Date: Sat Oct 21 00:25:15 2017 +0300
From: Shmulik Ladkani <shmulik.ladkani@gmail.com>
References: bsc#1166978
Subject: ip6_tunnel: Allow rcv/xmit even if remote address is a local address
Patch-mainline: v4.14-rc5
Git-commit: 908d140a87a794bf89717ceae54aba5ce86c52e4
Acked-by: Otto Hollmann <otto.hollmann@suse.com>
ip6_tunnel: Allow rcv/xmit even if remote address is a local address
Currently, ip6_tnl_xmit_ctl drops tunneled packets if the remote
address (outer v6 destination) is one of host's locally configured
addresses.
Same applies to ip6_tnl_rcv_ctl: it drops packets if the remote address
(outer v6 source) is a local address.
This prevents using ipxip6 (and ip6_gre) tunnels whose local/remote
endpoints are on same host; OTOH v4 tunnels (ipip or gre) allow such
configurations.
An example where this proves useful is a system where entities are
identified by their unique v6 addresses, and use tunnels to encapsulate
traffic between them. The limitation prevents placing several entities
on same host.
Introduce IP6_TNL_F_ALLOW_LOCAL_REMOTE which allows to bypass this
restriction.
Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/uapi/linux/ip6_tunnel.h b/include/uapi/linux/ip6_tunnel.h
index 425926c467d7..ffebbe365478 100644
--- a/include/uapi/linux/ip6_tunnel.h
+++ b/include/uapi/linux/ip6_tunnel.h
@@ -20,6 +20,8 @@
#define IP6_TNL_F_RCV_DSCP_COPY 0x10
/* copy fwmark from inner packet */
#define IP6_TNL_F_USE_ORIG_FWMARK 0x20
+/* allow remote endpoint on the local node */
+#define IP6_TNL_F_ALLOW_LOCAL_REMOTE 0x40
struct ip6_tnl_parm {
char name[IFNAMSIZ]; /* name of tunnel device */
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 4212879ff35e..439d65f7e094 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -770,7 +770,8 @@ int ip6_tnl_rcv_ctl(struct ip6_tnl *t,
if ((ipv6_addr_is_multicast(laddr) ||
likely(ipv6_chk_addr(net, laddr, ldev, 0))) &&
- likely(!ipv6_chk_addr(net, raddr, NULL, 0)))
+ ((p->flags & IP6_TNL_F_ALLOW_LOCAL_REMOTE) ||
+ likely(!ipv6_chk_addr(net, raddr, NULL, 0))))
ret = 1;
}
return ret;
@@ -1000,7 +1001,8 @@ int ip6_tnl_xmit_ctl(struct ip6_tnl *t,
if (unlikely(!ipv6_chk_addr(net, laddr, ldev, 0)))
pr_warn("%s xmit: Local address not yet configured!\n",
p->name);
- else if (!ipv6_addr_is_multicast(raddr) &&
+ else if (!(p->flags & IP6_TNL_F_ALLOW_LOCAL_REMOTE) &&
+ !ipv6_addr_is_multicast(raddr) &&
unlikely(ipv6_chk_addr(net, raddr, NULL, 0)))
pr_warn("%s xmit: Routing loop! Remote address found on this node!\n",
p->name);