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

Bobby Eshleman
2023-07-19T00:50:14Z

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);
+ 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,

--
2.30.2