTableEntry { |
| MSGUID guid; /* 128-bit unique identifier */ |
| uint64_t file_offset; /* offset of the object in the file. |
| Must be multiple of 1MB */ |
| uint32_t length; /* length, in bytes, of the object */ |
| uint32_t data_bits; |
| } VHDXRegionTableEntry; |
| |
| |
| /* ---- LOG ENTRY STRUCTURES ---- */ |
| #define VHDX_LOG_HDR_SIZE 64 |
| typedef struct QEMU_PACKED VHDXLogEntryHeader { |
| uint32_t signature; /* "loge" in ASCII */ |
| uint32_t checksum; /* CRC-32C hash of the 64KB table */ |
| uint32_t entry_length; /* length in bytes, multiple of 1MB */ |
| uint32_t tail; /* byte offset of first log entry of a |
| seq, where this entry is the last |
| entry */ |
| uint64_t sequence_number; /* incremented with each log entry. |
| May not be zero. */ |
| uint32_t descriptor_count; /* number of descriptors in this log |
| entry, must be >= 0 */ |
| uint32_t reserved; |
| MSGUID log_guid; /* value of the log_guid from |
| vhdx_header. If not found in |
| vhdx_header, it is invalid */ |
| uint64_t flushed_file_offset; /* see spec for full details - this |
| sould be vhdx file size in bytes */ |
| uint64_t last_file_offset; /* size in bytes that all allocated |
| file structures fit into */ |
| } VHDXLogEntryHeader; |
| |
| #define VHDX_LOG_DESC_SIZE 32 |
| |
| typedef struct QEMU_PACKED VHDXLogDescriptor { |
| uint32_t signature; /* "zero" or "desc" in ASCII */ |
| union { |
| uint32_t reserved; /* zero desc */ |
| uint32_t trailing_bytes; /* data desc: bytes 4092-4096 of the |
| data sector */ |
| }; |
| union { |
| uint64_t zero_length; /* zero desc: length of the section to |
| zero */ |
| uint64_t leading_bytes; /* data desc: bytes 0-7 of the data |
| sector */ |
| }; |
| uint64_t file_offset; /* file offset to write zeros - multiple |
| of 4kB */ |
| uint64_t sequence_number; /* must match same field in |
| vhdx_log_entry_header */ |
| } VHDXLogDescriptor; |
| |
| typedef struct QEMU_PACKED VHDXLogDataSector { |
| uint32_t data_signature; /* "data" in ASCII */ |
| uint32_t sequence_high; /* 4 MSB of 8 byte sequence_number */ |
| uint8_t data[4084]; /* raw data, bytes 8-4091 (inclusive). |
| see the data descriptor field for the |
| other mising bytes */ |
| uint32_t sequence_low; /* 4 LSB of 8 byte sequence_number */ |
| } VHDXLogDataSector; |
| |
| |
| |
| /* block states - different state values depending on whether it is a |
| * payload block, or a sector block. */ |
| |
| #define PAYLOAD_BLOCK_NOT_PRESENT 0 |
| #define PAYLOAD_BLOCK_UNDEFINED 1 |
| #define PAYLOAD_BLOCK_ZERO 2 |
| #define PAYLOAD_BLOCK_UNMAPPED 5 |
| #define PAYLOAD_BLOCK_FULL_PRESENT 6 |
| #define PAYLOAD_BLOCK_PARTIALLY_PRESENT 7 |
| |
| #define SB_BLOCK_NOT_PRESENT 0 |
| #define SB_BLOCK_PRESENT 6 |
| |
| /* per the spec */ |
| #define VHDX_MAX_SECTORS_PER_BLOCK (1<<23) |
| |
| /* upper 44 bits are the file offset in 1MB units lower 3 bits are the state |
| other bits are reserved */ |
| #define VHDX_BAT_STATE_BIT_MASK 0x07 |
| #define VHDX_BAT_FILE_OFF_BITS (64-44) |
| typedef uint64_t VHDXBatEntry; |
| |
| /* ---- METADATA REGION STRUCTURES ---- */ |
| |
| #define VHDX_METADATA_ENTRY_SIZE 32 |
| #define VHDX_METADATA_MAX_ENTRIES 2047 /* not including the header */ |
| #define VHDX_METADATA_TABLE_MAX_SIZE \ |
| (VHDX_METADATA_ENTRY_SIZE * (VHDX_METADATA_MAX_ENTRIES+1)) |
| typedef struct QEMU_PACKED VHDXMetadataTableHeader { |
| uint64_t signature; /* "metadata" in ASCII */ |
| uint16_t reserved; |
| uint16_t entry_count; /* number table entries. <= 2047 */ |
| uint32_t reserved2[5]; |
| } VHDXMetadataTableHeader; |
| |
| #define VHDX_META_FLAGS_IS_USER 0x01 /* max 1024 entries */ |
| #define VHDX_META_FLAGS_IS_VIRTUAL_DISK 0x02 /* virtual disk metadata if set, |
| otherwise file metdata */ |
| #define VHDX_META_FLAGS_IS_REQUIRED 0x04 /* parse must understand this |
| entry to open the file */ |
| typedef struct QEMU_PACKED VHDXMetadataTableEntry { |
| MSGUID item_id; /* 128-bit identifier for metadata */ |
| uint32_t offset; /* byte offset of the metadata. At |
| least 64kB. Relative to start of |
| metadata region */ |
| /* note: if length = 0, so is offset */ |
| uint32_t length; /* length of metadata. <= 1MB. */ |
| uint32_t data_bits; /* least-significant 3 bits are flags, the |
| rest are reserved (see above) */ |
| uint32_t reserved2; |
| } VHDXMetadataTableEntry; |
| |
| #define VHDX_PARAMS_LEAVE_BLOCKS_ALLOCED 0x01 /* Do not change any blocks to |
| be BLOCK_NOT_PRESENT. |
| If set indicates a fixed |
| size VHDX file */ |
| #define VHDX_PARAMS_HAS_PARENT 0x02 /* has parent / backing file */ |
| typedef struct QEMU_PACKED VHDXFileParameters { |
| uint32_t block_size; /* size of each payload block, always |
| power of 2, <= 256MB and >= 1MB. */ |
| uint32_t data_bits; /* least-significant 2 bits are flags, the rest |
| are reserved (see above) */ |
| } VHDXFileParameters; |
| |
| typedef struct QEMU_PACKED VHDXVirtualDiskSize { |
| uint64_t virtual_disk_size; /* Size of the virtual disk, in bytes. |
| Must be multiple of the sector size, |
| max of 64TB */ |
| } VHDXVirtualDiskSize; |
| |
| typedef struct QEMU_PACKED VHDXPage83Data { |
| MSGUID page_83_data[16]; /* unique id for scsi devices that |
| support page 0x83 */ |
| } VHDXPage83Data; |
| |
| typedef struct QEMU_PACKED VHDXVirtualDiskLogicalSectorSize { |
| uint32_t logical_sector_size; /* virtual disk sector size (in bytes). |
| Can only be 512 or 4096 bytes */ |
| } VHDXVirtualDiskLogicalSectorSize; |
| |
| typedef struct QEMU_PACKED VHDXVirtualDiskPhysicalSectorSize { |
| uint32_t physical_sector_size; /* physical sector size (in bytes). |
| Can only be 512 or 4096 bytes */ |
| } VHDXVirtualDiskPhysicalSectorSize; |
| |
| typedef struct QEMU_PACKED VHDXParentLocatorHeader { |
| MSGUID locator_type[16]; /* type of the parent virtual disk. */ |
| uint16_t reserved; |
| uint16_t key_value_count; /* number of key/value pairs for this |
| locator */ |
| } VHDXParentLocatorHeader; |
| |
| /* key and value strings are UNICODE strings, UTF-16 LE encoding, no NULs */ |
| typedef struct QEMU_PACKED VHDXParentLocatorEntry { |
| uint32_t key_offset; /* offset in metadata for key, > 0 */ |
| uint32_t value_offset; /* offset in metadata for value, >0 */ |
| uint16_t key_length; /* length of entry key, > 0 */ |
| uint16_t value_length; /* length of entry value, > 0 */ |
| } VHDXParentLocatorEntry; |
| |
| |
| /* ----- END VHDX SPECIFICATION STRUCTURES ---- */ |
| |
| |
| uint32_t vhdx_checksum_calc(uint32_t crc, uint8_t *buf, size_t size, |
| int crc_offset); |
| |
| bool vhdx_checksum_is_valid(uint8_t *buf, size_t size, int crc_offset); |
| |
| |
| static void leguid_to_cpus(MSGUID *guid) |
| { |
| le32_to_cpus(&guid->data1); |
| le16_to_cpus(&guid->data2); |
| le16_to_cpus(&guid->data3); |
| } |
| |
| #endif |
