From: Julian Anastasov <j...@ssi.bg>
Recognize GRE tunnels in received ICMP errors and
properly strip the tunnel headers.
Signed-off-by: Julian Anastasov <j...@ssi.bg>
Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.org>
---
net/netfilter/ipvs/ip_vs_core.c | 46 +++++++++++++++++++++++++++++++++++++----
1 file changed, 42 insertions(+), 4 deletions(-)
diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
index e8651fd621ef..dd4727a5d6ec 100644
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c
@@ -35,6 +35,7 @@
#include <net/udp.h>
#include <net/icmp.h> /* for icmp_send */
#include <net/gue.h>
+#include <net/gre.h>
#include <net/route.h>
#include <net/ip6_checksum.h>
#include <net/netns/generic.h> /* net_generic() */
@@ -1610,6 +1611,38 @@ static int ipvs_udp_decap(struct netns_ipvs *ipvs,
struct sk_buff *skb,
return 0;
}
+/* Check the GRE tunnel and return its header length */
+static int ipvs_gre_decap(struct netns_ipvs *ipvs, struct sk_buff *skb,
+ unsigned int offset, __u16 af,
+ const union nf_inet_addr *daddr, __u8 *proto)
+{
+ struct gre_base_hdr _greh, *greh;
+ struct ip_vs_dest *dest;
+
+ greh = skb_header_pointer(skb, offset, sizeof(_greh), &_greh);
+ if (!greh)
+ goto unk;
+ dest = ip_vs_find_tunnel(ipvs, af, daddr, 0);
+ if (!dest)
+ goto unk;
+ if (dest->tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
+ __be16 type;
+
+ /* Only support version 0 and C (csum) */
+ if ((greh->flags & ~GRE_CSUM) != 0)
+ goto unk;
+ type = greh->protocol;
+ /* Later we can support also IPPROTO_IPV6 */
+ if (type != htons(ETH_P_IP))
+ goto unk;
+ *proto = IPPROTO_IPIP;
+ return gre_calc_hlen(gre_flags_to_tnl_flags(greh->flags));
+ }
+
+unk:
+ return 0;
+}
+
/*
* Handle ICMP messages in the outside-to-inside direction (incoming).
* Find any that might be relevant, check against existing connections,
@@ -1689,7 +1722,8 @@ ip_vs_in_icmp(struct netns_ipvs *ipvs, struct sk_buff
*skb, int *related,
if (cih == NULL)
return NF_ACCEPT; /* The packet looks wrong, ignore */
ipip = true;
- } else if (cih->protocol == IPPROTO_UDP && /* Can be UDP encap */
+ } else if ((cih->protocol == IPPROTO_UDP || /* Can be UDP encap */
+ cih->protocol == IPPROTO_GRE) && /* Can be GRE encap */
/* Error for our tunnel must arrive at LOCAL_IN */
(skb_rtable(skb)->rt_flags & RTCF_LOCAL)) {
__u8 iproto;
@@ -1699,10 +1733,14 @@ ip_vs_in_icmp(struct netns_ipvs *ipvs, struct sk_buff
*skb, int *related,
if (unlikely(cih->frag_off & htons(IP_OFFSET)))
return NF_ACCEPT;
offset2 = offset + cih->ihl * 4;
- ulen = ipvs_udp_decap(ipvs, skb, offset2, AF_INET, raddr,
- &iproto);
+ if (cih->protocol == IPPROTO_UDP)
+ ulen = ipvs_udp_decap(ipvs, skb, offset2, AF_INET,
+ raddr, &iproto);
+ else
+ ulen = ipvs_gre_decap(ipvs, skb, offset2, AF_INET,
+ raddr, &iproto);
if (ulen > 0) {
- /* Skip IP and UDP tunnel headers */
+ /* Skip IP and UDP/GRE tunnel headers */
offset = offset2 + ulen;
/* Now we should be at the original IP header */
cih = skb_header_pointer(skb, offset, sizeof(_ciph),
--
2.11.0
