[Mono-devel-list] RE: Code Access Security

[Benjamin Wootton]

Thanks for reply.  I'm now actively working on this, so dare say I will have
lots of questions!

> > I've been implementing CodeAccessPermission.Demand.
> 
> Without some runtime support this won't be easy to do, fix or test - I
> know
> as a tried a little ;)

I understand this all pretty well now, at least with imperative demands.  I
think I'm right in believing that declarative is harder.

Thanks for the explanation of policies etc.  Presumably CAS builds up the
policy objects based on the information in the security config files:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/htm
l/cpconsecurityconfigurationfiles.asp

I thought about starting to write a caspol to manipulate these policy files
- I'm going some dummy data in the Policy classes to proceed.  Might as well
build this in C#.  Also is there anything I should consider as to how the
runtime should load these files, where they should be stored etc?  There are
also going to be interesting mappings between some MS permission concepts
and those in Unix, presumably.

Finally, I also need to get a specification together of what exactly is
required for CAS, and identify a point where I have the basic thing - and
what constitutes the extensions.  I'd appreciate if I could hack this out
with other members on the list...

Just wanted to check I'm on the right path.

Thanks
Ben


 

> E.g. (again incomplete)
> 
> - The runtime is asked to load an assembly from
> "http://www.go-mono.com/mono.dll";
> - The runtime add an URL evidence for "http://www.go-mono.com/mono.dll" to
> the assembly;
> - The URL is then used to determine a SecurityZone (using
> Zone.CreateFromURL
> and re-using IE settings) which results in Internet;
> - The PermissionSet for Internet can then be applied.
> - If a method ask for a FileIOPermission then "CAS" will check if the
> Internet permission set and refuse the operation.
> 
> However if the mono.dll had a strongname (e.g. from Ximian) a Code Groups
> could give the assembly a different set of permissions (like FullTrust).
> 
> > For instance, we can define code groups and membership conditions in MS
> > at the various levels, but how do the class libraries come into it?
> 
> The "CAS engine" resides in the runtime for both performance and security
> (isolation). But to make CAS extendable most of objects it works with are
> implemented in managed code (in the class library).
> 
> > Do they just reflect the policy as granted by the local system, so that
> > we can work with this programmatically?  If this is the case, should
> there
> > be a PermissionSet in there somewhere representing the final grant set?
> 
> That's the job of CAS to resolve it all ;) with the help from the class
> library.
> However it can be "a" final grant set - as every assembly can have
> different
> trust level inside an application domain
> 
> > Any insights you can give into this would be very much appreciated!
> 
> Have a look at bugzilla #52693
> (http://bugzilla.ximian.com/show_bug.cgi?id=52693). This may be easier to
> do
> (but still a big step) and make it more easier to complete CAS afterward.
> 
> BTW please keep your bugzilla entry
> (http://bugzilla.ximian.com/show_bug.cgi?id=52606) updated with your work
> (I
> bookmarked it) or keep a blog about your work. It's the best way for
> everyone (not just me) to see what's happening with CAS.
> 
> Cya
> 
> Sebastien Pouliot
> Security Architect, Motus Technologies, http://www.motus.com
> work: spouliot at motus.com
> home: spouliot at videotron.ca
> blog: http://pages.infinit.net/ctech/poupou.html
> 
> -----Original Message-----
> From: Ben [mailto:benjaminwootton at hotpop.com]
> Sent: 12 janvier 2004 03:24
> To: spouliot at videotron.ca
> Subject: RE: Code Access Security
> 
> 
> Sorry to contact you again.  I've been implementing
> CodeAccessPermission.Demand.  I've been trying to work out this evening
> how
> System.Security.Policy, Evidence and Code Groups fit together.  I
> understand
> them in isolation, but I'm not sure how they fit into the rest of the
> framework.
> 
> For instance, we can define code groups and membership conditions in MS at
> the various levels, but how do the class libraries come into it?  Do they
> just reflect the policy as granted by the local system, so that we can
> work
> with this programmatically?  If this is the case, should there be a
> PermissionSet in there somewhere representing the final grant set?
> 
> Any insights you can give into this would be very much appreciated!
> 
> Thanks
> Ben
> 
> 
> 
> 
> 
> 
> 
> From: Ben [mailto:benjaminwootton at hotpop.com]
> Sent: Saturday, January 10, 2004 11:47 PM
> To: 'spouliot at videotron.ca'
> Subject: Code Access Security
> 
> You posted to mono-devel last week about code access security.  I tried to
> reply, but I'm not sure if it got through or not.
> 
> I'm currently implementing parts of it.  I wanted to check we were not
> duplicating any work, and also to see if you had any insights into how you
> think this should be done.
> 
> I'm currently making sure that permissions are correctly represented in
> the
> assembly metadata.  At the moment, Security permissions are just shown as
> normal custom attributes.
> 
> Ben