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Re: subversion-authorization (other than authz)

From: Michel Brabants <michel.brabants_at_euphonynet.be>
Date: 2006-09-19 23:12:56 CEST

Hello,

a little, but important correction.

Op dinsdag 19 september 2006 23:07, schreef Michel Brabants:
> Hello,
>
> I'm nto sure if I'll have a look ath the patch because I wouldn't like the
> maintenance-time it could cost me. Maybe I'll have a look ...
>
> Let's see how I would design it ... :)
>
> Op dinsdag 19 september 2006 20:51, schreef Lieven Govaerts:
> > michel.brabants@euphonynet.be wrote:
> > > Hello,
> > >
> > > I checked on roadmap-site of subversiona nd can't seem to find any plans
> > > to provide a kind of plugin-system to provide additional methods of
> > > authorization . This is a point in which subversion is lacking to my
> > > opinion. I could use apache to direct this, but I don't find this a good
> > > solution. If I would use apache to limit access, those permissions
> > > wouldn't be applied when ssh+svn would be used (which isn't the case).
> > > However, we use trac, which also only shows the content that a user may
> > > view, based on the authz-file. So, using apache for authorization would
> > > allow users to view the content through the trac-browse-feature.
> > > I could synchronize the files manually or using hooks to update the
> > > authz-file, but I'm not sure if that covers everything (have to check) and
> > > a plugin-system of a direct ldap-implentation would be better.
> > >
> > > So, are there any plans to implement ldap-authorization and is there a
> > > planning?
> > >
> > This has been discussed before, but there's no real set of requirements
> > let alone a design of how that will look like. Feel free to step in :)
> >
>
> Maybe an important note: I'm not so familiar with the code of the
> subversion-system.
> Ok, this is a quick try ...
>
> * Requirements:
> It has to define who can access which data in the subversion-system.
>
> * Which are the different types of data in the subversion-system, are there
> dependencies between them and what type of data do they expose?
>
> types of data:
> 1) versionned data -> versionned files, directories and the relationships
> between them.
> 2) subversion-properties that are part of a particular version? For example:
> log-data(?), bug-id, ...
>
> I'll leave the dependencies a little bit open for the moment although it at
> least partly mentionned above.
>
> 1)
> + So, to have full controll, one should have access-control on all data in a
> change-set. Now, let's say that a file A appears in changesets 1,2 and 5. An
> entity John has access to the file in changesets 1 and 5, but not in 2.
> However, the patch for the file A in changeset 2 can be applied properly
> without the changes in changeset 2.
The latter sentence should be: However, the patch for the file A in changeset 5 can be applied properly without the changes in changeset 2.
> What should one do? Maybe another entity
> Jeffrey was adding information to the file 1 in changeset 2 that shouldn't be
> disclosed to the entity John, so that is why John doesn has access to the
> patch for file A in changeset 2. However, this means that the view of how the
> patch for file 1 should look like after changeset 2 is different for John and
> Jeffrey. The "worst" part is, that if there would be a conflict because of
> John uploading a patch after changeset 2, John would have a difficult time
> resolving the problem because he doesn't have access to the changes.
> If you would do this in a "secure" way, one would encrypt each separate part
> according to the persons who have access to the data. Maybe one could write
> this down in a more formal way ... Maybe it helps. Ofcourse, the data could
> appear unencrypter afterwards ... So, if one would apply restrictions on
> already existing changesets ..., one can cause conflicts n the context of the
> view that those restrictions create on the repository. One should be able to
> see the conflicts it creates when the restrictions are applied ...
>
> + Additional logic could be applied by saying that if a complete file/part(?)
> is hidden completely from entity John in revision 7, that that file is also
> hidden from John in revision 2 from then onwards. The file wasn't hidden from
> the entity John in revision 2. Ofcourse, the entity John could already have
> downloaded the file as it existed in revision 2.
>
> 2) Log-data can apply to parts of code, ... With this I mean, that it could
> reveal data concerning data that was hidden from the user. I'll stop here for
> the moment ...
>
> Maybe I went already further than what you meant, but I would like to have
> versionned access-controll. Why? Let's say that I move a file, then the
> restrictions of the "old" version should still be applied to the new one.
> However, one can say that I'm already describing behavour that is not wanted
> by everyone. This is true and I think that it doesn't matter in my above
> explanation when security is applied to parts within changesets. One could
> describe their own behaviour when the above explanation is applied (after
> improvement maybe). Another example maybe. What when I have defined a
> directory as a way of protecting my files and afterwards I move a file ...
> This could actually be a wrong way of applying permissions. There should be a
> permission of not be able to see/delete/... files. A directory is only the
> groupation(?) of files. However, one could maybe define logic-rules that will
> allow the method of "a directory protecting files" still to be secure.
> This seem to be getting a security-implementation. This is actually true I
> think :).
>
> So, to conclude. When a person applies a patch, the repository should call an
> api that shows restricts it to the context of the user. More specifcally, it
> shows him the repository as the user would/should see it and then applies the
> operation of the user. Ofcourse, there could be conflicts with views (of the
> repository) of other users ...
> Maybe there already exist theories about security for versionned data ... it
> is actually not "more" I think than relationships between data which cause
> the security-data to be applied to other data also.
>
> Ok, I know that the authorization-information is not versionned now, but maybe
> it would be interesting to version it like mentionned above.
> ----------------------
> Ofcourse the api ...
>
> + getRepositoryView(entity) for getting the view on the repoitory. I don't
> care if the security-information (what he may see) is available in a
> text-file, in a database, an ldap-server of in which format it could exist.
> If groups are also used, the groups that appear in the repository could be
> fetched from an ldap-server. Ofcourse, there is information-exposure to the
> ldap-server, but ok I'll leave it at this for now :).
>
> getRepositoryView returns a repository-object which allows to browse the
> repository as the user sees it. The repository-object contains files,
> directories, properties and all the other (types of) data available in the
> repository. One could implement the object that returns the view as a
> different server (like it is maybe now), so that one could easily build a
> (fuse-)filesystem or so on top of it ...
>
> The object that returns the repository could implement a function
> + getRepositoryView(DataRestrictions/DataAllowonce) (or an object that returns
> this information)
> The object that return the information could be a textreader for a specific
> format, a class that reads the information from a database or an ldap-server.
> These classes would define what type of information they need to define the
> datarestrictions/allowances.
> Explicitly allowing data could maybe usefull for avoiding mistakes ... Why
> should denying it later overwrite allowing it earlier?
>
> I hope that this information was usefull. Greetings,
>
> Michel
>
> > Some time ago there was a patch on the dev list which might or might not
> > do what you want:
> > http://svn.haxx.se/dev/archive-2006-07/0107.shtml
> >
> > Lieven.
> >
>
>
>

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Received on Tue Sep 19 23:13:53 2006

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