mptcp: add subflow unique id
The user-space need to properly account the data received/sent by
individual subflows. When additional subflows are created and/or
closed during the MPTCP socket lifetime, the information currently
exposed via MPTCP_TCPINFO are not enough: subflows are identified only
by the sequential position inside the info dumps, and that will change
with the above mentioned events.
To solve the above problem, this patch introduces a new subflow
identifier that is unique inside the given MPTCP socket scope.
The initial subflow get the id 1 and the other subflows get incremental
values at join time.
Link: https://github.com/multipath-tcp/mptcp_net-next/issues/388
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index d5b8e48..4ebd6e9 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -96,6 +96,7 @@ static int __mptcp_socket_create(struct mptcp_sock *msk)
list_add(&subflow->node, &msk->conn_list);
sock_hold(ssock->sk);
subflow->request_mptcp = 1;
+ subflow->subflow_id = msk->subflow_id++;
/* This is the first subflow, always with id 0 */
subflow->local_id_valid = 1;
@@ -847,6 +848,7 @@ static bool __mptcp_finish_join(struct mptcp_sock *msk, struct sock *ssk)
if (sk->sk_socket && !ssk->sk_socket)
mptcp_sock_graft(ssk, sk->sk_socket);
+ mptcp_subflow_ctx(ssk)->subflow_id = msk->subflow_id++;
mptcp_sockopt_sync_locked(msk, ssk);
mptcp_subflow_joined(msk, ssk);
return true;
@@ -2732,6 +2734,7 @@ static int __mptcp_init_sock(struct sock *sk)
WRITE_ONCE(msk->csum_enabled, mptcp_is_checksum_enabled(sock_net(sk)));
WRITE_ONCE(msk->allow_infinite_fallback, true);
msk->recovery = false;
+ msk->subflow_id = 1;
mptcp_pm_data_init(msk);
@@ -3160,6 +3163,9 @@ struct sock *mptcp_sk_clone_init(const struct sock *sk,
msk->wnd_end = msk->snd_nxt + req->rsk_rcv_wnd;
msk->setsockopt_seq = mptcp_sk(sk)->setsockopt_seq;
+ /* passive msk is created after the first/MPC subflow */
+ msk->subflow_id = 2;
+
sock_reset_flag(nsk, SOCK_RCU_FREE);
security_inet_csk_clone(nsk, req);
