Linux-kernel mailing list archive 1998-31,: Re: Stack Smashing and no-exec

# Re: Stack Smashing and no-exec

Kragen (kragen@pobox.com)
Fri, 7 Aug 1998 23:18:12 -0400 (EDT)

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On Fri, 7 Aug 1998, Jon M. Taylor wrote:
> On Fri, 7 Aug 1998, Kragen wrote:
> > On Fri, 7 Aug 1998, Jon M. Taylor wrote:
> > > As long as Linux is a traditional monolithic Unix-like kernel, I
> > > think this is a reasonable attitude to have. Linus is correct. The suid
> > > root programs should be fixed. If that task is difficult, use bounds
> > > checking or whatever you need to be able to fix the problems.
> >
> > I think some kind of small-interface solution like bounds-checking
> > compilers should help considerably -- but, of course, it's not a
> > panacea.
>
> Right. The point is that the primary responsibility must lie with
> the suid root code. The kernel can help catch these bugs, as can various
> other tools like the compiler, but ultimately the code needs to be fixed.

No, that wasn't what I meant. If you have a compiler that does
bounds-checking in a reliable fashion, you may indeed be able to avoid
adding features to the code to make sure it doesn't buffer-overflow.
In fact, you might be better off that way.

What I meant was that there are (many!) other security bugs that are
not the result of wild pointers, and so you can't rely on your compiler
to catch them.

> > Lots
> > of things are setuid root so they can bind a reserved port, for
> > example. I'll be a lot happier when I can run named as a normal user!
>
> Would this be done, or would you have a user that has the
> additional priv of being able to bind to that specific port? That is,
> would capabilities be bound to a specific user like group membership is
> now? Or would capabilities be bound to a group instead?

I think capabilities are per-process, not per-group or per-user. Is
there a Linux-capabilities FAQ, anyone?

> Also, how would
> these capabilities be defined? Would there be categories and/or any sort
> of hierarchy to subcategorize the set of all possible capabilities, or
> would it just be one long list of stuff, each capability standing alone?

It's a long list of stuff (less than 32 at the moment, I believe) that
mostly has to do with things only root could do in the past.

Kragen

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