[PATCH RFC net-next v3 1/8] vsock/dgram: generalize recvmsg and drop transport->dgram_dequeue

From: Bobby Eshleman
Date: Tue May 30 2023 - 20:36:00 EST

This commit drops the transport->dgram_dequeue callback and makes
vsock_dgram_recvmsg() generic. It also adds additional transport
callbacks for use by the generic vsock_dgram_recvmsg(), such as for
parsing skbs for CID/port which vary in format per transport.

Signed-off-by: Bobby Eshleman <bobby.eshleman@xxxxxxxxxxxxx>
---
drivers/vhost/vsock.c | 4 +-
include/linux/virtio_vsock.h | 3 ++
include/net/af_vsock.h | 13 ++++++-
net/vmw_vsock/af_vsock.c | 51 ++++++++++++++++++++++++-
net/vmw_vsock/hyperv_transport.c | 17 +++++++--
net/vmw_vsock/virtio_transport.c | 4 +-
net/vmw_vsock/virtio_transport_common.c | 18 +++++++++
net/vmw_vsock/vmci_transport.c | 68 +++++++++++++--------------------
net/vmw_vsock/vsock_loopback.c | 4 +-
9 files changed, 132 insertions(+), 50 deletions(-)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 6578db78f0ae..c8201c070b4b 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -410,9 +410,11 @@ 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,
+ .dgram_get_cid = virtio_transport_dgram_get_cid,
+ .dgram_get_port = virtio_transport_dgram_get_port,
+ .dgram_get_length = virtio_transport_dgram_get_length,

.stream_enqueue = virtio_transport_stream_enqueue,
.stream_dequeue = virtio_transport_stream_dequeue,
diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index c58453699ee9..23521a318cf0 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -219,6 +219,9 @@ bool virtio_transport_stream_allow(u32 cid, u32 port);
int virtio_transport_dgram_bind(struct vsock_sock *vsk,
struct sockaddr_vm *addr);
bool virtio_transport_dgram_allow(u32 cid, u32 port);
+int virtio_transport_dgram_get_cid(struct sk_buff *skb, unsigned int *cid);
+int virtio_transport_dgram_get_port(struct sk_buff *skb, unsigned int *port);
+int virtio_transport_dgram_get_length(struct sk_buff *skb, size_t *len);

int virtio_transport_connect(struct vsock_sock *vsk);

diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index 0e7504a42925..7bedb9ee7e3e 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -120,11 +120,20 @@ 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);
+ int (*dgram_get_cid)(struct sk_buff *skb, unsigned int *cid);
+ int (*dgram_get_port)(struct sk_buff *skb, unsigned int *port);
+ int (*dgram_get_length)(struct sk_buff *skb, size_t *length);
+
+ /* The number of bytes into the buffer at which the payload starts, as
+ * first seen by the receiving socket layer. For example, if the
+ * transport presets the skb pointers using skb_pull(sizeof(header))
+ * than this would be zero, otherwise it would be the size of the
+ * header.
+ */
+ const size_t dgram_payload_offset;

/* STREAM. */
/* TODO: stream_bind() */
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 413407bb646c..7ec0659c6ae5 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1271,11 +1271,15 @@ 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);
@@ -1286,7 +1290,52 @@ 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(&vsk->sk, flags, &err);
+ if (!skb)
+ return err;
+
+ err = transport->dgram_get_length(skb, &payload_len);
+ if (err)
+ 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, transport->dgram_payload_offset, 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);
+ unsigned int cid, port;
+
+ err = transport->dgram_get_cid(skb, &cid);
+ if (err)
+ goto out;
+
+ err = transport->dgram_get_port(skb, &port);
+ if (err)
+ goto out;
+
+ vsock_addr_init(vm_addr, cid, 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 7cb1a9d2cdb4..ff6e87e25fa0 100644
--- a/net/vmw_vsock/hyperv_transport.c
+++ b/net/vmw_vsock/hyperv_transport.c
@@ -556,8 +556,17 @@ 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)
+static int hvs_dgram_get_cid(struct sk_buff *skb, unsigned int *cid)
+{
+ return -EOPNOTSUPP;
+}
+
+static int hvs_dgram_get_port(struct sk_buff *skb, unsigned int *port)
+{
+ return -EOPNOTSUPP;
+}
+
+static int hvs_dgram_get_length(struct sk_buff *skb, size_t *len)
{
return -EOPNOTSUPP;
}
@@ -833,7 +842,9 @@ static struct vsock_transport hvs_transport = {
.shutdown = hvs_shutdown,

.dgram_bind = hvs_dgram_bind,
- .dgram_dequeue = hvs_dgram_dequeue,
+ .dgram_get_cid = hvs_dgram_get_cid,
+ .dgram_get_port = hvs_dgram_get_port,
+ .dgram_get_length = hvs_dgram_get_length,
.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..5763cdf13804 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -429,9 +429,11 @@ 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,
+ .dgram_get_cid = virtio_transport_dgram_get_cid,
+ .dgram_get_port = virtio_transport_dgram_get_port,
+ .dgram_get_length = virtio_transport_dgram_get_length,

.stream_dequeue = virtio_transport_stream_dequeue,
.stream_enqueue = virtio_transport_stream_enqueue,
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index e4878551f140..abd939694a1a 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -797,6 +797,24 @@ int virtio_transport_dgram_bind(struct vsock_sock *vsk,
}
EXPORT_SYMBOL_GPL(virtio_transport_dgram_bind);

+int virtio_transport_dgram_get_cid(struct sk_buff *skb, unsigned int *cid)
+{
+ return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_dgram_get_cid);
+
+int virtio_transport_dgram_get_port(struct sk_buff *skb, unsigned int *port)
+{
+ return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_dgram_get_port);
+
+int virtio_transport_dgram_get_length(struct sk_buff *skb, size_t *len)
+{
+ return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_dgram_get_length);
+
bool virtio_transport_dgram_allow(u32 cid, u32 port)
{
return false;
diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.c
index b370070194fa..b6a51afb74b8 100644
--- a/net/vmw_vsock/vmci_transport.c
+++ b/net/vmw_vsock/vmci_transport.c
@@ -1731,57 +1731,40 @@ 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 vmci_transport_dgram_get_cid(struct sk_buff *skb, unsigned int *cid)
{
- int err;
struct vmci_datagram *dg;
- size_t payload_len;
- struct sk_buff *skb;

- if (flags & MSG_OOB || flags & MSG_ERRQUEUE)
- return -EOPNOTSUPP;
+ dg = (struct vmci_datagram *)skb->data;
+ if (!dg)
+ return -EINVAL;

- /* 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;
+ *cid = dg->src.context;
+ return 0;
+}
+
+int vmci_transport_dgram_get_port(struct sk_buff *skb, unsigned int *port)
+{
+ struct vmci_datagram *dg;

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;
- }
+ return -EINVAL;

- if (payload_len > len) {
- payload_len = len;
- msg->msg_flags |= MSG_TRUNC;
- }
+ *port = dg->src.resource;
+ return 0;
+}

- /* Place the datagram payload in the user's iovec. */
- err = skb_copy_datagram_msg(skb, sizeof(*dg), msg, payload_len);
- if (err)
- goto out;
+int vmci_transport_dgram_get_length(struct sk_buff *skb, size_t *len)
+{
+ struct vmci_datagram *dg;

- 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;
+ dg = (struct vmci_datagram *)skb->data;
+ if (!dg)
+ return -EINVAL;

-out:
- skb_free_datagram(&vsk->sk, skb);
- return err;
+ *len = dg->payload_size;
+ return 0;
}

static bool vmci_transport_dgram_allow(u32 cid, u32 port)
@@ -2040,9 +2023,12 @@ 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_get_cid = vmci_transport_dgram_get_cid,
+ .dgram_get_port = vmci_transport_dgram_get_port,
+ .dgram_get_length = vmci_transport_dgram_get_length,
+ .dgram_payload_offset = sizeof(struct vmci_datagram),
.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 e3afc0c866f5..136061f622b8 100644
--- a/net/vmw_vsock/vsock_loopback.c
+++ b/net/vmw_vsock/vsock_loopback.c
@@ -63,9 +63,11 @@ 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,
+ .dgram_get_cid = virtio_transport_dgram_get_cid,
+ .dgram_get_port = virtio_transport_dgram_get_port,
+ .dgram_get_length = virtio_transport_dgram_get_length,

.stream_dequeue = virtio_transport_stream_dequeue,
.stream_enqueue = virtio_transport_stream_enqueue,

--
2.30.2