ipip: support MPLS over IPv4

Extend the IPIP driver to support MPLS over IPv4. The implementation is an
extension of existing support for IPv4 over IPv4 and is based of multiple
inner-protocol support for the SIT driver.

Signed-off-by: Simon Horman <simon.horman@netronome.com>
Reviewed-by: Dinan Gunawardena <dinan.gunawardena@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ipip.c

@@ -148,14 +148,14 @@ static int ipip_err(struct sk_buff *skb, u32 info)
 
 	if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
 		ipv4_update_pmtu(skb, dev_net(skb->dev), info,
-				 t->parms.link, 0, IPPROTO_IPIP, 0);
+				 t->parms.link, 0, iph->protocol, 0);
 		err = 0;
 		goto out;
 	}
 
 	if (type == ICMP_REDIRECT) {
 		ipv4_redirect(skb, dev_net(skb->dev), t->parms.link, 0,
-			      IPPROTO_IPIP, 0);
+			      iph->protocol, 0);
 		err = 0;
 		goto out;
 	}
@@ -177,12 +177,19 @@ out:
 	return err;
 }
 
-static const struct tnl_ptk_info tpi = {
+static const struct tnl_ptk_info ipip_tpi = {
 	/* no tunnel info required for ipip. */
 	.proto = htons(ETH_P_IP),
 };
 
-static int ipip_rcv(struct sk_buff *skb)
+#if IS_ENABLED(CONFIG_MPLS)
+static const struct tnl_ptk_info mplsip_tpi = {
+	/* no tunnel info required for mplsip. */
+	.proto = htons(ETH_P_MPLS_UC),
+};
+#endif
+
+static int ipip_tunnel_rcv(struct sk_buff *skb, u8 ipproto)
 {
 	struct net *net = dev_net(skb->dev);
 	struct ip_tunnel_net *itn = net_generic(net, ipip_net_id);
@@ -193,11 +200,23 @@ static int ipip_rcv(struct sk_buff *skb)
 	tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex, TUNNEL_NO_KEY,
 			iph->saddr, iph->daddr, 0);
 	if (tunnel) {
+		const struct tnl_ptk_info *tpi;
+
+		if (tunnel->parms.iph.protocol != ipproto &&
+		    tunnel->parms.iph.protocol != 0)
+			goto drop;
+
 		if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 			goto drop;
-		if (iptunnel_pull_header(skb, 0, tpi.proto, false))
+#if IS_ENABLED(CONFIG_MPLS)
+		if (ipproto == IPPROTO_MPLS)
+			tpi = &mplsip_tpi;
+		else
+#endif
+			tpi = &ipip_tpi;
+		if (iptunnel_pull_header(skb, 0, tpi->proto, false))
 			goto drop;
-		return ip_tunnel_rcv(tunnel, skb, &tpi, NULL, log_ecn_error);
+		return ip_tunnel_rcv(tunnel, skb, tpi, NULL, log_ecn_error);
 	}
 
 	return -1;
@@ -207,24 +226,51 @@ drop:
 	return 0;
 }
 
+static int ipip_rcv(struct sk_buff *skb)
+{
+	return ipip_tunnel_rcv(skb, IPPROTO_IPIP);
+}
+
+#if IS_ENABLED(CONFIG_MPLS)
+static int mplsip_rcv(struct sk_buff *skb)
+{
+	return ipip_tunnel_rcv(skb, IPPROTO_MPLS);
+}
+#endif
+
 /*
  *	This function assumes it is being called from dev_queue_xmit()
  *	and that skb is filled properly by that function.
  */
-static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb,
+				    struct net_device *dev)
 {
 	struct ip_tunnel *tunnel = netdev_priv(dev);
 	const struct iphdr  *tiph = &tunnel->parms.iph;
+	u8 ipproto;
+
+	switch (skb->protocol) {
+	case htons(ETH_P_IP):
+		ipproto = IPPROTO_IPIP;
+		break;
+#if IS_ENABLED(CONFIG_MPLS)
+	case htons(ETH_P_MPLS_UC):
+		ipproto = IPPROTO_MPLS;
+		break;
+#endif
+	default:
+		goto tx_error;
+	}
 
-	if (unlikely(skb->protocol != htons(ETH_P_IP)))
+	if (tiph->protocol != ipproto && tiph->protocol != 0)
 		goto tx_error;
 
 	if (iptunnel_handle_offloads(skb, SKB_GSO_IPXIP4))
 		goto tx_error;
 
-	skb_set_inner_ipproto(skb, IPPROTO_IPIP);
+	skb_set_inner_ipproto(skb, ipproto);
 
-	ip_tunnel_xmit(skb, dev, tiph, tiph->protocol);
+	ip_tunnel_xmit(skb, dev, tiph, ipproto);
 	return NETDEV_TX_OK;
 
 tx_error:
@@ -234,6 +280,20 @@ tx_error:
 	return NETDEV_TX_OK;
 }
 
+static bool ipip_tunnel_ioctl_verify_protocol(u8 ipproto)
+{
+	switch (ipproto) {
+	case 0:
+	case IPPROTO_IPIP:
+#if IS_ENABLED(CONFIG_MPLS)
+	case IPPROTO_MPLS:
+#endif
+		return true;
+	}
+
+	return false;
+}
+
 static int
 ipip_tunnel_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 {
@@ -244,7 +304,8 @@ ipip_tunnel_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 		return -EFAULT;
 
 	if (cmd == SIOCADDTUNNEL || cmd == SIOCCHGTUNNEL) {
-		if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPIP ||
+		if (p.iph.version != 4 ||
+		    !ipip_tunnel_ioctl_verify_protocol(p.iph.protocol) ||
 		    p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 			return -EINVAL;
 	}
@@ -301,10 +362,23 @@ static int ipip_tunnel_init(struct net_device *dev)
 
 	tunnel->tun_hlen = 0;
 	tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen;
-	tunnel->parms.iph.protocol = IPPROTO_IPIP;
 	return ip_tunnel_init(dev);
 }
 
+static int ipip_tunnel_validate(struct nlattr *tb[], struct nlattr *data[])
+{
+	u8 proto;
+
+	if (!data || !data[IFLA_IPTUN_PROTO])
+		return 0;
+
+	proto = nla_get_u8(data[IFLA_IPTUN_PROTO]);
+	if (proto != IPPROTO_IPIP && proto != IPPROTO_MPLS && proto != 0)
+		return -EINVAL;
+
+	return 0;
+}
+
 static void ipip_netlink_parms(struct nlattr *data[],
 			       struct ip_tunnel_parm *parms)
 {
@@ -335,6 +409,9 @@ static void ipip_netlink_parms(struct nlattr *data[],
 	if (data[IFLA_IPTUN_TOS])
 		parms->iph.tos = nla_get_u8(data[IFLA_IPTUN_TOS]);
 
+	if (data[IFLA_IPTUN_PROTO])
+		parms->iph.protocol = nla_get_u8(data[IFLA_IPTUN_PROTO]);
+
 	if (!data[IFLA_IPTUN_PMTUDISC] || nla_get_u8(data[IFLA_IPTUN_PMTUDISC]))
 		parms->iph.frag_off = htons(IP_DF);
 }
@@ -427,6 +504,8 @@ static size_t ipip_get_size(const struct net_device *dev)
 		nla_total_size(1) +
 		/* IFLA_IPTUN_TOS */
 		nla_total_size(1) +
+		/* IFLA_IPTUN_PROTO */
+		nla_total_size(1) +
 		/* IFLA_IPTUN_PMTUDISC */
 		nla_total_size(1) +
 		/* IFLA_IPTUN_ENCAP_TYPE */
@@ -450,6 +529,7 @@ static int ipip_fill_info(struct sk_buff *skb, const struct net_device *dev)
 	    nla_put_in_addr(skb, IFLA_IPTUN_REMOTE, parm->iph.daddr) ||
 	    nla_put_u8(skb, IFLA_IPTUN_TTL, parm->iph.ttl) ||
 	    nla_put_u8(skb, IFLA_IPTUN_TOS, parm->iph.tos) ||
+	    nla_put_u8(skb, IFLA_IPTUN_PROTO, parm->iph.protocol) ||
 	    nla_put_u8(skb, IFLA_IPTUN_PMTUDISC,
 		       !!(parm->iph.frag_off & htons(IP_DF))))
 		goto nla_put_failure;
@@ -476,6 +556,7 @@ static const struct nla_policy ipip_policy[IFLA_IPTUN_MAX + 1] = {
 	[IFLA_IPTUN_REMOTE]		= { .type = NLA_U32 },
 	[IFLA_IPTUN_TTL]		= { .type = NLA_U8 },
 	[IFLA_IPTUN_TOS]		= { .type = NLA_U8 },
+	[IFLA_IPTUN_PROTO]		= { .type = NLA_U8 },
 	[IFLA_IPTUN_PMTUDISC]		= { .type = NLA_U8 },
 	[IFLA_IPTUN_ENCAP_TYPE]		= { .type = NLA_U16 },
 	[IFLA_IPTUN_ENCAP_FLAGS]	= { .type = NLA_U16 },
@@ -489,6 +570,7 @@ static struct rtnl_link_ops ipip_link_ops __read_mostly = {
 	.policy		= ipip_policy,
 	.priv_size	= sizeof(struct ip_tunnel),
 	.setup		= ipip_tunnel_setup,
+	.validate	= ipip_tunnel_validate,
 	.newlink	= ipip_newlink,
 	.changelink	= ipip_changelink,
 	.dellink	= ip_tunnel_dellink,
@@ -503,6 +585,14 @@ static struct xfrm_tunnel ipip_handler __read_mostly = {
 	.priority	=	1,
 };
 
+#if IS_ENABLED(CONFIG_MPLS)
+static struct xfrm_tunnel mplsip_handler __read_mostly = {
+	.handler	=	mplsip_rcv,
+	.err_handler	=	ipip_err,
+	.priority	=	1,
+};
+#endif
+
 static int __net_init ipip_init_net(struct net *net)
 {
 	return ip_tunnel_init_net(net, ipip_net_id, &ipip_link_ops, "tunl0");
@@ -525,7 +615,7 @@ static int __init ipip_init(void)
 {
 	int err;
 
-	pr_info("ipip: IPv4 over IPv4 tunneling driver\n");
+	pr_info("ipip: IPv4 and MPLS over IPv4 tunneling driver\n");
 
 	err = register_pernet_device(&ipip_net_ops);
 	if (err < 0)
@@ -533,8 +623,15 @@ static int __init ipip_init(void)
 	err = xfrm4_tunnel_register(&ipip_handler, AF_INET);
 	if (err < 0) {
 		pr_info("%s: can't register tunnel\n", __func__);
-		goto xfrm_tunnel_failed;
+		goto xfrm_tunnel_ipip_failed;
+	}
+#if IS_ENABLED(CONFIG_MPLS)
+	err = xfrm4_tunnel_register(&mplsip_handler, AF_MPLS);
+	if (err < 0) {
+		pr_info("%s: can't register tunnel\n", __func__);
+		goto xfrm_tunnel_mplsip_failed;
 	}
+#endif
 	err = rtnl_link_register(&ipip_link_ops);
 	if (err < 0)
 		goto rtnl_link_failed;
@@ -543,8 +640,13 @@ out:
 	return err;
 
 rtnl_link_failed:
+#if IS_ENABLED(CONFIG_MPLS)
+	xfrm4_tunnel_deregister(&mplsip_handler, AF_INET);
+xfrm_tunnel_mplsip_failed:
+
+#endif
 	xfrm4_tunnel_deregister(&ipip_handler, AF_INET);
-xfrm_tunnel_failed:
+xfrm_tunnel_ipip_failed:
 	unregister_pernet_device(&ipip_net_ops);
 	goto out;
 }
@@ -554,7 +656,10 @@ static void __exit ipip_fini(void)
 	rtnl_link_unregister(&ipip_link_ops);
 	if (xfrm4_tunnel_deregister(&ipip_handler, AF_INET))
 		pr_info("%s: can't deregister tunnel\n", __func__);
-
+#if IS_ENABLED(CONFIG_MPLS)
+	if (xfrm4_tunnel_deregister(&mplsip_handler, AF_MPLS))
+		pr_info("%s: can't deregister tunnel\n", __func__);
+#endif
 	unregister_pernet_device(&ipip_net_ops);
 }