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

On Mon, Jan 30, 2023 at 08:35:12PM -0800, Bobby Eshleman wrote:

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@bytedance.com

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);
  

checkpatch complains: "CHECK: Alignment should match open parenthesis"

+#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. */
  

Checkpatch: WARNING: Block comments use a trailing */ on a separate line

Since we also use this convention in the other comments in this file, I would follow it.

• 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@bytedance.com

• • 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);		\
  

• })
  

Some suggestions from checkpatch that I would fix:

CHECK: Macro argument '__sk' may be better as '(__sk)' to avoid precedence issues CHECK: Macro argument '__psock' may be better as '(__psock)' to avoid precedence issues

+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)

IIUC now this function returns 0 when there isn't data and 1 when there is data, maybe better to change the return type to bool.

+{

• 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);
  

I'm not sure we need the lock to check psock, so can we move this block before the lock_sock?

• 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:

I saw that this code is also in unix_bpf.c and tcp_bpf.c, so I guess it's acceptable, but I would have avoided using a label to go back. I prefer a to use goto only for centralized exiting of functions.

One possible refactoring (not tested):

copied = sk_msg_recvmsg(sk, psock, msg, len, flags); while (!copied) { long timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);

if (!vsock_msg_wait_data(sk, psock, timeo)) { copied = -EAGAIN; break; }

if (sk_psock_queue_empty(psock)) { release_sock(sk); sk_psock_put(sk, psock); return __vsock_recvmsg(sk, msg, len, flags); }

copied = sk_msg_recvmsg(sk, psock, msg, len, flags); } ...

I'm not sure why we need to call release_sock() and sk_psock_put() before __vsock_recvmsg(). If it is not needed we can simplify more the previous code.

The rest LGTM.

Thanks, Stefano

• 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