netfilter: add nf_ipv6_ops hook to fix xt_addrtype with IPv6
Quoting https://bugzilla.netfilter.org/show_bug.cgi?id=812:
[ ip6tables -m addrtype ]
When I tried to use in the nat/PREROUTING it messes up the
routing cache even if the rule didn't matched at all.
[..]
If I remove the --limit-iface-in from the non-working scenario, so just
use the -m addrtype --dst-type LOCAL it works!
This happens when LOCAL type matching is requested with --limit-iface-in,
and the default ipv6 route is via the interface the packet we test
arrived on.
Because xt_addrtype uses ip6_route_output, the ipv6 routing implementation
creates an unwanted cached entry, and the packet won't make it to the
real/expected destination.
Silently ignoring --limit-iface-in makes the routing work but it breaks
rule matching (--dst-type LOCAL with limit-iface-in is supposed to only
match if the dst address is configured on the incoming interface;
without --limit-iface-in it will match if the address is reachable
via lo).
The test should call ipv6_chk_addr() instead. However, this would add
a link-time dependency on ipv6.
There are two possible solutions:
1) Revert the commit that moved ipt_addrtype to xt_addrtype,
and put ipv6 specific code into ip6t_addrtype.
2) add new "nf_ipv6_ops" struct to register pointers to ipv6 functions.
While the former might seem preferable, Pablo pointed out that there
are more xt modules with link-time dependeny issues regarding ipv6,
so lets go for 2).
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index d1ab6ab..d1b2d80 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1487,7 +1487,7 @@
}
int ipv6_chk_addr(struct net *net, const struct in6_addr *addr,
- struct net_device *dev, int strict)
+ const struct net_device *dev, int strict)
{
struct inet6_ifaddr *ifp;
unsigned int hash = inet6_addr_hash(addr);
diff --git a/net/ipv6/netfilter.c b/net/ipv6/netfilter.c
index 72836f4..95f3f1d 100644
--- a/net/ipv6/netfilter.c
+++ b/net/ipv6/netfilter.c
@@ -10,6 +10,7 @@
#include <linux/netfilter.h>
#include <linux/netfilter_ipv6.h>
#include <linux/export.h>
+#include <net/addrconf.h>
#include <net/dst.h>
#include <net/ipv6.h>
#include <net/ip6_route.h>
@@ -186,6 +187,10 @@
return csum;
};
+static const struct nf_ipv6_ops ipv6ops = {
+ .chk_addr = ipv6_chk_addr,
+};
+
static const struct nf_afinfo nf_ip6_afinfo = {
.family = AF_INET6,
.checksum = nf_ip6_checksum,
@@ -198,6 +203,7 @@
int __init ipv6_netfilter_init(void)
{
+ RCU_INIT_POINTER(nf_ipv6_ops, &ipv6ops);
return nf_register_afinfo(&nf_ip6_afinfo);
}
@@ -206,5 +212,6 @@
*/
void ipv6_netfilter_fini(void)
{
+ RCU_INIT_POINTER(nf_ipv6_ops, NULL);
nf_unregister_afinfo(&nf_ip6_afinfo);
}
diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index 07c865a..857ca9f 100644
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -30,6 +30,8 @@
const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO] __read_mostly;
EXPORT_SYMBOL(nf_afinfo);
+const struct nf_ipv6_ops __rcu *nf_ipv6_ops __read_mostly;
+EXPORT_SYMBOL_GPL(nf_ipv6_ops);
int nf_register_afinfo(const struct nf_afinfo *afinfo)
{
diff --git a/net/netfilter/xt_addrtype.c b/net/netfilter/xt_addrtype.c
index 49c5ff7..68ff29f 100644
--- a/net/netfilter/xt_addrtype.c
+++ b/net/netfilter/xt_addrtype.c
@@ -22,6 +22,7 @@
#include <net/ip6_fib.h>
#endif
+#include <linux/netfilter_ipv6.h>
#include <linux/netfilter/xt_addrtype.h>
#include <linux/netfilter/x_tables.h>
@@ -33,12 +34,12 @@
#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
static u32 match_lookup_rt6(struct net *net, const struct net_device *dev,
- const struct in6_addr *addr)
+ const struct in6_addr *addr, u16 mask)
{
const struct nf_afinfo *afinfo;
struct flowi6 flow;
struct rt6_info *rt;
- u32 ret;
+ u32 ret = 0;
int route_err;
memset(&flow, 0, sizeof(flow));
@@ -49,12 +50,19 @@
rcu_read_lock();
afinfo = nf_get_afinfo(NFPROTO_IPV6);
- if (afinfo != NULL)
- route_err = afinfo->route(net, (struct dst_entry **)&rt,
- flowi6_to_flowi(&flow), !!dev);
- else
- route_err = 1;
+ if (afinfo != NULL) {
+ const struct nf_ipv6_ops *v6ops;
+ if (dev && (mask & XT_ADDRTYPE_LOCAL)) {
+ v6ops = nf_get_ipv6_ops();
+ if (v6ops && v6ops->chk_addr(net, addr, dev, true))
+ ret = XT_ADDRTYPE_LOCAL;
+ }
+ route_err = afinfo->route(net, (struct dst_entry **)&rt,
+ flowi6_to_flowi(&flow), false);
+ } else {
+ route_err = 1;
+ }
rcu_read_unlock();
if (route_err)
@@ -62,15 +70,12 @@
if (rt->rt6i_flags & RTF_REJECT)
ret = XT_ADDRTYPE_UNREACHABLE;
- else
- ret = 0;
- if (rt->rt6i_flags & RTF_LOCAL)
+ if (dev == NULL && rt->rt6i_flags & RTF_LOCAL)
ret |= XT_ADDRTYPE_LOCAL;
if (rt->rt6i_flags & RTF_ANYCAST)
ret |= XT_ADDRTYPE_ANYCAST;
-
dst_release(&rt->dst);
return ret;
}
@@ -90,7 +95,7 @@
if ((XT_ADDRTYPE_LOCAL | XT_ADDRTYPE_ANYCAST |
XT_ADDRTYPE_UNREACHABLE) & mask)
- return !!(mask & match_lookup_rt6(net, dev, addr));
+ return !!(mask & match_lookup_rt6(net, dev, addr, mask));
return true;
}
