[RFC,net-next,v5,01/14] af_vsock: generalize vsock_dgram_recvmsg() to all transports

Message ID 20230413-b4-vsock-dgram-v5-1-581bd37fdb26@bytedance.com
State New
Headers
Series virtio/vsock: support datagrams |

Commit Message

Bobby Eshleman July 19, 2023, 12:50 a.m. UTC
  This commit drops the transport->dgram_dequeue callback and makes
vsock_dgram_recvmsg() generic to all transports.

To make this possible, two transport-level changes are introduced:
- implementation of the ->dgram_addr_init() callback to initialize
  the sockaddr_vm structure with data from incoming socket buffers.
- transport implementations set the skb->data pointer to the beginning
  of the payload prior to adding the skb to the socket's receive queue.
  That is, they must use skb_pull() before enqueuing. This is an
  agreement between the transport and the socket layer that skb->data
  always points to the beginning of the payload (and not, for example,
  the packet header).

Signed-off-by: Bobby Eshleman <bobby.eshleman@bytedance.com>
---
 drivers/vhost/vsock.c                   |  1 -
 include/linux/virtio_vsock.h            |  5 ---
 include/net/af_vsock.h                  |  3 +-
 net/vmw_vsock/af_vsock.c                | 40 ++++++++++++++++++++++-
 net/vmw_vsock/hyperv_transport.c        |  7 ----
 net/vmw_vsock/virtio_transport.c        |  1 -
 net/vmw_vsock/virtio_transport_common.c |  9 -----
 net/vmw_vsock/vmci_transport.c          | 58 ++++++---------------------------
 net/vmw_vsock/vsock_loopback.c          |  1 -
 9 files changed, 50 insertions(+), 75 deletions(-)
  

Comments

Arseniy Krasnov July 24, 2023, 6:11 p.m. UTC | #1
On 19.07.2023 03:50, Bobby Eshleman wrote:
> This commit drops the transport->dgram_dequeue callback and makes
> vsock_dgram_recvmsg() generic to all transports.
> 
> To make this possible, two transport-level changes are introduced:
> - implementation of the ->dgram_addr_init() callback to initialize
>   the sockaddr_vm structure with data from incoming socket buffers.
> - transport implementations set the skb->data pointer to the beginning
>   of the payload prior to adding the skb to the socket's receive queue.
>   That is, they must use skb_pull() before enqueuing. This is an
>   agreement between the transport and the socket layer that skb->data
>   always points to the beginning of the payload (and not, for example,
>   the packet header).
> 
> Signed-off-by: Bobby Eshleman <bobby.eshleman@bytedance.com>
> ---
>  drivers/vhost/vsock.c                   |  1 -
>  include/linux/virtio_vsock.h            |  5 ---
>  include/net/af_vsock.h                  |  3 +-
>  net/vmw_vsock/af_vsock.c                | 40 ++++++++++++++++++++++-
>  net/vmw_vsock/hyperv_transport.c        |  7 ----
>  net/vmw_vsock/virtio_transport.c        |  1 -
>  net/vmw_vsock/virtio_transport_common.c |  9 -----
>  net/vmw_vsock/vmci_transport.c          | 58 ++++++---------------------------
>  net/vmw_vsock/vsock_loopback.c          |  1 -
>  9 files changed, 50 insertions(+), 75 deletions(-)
> 
> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> index 6578db78f0ae..ae8891598a48 100644
> --- a/drivers/vhost/vsock.c
> +++ b/drivers/vhost/vsock.c
> @@ -410,7 +410,6 @@ static struct virtio_transport vhost_transport = {
>  		.cancel_pkt               = vhost_transport_cancel_pkt,
>  
>  		.dgram_enqueue            = virtio_transport_dgram_enqueue,
> -		.dgram_dequeue            = virtio_transport_dgram_dequeue,
>  		.dgram_bind               = virtio_transport_dgram_bind,
>  		.dgram_allow              = virtio_transport_dgram_allow,
>  
> diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
> index c58453699ee9..18cbe8d37fca 100644
> --- a/include/linux/virtio_vsock.h
> +++ b/include/linux/virtio_vsock.h
> @@ -167,11 +167,6 @@ virtio_transport_stream_dequeue(struct vsock_sock *vsk,
>  				size_t len,
>  				int type);
>  int
> -virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
> -			       struct msghdr *msg,
> -			       size_t len, int flags);
> -
> -int
>  virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
>  				   struct msghdr *msg,
>  				   size_t len);
> diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
> index 0e7504a42925..305d57502e89 100644
> --- a/include/net/af_vsock.h
> +++ b/include/net/af_vsock.h
> @@ -120,11 +120,10 @@ struct vsock_transport {
>  
>  	/* DGRAM. */
>  	int (*dgram_bind)(struct vsock_sock *, struct sockaddr_vm *);
> -	int (*dgram_dequeue)(struct vsock_sock *vsk, struct msghdr *msg,
> -			     size_t len, int flags);
>  	int (*dgram_enqueue)(struct vsock_sock *, struct sockaddr_vm *,
>  			     struct msghdr *, size_t len);
>  	bool (*dgram_allow)(u32 cid, u32 port);
> +	void (*dgram_addr_init)(struct sk_buff *skb, struct sockaddr_vm *addr);
>  
>  	/* STREAM. */
>  	/* TODO: stream_bind() */
> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> index deb72a8c44a7..ad71e084bf2f 100644
> --- a/net/vmw_vsock/af_vsock.c
> +++ b/net/vmw_vsock/af_vsock.c
> @@ -1272,11 +1272,15 @@ static int vsock_dgram_connect(struct socket *sock,
>  int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
>  			size_t len, int flags)
>  {
> +	const struct vsock_transport *transport;
>  #ifdef CONFIG_BPF_SYSCALL
>  	const struct proto *prot;
>  #endif
>  	struct vsock_sock *vsk;
> +	struct sk_buff *skb;
> +	size_t payload_len;
>  	struct sock *sk;
> +	int err;
>  
>  	sk = sock->sk;
>  	vsk = vsock_sk(sk);
> @@ -1287,7 +1291,41 @@ int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
>  		return prot->recvmsg(sk, msg, len, flags, NULL);
>  #endif
>  
> -	return vsk->transport->dgram_dequeue(vsk, msg, len, flags);
> +	if (flags & MSG_OOB || flags & MSG_ERRQUEUE)
> +		return -EOPNOTSUPP;
> +
> +	transport = vsk->transport;
> +
> +	/* Retrieve the head sk_buff from the socket's receive queue. */
> +	err = 0;
> +	skb = skb_recv_datagram(sk_vsock(vsk), flags, &err);
> +	if (!skb)
> +		return err;
> +
> +	payload_len = skb->len;
> +
> +	if (payload_len > len) {
> +		payload_len = len;
> +		msg->msg_flags |= MSG_TRUNC;
> +	}
> +
> +	/* Place the datagram payload in the user's iovec. */
> +	err = skb_copy_datagram_msg(skb, 0, msg, payload_len);
> +	if (err)
> +		goto out;
> +
> +	if (msg->msg_name) {
> +		/* Provide the address of the sender. */
> +		DECLARE_SOCKADDR(struct sockaddr_vm *, vm_addr, msg->msg_name);
> +
> +		transport->dgram_addr_init(skb, vm_addr);

Do we need check that dgram_addr_init != NULL? because I see that not all transports have this
callback set in this patch

> +		msg->msg_namelen = sizeof(*vm_addr);
> +	}
> +	err = payload_len;
> +
> +out:
> +	skb_free_datagram(&vsk->sk, skb);
> +	return err;
>  }
>  EXPORT_SYMBOL_GPL(vsock_dgram_recvmsg);
>  
> diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
> index 7cb1a9d2cdb4..7f1ea434656d 100644
> --- a/net/vmw_vsock/hyperv_transport.c
> +++ b/net/vmw_vsock/hyperv_transport.c
> @@ -556,12 +556,6 @@ static int hvs_dgram_bind(struct vsock_sock *vsk, struct sockaddr_vm *addr)
>  	return -EOPNOTSUPP;
>  }
>  
> -static int hvs_dgram_dequeue(struct vsock_sock *vsk, struct msghdr *msg,
> -			     size_t len, int flags)
> -{
> -	return -EOPNOTSUPP;
> -}
> -
>  static int hvs_dgram_enqueue(struct vsock_sock *vsk,
>  			     struct sockaddr_vm *remote, struct msghdr *msg,
>  			     size_t dgram_len)
> @@ -833,7 +827,6 @@ static struct vsock_transport hvs_transport = {
>  	.shutdown                 = hvs_shutdown,
>  
>  	.dgram_bind               = hvs_dgram_bind,
> -	.dgram_dequeue            = hvs_dgram_dequeue,
>  	.dgram_enqueue            = hvs_dgram_enqueue,
>  	.dgram_allow              = hvs_dgram_allow,
>  
> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
> index e95df847176b..66edffdbf303 100644
> --- a/net/vmw_vsock/virtio_transport.c
> +++ b/net/vmw_vsock/virtio_transport.c
> @@ -429,7 +429,6 @@ static struct virtio_transport virtio_transport = {
>  		.cancel_pkt               = virtio_transport_cancel_pkt,
>  
>  		.dgram_bind               = virtio_transport_dgram_bind,
> -		.dgram_dequeue            = virtio_transport_dgram_dequeue,
>  		.dgram_enqueue            = virtio_transport_dgram_enqueue,
>  		.dgram_allow              = virtio_transport_dgram_allow,
>  
> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
> index b769fc258931..01ea1402ad40 100644
> --- a/net/vmw_vsock/virtio_transport_common.c
> +++ b/net/vmw_vsock/virtio_transport_common.c
> @@ -583,15 +583,6 @@ virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
>  }
>  EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_enqueue);
>  
> -int
> -virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
> -			       struct msghdr *msg,
> -			       size_t len, int flags)
> -{
> -	return -EOPNOTSUPP;
> -}
> -EXPORT_SYMBOL_GPL(virtio_transport_dgram_dequeue);
> -
>  s64 virtio_transport_stream_has_data(struct vsock_sock *vsk)
>  {
>  	struct virtio_vsock_sock *vvs = vsk->trans;
> diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.c
> index b370070194fa..0bbbdb222245 100644
> --- a/net/vmw_vsock/vmci_transport.c
> +++ b/net/vmw_vsock/vmci_transport.c
> @@ -641,6 +641,7 @@ static int vmci_transport_recv_dgram_cb(void *data, struct vmci_datagram *dg)
>  	sock_hold(sk);
>  	skb_put(skb, size);
>  	memcpy(skb->data, dg, size);
> +	skb_pull(skb, VMCI_DG_HEADERSIZE);
>  	sk_receive_skb(sk, skb, 0);
>  
>  	return VMCI_SUCCESS;
> @@ -1731,57 +1732,18 @@ static int vmci_transport_dgram_enqueue(
>  	return err - sizeof(*dg);
>  }
>  
> -static int vmci_transport_dgram_dequeue(struct vsock_sock *vsk,
> -					struct msghdr *msg, size_t len,
> -					int flags)
> +static void vmci_transport_dgram_addr_init(struct sk_buff *skb,
> +					   struct sockaddr_vm *addr)
>  {
> -	int err;
>  	struct vmci_datagram *dg;
> -	size_t payload_len;
> -	struct sk_buff *skb;
> -
> -	if (flags & MSG_OOB || flags & MSG_ERRQUEUE)
> -		return -EOPNOTSUPP;
> -
> -	/* Retrieve the head sk_buff from the socket's receive queue. */
> -	err = 0;
> -	skb = skb_recv_datagram(&vsk->sk, flags, &err);
> -	if (!skb)
> -		return err;
> -
> -	dg = (struct vmci_datagram *)skb->data;
> -	if (!dg)
> -		/* err is 0, meaning we read zero bytes. */
> -		goto out;
> -
> -	payload_len = dg->payload_size;
> -	/* Ensure the sk_buff matches the payload size claimed in the packet. */
> -	if (payload_len != skb->len - sizeof(*dg)) {
> -		err = -EINVAL;
> -		goto out;
> -	}
> -
> -	if (payload_len > len) {
> -		payload_len = len;
> -		msg->msg_flags |= MSG_TRUNC;
> -	}
> +	unsigned int cid, port;
>  
> -	/* Place the datagram payload in the user's iovec. */
> -	err = skb_copy_datagram_msg(skb, sizeof(*dg), msg, payload_len);
> -	if (err)
> -		goto out;
> -
> -	if (msg->msg_name) {
> -		/* Provide the address of the sender. */
> -		DECLARE_SOCKADDR(struct sockaddr_vm *, vm_addr, msg->msg_name);
> -		vsock_addr_init(vm_addr, dg->src.context, dg->src.resource);
> -		msg->msg_namelen = sizeof(*vm_addr);
> -	}
> -	err = payload_len;
> +	WARN_ONCE(skb->head == skb->data, "vmci vsock bug: bad dgram skb");
>  
> -out:
> -	skb_free_datagram(&vsk->sk, skb);
> -	return err;
> +	dg = (struct vmci_datagram *)skb->head;
> +	cid = dg->src.context;
> +	port = dg->src.resource;
> +	vsock_addr_init(addr, cid, port);

I think we

1) can short this to:

vsock_addr_init(addr, dg->src.context, dg->src.resource);

2) w/o previous point, cid and port better be u32, as VMCI structure has u32 fields 'context' and
   'resource' and 'vsock_addr_init()' also has u32 type for both arguments.

Thanks, Arseniy

>  }
>  
>  static bool vmci_transport_dgram_allow(u32 cid, u32 port)
> @@ -2040,9 +2002,9 @@ static struct vsock_transport vmci_transport = {
>  	.release = vmci_transport_release,
>  	.connect = vmci_transport_connect,
>  	.dgram_bind = vmci_transport_dgram_bind,
> -	.dgram_dequeue = vmci_transport_dgram_dequeue,
>  	.dgram_enqueue = vmci_transport_dgram_enqueue,
>  	.dgram_allow = vmci_transport_dgram_allow,
> +	.dgram_addr_init = vmci_transport_dgram_addr_init,
>  	.stream_dequeue = vmci_transport_stream_dequeue,
>  	.stream_enqueue = vmci_transport_stream_enqueue,
>  	.stream_has_data = vmci_transport_stream_has_data,
> diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c
> index 5c6360df1f31..2a59dd177c74 100644
> --- a/net/vmw_vsock/vsock_loopback.c
> +++ b/net/vmw_vsock/vsock_loopback.c
> @@ -62,7 +62,6 @@ static struct virtio_transport loopback_transport = {
>  		.cancel_pkt               = vsock_loopback_cancel_pkt,
>  
>  		.dgram_bind               = virtio_transport_dgram_bind,
> -		.dgram_dequeue            = virtio_transport_dgram_dequeue,
>  		.dgram_enqueue            = virtio_transport_dgram_enqueue,
>  		.dgram_allow              = virtio_transport_dgram_allow,
>  
>
  
Bobby Eshleman July 26, 2023, 6:21 p.m. UTC | #2
On Mon, Jul 24, 2023 at 09:11:44PM +0300, Arseniy Krasnov wrote:
> 
> 
> On 19.07.2023 03:50, Bobby Eshleman wrote:
> > This commit drops the transport->dgram_dequeue callback and makes
> > vsock_dgram_recvmsg() generic to all transports.
> > 
> > To make this possible, two transport-level changes are introduced:
> > - implementation of the ->dgram_addr_init() callback to initialize
> >   the sockaddr_vm structure with data from incoming socket buffers.
> > - transport implementations set the skb->data pointer to the beginning
> >   of the payload prior to adding the skb to the socket's receive queue.
> >   That is, they must use skb_pull() before enqueuing. This is an
> >   agreement between the transport and the socket layer that skb->data
> >   always points to the beginning of the payload (and not, for example,
> >   the packet header).
> > 
> > Signed-off-by: Bobby Eshleman <bobby.eshleman@bytedance.com>
> > ---
> >  drivers/vhost/vsock.c                   |  1 -
> >  include/linux/virtio_vsock.h            |  5 ---
> >  include/net/af_vsock.h                  |  3 +-
> >  net/vmw_vsock/af_vsock.c                | 40 ++++++++++++++++++++++-
> >  net/vmw_vsock/hyperv_transport.c        |  7 ----
> >  net/vmw_vsock/virtio_transport.c        |  1 -
> >  net/vmw_vsock/virtio_transport_common.c |  9 -----
> >  net/vmw_vsock/vmci_transport.c          | 58 ++++++---------------------------
> >  net/vmw_vsock/vsock_loopback.c          |  1 -
> >  9 files changed, 50 insertions(+), 75 deletions(-)
> > 
> > diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> > index 6578db78f0ae..ae8891598a48 100644
> > --- a/drivers/vhost/vsock.c
> > +++ b/drivers/vhost/vsock.c
> > @@ -410,7 +410,6 @@ static struct virtio_transport vhost_transport = {
> >  		.cancel_pkt               = vhost_transport_cancel_pkt,
> >  
> >  		.dgram_enqueue            = virtio_transport_dgram_enqueue,
> > -		.dgram_dequeue            = virtio_transport_dgram_dequeue,
> >  		.dgram_bind               = virtio_transport_dgram_bind,
> >  		.dgram_allow              = virtio_transport_dgram_allow,
> >  
> > diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
> > index c58453699ee9..18cbe8d37fca 100644
> > --- a/include/linux/virtio_vsock.h
> > +++ b/include/linux/virtio_vsock.h
> > @@ -167,11 +167,6 @@ virtio_transport_stream_dequeue(struct vsock_sock *vsk,
> >  				size_t len,
> >  				int type);
> >  int
> > -virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
> > -			       struct msghdr *msg,
> > -			       size_t len, int flags);
> > -
> > -int
> >  virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
> >  				   struct msghdr *msg,
> >  				   size_t len);
> > diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
> > index 0e7504a42925..305d57502e89 100644
> > --- a/include/net/af_vsock.h
> > +++ b/include/net/af_vsock.h
> > @@ -120,11 +120,10 @@ struct vsock_transport {
> >  
> >  	/* DGRAM. */
> >  	int (*dgram_bind)(struct vsock_sock *, struct sockaddr_vm *);
> > -	int (*dgram_dequeue)(struct vsock_sock *vsk, struct msghdr *msg,
> > -			     size_t len, int flags);
> >  	int (*dgram_enqueue)(struct vsock_sock *, struct sockaddr_vm *,
> >  			     struct msghdr *, size_t len);
> >  	bool (*dgram_allow)(u32 cid, u32 port);
> > +	void (*dgram_addr_init)(struct sk_buff *skb, struct sockaddr_vm *addr);
> >  
> >  	/* STREAM. */
> >  	/* TODO: stream_bind() */
> > diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> > index deb72a8c44a7..ad71e084bf2f 100644
> > --- a/net/vmw_vsock/af_vsock.c
> > +++ b/net/vmw_vsock/af_vsock.c
> > @@ -1272,11 +1272,15 @@ static int vsock_dgram_connect(struct socket *sock,
> >  int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
> >  			size_t len, int flags)
> >  {
> > +	const struct vsock_transport *transport;
> >  #ifdef CONFIG_BPF_SYSCALL
> >  	const struct proto *prot;
> >  #endif
> >  	struct vsock_sock *vsk;
> > +	struct sk_buff *skb;
> > +	size_t payload_len;
> >  	struct sock *sk;
> > +	int err;
> >  
> >  	sk = sock->sk;
> >  	vsk = vsock_sk(sk);
> > @@ -1287,7 +1291,41 @@ int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
> >  		return prot->recvmsg(sk, msg, len, flags, NULL);
> >  #endif
> >  
> > -	return vsk->transport->dgram_dequeue(vsk, msg, len, flags);
> > +	if (flags & MSG_OOB || flags & MSG_ERRQUEUE)
> > +		return -EOPNOTSUPP;
> > +
> > +	transport = vsk->transport;
> > +
> > +	/* Retrieve the head sk_buff from the socket's receive queue. */
> > +	err = 0;
> > +	skb = skb_recv_datagram(sk_vsock(vsk), flags, &err);
> > +	if (!skb)
> > +		return err;
> > +
> > +	payload_len = skb->len;
> > +
> > +	if (payload_len > len) {
> > +		payload_len = len;
> > +		msg->msg_flags |= MSG_TRUNC;
> > +	}
> > +
> > +	/* Place the datagram payload in the user's iovec. */
> > +	err = skb_copy_datagram_msg(skb, 0, msg, payload_len);
> > +	if (err)
> > +		goto out;
> > +
> > +	if (msg->msg_name) {
> > +		/* Provide the address of the sender. */
> > +		DECLARE_SOCKADDR(struct sockaddr_vm *, vm_addr, msg->msg_name);
> > +
> > +		transport->dgram_addr_init(skb, vm_addr);
> 
> Do we need check that dgram_addr_init != NULL? because I see that not all transports have this
> callback set in this patch
> 

How about adding the check somewhere outside of the hotpath, such as
when the transport is assigned?

> > +		msg->msg_namelen = sizeof(*vm_addr);
> > +	}
> > +	err = payload_len;
> > +
> > +out:
> > +	skb_free_datagram(&vsk->sk, skb);
> > +	return err;
> >  }
> >  EXPORT_SYMBOL_GPL(vsock_dgram_recvmsg);
> >  
> > diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
> > index 7cb1a9d2cdb4..7f1ea434656d 100644
> > --- a/net/vmw_vsock/hyperv_transport.c
> > +++ b/net/vmw_vsock/hyperv_transport.c
> > @@ -556,12 +556,6 @@ static int hvs_dgram_bind(struct vsock_sock *vsk, struct sockaddr_vm *addr)
> >  	return -EOPNOTSUPP;
> >  }
> >  
> > -static int hvs_dgram_dequeue(struct vsock_sock *vsk, struct msghdr *msg,
> > -			     size_t len, int flags)
> > -{
> > -	return -EOPNOTSUPP;
> > -}
> > -
> >  static int hvs_dgram_enqueue(struct vsock_sock *vsk,
> >  			     struct sockaddr_vm *remote, struct msghdr *msg,
> >  			     size_t dgram_len)
> > @@ -833,7 +827,6 @@ static struct vsock_transport hvs_transport = {
> >  	.shutdown                 = hvs_shutdown,
> >  
> >  	.dgram_bind               = hvs_dgram_bind,
> > -	.dgram_dequeue            = hvs_dgram_dequeue,
> >  	.dgram_enqueue            = hvs_dgram_enqueue,
> >  	.dgram_allow              = hvs_dgram_allow,
> >  
> > diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
> > index e95df847176b..66edffdbf303 100644
> > --- a/net/vmw_vsock/virtio_transport.c
> > +++ b/net/vmw_vsock/virtio_transport.c
> > @@ -429,7 +429,6 @@ static struct virtio_transport virtio_transport = {
> >  		.cancel_pkt               = virtio_transport_cancel_pkt,
> >  
> >  		.dgram_bind               = virtio_transport_dgram_bind,
> > -		.dgram_dequeue            = virtio_transport_dgram_dequeue,
> >  		.dgram_enqueue            = virtio_transport_dgram_enqueue,
> >  		.dgram_allow              = virtio_transport_dgram_allow,
> >  
> > diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
> > index b769fc258931..01ea1402ad40 100644
> > --- a/net/vmw_vsock/virtio_transport_common.c
> > +++ b/net/vmw_vsock/virtio_transport_common.c
> > @@ -583,15 +583,6 @@ virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
> >  }
> >  EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_enqueue);
> >  
> > -int
> > -virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
> > -			       struct msghdr *msg,
> > -			       size_t len, int flags)
> > -{
> > -	return -EOPNOTSUPP;
> > -}
> > -EXPORT_SYMBOL_GPL(virtio_transport_dgram_dequeue);
> > -
> >  s64 virtio_transport_stream_has_data(struct vsock_sock *vsk)
> >  {
> >  	struct virtio_vsock_sock *vvs = vsk->trans;
> > diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.c
> > index b370070194fa..0bbbdb222245 100644
> > --- a/net/vmw_vsock/vmci_transport.c
> > +++ b/net/vmw_vsock/vmci_transport.c
> > @@ -641,6 +641,7 @@ static int vmci_transport_recv_dgram_cb(void *data, struct vmci_datagram *dg)
> >  	sock_hold(sk);
> >  	skb_put(skb, size);
> >  	memcpy(skb->data, dg, size);
> > +	skb_pull(skb, VMCI_DG_HEADERSIZE);
> >  	sk_receive_skb(sk, skb, 0);
> >  
> >  	return VMCI_SUCCESS;
> > @@ -1731,57 +1732,18 @@ static int vmci_transport_dgram_enqueue(
> >  	return err - sizeof(*dg);
> >  }
> >  
> > -static int vmci_transport_dgram_dequeue(struct vsock_sock *vsk,
> > -					struct msghdr *msg, size_t len,
> > -					int flags)
> > +static void vmci_transport_dgram_addr_init(struct sk_buff *skb,
> > +					   struct sockaddr_vm *addr)
> >  {
> > -	int err;
> >  	struct vmci_datagram *dg;
> > -	size_t payload_len;
> > -	struct sk_buff *skb;
> > -
> > -	if (flags & MSG_OOB || flags & MSG_ERRQUEUE)
> > -		return -EOPNOTSUPP;
> > -
> > -	/* Retrieve the head sk_buff from the socket's receive queue. */
> > -	err = 0;
> > -	skb = skb_recv_datagram(&vsk->sk, flags, &err);
> > -	if (!skb)
> > -		return err;
> > -
> > -	dg = (struct vmci_datagram *)skb->data;
> > -	if (!dg)
> > -		/* err is 0, meaning we read zero bytes. */
> > -		goto out;
> > -
> > -	payload_len = dg->payload_size;
> > -	/* Ensure the sk_buff matches the payload size claimed in the packet. */
> > -	if (payload_len != skb->len - sizeof(*dg)) {
> > -		err = -EINVAL;
> > -		goto out;
> > -	}
> > -
> > -	if (payload_len > len) {
> > -		payload_len = len;
> > -		msg->msg_flags |= MSG_TRUNC;
> > -	}
> > +	unsigned int cid, port;
> >  
> > -	/* Place the datagram payload in the user's iovec. */
> > -	err = skb_copy_datagram_msg(skb, sizeof(*dg), msg, payload_len);
> > -	if (err)
> > -		goto out;
> > -
> > -	if (msg->msg_name) {
> > -		/* Provide the address of the sender. */
> > -		DECLARE_SOCKADDR(struct sockaddr_vm *, vm_addr, msg->msg_name);
> > -		vsock_addr_init(vm_addr, dg->src.context, dg->src.resource);
> > -		msg->msg_namelen = sizeof(*vm_addr);
> > -	}
> > -	err = payload_len;
> > +	WARN_ONCE(skb->head == skb->data, "vmci vsock bug: bad dgram skb");
> >  
> > -out:
> > -	skb_free_datagram(&vsk->sk, skb);
> > -	return err;
> > +	dg = (struct vmci_datagram *)skb->head;
> > +	cid = dg->src.context;
> > +	port = dg->src.resource;
> > +	vsock_addr_init(addr, cid, port);
> 
> I think we
> 
> 1) can short this to:
> 
> vsock_addr_init(addr, dg->src.context, dg->src.resource);
> 
> 2) w/o previous point, cid and port better be u32, as VMCI structure has u32 fields 'context' and
>    'resource' and 'vsock_addr_init()' also has u32 type for both arguments.
> 
> Thanks, Arseniy

Sounds good, thanks.

> 
> >  }
> >  
> >  static bool vmci_transport_dgram_allow(u32 cid, u32 port)
> > @@ -2040,9 +2002,9 @@ static struct vsock_transport vmci_transport = {
> >  	.release = vmci_transport_release,
> >  	.connect = vmci_transport_connect,
> >  	.dgram_bind = vmci_transport_dgram_bind,
> > -	.dgram_dequeue = vmci_transport_dgram_dequeue,
> >  	.dgram_enqueue = vmci_transport_dgram_enqueue,
> >  	.dgram_allow = vmci_transport_dgram_allow,
> > +	.dgram_addr_init = vmci_transport_dgram_addr_init,
> >  	.stream_dequeue = vmci_transport_stream_dequeue,
> >  	.stream_enqueue = vmci_transport_stream_enqueue,
> >  	.stream_has_data = vmci_transport_stream_has_data,
> > diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c
> > index 5c6360df1f31..2a59dd177c74 100644
> > --- a/net/vmw_vsock/vsock_loopback.c
> > +++ b/net/vmw_vsock/vsock_loopback.c
> > @@ -62,7 +62,6 @@ static struct virtio_transport loopback_transport = {
> >  		.cancel_pkt               = vsock_loopback_cancel_pkt,
> >  
> >  		.dgram_bind               = virtio_transport_dgram_bind,
> > -		.dgram_dequeue            = virtio_transport_dgram_dequeue,
> >  		.dgram_enqueue            = virtio_transport_dgram_enqueue,
> >  		.dgram_allow              = virtio_transport_dgram_allow,
> >  
> > 

Thanks,
Bobby
  
Arseniy Krasnov July 27, 2023, 7:53 a.m. UTC | #3
On 26.07.2023 21:21, Bobby Eshleman wrote:
> On Mon, Jul 24, 2023 at 09:11:44PM +0300, Arseniy Krasnov wrote:
>>
>>
>> On 19.07.2023 03:50, Bobby Eshleman wrote:
>>> This commit drops the transport->dgram_dequeue callback and makes
>>> vsock_dgram_recvmsg() generic to all transports.
>>>
>>> To make this possible, two transport-level changes are introduced:
>>> - implementation of the ->dgram_addr_init() callback to initialize
>>>   the sockaddr_vm structure with data from incoming socket buffers.
>>> - transport implementations set the skb->data pointer to the beginning
>>>   of the payload prior to adding the skb to the socket's receive queue.
>>>   That is, they must use skb_pull() before enqueuing. This is an
>>>   agreement between the transport and the socket layer that skb->data
>>>   always points to the beginning of the payload (and not, for example,
>>>   the packet header).
>>>
>>> Signed-off-by: Bobby Eshleman <bobby.eshleman@bytedance.com>
>>> ---
>>>  drivers/vhost/vsock.c                   |  1 -
>>>  include/linux/virtio_vsock.h            |  5 ---
>>>  include/net/af_vsock.h                  |  3 +-
>>>  net/vmw_vsock/af_vsock.c                | 40 ++++++++++++++++++++++-
>>>  net/vmw_vsock/hyperv_transport.c        |  7 ----
>>>  net/vmw_vsock/virtio_transport.c        |  1 -
>>>  net/vmw_vsock/virtio_transport_common.c |  9 -----
>>>  net/vmw_vsock/vmci_transport.c          | 58 ++++++---------------------------
>>>  net/vmw_vsock/vsock_loopback.c          |  1 -
>>>  9 files changed, 50 insertions(+), 75 deletions(-)
>>>
>>> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
>>> index 6578db78f0ae..ae8891598a48 100644
>>> --- a/drivers/vhost/vsock.c
>>> +++ b/drivers/vhost/vsock.c
>>> @@ -410,7 +410,6 @@ static struct virtio_transport vhost_transport = {
>>>  		.cancel_pkt               = vhost_transport_cancel_pkt,
>>>  
>>>  		.dgram_enqueue            = virtio_transport_dgram_enqueue,
>>> -		.dgram_dequeue            = virtio_transport_dgram_dequeue,
>>>  		.dgram_bind               = virtio_transport_dgram_bind,
>>>  		.dgram_allow              = virtio_transport_dgram_allow,
>>>  
>>> diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
>>> index c58453699ee9..18cbe8d37fca 100644
>>> --- a/include/linux/virtio_vsock.h
>>> +++ b/include/linux/virtio_vsock.h
>>> @@ -167,11 +167,6 @@ virtio_transport_stream_dequeue(struct vsock_sock *vsk,
>>>  				size_t len,
>>>  				int type);
>>>  int
>>> -virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
>>> -			       struct msghdr *msg,
>>> -			       size_t len, int flags);
>>> -
>>> -int
>>>  virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
>>>  				   struct msghdr *msg,
>>>  				   size_t len);
>>> diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
>>> index 0e7504a42925..305d57502e89 100644
>>> --- a/include/net/af_vsock.h
>>> +++ b/include/net/af_vsock.h
>>> @@ -120,11 +120,10 @@ struct vsock_transport {
>>>  
>>>  	/* DGRAM. */
>>>  	int (*dgram_bind)(struct vsock_sock *, struct sockaddr_vm *);
>>> -	int (*dgram_dequeue)(struct vsock_sock *vsk, struct msghdr *msg,
>>> -			     size_t len, int flags);
>>>  	int (*dgram_enqueue)(struct vsock_sock *, struct sockaddr_vm *,
>>>  			     struct msghdr *, size_t len);
>>>  	bool (*dgram_allow)(u32 cid, u32 port);
>>> +	void (*dgram_addr_init)(struct sk_buff *skb, struct sockaddr_vm *addr);
>>>  
>>>  	/* STREAM. */
>>>  	/* TODO: stream_bind() */
>>> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>>> index deb72a8c44a7..ad71e084bf2f 100644
>>> --- a/net/vmw_vsock/af_vsock.c
>>> +++ b/net/vmw_vsock/af_vsock.c
>>> @@ -1272,11 +1272,15 @@ static int vsock_dgram_connect(struct socket *sock,
>>>  int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
>>>  			size_t len, int flags)
>>>  {
>>> +	const struct vsock_transport *transport;
>>>  #ifdef CONFIG_BPF_SYSCALL
>>>  	const struct proto *prot;
>>>  #endif
>>>  	struct vsock_sock *vsk;
>>> +	struct sk_buff *skb;
>>> +	size_t payload_len;
>>>  	struct sock *sk;
>>> +	int err;
>>>  
>>>  	sk = sock->sk;
>>>  	vsk = vsock_sk(sk);
>>> @@ -1287,7 +1291,41 @@ int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
>>>  		return prot->recvmsg(sk, msg, len, flags, NULL);
>>>  #endif
>>>  
>>> -	return vsk->transport->dgram_dequeue(vsk, msg, len, flags);
>>> +	if (flags & MSG_OOB || flags & MSG_ERRQUEUE)
>>> +		return -EOPNOTSUPP;
>>> +
>>> +	transport = vsk->transport;
>>> +
>>> +	/* Retrieve the head sk_buff from the socket's receive queue. */
>>> +	err = 0;
>>> +	skb = skb_recv_datagram(sk_vsock(vsk), flags, &err);
>>> +	if (!skb)
>>> +		return err;
>>> +
>>> +	payload_len = skb->len;
>>> +
>>> +	if (payload_len > len) {
>>> +		payload_len = len;
>>> +		msg->msg_flags |= MSG_TRUNC;
>>> +	}
>>> +
>>> +	/* Place the datagram payload in the user's iovec. */
>>> +	err = skb_copy_datagram_msg(skb, 0, msg, payload_len);
>>> +	if (err)
>>> +		goto out;
>>> +
>>> +	if (msg->msg_name) {
>>> +		/* Provide the address of the sender. */
>>> +		DECLARE_SOCKADDR(struct sockaddr_vm *, vm_addr, msg->msg_name);
>>> +
>>> +		transport->dgram_addr_init(skb, vm_addr);
>>
>> Do we need check that dgram_addr_init != NULL? because I see that not all transports have this
>> callback set in this patch
>>
> 
> How about adding the check somewhere outside of the hotpath, such as
> when the transport is assigned?

Yes, may be we can return ESOCKTNOSUPPORT if this callback is not provided by transport (as we dereference
it here without any checks).

Thanks, Arseniy

> 
>>> +		msg->msg_namelen = sizeof(*vm_addr);
>>> +	}
>>> +	err = payload_len;
>>> +
>>> +out:
>>> +	skb_free_datagram(&vsk->sk, skb);
>>> +	return err;
>>>  }
>>>  EXPORT_SYMBOL_GPL(vsock_dgram_recvmsg);
>>>  
>>> diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
>>> index 7cb1a9d2cdb4..7f1ea434656d 100644
>>> --- a/net/vmw_vsock/hyperv_transport.c
>>> +++ b/net/vmw_vsock/hyperv_transport.c
>>> @@ -556,12 +556,6 @@ static int hvs_dgram_bind(struct vsock_sock *vsk, struct sockaddr_vm *addr)
>>>  	return -EOPNOTSUPP;
>>>  }
>>>  
>>> -static int hvs_dgram_dequeue(struct vsock_sock *vsk, struct msghdr *msg,
>>> -			     size_t len, int flags)
>>> -{
>>> -	return -EOPNOTSUPP;
>>> -}
>>> -
>>>  static int hvs_dgram_enqueue(struct vsock_sock *vsk,
>>>  			     struct sockaddr_vm *remote, struct msghdr *msg,
>>>  			     size_t dgram_len)
>>> @@ -833,7 +827,6 @@ static struct vsock_transport hvs_transport = {
>>>  	.shutdown                 = hvs_shutdown,
>>>  
>>>  	.dgram_bind               = hvs_dgram_bind,
>>> -	.dgram_dequeue            = hvs_dgram_dequeue,
>>>  	.dgram_enqueue            = hvs_dgram_enqueue,
>>>  	.dgram_allow              = hvs_dgram_allow,
>>>  
>>> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
>>> index e95df847176b..66edffdbf303 100644
>>> --- a/net/vmw_vsock/virtio_transport.c
>>> +++ b/net/vmw_vsock/virtio_transport.c
>>> @@ -429,7 +429,6 @@ static struct virtio_transport virtio_transport = {
>>>  		.cancel_pkt               = virtio_transport_cancel_pkt,
>>>  
>>>  		.dgram_bind               = virtio_transport_dgram_bind,
>>> -		.dgram_dequeue            = virtio_transport_dgram_dequeue,
>>>  		.dgram_enqueue            = virtio_transport_dgram_enqueue,
>>>  		.dgram_allow              = virtio_transport_dgram_allow,
>>>  
>>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>>> index b769fc258931..01ea1402ad40 100644
>>> --- a/net/vmw_vsock/virtio_transport_common.c
>>> +++ b/net/vmw_vsock/virtio_transport_common.c
>>> @@ -583,15 +583,6 @@ virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
>>>  }
>>>  EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_enqueue);
>>>  
>>> -int
>>> -virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
>>> -			       struct msghdr *msg,
>>> -			       size_t len, int flags)
>>> -{
>>> -	return -EOPNOTSUPP;
>>> -}
>>> -EXPORT_SYMBOL_GPL(virtio_transport_dgram_dequeue);
>>> -
>>>  s64 virtio_transport_stream_has_data(struct vsock_sock *vsk)
>>>  {
>>>  	struct virtio_vsock_sock *vvs = vsk->trans;
>>> diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.c
>>> index b370070194fa..0bbbdb222245 100644
>>> --- a/net/vmw_vsock/vmci_transport.c
>>> +++ b/net/vmw_vsock/vmci_transport.c
>>> @@ -641,6 +641,7 @@ static int vmci_transport_recv_dgram_cb(void *data, struct vmci_datagram *dg)
>>>  	sock_hold(sk);
>>>  	skb_put(skb, size);
>>>  	memcpy(skb->data, dg, size);
>>> +	skb_pull(skb, VMCI_DG_HEADERSIZE);
>>>  	sk_receive_skb(sk, skb, 0);
>>>  
>>>  	return VMCI_SUCCESS;
>>> @@ -1731,57 +1732,18 @@ static int vmci_transport_dgram_enqueue(
>>>  	return err - sizeof(*dg);
>>>  }
>>>  
>>> -static int vmci_transport_dgram_dequeue(struct vsock_sock *vsk,
>>> -					struct msghdr *msg, size_t len,
>>> -					int flags)
>>> +static void vmci_transport_dgram_addr_init(struct sk_buff *skb,
>>> +					   struct sockaddr_vm *addr)
>>>  {
>>> -	int err;
>>>  	struct vmci_datagram *dg;
>>> -	size_t payload_len;
>>> -	struct sk_buff *skb;
>>> -
>>> -	if (flags & MSG_OOB || flags & MSG_ERRQUEUE)
>>> -		return -EOPNOTSUPP;
>>> -
>>> -	/* Retrieve the head sk_buff from the socket's receive queue. */
>>> -	err = 0;
>>> -	skb = skb_recv_datagram(&vsk->sk, flags, &err);
>>> -	if (!skb)
>>> -		return err;
>>> -
>>> -	dg = (struct vmci_datagram *)skb->data;
>>> -	if (!dg)
>>> -		/* err is 0, meaning we read zero bytes. */
>>> -		goto out;
>>> -
>>> -	payload_len = dg->payload_size;
>>> -	/* Ensure the sk_buff matches the payload size claimed in the packet. */
>>> -	if (payload_len != skb->len - sizeof(*dg)) {
>>> -		err = -EINVAL;
>>> -		goto out;
>>> -	}
>>> -
>>> -	if (payload_len > len) {
>>> -		payload_len = len;
>>> -		msg->msg_flags |= MSG_TRUNC;
>>> -	}
>>> +	unsigned int cid, port;
>>>  
>>> -	/* Place the datagram payload in the user's iovec. */
>>> -	err = skb_copy_datagram_msg(skb, sizeof(*dg), msg, payload_len);
>>> -	if (err)
>>> -		goto out;
>>> -
>>> -	if (msg->msg_name) {
>>> -		/* Provide the address of the sender. */
>>> -		DECLARE_SOCKADDR(struct sockaddr_vm *, vm_addr, msg->msg_name);
>>> -		vsock_addr_init(vm_addr, dg->src.context, dg->src.resource);
>>> -		msg->msg_namelen = sizeof(*vm_addr);
>>> -	}
>>> -	err = payload_len;
>>> +	WARN_ONCE(skb->head == skb->data, "vmci vsock bug: bad dgram skb");
>>>  
>>> -out:
>>> -	skb_free_datagram(&vsk->sk, skb);
>>> -	return err;
>>> +	dg = (struct vmci_datagram *)skb->head;
>>> +	cid = dg->src.context;
>>> +	port = dg->src.resource;
>>> +	vsock_addr_init(addr, cid, port);
>>
>> I think we
>>
>> 1) can short this to:
>>
>> vsock_addr_init(addr, dg->src.context, dg->src.resource);
>>
>> 2) w/o previous point, cid and port better be u32, as VMCI structure has u32 fields 'context' and
>>    'resource' and 'vsock_addr_init()' also has u32 type for both arguments.
>>
>> Thanks, Arseniy
> 
> Sounds good, thanks.
> 
>>
>>>  }
>>>  
>>>  static bool vmci_transport_dgram_allow(u32 cid, u32 port)
>>> @@ -2040,9 +2002,9 @@ static struct vsock_transport vmci_transport = {
>>>  	.release = vmci_transport_release,
>>>  	.connect = vmci_transport_connect,
>>>  	.dgram_bind = vmci_transport_dgram_bind,
>>> -	.dgram_dequeue = vmci_transport_dgram_dequeue,
>>>  	.dgram_enqueue = vmci_transport_dgram_enqueue,
>>>  	.dgram_allow = vmci_transport_dgram_allow,
>>> +	.dgram_addr_init = vmci_transport_dgram_addr_init,
>>>  	.stream_dequeue = vmci_transport_stream_dequeue,
>>>  	.stream_enqueue = vmci_transport_stream_enqueue,
>>>  	.stream_has_data = vmci_transport_stream_has_data,
>>> diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c
>>> index 5c6360df1f31..2a59dd177c74 100644
>>> --- a/net/vmw_vsock/vsock_loopback.c
>>> +++ b/net/vmw_vsock/vsock_loopback.c
>>> @@ -62,7 +62,6 @@ static struct virtio_transport loopback_transport = {
>>>  		.cancel_pkt               = vsock_loopback_cancel_pkt,
>>>  
>>>  		.dgram_bind               = virtio_transport_dgram_bind,
>>> -		.dgram_dequeue            = virtio_transport_dgram_dequeue,
>>>  		.dgram_enqueue            = virtio_transport_dgram_enqueue,
>>>  		.dgram_allow              = virtio_transport_dgram_allow,
>>>  
>>>
> 
> Thanks,
> Bobby
  

Patch

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 6578db78f0ae..ae8891598a48 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -410,7 +410,6 @@  static struct virtio_transport vhost_transport = {
 		.cancel_pkt               = vhost_transport_cancel_pkt,
 
 		.dgram_enqueue            = virtio_transport_dgram_enqueue,
-		.dgram_dequeue            = virtio_transport_dgram_dequeue,
 		.dgram_bind               = virtio_transport_dgram_bind,
 		.dgram_allow              = virtio_transport_dgram_allow,
 
diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index c58453699ee9..18cbe8d37fca 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -167,11 +167,6 @@  virtio_transport_stream_dequeue(struct vsock_sock *vsk,
 				size_t len,
 				int type);
 int
-virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
-			       struct msghdr *msg,
-			       size_t len, int flags);
-
-int
 virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
 				   struct msghdr *msg,
 				   size_t len);
diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index 0e7504a42925..305d57502e89 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -120,11 +120,10 @@  struct vsock_transport {
 
 	/* DGRAM. */
 	int (*dgram_bind)(struct vsock_sock *, struct sockaddr_vm *);
-	int (*dgram_dequeue)(struct vsock_sock *vsk, struct msghdr *msg,
-			     size_t len, int flags);
 	int (*dgram_enqueue)(struct vsock_sock *, struct sockaddr_vm *,
 			     struct msghdr *, size_t len);
 	bool (*dgram_allow)(u32 cid, u32 port);
+	void (*dgram_addr_init)(struct sk_buff *skb, struct sockaddr_vm *addr);
 
 	/* STREAM. */
 	/* TODO: stream_bind() */
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index deb72a8c44a7..ad71e084bf2f 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1272,11 +1272,15 @@  static int vsock_dgram_connect(struct socket *sock,
 int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
 			size_t len, int flags)
 {
+	const struct vsock_transport *transport;
 #ifdef CONFIG_BPF_SYSCALL
 	const struct proto *prot;
 #endif
 	struct vsock_sock *vsk;
+	struct sk_buff *skb;
+	size_t payload_len;
 	struct sock *sk;
+	int err;
 
 	sk = sock->sk;
 	vsk = vsock_sk(sk);
@@ -1287,7 +1291,41 @@  int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
 		return prot->recvmsg(sk, msg, len, flags, NULL);
 #endif
 
-	return vsk->transport->dgram_dequeue(vsk, msg, len, flags);
+	if (flags & MSG_OOB || flags & MSG_ERRQUEUE)
+		return -EOPNOTSUPP;
+
+	transport = vsk->transport;
+
+	/* Retrieve the head sk_buff from the socket's receive queue. */
+	err = 0;
+	skb = skb_recv_datagram(sk_vsock(vsk), flags, &err);
+	if (!skb)
+		return err;
+
+	payload_len = skb->len;
+
+	if (payload_len > len) {
+		payload_len = len;
+		msg->msg_flags |= MSG_TRUNC;
+	}
+
+	/* Place the datagram payload in the user's iovec. */
+	err = skb_copy_datagram_msg(skb, 0, msg, payload_len);
+	if (err)
+		goto out;
+
+	if (msg->msg_name) {
+		/* Provide the address of the sender. */
+		DECLARE_SOCKADDR(struct sockaddr_vm *, vm_addr, msg->msg_name);
+
+		transport->dgram_addr_init(skb, vm_addr);
+		msg->msg_namelen = sizeof(*vm_addr);
+	}
+	err = payload_len;
+
+out:
+	skb_free_datagram(&vsk->sk, skb);
+	return err;
 }
 EXPORT_SYMBOL_GPL(vsock_dgram_recvmsg);
 
diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
index 7cb1a9d2cdb4..7f1ea434656d 100644
--- a/net/vmw_vsock/hyperv_transport.c
+++ b/net/vmw_vsock/hyperv_transport.c
@@ -556,12 +556,6 @@  static int hvs_dgram_bind(struct vsock_sock *vsk, struct sockaddr_vm *addr)
 	return -EOPNOTSUPP;
 }
 
-static int hvs_dgram_dequeue(struct vsock_sock *vsk, struct msghdr *msg,
-			     size_t len, int flags)
-{
-	return -EOPNOTSUPP;
-}
-
 static int hvs_dgram_enqueue(struct vsock_sock *vsk,
 			     struct sockaddr_vm *remote, struct msghdr *msg,
 			     size_t dgram_len)
@@ -833,7 +827,6 @@  static struct vsock_transport hvs_transport = {
 	.shutdown                 = hvs_shutdown,
 
 	.dgram_bind               = hvs_dgram_bind,
-	.dgram_dequeue            = hvs_dgram_dequeue,
 	.dgram_enqueue            = hvs_dgram_enqueue,
 	.dgram_allow              = hvs_dgram_allow,
 
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index e95df847176b..66edffdbf303 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -429,7 +429,6 @@  static struct virtio_transport virtio_transport = {
 		.cancel_pkt               = virtio_transport_cancel_pkt,
 
 		.dgram_bind               = virtio_transport_dgram_bind,
-		.dgram_dequeue            = virtio_transport_dgram_dequeue,
 		.dgram_enqueue            = virtio_transport_dgram_enqueue,
 		.dgram_allow              = virtio_transport_dgram_allow,
 
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index b769fc258931..01ea1402ad40 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -583,15 +583,6 @@  virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
 }
 EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_enqueue);
 
-int
-virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
-			       struct msghdr *msg,
-			       size_t len, int flags)
-{
-	return -EOPNOTSUPP;
-}
-EXPORT_SYMBOL_GPL(virtio_transport_dgram_dequeue);
-
 s64 virtio_transport_stream_has_data(struct vsock_sock *vsk)
 {
 	struct virtio_vsock_sock *vvs = vsk->trans;
diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.c
index b370070194fa..0bbbdb222245 100644
--- a/net/vmw_vsock/vmci_transport.c
+++ b/net/vmw_vsock/vmci_transport.c
@@ -641,6 +641,7 @@  static int vmci_transport_recv_dgram_cb(void *data, struct vmci_datagram *dg)
 	sock_hold(sk);
 	skb_put(skb, size);
 	memcpy(skb->data, dg, size);
+	skb_pull(skb, VMCI_DG_HEADERSIZE);
 	sk_receive_skb(sk, skb, 0);
 
 	return VMCI_SUCCESS;
@@ -1731,57 +1732,18 @@  static int vmci_transport_dgram_enqueue(
 	return err - sizeof(*dg);
 }
 
-static int vmci_transport_dgram_dequeue(struct vsock_sock *vsk,
-					struct msghdr *msg, size_t len,
-					int flags)
+static void vmci_transport_dgram_addr_init(struct sk_buff *skb,
+					   struct sockaddr_vm *addr)
 {
-	int err;
 	struct vmci_datagram *dg;
-	size_t payload_len;
-	struct sk_buff *skb;
-
-	if (flags & MSG_OOB || flags & MSG_ERRQUEUE)
-		return -EOPNOTSUPP;
-
-	/* Retrieve the head sk_buff from the socket's receive queue. */
-	err = 0;
-	skb = skb_recv_datagram(&vsk->sk, flags, &err);
-	if (!skb)
-		return err;
-
-	dg = (struct vmci_datagram *)skb->data;
-	if (!dg)
-		/* err is 0, meaning we read zero bytes. */
-		goto out;
-
-	payload_len = dg->payload_size;
-	/* Ensure the sk_buff matches the payload size claimed in the packet. */
-	if (payload_len != skb->len - sizeof(*dg)) {
-		err = -EINVAL;
-		goto out;
-	}
-
-	if (payload_len > len) {
-		payload_len = len;
-		msg->msg_flags |= MSG_TRUNC;
-	}
+	unsigned int cid, port;
 
-	/* Place the datagram payload in the user's iovec. */
-	err = skb_copy_datagram_msg(skb, sizeof(*dg), msg, payload_len);
-	if (err)
-		goto out;
-
-	if (msg->msg_name) {
-		/* Provide the address of the sender. */
-		DECLARE_SOCKADDR(struct sockaddr_vm *, vm_addr, msg->msg_name);
-		vsock_addr_init(vm_addr, dg->src.context, dg->src.resource);
-		msg->msg_namelen = sizeof(*vm_addr);
-	}
-	err = payload_len;
+	WARN_ONCE(skb->head == skb->data, "vmci vsock bug: bad dgram skb");
 
-out:
-	skb_free_datagram(&vsk->sk, skb);
-	return err;
+	dg = (struct vmci_datagram *)skb->head;
+	cid = dg->src.context;
+	port = dg->src.resource;
+	vsock_addr_init(addr, cid, port);
 }
 
 static bool vmci_transport_dgram_allow(u32 cid, u32 port)
@@ -2040,9 +2002,9 @@  static struct vsock_transport vmci_transport = {
 	.release = vmci_transport_release,
 	.connect = vmci_transport_connect,
 	.dgram_bind = vmci_transport_dgram_bind,
-	.dgram_dequeue = vmci_transport_dgram_dequeue,
 	.dgram_enqueue = vmci_transport_dgram_enqueue,
 	.dgram_allow = vmci_transport_dgram_allow,
+	.dgram_addr_init = vmci_transport_dgram_addr_init,
 	.stream_dequeue = vmci_transport_stream_dequeue,
 	.stream_enqueue = vmci_transport_stream_enqueue,
 	.stream_has_data = vmci_transport_stream_has_data,
diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c
index 5c6360df1f31..2a59dd177c74 100644
--- a/net/vmw_vsock/vsock_loopback.c
+++ b/net/vmw_vsock/vsock_loopback.c
@@ -62,7 +62,6 @@  static struct virtio_transport loopback_transport = {
 		.cancel_pkt               = vsock_loopback_cancel_pkt,
 
 		.dgram_bind               = virtio_transport_dgram_bind,
-		.dgram_dequeue            = virtio_transport_dgram_dequeue,
 		.dgram_enqueue            = virtio_transport_dgram_enqueue,
 		.dgram_allow              = virtio_transport_dgram_allow,