On Mon, Jul 15, 2024 at 1:02 AM Luigi Leonardi
[off-list ref] wrote:

Hi Amery, Bobby

quoted

From: Bobby Eshleman <redacted>

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).

Like in the other patch, please use imperative in the commit message.

quoted

Signed-off-by: Bobby Eshleman <redacted>
Signed-off-by: Amery Hung <redacted>
---
 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;
+};
+

Running scripts/checkpatch.pl --strict --codespell on the patch shows this error:

 ERROR: open brace '{' following function definitions go on the next line
 #183: FILE: include/net/af_vsock.h:225:
 +static inline struct vsock_skb_cb *vsock_skb_cb(struct sk_buff *skb) {

 total: 1 errors, 0 warnings, 0 checks, 235 lines checked

quoted

 /**** 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);

This if statement is always false!

quoted

+
+     /* 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;
+

nit: I'd remove this blank line.

quoted

+     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

Small changes :)
Rest LGTM!

I will fix the two style issues.

Thank you,
Amery

Thanks,
Luigi