Descriptor table is a shared resource; two fget() on the same descriptor
may return different struct file references.  get_tap_ptr_ring() is
called after we'd found (and pinned) the socket we'll be using and it
tries to find the private tun/tap data structures associated with it.
Redoing the lookup by the same file descriptor we'd used to get the
socket is racy - we need to same struct file.

Thanks to Jason for spotting a braino in the original variant of patch -
I'd missed the use of fd == -1 for disabling backend, and in that case
we can end up with sock == NULL and sock != oldsock.

Cc: stable@kernel.org
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

In patch [1], tun_msg_ctl was added to allow pass batched xdp buffers to
tun_sendmsg. Although we donot use msg_controllen in this path, we should
check msg_controllen to make sure the caller pass a valid msg_ctl.

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fe8dd45bb7556246c6b76277b1ba4296c91c2505

Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Suggested-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Harold Huang <baymaxhuang@gmail.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20220303022441.383865-1-baymaxhuang@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

If the sendmsg() call in vhost_tx_batch() fails, both the 'batched_xdp'
and 'done_idx' indexes are left unchanged. If such failure happens
when batched_xdp == VHOST_NET_BATCH, the next call to
vhost_net_build_xdp() will access and write memory outside the xdp
buffers area.

Since sendmsg() can only error with EBADFD, this change addresses the
issue explicitly freeing the XDP buffers batch on error.

Fixes: 0a0be13b8fe2 ("vhost_net: batch submitting XDP buffers to underlayer sockets")
Suggested-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Both SKB_FRAG_PAGE_ORDER are defined to the same value in
net/core/sock.c and drivers/vhost/net.c.

Move the SKB_FRAG_PAGE_ORDER definition to net/core/sock.h,
as both net/core/sock.c and drivers/vhost/net.c include it,
and it seems a reasonable file to put the macro.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Make use of the xdp_{init,prepare}_buff() helpers instead of
an open-coded version.

Also, the field xdp->rxq was never set, so pass NULL to xdp_init_buff()
to clear it.

Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Currently the driver doesn't drop a packet which can't be sent by tun
(e.g bad packet). In this case, the driver will always process the
same packet lead to the tx queue stuck.

To fix this issue:
1. in the case of persistent failure (e.g bad packet), the driver
   can skip this descriptor by ignoring the error.
2. in the case of transient failure (e.g -ENOBUFS, -EAGAIN and -ENOMEM),
   the driver schedules the worker to try again.

Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://lore.kernel.org/r/1610685980-38608-1-git-send-email-wangyunjian@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Replace direct assignments with skb_zcopy_init() for zerocopy
cases where a new skb is initialized, without changing the
reference counts.

Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add an optional skb parameter to the zerocopy callback parameter,
which is passed down from skb_zcopy_clear().  This gives access
to the original skb, which is needed for upcoming RX zero-copy
error handling.

Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Currently the vhost_zerocopy_callback() maybe be called to decrease
the refcount when sendmsg fails in tun. The error handling in vhost
handle_tx_zerocopy() will try to decrease the same refcount again.
This is wrong. To fix this issue, we only call vhost_net_ubuf_put()
when vq->heads[nvq->desc].len == VHOST_DMA_IN_PROGRESS.

Fixes: bab632d69ee4 ("vhost: vhost TX zero-copy support")
Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/1609207308-20544-1-git-send-email-wangyunjian@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Pull virtio updates from Michael Tsirkin:

 - IRQ bypass support for vdpa and IFC

 - MLX5 vdpa driver

 - Endianness fixes for virtio drivers

 - Misc other fixes

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (71 commits)
  vdpa/mlx5: fix up endian-ness for mtu
  vdpa: Fix pointer math bug in vdpasim_get_config()
  vdpa/mlx5: Fix pointer math in mlx5_vdpa_get_config()
  vdpa/mlx5: fix memory allocation failure checks
  vdpa/mlx5: Fix uninitialised variable in core/mr.c
  vdpa_sim: init iommu lock
  virtio_config: fix up warnings on parisc
  vdpa/mlx5: Add VDPA driver for supported mlx5 devices
  vdpa/mlx5: Add shared memory registration code
  vdpa/mlx5: Add support library for mlx5 VDPA implementation
  vdpa/mlx5: Add hardware descriptive header file
  vdpa: Modify get_vq_state() to return error code
  net/vdpa: Use struct for set/get vq state
  vdpa: remove hard coded virtq num
  vdpasim: support batch updating
  vhost-vdpa: support IOTLB batching hints
  vhost-vdpa: support get/set backend features
  vhost: generialize backend features setting/getting
  vhost-vdpa: refine ioctl pre-processing
  vDPA: dont change vq irq after DRIVER_OK
  ...