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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>
This commit is contained in:
Florian Westphal 2012-10-30 01:08:49 +00:00 committed by Pablo Neira Ayuso
parent 6229b75d8d
commit 121d1e0941
3 changed files with 65 additions and 0 deletions
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1
include/uapi/linux/in6.h
View File

@ -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 */

3
include/uapi/linux/netfilter_ipv6/ip6_tables.h
View File

@ -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 */

61
net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
View File

@ -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@toshiba.co.jp>");
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);