[LTP] [RFC PATCH] LTP Wrapper for Syzkaller reproducers

[Dmitry Vyukov]

On Thu, Oct 10, 2019 at 11:30 AM Cyril Hrubis <chrubis@suse.cz> wrote:
>
> Hi!
> > > > > Indeed, it's removed recursively by the test library.
> > > >
> > > > :popcorn:
> > > >
> > > > It took me several years to figure out how to more or less reliably
> > > > remove dirs after the fuzzer ;)
> > > > (no, unlink won't do ;))
> > >
> > > I guess that there are things such as immutable file attributes that has
> > > to be cleared and many more. Do you have piece of code somewhere that we
> > > can look into to spare us from reinventing the wheel?
> >
> > Here is what we have:
> > https://github.com/google/syzkaller/blob/c4b9981b5f5b70dc03eb3f76c618398510101a1d/executor/common_linux.h#L2358-L2461
> > Maybe it can be simplified, but that's what we ended up with after
> > some organic evolution. At least the comments may give some hints as
> > to what may go wrong.
>
> Thanks a lot!
>
> Also I see that you are using namespaces, and much more, to sandbox the
> fuzzer, I was wondering if we should do that, at least separate user and
> pid namespace sounds like a good idea to me.

I don't know how far you want to go. This sandboxing definitely helps
us to isolate processes and make tests more repeatable by avoiding
interference (I don't know if LTP, say, runs tests in parallel).
mount namespaces are useful to later drop all of test mounts at once,
this would solve a significant part of the remote_dir logic. If the
temp dir is on tmpfs in the mount namespace as well, then it will be
automatically dropped altogether with all contents.