Hi all, Thanks for all the feedback. Good to see this seems to be heading in the right direction. The suggestions make sense to me and I’ll work on those.
There were two particular design suggestions: instead of tying the validator to the password field, tying this to the authentication backend, which would prevent having to add a setting, and allow different security requirements for different backends. Another suggestion was to add configurable password fields instead, which could also include other functionality. My concern with tying the validator to the auth backend instead, is that it would mean there is absolutely no way to circumvent the validation, whereas in the current scenario I’ve intentionally not included validation in User.set_password() by default - but only in the user-facing elements. I think it will be easier to get wider adoption of password validation, if we still leave an opportunity open to avoid it in special cases. Also, I’m not sure whether we could still easily and cleanly provide the appropriate help text to the user. If someone would want validation that depends on the auth backend, this is possible with undocumented APIs. If my memory serves me right, the user object that the validator has access to will have an attribute that identifies the backend used to authenticate the user. The validator could make different choices based on that, or even call a method on a backend. That’s not with a currently documented API though. Replaceable password fields are themselves interesting, but I think it would be too limited for password validation in general. A specific wish was to also be able to tie validation into a REST API, for example. The current validator design allows trivial integration of a validator into absolutely anything. Custom password fields are already not too hard - all you have to do is create your own form, override the password fields and pass that form to the appropriate views. It’s not even necessary to write your own views. We could make that process simpler if the other benefits of custom password fields are relevant enough, but I don’t think they’re the best design for the validation problem. Erik > On 11 Mar 2015, at 09:52, Tino de Bruijn <[email protected]> wrote: > > Hi Erik, I like the way this is going! > > I do want to emphasise the point that Josh made: you have to be able to > aggregate all ValidationErrors, otherwise things can become quite > frustrating. (Try to change your Skype password and you know why...) > > Tino > > On Wed, Mar 11, 2015 at 1:44 AM, Josh Smeaton <[email protected] > <mailto:[email protected]>> wrote: > Great stuff Erik. This will greatly simplify how we validate passwords! > > One thing I'd like to note is that it is extremely frustrating when a form > fails validation with an error message, you fix that particular problem, and > you're given the next error message. Ideally, all validators would run and > spit out all of the error messages in one go. Then the user is given a chance > to correct all problems at once rather than a submit and hope game. I took a > look at the implementation and I don't think this is supported. Would it be > possible to aggregate all of the ValidationErrors? > > Cheers > > > On Monday, 9 March 2015 01:48:00 UTC+11, Erik Romijn wrote: > Hello all, > > I've taken another stab at 16860[1]: having a password validation/policy in > Django. I've made an initial simple PR[2] to show the approach I'd like to > use - no tests or documentation yet, the example validators are not very > nice, possibly bad naming, etc. But this should be sufficient to show how I > would like to tackle this. There's quite a few decisions to take, influencing > the later possibilities, which I'll try to outline below. > > Users choosing awful passwords is a serious security issue. Although password > validation can only go so far - especially to the extent that we can > implement in Django itself - to me it seems part of our responsibility in > helping Django developers to build safer websites. > > First, let me briefly describe my approach: we add a new setting to define > zero or more password validator classes. Optionally, a class can be provided > with custom arguments to it's constructor. Each validator class has a > help_text() method and a validate(password, user) method. The former produces > a translatable sentence to be included in the form field's help text. The > validate method validates a certain password, optionally taking the context > of a user into account and passes its judgement on the password. If a > validator considers a password insufficient, it raises a ValidationError. > > This is tied to the validation and form field setup in SetPasswordForm and > AdminPasswordChangeForm. An obvious choice seems to be to tie this to > User.set_password(). However, I intentionally did not include that step, as I > feel this validation should primarily take place on the user frontend site > with forms. This mirrors the way we typically handle this in Django. Should > someone feel different, and want to tie this to set_password() as well, this > is possible with a custom user object. Tying this validation into any other > place is also trivial: just adding a single line. > > I decided not to go for standard Django validators, as I felt this would > offer insufficient flexibility and configurability - as was already raised in > previous discussions on this issue. > > In the ticket, Shai described a few particular goals for this feature: > > - Informing the user of the various password requirements: this is possible > by each validator providing a description, which can be dependent on it's > configuration, of it's requirements. Independent sentences from different > validators are now concatenated, an approach which will not always yield the > prettiest language. > - Allowing policies to chain together smoothly: multiple validators can be > run sequentially, stopping after the first failure. > - Provide flexibility for complex requirements (some may include their own > models): this is entirely possible within the design. > - Backwards compatibility: the default setting is to have no validators, > which means no change and no modifications in help text. I do suggest we > include some reasonable defaults in the standard project template. > - Javascript validation assistance or HTML5 support: not implemented > currently, but this could be added in a similar way as help texts. > - Prevent using email, username or other user attributes as (part of) > passwords: where possible, the user object is passed to the validator. > There's a (not pretty) example of this in the PR. > - Prevent reuse of old passwords: it is possible in the design for a > validator to store all passwords it saw. I have doubts on whether this would > be a good approach though. > > So I think this design makes it simple to have sane defaults for new > projects, extensive configurability while keeping simple scenarios simple to > configure, and easy extensibility with third party password validators > (zxcvbn comes to mind). I'd love to hear any feedback and ideas you may have. > > Erik > > > [1] https://code.djangoproject.com/ticket/16860 > <https://code.djangoproject.com/ticket/16860> > [2] https://github.com/django/django/pull/4276 > <https://github.com/django/django/pull/4276> > > -- > You received this message because you are subscribed to the Google Groups > "Django developers (Contributions to Django itself)" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:[email protected]>. > To post to this group, send email to [email protected] > <mailto:[email protected]>. > Visit this group at http://groups.google.com/group/django-developers > <http://groups.google.com/group/django-developers>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-developers/3a0b87ad-5073-4af1-8a7a-cd91705e287a%40googlegroups.com > > <https://groups.google.com/d/msgid/django-developers/3a0b87ad-5073-4af1-8a7a-cd91705e287a%40googlegroups.com?utm_medium=email&utm_source=footer>. > > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. > > > -- > You received this message because you are subscribed to the Google Groups > "Django developers (Contributions to Django itself)" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:[email protected]>. > To post to this group, send email to [email protected] > <mailto:[email protected]>. > Visit this group at http://groups.google.com/group/django-developers > <http://groups.google.com/group/django-developers>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-developers/CANQFsQATUqV1CfsnAdjrvAQgHs0eQ-zx7pVC%2Bg9KvDiQ7mFbYQ%40mail.gmail.com > > <https://groups.google.com/d/msgid/django-developers/CANQFsQATUqV1CfsnAdjrvAQgHs0eQ-zx7pVC%2Bg9KvDiQ7mFbYQ%40mail.gmail.com?utm_medium=email&utm_source=footer>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/django-developers. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/24FEB9D0-03ED-4CD6-81D4-E5A981C6BFE3%40solidlinks.nl. For more options, visit https://groups.google.com/d/optout.
signature.asc
Description: Message signed with OpenPGP using GPGMail
