netfilter: nat: merge ipv4 and ipv6 masquerade functionality
Before:
text data bss dec hex filename
13916 1412 4128 19456 4c00 nf_nat.ko
4510 968 4 5482 156a nf_nat_ipv4.ko
5146 944 8 6098 17d2 nf_nat_ipv6.ko
After:
text data bss dec hex filename
16566 1576 4136 22278 5706 nf_nat.ko
3187 844 0 4031 fbf nf_nat_ipv4.ko
3598 844 0 4442 115a nf_nat_ipv6.ko
... so no drastic changes in combined size.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index fefd63a..5a753cec 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -431,6 +431,9 @@
config NF_NAT_REDIRECT
bool
+config NF_NAT_MASQUERADE
+ bool
+
config NETFILTER_SYNPROXY
tristate
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index e66067b..c791070 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -56,6 +56,7 @@
obj-$(CONFIG_NF_NAT) += nf_nat.o
nf_nat-$(CONFIG_NF_NAT_REDIRECT) += nf_nat_redirect.o
+nf_nat-$(CONFIG_NF_NAT_MASQUERADE) += nf_nat_masquerade.o
# NAT helpers
obj-$(CONFIG_NF_NAT_AMANDA) += nf_nat_amanda.o
diff --git a/net/netfilter/nf_nat_masquerade.c b/net/netfilter/nf_nat_masquerade.c
new file mode 100644
index 0000000..86fa4dc
--- /dev/null
+++ b/net/netfilter/nf_nat_masquerade.c
@@ -0,0 +1,362 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/types.h>
+#include <linux/atomic.h>
+#include <linux/inetdevice.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_ipv6.h>
+
+#include <net/netfilter/ipv4/nf_nat_masquerade.h>
+#include <net/netfilter/ipv6/nf_nat_masquerade.h>
+
+static DEFINE_MUTEX(masq_mutex);
+static unsigned int masq_refcnt __read_mostly;
+
+unsigned int
+nf_nat_masquerade_ipv4(struct sk_buff *skb, unsigned int hooknum,
+ const struct nf_nat_range2 *range,
+ const struct net_device *out)
+{
+ struct nf_conn *ct;
+ struct nf_conn_nat *nat;
+ enum ip_conntrack_info ctinfo;
+ struct nf_nat_range2 newrange;
+ const struct rtable *rt;
+ __be32 newsrc, nh;
+
+ WARN_ON(hooknum != NF_INET_POST_ROUTING);
+
+ ct = nf_ct_get(skb, &ctinfo);
+
+ WARN_ON(!(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
+ ctinfo == IP_CT_RELATED_REPLY)));
+
+ /* Source address is 0.0.0.0 - locally generated packet that is
+ * probably not supposed to be masqueraded.
+ */
+ if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip == 0)
+ return NF_ACCEPT;
+
+ rt = skb_rtable(skb);
+ nh = rt_nexthop(rt, ip_hdr(skb)->daddr);
+ newsrc = inet_select_addr(out, nh, RT_SCOPE_UNIVERSE);
+ if (!newsrc) {
+ pr_info("%s ate my IP address\n", out->name);
+ return NF_DROP;
+ }
+
+ nat = nf_ct_nat_ext_add(ct);
+ if (nat)
+ nat->masq_index = out->ifindex;
+
+ /* Transfer from original range. */
+ memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
+ memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
+ newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
+ newrange.min_addr.ip = newsrc;
+ newrange.max_addr.ip = newsrc;
+ newrange.min_proto = range->min_proto;
+ newrange.max_proto = range->max_proto;
+
+ /* Hand modified range to generic setup. */
+ return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
+}
+EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv4);
+
+static int device_cmp(struct nf_conn *i, void *ifindex)
+{
+ const struct nf_conn_nat *nat = nfct_nat(i);
+
+ if (!nat)
+ return 0;
+ return nat->masq_index == (int)(long)ifindex;
+}
+
+static int masq_device_event(struct notifier_block *this,
+ unsigned long event,
+ void *ptr)
+{
+ const struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+ struct net *net = dev_net(dev);
+
+ if (event == NETDEV_DOWN) {
+ /* Device was downed. Search entire table for
+ * conntracks which were associated with that device,
+ * and forget them.
+ */
+
+ nf_ct_iterate_cleanup_net(net, device_cmp,
+ (void *)(long)dev->ifindex, 0, 0);
+ }
+
+ return NOTIFY_DONE;
+}
+
+static int inet_cmp(struct nf_conn *ct, void *ptr)
+{
+ struct in_ifaddr *ifa = (struct in_ifaddr *)ptr;
+ struct net_device *dev = ifa->ifa_dev->dev;
+ struct nf_conntrack_tuple *tuple;
+
+ if (!device_cmp(ct, (void *)(long)dev->ifindex))
+ return 0;
+
+ tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
+
+ return ifa->ifa_address == tuple->dst.u3.ip;
+}
+
+static int masq_inet_event(struct notifier_block *this,
+ unsigned long event,
+ void *ptr)
+{
+ struct in_device *idev = ((struct in_ifaddr *)ptr)->ifa_dev;
+ struct net *net = dev_net(idev->dev);
+
+ /* The masq_dev_notifier will catch the case of the device going
+ * down. So if the inetdev is dead and being destroyed we have
+ * no work to do. Otherwise this is an individual address removal
+ * and we have to perform the flush.
+ */
+ if (idev->dead)
+ return NOTIFY_DONE;
+
+ if (event == NETDEV_DOWN)
+ nf_ct_iterate_cleanup_net(net, inet_cmp, ptr, 0, 0);
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block masq_dev_notifier = {
+ .notifier_call = masq_device_event,
+};
+
+static struct notifier_block masq_inet_notifier = {
+ .notifier_call = masq_inet_event,
+};
+
+int nf_nat_masquerade_ipv4_register_notifier(void)
+{
+ int ret = 0;
+
+ mutex_lock(&masq_mutex);
+ /* check if the notifier was already set */
+ if (++masq_refcnt > 1)
+ goto out_unlock;
+
+ /* Register for device down reports */
+ ret = register_netdevice_notifier(&masq_dev_notifier);
+ if (ret)
+ goto err_dec;
+ /* Register IP address change reports */
+ ret = register_inetaddr_notifier(&masq_inet_notifier);
+ if (ret)
+ goto err_unregister;
+
+ mutex_unlock(&masq_mutex);
+ return ret;
+
+err_unregister:
+ unregister_netdevice_notifier(&masq_dev_notifier);
+err_dec:
+ masq_refcnt--;
+out_unlock:
+ mutex_unlock(&masq_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv4_register_notifier);
+
+void nf_nat_masquerade_ipv4_unregister_notifier(void)
+{
+ mutex_lock(&masq_mutex);
+ /* check if the notifier still has clients */
+ if (--masq_refcnt > 0)
+ goto out_unlock;
+
+ unregister_netdevice_notifier(&masq_dev_notifier);
+ unregister_inetaddr_notifier(&masq_inet_notifier);
+out_unlock:
+ mutex_unlock(&masq_mutex);
+}
+EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv4_unregister_notifier);
+
+#if IS_ENABLED(CONFIG_IPV6)
+static atomic_t v6_worker_count __read_mostly;
+
+static int
+nat_ipv6_dev_get_saddr(struct net *net, const struct net_device *dev,
+ const struct in6_addr *daddr, unsigned int srcprefs,
+ struct in6_addr *saddr)
+{
+#ifdef CONFIG_IPV6_MODULE
+ const struct nf_ipv6_ops *v6_ops = nf_get_ipv6_ops();
+
+ if (!v6_ops)
+ return -EHOSTUNREACH;
+
+ return v6_ops->dev_get_saddr(net, dev, daddr, srcprefs, saddr);
+#else
+ return ipv6_dev_get_saddr(net, dev, daddr, srcprefs, saddr);
+#endif
+}
+
+unsigned int
+nf_nat_masquerade_ipv6(struct sk_buff *skb, const struct nf_nat_range2 *range,
+ const struct net_device *out)
+{
+ enum ip_conntrack_info ctinfo;
+ struct nf_conn_nat *nat;
+ struct in6_addr src;
+ struct nf_conn *ct;
+ struct nf_nat_range2 newrange;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ WARN_ON(!(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
+ ctinfo == IP_CT_RELATED_REPLY)));
+
+ if (nat_ipv6_dev_get_saddr(nf_ct_net(ct), out,
+ &ipv6_hdr(skb)->daddr, 0, &src) < 0)
+ return NF_DROP;
+
+ nat = nf_ct_nat_ext_add(ct);
+ if (nat)
+ nat->masq_index = out->ifindex;
+
+ newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
+ newrange.min_addr.in6 = src;
+ newrange.max_addr.in6 = src;
+ newrange.min_proto = range->min_proto;
+ newrange.max_proto = range->max_proto;
+
+ return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
+}
+EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6);
+
+struct masq_dev_work {
+ struct work_struct work;
+ struct net *net;
+ struct in6_addr addr;
+ int ifindex;
+};
+
+static int inet6_cmp(struct nf_conn *ct, void *work)
+{
+ struct masq_dev_work *w = (struct masq_dev_work *)work;
+ struct nf_conntrack_tuple *tuple;
+
+ if (!device_cmp(ct, (void *)(long)w->ifindex))
+ return 0;
+
+ tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
+
+ return ipv6_addr_equal(&w->addr, &tuple->dst.u3.in6);
+}
+
+static void iterate_cleanup_work(struct work_struct *work)
+{
+ struct masq_dev_work *w;
+
+ w = container_of(work, struct masq_dev_work, work);
+
+ nf_ct_iterate_cleanup_net(w->net, inet6_cmp, (void *)w, 0, 0);
+
+ put_net(w->net);
+ kfree(w);
+ atomic_dec(&v6_worker_count);
+ module_put(THIS_MODULE);
+}
+
+/* atomic notifier; can't call nf_ct_iterate_cleanup_net (it can sleep).
+ *
+ * Defer it to the system workqueue.
+ *
+ * As we can have 'a lot' of inet_events (depending on amount of ipv6
+ * addresses being deleted), we also need to limit work item queue.
+ */
+static int masq_inet6_event(struct notifier_block *this,
+ unsigned long event, void *ptr)
+{
+ struct inet6_ifaddr *ifa = ptr;
+ const struct net_device *dev;
+ struct masq_dev_work *w;
+ struct net *net;
+
+ if (event != NETDEV_DOWN || atomic_read(&v6_worker_count) >= 16)
+ return NOTIFY_DONE;
+
+ dev = ifa->idev->dev;
+ net = maybe_get_net(dev_net(dev));
+ if (!net)
+ return NOTIFY_DONE;
+
+ if (!try_module_get(THIS_MODULE))
+ goto err_module;
+
+ w = kmalloc(sizeof(*w), GFP_ATOMIC);
+ if (w) {
+ atomic_inc(&v6_worker_count);
+
+ INIT_WORK(&w->work, iterate_cleanup_work);
+ w->ifindex = dev->ifindex;
+ w->net = net;
+ w->addr = ifa->addr;
+ schedule_work(&w->work);
+
+ return NOTIFY_DONE;
+ }
+
+ module_put(THIS_MODULE);
+ err_module:
+ put_net(net);
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block masq_inet6_notifier = {
+ .notifier_call = masq_inet6_event,
+};
+
+int nf_nat_masquerade_ipv6_register_notifier(void)
+{
+ int ret = 0;
+
+ mutex_lock(&masq_mutex);
+ /* check if the notifier is already set */
+ if (++masq_refcnt > 1)
+ goto out_unlock;
+
+ ret = register_netdevice_notifier(&masq_dev_notifier);
+ if (ret)
+ goto err_dec;
+
+ ret = register_inet6addr_notifier(&masq_inet6_notifier);
+ if (ret)
+ goto err_unregister;
+
+ mutex_unlock(&masq_mutex);
+ return ret;
+
+err_unregister:
+ unregister_netdevice_notifier(&masq_dev_notifier);
+err_dec:
+ masq_refcnt--;
+out_unlock:
+ mutex_unlock(&masq_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_register_notifier);
+
+void nf_nat_masquerade_ipv6_unregister_notifier(void)
+{
+ mutex_lock(&masq_mutex);
+ /* check if the notifier still has clients */
+ if (--masq_refcnt > 0)
+ goto out_unlock;
+
+ unregister_inet6addr_notifier(&masq_inet6_notifier);
+ unregister_netdevice_notifier(&masq_dev_notifier);
+out_unlock:
+ mutex_unlock(&masq_mutex);
+}
+EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6_unregister_notifier);
+#endif
