Re: 2001_05_09 patch against 2.4.4

jmjonesat_private

On Thu, 10 May 2001, Chris Evans wrote:

> 
> On Wed, 9 May 2001, Chris Wright wrote:
> 
> > Latest lsm patch is available.
> >     http://lsm.immunix.org/patches/lsm-2001_05_09-2.4.4.patch.gz
> 
> Found the time for a quick look at "security.h" within this patch.
> Comments follow.
> 

All considered insight is important.

> 1) I didn't see any explict hook for file opening. I see
> file_ops->alloc_security, but that seems to be something else. (also it
> does not allow a security module to return other than EACCES. For
> prevention of covert channels, you might want to return ENOENT even if
> the file exists)
> 
> 2) I see, currently, that syscalls are not hooked in a generic manner.
> >From exceptionally brief scanning of the archives, this seems to be a
> debated point.
> Are there plans to hook syscalls? If not, I can make a very strong
> argument to do so. Let me know if you want to hear it.

> 
> 3) There's a problem brewing with regards lack of central control points
> for logically equivalent operations.
> For example, in file_security_ops, I see separate hooks for mmap, read,
> write, readv, writev. But, logically, mmap(..., PROT_WRITE,
> MAP_SHARED, ...) is equivalent to write().
> Lack of central control may result in a module blocking access to some
> operation, but leave a "backdoor" where the same operation is let through
> by a different syscall sequence to achieve the same effect.
> 
> 
> Cheers
> Chris
> 
> 
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> 

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||  J. MELVIN JONES            jmjonesat_private 
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