ipvs: allow tunneling with gue encapsulation

ipip packets are blocked in some public cloud environments, this patch
allows gue encapsulation with the tunneling method, which would make
tunneling working in those environments.

Signed-off-by: Jacky Hu <hengqing.hu@gmail.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 80 insertions, 4 deletions

diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index 175349fcf91f..8d6f94b67772 100644
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -32,6 +32,7 @@
 #include <linux/slab.h>
 #include <linux/tcp.h>                  /* for tcphdr */
 #include <net/ip.h>
+#include <net/gue.h>
 #include <net/tcp.h>                    /* for csum_tcpudp_magic */
 #include <net/udp.h>
 #include <net/icmp.h>                   /* for icmp_send */
@@ -382,6 +383,10 @@ __ip_vs_get_out_rt(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
 		mtu = dst_mtu(&rt->dst);
 	} else {
 		mtu = dst_mtu(&rt->dst) - sizeof(struct iphdr);
+		if (!dest)
+			goto err_put;
+		if (dest->tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE)
+			mtu -= sizeof(struct udphdr) + sizeof(struct guehdr);
 		if (mtu < 68) {
 			IP_VS_DBG_RL("%s(): mtu less than 68\n", __func__);
 			goto err_put;
@@ -533,6 +538,10 @@ __ip_vs_get_out_rt_v6(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
 		mtu = dst_mtu(&rt->dst);
 	else {
 		mtu = dst_mtu(&rt->dst) - sizeof(struct ipv6hdr);
+		if (!dest)
+			goto err_put;
+		if (dest->tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE)
+			mtu -= sizeof(struct udphdr) + sizeof(struct guehdr);
 		if (mtu < IPV6_MIN_MTU) {
 			IP_VS_DBG_RL("%s(): mtu less than %d\n", __func__,
 				     IPV6_MIN_MTU);
@@ -989,6 +998,41 @@ static inline int __tun_gso_type_mask(int encaps_af, int orig_af)
 	}
 }
 
+static int
+ipvs_gue_encap(struct net *net, struct sk_buff *skb,
+	       struct ip_vs_conn *cp, __u8 *next_protocol)
+{
+	__be16 dport;
+	__be16 sport = udp_flow_src_port(net, skb, 0, 0, false);
+	struct udphdr  *udph;	/* Our new UDP header */
+	struct guehdr  *gueh;	/* Our new GUE header */
+
+	skb_push(skb, sizeof(struct guehdr));
+
+	gueh = (struct guehdr *)skb->data;
+
+	gueh->control = 0;
+	gueh->version = 0;
+	gueh->hlen = 0;
+	gueh->flags = 0;
+	gueh->proto_ctype = *next_protocol;
+
+	skb_push(skb, sizeof(struct udphdr));
+	skb_reset_transport_header(skb);
+
+	udph = udp_hdr(skb);
+
+	dport = cp->dest->tun_port;
+	udph->dest = dport;
+	udph->source = sport;
+	udph->len = htons(skb->len);
+	udph->check = 0;
+
+	*next_protocol = IPPROTO_UDP;
+
+	return 0;
+}
+
 /*
  *   IP Tunneling transmitter
  *
@@ -1025,6 +1069,7 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 	struct iphdr  *iph;			/* Our new IP header */
 	unsigned int max_headroom;		/* The extra header space needed */
 	int ret, local;
+	int tun_type, gso_type;
 
 	EnterFunction(10);
 
@@ -1046,6 +1091,11 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 	 */
 	max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct iphdr);
 
+	tun_type = cp->dest->tun_type;
+
+	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE)
+		max_headroom += sizeof(struct udphdr) + sizeof(struct guehdr);
+
 	/* We only care about the df field if sysctl_pmtu_disc(ipvs) is set */
 	dfp = sysctl_pmtu_disc(ipvs) ? &df : NULL;
 	skb = ip_vs_prepare_tunneled_skb(skb, cp->af, max_headroom,
@@ -1054,11 +1104,20 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 	if (IS_ERR(skb))
 		goto tx_error;
 
-	if (iptunnel_handle_offloads(skb, __tun_gso_type_mask(AF_INET, cp->af)))
+	gso_type = __tun_gso_type_mask(AF_INET, cp->af);
+	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE)
+		gso_type |= SKB_GSO_UDP_TUNNEL;
+
+	if (iptunnel_handle_offloads(skb, gso_type))
 		goto tx_error;
 
 	skb->transport_header = skb->network_header;
 
+	skb_set_inner_ipproto(skb, next_protocol);
+
+	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE)
+		ipvs_gue_encap(net, skb, cp, &next_protocol);
+
 	skb_push(skb, sizeof(struct iphdr));
 	skb_reset_network_header(skb);
 	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
@@ -1102,6 +1161,8 @@ int
 ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 		     struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh)
 {
+	struct netns_ipvs *ipvs = cp->ipvs;
+	struct net *net = ipvs->net;
 	struct rt6_info *rt;		/* Route to the other host */
 	struct in6_addr saddr;		/* Source for tunnel */
 	struct net_device *tdev;	/* Device to other host */
@@ -1112,10 +1173,11 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 	struct ipv6hdr  *iph;		/* Our new IP header */
 	unsigned int max_headroom;	/* The extra header space needed */
 	int ret, local;
+	int tun_type, gso_type;
 
 	EnterFunction(10);
 
-	local = __ip_vs_get_out_rt_v6(cp->ipvs, cp->af, skb, cp->dest,
+	local = __ip_vs_get_out_rt_v6(ipvs, cp->af, skb, cp->dest,
 				      &cp->daddr.in6,
 				      &saddr, ipvsh, 1,
 				      IP_VS_RT_MODE_LOCAL |
@@ -1134,17 +1196,31 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 	 */
 	max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct ipv6hdr);
 
+	tun_type = cp->dest->tun_type;
+
+	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE)
+		max_headroom += sizeof(struct udphdr) + sizeof(struct guehdr);
+
 	skb = ip_vs_prepare_tunneled_skb(skb, cp->af, max_headroom,
 					 &next_protocol, &payload_len,
 					 &dsfield, &ttl, NULL);
 	if (IS_ERR(skb))
 		goto tx_error;
 
-	if (iptunnel_handle_offloads(skb, __tun_gso_type_mask(AF_INET6, cp->af)))
+	gso_type = __tun_gso_type_mask(AF_INET6, cp->af);
+	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE)
+		gso_type |= SKB_GSO_UDP_TUNNEL;
+
+	if (iptunnel_handle_offloads(skb, gso_type))
 		goto tx_error;
 
 	skb->transport_header = skb->network_header;
 
+	skb_set_inner_ipproto(skb, next_protocol);
+
+	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE)
+		ipvs_gue_encap(net, skb, cp, &next_protocol);
+
 	skb_push(skb, sizeof(struct ipv6hdr));
 	skb_reset_network_header(skb);
 	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
@@ -1167,7 +1243,7 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 
 	ret = ip_vs_tunnel_xmit_prepare(skb, cp);
 	if (ret == NF_ACCEPT)
-		ip6_local_out(cp->ipvs->net, skb->sk, skb);
+		ip6_local_out(net, skb->sk, skb);
 	else if (ret == NF_DROP)
 		kfree_skb(skb);