Ensembia/nextcloud-ng_backup
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Fixes from the phase-1 code review

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- one locking protocol per location: backup steps and restores hold a
  shared lock, prune and untrash an exclusive one and refuse while any
  run (backup, restore, export) exists; starting a backup checks and
  creates the run under the exclusive lock, closing the race with prune
- snapshot entries are validated when read (relative path without '.',
  '..', NUL, backslash or control characters); raw restore also checks
  that the resolved directory stays below the target; the restore API
  and service accept canonical paths only
- recovery kit confirmation requires a recent password confirmation and
  the confirmation code printed in the current kit file (new code per
  kit version), proving the kit was actually downloaded
- prune decides on the authenticated index files on the location and
  refreshes the local index cache from them
- restore job marks the run failed on any error; restore runs without
  progress for 6 hours are failed so they cannot block cleanup forever
- tests for safe paths and a malicious snapshot path
This commit is contained in:
Dillard Blom
2026-10-02 11:21:40 +02:00
parent 9b03f98d0d
commit 7bde1cfdf0
14 changed files with 226 additions and 40 deletions
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lib/Service/KeyService.php
+32
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@@ -29,6 +29,7 @@ class KeyService {
private const KEY_FINGERPRINT = 'master_key_fingerprint';
private const KEY_DELETE_DELAY = 'delete_delay_days';
private const KEY_KIT_VERSION = 'recovery_kit_version';
private const KEY_KIT_CODE = 'recovery_kit_code';
public const DEFAULT_DELETE_DELAY = 7;
private ?KeyRing $cached = null;
@@ -188,6 +189,7 @@ class KeyService {
'app' => 'NG Backup',
'fingerprint' => $this->fingerprint(),
'kit_version' => $this->kitVersion(),
'confirmation_code' => $this->kitCode(),
'created' => gmdate('c'),
'wrapped_key' => $this->wrappedKey(),
'slots' => $this->slots(),
@@ -197,6 +199,36 @@ class KeyService {
];
}
/**
* Short code printed in the current kit file. Typing it back when confirming proves the
* admin actually has the downloaded kit. A new code per kit version; the server only keeps
* its own copy encrypted with the instance secret.
*/
private function kitCode(): string {
$stored = json_decode($this->appConfig->getValueString(Application::APP_ID, self::KEY_KIT_CODE, '{}', true), true) ?: [];
if (($stored['version'] ?? 0) === $this->kitVersion() && isset($stored['code'])) {
return $this->crypto->decrypt($stored['code']);
}
$alphabet = 'ABCDEFGHJKLMNPQRSTUVWXYZ23456789'; // no 0/O, 1/I
$code = '';
for ($i = 0; $i < 8; $i++) {
$code .= $alphabet[random_int(0, strlen($alphabet) - 1)];
}
$code = substr($code, 0, 4) . '-' . substr($code, 4);
$this->appConfig->setValueString(Application::APP_ID, self::KEY_KIT_CODE,
json_encode(['version' => $this->kitVersion(), 'code' => $this->crypto->encrypt($code)], JSON_THROW_ON_ERROR), true, true);
return $code;
}
public function checkKitCode(string $code): bool {
$stored = json_decode($this->appConfig->getValueString(Application::APP_ID, self::KEY_KIT_CODE, '{}', true), true) ?: [];
if (($stored['version'] ?? 0) !== $this->kitVersion() || !isset($stored['code'])) {
return false; // no kit downloaded for this version yet
}
$normalise = static fn (string $c) => strtoupper(preg_replace('/[^A-Za-z0-9]/', '', $c) ?? '');
return hash_equals($normalise($this->crypto->decrypt($stored['code'])), $normalise($code));
}
public function confirmRecoveryKit(string $uid): void {
$this->appConfig->setValueString(Application::APP_ID, self::KEY_CONFIRMED,
json_encode(['uid' => $uid, 'time' => time(), 'fingerprint' => $this->fingerprint(), 'kit_version' => $this->kitVersion()], JSON_THROW_ON_ERROR), true);