Re: [xwiki-devs] [Proposal] Add api to allow scripts choose with the permission of their author.

On Mar 16, 2010, at 11:08 AM, Caleb James DeLisle wrote: > Denis Gervalle wrote: >> On Tue, Mar 16, 2010 at 03:46, Caleb James DeLisle <calebdelisle(a)lavabit.com >>> wrote: >>> Right now a script which is saved with programming access is allowed to do >>> things which >>> the viewer (who executes it) is not allowed to do. I would like to extend >>> this to scripts which do not >>> have programming access. >>> >>> Use case example: >>> A page where the viewer can submit an email address to be put on a mailing >>> list. The page needs to be able to >>> save the email address to a list but the viewer should not be able to >>> directly edit (or view) the list. >>> >>> I would like to add to xwiki.api.Context: >>> void setScriptUser(String) >>> String getScriptUser() >>> (These names are the best I could think of, suggestions would be great) >>> >>> the input can be either "viewer", "author" or "default" and it stores this >>> in the XWikiContext >>> If the value is set to author, hasAccessLevel will return an access check >>> on the author, not the viewer. >>> >>> When includeForm is called, or the include macro is invoked, the only >>> explicit change is that changes made by >>> the called document will be reset when the include ends. >>> If scrips are set to run with author's permissions: >>> If DocumentA includes documentB, documentB executes with documentB's >>> author's permissions. >>> If DocumentA includes _in context_ documentB, documentB executes with >>> documentA's author's permissions. >>> When include of documentB ends, scriptUser is set back to the value which >>> documentA left it at. >>> >>> I think this will help us achieve the goal of no documents with programming >>> rights in the XE xar file. >>> >>> WDYT? >>> >>> Caleb >>> >>> _______________________________________________ >>> devs mailing list >>> devs(a)xwiki.org >>> http://lists.xwiki.org/mailman/listinfo/devs >>> >> First of all, I am personally against adding anything to the RightService in >> its current state. This is already spaghetti code which already lead to some >> security risks, and trying to improve that partly could be an impossible >> challenge. Moreover, this code is absolutely not optimized, you just have to >> put it under debug logging to understand what I mean. > +1 I read it and I know exactly what you mean, I *think* a rights check could be done > in one query. > > I was only talking about modifying api.Context and api.Api I have no desire to touch > user.impl.xwiki.ANYTHING! > >> Regarding the way you expect the inclusion of documents to function, I am >> not convince that this is the right choice. The behavior of inclusion has >> been broken since Syntax 2.0 has been introduced, and I have always feel >> this to be a serious regression. My principal use case is a document (that >> could have been created by a user) editable by a user, and that store >> objects in itself, and use an inclusion in context for its content. In this >> case, the user may save the document, which should therefore be without any >> special rights, but the code may need to have higher privileges, and still >> require to be included in context for access to the including documents. >> This is the typical Sheet case shown in many sample of XWiki Programming, >> but with programming right requirement. I have used that many times before >> it became broken, and this design is still missing to me. > You bring up an important point which I think is worthy of it's own email. I have thought > it would be nice to allow PR code to extend the api or to add velocity macros > which will run with programming right. > >> I am convince that the rights given to a block of code should be tightly >> linked to the content author > I hereby ammend my proposal to include contentAuthor as a possibility for the set method, I had > forgotten about it. > >> of its containing document, and absolutely not >> based on any author in the context in which it is executed. > Do you mean the viewer? I believe code should never be executed in context of it's viewer > because code may set a trap which saves itself when the viewer has greater privileges than the > code. I propose the set method because I am -1 to changing default behavior. > >> This has been >> broken in Syntax 2.0, and this currently leads to elevation of privilege >> through inclusions. For the same reason, I do not follow Alex on the idea >> that the right should be set in place of a user. This would lead to many >> problem in regards of who and how this could be set, stored and inherited. >> >> I completely agree that the programming right is currently not perfect, but >> in the same time, I do not see the real value you expect to provide. There >> is already a similar mechanism in place, using the content author, opposed >> to the last author of a page. > I want to extend that same mechanism to authors who do not have programming rights, > PR is dangerous and should be used as little as possible and if we need it in the default > xar that is an API flaw IMO. > >> This is what make commenting page possible >> without breaking its programming behavior. Extending this to manage other >> objects in my use case above, is probably a good track to follow. But again, >> this should be part of a global reengineering of the RightService. >> >> If you want to rethink the RightService starting from scratch, I will surely >> participate ! I have already some ideas, but not been able to put them >> properly in a document. Time is always missing, but I hope this to change... > I absolutely do want to rethink the RightService, however I think it is held up by the fact > that components have no access to the HttpServletRequest. Just answering this last point. This is not quite true. Components do have access to the Container component which represents the environment.

However, I don't think it's good that the authentication service relies on it. What do you need exactly from the request? You should expose that need in the Execution Context.

For example imagine that you need some unique id representing the session. If so, then this could be stored in the EC directly or through a more coarsed-grained object. This would allow the authentication service to work in different environments: servlet, portlet, deamon threads, etc.

The other option (maybe even better) is to authenticate the user at the level of the environment, i.e. in Container implementations. And the output of the environment level would be to have a User object put in the Execution Context. I feel this second option is even better than the first since it works without introducing an additional variable in the EC and after all the authentication is related to the environment to some degree.