add facilities to rehash on login passwords if parameters change

modoboa/core/password_hashers/base.py

@@ -86,6 +86,16 @@ class PasswordHasher(with_metaclass(MetaHasher, object)):
             hashed_value
         )
 
+    def needs_rehash(self, hashed_value):
+        """Check if the provided hash needs rehasing accoring to the current
+        parameters
+
+        :param str hashed_value: hased password
+        :rtype bool
+        :return: True if the password needs rehash, false otherwise
+        """
+        return False
+
     @classmethod
     def get_password_hashers(cls):
         """Return all the PasswordHasher supported by Modoboa"""

modoboa/core/views/auth.py

@@ -52,6 +52,14 @@ def dologin(request):
                         )
                         user.set_password(form.cleaned_data["password"])
                         user.save()
+                    if pwhash.needs_rehash(user.password):
+                        logging.info(
+                            _("Password hash parameter missmatch. "
+                              "Updating %s password"),
+                            user.username
+                        )
+                        user.set_password(form.cleaned_data["password"])
+                        user.save()
 
                 login(request, user)
                 if not form.cleaned_data["rememberme"]: