[PATCH RFC net-next v5 09/14] virtio/vsock: add common datagram recv path

Bobby Eshleman
2023-07-19T00:50:23Z

This commit adds the common datagram receive functionality for virtio
transports. It does not add the vhost/virtio users of that
functionality.

This functionality includes:
- changes to the virtio_transport_recv_pkt() path for finding the
bound socket receiver for incoming packets.
- a virtio_transport_dgram_addr_init() function to be used as the
->dgram_addr_init callback for initializing sockaddr_vm inside
the generic recvmsg() caller.

Signed-off-by: Bobby Eshleman <bobby.eshleman@bytedance.com>
---
include/linux/virtio_vsock.h | 2 +
net/vmw_vsock/virtio_transport_common.c | 92 ++++++++++++++++++++++++++++-----
2 files changed, 81 insertions(+), 13 deletions(-)

diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 7632552bee58..b3856b8a42b3 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -212,6 +212,8 @@ u64 virtio_transport_stream_rcvhiwat(struct vsock_sock *vsk);
bool virtio_transport_stream_is_active(struct vsock_sock *vsk);
bool virtio_transport_stream_allow(u32 cid, u32 port);
bool virtio_transport_dgram_allow(u32 cid, u32 port);
+void virtio_transport_dgram_addr_init(struct sk_buff *skb,
+ struct sockaddr_vm *addr);

int virtio_transport_connect(struct vsock_sock *vsk);

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 3bfaff758433..96118e258097 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -183,7 +183,9 @@ EXPORT_SYMBOL_GPL(virtio_transport_deliver_tap_pkt);

static u16 virtio_transport_get_type(struct sock *sk)
{
- if (sk->sk_type == SOCK_STREAM)
+ if (sk->sk_type == SOCK_DGRAM)
+ return VIRTIO_VSOCK_TYPE_DGRAM;
+ else if (sk->sk_type == SOCK_STREAM)
return VIRTIO_VSOCK_TYPE_STREAM;
else
return VIRTIO_VSOCK_TYPE_SEQPACKET;
@@ -1184,6 +1186,35 @@ virtio_transport_recv_enqueue(struct vsock_sock *vsk,
kfree_skb(skb);
}

+static void
+virtio_transport_dgram_kfree_skb(struct sk_buff *skb, int err)
+{
+ if (err == -ENOMEM)
+ kfree_skb_reason(skb, SKB_DROP_REASON_SOCKET_RCVBUFF);
+ else if (err == -ENOBUFS)
+ kfree_skb_reason(skb, SKB_DROP_REASON_PROTO_MEM);
+ else
+ kfree_skb(skb);
+}
+
+/* This function takes ownership of the skb.
+ *
+ * It either places the skb on the sk_receive_queue or frees it.
+ */
+static void
+virtio_transport_recv_dgram(struct sock *sk, struct sk_buff *skb)
+{
+ int err;
+
+ err = sock_queue_rcv_skb(sk, skb);
+ if (err) {
+ virtio_transport_dgram_kfree_skb(skb, err);
+ return;
+ }
+
+ sk->sk_data_ready(sk);
+}
+
static int
virtio_transport_recv_connected(struct sock *sk,
struct sk_buff *skb)
@@ -1347,7 +1378,8 @@ virtio_transport_recv_listen(struct sock *sk, struct sk_buff *skb,
static bool virtio_transport_valid_type(u16 type)
{
return (type == VIRTIO_VSOCK_TYPE_STREAM) ||
- (type == VIRTIO_VSOCK_TYPE_SEQPACKET);
+ (type == VIRTIO_VSOCK_TYPE_SEQPACKET) ||
+ (type == VIRTIO_VSOCK_TYPE_DGRAM);
}

/* We are under the virtio-vsock's vsock->rx_lock or vhost-vsock's vq->mutex
@@ -1361,40 +1393,52 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
struct vsock_sock *vsk;
struct sock *sk;
bool space_available;
+ u16 type;

vsock_addr_init(&src, le64_to_cpu(hdr->src_cid),
le32_to_cpu(hdr->src_port));
vsock_addr_init(&dst, le64_to_cpu(hdr->dst_cid),
le32_to_cpu(hdr->dst_port));

+ type = le16_to_cpu(hdr->type);
+
trace_virtio_transport_recv_pkt(src.svm_cid, src.svm_port,
dst.svm_cid, dst.svm_port,
le32_to_cpu(hdr->len),
- le16_to_cpu(hdr->type),
+ type,
le16_to_cpu(hdr->op),
le32_to_cpu(hdr->flags),
le32_to_cpu(hdr->buf_alloc),
le32_to_cpu(hdr->fwd_cnt));

- if (!virtio_transport_valid_type(le16_to_cpu(hdr->type))) {
+ if (!virtio_transport_valid_type(type)) {
(void)virtio_transport_reset_no_sock(t, skb);
goto free_pkt;
}

- /* The socket must be in connected or bound table
- * otherwise send reset back
+ /* For stream/seqpacket, the socket must be in connected or bound table
+ * otherwise send reset back.
+ *
+ * For datagrams, no reset is sent back.
*/
sk = vsock_find_connected_socket(&src, &dst);
if (!sk) {
- sk = vsock_find_bound_socket(&dst);
- if (!sk) {
- (void)virtio_transport_reset_no_sock(t, skb);
- goto free_pkt;
+ if (type == VIRTIO_VSOCK_TYPE_DGRAM) {
+ sk = vsock_find_bound_dgram_socket(&dst);
+ if (!sk)
+ goto free_pkt;
+ } else {
+ sk = vsock_find_bound_socket(&dst);
+ if (!sk) {
+ (void)virtio_transport_reset_no_sock(t, skb);
+ goto free_pkt;
+ }
}
}

- if (virtio_transport_get_type(sk) != le16_to_cpu(hdr->type)) {
- (void)virtio_transport_reset_no_sock(t, skb);
+ if (virtio_transport_get_type(sk) != type) {
+ if (type != VIRTIO_VSOCK_TYPE_DGRAM)
+ (void)virtio_transport_reset_no_sock(t, skb);
sock_put(sk);
goto free_pkt;
}
@@ -1410,12 +1454,18 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,

/* Check if sk has been closed before lock_sock */
if (sock_flag(sk, SOCK_DONE)) {
- (void)virtio_transport_reset_no_sock(t, skb);
+ if (type != VIRTIO_VSOCK_TYPE_DGRAM)
+ (void)virtio_transport_reset_no_sock(t, skb);
release_sock(sk);
sock_put(sk);
goto free_pkt;
}

+ if (sk->sk_type == SOCK_DGRAM) {
+ virtio_transport_recv_dgram(sk, skb);
+ goto out;
+ }
+
space_available = virtio_transport_space_update(sk, skb);

/* Update CID in case it has changed after a transport reset event */
@@ -1447,6 +1497,7 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
break;
}

+out:
release_sock(sk);

/* Release refcnt obtained when we fetched this socket out of the
@@ -1515,6 +1566,21 @@ int virtio_transport_read_skb(struct vsock_sock *vsk, skb_read_actor_t recv_acto
}
EXPORT_SYMBOL_GPL(virtio_transport_read_skb);

+void virtio_transport_dgram_addr_init(struct sk_buff *skb,
+ struct sockaddr_vm *addr)
+{
+ struct virtio_vsock_hdr *hdr;
+ unsigned int cid, port;
+
+ WARN_ONCE(skb->head == skb->data, "virtio vsock bug: bad dgram skb");
+
+ hdr = virtio_vsock_hdr(skb);
+ cid = le64_to_cpu(hdr->src_cid);
+ port = le32_to_cpu(hdr->src_port);
+ vsock_addr_init(addr, cid, port);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_dgram_addr_init);
+
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Asias He");
MODULE_DESCRIPTION("common code for virtio vsock");

--
2.30.2