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src/backup/manifest.rs: cleanup signature generation

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This commit is contained in:
Dietmar Maurer
2020-07-09 09:20:49 +02:00
parent 152a926149
commit b53f637914
3 changed files with 169 additions and 73 deletions
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210
src/backup/manifest.rs
View File

@ -3,22 +3,56 @@ use std::convert::TryFrom;
use std::path::Path;
use serde_json::{json, Value};
use ::serde::{Deserialize, Serialize};
use crate::backup::{BackupDir, CryptMode, CryptConfig};
pub const MANIFEST_BLOB_NAME: &str = "index.json.blob";
pub const CLIENT_LOG_BLOB_NAME: &str = "client.log.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)
}
}
#[derive(Serialize, Deserialize)]
#[serde(rename_all="kebab-case")]
pub struct FileInfo {
pub filename: String,
pub crypt_mode: CryptMode,
pub size: u64,
#[serde(with = "hex_csum")]
pub csum: [u8; 32],
}
#[derive(Serialize, Deserialize)]
#[serde(rename_all="kebab-case")]
pub struct BackupManifest {
snapshot: BackupDir,
backup_type: String,
backup_id: String,
backup_time: i64,
files: Vec<FileInfo>,
pub unprotected: Value,
}
#[derive(PartialEq)]
@ -46,7 +80,13 @@ pub fn archive_type<P: AsRef<Path>>(
impl BackupManifest {
pub fn new(snapshot: BackupDir) -> Self {
Self { files: Vec::new(), snapshot }
Self {
backup_type: snapshot.group().backup_type().into(),
backup_id: snapshot.group().backup_id().into(),
backup_time: snapshot.backup_time().timestamp(),
files: Vec::new(),
unprotected: json!({}),
}
}
pub fn add_file(&mut self, filename: String, size: u64, csum: [u8; 32], crypt_mode: CryptMode) -> Result<(), Error> {
@ -84,65 +124,97 @@ impl BackupManifest {
Ok(())
}
pub fn signature(&self, crypt_config: &CryptConfig) -> [u8; 32] {
// Generate cannonical json
fn to_canonical_json(value: &Value, output: &mut String) -> Result<(), Error> {
match value {
Value::Null => bail!("got unexpected null value"),
Value::String(_) => {
output.push_str(&serde_json::to_string(value)?);
},
Value::Number(_) => {
output.push_str(&serde_json::to_string(value)?);
}
Value::Bool(_) => {
output.push_str(&serde_json::to_string(value)?);
},
Value::Array(list) => {
output.push('[');
for (i, item) in list.iter().enumerate() {
if i != 0 { output.push(','); }
Self::to_canonical_json(item, output)?;
}
output.push(']');
}
Value::Object(map) => {
output.push('{');
let mut keys: Vec<String> = map.keys().map(|s| s.clone()).collect();
keys.sort();
for (i, key) in keys.iter().enumerate() {
let item = map.get(key).unwrap();
if i != 0 { output.push(','); }
let mut data = String::new();
data.push_str(self.snapshot.group().backup_type());
data.push('\n');
data.push_str(self.snapshot.group().backup_id());
data.push('\n');
data.push_str(&format!("{}", self.snapshot.backup_time().timestamp()));
data.push('\n');
data.push('\n');
for info in self.files.iter() {
data.push_str(&info.filename);
data.push('\n');
data.push_str(match info.crypt_mode {
CryptMode::None => "None",
CryptMode::SignOnly => "SignOnly",
CryptMode::Encrypt => "Encrypt",
});
data.push('\n');
data.push_str(&format!("{}", info.size));
data.push('\n');
data.push_str(&proxmox::tools::digest_to_hex(&info.csum));
data.push('\n');
data.push('\n');
output.push_str(&serde_json::to_string(&Value::String(key.clone()))?);
output.push(':');
Self::to_canonical_json(item, output)?;
}
output.push('}');
}
}
crypt_config.compute_auth_tag(data.as_bytes())
Ok(())
}
pub fn into_json(self, crypt_config: Option<&CryptConfig>) -> 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> {
let mut manifest = json!({
"backup-type": self.snapshot.group().backup_type(),
"backup-id": self.snapshot.group().backup_id(),
"backup-time": self.snapshot.backup_time().timestamp(),
"files": self.files.iter()
.fold(Vec::new(), |mut acc, info| {
acc.push(json!({
"filename": info.filename,
"crypt-mode": info.crypt_mode,
"size": info.size,
"csum": proxmox::tools::digest_to_hex(&info.csum),
}));
acc
})
});
let mut signed_data = serde_json::to_value(&self)?;
signed_data.as_object_mut().unwrap().remove("unprotected"); // exclude
let mut canonical = String::new();
Self::to_canonical_json(&signed_data, &mut canonical)?;
let sig = crypt_config.compute_auth_tag(canonical.as_bytes());
Ok(sig)
}
/// Converts the Manifest into json string, and add a signature if there is a crypt_config.
pub fn into_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);
let sig = self.signature(crypt_config)?;
manifest["signature"] = proxmox::tools::digest_to_hex(&sig).into();
}
manifest
let manifest = serde_json::to_string_pretty(&manifest).unwrap().into();
Ok(manifest)
}
/// 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);
let manifest = BackupManifest::try_from(json)?;
if let Some(ref crypt_config) = crypt_config {
if let Some(signature) = signature {
let expected_signature = proxmox::tools::digest_to_hex(&manifest.signature(crypt_config)?);
if signature != expected_signature {
bail!("wrong signature in manifest");
}
} else {
// not signed: warn/fail?
}
}
Ok(manifest)
}
}
impl TryFrom<super::DataBlob> for BackupManifest {
type Error = Error;
@ -199,3 +271,45 @@ impl TryFrom<Value> for BackupManifest {
}
}
#[test]
fn test_manifest_signature() -> Result<(), Error> {
use crate::backup::{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.into_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::try_from(manifest)?;
let expected_signature = proxmox::tools::digest_to_hex(&manifest.signature(&crypt_config)?);
assert_eq!(signature, expected_signature);
Ok(())
}

12
src/bin/proxmox-backup-client.rs
View File

@ -1081,16 +1081,14 @@ async fn create_backup(
}
// create manifest (index.json)
let manifest = manifest.into_json(crypt_config.as_ref().map(Arc::as_ref));
// manifests are never encrypted, but include a signature
let manifest = manifest.into_string(crypt_config.as_ref().map(Arc::as_ref))
.map_err(|err| format_err!("unable to format manifest - {}", err))?;
println!("Upload index.json to '{:?}'", repo);
let manifest = serde_json::to_string_pretty(&manifest)?.into();
// manifests are never encrypted, but include a signature
// fixme: sign manifest
client
.upload_blob_from_data(manifest, MANIFEST_BLOB_NAME, true, false)
.upload_blob_from_data(manifest.into_bytes(), MANIFEST_BLOB_NAME, true, false)
.await?;
client.finish().await?;

20
src/client/backup_reader.rs
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@ -1,4 +1,4 @@
use anyhow::{bail, format_err, Error};
use anyhow::{format_err, Error};
use std::io::{Read, Write, Seek, SeekFrom};
use std::fs::File;
use std::sync::Arc;
@ -127,29 +127,13 @@ impl BackupReader {
/// The manifest signature is verified if we have a crypt_config.
pub async fn download_manifest(&self) -> Result<(BackupManifest, Vec<u8>), Error> {
use std::convert::TryFrom;
let mut raw_data = Vec::with_capacity(64 * 1024);
self.download(MANIFEST_BLOB_NAME, &mut raw_data).await?;
let blob = DataBlob::from_raw(raw_data)?;
blob.verify_crc()?;
let data = blob.decode(None)?;
let json: Value = serde_json::from_slice(&data[..])?;
let signature = json["signature"].as_str().map(String::from);
let manifest = BackupManifest::try_from(json)?;
if let Some(ref crypt_config) = self.crypt_config {
if let Some(signature) = signature {
let expected_signature = proxmox::tools::digest_to_hex(&manifest.signature(crypt_config));
if signature != expected_signature {
bail!("wrong signature in manifest");
}
} else {
// warn/fail?
}
}
let manifest = BackupManifest::from_data(&data[..], self.crypt_config.as_ref().map(Arc::as_ref))?;
Ok((manifest, data))
}