mptcp: update local address flags when setting it

Just like in-kernel pm, when userspace pm does set_flags, it needs to send
out MP_PRIO signal, and also modify the flags of the corresponding address
entry in the local address list. This patch implements the missing logic.

Traverse all address entries on userspace_pm_local_addr_list to find the
local address entry, if bkup is true, set the flags of this entry with
FLAG_BACKUP, otherwise, clear FLAG_BACKUP.

Fixes: 892f396 ("mptcp: netlink: issue MP_PRIO signals from userspace PMs")
Cc: [email protected]
Signed-off-by: Geliang Tang <[email protected]>
Reviewed-by: Matthieu Baerts (NGI0) <[email protected]>
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: Geliang Tang

net/mptcp/pm_userspace.c

@@ -560,6 +560,7 @@ int mptcp_userspace_pm_set_flags(struct sk_buff *skb, struct genl_info *info)
 	struct nlattr *token = info->attrs[MPTCP_PM_ATTR_TOKEN];
 	struct nlattr *attr = info->attrs[MPTCP_PM_ATTR_ADDR];
 	struct net *net = sock_net(skb->sk);
+	struct mptcp_pm_addr_entry *entry;
 	struct mptcp_sock *msk;
 	int ret = -EINVAL;
 	struct sock *sk;
@@ -601,6 +602,17 @@ int mptcp_userspace_pm_set_flags(struct sk_buff *skb, struct genl_info *info)
 	if (loc.flags & MPTCP_PM_ADDR_FLAG_BACKUP)
 		bkup = 1;
 
+	spin_lock_bh(&msk->pm.lock);
+	list_for_each_entry(entry, &msk->pm.userspace_pm_local_addr_list, list) {
+		if (mptcp_addresses_equal(&entry->addr, &loc.addr, false)) {
+			if (bkup)
+				entry->flags |= MPTCP_PM_ADDR_FLAG_BACKUP;
+			else
+				entry->flags &= ~MPTCP_PM_ADDR_FLAG_BACKUP;
+		}
+	}
+	spin_unlock_bh(&msk->pm.lock);
+
 	lock_sock(sk);
 	ret = mptcp_pm_nl_mp_prio_send_ack(msk, &loc.addr, &rem.addr, bkup);
 	release_sock(sk);