Re: Determing the difference between path_walk and chdir ?

From: David Wagner (dawat_private)
Date: Tue Sep 25 2001 - 17:24:46 PDT

  • Next message: richard offer: "Re: Determing the difference between path_walk and chdir ?"

    richard offer  wrote:
    >path_walk is "transient", it doesn't affect any subsequent decisions. chdir
    >affects all subsequent (relative) file accesses.
    
    You mean, you're keeping shadow state about what directory the application
    is in?  Isn't this really dangerous?  If your shadow state ever becomes
    inconsistent with the kernel's state, your policy decision will be
    incorrect, and you can end up with serious security holes.
    
    From my point of view, one of the great advantages of LSM is that it gives
    us interfaces into the kernel that avoid the need to try to track what
    the kernel is doing, emulate its idiosyncracies, and keep shadow state.
    What is it you really want to do, and how can we improve LSM to enable
    what you want to do in a safer way?
    
    >I know, and if I could think cleverer I would, the real problem is the
    >overloading of the flags given to permission()
    
    Interesting observation.  Some of these can be resolved unambiguously
    (e.g., MAY_EXEC on a directory vs. on a file), but I'm not sure that all
    can, and I can imagine that some others might be more important in some
    cases (e.g., create vs. delete).  Good point.
    
    _______________________________________________
    linux-security-module mailing list
    linux-security-moduleat_private
    http://mail.wirex.com/mailman/listinfo/linux-security-module
    



    This archive was generated by hypermail 2b30 : Tue Sep 25 2001 - 17:41:59 PDT