netfilter: ipv6: add getsockopt to retrieve origdst
userspace can query the original ipv4 destination address of a REDIRECTed
connection via
getsockopt(m_sock, SOL_IP, SO_ORIGINAL_DST, &m_server_addr, &addrsize)
but for ipv6 no such option existed.
This adds getsockopt(..., IPPROTO_IPV6, IP6T_SO_ORIGINAL_DST, ...).
Without this, userspace needs to parse /proc or use ctnetlink, which
appears to be overkill.
This uses option number 80 for IP6T_SO_ORIGINAL_DST, which is spare,
to use the same number we use in the IPv4 socket option SO_ORIGINAL_DST.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/include/uapi/linux/in6.h b/include/uapi/linux/in6.h
index 1e31599..f79c372 100644
--- a/include/uapi/linux/in6.h
+++ b/include/uapi/linux/in6.h
@@ -240,6 +240,7 @@
*
* IP6T_SO_GET_REVISION_MATCH 68
* IP6T_SO_GET_REVISION_TARGET 69
+ * IP6T_SO_ORIGINAL_DST 80
*/
/* RFC5014: Source address selection */
diff --git a/include/uapi/linux/netfilter_ipv6/ip6_tables.h b/include/uapi/linux/netfilter_ipv6/ip6_tables.h
index bf1ef65..649c680 100644
--- a/include/uapi/linux/netfilter_ipv6/ip6_tables.h
+++ b/include/uapi/linux/netfilter_ipv6/ip6_tables.h
@@ -178,6 +178,9 @@
#define IP6T_SO_GET_REVISION_TARGET (IP6T_BASE_CTL + 5)
#define IP6T_SO_GET_MAX IP6T_SO_GET_REVISION_TARGET
+/* obtain original address if REDIRECT'd connection */
+#define IP6T_SO_ORIGINAL_DST 80
+
/* ICMP matching stuff */
struct ip6t_icmp {
__u8 type; /* type to match */