netdev - [RFC PATCH v2 15/45] mptcp: Add setsockopt()/getsockopt() socket operations

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Message-Id: <20191002233655.24323-16-mathew.j.martineau@linux.intel.com>
Date:   Wed,  2 Oct 2019 16:36:25 -0700
From:   Mat Martineau <mathew.j.martineau@...ux.intel.com>
To:     netdev@...r.kernel.org, edumazet@...gle.com
Cc:     Peter Krystad <peter.krystad@...ux.intel.com>, cpaasch@...le.com,
        fw@...len.de, pabeni@...hat.com, dcaratti@...hat.com,
        matthieu.baerts@...sares.net
Subject: [RFC PATCH v2 15/45] 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.

Signed-off-by: Peter Krystad <peter.krystad@...ux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
---
 net/mptcp/protocol.c | 67 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index dba4d7a4a61a..41588758f74b 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -28,6 +28,17 @@ static struct socket *__mptcp_fallback_get_ref(const struct mptcp_sock *msk)
 	return msk->subflow;
 }
 
+static struct socket *mptcp_fallback_get_ref(const struct mptcp_sock *msk)
+{
+	struct socket *ssock;
+
+	lock_sock((struct sock *)msk);
+	ssock = __mptcp_fallback_get_ref(msk);
+	release_sock((struct sock *)msk);
+
+	return ssock;
+}
+
 static struct sock *mptcp_subflow_get_ref(const struct mptcp_sock *msk)
 {
 	struct mptcp_subflow_context *subflow;
@@ -224,6 +235,60 @@ 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;
+	struct socket *ssock;
+	int ret;
+
+	/* will be treated as __user in tcp_setsockopt */
+	optval = (char __kernel __force *)uoptval;
+
+	pr_debug("msk=%p", msk);
+	ssock = mptcp_fallback_get_ref(msk);
+	if (ssock) {
+		pr_debug("subflow=%p", ssock->sk);
+		ret = kernel_setsockopt(ssock, level, optname, optval, optlen);
+		sock_put(ssock->sk);
+		return ret;
+	}
+
+	/* @@ the meaning of setsockopt() when the socket is connected and
+	 * there are multiple subflows is not defined.
+	 */
+	return -EOPNOTSUPP;
+}
+
+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 __kernel *option;
+	struct socket *ssock;
+	int ret;
+
+	/* will be treated as __user in tcp_getsockopt */
+	optval = (char __kernel __force *)uoptval;
+	option = (int __kernel __force *)uoption;
+
+	pr_debug("msk=%p", msk);
+	ssock = mptcp_fallback_get_ref(msk);
+	if (ssock) {
+		pr_debug("subflow=%p", ssock->sk);
+		ret = kernel_getsockopt(ssock, level, optname, optval, option);
+		sock_put(ssock->sk);
+		return ret;
+	}
+
+	/* @@ the meaning of getsockopt() when the socket is connected and
+	 * there are multiple subflows is not defined.
+	 */
+	return -EOPNOTSUPP;
+}
+
 static int mptcp_get_port(struct sock *sk, unsigned short snum)
 {
 	struct mptcp_sock *msk = mptcp_sk(sk);
@@ -282,6 +347,8 @@ 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