Re: Re: [PATCH v7 11/12] vduse: Introduce VDUSE - vDPA Device in Userspace

From: Yongji Xie <xieyongji@bytedance.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
	"Jason Wang" <jasowang@redhat.com>,
	"Stefan Hajnoczi" <stefanha@redhat.com>,
	"Stefano Garzarella" <sgarzare@redhat.com>,
	"Parav Pandit" <parav@nvidia.com>,
	"Christoph Hellwig" <hch@infradead.org>,
	"Christian Brauner" <christian.brauner@canonical.com>,
	"Randy Dunlap" <rdunlap@infradead.org>,
	"Matthew Wilcox" <willy@infradead.org>,
	"Jens Axboe" <axboe@kernel.dk>,
	bcrl@kvack.org, "Jonathan Corbet" <corbet@lwn.net>,
	"Mika Penttilä" <mika.penttila@nextfour.com>,
	"Dan Carpenter" <dan.carpenter@oracle.com>,
	joro@8bytes.org,
	virtualization <virtualization@lists.linux-foundation.org>,
	netdev@vger.kernel.org, kvm <kvm@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org, iommu@lists.linux-foundation.org,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: Re: [PATCH v7 11/12] vduse: Introduce VDUSE - vDPA Device in Userspace
Date: Thu, 20 May 2021 15:03:01 +0800	[thread overview]
Message-ID: <CACycT3vTvdJN4qnp=O8E5fxR15evMexzsK+V_uFT0LZkRSCitw@mail.gmail.com> (raw)
In-Reply-To: <YKYBle/F8aOgHO9p@zeniv-ca.linux.org.uk>

On Thu, May 20, 2021 at 2:28 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> On Mon, May 17, 2021 at 05:55:12PM +0800, Xie Yongji wrote:
>
> > +     case VDUSE_IOTLB_GET_FD: {
> > +             struct vduse_iotlb_entry entry;
> > +             struct vhost_iotlb_map *map;
> > +             struct vdpa_map_file *map_file;
> > +             struct vduse_iova_domain *domain = dev->domain;
> > +             struct file *f = NULL;
> > +
> > +             ret = -EFAULT;
> > +             if (copy_from_user(&entry, argp, sizeof(entry)))
> > +                     break;
>
>                         return -EFAULT;
> surely?
> > +
> > +             ret = -EINVAL;
> > +             if (entry.start > entry.last)
> > +                     break;
>
> ... and similar here, etc.
>

OK.

> > +             spin_lock(&domain->iotlb_lock);
> > +             map = vhost_iotlb_itree_first(domain->iotlb,
> > +                                           entry.start, entry.last);
> > +             if (map) {
> > +                     map_file = (struct vdpa_map_file *)map->opaque;
> > +                     f = get_file(map_file->file);
> > +                     entry.offset = map_file->offset;
> > +                     entry.start = map->start;
> > +                     entry.last = map->last;
> > +                     entry.perm = map->perm;
> > +             }
> > +             spin_unlock(&domain->iotlb_lock);
> > +             ret = -EINVAL;
> > +             if (!f)
> > +                     break;
> > +
> > +             ret = -EFAULT;
> > +             if (copy_to_user(argp, &entry, sizeof(entry))) {
> > +                     fput(f);
> > +                     break;
> > +             }
> > +             ret = receive_fd(f, perm_to_file_flags(entry.perm));
> > +             fput(f);
> > +             break;
>
> IDGI.  The main difference between receive_fd() and plain old
> get_unused_fd_flags() + fd_install() is __receive_sock() call.
> Which does nothing whatsoever in case of non-sockets.  Can you
> get a socket here?
>

Actually what I want here is the security_file_receive() hook in receive_fd().

Thanks,
Yongji