Re: Common header for security blobs

From: Stephen Smalley (sdsat_private)
Date: Thu Sep 06 2001 - 13:13:30 PDT

  • Next message: Greg KH: "Re: Common header for security blobs"

    On Thu, 6 Sep 2001, Chris Wright wrote:
    
    > something needs to coallate the modules' decisions and generate an
    > aggreagrate result.
    
    This is true, but the lack of a common header makes a lot more work for
    the multiplexor module.  As I said earlier, without a common header,
    the multiplexor module must save the original security field on entry to
    the hook, and then set the field to point to each module's object before
    calling each module's hook.  Same thing in reverse on allocation of the 
    objects.  The problem is that the modules directly dereference the kernel
    object's security field to set and access it, so they are all looking in
    the same place.
    
    If we have a common header, then each module can simply be written to
    search the list in the header for its own object, identified by the module
    id.  Likewise, each module can be written to insert a new blob into the
    list when alloc_security is called.  This simplifies the multiplexor
    module to merely calling the submodules in sequence on the kernel objects,
    without needing to tweak the security field at all. 
    
    > and if we add the magic number and list, we'd need to initialize them in a
    > generic fashion before calling the module's alloc_security() wouldn't we?
    
    No.  That would be up to the individual modules.
    
    --
    Stephen D. Smalley, NAI Labs
    ssmalleyat_private
    
    
    
    
    
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