[Freeipa-devel] Sudorules user validation help

[Martin Kosek]

On 05/28/2015 04:27 PM, Drew Erny wrote:
> In the ticket, however, it's stated that if the user wants to use any
> combination of weird characters, they should be able to. Would it be better to
> just define a function like
> 
> def validate_username(username, ignore_pattern=False):
> 
> and have it ignore all username validation?

Tough question. FreeIPA in general tries to sanitize user input and does not
allow everything user wants and try to advise the best practices, as we see it.

In your case, if we allow only the 2 mentioned user login formats, it should
work for AD use case just fine and add some level of sanity check of the user
name. BTW, given we run an LDAP search later on this user name, isn't there a
possibility of "LDAP injection" if we choose to allow all characters, including
"(" and ")"? :-)

In any case, if we choose to ignore the pattern, we do not need the extra
validator function at all. We would just skip validation in the pre callback if
a user is being added.

> 
> On 05/28/2015 09:40 AM, Drew Erny wrote:
>> OK, I see now what you mean by that. That is a simpler solution. I'll do it
>> that way.
>>
>> On 05/28/2015 04:44 AM, Martin Kosek wrote:
>>> On 05/27/2015 08:41 PM, Drew Erny wrote:
>>>> Hey, Freeipa-devel,
>>>>
>>>> I'm working on ticket #3226 (https://fedorahosted.org/freeipa/ticket/3226)
>>>>
>>>> I've identified the problem. The sudorules add user command adds the user
>>>> validations at the end of it's pre-callback using add_external_pre_callback.
>>>> However, the "user" plugin pattern-matches a string for the "uid" param,
>>>> because it only allows certain characters.
>>>>
>>>> I've been picking through the codebase and I think I have enough understanding
>>>> to ask this: What if we changed the user "uid" validation to a standalone
>>>> "rule" function (you can do that, right? pass in a function as a validation
>>>> rule?) that would normally just assert that the pattern matches, but could
>>>> have
>>>> that pattern matching validation overridden in some cases. I think that's the
>>>> easiest, cleanest way to change user so that sudorules and other plugins can
>>>> ignore this validation if necessary (I'm trying to figure out exactly how to
>>>> implement this without changing any APIs).
>>>>
>>>> Am I understanding the plugin params API correctly, and can I do this? Is this
>>>> the best way to do this?
>>>>
>>>> The only other solution I see is to write sudorules-specific code in some
>>>> plugin-related (either user.py or baseldap.py module, which would create
>>>> unwanted coupling.
>>>>
>>>> Most specifically, this would be a change to the object instantiated at
>>>> ipalib/plugins/user.py line 467
>>>>
>>>> Thoughts and suggestions?
>>> I think it would make sense to follow the example with validate_hostname and
>>> prepare a function validate_username(username, upn=False,
>>> netbios_name=False) [1].
>>>
>>> where upn would allow using "@." on top of current validator (i.e.
>>> user at Domain.test) and netbios_name would allow the "DOMAIN\user" style. I would
>>> just suggest making sure the standard user validation error message is still
>>> the same to avoid unnecessary QE fail positives.
>>>
>>> In add_external_pre_callback you could then just simply call
>>>
>>> validate_username(user, True, True)
>>>
>>> just like it is already done with hostname.
>>>
>>> My 2 cents.
>>>
>>> Martin
>>>
>>> [1]
>>> https://msdn.microsoft.com/en-us/library/windows/desktop/aa380525(v=vs.85).aspx
>>
>