Re: Common header for security blobs

From: Greg KH (gregat_private)
Date: Thu Sep 06 2001 - 13:32:00 PDT

  • Next message: Greg KH: "Re: quotactl hook"

    On Thu, Sep 06, 2001 at 04:13:30PM -0400, Stephen Smalley wrote:
    > 
    > 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. 
    
    That sounds like a nice way to stack your modules together _if_ you want
    to do that.
    
    If not, the overhead of having another void * indirection, and a search
    on a list of 1 member (another indirection), would not be nice for those
    people concerned with speed issues.
    
    It might be a nice thing to do for round 2 if people think it's
    worthwhile.  I think we should leave it alone for now and polish up what
    we currently have.
    
    thanks,
    
    greg k-h
    
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