netdev - [PATCH net-next v3 08/19] mptcp: Add setsockopt()/getsockopt() socket operations

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Message-id: <20200122005633.21229-9-cpaasch@apple.com>
Date:   Tue, 21 Jan 2020 16:56:22 -0800
From:   Christoph Paasch <cpaasch@...le.com>
To:     netdev@...r.kernel.org
Cc:     mptcp@...ts.01.org, Peter Krystad <peter.krystad@...ux.intel.com>,
        Paolo Abeni <pabeni@...hat.com>
Subject: [PATCH net-next v3 08/19] mptcp: Add setsockopt()/getsockopt() socket
 operations

From: Peter Krystad <peter.krystad@...ux.intel.com>

set/getsockopt behaviour with multiple subflows is undefined.
Therefore, for now, we return -EOPNOTSUPP unless we're in fallback mode.

Co-developed-by: Paolo Abeni <pabeni@...hat.com>
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
Signed-off-by: Peter Krystad <peter.krystad@...ux.intel.com>
Signed-off-by: Christoph Paasch <cpaasch@...le.com>
---
 net/mptcp/protocol.c | 58 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 249b2506a66a..875ca48de4b2 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -330,6 +330,62 @@ static void mptcp_destroy(struct sock *sk)
 {
 }
 
+static int mptcp_setsockopt(struct sock *sk, int level, int optname,
+			    char __user *uoptval, unsigned int optlen)
+{
+	struct mptcp_sock *msk = mptcp_sk(sk);
+	char __kernel *optval;
+	int ret = -EOPNOTSUPP;
+	struct socket *ssock;
+
+	/* will be treated as __user in tcp_setsockopt */
+	optval = (char __kernel __force *)uoptval;
+
+	pr_debug("msk=%p", msk);
+
+	/* @@ the meaning of setsockopt() when the socket is connected and
+	 * there are multiple subflows is not defined.
+	 */
+	lock_sock(sk);
+	ssock = __mptcp_socket_create(msk, MPTCP_SAME_STATE);
+	if (!IS_ERR(ssock)) {
+		pr_debug("subflow=%p", ssock->sk);
+		ret = kernel_setsockopt(ssock, level, optname, optval, optlen);
+	}
+	release_sock(sk);
+
+	return ret;
+}
+
+static int mptcp_getsockopt(struct sock *sk, int level, int optname,
+			    char __user *uoptval, int __user *uoption)
+{
+	struct mptcp_sock *msk = mptcp_sk(sk);
+	char __kernel *optval;
+	int ret = -EOPNOTSUPP;
+	int __kernel *option;
+	struct socket *ssock;
+
+	/* will be treated as __user in tcp_getsockopt */
+	optval = (char __kernel __force *)uoptval;
+	option = (int __kernel __force *)uoption;
+
+	pr_debug("msk=%p", msk);
+
+	/* @@ the meaning of getsockopt() when the socket is connected and
+	 * there are multiple subflows is not defined.
+	 */
+	lock_sock(sk);
+	ssock = __mptcp_socket_create(msk, MPTCP_SAME_STATE);
+	if (!IS_ERR(ssock)) {
+		pr_debug("subflow=%p", ssock->sk);
+		ret = kernel_getsockopt(ssock, level, optname, optval, option);
+	}
+	release_sock(sk);
+
+	return ret;
+}
+
 static int mptcp_get_port(struct sock *sk, unsigned short snum)
 {
 	struct mptcp_sock *msk = mptcp_sk(sk);
@@ -380,6 +436,8 @@ static struct proto mptcp_prot = {
 	.init		= mptcp_init_sock,
 	.close		= mptcp_close,
 	.accept		= mptcp_accept,
+	.setsockopt	= mptcp_setsockopt,
+	.getsockopt	= mptcp_getsockopt,
 	.shutdown	= tcp_shutdown,
 	.destroy	= mptcp_destroy,
 	.sendmsg	= mptcp_sendmsg,
-- 
2.23.0