Re: [RFC PATCH ghak9 0/3] audit: Record the path of FDs passed to *at(2) syscalls

Steve Grubb
2018-07-25T13:11:38Z

On Wednesday, July 25, 2018 9:02:50 AM EDT Ondrej Mosnacek wrote:
> On Wed, Jul 25, 2018 at 2:48 PM Steve Grubb <sgrubb@redhat.com> wrote:
> > On Wednesday, July 25, 2018 3:44:07 AM EDT Ondrej Mosnacek wrote:
> > > On Wed, Jul 25, 2018 at 3:11 AM Steve Grubb <sgrubb@redhat.com> wrote:
> > > > On Tuesday, July 24, 2018 6:15:54 PM EDT Paul Moore wrote:
> > > > > On Tue, Jul 24, 2018 at 10:12 AM Ondrej Mosnacek
> > > > > <omosnace@redhat.com>
> > > > >
> > > > > > Beyond that, there is really no information in the records that
> > > > > > would
> > > > > > allow reconstructing which PARENT path belongs to which
> > > > > > CREATE/DELETE
> > > > > > path... (Intuitively you can guess that src will come before dst,
> > > > > > but
> > > > > > that is not very reliable.) I think a "parent inode" field in the
> > > > > > PATH
> > > > > > records could fix this, but maybe there is a better solution...
> > > > >
> > > > > I have my suspicions, but I would be curious to hear from Steve how
> > > > > the reconstruction is typically handled.
> > > >
> > > > For any *at function when the dirfd is not AT_FDCWD, it goes badly.
> > > > If
> > > > its a old style syscall without the dirfd, then if the first
> > > > character
> > > > is '/' use that. Otherwise concatonate cwd and path and pass it to
> > > > realpath to sort out.
> > >
> > > In that case it seems the best fix for openat() et al. would be to
> > > somehow always force outputting the full path when dirfd != AT_FDCWD.
> > > Hopefully that won't require too much hacking around...
> >
> > What is asked for is the full path that dirfd was opened with. I can take
> > care of everything else.
>
> But where/how should that path be logged? In case of renameat(), for
> example, we have 6 (!) path components:
> <src_dir>/<src_parent>/<src_child> and <dst_dir>/<dst_parent>/<dst_child>
>
> (I am assuming the child paths always represent just the last path
> component based on the observed inodes of the parent/child records.)
>
> Current record format can distinguish between PARENT and child
> (DELETE/CREATE), but there is no nametype for the dirfd path. That's
> why I am leaning towards just logging the full "<*_dir>/<*_parent>"
> path in the PARENT record. Or do you prefer that we add a new nametype
> for the dirfd path?

You could make a new nametype so that we can make sense of it. But do you
have all of the required information for a PATH record? I thought that you
were making a new record type since you have abbreviated information.

-Steve