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ipvs: allow tunneling with gre encapsulation
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windows real servers can handle gre tunnels, this patch allows
gre encapsulation with the tunneling method, thereby letting ipvs
be load balancer for windows-based services

Signed-off-by: Vadim Fedorenko <vfedorenko@yandex-team.ru>
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>
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Vadim Fedorenko authored and Pablo Neira Ayuso committed Jul 4, 2019
1 parent 0d9cb30 commit 6f7b841
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Showing 3 changed files with 65 additions and 3 deletions.
1 change: 1 addition & 0 deletions include/uapi/linux/ip_vs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -128,6 +128,7 @@
enum {
IP_VS_CONN_F_TUNNEL_TYPE_IPIP = 0, /* IPIP */
IP_VS_CONN_F_TUNNEL_TYPE_GUE, /* GUE */
IP_VS_CONN_F_TUNNEL_TYPE_GRE, /* GRE */
IP_VS_CONN_F_TUNNEL_TYPE_MAX,
};

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1 change: 1 addition & 0 deletions net/netfilter/ipvs/ip_vs_ctl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -525,6 +525,7 @@ static void ip_vs_rs_hash(struct netns_ipvs *ipvs, struct ip_vs_dest *dest)
port = dest->tun_port;
break;
case IP_VS_CONN_F_TUNNEL_TYPE_IPIP:
case IP_VS_CONN_F_TUNNEL_TYPE_GRE:
port = 0;
break;
default:
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66 changes: 63 additions & 3 deletions net/netfilter/ipvs/ip_vs_xmit.c
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@
#include <linux/tcp.h> /* for tcphdr */
#include <net/ip.h>
#include <net/gue.h>
#include <net/gre.h>
#include <net/tcp.h> /* for csum_tcpudp_magic */
#include <net/udp.h>
#include <net/icmp.h> /* for icmp_send */
Expand Down Expand Up @@ -388,6 +389,12 @@ __ip_vs_get_out_rt(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM) &&
skb->ip_summed == CHECKSUM_PARTIAL)
mtu -= GUE_PLEN_REMCSUM + GUE_LEN_PRIV;
} else if (dest->tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
__be16 tflags = 0;

if (dest->tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
tflags |= TUNNEL_CSUM;
mtu -= gre_calc_hlen(tflags);
}
if (mtu < 68) {
IP_VS_DBG_RL("%s(): mtu less than 68\n", __func__);
Expand Down Expand Up @@ -548,6 +555,12 @@ __ip_vs_get_out_rt_v6(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM) &&
skb->ip_summed == CHECKSUM_PARTIAL)
mtu -= GUE_PLEN_REMCSUM + GUE_LEN_PRIV;
} else if (dest->tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
__be16 tflags = 0;

if (dest->tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
tflags |= TUNNEL_CSUM;
mtu -= gre_calc_hlen(tflags);
}
if (mtu < IPV6_MIN_MTU) {
IP_VS_DBG_RL("%s(): mtu less than %d\n", __func__,
Expand Down Expand Up @@ -1079,6 +1092,24 @@ ipvs_gue_encap(struct net *net, struct sk_buff *skb,
return 0;
}

static void
ipvs_gre_encap(struct net *net, struct sk_buff *skb,
struct ip_vs_conn *cp, __u8 *next_protocol)
{
__be16 proto = *next_protocol == IPPROTO_IPIP ?
htons(ETH_P_IP) : htons(ETH_P_IPV6);
__be16 tflags = 0;
size_t hdrlen;

if (cp->dest->tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
tflags |= TUNNEL_CSUM;

hdrlen = gre_calc_hlen(tflags);
gre_build_header(skb, hdrlen, tflags, proto, 0, 0);

*next_protocol = IPPROTO_GRE;
}

/*
* IP Tunneling transmitter
*
Expand Down Expand Up @@ -1151,6 +1182,15 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
gue_hdrlen = sizeof(struct guehdr) + gue_optlen;

max_headroom += sizeof(struct udphdr) + gue_hdrlen;
} else if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
size_t gre_hdrlen;
__be16 tflags = 0;

if (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
tflags |= TUNNEL_CSUM;
gre_hdrlen = gre_calc_hlen(tflags);

max_headroom += gre_hdrlen;
}

/* We only care about the df field if sysctl_pmtu_disc(ipvs) is set */
Expand All @@ -1172,6 +1212,11 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
skb->ip_summed == CHECKSUM_PARTIAL) {
gso_type |= SKB_GSO_TUNNEL_REMCSUM;
}
} else if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
if (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
gso_type |= SKB_GSO_GRE_CSUM;
else
gso_type |= SKB_GSO_GRE;
}

if (iptunnel_handle_offloads(skb, gso_type))
Expand All @@ -1192,8 +1237,8 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
check = true;

udp_set_csum(!check, skb, saddr, cp->daddr.ip, skb->len);
}

} else if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE)
ipvs_gre_encap(net, skb, cp, &next_protocol);

skb_push(skb, sizeof(struct iphdr));
skb_reset_network_header(skb);
Expand Down Expand Up @@ -1287,6 +1332,15 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
gue_hdrlen = sizeof(struct guehdr) + gue_optlen;

max_headroom += sizeof(struct udphdr) + gue_hdrlen;
} else if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
size_t gre_hdrlen;
__be16 tflags = 0;

if (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
tflags |= TUNNEL_CSUM;
gre_hdrlen = gre_calc_hlen(tflags);

max_headroom += gre_hdrlen;
}

skb = ip_vs_prepare_tunneled_skb(skb, cp->af, max_headroom,
Expand All @@ -1306,6 +1360,11 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
skb->ip_summed == CHECKSUM_PARTIAL) {
gso_type |= SKB_GSO_TUNNEL_REMCSUM;
}
} else if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
if (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
gso_type |= SKB_GSO_GRE_CSUM;
else
gso_type |= SKB_GSO_GRE;
}

if (iptunnel_handle_offloads(skb, gso_type))
Expand All @@ -1326,7 +1385,8 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
check = true;

udp6_set_csum(!check, skb, &saddr, &cp->daddr.in6, skb->len);
}
} else if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE)
ipvs_gre_encap(net, skb, cp, &next_protocol);

skb_push(skb, sizeof(struct ipv6hdr));
skb_reset_network_header(skb);
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