diff mbox series

[v2,mptcp-next,5/5] mptcp: add netlink event support

Message ID 20210120154337.27997-6-fw@strlen.de
State Accepted, archived
Commit f15cd5fd4c2695150e4c3269f35c189fd0c06a8d
Delegated to: Matthieu Baerts
Headers show
Series mptcp: netlink event support | expand

Commit Message

Florian Westphal Jan. 20, 2021, 3:43 p.m. UTC 
Allow userspace (mptcpd) to subscribe to mptcp genl multicast events.
This implementation reuses the same event API as the mptcp kernel fork
to ease integration of existing tools, e.g. mptcpd.

Supported events include:
1. start and close of an mptcp connection
2. start and close of subflows (joins)
3. announce and withdrawals of addresses
4. subflow priority (backup/non-backup) change.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 include/uapi/linux/mptcp.h |  73 +++++++++++
 net/mptcp/pm.c             |  20 ++-
 net/mptcp/pm_netlink.c     | 261 ++++++++++++++++++++++++++++++++++++-
 net/mptcp/protocol.c       |   9 +-
 net/mptcp/protocol.h       |   6 +
 5 files changed, 362 insertions(+), 7 deletions(-)

Comments

Matthieu Baerts Jan. 20, 2021, 5:15 p.m. UTC | #1 
Hi Florian,

On 20/01/2021 16:43, Florian Westphal wrote:
> Allow userspace (mptcpd) to subscribe to mptcp genl multicast events.
> This implementation reuses the same event API as the mptcp kernel fork
> to ease integration of existing tools, e.g. mptcpd.
> 
> Supported events include:
> 1. start and close of an mptcp connection
> 2. start and close of subflows (joins)
> 3. announce and withdrawals of addresses
> 4. subflow priority (backup/non-backup) change.
> 
> Signed-off-by: Florian Westphal <fw@strlen.de>

Thank you for the v2!

(...)

 > diff --git a/include/uapi/linux/mptcp.h b/include/uapi/linux/mptcp.h
 > index 3674a451a18c..4983ced8e1f8 100644
 > --- a/include/uapi/linux/mptcp.h
 > +++ b/include/uapi/linux/mptcp.h
 > @@ -36,6 +36,7 @@ enum {
 >   /* netlink interface */
 >   #define MPTCP_PM_NAME		"mptcp_pm"
 >   #define MPTCP_PM_CMD_GRP_NAME	"mptcp_pm_cmds"
 > +#define MPTCP_PM_EV_GRP_NAME    "mptcp_events"

We will check if it is OK for Ossama :)

(...)

> diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
> index e2f40985b450..c2939362f47a 100644
> --- a/net/mptcp/pm_netlink.c
> +++ b/net/mptcp/pm_netlink.c

(...)

> +static int mptcp_event_put_token_and_ssk(struct sk_buff *skb,
> +					 const struct mptcp_sock *msk,
> +					 const struct sock *ssk)
> +{
> +	const struct sock *sk = (const struct sock *)msk;
> +	const struct mptcp_subflow_context *sf;
> +	u8 sk_err;
> +
> +	if (nla_put_u32(skb, MPTCP_ATTR_TOKEN, msk->token))
> +		return -EMSGSIZE;
> +
> +	if (mptcp_event_add_subflow(skb, ssk))
> +		return -EMSGSIZE;
> +
> +	sf = mptcp_subflow_ctx(ssk);
> +	if (WARN_ON_ONCE(!sf))
> +		return -EINVAL;
> +
> +	if (nla_put_u8(skb, MPTCP_ATTR_BACKUP, sf->backup))
> +		return -EMSGSIZE;
> +
> +	if (ssk->sk_bound_dev_if &&
> +	    nla_put_s32(skb, MPTCP_ATTR_IF_IDX, ssk->sk_bound_dev_if))
> +		return -EMSGSIZE;
> +
> +	sk_err = ssk->sk_err;

Could we have an error set on the msk? (sk->sk_err)
I don't remember why but in mptcp.org, we take the one of the subflow if 
there is one and we fallback to the sk_err of the meta. But I don't 
remember in which case we can have sk_err set on the meta. And not sure 
if we can have one in the msk :)

It seems that we look for sk_err only in the ssk (subflow.c) and in 
mptcp_recvmsg() but maybe just because this code is an adaptation of the 
one from TCP?

> +	if (sk_err && sk->sk_state == TCP_ESTABLISHED &&
> +	    nla_put_u8(skb, MPTCP_ATTR_ERROR, sk_err))
> +		return -EMSGSIZE;
> +
> +	return 0;
> +}

Thank you for the other modifications!

Cheers,
Matt
Florian Westphal Jan. 20, 2021, 5:19 p.m. UTC | #2 
Matthieu Baerts <matthieu.baerts@tessares.net> wrote:
> > +	sk_err = ssk->sk_err;
> 
> Could we have an error set on the msk? (sk->sk_err)

Userspace interacts with the msk so it should already
get proper errnos via syscalls, no?
Matthieu Baerts Jan. 20, 2021, 5:23 p.m. UTC | #3 
On 20/01/2021 18:19, Florian Westphal wrote:
> Matthieu Baerts <matthieu.baerts@tessares.net> wrote:
>>> +	sk_err = ssk->sk_err;
>>
>> Could we have an error set on the msk? (sk->sk_err)
> 
> Userspace interacts with the msk so it should already
> get proper errnos via syscalls, no?

I think likely the module (e.g. mptcpd) interacting with this in-kernel 
Netlink PM is not the one which initiated the connection (msk).

On the other hand, we also check that the msk is still in established 
mode. What kind of error could we have?

In mptcp.org, we might have taken the one from the meta "just in case".

Cheers,
Matt
Matthieu Baerts Jan. 22, 2021, 10:55 a.m. UTC | #4 
Hi Florian,

On 20/01/2021 18:15, Matthieu Baerts wrote:
> On 20/01/2021 16:43, Florian Westphal wrote:
> 
>  > diff --git a/include/uapi/linux/mptcp.h b/include/uapi/linux/mptcp.h
>  > index 3674a451a18c..4983ced8e1f8 100644
>  > --- a/include/uapi/linux/mptcp.h
>  > +++ b/include/uapi/linux/mptcp.h
>  > @@ -36,6 +36,7 @@ enum {
>  >   /* netlink interface */
>  >   #define MPTCP_PM_NAME        "mptcp_pm"
>  >   #define MPTCP_PM_CMD_GRP_NAME    "mptcp_pm_cmds"
>  > +#define MPTCP_PM_EV_GRP_NAME    "mptcp_events"
> 
> We will check if it is OK for Ossama :)

Just to be sure it is clear for everyone, it was decided yesterday at 
the weekly meeting to switch to "mptcp_pm_events".

>> diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
>> index e2f40985b450..c2939362f47a 100644
>> --- a/net/mptcp/pm_netlink.c
>> +++ b/net/mptcp/pm_netlink.c
> 
> (...)
> 
>> +static int mptcp_event_put_token_and_ssk(struct sk_buff *skb,
>> +                     const struct mptcp_sock *msk,
>> +                     const struct sock *ssk)
>> +{
>> +    const struct sock *sk = (const struct sock *)msk;
>> +    const struct mptcp_subflow_context *sf;
>> +    u8 sk_err;
>> +
>> +    if (nla_put_u32(skb, MPTCP_ATTR_TOKEN, msk->token))
>> +        return -EMSGSIZE;
>> +
>> +    if (mptcp_event_add_subflow(skb, ssk))
>> +        return -EMSGSIZE;
>> +
>> +    sf = mptcp_subflow_ctx(ssk);
>> +    if (WARN_ON_ONCE(!sf))
>> +        return -EINVAL;
>> +
>> +    if (nla_put_u8(skb, MPTCP_ATTR_BACKUP, sf->backup))
>> +        return -EMSGSIZE;
>> +
>> +    if (ssk->sk_bound_dev_if &&
>> +        nla_put_s32(skb, MPTCP_ATTR_IF_IDX, ssk->sk_bound_dev_if))
>> +        return -EMSGSIZE;
>> +
>> +    sk_err = ssk->sk_err;
> 
> Could we have an error set on the msk? (sk->sk_err)

And here, as discussed yesterday, we would keep "ssk->sk_err" and not 
use the one from the msk.

I guess Mat and Ossama prefer to quickly validate it before applying 
these patches, I can wait before applying them. Or maybe I misunderstood 
and I can apply it sooner.
(And if we only need to change the group name, I can fix that when 
applying it without having to submit a new version ;-) )

For this patch:

Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>

Cheers,
Matt
Florian Westphal Jan. 26, 2021, 3:04 p.m. UTC | #5 
Matthieu Baerts <matthieu.baerts@tessares.net> wrote:
> I guess Mat and Ossama prefer to quickly validate it before applying these
> patches, I can wait before applying them. Or maybe I misunderstood and I can
> apply it sooner.
> (And if we only need to change the group name, I can fix that when applying
> it without having to submit a new version ;-) )

Thanks, let me know if there are rejects and I can repost.
Mat Martineau Jan. 26, 2021, 4:51 p.m. UTC | #6 
On Fri, 22 Jan 2021, Matthieu Baerts wrote:

> Hi Florian,
>
> On 20/01/2021 18:15, Matthieu Baerts wrote:
>> On 20/01/2021 16:43, Florian Westphal wrote:
>>
>>  > diff --git a/include/uapi/linux/mptcp.h b/include/uapi/linux/mptcp.h
>>  > index 3674a451a18c..4983ced8e1f8 100644
>>  > --- a/include/uapi/linux/mptcp.h
>>  > +++ b/include/uapi/linux/mptcp.h
>>  > @@ -36,6 +36,7 @@ enum {
>>  >   /* netlink interface */
>>  >   #define MPTCP_PM_NAME        "mptcp_pm"
>>  >   #define MPTCP_PM_CMD_GRP_NAME    "mptcp_pm_cmds"
>>  > +#define MPTCP_PM_EV_GRP_NAME    "mptcp_events"
>> 
>> We will check if it is OK for Ossama :)
>
> Just to be sure it is clear for everyone, it was decided yesterday at the 
> weekly meeting to switch to "mptcp_pm_events".
>
>>> diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
>>> index e2f40985b450..c2939362f47a 100644
>>> --- a/net/mptcp/pm_netlink.c
>>> +++ b/net/mptcp/pm_netlink.c
>> 
>> (...)
>> 
>>> +static int mptcp_event_put_token_and_ssk(struct sk_buff *skb,
>>> +                     const struct mptcp_sock *msk,
>>> +                     const struct sock *ssk)
>>> +{
>>> +    const struct sock *sk = (const struct sock *)msk;
>>> +    const struct mptcp_subflow_context *sf;
>>> +    u8 sk_err;
>>> +
>>> +    if (nla_put_u32(skb, MPTCP_ATTR_TOKEN, msk->token))
>>> +        return -EMSGSIZE;
>>> +
>>> +    if (mptcp_event_add_subflow(skb, ssk))
>>> +        return -EMSGSIZE;
>>> +
>>> +    sf = mptcp_subflow_ctx(ssk);
>>> +    if (WARN_ON_ONCE(!sf))
>>> +        return -EINVAL;
>>> +
>>> +    if (nla_put_u8(skb, MPTCP_ATTR_BACKUP, sf->backup))
>>> +        return -EMSGSIZE;
>>> +
>>> +    if (ssk->sk_bound_dev_if &&
>>> +        nla_put_s32(skb, MPTCP_ATTR_IF_IDX, ssk->sk_bound_dev_if))
>>> +        return -EMSGSIZE;
>>> +
>>> +    sk_err = ssk->sk_err;
>> 
>> Could we have an error set on the msk? (sk->sk_err)
>
> And here, as discussed yesterday, we would keep "ssk->sk_err" and not use the 
> one from the msk.
>
> I guess Mat and Ossama prefer to quickly validate it before applying these 
> patches, I can wait before applying them. Or maybe I misunderstood and I can 
> apply it sooner.
> (And if we only need to change the group name, I can fix that when applying 
> it without having to submit a new version ;-) )
>

Hi Matthieu -

Go ahead and apply the series to the export branch with the group name 
fix, if other fixes are needed after testing we can squash those.

Thanks,

--
Mat Martineau
Intel
diff mbox series

Patch

diff --git a/include/uapi/linux/mptcp.h b/include/uapi/linux/mptcp.h
index 3674a451a18c..4983ced8e1f8 100644
--- a/include/uapi/linux/mptcp.h
+++ b/include/uapi/linux/mptcp.h
@@ -36,6 +36,7 @@  enum {
 /* netlink interface */
 #define MPTCP_PM_NAME		"mptcp_pm"
 #define MPTCP_PM_CMD_GRP_NAME	"mptcp_pm_cmds"
+#define MPTCP_PM_EV_GRP_NAME    "mptcp_events"
 #define MPTCP_PM_VER		0x1
 
 /*
@@ -104,4 +105,76 @@  struct mptcp_info {
 	__u64	mptcpi_rcv_nxt;
 };
 
+/*
+ * MPTCP_EVENT_CREATED: token, family, saddr4 | saddr6, daddr4 | daddr6,
+ *                      sport, dport
+ * A new MPTCP connection has been created. It is the good time to allocate
+ * memory and send ADD_ADDR if needed. Depending on the traffic-patterns
+ * it can take a long time until the MPTCP_EVENT_ESTABLISHED is sent.
+ *
+ * MPTCP_EVENT_ESTABLISHED: token, family, saddr4 | saddr6, daddr4 | daddr6,
+ *			    sport, dport
+ * A MPTCP connection is established (can start new subflows).
+ *
+ * MPTCP_EVENT_CLOSED: token
+ * A MPTCP connection has stopped.
+ *
+ * MPTCP_EVENT_ANNOUNCED: token, rem_id, family, daddr4 | daddr6 [, dport]
+ * A new address has been announced by the peer.
+ *
+ * MPTCP_EVENT_REMOVED: token, rem_id
+ * An address has been lost by the peer.
+ *
+ * MPTCP_EVENT_SUB_ESTABLISHED: token, family, saddr4 | saddr6,
+ *                              daddr4 | daddr6, sport, dport, backup,
+ *                              if_idx [, error]
+ * A new subflow has been established. 'error' should not be set.
+ *
+ * MPTCP_EVENT_SUB_CLOSED: token, family, saddr4 | saddr6, daddr4 | daddr6,
+ *                         sport, dport, backup, if_idx [, error]
+ * A subflow has been closed. An error (copy of sk_err) could be set if an
+ * error has been detected for this subflow.
+ *
+ * MPTCP_EVENT_SUB_PRIORITY: token, family, saddr4 | saddr6, daddr4 | daddr6,
+ *                           sport, dport, backup, if_idx [, error]
+ *       The priority of a subflow has changed. 'error' should not be set.
+ */
+enum mptcp_event_type {
+	MPTCP_EVENT_UNSPEC = 0,
+	MPTCP_EVENT_CREATED = 1,
+	MPTCP_EVENT_ESTABLISHED = 2,
+	MPTCP_EVENT_CLOSED = 3,
+
+	MPTCP_EVENT_ANNOUNCED = 6,
+	MPTCP_EVENT_REMOVED = 7,
+
+	MPTCP_EVENT_SUB_ESTABLISHED = 10,
+	MPTCP_EVENT_SUB_CLOSED = 11,
+
+	MPTCP_EVENT_SUB_PRIORITY = 13,
+};
+
+enum mptcp_event_attr {
+	MPTCP_ATTR_UNSPEC = 0,
+
+	MPTCP_ATTR_TOKEN,	/* u32 */
+	MPTCP_ATTR_FAMILY,	/* u16 */
+	MPTCP_ATTR_LOC_ID,	/* u8 */
+	MPTCP_ATTR_REM_ID,	/* u8 */
+	MPTCP_ATTR_SADDR4,	/* be32 */
+	MPTCP_ATTR_SADDR6,	/* struct in6_addr */
+	MPTCP_ATTR_DADDR4,	/* be32 */
+	MPTCP_ATTR_DADDR6,	/* struct in6_addr */
+	MPTCP_ATTR_SPORT,	/* be16 */
+	MPTCP_ATTR_DPORT,	/* be16 */
+	MPTCP_ATTR_BACKUP,	/* u8 */
+	MPTCP_ATTR_ERROR,	/* u8 */
+	MPTCP_ATTR_FLAGS,	/* u16 */
+	MPTCP_ATTR_TIMEOUT,	/* u32 */
+	MPTCP_ATTR_IF_IDX,	/* s32 */
+
+	__MPTCP_ATTR_AFTER_LAST
+};
+#define MPTCP_ATTR_MAX (__MPTCP_ATTR_AFTER_LAST - 1)
+
 #endif /* _UAPI_MPTCP_H */
diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index b3f53432b3ea..3a09b6e32f8f 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -75,6 +75,7 @@  void mptcp_pm_new_connection(struct mptcp_sock *msk, const struct sock *ssk, int
 	pr_debug("msk=%p, token=%u side=%d", msk, msk->token, server_side);
 
 	WRITE_ONCE(pm->server_side, server_side);
+	mptcp_event(MPTCP_EVENT_CREATED, msk, ssk, GFP_ATOMIC);
 }
 
 bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk)
@@ -122,13 +123,10 @@  static bool mptcp_pm_schedule_work(struct mptcp_sock *msk,
 void mptcp_pm_fully_established(struct mptcp_sock *msk, const struct sock *ssk, gfp_t gfp)
 {
 	struct mptcp_pm_data *pm = &msk->pm;
+	bool announce = false;
 
 	pr_debug("msk=%p", msk);
 
-	/* try to avoid acquiring the lock below */
-	if (!READ_ONCE(pm->work_pending))
-		return;
-
 	spin_lock_bh(&pm->lock);
 
 	/* mptcp_pm_fully_established() can be invoked by multiple
@@ -138,9 +136,15 @@  void mptcp_pm_fully_established(struct mptcp_sock *msk, const struct sock *ssk,
 	if (READ_ONCE(pm->work_pending) &&
 	    !(msk->pm.status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)))
 		mptcp_pm_schedule_work(msk, MPTCP_PM_ESTABLISHED);
-	msk->pm.status |= BIT(MPTCP_PM_ALREADY_ESTABLISHED);
 
+	if ((msk->pm.status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)) == 0)
+		announce = true;
+
+	msk->pm.status |= BIT(MPTCP_PM_ALREADY_ESTABLISHED);
 	spin_unlock_bh(&pm->lock);
+
+	if (announce)
+		mptcp_event(MPTCP_EVENT_ESTABLISHED, msk, ssk, gfp);
 }
 
 void mptcp_pm_connection_closed(struct mptcp_sock *msk)
@@ -179,6 +183,8 @@  void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
 	pr_debug("msk=%p remote_id=%d accept=%d", msk, addr->id,
 		 READ_ONCE(pm->accept_addr));
 
+	mptcp_event_addr_announced(msk, addr);
+
 	spin_lock_bh(&pm->lock);
 
 	if (!READ_ONCE(pm->accept_addr)) {
@@ -206,6 +212,8 @@  void mptcp_pm_rm_addr_received(struct mptcp_sock *msk, u8 rm_id)
 
 	pr_debug("msk=%p remote_id=%d", msk, rm_id);
 
+	mptcp_event_addr_removed(msk, rm_id);
+
 	spin_lock_bh(&pm->lock);
 	mptcp_pm_schedule_work(msk, MPTCP_PM_RM_ADDR_RECEIVED);
 	pm->rm_id = rm_id;
@@ -218,6 +226,8 @@  void mptcp_pm_mp_prio_received(struct sock *sk, u8 bkup)
 
 	pr_debug("subflow->backup=%d, bkup=%d\n", subflow->backup, bkup);
 	subflow->backup = bkup;
+
+	mptcp_event(MPTCP_EVENT_SUB_PRIORITY, mptcp_sk(subflow->conn), sk, GFP_ATOMIC);
 }
 
 /* path manager helpers */
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index e2f40985b450..c2939362f47a 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -862,10 +862,14 @@  void mptcp_pm_nl_data_init(struct mptcp_sock *msk)
 	WRITE_ONCE(pm->accept_subflow, subflows);
 }
 
-#define MPTCP_PM_CMD_GRP_OFFSET	0
+#define MPTCP_PM_CMD_GRP_OFFSET       0
+#define MPTCP_PM_EV_GRP_OFFSET        1
 
 static const struct genl_multicast_group mptcp_pm_mcgrps[] = {
 	[MPTCP_PM_CMD_GRP_OFFSET]	= { .name = MPTCP_PM_CMD_GRP_NAME, },
+	[MPTCP_PM_EV_GRP_OFFSET]        = { .name = MPTCP_PM_EV_GRP_NAME,
+					    .flags = GENL_UNS_ADMIN_PERM,
+					  },
 };
 
 static const struct nla_policy
@@ -1484,6 +1488,261 @@  static int mptcp_nl_cmd_set_flags(struct sk_buff *skb, struct genl_info *info)
 	return 0;
 }
 
+static void mptcp_nl_mcast_send(struct net *net, struct sk_buff *nlskb, gfp_t gfp)
+{
+	genlmsg_multicast_netns(&mptcp_genl_family, net,
+				nlskb, 0, MPTCP_PM_EV_GRP_OFFSET, gfp);
+}
+
+static int mptcp_event_add_subflow(struct sk_buff *skb, const struct sock *ssk)
+{
+	const struct inet_sock *issk = inet_sk(ssk);
+	const struct mptcp_subflow_context *sf;
+
+	if (nla_put_u16(skb, MPTCP_ATTR_FAMILY, ssk->sk_family))
+		return -EMSGSIZE;
+
+	switch (ssk->sk_family) {
+	case AF_INET:
+		if (nla_put_in_addr(skb, MPTCP_ATTR_SADDR4, issk->inet_saddr))
+			return -EMSGSIZE;
+		if (nla_put_in_addr(skb, MPTCP_ATTR_DADDR4, issk->inet_daddr))
+			return -EMSGSIZE;
+		break;
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+	case AF_INET6: {
+		const struct ipv6_pinfo *np = inet6_sk(ssk);
+
+		if (nla_put_in6_addr(skb, MPTCP_ATTR_SADDR6, &np->saddr))
+			return -EMSGSIZE;
+		if (nla_put_in6_addr(skb, MPTCP_ATTR_DADDR6, &ssk->sk_v6_daddr))
+			return -EMSGSIZE;
+		break;
+	}
+#endif
+	default:
+		WARN_ON_ONCE(1);
+		return -EMSGSIZE;
+	}
+
+	if (nla_put_be16(skb, MPTCP_ATTR_SPORT, issk->inet_sport))
+		return -EMSGSIZE;
+	if (nla_put_be16(skb, MPTCP_ATTR_DPORT, issk->inet_dport))
+		return -EMSGSIZE;
+
+	sf = mptcp_subflow_ctx(ssk);
+	if (WARN_ON_ONCE(!sf))
+		return -EINVAL;
+
+	if (nla_put_u8(skb, MPTCP_ATTR_LOC_ID, sf->local_id))
+		return -EMSGSIZE;
+
+	if (nla_put_u8(skb, MPTCP_ATTR_REM_ID, sf->remote_id))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
+static int mptcp_event_put_token_and_ssk(struct sk_buff *skb,
+					 const struct mptcp_sock *msk,
+					 const struct sock *ssk)
+{
+	const struct sock *sk = (const struct sock *)msk;
+	const struct mptcp_subflow_context *sf;
+	u8 sk_err;
+
+	if (nla_put_u32(skb, MPTCP_ATTR_TOKEN, msk->token))
+		return -EMSGSIZE;
+
+	if (mptcp_event_add_subflow(skb, ssk))
+		return -EMSGSIZE;
+
+	sf = mptcp_subflow_ctx(ssk);
+	if (WARN_ON_ONCE(!sf))
+		return -EINVAL;
+
+	if (nla_put_u8(skb, MPTCP_ATTR_BACKUP, sf->backup))
+		return -EMSGSIZE;
+
+	if (ssk->sk_bound_dev_if &&
+	    nla_put_s32(skb, MPTCP_ATTR_IF_IDX, ssk->sk_bound_dev_if))
+		return -EMSGSIZE;
+
+	sk_err = ssk->sk_err;
+	if (sk_err && sk->sk_state == TCP_ESTABLISHED &&
+	    nla_put_u8(skb, MPTCP_ATTR_ERROR, sk_err))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
+static int mptcp_event_sub_established(struct sk_buff *skb,
+				       const struct mptcp_sock *msk,
+				       const struct sock *ssk)
+{
+	return mptcp_event_put_token_and_ssk(skb, msk, ssk);
+}
+
+static int mptcp_event_sub_closed(struct sk_buff *skb,
+				  const struct mptcp_sock *msk,
+				  const struct sock *ssk)
+{
+	if (mptcp_event_put_token_and_ssk(skb, msk, ssk))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
+static int mptcp_event_created(struct sk_buff *skb,
+			       const struct mptcp_sock *msk,
+			       const struct sock *ssk)
+{
+	int err = nla_put_u32(skb, MPTCP_ATTR_TOKEN, msk->token);
+
+	if (err)
+		return err;
+
+	return mptcp_event_add_subflow(skb, ssk);
+}
+
+void mptcp_event_addr_removed(const struct mptcp_sock *msk, uint8_t id)
+{
+	struct net *net = sock_net((const struct sock *)msk);
+	struct nlmsghdr *nlh;
+	struct sk_buff *skb;
+
+	if (!genl_has_listeners(&mptcp_genl_family, net, MPTCP_PM_EV_GRP_OFFSET))
+		return;
+
+	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
+	if (!skb)
+		return;
+
+	nlh = genlmsg_put(skb, 0, 0, &mptcp_genl_family, 0, MPTCP_EVENT_REMOVED);
+	if (!nlh)
+		goto nla_put_failure;
+
+	if (nla_put_u32(skb, MPTCP_ATTR_TOKEN, msk->token))
+		goto nla_put_failure;
+
+	if (nla_put_u8(skb, MPTCP_ATTR_REM_ID, id))
+		goto nla_put_failure;
+
+	genlmsg_end(skb, nlh);
+	mptcp_nl_mcast_send(net, skb, GFP_ATOMIC);
+	return;
+
+nla_put_failure:
+	kfree_skb(skb);
+}
+
+void mptcp_event_addr_announced(const struct mptcp_sock *msk,
+				const struct mptcp_addr_info *info)
+{
+	struct net *net = sock_net((const struct sock *)msk);
+	struct nlmsghdr *nlh;
+	struct sk_buff *skb;
+
+	if (!genl_has_listeners(&mptcp_genl_family, net, MPTCP_PM_EV_GRP_OFFSET))
+		return;
+
+	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
+	if (!skb)
+		return;
+
+	nlh = genlmsg_put(skb, 0, 0, &mptcp_genl_family, 0,
+			  MPTCP_EVENT_ANNOUNCED);
+	if (!nlh)
+		goto nla_put_failure;
+
+	if (nla_put_u32(skb, MPTCP_ATTR_TOKEN, msk->token))
+		goto nla_put_failure;
+
+	if (nla_put_u8(skb, MPTCP_ATTR_REM_ID, info->id))
+		goto nla_put_failure;
+
+	if (nla_put_be16(skb, MPTCP_ATTR_DPORT, info->port))
+		goto nla_put_failure;
+
+	switch (info->family) {
+	case AF_INET:
+		if (nla_put_in_addr(skb, MPTCP_ATTR_DADDR4, info->addr.s_addr))
+			goto nla_put_failure;
+		break;
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+	case AF_INET6:
+		if (nla_put_in6_addr(skb, MPTCP_ATTR_DADDR6, &info->addr6))
+			goto nla_put_failure;
+		break;
+#endif
+	default:
+		WARN_ON_ONCE(1);
+		goto nla_put_failure;
+	}
+
+	genlmsg_end(skb, nlh);
+	mptcp_nl_mcast_send(net, skb, GFP_ATOMIC);
+	return;
+
+nla_put_failure:
+	kfree_skb(skb);
+}
+
+void mptcp_event(enum mptcp_event_type type, const struct mptcp_sock *msk,
+		 const struct sock *ssk, gfp_t gfp)
+{
+	struct net *net = sock_net((const struct sock *)msk);
+	struct nlmsghdr *nlh;
+	struct sk_buff *skb;
+
+	if (!genl_has_listeners(&mptcp_genl_family, net, MPTCP_PM_EV_GRP_OFFSET))
+		return;
+
+	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, gfp);
+	if (!skb)
+		return;
+
+	nlh = genlmsg_put(skb, 0, 0, &mptcp_genl_family, 0, type);
+	if (!nlh)
+		goto nla_put_failure;
+
+	switch (type) {
+	case MPTCP_EVENT_UNSPEC:
+		WARN_ON_ONCE(1);
+		break;
+	case MPTCP_EVENT_CREATED:
+	case MPTCP_EVENT_ESTABLISHED:
+		if (mptcp_event_created(skb, msk, ssk) < 0)
+			goto nla_put_failure;
+		break;
+	case MPTCP_EVENT_CLOSED:
+		if (nla_put_u32(skb, MPTCP_ATTR_TOKEN, msk->token) < 0)
+			goto nla_put_failure;
+		break;
+	case MPTCP_EVENT_ANNOUNCED:
+	case MPTCP_EVENT_REMOVED:
+		/* call mptcp_event_addr_announced()/removed instead */
+		WARN_ON_ONCE(1);
+		break;
+	case MPTCP_EVENT_SUB_ESTABLISHED:
+	case MPTCP_EVENT_SUB_PRIORITY:
+		if (mptcp_event_sub_established(skb, msk, ssk) < 0)
+			goto nla_put_failure;
+		break;
+	case MPTCP_EVENT_SUB_CLOSED:
+		if (mptcp_event_sub_closed(skb, msk, ssk) < 0)
+			goto nla_put_failure;
+		break;
+	}
+
+	genlmsg_end(skb, nlh);
+	mptcp_nl_mcast_send(net, skb, gfp);
+	return;
+
+nla_put_failure:
+	kfree_skb(skb);
+}
+
 static const struct genl_small_ops mptcp_pm_ops[] = {
 	{
 		.cmd    = MPTCP_PM_CMD_ADD_ADDR,
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 3989135a2d9a..b5ba832ca58b 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2150,6 +2150,7 @@  static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 void mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 		     struct mptcp_subflow_context *subflow)
 {
+	mptcp_event(MPTCP_EVENT_SUB_CLOSED, mptcp_sk(sk), ssk, GFP_KERNEL);
 	__mptcp_close_ssk(sk, ssk, subflow);
 }
 
@@ -2586,6 +2587,10 @@  static void mptcp_close(struct sock *sk, long timeout)
 	release_sock(sk);
 	if (do_cancel_work)
 		mptcp_cancel_work(sk);
+
+	if (mptcp_sk(sk)->token)
+		mptcp_event(MPTCP_EVENT_CLOSED, mptcp_sk(sk), NULL, GFP_KERNEL);
+
 	sock_put(sk);
 }
 
@@ -3059,7 +3064,7 @@  bool mptcp_finish_join(struct sock *ssk)
 		return false;
 
 	if (!msk->pm.server_side)
-		return true;
+		goto out;
 
 	if (!mptcp_pm_allow_new_subflow(msk))
 		return false;
@@ -3086,6 +3091,8 @@  bool mptcp_finish_join(struct sock *ssk)
 	if (parent_sock && !ssk->sk_socket)
 		mptcp_sock_graft(ssk, parent_sock);
 	subflow->map_seq = READ_ONCE(msk->ack_seq);
+out:
+	mptcp_event(MPTCP_EVENT_SUB_ESTABLISHED, msk, ssk, GFP_ATOMIC);
 	return true;
 }
 
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index bf0b3d8d7146..447ce4631b43 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -10,6 +10,7 @@ 
 #include <linux/random.h>
 #include <net/tcp.h>
 #include <net/inet_connection_sock.h>
+#include <uapi/linux/mptcp.h>
 
 #define MPTCP_SUPPORTED_VERSION	1
 
@@ -665,6 +666,11 @@  int mptcp_pm_announce_addr(struct mptcp_sock *msk,
 int mptcp_pm_remove_addr(struct mptcp_sock *msk, u8 local_id);
 int mptcp_pm_remove_subflow(struct mptcp_sock *msk, u8 local_id);
 
+void mptcp_event(enum mptcp_event_type type, const struct mptcp_sock *msk,
+		 const struct sock *ssk, gfp_t gfp);
+void mptcp_event_addr_announced(const struct mptcp_sock *msk, const struct mptcp_addr_info *info);
+void mptcp_event_addr_removed(const struct mptcp_sock *msk, u8 id);
+
 static inline bool mptcp_pm_should_add_signal(struct mptcp_sock *msk)
 {
 	return READ_ONCE(msk->pm.addr_signal) & BIT(MPTCP_ADD_ADDR_SIGNAL);