Hello everyone,
I have been looking into PR #495
https://github.com/IdentityPython/pysaml2/pull/495
What the user needs is an option to configure the signing algorithm
that will be used by the SP to sign an authentication request. This
comes in hand with the digest algorithm and in extension what is
entity that should be signed.
What the proposed one line change does, is allows this value to exist
in pysaml2 Config object. By itself, it does not affect anything in
the code - it does not set the signing algorithm. It is only a
placeholder for a value. Something else is supposed to look at that
value, at the right time, and pass it as an argument to the
appropriate function/method.
This doesn't seem right. If it is in the configuration, then it should
actually do something - it should affect the way the library behaves.
Looking into this I stumbled upon some commits, made about a year ago,
that implement some of this functionality for the IdP part:
* 2aedfa0 - make both sign response and assertion configurable
adds sign_assertion and sign_response options
* bd4303a - Signing signature and digest algorithm configuration
adds sign_alg and digest_alg options
These are implemented in the SATOSA repository (see
satosa/frontends/saml2.py the _handle_authn_response method). However,
their configuration lies between the lines of the pysaml2
configuration (under service/idp/policy). This is wrong - each project
should be responsible for its own configuration. The code that decides
what should be signed and how, should live in pysaml2. If it is
handled by SATOSA then it should be part of the SATOSA configuration
and an override of the pysaml2 configuration.
Moreover, it seems that this functionality was partially already there
in pysaml2 in the first place. See the Policy class in
saml2/assertion.py and its get_sign method. An option named 'sign' can
be defined under the service/idp/policy part of the configuration,
that defines an array of values that represent what should be signed,
for example:
service:
idp:
policy:
sign:
- response
- assertion
So now we have both the above 'sign' option, plus 'sign_assertion' and
'sign_response', which should do the same thing.
What I would like to do is move the code introduced by the commits
above into pysaml2: this will allow a consistent behaviour whether
pysaml2 is used by SATOSA or some other project. Then the same options
can be used by the backend too, which would satisfy the user request.
Once that is done we can look into making the configuration work in
one way.
This is bigger than it looks. What happens now is that we define for
example, that we want to use SHA512 as a sign_alg. This will be used
when a authentication response is formed, but it is ignored when for
example a logout request is to be created. This happens because the
configuration of what signing algorithm will be used is only
implemented for the authentication response.
There are two ways to fix this:
- we either assume that a configuration option like 'sign_alg' is
global, and as such, it affects the signing algorithm of anything that
is to be signed
- or we assume that it relates to the authentication req/response only
(and in that case it shold probably be called authn_sign_alg or alike)
and require new options for other kinds of signatures
(logout_sign_alg, metadata_sign_alg, etc).
The first solution requires that we find all places in the code use
signatures and make sure they respect the configuration. I have
already noted (a lot of) entry points to pysaml2 that should be
looking into the configuration to derive the signing and digest
algorithm values.
The second option is "easier" to work with, as it allows for an
incremental implementation of this request. The second approach is
also more flexible for the end user, but at the same time more complex
as it requires more configuration values to be set.
Ofcourse we can have both, use an option like sign_alg to defined the
signing algorithm, and use "suboptions" like authn_sign_alg to
override the sign_alg setting where needed.
I hope this makes sense (even though it mixes at least four
configuration options together). If you have any comments, I'd like to
hear.
Cheers,
--
Ivan c00kiemon5ter Kanakarakis >:3
Hi,
On the last DEV call we talked about moving to using type hints.
The typing module was added in Python 3.5, but as of today SATOSA still
supports Python 3.4.
I apologize if I missed it, but did we discuss stopping support for
Python 3.4? If so, when?
Thanks,
Scott
Hi,
I have a response microservice that needs some information that only the
frontend knows.
>From what I can tell, there is no way for the microservice to get a hook
into the frontend in order to gather the information.
Am I missing something?
Thanks,
Scott K
Hi,
To summarize:
- SATOSA_STATE in its original design is a straight link between SSO request and response. After the frontend created the Response the _save_state call will delete the cookie.
- To remember the selected IDP SATOSA_STATE across over the long term state can be kept by setting CONTEXT_STATE_DELETE=False
I think that it could make sense to separate short- and long-running state cookies. For my current use case (requiring a replay of the previous AuthnRequest during Response processing in the backend) I decided to create a separate cookie, which is in fact a key into a local Redis store. It has a life cycle different, longer than a straight Response, but not across SSO flows.
BTW, shouldn’t the proxy set HttpOnly and SameSite=Strict for SATOSA_STATE?
Cheers, Rainer
> Am 2019-06-05 um 00:27 schrieb Christos Kanellopoulos <christos.kanellopoulos at geant.org>:
>
> Hello,
>
> for question (b) indeed there is a point to do that. If one wants to keep state across authentication requests, then SATOSA needs to search for the cookie also in the AuthN request and load the context if it is found and it is valid. For example, in PR #234 we add the option to save the selected IdP in the cookie so that in the follow up AuthN requests SATOSA can skip the discovery. Having said this, it’s been a year since I touched that code so Ivan please correct me if I am wrong.
>
> Christos
>
> From: Rainer Hoerbe <rainer at hoerbe.at>
> Sent: Friday, May 31, 2019 12:42 PM
> To: Ivan Kanakarakis; Christos Kanellopoulos
> Cc: satosa-dev at lists.sunet.se
> Subject: SATOSA_STATE
>
>
> I summarized the handling SATOSA_STATE as discussed in Tuesday’s meeting in the attached diagrams. I have two questions:
>
> a) Is this picture correct?
> b) Is there any purpose in loading the context from SATOSA_STATE when an AuthnRequest is received?
>
> Thanks, Rainer
>
>
>> Am 2019-05-30 um 13:09 schrieb Ivan Kanakarakis <ivan.kanak at gmail.com <mailto:ivan.kanak at gmail.com>>:
>>
>>
>> On Wed, 29 May 2019 at 23:28, Rainer Hoerbe <rainer at hoerbe.at <mailto:rainer at hoerbe.at>> wrote:
>>
>>>
>>> Side topic: state/flow – need to discuss FE/BE state, long-running state (SATOSA is stateless). Shall we have policies around this? Need to describe use cases.
>>>
>>> Use case from Christos and Rainer require extra exchanges during the proxy flow, requiring to preserve state for the whole flow.
>>>
>>> Christos: Cookie deletion is removed with PR #234!
>>>
>>
>> It is now configurable ;)
>>
> <authnrequ_state.png><authnresp_state.png>
