Re: Possible system call interface for LSM

From: jmjonesat_private
Date: Fri Aug 10 2001 - 18:24:14 PDT

  • Next message: David Wagner: "Re: Possible system call interface for LSM"

    On Fri, 10 Aug 2001, Crispin Cowan wrote:
    
    > David Wagner wrote:
    > 
    > > Greg KH  wrote:
    > > >Ah, but Stephans program should first validate that the kernel is
    > > >running SELinux by some other method than the syscall [...]
    > >
    > > Are there race conditions here?  What if someone does a
    > > 'rmmod selinux; insmod subdomain' between the time when
    > > you check for the presence of SELinux and use the syscall?
    > 
    > Isn't that isomorphic to the problem of "what if the bad guy got control
    > of the machine before my module loaded?"  To me, anyone who can do
    > "rmmod" is either a trusted administrator, or has already broken
    > security so hopelessly that it's not worth arguing about.
    
    Well, there's the issue of properly executing applications when the module
    changes (minimally.)  RMMOD/INSMOD arguably have to be trusted, but a
    sleeper application CAN bridge the rmmod/insmod.  That's why I keep
    insisting the module has to check every call... but, (again), it is up to
    the MODULE, not the interface or kernel, to check this, imho. 
    
    > 
    > Crispin
    > 
    > --
    > Crispin Cowan, Ph.D.
    > Chief Scientist, WireX Communications, Inc. http://wirex.com
    > Security Hardened Linux Distribution:       http://immunix.org
    > Available for purchase: http://wirex.com/Products/Immunix/purchase.html
    
    J. Melvin Jones
    
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