lwtunnel: ignore any TUNNEL_OPTIONS_PRESENT flags set by users

TUNNEL_OPTIONS_PRESENT (TUNNEL_GENEVE_OPT|TUNNEL_VXLAN_OPT|
TUNNEL_ERSPAN_OPT) flags should be set only according to
tb[LWTUNNEL_IP_OPTS], which is done in ip_tun_parse_opts().

When setting info key.tun_flags, the TUNNEL_OPTIONS_PRESENT
bits in tb[LWTUNNEL_IP(6)_FLAGS] passed from users should
be ignored.

While at it, replace all (TUNNEL_GENEVE_OPT|TUNNEL_VXLAN_OPT|
TUNNEL_ERSPAN_OPT) with 'TUNNEL_OPTIONS_PRESENT'.

Fixes: 3093fbe7 ("route: Per route IP tunnel metadata via lightweight tunnel")
Fixes: 32a2b002 ("ipv6: route: per route IP tunnel metadata via lightweight tunnel")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ip_tunnel_core.c

@@ -451,7 +451,9 @@ static int ip_tun_build_state(struct nlattr *attr,
 		tun_info->key.tos = nla_get_u8(tb[LWTUNNEL_IP_TOS]);
 
 	if (tb[LWTUNNEL_IP_FLAGS])
-		tun_info->key.tun_flags |= nla_get_be16(tb[LWTUNNEL_IP_FLAGS]);
+		tun_info->key.tun_flags |=
+				(nla_get_be16(tb[LWTUNNEL_IP_FLAGS]) &
+				 ~TUNNEL_OPTIONS_PRESENT);
 
 	tun_info->mode = IP_TUNNEL_INFO_TX;
 	tun_info->options_len = opt_len;
@@ -550,8 +552,7 @@ static int ip_tun_fill_encap_opts(struct sk_buff *skb, int type,
 	struct nlattr *nest;
 	int err = 0;
 
-	if (!(tun_info->key.tun_flags &
-	      (TUNNEL_GENEVE_OPT | TUNNEL_VXLAN_OPT | TUNNEL_ERSPAN_OPT)))
+	if (!(tun_info->key.tun_flags & TUNNEL_OPTIONS_PRESENT))
 		return 0;
 
 	nest = nla_nest_start_noflag(skb, type);
@@ -596,8 +597,7 @@ static int ip_tun_opts_nlsize(struct ip_tunnel_info *info)
 {
 	int opt_len;
 
-	if (!(info->key.tun_flags &
-	      (TUNNEL_GENEVE_OPT | TUNNEL_VXLAN_OPT | TUNNEL_ERSPAN_OPT)))
+	if (!(info->key.tun_flags & TUNNEL_OPTIONS_PRESENT))
 		return 0;
 
 	opt_len = nla_total_size(0);		/* LWTUNNEL_IP_OPTS */
@@ -718,7 +718,9 @@ static int ip6_tun_build_state(struct nlattr *attr,
 		tun_info->key.tos = nla_get_u8(tb[LWTUNNEL_IP6_TC]);
 
 	if (tb[LWTUNNEL_IP6_FLAGS])
-		tun_info->key.tun_flags |= nla_get_be16(tb[LWTUNNEL_IP6_FLAGS]);
+		tun_info->key.tun_flags |=
+				(nla_get_be16(tb[LWTUNNEL_IP6_FLAGS]) &
+				 ~TUNNEL_OPTIONS_PRESENT);
 
 	tun_info->mode = IP_TUNNEL_INFO_TX | IP_TUNNEL_INFO_IPV6;
 	tun_info->options_len = opt_len;