From: Bobby Eshleman <bobby.eshle...@bytedance.com>

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:
- transport in the receiving path now stores the cid and port into
  the control buffer of an skb when populating an skb. The information
  later is used to initialize sockaddr_vm structure in recvmsg()
  without referencing vsk->transport.
- 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.eshle...@bytedance.com>
Signed-off-by: Amery Hung <amery.h...@bytedance.com>
---
 drivers/vhost/vsock.c                   |  1 -
 include/linux/virtio_vsock.h            |  5 ---
 include/net/af_vsock.h                  | 11 ++++-
 net/vmw_vsock/af_vsock.c                | 42 +++++++++++++++++-
 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          | 59 +++----------------------
 net/vmw_vsock/vsock_loopback.c          |  1 -
 9 files changed, 55 insertions(+), 81 deletions(-)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index ec20ecff85c7..97fffa914e66 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -419,7 +419,6 @@ 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 c82089dee0c8..8b56b8a19ddd 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -177,11 +177,6 @@ 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 535701efc1e5..7aa1f5f2b1a5 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -120,8 +120,6 @@ 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);
@@ -219,6 +217,15 @@ void vsock_for_each_connected_socket(struct 
vsock_transport *transport,
 int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk);
 bool vsock_find_cid(unsigned int cid);
 
+struct vsock_skb_cb {
+       unsigned int src_cid;
+       unsigned int src_port;
+};
+
+static inline struct vsock_skb_cb *vsock_skb_cb(struct sk_buff *skb) {
+       return (struct vsock_skb_cb *)skb->cb;
+};
+
 /**** TAP ****/
 
 struct vsock_tap {
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 4b040285aa78..5e7d4d99ea2c 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1273,11 +1273,15 @@ static int vsock_dgram_connect(struct socket *sock,
 int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
                        size_t len, int flags)
 {
+       struct vsock_skb_cb *vsock_cb;
 #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);
@@ -1288,7 +1292,43 @@ 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;
+
+       if (unlikely(flags & MSG_ERRQUEUE))
+               return sock_recv_errqueue(sk, msg, len, SOL_VSOCK, 0);
+
+       /* 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);
+
+               vsock_cb = vsock_skb_cb(skb);
+               vsock_addr_init(vm_addr, vsock_cb->src_cid, vsock_cb->src_port);
+               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 e2157e387217..326dd41ee2d5 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 43d405298857..a8c97e95622a 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -508,7 +508,6 @@ 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 16ff976a86e3..4bf73d20c12a 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -810,15 +810,6 @@ 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..b39df3ed8c8d 100644
--- a/net/vmw_vsock/vmci_transport.c
+++ b/net/vmw_vsock/vmci_transport.c
@@ -610,6 +610,7 @@ vmci_transport_datagram_create_hnd(u32 resource_id,
 
 static int vmci_transport_recv_dgram_cb(void *data, struct vmci_datagram *dg)
 {
+       struct vsock_skb_cb *vsock_cb;
        struct sock *sk;
        size_t size;
        struct sk_buff *skb;
@@ -637,10 +638,14 @@ static int vmci_transport_recv_dgram_cb(void *data, 
struct vmci_datagram *dg)
        if (!skb)
                return VMCI_ERROR_NO_MEM;
 
+       vsock_cb = vsock_skb_cb(skb);
+       vsock_cb->src_cid = dg->src.context;
+       vsock_cb->src_port = dg->src.resource;
        /* sk_receive_skb() will do a sock_put(), so hold here. */
        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;
@@ -1731,59 +1736,6 @@ 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)
-{
-       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;
-       }
-
-       /* 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;
-
-out:
-       skb_free_datagram(&vsk->sk, skb);
-       return err;
-}
-
 static bool vmci_transport_dgram_allow(u32 cid, u32 port)
 {
        if (cid == VMADDR_CID_HYPERVISOR) {
@@ -2040,7 +1992,6 @@ 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,
        .stream_dequeue = vmci_transport_stream_dequeue,
diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c
index 6dea6119f5b2..11488887a5cc 100644
--- a/net/vmw_vsock/vsock_loopback.c
+++ b/net/vmw_vsock/vsock_loopback.c
@@ -66,7 +66,6 @@ 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,
 
-- 
2.20.1


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