[Freeipa-devel] Time-Based Account Policies

[Stanislav Laznicka]

On 07/10/2015 01:12 PM, Matúš Honěk wrote:
> On 07/10/2015 12:43 PM, Alexander Bokovoy wrote:
>> On Fri, 10 Jul 2015, Stanislav Laznicka wrote:
>>> Hi,
>>>
>>> Long time no post from me, time to make it up to you.
>> Welcome back!
>>
>>> I have been working on the the implementation of the design of time
>>> policies for HBAC rules on FreeIPA and SSSD sides. Attached is the
>>> current state of the FreeIPA solution. My comments and notes to the
>>> solution follow.
>>>
>>> The FreeIPA side backend base for time policies in HBAC seems working
>>> to me but still needs formal testing. Also, there is no conversion
>>> from the iCal format as previously requested and I personally would
>>> postpone this feature until the time policies functionality is rock
>>> solid.
>>>
>>> There were some uncertainties in the design as well. I ran into 2 of
>>> these but more may come.
>>>
>>> The first thing is how to deal with weeks in a month. There are two
>>> possibilities. A week in month (as specified by the weekofmonth
>>> keyword in the time policies) may be understood as a period of time
>>> between two Sundays, so when a month starts on, say, Friday the 1st,
>>> weekofmonth=1 would specify days Friday, Saturday, Sunday and anything
>>> from that Sunday on would be a weekofmonth=2 and on. However, I think
>>> a week in a month may also be considered a period of time that equals
>>> 7 days of a month. In the previous example, a weekofmonth=1 would
>>> therefore also apply to the following days up until Friday the 8th,
>>> excluding this last day. Although I implemented the first case in the
>>> SSSD, I actually started thinking the second case scenario might be
>>> the right or "better" one.
>> One thing you need to realize that there is no universal 'week starts on
>> Sunday'.
>> There are different ways of starting a week, some countries do it on
>> Sunday, some -- on Saturday, some -- on Monday. This means you need to
>> make possible to pull in a locale definition if you really want this
>> functionality and then it also becomes quite fuzzy as there are legal
>> definitions of what a week is (as well as a month and a work day).
> I would definitely go with using the locales for deciding (same for 
> weeks of year, etc.). With addition to that I would, personally, also 
> make it clear to see the exact description of the policy currently in 
> use, on the WebUI and CLI (if it is possible, of course). Maybe it is 
> just me but I have no idea how to decide when is the first week of a 
> month, even in my locale. (if it is already there then act as if I 
> have said nothing)
>
I am not sure about using locales to decide on which day should start a 
week. It seems better to stick to only one certain day to avoid confusion.

I don't think it would be possible to have a note that says that this 
certain time policy applies at this certain time. It would be hard when 
only different time zones and UTC are taken into account, but the 
possibility to make time policy whose time zone is dependent purely on 
host's local time zone makes this impossible.

Petr V. posted a nice way of how to define a week earlier in this 
thread, even the first and 0-th week.
>>
>>> The other thing is which years should be allowed to be the input of
>>> the "year" keyword. Currently, I set the range for these values to
>>> 1970-2038 according to the Unix timestamp. I'm not sure if anyone
>>> would want to set it less than 1970, setting it for a higher value
>>> than 2038 might probably make sense in some very special cases,
>>> although I really can't think of a one.
>> You certainly can set it more than 2038 (time doesn't stop there). What
>> you are limited with is Kerberos 32-bit time stamp, not HBAC policy time
>> definition. I would say we better set to 64-bit ourselves and handle
>> irregularities in SSSD.
>>
>