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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: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Shmulik Ladkani 2017-10-21 00:25:15 +03:00 committed by David S. Miller
parent 6a331e1513
commit 908d140a87
2 changed files with 6 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/uapi/linux/ip6_tunnel.h
View File

@ -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 */

6
net/ipv6/ip6_tunnel.c
View File

@ -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);