Ensembia/nextcloud-ng_backup
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M5: chained catalog against rollback and hidden snapshots

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Every change to the set of snapshots or trash entries writes an
encrypted catalog generation bound to the repository and its position,
with the hash of the previous generation. The server anchors the newest
generation it has seen in its app config; on open, the location must
show at least that generation and chain back to it, and every snapshot
listed must exist. A rolled-back or tampered location is refused (the
run fails and administrators are notified). Opening with the passphrase
on a new server accepts the newest valid chain.

occ backup:target:trust-current accepts a legitimately older state
(e.g. restored from the provider's snapshot) after typing the location
name; audited and announced to all administrators.

Tests: chain advances, rollback, hidden snapshot, swapped generation,
disaster recovery without anchor. Tested on NC34 by deleting the newest
catalog generation on the SFTP location.
This commit is contained in:
Dillard Blom
2026-10-02 11:30:42 +02:00
parent 8b822a73ac
commit 62e365350f
9 changed files with 392 additions and 11 deletions
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lib/Repository/Repository.php
+55 -7
View File
@@ -32,6 +32,7 @@ final class Repository {
private StreamCipher $cipher;
private BlobIndex $index;
private ?PackWriter $runPacks = null;
private Catalog $catalog;
private function __construct(
private IBackend $backend,
@@ -52,7 +53,7 @@ final class Repository {
* copy (KeyRing::wrap) stored in the repository config, so the repository can be opened
* with the passphrase from the recovery kit even when the server is gone.
*/
public static function initWithKey(IBackend $backend, KeyRing $keys, array $wrappedKey): self {
public static function initWithKey(IBackend $backend, KeyRing $keys, array $wrappedKey, ?ICatalogAnchor $anchor = null): self {
if ($backend->exists('config')) {
throw new RepositoryException('A repository already exists at this location');
}
@@ -60,11 +61,13 @@ final class Repository {
$config = ['format' => self::FORMAT, 'id' => $id, 'created' => gmdate('c'), 'key' => $wrappedKey,
'check' => base64_encode((new StreamCipher($keys))->encryptString($id, 'config-check'))];
self::putString($backend, 'config', json_encode($config, JSON_PRETTY_PRINT | JSON_THROW_ON_ERROR));
return new self($backend, $keys, $id);
$repo = new self($backend, $keys, $id);
$repo->loadCatalog($anchor);
return $repo;
}
/** Open with the master key the server holds (scheduled backups, no passphrase needed). */
public static function openWithKey(IBackend $backend, KeyRing $keys, ?IIndexCache $cache = null): self {
public static function openWithKey(IBackend $backend, KeyRing $keys, ?IIndexCache $cache = null, ?ICatalogAnchor $anchor = null): self {
$config = self::readConfig($backend);
try {
$ok = isset($config['check']) && (new StreamCipher($keys))->decryptString((string)base64_decode($config['check'], true), 'config-check') === $config['id'];
@@ -79,9 +82,22 @@ final class Repository {
$repo->index->setCache($cache, $config['id']);
}
$repo->index->load();
$repo->loadCatalog($anchor);
return $repo;
}
private function loadCatalog(?ICatalogAnchor $anchor): void {
$this->catalog = new Catalog($this->backend, $this->cipher, $this->repositoryId, $anchor);
$this->catalog->load(
fn () => array_map('basename', $this->backend->list('snapshots')),
fn () => array_map('basename', $this->backend->list('trash/info')));
}
/** Current catalog generation (for status and tests). */
public function catalogGeneration(): int {
return $this->catalog->gen;
}
/** Index files downloaded when this repository was opened (0 when the local cache was complete). */
public function indexDownloads(): int {
return $this->index->downloaded;
@@ -116,6 +132,7 @@ final class Repository {
$config = self::readConfig($backend);
$repo = new self($backend, KeyRing::unwrapAny($config['key'], $passphrase), $config['id']);
$repo->index->load();
$repo->loadCatalog(null); // disaster recovery on a new server: no anchor yet, trust the newest valid chain
return $repo;
}
@@ -156,6 +173,8 @@ final class Repository {
rewind($encrypted);
$this->backend->put('snapshots/' . $snapshotId, $encrypted);
fclose($tree);
$this->catalog->snapshots[$snapshotId] = true;
$this->catalog->write();
return ['snapshot' => $snapshotId] + $stats;
}
@@ -263,6 +282,8 @@ final class Repository {
fclose($tree);
rewind($encrypted);
$this->backend->put('snapshots/' . $snapshotId, $encrypted);
$this->catalog->snapshots[$snapshotId] = true;
$this->catalog->write();
}
/** @return array<string, array{s:int, m:int, b:list<string>}> */
@@ -321,6 +342,9 @@ final class Repository {
$this->backend->put('trash/snapshots/' . $snapshotId, $this->backend->get('snapshots/' . $snapshotId));
$this->putObject('trash/info/' . $snapshotId, json_encode(['forgottenAt' => time(), 'by' => $by, 'db' => $meta['db'] ?? null,
'dbInTrash' => $dbInTrash, 'time' => $meta['time'] ?? null, 'label' => $meta['label'] ?? ''], JSON_THROW_ON_ERROR));
unset($this->catalog->snapshots[$snapshotId]);
$this->catalog->trash[$snapshotId] = true;
$this->catalog->write();
if ($dbInTrash !== null) {
$this->backend->delete($meta['db']);
}
@@ -335,6 +359,9 @@ final class Repository {
$this->backend->delete($info['dbInTrash']);
}
$this->backend->put('snapshots/' . $snapshotId, $this->backend->get('trash/snapshots/' . $snapshotId));
$this->catalog->snapshots[$snapshotId] = true;
unset($this->catalog->trash[$snapshotId]);
$this->catalog->write();
$this->backend->delete('trash/snapshots/' . $snapshotId);
$this->backend->delete('trash/info/' . $snapshotId);
}
@@ -342,8 +369,12 @@ final class Repository {
/** @return array<string, array{forgottenAt:int, by:string, db:?string, dbInTrash:?string, time:?string, label:string}> */
public function trash(): array {
$out = [];
foreach ($this->backend->list('trash/info') as $path) {
$out[basename($path)] = $this->trashInfo(basename($path));
foreach (array_keys($this->catalog->trash) as $id) {
try {
$out[$id] = $this->trashInfo($id);
} catch (\Throwable) {
throw new RepositoryException("Trash entry $id listed in the catalog is missing on the location (possible tampering)");
}
}
return $out;
}
@@ -360,8 +391,12 @@ final class Repository {
}
$this->backend->delete('trash/snapshots/' . $id);
$this->backend->delete('trash/info/' . $id);
unset($this->catalog->trash[$id]);
$purged[] = $id;
}
if ($purged !== []) {
$this->catalog->write();
}
return $purged;
}
@@ -470,9 +505,22 @@ final class Repository {
return $stats;
}
/** @return list<string> */
/**
* Snapshots according to the verified catalog. A snapshot the catalog lists but the location
* no longer has means it was deleted or hidden behind NG Backup's back.
*
* @return list<string>
*/
public function listSnapshots(): array {
return array_map('basename', $this->backend->list('snapshots'));
$present = array_flip(array_map('basename', $this->backend->list('snapshots')));
$listed = array_keys($this->catalog->snapshots);
foreach ($listed as $id) {
if (!isset($present[$id])) {
throw new RepositoryException("Snapshot $id is missing on the location (deleted or hidden outside NG Backup)");
}
}
sort($listed);
return $listed;
}
public function blobCount(): int {