[PATCH] ipvs: allow tunneling with gue encapsulation

From: Jacky Hu
Date: Tue Mar 12 2019 - 02:58:51 EST


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@xxxxxxxxx>
---
include/uapi/linux/ip_vs.h | 17 +++++++-
net/netfilter/ipvs/ip_vs_ctl.c | 4 +-
net/netfilter/ipvs/ip_vs_xmit.c | 71 ++++++++++++++++++++++++++++++++-
3 files changed, 87 insertions(+), 5 deletions(-)

diff --git a/include/uapi/linux/ip_vs.h b/include/uapi/linux/ip_vs.h
index 1c916b2f89dc..6637e45b93f4 100644
--- a/include/uapi/linux/ip_vs.h
+++ b/include/uapi/linux/ip_vs.h
@@ -96,13 +96,25 @@
#define IP_VS_CONN_F_TEMPLATE 0x1000 /* template, not connection */
#define IP_VS_CONN_F_ONE_PACKET 0x2000 /* forward only one packet */

+/* tunneling with gue */
+#define IP_VS_CONN_F_GUE 0x0008
+
+/* gue destination port bit 0 */
+#define IP_VS_CONN_F_GUE_PORT_LSB 0x4000
+
+/* gue destination port bit 1-15 */
+#define IP_VS_CONN_F_GUE_PORT_MSB 0xFFFFE0000
+
/* Initial bits allowed in backup server */
#define IP_VS_CONN_F_BACKUP_MASK (IP_VS_CONN_F_FWD_MASK | \
IP_VS_CONN_F_NOOUTPUT | \
IP_VS_CONN_F_INACTIVE | \
IP_VS_CONN_F_SEQ_MASK | \
IP_VS_CONN_F_NO_CPORT | \
- IP_VS_CONN_F_TEMPLATE \
+ IP_VS_CONN_F_TEMPLATE | \
+ IP_VS_CONN_F_GUE | \
+ IP_VS_CONN_F_GUE_PORT_MSB | \
+ IP_VS_CONN_F_GUE_PORT_LSB \
)

/* Bits allowed to update in backup server */
@@ -116,6 +128,9 @@
#define IP_VS_CONN_F_DEST_MASK (IP_VS_CONN_F_FWD_MASK | \
IP_VS_CONN_F_ONE_PACKET | \
IP_VS_CONN_F_NFCT | \
+ IP_VS_CONN_F_GUE | \
+ IP_VS_CONN_F_GUE_PORT_MSB | \
+ IP_VS_CONN_F_GUE_PORT_LSB | \
0)

#define IP_VS_SCHEDNAME_MAXLEN 16
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index 432141f04af3..cecfb52cdea4 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -3169,7 +3169,7 @@ static int ip_vs_genl_fill_dest(struct sk_buff *skb, struct ip_vs_dest *dest)
nla_put_be16(skb, IPVS_DEST_ATTR_PORT, dest->port) ||
nla_put_u32(skb, IPVS_DEST_ATTR_FWD_METHOD,
(atomic_read(&dest->conn_flags) &
- IP_VS_CONN_F_FWD_MASK)) ||
+ IP_VS_CONN_F_DEST_MASK)) ||
nla_put_u32(skb, IPVS_DEST_ATTR_WEIGHT,
atomic_read(&dest->weight)) ||
nla_put_u32(skb, IPVS_DEST_ATTR_U_THRESH, dest->u_threshold) ||
@@ -3305,7 +3305,7 @@ static int ip_vs_genl_parse_dest(struct ip_vs_dest_user_kern *udest,
return -EINVAL;

udest->conn_flags = nla_get_u32(nla_fwd)
- & IP_VS_CONN_F_FWD_MASK;
+ & IP_VS_CONN_F_DEST_MASK;
udest->weight = nla_get_u32(nla_weight);
udest->u_threshold = nla_get_u32(nla_u_thresh);
udest->l_threshold = nla_get_u32(nla_l_thresh);
diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index 473cce2a5231..2667b587b91d 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 */
@@ -989,6 +990,42 @@ static inline int __tun_gso_type_mask(int encaps_af, int orig_af)
}
}

+static int
+__build_gue_header(struct net *net, struct sk_buff *skb,
+ struct ip_vs_conn *cp, __u8 *next_protocol)
+{
+ __be16 dport;
+ __be16 sport;
+ 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 = htons(((cp->flags >> 16) & 0xFFFE) | ((cp->flags >> 14) & 1));
+ sport = udp_flow_src_port(net, skb, 0, 0, false);
+ 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 +1062,8 @@ 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;
+ bool gue = false;
+ int type;

EnterFunction(10);

@@ -1041,11 +1080,16 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
rt = skb_rtable(skb);
tdev = rt->dst.dev;

+ gue = (bool)(cp->flags & IP_VS_CONN_F_GUE);
+
/*
* Okay, now see if we can stuff it in the buffer as-is.
*/
max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct iphdr);

+ if (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 +1098,19 @@ 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)))
+ if (gue)
+ type = SKB_GSO_UDP_TUNNEL;
+ else
+ type = __tun_gso_type_mask(AF_INET, cp->af);
+
+ if (iptunnel_handle_offloads(skb, type))
goto tx_error;

skb->transport_header = skb->network_header;

+ if (gue)
+ __build_gue_header(dev_net(tdev), skb, cp, &next_protocol);
+
skb_push(skb, sizeof(struct iphdr));
skb_reset_network_header(skb);
memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
@@ -1112,6 +1164,8 @@ 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;
+ bool gue = false;
+ int type;

EnterFunction(10);

@@ -1129,22 +1183,35 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
rt = (struct rt6_info *) skb_dst(skb);
tdev = rt->dst.dev;

+ gue = (bool)(cp->flags & IP_VS_CONN_F_GUE);
+
/*
* Okay, now see if we can stuff it in the buffer as-is.
*/
max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct ipv6hdr);

+ if (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)))
+ if (gue)
+ type = SKB_GSO_UDP_TUNNEL;
+ else
+ type = __tun_gso_type_mask(AF_INET6, cp->af);
+
+ if (iptunnel_handle_offloads(skb, type))
goto tx_error;

skb->transport_header = skb->network_header;

+ if (gue)
+ __build_gue_header(dev_net(tdev), skb, cp, &next_protocol);
+
skb_push(skb, sizeof(struct ipv6hdr));
skb_reset_network_header(skb);
memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
--
2.21.0