On Mon, 2 Jul 2007, Andy Isaacson wrote:
> On Sat, Jun 30, 2007 at 12:03:07PM -0700, Davide Libenzi wrote:
> > I think the focus should be to find a case where under the currently
> > implemented policy for MAP_NOZERO, MAP_NOZERO represent a loss of security
> > WRT no MAP_NOZERO. I have not been able to find one yet, although Andy
> > found a potential one in the setuid+exec/ptrace race (fixed by a patch
> > that should IMO go in in any case).
>
> BTW, the ptrace variant of this issue is not a problem -- PTRACE_ATTACH
> running as newuid gets EPERM when trying to attach at /* here */ below.
>
> setuid(newuid);
> /* here */
> exec(...);
> exit(1);
>
> sys_setuid sets current->mm->dumpable = suid_dumpable, so unless the
> admin asked for it, there is no risk WRT PTRACE_ATTACH. However, this
> risk vector does need to be considered when implementing MAP_NOZERO.
Yes, I missed that. Ptrace is fine there. The 3 lines patch is still
needed for MAP_NOZERO though.
- Davide
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