proxmox-backup/src/backup/data_chunk.rs

342 lines
11 KiB
Rust

use failure::*;
use std::convert::TryInto;
use proxmox::tools::io::{ReadExt, WriteExt};
use super::*;
/// Data chunk with positional information
pub struct ChunkInfo {
pub chunk: DataChunk,
pub chunk_len: u64,
pub offset: u64,
}
/// Data chunk binary storage format
///
/// Data chunks are identified by a unique digest, and can be
/// compressed and encrypted. A simply binary format is used to store
/// them on disk or transfer them over the network.
///
/// Please use the ``DataChunkBuilder`` to create new instances.
pub struct DataChunk {
digest: [u8; 32],
raw_data: Vec<u8>, // tagged, compressed, encryped data
}
impl DataChunk {
/// accessor to raw_data field
pub fn raw_data(&self) -> &[u8] {
&self.raw_data
}
/// accessor to chunk digest field
pub fn digest(&self) -> &[u8; 32] {
&self.digest
}
/// accessor to chunk type (magic number)
pub fn magic(&self) -> &[u8; 8] {
self.raw_data[0..8].try_into().unwrap()
}
/// accessor to crc32 checksum
pub fn crc(&self) -> u32 {
let crc_o = proxmox::tools::offsetof!(DataChunkHeader, crc);
u32::from_le_bytes(self.raw_data[crc_o..crc_o+4].try_into().unwrap())
}
// set the CRC checksum field
pub fn set_crc(&mut self, crc: u32) {
let crc_o = proxmox::tools::offsetof!(DataChunkHeader, crc);
self.raw_data[crc_o..crc_o+4].copy_from_slice(&crc.to_le_bytes());
}
/// compute the CRC32 checksum
pub fn compute_crc(&self) -> u32 {
let mut hasher = crc32fast::Hasher::new();
let start = std::mem::size_of::<DataChunkHeader>(); // start after HEAD
hasher.update(&self.raw_data[start..]);
hasher.finalize()
}
/// verify the CRC32 checksum
pub fn verify_crc(&self) -> Result<(), Error> {
let expected_crc = self.compute_crc();
if expected_crc != self.crc() {
bail!("Data chunk has wrong CRC checksum.");
}
Ok(())
}
fn encode(
data: &[u8],
config: Option<&CryptConfig>,
digest: [u8;32],
compress: bool,
) -> Result<Self, Error> {
if let Some(config) = config {
let compr_data;
let (_compress, data, magic) = if compress {
compr_data = zstd::block::compress(data, 1)?;
// Note: We only use compression if result is shorter
if compr_data.len() < data.len() {
(true, &compr_data[..], ENCR_COMPR_CHUNK_MAGIC_1_0)
} else {
(false, data, ENCRYPTED_CHUNK_MAGIC_1_0)
}
} else {
(false, data, ENCRYPTED_CHUNK_MAGIC_1_0)
};
let header_len = std::mem::size_of::<EncryptedDataChunkHeader>();
let mut raw_data = Vec::with_capacity(data.len() + header_len);
let dummy_head = EncryptedDataChunkHeader {
head: DataChunkHeader { magic: [0u8; 8], crc: [0; 4] },
iv: [0u8; 16],
tag: [0u8; 16],
};
unsafe {
raw_data.write_le_value(dummy_head)?;
}
let (iv, tag) = config.encrypt_to(data, &mut raw_data)?;
let head = EncryptedDataChunkHeader {
head: DataChunkHeader { magic, crc: [0; 4] }, iv, tag,
};
unsafe {
(&mut raw_data[0..header_len]).write_le_value(head)?;
}
return Ok(DataChunk { digest, raw_data });
} else {
let max_data_len = data.len() + std::mem::size_of::<DataChunkHeader>();
if compress {
let mut comp_data = Vec::with_capacity(max_data_len);
let head = DataChunkHeader {
magic: COMPRESSED_CHUNK_MAGIC_1_0,
crc: [0; 4],
};
unsafe {
comp_data.write_le_value(head)?;
}
zstd::stream::copy_encode(data, &mut comp_data, 1)?;
if comp_data.len() < max_data_len {
let chunk = DataChunk { digest, raw_data: comp_data };
return Ok(chunk);
}
}
let mut raw_data = Vec::with_capacity(max_data_len);
let head = DataChunkHeader {
magic: UNCOMPRESSED_CHUNK_MAGIC_1_0,
crc: [0; 4],
};
unsafe {
raw_data.write_le_value(head)?;
}
raw_data.extend_from_slice(data);
let chunk = DataChunk { digest, raw_data };
return Ok(chunk);
}
}
/// Decode chunk data
pub fn decode(self, config: Option<&CryptConfig>) -> Result<Vec<u8>, Error> {
let magic = self.magic();
if magic == &UNCOMPRESSED_CHUNK_MAGIC_1_0 {
let data_start = std::mem::size_of::<DataChunkHeader>();
return Ok(self.raw_data[data_start..].to_vec());
} else if magic == &COMPRESSED_CHUNK_MAGIC_1_0 {
let data_start = std::mem::size_of::<DataChunkHeader>();
let data = zstd::block::decompress(&self.raw_data[data_start..], 16*1024*1024)?;
return Ok(data);
} else if magic == &ENCR_COMPR_CHUNK_MAGIC_1_0 || magic == &ENCRYPTED_CHUNK_MAGIC_1_0 {
let header_len = std::mem::size_of::<EncryptedDataChunkHeader>();
let head = unsafe {
(&self.raw_data[..header_len]).read_le_value::<EncryptedDataChunkHeader>()?
};
if let Some(config) = config {
let data = if magic == &ENCR_COMPR_CHUNK_MAGIC_1_0 {
config.decode_compressed_chunk(&self.raw_data[header_len..], &head.iv, &head.tag)?
} else {
config.decode_uncompressed_chunk(&self.raw_data[header_len..], &head.iv, &head.tag)?
};
return Ok(data);
} else {
bail!("unable to decrypt chunk - missing CryptConfig");
}
} else {
bail!("Invalid chunk magic number.");
}
}
/// Load chunk data from ``reader``
///
/// Please note that it is impossible to compute the digest for
/// encrypted chunks, so we need to trust and use the provided
/// ``digest``.
pub fn load(reader: &mut dyn std::io::Read, digest: [u8; 32]) -> Result<Self, Error> {
let mut data = Vec::with_capacity(1024*1024);
reader.read_to_end(&mut data)?;
Self::from_raw(data, digest)
}
/// Create Instance from raw data
pub fn from_raw(data: Vec<u8>, digest: [u8;32]) -> Result<Self, Error> {
if data.len() < std::mem::size_of::<DataChunkHeader>() {
bail!("chunk too small ({} bytes).", data.len());
}
let magic = &data[0..8];
if magic == ENCR_COMPR_CHUNK_MAGIC_1_0 || magic == ENCRYPTED_CHUNK_MAGIC_1_0 {
if data.len() < std::mem::size_of::<EncryptedDataChunkHeader>() {
bail!("encrypted chunk too small ({} bytes).", data.len());
}
let chunk = DataChunk { digest: digest, raw_data: data };
Ok(chunk)
} else if magic == COMPRESSED_CHUNK_MAGIC_1_0 || magic == UNCOMPRESSED_CHUNK_MAGIC_1_0 {
let chunk = DataChunk { digest: digest, raw_data: data };
Ok(chunk)
} else {
bail!("unable to parse raw chunk - wrong magic");
}
}
/// Verify digest and data length for unencrypted chunks.
///
/// To do that, we need to decompress data first. Please note that
/// this is noth possible for encrypted chunks.
pub fn verify_unencrypted(&self, expected_chunk_size: usize) -> Result<(), Error> {
let magic = self.magic();
let verify_raw_data = |data: &[u8]| {
if expected_chunk_size != data.len() {
bail!("detected chunk with wrong length ({} != {})", expected_chunk_size, data.len());
}
let digest = openssl::sha::sha256(data);
if digest != self.digest {
bail!("detected chunk with wrong digest.");
}
Ok(())
};
if magic == &COMPRESSED_CHUNK_MAGIC_1_0 {
let data = zstd::block::decompress(&self.raw_data[12..], 16*1024*1024)?;
verify_raw_data(&data)?;
} else if magic == &UNCOMPRESSED_CHUNK_MAGIC_1_0 {
verify_raw_data(&self.raw_data[12..])?;
}
Ok(())
}
}
/// Builder for DataChunk
///
/// Main purpose is to centralize digest computation. Digest
/// computation differ for encryped chunk, and this interface ensures that
/// we always compute the correct one.
pub struct DataChunkBuilder<'a, 'b> {
config: Option<&'b CryptConfig>,
orig_data: &'a [u8],
digest_computed: bool,
digest: [u8; 32],
compress: bool,
}
impl <'a, 'b> DataChunkBuilder<'a, 'b> {
/// Create a new builder instance.
pub fn new(orig_data: &'a [u8]) -> Self {
Self {
orig_data,
config: None,
digest_computed: false,
digest: [0u8; 32],
compress: true,
}
}
/// Set compression flag.
///
/// If true, chunk data is compressed using zstd (level 1).
pub fn compress(mut self, value: bool) -> Self {
self.compress = value;
self
}
/// Set encryption Configuration
///
/// If set, chunks are encrypted.
pub fn crypt_config(mut self, value: &'b CryptConfig) -> Self {
if self.digest_computed {
panic!("unable to set crypt_config after compute_digest().");
}
self.config = Some(value);
self
}
fn compute_digest(&mut self) {
if !self.digest_computed {
if let Some(config) = self.config {
self.digest = config.compute_digest(self.orig_data);
} else {
self.digest = openssl::sha::sha256(self.orig_data);
}
self.digest_computed = true;
}
}
/// Returns the chunk Digest
///
/// Note: For encrypted chunks, this needs to be called after
/// ``crypt_config``.
pub fn digest(&mut self) -> &[u8; 32] {
if !self.digest_computed {
self.compute_digest();
}
&self.digest
}
/// Consume self and build the ``DataChunk``.
pub fn build(mut self) -> Result<DataChunk, Error> {
if !self.digest_computed {
self.compute_digest();
}
let chunk = DataChunk::encode(
self.orig_data,
self.config,
self.digest,
self.compress,
)?;
Ok(chunk)
}
}