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

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use std::convert::TryFrom;
use std::path::Path;
use anyhow::{bail, format_err, Error};
use serde_json::{json, Value};
use serde::{Deserialize, Serialize};
use crate::{BackupDir, CryptMode, CryptConfig, Fingerprint};
pub const MANIFEST_BLOB_NAME: &str = "index.json.blob";
pub const MANIFEST_LOCK_NAME: &str = ".index.json.lck";
pub const CLIENT_LOG_BLOB_NAME: &str = "client.log.blob";
pub const ENCRYPTED_KEY_BLOB_NAME: &str = "rsa-encrypted.key.blob";
mod hex_csum {
use serde::{self, Deserialize, Serializer, Deserializer};
pub fn serialize<S>(
csum: &[u8; 32],
serializer: S,
) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
let s = proxmox::tools::digest_to_hex(csum);
serializer.serialize_str(&s)
}
pub fn deserialize<'de, D>(
deserializer: D,
) -> Result<[u8; 32], D::Error>
where
D: Deserializer<'de>,
{
let s = String::deserialize(deserializer)?;
proxmox::tools::hex_to_digest(&s).map_err(serde::de::Error::custom)
}
}
fn crypt_mode_none() -> CryptMode { CryptMode::None }
fn empty_value() -> Value { json!({}) }
#[derive(Serialize, Deserialize)]
#[serde(rename_all="kebab-case")]
pub struct FileInfo {
pub filename: String,
#[serde(default="crypt_mode_none")] // to be compatible with < 0.8.0 backups
pub crypt_mode: CryptMode,
pub size: u64,
#[serde(with = "hex_csum")]
pub csum: [u8; 32],
}
impl FileInfo {
/// Return expected CryptMode of referenced chunks
///
/// Encrypted Indices should only reference encrypted chunks, while signed or plain indices
/// should only reference plain chunks.
pub fn chunk_crypt_mode (&self) -> CryptMode {
match self.crypt_mode {
CryptMode::Encrypt => CryptMode::Encrypt,
CryptMode::SignOnly | CryptMode::None => CryptMode::None,
}
}
}
#[derive(Serialize, Deserialize)]
#[serde(rename_all="kebab-case")]
pub struct BackupManifest {
backup_type: String,
backup_id: String,
backup_time: i64,
files: Vec<FileInfo>,
#[serde(default="empty_value")] // to be compatible with < 0.8.0 backups
pub unprotected: Value,
pub signature: Option<String>,
}
#[derive(PartialEq)]
pub enum ArchiveType {
FixedIndex,
DynamicIndex,
Blob,
}
impl ArchiveType {
pub fn from_path(archive_name: impl AsRef<Path>) -> Result<Self, Error> {
let archive_name = archive_name.as_ref();
let archive_type = match archive_name.extension().and_then(|ext| ext.to_str()) {
Some("didx") => ArchiveType::DynamicIndex,
Some("fidx") => ArchiveType::FixedIndex,
Some("blob") => ArchiveType::Blob,
_ => bail!("unknown archive type: {:?}", archive_name),
};
Ok(archive_type)
}
}
//#[deprecated(note = "use ArchivType::from_path instead")] later...
pub fn archive_type<P: AsRef<Path>>(
archive_name: P,
) -> Result<ArchiveType, Error> {
ArchiveType::from_path(archive_name)
}
impl BackupManifest {
pub fn new(snapshot: BackupDir) -> Self {
Self {
backup_type: snapshot.group().backup_type().into(),
backup_id: snapshot.group().backup_id().into(),
backup_time: snapshot.backup_time(),
files: Vec::new(),
unprotected: json!({}),
signature: None,
}
}
pub fn add_file(&mut self, filename: String, size: u64, csum: [u8; 32], crypt_mode: CryptMode) -> Result<(), Error> {
let _archive_type = ArchiveType::from_path(&filename)?; // check type
self.files.push(FileInfo { filename, size, csum, crypt_mode });
Ok(())
}
pub fn files(&self) -> &[FileInfo] {
&self.files[..]
}
pub fn lookup_file_info(&self, name: &str) -> Result<&FileInfo, Error> {
let info = self.files.iter().find(|item| item.filename == name);
match info {
None => bail!("manifest does not contain file '{}'", name),
Some(info) => Ok(info),
}
}
pub fn verify_file(&self, name: &str, csum: &[u8; 32], size: u64) -> Result<(), Error> {
let info = self.lookup_file_info(name)?;
if size != info.size {
bail!("wrong size for file '{}' ({} != {})", name, info.size, size);
}
if csum != &info.csum {
bail!("wrong checksum for file '{}'", name);
}
Ok(())
}
// Generate canonical json
fn to_canonical_json(value: &Value) -> Result<Vec<u8>, Error> {
pbs_tools::json::to_canonical_json(value)
}
/// Compute manifest signature
///
/// By generating a HMAC SHA256 over the canonical json
/// representation, The 'unpreotected' property is excluded.
pub fn signature(&self, crypt_config: &CryptConfig) -> Result<[u8; 32], Error> {
Self::json_signature(&serde_json::to_value(&self)?, crypt_config)
}
fn json_signature(data: &Value, crypt_config: &CryptConfig) -> Result<[u8; 32], Error> {
let mut signed_data = data.clone();
signed_data.as_object_mut().unwrap().remove("unprotected"); // exclude
signed_data.as_object_mut().unwrap().remove("signature"); // exclude
let canonical = Self::to_canonical_json(&signed_data)?;
let sig = crypt_config.compute_auth_tag(&canonical);
Ok(sig)
}
/// Converts the Manifest into json string, and add a signature if there is a crypt_config.
pub fn to_string(&self, crypt_config: Option<&CryptConfig>) -> Result<String, Error> {
let mut manifest = serde_json::to_value(&self)?;
if let Some(crypt_config) = crypt_config {
let sig = self.signature(crypt_config)?;
manifest["signature"] = proxmox::tools::digest_to_hex(&sig).into();
let fingerprint = &crypt_config.fingerprint();
manifest["unprotected"]["key-fingerprint"] = serde_json::to_value(fingerprint)?;
}
let manifest = serde_json::to_string_pretty(&manifest).unwrap();
Ok(manifest)
}
pub fn fingerprint(&self) -> Result<Option<Fingerprint>, Error> {
match &self.unprotected["key-fingerprint"] {
Value::Null => Ok(None),
value => Ok(Some(serde_json::from_value(value.clone())?))
}
}
/// Checks if a BackupManifest and a CryptConfig share a valid fingerprint combination.
///
/// An unsigned manifest is valid with any or no CryptConfig.
/// A signed manifest is only valid with a matching CryptConfig.
pub fn check_fingerprint(&self, crypt_config: Option<&CryptConfig>) -> Result<(), Error> {
if let Some(fingerprint) = self.fingerprint()? {
match crypt_config {
None => bail!(
"missing key - manifest was created with key {}",
fingerprint,
),
Some(crypt_config) => {
let config_fp = crypt_config.fingerprint();
if config_fp != fingerprint {
bail!(
"wrong key - manifest's key {} does not match provided key {}",
fingerprint,
config_fp
);
}
}
}
};
Ok(())
}
/// Try to read the manifest. This verifies the signature if there is a crypt_config.
pub fn from_data(data: &[u8], crypt_config: Option<&CryptConfig>) -> Result<BackupManifest, Error> {
let json: Value = serde_json::from_slice(data)?;
let signature = json["signature"].as_str().map(String::from);
if let Some(ref crypt_config) = crypt_config {
if let Some(signature) = signature {
let expected_signature = proxmox::tools::digest_to_hex(&Self::json_signature(&json, crypt_config)?);
let fingerprint = &json["unprotected"]["key-fingerprint"];
if fingerprint != &Value::Null {
let fingerprint = serde_json::from_value(fingerprint.clone())?;
let config_fp = crypt_config.fingerprint();
if config_fp != fingerprint {
bail!(
"wrong key - unable to verify signature since manifest's key {} does not match provided key {}",
fingerprint,
config_fp
);
}
}
if signature != expected_signature {
bail!("wrong signature in manifest");
}
} else {
// not signed: warn/fail?
}
}
let manifest: BackupManifest = serde_json::from_value(json)?;
Ok(manifest)
}
}
impl TryFrom<super::DataBlob> for BackupManifest {
type Error = Error;
fn try_from(blob: super::DataBlob) -> Result<Self, Error> {
// no expected digest available
let data = blob.decode(None, None)
.map_err(|err| format_err!("decode backup manifest blob failed - {}", err))?;
let json: Value = serde_json::from_slice(&data[..])
.map_err(|err| format_err!("unable to parse backup manifest json - {}", err))?;
let manifest: BackupManifest = serde_json::from_value(json)?;
Ok(manifest)
}
}
#[test]
fn test_manifest_signature() -> Result<(), Error> {
use crate::{KeyDerivationConfig};
let pw = b"test";
let kdf = KeyDerivationConfig::Scrypt {
n: 65536,
r: 8,
p: 1,
salt: Vec::new(),
};
let testkey = kdf.derive_key(pw)?;
let crypt_config = CryptConfig::new(testkey)?;
let snapshot: BackupDir = "host/elsa/2020-06-26T13:56:05Z".parse()?;
let mut manifest = BackupManifest::new(snapshot);
manifest.add_file("test1.img.fidx".into(), 200, [1u8; 32], CryptMode::Encrypt)?;
manifest.add_file("abc.blob".into(), 200, [2u8; 32], CryptMode::None)?;
manifest.unprotected["note"] = "This is not protected by the signature.".into();
let text = manifest.to_string(Some(&crypt_config))?;
let manifest: Value = serde_json::from_str(&text)?;
let signature = manifest["signature"].as_str().unwrap().to_string();
assert_eq!(signature, "d7b446fb7db081662081d4b40fedd858a1d6307a5aff4ecff7d5bf4fd35679e9");
let manifest: BackupManifest = serde_json::from_value(manifest)?;
let expected_signature = proxmox::tools::digest_to_hex(&manifest.signature(&crypt_config)?);
assert_eq!(signature, expected_signature);
Ok(())
}