[PATCH RESEND v2 15/18] fuse: Add support for pid namespaces

[Seth Forshee]

On Wed, Mar 09, 2016 at 11:53:17AM +0100, Miklos Szeredi wrote:
> On Mon, Jan 04, 2016 at 12:03:54PM -0600, Seth Forshee wrote:
> > If the userspace process servicing fuse requests is running in
> > a pid namespace then pids passed via the fuse fd need to be
> > translated relative to that namespace. Capture the pid namespace
> > in use when the filesystem is mounted and use this for pid
> > translation.
> > 
> > Since no use case currently exists for changing namespaces all
> > translations are done relative to the pid namespace in use when
> > /dev/fuse is opened.
> 
> The above doesn't match what the patch does.
> 
>  - FUSE captures namespace at mount time
> 
>  - CUSE captures namespace at /dev/cuse open

Possibly an earlier version of the patch worked that way and I forgot to
update the description after it change. Anyway, I'll fix it.

> >  Mounting or /dev/fuse IO from another
> > namespace will return errors.
> > 
> > Requests from processes whose pid cannot be translated into the
> > target namespace are not permitted, except for requests
> > allocated via fuse_get_req_nofail_nopages. For no-fail requests
> > in.h.pid will be 0 if the pid translation fails.
> > 
> > File locking changes based on previous work done by Eric
> > Biederman.
> > 
> > Signed-off-by: Seth Forshee <seth.forshee at canonical.com>
> > Signed-off-by: Miklos Szeredi <mszeredi at suse.cz>
> 
> Not sure how my SOB got on this patch, use this instead:
> 
> Acked-by: Miklos Szeredi <mszeredi at redhat.com>

My memory is that you had sent a patch as a proposed alternative to one
of my earlier patches, and I squashed the two together and added your
SOB at that point. I'll change it.

Thanks,
Seth