Re: A Comment from User Space

From: Stephen Smalley (sdsat_private)
Date: Tue Apr 24 2001 - 12:10:23 PDT

  • Next message: Tim Hollebeek: "RE: A Comment from User Space"

    On 24 Apr 2001, David Wagner wrote:
    
    > Well, using a /proc interface takes at worst only two syscalls:
    >   fd = open("/proc/subdomain", O_RDWR);
    >   write(fd, "change_hat foo_perm ...", ...);
    > If you cache the fd, it takes only one syscall.  So, while I cannot
    > guarantee that it will be fast enough for your purposes, I would expect
    > that it most likely is about as good as a syscall.  Without measurements
    > to the contrary, I would expect a difficult time getting acceptance
    > from linux-kernel residents (although that's just a guess).
    
    Why is such an approach preferable to reserving an actual
    system call for use by security modules?  Since Linus is 
    willing to consider accepting security hooks into the kernel,
    it doesn't seem unreasonable to request that a system call
    be reserved for such use.  If implementing system calls
    via pseudo file systems is the way to go, then why
    aren't the kernel developers migrating most of the 
    existing system calls to such an approach?  I would suggest
    that we make the attempt to gain acceptance for a reserved
    call, and fall back to using pseudo file systems only if our
    request is rejected.
    
    --
    Stephen D. Smalley, NAI Labs
    ssmalleyat_private
    
    
    
    
    
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