mptcp: add port number check for MP_JOIN

This patch adds two new helpers, subflow_use_different_sport and
subflow_use_different_dport, to check whether the subflow's source or
destination port number is different from the msk's port number. When
receiving the MP_JOIN's SYN/SYNACK/ACK, we do these port number checks
and print out the different port numbers.

And furthermore, when receiving the MP_JOIN's SYN/ACK, we also use a new
helper mptcp_pm_sport_in_anno_list to check whether this port number is
announced. If it isn't, we need to abort this connection.

This patch also populates the local address's port field in
local_address.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 22 insertions, 1 deletions

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index b71701a743a4..54f0ca73e68a 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -97,8 +97,8 @@ static bool address_zero(const struct mptcp_addr_info *addr)
 static void local_address(const struct sock_common *skc,
 			  struct mptcp_addr_info *addr)
 {
-	addr->port = 0;
 	addr->family = skc->skc_family;
+	addr->port = htons(skc->skc_num);
 	if (addr->family == AF_INET)
 		addr->addr.s_addr = skc->skc_rcv_saddr;
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
@@ -254,6 +254,27 @@ lookup_anno_list_by_saddr(struct mptcp_sock *msk,
 	return NULL;
 }
 
+bool mptcp_pm_sport_in_anno_list(struct mptcp_sock *msk, const struct sock *sk)
+{
+	struct mptcp_pm_add_entry *entry;
+	struct mptcp_addr_info saddr;
+	bool ret = false;
+
+	local_address((struct sock_common *)sk, &saddr);
+
+	spin_lock_bh(&msk->pm.lock);
+	list_for_each_entry(entry, &msk->pm.anno_list, list) {
+		if (addresses_equal(&entry->addr, &saddr, true)) {
+			ret = true;
+			goto out;
+		}
+	}
+
+out:
+	spin_unlock_bh(&msk->pm.lock);
+	return ret;
+}
+
 static void mptcp_pm_add_timer(struct timer_list *timer)
 {
 	struct mptcp_pm_add_entry *entry = from_timer(entry, timer, add_timer);