[PATCH mptcp-next v5 03/11] mptcp: inherit sk_reuse/sk_reuseport and fix dev bind override

From: Geliang Tang <[email protected]>

Propagate sk_reuse and sk_reuseport from master socket to subflows, and
bump setsockopt_seq so later subflows pick up the changes.

This patch also fixes unconditional sk_bound_dev_if override in
__mptcp_subflow_connect(): only set it when local->ifindex is non-zero,
otherwise preserve the value inherited from the master socket via
sync_socket_options().

Signed-off-by: Geliang Tang <[email protected]>
---
 net/mptcp/sockopt.c | 5 +++++
 net/mptcp/subflow.c | 4 +++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index 5de371e29721..d79139eb5b8a 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -335,6 +335,8 @@ static int mptcp_setsockopt_sol_socket(struct mptcp_sock *msk, int optname,
 				sk->sk_bound_dev_if = ssk->sk_bound_dev_if;
 			else if (optname == SO_BINDTOIFINDEX)
 				sk->sk_bound_dev_if = ssk->sk_bound_dev_if;
+
+			sockopt_seq_inc(msk);
 		}
 		release_sock(sk);
 		return ret;
@@ -1704,6 +1706,9 @@ static void sync_socket_options(struct mptcp_sock *msk, struct sock *ssk)
 		assign_bit(b, &inet_sk(ssk)->inet_flags, src & BIT(b));
 
 	WRITE_ONCE(inet_sk(ssk)->local_port_range, READ_ONCE(inet_sk(sk)->local_port_range));
+
+	ssk->sk_reuse = sk->sk_reuse;
+	ssk->sk_reuseport = sk->sk_reuseport;
 }
 
 void mptcp_sockopt_sync_locked(struct mptcp_sock *msk, struct sock *ssk)
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index af81ad5e699d..47ff736c4d66 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1672,7 +1672,9 @@ int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_pm_local *local,
 	if (addr.ss_family == AF_INET6)
 		addrlen = sizeof(struct sockaddr_in6);
 #endif
-	ssk->sk_bound_dev_if = local->ifindex;
+	/* Only override the bound device if the path manager picked one. */
+	if (local->ifindex)
+		ssk->sk_bound_dev_if = local->ifindex;
 	err = kernel_bind(sf, (struct sockaddr_unsized *)&addr, addrlen);
 	if (err) {
 		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTXBINDERR);
-- 
2.53.0