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[stable19] Harden SSE key generation #23755

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Merged
rullzer merged 3 commits into from
Oct 29, 2020
Merged

[stable19] Harden SSE key generation #23755

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dd4dc60
Harden key generation
juliusknorr Jul 22, 2020
c86e568
Test for locking state in key generation
juliusknorr Jul 27, 2020
7c98fbb
Fix typo in error message
MorrisJobke Aug 19, 2020
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Harden key generation 
There might be cases where multiple requests trigger the key generation
at the same time and the instance ends up with a non-fitting
public/private key pair. Therefore the whole key generation should be
locked. Other than that this makes sure that user key generation return
values are properly validated.

Signed-off-by: Julius Härtl <[email protected]>
  • Loading branch information
@juliusknorr @backportbot
juliusknorr authored and backportbot[bot] committed Oct 28, 2020
commit dd4dc60f4c9b7efa61b63fc4d8e4fd74c82cb8ce
3 changes: 2 additions & 1 deletion apps/encryption/lib/AppInfo/Application.php
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Original file line number Diff line number Diff line change
Expand Up @@ -152,7 +152,8 @@ function (IAppContainer $c) {
$server->getUserSession(),
new Session($server->getSession()),
$server->getLogger(),
$c->query('Util')
$c->query('Util'),
$server->getLockingProvider()
);
});

Expand Down
104 changes: 73 additions & 31 deletions apps/encryption/lib/KeyManager.php
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,7 @@
use OCP\IConfig;
use OCP\ILogger;
use OCP\IUserSession;
use OCP\Lock\ILockingProvider;

class KeyManager {

Expand Down Expand Up @@ -103,6 +104,11 @@ class KeyManager {
*/
private $util;

/**
* @var ILockingProvider
*/
private $lockingProvider;

/**
* @param IStorage $keyStorage
* @param Crypt $crypt
Expand All @@ -119,14 +125,16 @@ public function __construct(
IUserSession $userSession,
Session $session,
ILogger $log,
Util $util
Util $util,
ILockingProvider $lockingProvider
) {
$this->util = $util;
$this->session = $session;
$this->keyStorage = $keyStorage;
$this->crypt = $crypt;
$this->config = $config;
$this->log = $log;
$this->lockingProvider = $lockingProvider;

$this->recoveryKeyId = $this->config->getAppValue('encryption',
'recoveryKeyId');
Expand Down Expand Up @@ -161,17 +169,24 @@ public function __construct(
public function validateShareKey() {
$shareKey = $this->getPublicShareKey();
if (empty($shareKey)) {
$keyPair = $this->crypt->createKeyPair();

// Save public key
$this->keyStorage->setSystemUserKey(
$this->publicShareKeyId . '.publicKey', $keyPair['publicKey'],
Encryption::ID);

// Encrypt private key empty passphrase
$encryptedKey = $this->crypt->encryptPrivateKey($keyPair['privateKey'], '');
$header = $this->crypt->generateHeader();
$this->setSystemPrivateKey($this->publicShareKeyId, $header . $encryptedKey);
$this->lockingProvider->acquireLock('encryption-generateSharedKey', ILockingProvider::LOCK_EXCLUSIVE, 'Encryption: shared key generation');
try {
$keyPair = $this->crypt->createKeyPair();

// Save public key
$this->keyStorage->setSystemUserKey(
$this->publicShareKeyId . '.' . $this->publicKeyId, $keyPair['publicKey'],
Encryption::ID);

// Encrypt private key empty passphrase
$encryptedKey = $this->crypt->encryptPrivateKey($keyPair['privateKey'], '');
$header = $this->crypt->generateHeader();
$this->setSystemPrivateKey($this->publicShareKeyId, $header . $encryptedKey);
} catch (\Throwable $e) {
$this->lockingProvider->releaseLock('encryption-generateSharedKey', ILockingProvider::LOCK_EXCLUSIVE);
throw $e;
}
$this->lockingProvider->releaseLock('encryption-generateSharedKey', ILockingProvider::LOCK_EXCLUSIVE);
}
}

Expand All @@ -184,18 +199,36 @@ public function validateMasterKey() {
}

$publicMasterKey = $this->getPublicMasterKey();
if (empty($publicMasterKey)) {
$keyPair = $this->crypt->createKeyPair();

// Save public key
$this->keyStorage->setSystemUserKey(
$this->masterKeyId . '.publicKey', $keyPair['publicKey'],
Encryption::ID);

// Encrypt private key with system password
$encryptedKey = $this->crypt->encryptPrivateKey($keyPair['privateKey'], $this->getMasterKeyPassword(), $this->masterKeyId);
$header = $this->crypt->generateHeader();
$this->setSystemPrivateKey($this->masterKeyId, $header . $encryptedKey);
$privateMasterKey = $this->getPrivateMasterKey();

if (empty($publicMasterKey) && empty($privateMasterKey)) {
// There could be a race condition here if two requests would trigger
// the generation the second one would enter the key generation as long
// as the first one didn't write the key to the keystorage yet
$this->lockingProvider->acquireLock('encryption-generateMasterKey', ILockingProvider::LOCK_EXCLUSIVE, 'Encryption: master key generation');
try {
$keyPair = $this->crypt->createKeyPair();

// Save public key
$this->keyStorage->setSystemUserKey(
$this->masterKeyId . '.' . $this->publicKeyId, $keyPair['publicKey'],
Encryption::ID);

// Encrypt private key with system password
$encryptedKey = $this->crypt->encryptPrivateKey($keyPair['privateKey'], $this->getMasterKeyPassword(), $this->masterKeyId);
$header = $this->crypt->generateHeader();
$this->setSystemPrivateKey($this->masterKeyId, $header . $encryptedKey);
} catch (\Throwable $e) {
$this->lockingProvider->releaseLock('encryption-generateMasterKey', ILockingProvider::LOCK_EXCLUSIVE);
throw $e;
}
$this->lockingProvider->releaseLock('encryption-generateMasterKey', ILockingProvider::LOCK_EXCLUSIVE);
} elseif (empty($publicMasterKey)) {
$this->log->error('A private master key is available but the public key could not be found. This should never happen.');
return;
} elseif (empty($privateMasterKey)) {
$this->log->error('A private master key is available but the public key could not be found. This should never happen.');
return;
}

if (!$this->session->isPrivateKeySet()) {
Expand All @@ -222,7 +255,7 @@ public function recoveryKeyExists() {
* @return string
*/
public function getRecoveryKey() {
return $this->keyStorage->getSystemUserKey($this->recoveryKeyId . '.publicKey', Encryption::ID);
return $this->keyStorage->getSystemUserKey($this->recoveryKeyId . '.' . $this->publicKeyId, Encryption::ID);
}

/**
Expand All @@ -239,7 +272,7 @@ public function getRecoveryKeyId() {
* @return bool
*/
public function checkRecoveryPassword($password) {
$recoveryKey = $this->keyStorage->getSystemUserKey($this->recoveryKeyId . '.privateKey', Encryption::ID);
$recoveryKey = $this->keyStorage->getSystemUserKey($this->recoveryKeyId . '.' . $this->privateKeyId, Encryption::ID);
$decryptedRecoveryKey = $this->crypt->decryptPrivateKey($recoveryKey, $password);

if ($decryptedRecoveryKey) {
Expand All @@ -251,7 +284,7 @@ public function checkRecoveryPassword($password) {
/**
* @param string $uid
* @param string $password
* @param string $keyPair
* @param array $keyPair
* @return bool
*/
public function storeKeyPair($uid, $password, $keyPair) {
Expand All @@ -277,7 +310,7 @@ public function storeKeyPair($uid, $password, $keyPair) {
public function setRecoveryKey($password, $keyPair) {
// Save Public Key
$this->keyStorage->setSystemUserKey($this->getRecoveryKeyId().
'.publicKey',
'.' . $this->publicKeyId,
$keyPair['publicKey'],
Encryption::ID);

Expand Down Expand Up @@ -435,7 +468,7 @@ public function getFileKey($path, $uid) {
// use public share key for public links
$uid = $this->getPublicShareKeyId();
$shareKey = $this->getShareKey($path, $uid);
$privateKey = $this->keyStorage->getSystemUserKey($this->publicShareKeyId . '.privateKey', Encryption::ID);
$privateKey = $this->keyStorage->getSystemUserKey($this->publicShareKeyId . '.' . $this->privateKeyId, Encryption::ID);
$privateKey = $this->crypt->decryptPrivateKey($privateKey);
} else {
$shareKey = $this->getShareKey($path, $uid);
Expand Down Expand Up @@ -578,7 +611,7 @@ public function getPublicShareKeyId() {
* @return string
*/
public function getPublicShareKey() {
return $this->keyStorage->getSystemUserKey($this->publicShareKeyId . '.publicKey', Encryption::ID);
return $this->keyStorage->getSystemUserKey($this->publicShareKeyId . '.' . $this->publicKeyId, Encryption::ID);
}

/**
Expand Down Expand Up @@ -718,6 +751,15 @@ public function getMasterKeyId() {
* @return string
*/
public function getPublicMasterKey() {
return $this->keyStorage->getSystemUserKey($this->masterKeyId . '.publicKey', Encryption::ID);
return $this->keyStorage->getSystemUserKey($this->masterKeyId . '.' . $this->publicKeyId, Encryption::ID);
}

/**
* get public master key
*
* @return string
*/
public function getPrivateMasterKey() {
return $this->keyStorage->getSystemUserKey($this->masterKeyId . '.' . $this->privateKeyId, Encryption::ID);
}
}
4 changes: 2 additions & 2 deletions apps/encryption/lib/Users/Setup.php
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Expand Up @@ -73,8 +73,8 @@ public function __construct(ILogger $logger,
*/
public function setupUser($uid, $password) {
if (!$this->keyManager->userHasKeys($uid)) {
return $this->keyManager->storeKeyPair($uid, $password,
$this->crypt->createKeyPair());
$keyPair = $this->crypt->createKeyPair();
return is_array($keyPair) ? $this->keyManager->storeKeyPair($uid, $password, $keyPair) : false;
}
return true;
}
Expand Down
4 changes: 3 additions & 1 deletion apps/settings/lib/Controller/ChangePasswordController.php
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Expand Up @@ -188,7 +188,9 @@ public function changeUserPassword(string $username = null, string $password = n
\OC::$server->getUserSession(),
new \OCA\Encryption\Session(\OC::$server->getSession()),
\OC::$server->getLogger(),
$util);
$util,
\OC::$server->getLockingProvider()
);
$recovery = new \OCA\Encryption\Recovery(
\OC::$server->getUserSession(),
$crypt,
Expand Down