expose Argon2 options (as we did for bcrypt)

Signed-off-by: Arthur Schiwon <blizzz@arthur-schiwon.de>

config/config.sample.php

@@ -1433,6 +1433,31 @@ $CONFIG = array(
  */
 'tempdirectory' => '/tmp/nextcloudtemp',
 
+/**
+ * Hashing
+ *
+ * Nextcloud uses the Argon2 algorithm (with PHP >= 7.2) to create hashes by its
+ * own and exposes its configuration options as following. More information can
+ * be found at: https://www.php.net/manual/en/function.password-hash.php
+ */
+
+/**
+ * The allowed maximum memory to be used by the algorithm for computing a hash.
+ */
+'hashingMemoryCost' => PASSWORD_ARGON2_DEFAULT_MEMORY_COST,
+
+/**
+ * The allowed maximum time that can be used by the algorithm for computing a
+ * hash.
+ */
+'hashingTimeCost' => PASSWORD_ARGON2_DEFAULT_TIME_COST,
+
+/**
+ * The allowed number of CPU threads that can be used by the algorithm for
+ * computing a hash.
+ */
+'hashingThreads' => PASSWORD_ARGON2_DEFAULT_THREADS,
+
 /**
  * The hashing cost used by hashes generated by Nextcloud
  * Using a higher value requires more time and CPU power to calculate the hashes

lib/private/Security/Hasher.php

@@ -63,6 +63,12 @@ class Hasher implements IHasher {
 	public function __construct(IConfig $config) {
 		$this->config = $config;
 
+		$this->options = [
+			'memory_cost' => (int)$this->config->getSystemValue('hashingMemoryCost', PASSWORD_ARGON2_DEFAULT_MEMORY_COST),
+			'time_cost' => (int)$this->config->getSystemValue('hashingTimeCost', PASSWORD_ARGON2_DEFAULT_TIME_COST),
+			'threads' => (int)$this->config->getSystemValue('hashingThreads', PASSWORD_ARGON2_DEFAULT_THREADS),
+		];
+
 		$hashingCost = $this->config->getSystemValue('hashingCost', null);
 		if(!\is_null($hashingCost)) {
 			$this->options['cost'] = $hashingCost;