netdev - [PATCH net 3/4] mptcp: provide subflow aware release function

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Message-Id: <eba48b97ded37ff2bd9598adbe01f75f86e221fa.1613755058.git.pabeni@redhat.com>
Date:   Fri, 19 Feb 2021 18:35:39 +0100
From:   Paolo Abeni <pabeni@...hat.com>
To:     netdev@...r.kernel.org
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, mptcp@...ts.01.org,
        Florian Westphal <fw@...len.de>
Subject: [PATCH net 3/4] mptcp: provide subflow aware release function

From: Florian Westphal <fw@...len.de>

mptcp re-used inet(6)_release, so the subflow sockets are ignored.
Need to invoke ip(v6)_mc_drop_socket function to ensure mcast join
resources get free'd.

Fixes: 717e79c867ca5 ("mptcp: Add setsockopt()/getsockopt() socket operations")
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/110
Acked-by: Paolo Abeni <pabeni@...hat.com>
Signed-off-by: Florian Westphal <fw@...len.de>
---
 net/mptcp/protocol.c | 55 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 53 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 78bd4bed07ac..0a6d12d2967d 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -11,6 +11,7 @@
 #include <linux/netdevice.h>
 #include <linux/sched/signal.h>
 #include <linux/atomic.h>
+#include <linux/igmp.h>
 #include <net/sock.h>
 #include <net/inet_common.h>
 #include <net/inet_hashtables.h>
@@ -19,6 +20,7 @@
 #include <net/tcp_states.h>
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 #include <net/transp_v6.h>
+#include <net/addrconf.h>
 #endif
 #include <net/mptcp.h>
 #include <net/xfrm.h>
@@ -3374,10 +3376,34 @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock,
 	return mask;
 }
 
+static int mptcp_release(struct socket *sock)
+{
+	struct mptcp_subflow_context *subflow;
+	struct sock *sk = sock->sk;
+	struct mptcp_sock *msk;
+
+	if (!sk)
+		return 0;
+
+	lock_sock(sk);
+
+	msk = mptcp_sk(sk);
+
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+
+		ip_mc_drop_socket(ssk);
+	}
+
+	release_sock(sk);
+
+	return inet_release(sock);
+}
+
 static const struct proto_ops mptcp_stream_ops = {
 	.family		   = PF_INET,
 	.owner		   = THIS_MODULE,
-	.release	   = inet_release,
+	.release	   = mptcp_release,
 	.bind		   = mptcp_bind,
 	.connect	   = mptcp_stream_connect,
 	.socketpair	   = sock_no_socketpair,
@@ -3424,10 +3450,35 @@ void __init mptcp_proto_init(void)
 }
 
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
+static int mptcp6_release(struct socket *sock)
+{
+	struct mptcp_subflow_context *subflow;
+	struct mptcp_sock *msk;
+	struct sock *sk = sock->sk;
+
+	if (!sk)
+		return 0;
+
+	lock_sock(sk);
+
+	msk = mptcp_sk(sk);
+
+	mptcp_for_each_subflow(msk, subflow) {
+		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+
+		ip_mc_drop_socket(ssk);
+		ipv6_sock_mc_close(ssk);
+		ipv6_sock_ac_close(ssk);
+	}
+
+	release_sock(sk);
+	return inet6_release(sock);
+}
+
 static const struct proto_ops mptcp_v6_stream_ops = {
 	.family		   = PF_INET6,
 	.owner		   = THIS_MODULE,
-	.release	   = inet6_release,
+	.release	   = mptcp6_release,
 	.bind		   = mptcp_bind,
 	.connect	   = mptcp_stream_connect,
 	.socketpair	   = sock_no_socketpair,
-- 
2.26.2