[PATCH RFC net-next v2 1/3] vsock: support sockmap

From: Bobby Eshleman
Date: Mon Jan 30 2023 - 23:36:24 EST

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This patch adds sockmap support for vsock sockets. It is intended to be
usable by all transports, but only the virtio transport is implemented.

Signed-off-by: Bobby Eshleman <bobby.eshleman@xxxxxxxxxxxxx>
---
drivers/vhost/vsock.c | 1 +
include/linux/virtio_vsock.h | 1 +
include/net/af_vsock.h | 17 ++++
net/vmw_vsock/Makefile | 1 +
net/vmw_vsock/af_vsock.c | 55 ++++++++--
net/vmw_vsock/virtio_transport.c | 2 +
net/vmw_vsock/virtio_transport_common.c | 24 +++++
net/vmw_vsock/vsock_bpf.c | 175 ++++++++++++++++++++++++++++++++
net/vmw_vsock/vsock_loopback.c | 2 +
9 files changed, 272 insertions(+), 6 deletions(-)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 1f3b89c885cc..3c6dc036b904 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -439,6 +439,7 @@ static struct virtio_transport vhost_transport = {
.notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
.notify_buffer_size = virtio_transport_notify_buffer_size,

+ .read_skb = virtio_transport_read_skb,
},

.send_pkt = vhost_transport_send_pkt,
diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 3f9c16611306..c58453699ee9 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -245,4 +245,5 @@ u32 virtio_transport_get_credit(struct virtio_vsock_sock *vvs, u32 wanted);
void virtio_transport_put_credit(struct virtio_vsock_sock *vvs, u32 credit);
void virtio_transport_deliver_tap_pkt(struct sk_buff *skb);
int virtio_transport_purge_skbs(void *vsk, struct sk_buff_head *list);
+int virtio_transport_read_skb(struct vsock_sock *vsk, skb_read_actor_t read_actor);
#endif /* _LINUX_VIRTIO_VSOCK_H */
diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index 568a87c5e0d0..a73f5fbd296a 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -75,6 +75,7 @@ struct vsock_sock {
void *trans;
};

+s64 vsock_connectible_has_data(struct vsock_sock *vsk);
s64 vsock_stream_has_data(struct vsock_sock *vsk);
s64 vsock_stream_has_space(struct vsock_sock *vsk);
struct sock *vsock_create_connected(struct sock *parent);
@@ -173,6 +174,9 @@ struct vsock_transport {

/* Addressing. */
u32 (*get_local_cid)(void);
+
+ /* Read a single skb */
+ int (*read_skb)(struct vsock_sock *, skb_read_actor_t);
};

/**** CORE ****/
@@ -225,5 +229,18 @@ int vsock_init_tap(void);
int vsock_add_tap(struct vsock_tap *vt);
int vsock_remove_tap(struct vsock_tap *vt);
void vsock_deliver_tap(struct sk_buff *build_skb(void *opaque), void *opaque);
+int vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
+ int flags);
+int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
+ size_t len, int flags);
+
+#ifdef CONFIG_BPF_SYSCALL
+extern struct proto vsock_proto;
+int vsock_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
+void __init vsock_bpf_build_proto(void);
+#else
+static inline void __init vsock_bpf_build_proto(void)
+{}
+#endif

#endif /* __AF_VSOCK_H__ */
diff --git a/net/vmw_vsock/Makefile b/net/vmw_vsock/Makefile
index 6a943ec95c4a..5da74c4a9f1d 100644
--- a/net/vmw_vsock/Makefile
+++ b/net/vmw_vsock/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_HYPERV_VSOCKETS) += hv_sock.o
obj-$(CONFIG_VSOCKETS_LOOPBACK) += vsock_loopback.o

vsock-y += af_vsock.o af_vsock_tap.o vsock_addr.o
+vsock-$(CONFIG_BPF_SYSCALL) += vsock_bpf.o

vsock_diag-y += diag.o

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 19aea7cba26e..f2cc04fb8b13 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -116,10 +116,13 @@ static void vsock_sk_destruct(struct sock *sk);
static int vsock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);

/* Protocol family. */
-static struct proto vsock_proto = {
+struct proto vsock_proto = {
.name = "AF_VSOCK",
.owner = THIS_MODULE,
.obj_size = sizeof(struct vsock_sock),
+#ifdef CONFIG_BPF_SYSCALL
+ .psock_update_sk_prot = vsock_bpf_update_proto,
+#endif
};

/* The default peer timeout indicates how long we will wait for a peer response
@@ -865,7 +868,7 @@ s64 vsock_stream_has_data(struct vsock_sock *vsk)
}
EXPORT_SYMBOL_GPL(vsock_stream_has_data);

-static s64 vsock_connectible_has_data(struct vsock_sock *vsk)
+s64 vsock_connectible_has_data(struct vsock_sock *vsk)
{
struct sock *sk = sk_vsock(vsk);

@@ -874,6 +877,7 @@ static s64 vsock_connectible_has_data(struct vsock_sock *vsk)
else
return vsock_stream_has_data(vsk);
}
+EXPORT_SYMBOL_GPL(vsock_connectible_has_data);

s64 vsock_stream_has_space(struct vsock_sock *vsk)
{
@@ -1131,6 +1135,13 @@ static __poll_t vsock_poll(struct file *file, struct socket *sock,
return mask;
}

+static int vsock_read_skb(struct sock *sk, skb_read_actor_t read_actor)
+{
+ struct vsock_sock *vsk = vsock_sk(sk);
+
+ return vsk->transport->read_skb(vsk, read_actor);
+}
+
static int vsock_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
size_t len)
{
@@ -1241,19 +1252,34 @@ static int vsock_dgram_connect(struct socket *sock,

memcpy(&vsk->remote_addr, remote_addr, sizeof(vsk->remote_addr));
sock->state = SS_CONNECTED;
+ sk->sk_state = TCP_ESTABLISHED;

out:
release_sock(sk);
return err;
}

-static int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
- size_t len, int flags)
+int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
+ size_t len, int flags)
{
- struct vsock_sock *vsk = vsock_sk(sock->sk);
+#ifdef CONFIG_BPF_SYSCALL
+ const struct proto *prot;
+#endif
+ struct vsock_sock *vsk;
+ struct sock *sk;
+
+ sk = sock->sk;
+ vsk = vsock_sk(sk);
+
+#ifdef CONFIG_BPF_SYSCALL
+ prot = READ_ONCE(sk->sk_prot);
+ if (prot != &vsock_proto)
+ return prot->recvmsg(sk, msg, len, flags, NULL);
+#endif

return vsk->transport->dgram_dequeue(vsk, msg, len, flags);
}
+EXPORT_SYMBOL_GPL(vsock_dgram_recvmsg);

static const struct proto_ops vsock_dgram_ops = {
.family = PF_VSOCK,
@@ -1272,6 +1298,7 @@ static const struct proto_ops vsock_dgram_ops = {
.recvmsg = vsock_dgram_recvmsg,
.mmap = sock_no_mmap,
.sendpage = sock_no_sendpage,
+ .read_skb = vsock_read_skb,
};

static int vsock_transport_cancel_pkt(struct vsock_sock *vsk)
@@ -2086,13 +2113,16 @@ static int __vsock_seqpacket_recvmsg(struct sock *sk, struct msghdr *msg,
return err;
}

-static int
+int
vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
int flags)
{
struct sock *sk;
struct vsock_sock *vsk;
const struct vsock_transport *transport;
+#ifdef CONFIG_BPF_SYSCALL
+ const struct proto *prot;
+#endif
int err;

sk = sock->sk;
@@ -2139,6 +2169,14 @@ vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
goto out;
}

+#ifdef CONFIG_BPF_SYSCALL
+ prot = READ_ONCE(sk->sk_prot);
+ if (prot != &vsock_proto) {
+ release_sock(sk);
+ return prot->recvmsg(sk, msg, len, flags, NULL);
+ }
+#endif
+
if (sk->sk_type == SOCK_STREAM)
err = __vsock_stream_recvmsg(sk, msg, len, flags);
else
@@ -2148,6 +2186,7 @@ vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
release_sock(sk);
return err;
}
+EXPORT_SYMBOL_GPL(vsock_connectible_recvmsg);

static int vsock_set_rcvlowat(struct sock *sk, int val)
{
@@ -2188,6 +2227,7 @@ static const struct proto_ops vsock_stream_ops = {
.mmap = sock_no_mmap,
.sendpage = sock_no_sendpage,
.set_rcvlowat = vsock_set_rcvlowat,
+ .read_skb = vsock_read_skb,
};

static const struct proto_ops vsock_seqpacket_ops = {
@@ -2209,6 +2249,7 @@ static const struct proto_ops vsock_seqpacket_ops = {
.recvmsg = vsock_connectible_recvmsg,
.mmap = sock_no_mmap,
.sendpage = sock_no_sendpage,
+ .read_skb = vsock_read_skb,
};

static int vsock_create(struct net *net, struct socket *sock,
@@ -2348,6 +2389,8 @@ static int __init vsock_init(void)
goto err_unregister_proto;
}

+ vsock_bpf_build_proto();
+
return 0;

err_unregister_proto:
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index 28b5a8e8e094..e95df847176b 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -457,6 +457,8 @@ static struct virtio_transport virtio_transport = {
.notify_send_pre_enqueue = virtio_transport_notify_send_pre_enqueue,
.notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
.notify_buffer_size = virtio_transport_notify_buffer_size,
+
+ .read_skb = virtio_transport_read_skb,
},

.send_pkt = virtio_transport_send_pkt,
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index a1581c77cf84..82bdaf61ee02 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -1388,6 +1388,30 @@ int virtio_transport_purge_skbs(void *vsk, struct sk_buff_head *queue)
}
EXPORT_SYMBOL_GPL(virtio_transport_purge_skbs);

+int virtio_transport_read_skb(struct vsock_sock *vsk, skb_read_actor_t recv_actor)
+{
+ struct virtio_vsock_sock *vvs = vsk->trans;
+ struct sock *sk = sk_vsock(vsk);
+ struct sk_buff *skb;
+ int off = 0;
+ int copied;
+ int err;
+
+ spin_lock_bh(&vvs->rx_lock);
+ /* Use __skb_recv_datagram() for race-free handling of the receive. It
+ * works for types other than dgrams. */
+ skb = __skb_recv_datagram(sk, &vvs->rx_queue, MSG_DONTWAIT, &off, &err);
+ spin_unlock_bh(&vvs->rx_lock);
+
+ if (!skb)
+ return err;
+
+ copied = recv_actor(sk, skb);
+ kfree_skb(skb);
+ return copied;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_read_skb);
+
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Asias He");
MODULE_DESCRIPTION("common code for virtio vsock");
diff --git a/net/vmw_vsock/vsock_bpf.c b/net/vmw_vsock/vsock_bpf.c
new file mode 100644
index 000000000000..ee92a1f42031
--- /dev/null
+++ b/net/vmw_vsock/vsock_bpf.c
@@ -0,0 +1,175 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Bobby Eshleman <bobby.eshleman@xxxxxxxxxxxxx>
+ *
+ * Based off of net/unix/unix_bpf.c
+ */
+
+#include <linux/bpf.h>
+#include <linux/module.h>
+#include <linux/skmsg.h>
+#include <linux/socket.h>
+#include <linux/wait.h>
+#include <net/af_vsock.h>
+#include <net/sock.h>
+
+#define vsock_sk_has_data(__sk, __psock) \
+ ({ !skb_queue_empty(&__sk->sk_receive_queue) || \
+ !skb_queue_empty(&__psock->ingress_skb) || \
+ !list_empty(&__psock->ingress_msg); \
+ })
+
+static struct proto *vsock_prot_saved __read_mostly;
+static DEFINE_SPINLOCK(vsock_prot_lock);
+static struct proto vsock_bpf_prot;
+
+static bool vsock_has_data(struct sock *sk, struct sk_psock *psock)
+{
+ struct vsock_sock *vsk = vsock_sk(sk);
+ s64 ret;
+
+ ret = vsock_connectible_has_data(vsk);
+ if (ret > 0)
+ return true;
+
+ return vsock_sk_has_data(sk, psock);
+}
+
+static int vsock_msg_wait_data(struct sock *sk, struct sk_psock *psock, long timeo)
+{
+ int ret = 0;
+
+ DEFINE_WAIT_FUNC(wait, woken_wake_function);
+
+ if (sk->sk_shutdown & RCV_SHUTDOWN)
+ return 1;
+
+ if (!timeo)
+ return ret;
+
+ add_wait_queue(sk_sleep(sk), &wait);
+ sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+ ret = vsock_has_data(sk, psock);
+ if (!ret) {
+ wait_woken(&wait, TASK_INTERRUPTIBLE, timeo);
+ ret = vsock_has_data(sk, psock);
+ }
+ sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+ remove_wait_queue(sk_sleep(sk), &wait);
+ return ret;
+}
+
+static int __vsock_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int flags)
+{
+ struct socket *sock = sk->sk_socket;
+ int err;
+
+ if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET)
+ err = vsock_connectible_recvmsg(sock, msg, len, flags);
+ else if (sk->sk_type == SOCK_DGRAM)
+ err = vsock_dgram_recvmsg(sock, msg, len, flags);
+ else
+ err = -EPROTOTYPE;
+
+ return err;
+}
+
+static int vsock_bpf_recvmsg(struct sock *sk, struct msghdr *msg,
+ size_t len, int flags, int *addr_len)
+{
+ struct sk_psock *psock;
+ int copied;
+
+ psock = sk_psock_get(sk);
+ lock_sock(sk);
+ if (unlikely(!psock)) {
+ release_sock(sk);
+ return __vsock_recvmsg(sk, msg, len, flags);
+ }
+
+ if (vsock_has_data(sk, psock) && sk_psock_queue_empty(psock)) {
+ release_sock(sk);
+ sk_psock_put(sk, psock);
+ return __vsock_recvmsg(sk, msg, len, flags);
+ }
+
+msg_bytes_ready:
+ copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
+ if (!copied) {
+ long timeo;
+ int data;
+
+ timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
+ data = vsock_msg_wait_data(sk, psock, timeo);
+ if (data) {
+ if (!sk_psock_queue_empty(psock))
+ goto msg_bytes_ready;
+ release_sock(sk);
+ sk_psock_put(sk, psock);
+ return __vsock_recvmsg(sk, msg, len, flags);
+ }
+ copied = -EAGAIN;
+ }
+ release_sock(sk);
+ sk_psock_put(sk, psock);
+
+ return copied;
+}
+
+/* Copy of original proto with updated sock_map methods */
+static struct proto vsock_bpf_prot = {
+ .close = sock_map_close,
+ .recvmsg = vsock_bpf_recvmsg,
+ .sock_is_readable = sk_msg_is_readable,
+ .unhash = sock_map_unhash,
+};
+
+static void vsock_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
+{
+ *prot = *base;
+ prot->close = sock_map_close;
+ prot->recvmsg = vsock_bpf_recvmsg;
+ prot->sock_is_readable = sk_msg_is_readable;
+}
+
+static void vsock_bpf_check_needs_rebuild(struct proto *ops)
+{
+ /* Paired with the smp_store_release() below. */
+ if (unlikely(ops != smp_load_acquire(&vsock_prot_saved))) {
+ spin_lock_bh(&vsock_prot_lock);
+ if (likely(ops != vsock_prot_saved)) {
+ vsock_bpf_rebuild_protos(&vsock_bpf_prot, ops);
+ /* Make sure proto function pointers are updated before publishing the
+ * pointer to the struct.
+ */
+ smp_store_release(&vsock_prot_saved, ops);
+ }
+ spin_unlock_bh(&vsock_prot_lock);
+ }
+}
+
+int vsock_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
+{
+ struct vsock_sock *vsk;
+
+ if (restore) {
+ sk->sk_write_space = psock->saved_write_space;
+ sock_replace_proto(sk, psock->sk_proto);
+ return 0;
+ }
+
+ vsk = vsock_sk(sk);
+ if (!vsk->transport)
+ return -ENODEV;
+
+ if (!vsk->transport->read_skb)
+ return -EOPNOTSUPP;
+
+ vsock_bpf_check_needs_rebuild(psock->sk_proto);
+ sock_replace_proto(sk, &vsock_bpf_prot);
+ return 0;
+}
+
+void __init vsock_bpf_build_proto(void)
+{
+ vsock_bpf_rebuild_protos(&vsock_bpf_prot, &vsock_proto);
+}
diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c
index 671e03240fc5..40753b661c13 100644
--- a/net/vmw_vsock/vsock_loopback.c
+++ b/net/vmw_vsock/vsock_loopback.c
@@ -94,6 +94,8 @@ static struct virtio_transport loopback_transport = {
.notify_send_pre_enqueue = virtio_transport_notify_send_pre_enqueue,
.notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
.notify_buffer_size = virtio_transport_notify_buffer_size,
+
+ .read_skb = virtio_transport_read_skb,
},

.send_pkt = vsock_loopback_send_pkt,

--
2.35.1

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