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.
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
---
Instead of adding new IP6T_SO_ORIGINAL_DST, we could also
simply re-use existing SO_ORIGINAL_DST ipv4 define. Any Preferences?
include/uapi/linux/in6.h | 1 +
include/uapi/linux/netfilter_ipv6/ip6_tables.h | 3 +
net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c | 61 ++++++++++++++++++++++++
3 files changed, 65 insertions(+), 0 deletions(-)
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 @@ struct in6_flowlabel_req {
*
* 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 @@ struct ip6t_error {
#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 */
diff --git a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
index 8860d23..02dcafd 100644
--- a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
+++ b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
@@ -21,6 +21,7 @@
#include <linux/netfilter_bridge.h>
#include <linux/netfilter_ipv6.h>
+#include <linux/netfilter_ipv6/ip6_tables.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_l4proto.h>
@@ -295,6 +296,50 @@ static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = {
},
};
+static int
+ipv6_getorigdst(struct sock *sk, int optval, void __user *user, int *len)
+{
+ const struct inet_sock *inet = inet_sk(sk);
+ const struct ipv6_pinfo *inet6 = inet6_sk(sk);
+ const struct nf_conntrack_tuple_hash *h;
+ struct sockaddr_in6 sin6;
+ struct nf_conntrack_tuple tuple = { .src.l3num = NFPROTO_IPV6 };
+ struct nf_conn *ct;
+
+ tuple.src.u3.in6 = inet6->rcv_saddr;
+ tuple.src.u.tcp.port = inet->inet_sport;
+ tuple.dst.u3.in6 = inet6->daddr;
+ tuple.dst.u.tcp.port = inet->inet_dport;
+ tuple.dst.protonum = sk->sk_protocol;
+
+ if (sk->sk_protocol != IPPROTO_TCP && sk->sk_protocol != IPPROTO_SCTP)
+ return -ENOPROTOOPT;
+
+ if (*len < 0 || (unsigned int) *len < sizeof(sin6))
+ return -EINVAL;
+
+ h = nf_conntrack_find_get(sock_net(sk), NF_CT_DEFAULT_ZONE, &tuple);
+ if (!h) {
+ pr_debug("IP6T_SO_ORIGINAL_DST: Can't find %pI6c/%u-%pI6c/%u.\n",
+ &tuple.src.u3.ip6, ntohs(tuple.src.u.tcp.port),
+ &tuple.dst.u3.ip6, ntohs(tuple.dst.u.tcp.port));
+ return -ENOENT;
+ }
+
+ ct = nf_ct_tuplehash_to_ctrack(h);
+
+ sin6.sin6_family = AF_INET6;
+ sin6.sin6_port = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u.tcp.port;
+ sin6.sin6_flowinfo = inet6->flow_label & IPV6_FLOWINFO_MASK;
+ memcpy(&sin6.sin6_addr,
+ &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.in6,
+ sizeof(sin6.sin6_addr));
+ sin6.sin6_scope_id = sk->sk_bound_dev_if;
+
+ nf_ct_put(ct);
+ return copy_to_user(user, &sin6, sizeof(sin6)) ? -EFAULT : 0;
+}
+
#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
#include <linux/netfilter/nfnetlink.h>
@@ -359,6 +404,14 @@ MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET6));
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Yasuyuki KOZAKAI @USAGI <yasuyuki.kozakai@xxxxxxxxxxxxx>");
+static struct nf_sockopt_ops so_getorigdst6 = {
+ .pf = NFPROTO_IPV6,
+ .get_optmin = IP6T_SO_ORIGINAL_DST,
+ .get_optmax = IP6T_SO_ORIGINAL_DST + 1,
+ .get = ipv6_getorigdst,
+ .owner = THIS_MODULE,
+};
+
static int ipv6_net_init(struct net *net)
{
int ret = 0;
@@ -425,6 +478,12 @@ static int __init nf_conntrack_l3proto_ipv6_init(void)
need_conntrack();
nf_defrag_ipv6_enable();
+ ret = nf_register_sockopt(&so_getorigdst6);
+ if (ret < 0) {
+ pr_err("Unable to register netfilter socket option\n");
+ return ret;
+ }
+
ret = register_pernet_subsys(&ipv6_net_ops);
if (ret < 0)
goto cleanup_pernet;
@@ -440,6 +499,7 @@ static int __init nf_conntrack_l3proto_ipv6_init(void)
cleanup_ipv6:
unregister_pernet_subsys(&ipv6_net_ops);
cleanup_pernet:
+ nf_unregister_sockopt(&so_getorigdst6);
return ret;
}
@@ -448,6 +508,7 @@ static void __exit nf_conntrack_l3proto_ipv6_fini(void)
synchronize_net();
nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
unregister_pernet_subsys(&ipv6_net_ops);
+ nf_unregister_sockopt(&so_getorigdst6);
}
module_init(nf_conntrack_l3proto_ipv6_init);
--
1.7.8.6
--
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