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Commit 908d140a authored by Shmulik Ladkani's avatar Shmulik Ladkani Committed by David S. Miller
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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: default avatarShmulik Ladkani <shmulik.ladkani@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6a331e15

include/uapi/linux/ip6_tunnel.h

+2 −0
Original line number Diff line number Diff line
@@ -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 */

net/ipv6/ip6_tunnel.c

+4 −2
Original line number Diff line number Diff line
@@ -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);