From: Geliang Tang <tanggeliang@kylinos.cn>

This patch extracts TCP_ULP setsockopt operation into a tcp_sock_set_ulp()
helper so that it can also be used in MPTCP.

Add MPTCP ULP setsockopt support in mptcp_setsockopt_sol_tcp().

This option cannot be set when the socket is in CLOSE or LISTEN state.

Co-developed-by: Gang Yan <yangang@kylinos.cn>
Signed-off-by: Gang Yan <yangang@kylinos.cn>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 include/linux/tcp.h |  1 +
 net/ipv4/tcp.c      | 42 ++++++++++++++++++++++++------------------
 net/mptcp/sockopt.c | 27 ++++++++++++++++++++++++++-
 3 files changed, 51 insertions(+), 19 deletions(-)

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 2bb1cbd3eeab..00538b1aa2f0 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -654,6 +654,7 @@ int tcp_sock_set_syncnt(struct sock *sk, int val);
 int tcp_sock_set_user_timeout(struct sock *sk, int val);
 int tcp_sock_set_maxseg(struct sock *sk, int val);
 int tcp_sock_get_ulp(struct sock *sk, sockptr_t optval, sockptr_t optlen);
+int tcp_sock_set_ulp(struct sock *sk, sockptr_t optval, unsigned int optlen);
 
 static inline bool dst_tcp_usec_ts(const struct dst_entry *dst)
 {
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 55d8fb848842..8ebd2402847e 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3858,6 +3858,28 @@ int tcp_sock_set_maxseg(struct sock *sk, int val)
 	return 0;
 }
 
+int tcp_sock_set_ulp(struct sock *sk, sockptr_t optval, unsigned int optlen)
+{
+	char name[TCP_ULP_NAME_MAX];
+	int err = 0;
+	size_t len;
+	int val;
+
+	if (optlen < 1)
+		return -EINVAL;
+
+	len = min_t(long, TCP_ULP_NAME_MAX - 1, optlen);
+	val = strncpy_from_sockptr(name, optval, len);
+	if (val < 0)
+		return -EFAULT;
+	name[val] = 0;
+
+	sockopt_lock_sock(sk);
+	err = tcp_set_ulp(sk, name);
+	sockopt_release_sock(sk);
+	return err;
+}
+
 /*
  *	Socket option code for TCP.
  */
@@ -3891,24 +3913,8 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
 		sockopt_release_sock(sk);
 		return err;
 	}
-	case TCP_ULP: {
-		char name[TCP_ULP_NAME_MAX];
-
-		if (optlen < 1)
-			return -EINVAL;
-
-		val = strncpy_from_sockptr(name, optval,
-					min_t(long, TCP_ULP_NAME_MAX - 1,
-					      optlen));
-		if (val < 0)
-			return -EFAULT;
-		name[val] = 0;
-
-		sockopt_lock_sock(sk);
-		err = tcp_set_ulp(sk, name);
-		sockopt_release_sock(sk);
-		return err;
-	}
+	case TCP_ULP:
+		return tcp_sock_set_ulp(sk, optval, optlen);
 	case TCP_FASTOPEN_KEY: {
 		__u8 key[TCP_FASTOPEN_KEY_BUF_LENGTH];
 		__u8 *backup_key = NULL;
diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index a6230f7910fd..d04eb98aaa32 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -12,6 +12,7 @@
 #include <net/protocol.h>
 #include <net/tcp.h>
 #include <net/mptcp.h>
+#include <net/tls.h>
 #include "protocol.h"
 
 #define MIN_INFO_OPTLEN_SIZE		16
@@ -567,6 +568,7 @@ static bool mptcp_supported_sockopt(int level, int optname)
 		case TCP_FASTOPEN_CONNECT:
 		case TCP_FASTOPEN_KEY:
 		case TCP_FASTOPEN_NO_COOKIE:
+		case TCP_ULP:
 			return true;
 		}
 
@@ -815,6 +817,29 @@ static int mptcp_setsockopt_all_sf(struct mptcp_sock *msk, int level,
 	return ret;
 }
 
+static int mptcp_setsockopt_tcp_ulp(struct sock *sk, sockptr_t optval,
+				    unsigned int optlen)
+{
+	char name[TCP_ULP_NAME_MAX];
+	size_t len;
+	int val;
+
+	if (optlen < 1)
+		return -EINVAL;
+
+	len = min_t(long, TCP_ULP_NAME_MAX - 1, optlen);
+	val = strncpy_from_sockptr(name, optval, len);
+	if (val < 0)
+		return -EFAULT;
+	name[val] = 0;
+
+	if (strcmp(name, "tls\0"))
+		return -EOPNOTSUPP;
+	if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))
+		return -ENOTCONN;
+	return tcp_sock_set_ulp(sk, optval, optlen);
+}
+
 static int mptcp_setsockopt_sol_tcp(struct mptcp_sock *msk, int optname,
 				    sockptr_t optval, unsigned int optlen)
 {
@@ -823,7 +848,7 @@ static int mptcp_setsockopt_sol_tcp(struct mptcp_sock *msk, int optname,
 
 	switch (optname) {
 	case TCP_ULP:
-		return -EOPNOTSUPP;
+		return mptcp_setsockopt_tcp_ulp(sk, optval, optlen);
 	case TCP_CONGESTION:
 		return mptcp_setsockopt_sol_tcp_congestion(msk, optval, optlen);
 	case TCP_DEFER_ACCEPT:
-- 
2.53.0