[nrf fromtree] Bluetooth: host: Fix SMP local keys check when starting encryption

Fix SMP check of existing local keys when attempting to start security
with required security mode 1 level 4. The logic for checking the
conditions was wrong, leading to a situation where encryption would be
attempted to be started by the central instead of initiating a new
pairing procedure. This would fail when the connection was encrypted and
the connection would be disconnected.

Signed-off-by: Joakim Andersson <[email protected]>
(cherry picked from commit 83d5402)
Signed-off-by: Herman Berget <[email protected]>

Author: joerchan

subsys/bluetooth/host/smp.c

@@ -374,15 +374,15 @@ static bool smp_keys_check(struct bt_conn *conn)
 		return false;
 	}
 
-	if (conn->required_sec_level > BT_SECURITY_L2 &&
+	if (conn->required_sec_level >= BT_SECURITY_L3 &&
 	    !(conn->le.keys->flags & BT_KEYS_AUTHENTICATED)) {
 		return false;
 	}
 
-	if (conn->required_sec_level > BT_SECURITY_L3 &&
-	    !(conn->le.keys->flags & BT_KEYS_AUTHENTICATED) &&
-	    !(conn->le.keys->keys & BT_KEYS_LTK_P256) &&
-	    !(conn->le.keys->enc_size == BT_SMP_MAX_ENC_KEY_SIZE)) {
+	if (conn->required_sec_level >= BT_SECURITY_L4 &&
+	    !((conn->le.keys->flags & BT_KEYS_AUTHENTICATED) &&
+	      (conn->le.keys->keys & BT_KEYS_LTK_P256) &&
+	      (conn->le.keys->enc_size == BT_SMP_MAX_ENC_KEY_SIZE))) {
 		return false;
 	}