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

On Thu, Feb 16, 2023 at 11:11:10AM +0100, Stefano Garzarella wrote:

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

Thanks Stefano, I'll incorporate your feedback in the next rev and remove the RFC header as suggested.

Thanks again, hope you had a good time off work!

Best, Bobby

...

• 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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