Validate user passwords in DB managers

Also, make the validateParameter method ignore null parameters, e.g. for cases when tenants are created using Tenant::make() without tenancy_db_username set -- $databaseConfig->getUsername() allows null, same should go for the validate method whose only concern is checking strings for invalid characters.

src/Database/Concerns/ManagesPostgresUsers.php

@@ -28,8 +28,8 @@ trait ManagesPostgresUsers
         $username = $databaseConfig->getUsername();
         $password = $databaseConfig->getPassword();
 
-        // todo@validation password
         $this->validateParameter($username);
+        $this->validatePassword($password);
 
         $createUser = ! $this->userExists($username);
 

src/Database/Concerns/ValidatesSqlParameters.php

@@ -18,22 +18,58 @@ trait ValidatesSqlParameters
         return 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_-';
     }
 
+    /**
+     * Characters allowed in database user passwords.
+     *
+     * Passwords are always quoted in the SQL statements, so it's safe
+     * to allow a wider range of characters, as long as it doesn't include
+     * characters that can break out of the quoted SQL strings (so e.g.
+     * ', ", \, and ` aren't allowed).
+     */
+    protected static function passwordAllowlist(): string
+    {
+        return ' !#$%&()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[]^_abcdefghijklmnopqrstuvwxyz{|}~';
+    }
+
     /**
      * Validate that parameters (database names, usernames, etc.)
-     * contain only allowed characters before used in SQL statements.
+     * only contain allowed characters before used in SQL statements.
+     *
+     * By default, only the characters in static::parameterAllowlist() are allowed.
      *
      * @throws InvalidArgumentException
      */
-    protected function validateParameter(string|array $parameters): string|array
+    protected function validateParameter(string|array|null $parameters, string|null $allowlist = null): string|array|null
     {
+        if (is_null($parameters)) {
+            // Return null if there's nothing to validate
+            // (e.g. when $databaseConfig->getUsername() of an
+            // improperly created tenant is passed).
+            return null;
+        }
+
+        $allowlist = $allowlist ?? static::parameterAllowlist();
+
         foreach ((array) $parameters as $parameter) {
             foreach (str_split($parameter) as $char) {
-                if (! str_contains(static::parameterAllowlist(), $char)) {
+                if (! str_contains($allowlist, $char)) {
-                    throw new InvalidArgumentException("Invalid character '{$char}' in SQL parameter: {$parameter}");
+                    throw new InvalidArgumentException("Invalid character '{$char}' in parameter: {$parameter}");
                 }
             }
         }
 
         return $parameters;
     }
+
+    /**
+     * Validate that a password only contains allowed characters before used in SQL statements.
+     *
+     * Used as a shorthand for validateParameter() with the less strict allowlist.
+     *
+     * @throws InvalidArgumentException
+     */
+    protected function validatePassword(string|null $password): string|null
+    {
+        return $this->validateParameter($password, static::passwordAllowlist());
+    }
 }

src/Database/TenantDatabaseManagers/PermissionControlledMicrosoftSQLServerDatabaseManager.php

@@ -24,8 +24,8 @@ class PermissionControlledMicrosoftSQLServerDatabaseManager extends MicrosoftSQL
         $username = $databaseConfig->getUsername();
         $password = $databaseConfig->getPassword();
 
-        // todo@validation password
         $this->validateParameter([$database, $username]);
+        $this->validatePassword($password);
 
         // Create login
         $this->connection()->statement("CREATE LOGIN [$username] WITH PASSWORD = '$password'");

src/Database/TenantDatabaseManagers/PermissionControlledMySQLDatabaseManager.php

@@ -25,8 +25,8 @@ class PermissionControlledMySQLDatabaseManager extends MySQLDatabaseManager impl
         $username = $databaseConfig->getUsername();
         $password = $databaseConfig->getPassword();
 
-        //todo@validation password
         $this->validateParameter([$database, $username]);
+        $this->validatePassword($password);
 
         $this->connection()->statement("CREATE USER `{$username}`@`%` IDENTIFIED BY '{$password}'");