Re: [RFC][PATCH] rbind across namespaces

[Jamie Lokier <jamie@shareable.org>]

Mike Waychison wrote:
> >   1. Deny access to /proc/NNN/fd/, /proc/NNN/cwd, /proc/NNN/root
> >      if task NNN cannot be ptraced.
> >
> >   3. Allow entry to /proc/NNN/fd/, /proc/NNN/cwd, /proc/NNN/root
> >      if ptrace is allowed; the namespace being irrelevant.
> >
> >   3. Use _exactly_ the same condition as for ptracing,
> >      i.e. MAY_PTRACE in fs/proc/base.c.  Ensure that condition is
> >      consistent with the tests in kernel/ptrace.c, possibly putting
> >      the condition in a common header file to keep it consistent in
> >      future.
> >
> >   4. If further restrictions are desired, to make namespaces more
> >      strict, those should be implemented by further restrictions on
> >      which tasks are allowed to ptrace other tasks.
> >
> 
> Indeed.  A combination of MAY_PTRACE ||ed with a check against current 
> sounds reasonable to me.

Note that MAY_PTRACE already includes a check against current.

-- Jamie