proxmox-backup/pbs-datastore/src/data_blob.rs

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use std::convert::TryInto;
use anyhow::{bail, Error};
use proxmox::tools::io::{ReadExt, WriteExt};
use super::file_formats::*;
use super::{CryptConfig, CryptMode};
const MAX_BLOB_SIZE: usize = 128*1024*1024;
/// Encoded data chunk with digest and positional information
pub struct ChunkInfo {
pub chunk: DataBlob,
pub digest: [u8; 32],
pub chunk_len: u64,
pub offset: u64,
}
/// Data blob binary storage format
///
/// Data blobs store arbitrary binary data (< 128MB), and can be
/// compressed and encrypted (or just signed). A simply binary format
/// is used to store them on disk or transfer them over the network.
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///
/// Please use index files to store large data files (".fidx" of
/// ".didx").
///
pub struct DataBlob {
raw_data: Vec<u8>, // tagged, compressed, encryped data
}
impl DataBlob {
/// accessor to raw_data field
pub fn raw_data(&self) -> &[u8] {
&self.raw_data
}
/// Returns raw_data size
pub fn raw_size(&self) -> u64 {
self.raw_data.len() as u64
}
/// Consume self and returns raw_data
pub fn into_inner(self) -> Vec<u8> {
self.raw_data
}
/// accessor to chunk type (magic number)
pub fn magic(&self) -> &[u8; 8] {
self.raw_data[0..8].try_into().unwrap()
}
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/// accessor to crc32 checksum
pub fn crc(&self) -> u32 {
let crc_o = proxmox::offsetof!(DataBlobHeader, crc);
u32::from_le_bytes(self.raw_data[crc_o..crc_o+4].try_into().unwrap())
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}
// set the CRC checksum field
pub fn set_crc(&mut self, crc: u32) {
let crc_o = proxmox::offsetof!(DataBlobHeader, crc);
self.raw_data[crc_o..crc_o+4].copy_from_slice(&crc.to_le_bytes());
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}
/// compute the CRC32 checksum
pub fn compute_crc(&self) -> u32 {
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let mut hasher = crc32fast::Hasher::new();
let start = header_size(self.magic()); // start after HEAD
hasher.update(&self.raw_data[start..]);
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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 blob has wrong CRC checksum.");
}
Ok(())
}
/// Create a DataBlob, optionally compressed and/or encrypted
pub fn encode(
data: &[u8],
config: Option<&CryptConfig>,
compress: bool,
) -> Result<Self, Error> {
if data.len() > MAX_BLOB_SIZE {
bail!("data blob too large ({} bytes).", data.len());
}
let mut blob = 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_BLOB_MAGIC_1_0)
} else {
(false, data, ENCRYPTED_BLOB_MAGIC_1_0)
}
} else {
(false, data, ENCRYPTED_BLOB_MAGIC_1_0)
};
let header_len = std::mem::size_of::<EncryptedDataBlobHeader>();
let mut raw_data = Vec::with_capacity(data.len() + header_len);
let dummy_head = EncryptedDataBlobHeader {
head: DataBlobHeader { 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 = EncryptedDataBlobHeader {
head: DataBlobHeader { magic, crc: [0; 4] }, iv, tag,
};
unsafe {
(&mut raw_data[0..header_len]).write_le_value(head)?;
}
DataBlob { raw_data }
} else {
let max_data_len = data.len() + std::mem::size_of::<DataBlobHeader>();
if compress {
let mut comp_data = Vec::with_capacity(max_data_len);
let head = DataBlobHeader {
magic: COMPRESSED_BLOB_MAGIC_1_0,
crc: [0; 4],
};
unsafe {
comp_data.write_le_value(head)?;
}
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zstd::stream::copy_encode(data, &mut comp_data, 1)?;
if comp_data.len() < max_data_len {
let mut blob = DataBlob { raw_data: comp_data };
blob.set_crc(blob.compute_crc());
return Ok(blob);
}
}
let mut raw_data = Vec::with_capacity(max_data_len);
let head = DataBlobHeader {
magic: UNCOMPRESSED_BLOB_MAGIC_1_0,
crc: [0; 4],
};
unsafe {
raw_data.write_le_value(head)?;
}
raw_data.extend_from_slice(data);
DataBlob { raw_data }
};
blob.set_crc(blob.compute_crc());
Ok(blob)
}
/// Get the encryption mode for this blob.
pub fn crypt_mode(&self) -> Result<CryptMode, Error> {
let magic = self.magic();
Ok(if magic == &UNCOMPRESSED_BLOB_MAGIC_1_0 || magic == &COMPRESSED_BLOB_MAGIC_1_0 {
CryptMode::None
} else if magic == &ENCR_COMPR_BLOB_MAGIC_1_0 || magic == &ENCRYPTED_BLOB_MAGIC_1_0 {
CryptMode::Encrypt
} else {
bail!("Invalid blob magic number.");
})
}
/// Decode blob data
pub fn decode(&self, config: Option<&CryptConfig>, digest: Option<&[u8; 32]>) -> Result<Vec<u8>, Error> {
let magic = self.magic();
if magic == &UNCOMPRESSED_BLOB_MAGIC_1_0 {
let data_start = std::mem::size_of::<DataBlobHeader>();
let data = self.raw_data[data_start..].to_vec();
if let Some(digest) = digest {
Self::verify_digest(&data, None, digest)?;
}
Ok(data)
} else if magic == &COMPRESSED_BLOB_MAGIC_1_0 {
let data_start = std::mem::size_of::<DataBlobHeader>();
let mut reader = &self.raw_data[data_start..];
let data = zstd::stream::decode_all(&mut reader)?;
// zstd::block::decompress is abou 10% slower
// let data = zstd::block::decompress(&self.raw_data[data_start..], MAX_BLOB_SIZE)?;
if let Some(digest) = digest {
Self::verify_digest(&data, None, digest)?;
}
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Ok(data)
} else if magic == &ENCR_COMPR_BLOB_MAGIC_1_0 || magic == &ENCRYPTED_BLOB_MAGIC_1_0 {
let header_len = std::mem::size_of::<EncryptedDataBlobHeader>();
let head = unsafe {
(&self.raw_data[..header_len]).read_le_value::<EncryptedDataBlobHeader>()?
};
if let Some(config) = config {
let data = if magic == &ENCR_COMPR_BLOB_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)?
};
if let Some(digest) = digest {
Self::verify_digest(&data, Some(config), digest)?;
}
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Ok(data)
} else {
bail!("unable to decrypt blob - missing CryptConfig");
}
} else {
bail!("Invalid blob magic number.");
}
}
/// Load blob from ``reader``, verify CRC
pub fn load_from_reader(reader: &mut dyn std::io::Read) -> Result<Self, Error> {
let mut data = Vec::with_capacity(1024*1024);
reader.read_to_end(&mut data)?;
let blob = Self::from_raw(data)?;
blob.verify_crc()?;
Ok(blob)
}
/// Create Instance from raw data
pub fn from_raw(data: Vec<u8>) -> Result<Self, Error> {
if data.len() < std::mem::size_of::<DataBlobHeader>() {
bail!("blob too small ({} bytes).", data.len());
}
let magic = &data[0..8];
if magic == ENCR_COMPR_BLOB_MAGIC_1_0 || magic == ENCRYPTED_BLOB_MAGIC_1_0 {
if data.len() < std::mem::size_of::<EncryptedDataBlobHeader>() {
bail!("encrypted blob too small ({} bytes).", data.len());
}
let blob = DataBlob { raw_data: data };
Ok(blob)
} else if magic == COMPRESSED_BLOB_MAGIC_1_0 || magic == UNCOMPRESSED_BLOB_MAGIC_1_0 {
let blob = DataBlob { raw_data: data };
Ok(blob)
} else {
bail!("unable to parse raw blob - wrong magic");
}
}
/// Returns if chunk is encrypted
pub fn is_encrypted(&self) -> bool {
let magic = self.magic();
magic == &ENCR_COMPR_BLOB_MAGIC_1_0 || magic == &ENCRYPTED_BLOB_MAGIC_1_0
}
/// Verify digest and data length for unencrypted chunks.
///
/// To do that, we need to decompress data first. Please note that
/// this is not possible for encrypted chunks. This function simply return Ok
/// for encrypted chunks.
/// Note: This does not call verify_crc, because this is usually done in load
pub fn verify_unencrypted(
&self,
expected_chunk_size: usize,
expected_digest: &[u8; 32],
) -> Result<(), Error> {
let magic = self.magic();
if magic == &ENCR_COMPR_BLOB_MAGIC_1_0 || magic == &ENCRYPTED_BLOB_MAGIC_1_0 {
return Ok(());
}
// verifies digest!
let data = self.decode(None, Some(expected_digest))?;
if expected_chunk_size != data.len() {
bail!("detected chunk with wrong length ({} != {})", expected_chunk_size, data.len());
}
Ok(())
}
fn verify_digest(
data: &[u8],
config: Option<&CryptConfig>,
expected_digest: &[u8; 32],
) -> Result<(), Error> {
let digest = match config {
Some(config) => config.compute_digest(data),
None => openssl::sha::sha256(data),
};
if &digest != expected_digest {
bail!("detected chunk with wrong digest.");
}
Ok(())
}
}
/// Builder for chunk DataBlobs
///
/// 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(ref 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 ``DataBlob``.
///
/// Returns the blob and the computet digest.
pub fn build(mut self) -> Result<(DataBlob, [u8; 32]), Error> {
if !self.digest_computed {
self.compute_digest();
}
let chunk = DataBlob::encode(self.orig_data, self.config, self.compress)?;
Ok((chunk, self.digest))
}
/// Create a chunk filled with zeroes
pub fn build_zero_chunk(
crypt_config: Option<&CryptConfig>,
chunk_size: usize,
compress: bool,
) -> Result<(DataBlob, [u8; 32]), Error> {
let zero_bytes = vec![0; chunk_size];
let mut chunk_builder = DataChunkBuilder::new(&zero_bytes).compress(compress);
if let Some(ref crypt_config) = crypt_config {
chunk_builder = chunk_builder.crypt_config(crypt_config);
}
chunk_builder.build()
}
}