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

Al Viro
2021-05-20T06:28:53Z

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.

> + 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?

IOW, why bother with that crap at all, nevermind exporting it?