linux-kernel - Re: Re: [PATCH v7 11/12] vduse: Introduce VDUSE

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Date:   Thu, 20 May 2021 15:03:01 +0800
From:   Yongji Xie <xieyongji@...edance.com>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Stefano Garzarella <sgarzare@...hat.com>,
        Parav Pandit <parav@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        Christian Brauner <christian.brauner@...onical.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Matthew Wilcox <willy@...radead.org>,
        Jens Axboe <axboe@...nel.dk>, bcrl@...ck.org,
        Jonathan Corbet <corbet@....net>,
        Mika Penttilä <mika.penttila@...tfour.com>,
        Dan Carpenter <dan.carpenter@...cle.com>, joro@...tes.org,
        virtualization <virtualization@...ts.linux-foundation.org>,
        netdev@...r.kernel.org, kvm <kvm@...r.kernel.org>,
        linux-fsdevel@...r.kernel.org, iommu@...ts.linux-foundation.org,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: Re: [PATCH v7 11/12] vduse: Introduce VDUSE - vDPA Device in Userspace

On Thu, May 20, 2021 at 2:28 PM Al Viro <viro@...iv.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