1 // SPDX-License-Identifier: GPL-2.0
3 #include <linux/types.h>
4 #include <linux/atomic.h>
5 #include <linux/inetdevice.h>
6 #include <linux/netfilter.h>
7 #include <linux/netfilter_ipv4.h>
8 #include <linux/netfilter_ipv6.h>
10 #include <net/netfilter/nf_nat_masquerade.h>
12 static DEFINE_MUTEX(masq_mutex);
13 static unsigned int masq_refcnt __read_mostly;
16 nf_nat_masquerade_ipv4(struct sk_buff *skb, unsigned int hooknum,
17 const struct nf_nat_range2 *range,
18 const struct net_device *out)
21 struct nf_conn_nat *nat;
22 enum ip_conntrack_info ctinfo;
23 struct nf_nat_range2 newrange;
24 const struct rtable *rt;
27 WARN_ON(hooknum != NF_INET_POST_ROUTING);
29 ct = nf_ct_get(skb, &ctinfo);
31 WARN_ON(!(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
32 ctinfo == IP_CT_RELATED_REPLY)));
34 /* Source address is 0.0.0.0 - locally generated packet that is
35 * probably not supposed to be masqueraded.
37 if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip == 0)
41 nh = rt_nexthop(rt, ip_hdr(skb)->daddr);
42 newsrc = inet_select_addr(out, nh, RT_SCOPE_UNIVERSE);
44 pr_info("%s ate my IP address\n", out->name);
48 nat = nf_ct_nat_ext_add(ct);
50 nat->masq_index = out->ifindex;
52 /* Transfer from original range. */
53 memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
54 memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
55 newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
56 newrange.min_addr.ip = newsrc;
57 newrange.max_addr.ip = newsrc;
58 newrange.min_proto = range->min_proto;
59 newrange.max_proto = range->max_proto;
61 /* Hand modified range to generic setup. */
62 return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
64 EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv4);
66 static int device_cmp(struct nf_conn *i, void *ifindex)
68 const struct nf_conn_nat *nat = nfct_nat(i);
72 return nat->masq_index == (int)(long)ifindex;
75 static int masq_device_event(struct notifier_block *this,
79 const struct net_device *dev = netdev_notifier_info_to_dev(ptr);
80 struct net *net = dev_net(dev);
82 if (event == NETDEV_DOWN) {
83 /* Device was downed. Search entire table for
84 * conntracks which were associated with that device,
88 nf_ct_iterate_cleanup_net(net, device_cmp,
89 (void *)(long)dev->ifindex, 0, 0);
95 static int inet_cmp(struct nf_conn *ct, void *ptr)
97 struct in_ifaddr *ifa = (struct in_ifaddr *)ptr;
98 struct net_device *dev = ifa->ifa_dev->dev;
99 struct nf_conntrack_tuple *tuple;
101 if (!device_cmp(ct, (void *)(long)dev->ifindex))
104 tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
106 return ifa->ifa_address == tuple->dst.u3.ip;
109 static int masq_inet_event(struct notifier_block *this,
113 struct in_device *idev = ((struct in_ifaddr *)ptr)->ifa_dev;
114 struct net *net = dev_net(idev->dev);
116 /* The masq_dev_notifier will catch the case of the device going
117 * down. So if the inetdev is dead and being destroyed we have
118 * no work to do. Otherwise this is an individual address removal
119 * and we have to perform the flush.
124 if (event == NETDEV_DOWN)
125 nf_ct_iterate_cleanup_net(net, inet_cmp, ptr, 0, 0);
130 static struct notifier_block masq_dev_notifier = {
131 .notifier_call = masq_device_event,
134 static struct notifier_block masq_inet_notifier = {
135 .notifier_call = masq_inet_event,
138 #if IS_ENABLED(CONFIG_IPV6)
139 static atomic_t v6_worker_count __read_mostly;
142 nat_ipv6_dev_get_saddr(struct net *net, const struct net_device *dev,
143 const struct in6_addr *daddr, unsigned int srcprefs,
144 struct in6_addr *saddr)
146 #ifdef CONFIG_IPV6_MODULE
147 const struct nf_ipv6_ops *v6_ops = nf_get_ipv6_ops();
150 return -EHOSTUNREACH;
152 return v6_ops->dev_get_saddr(net, dev, daddr, srcprefs, saddr);
154 return ipv6_dev_get_saddr(net, dev, daddr, srcprefs, saddr);
159 nf_nat_masquerade_ipv6(struct sk_buff *skb, const struct nf_nat_range2 *range,
160 const struct net_device *out)
162 enum ip_conntrack_info ctinfo;
163 struct nf_conn_nat *nat;
166 struct nf_nat_range2 newrange;
168 ct = nf_ct_get(skb, &ctinfo);
169 WARN_ON(!(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
170 ctinfo == IP_CT_RELATED_REPLY)));
172 if (nat_ipv6_dev_get_saddr(nf_ct_net(ct), out,
173 &ipv6_hdr(skb)->daddr, 0, &src) < 0)
176 nat = nf_ct_nat_ext_add(ct);
178 nat->masq_index = out->ifindex;
180 newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
181 newrange.min_addr.in6 = src;
182 newrange.max_addr.in6 = src;
183 newrange.min_proto = range->min_proto;
184 newrange.max_proto = range->max_proto;
186 return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
188 EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv6);
190 struct masq_dev_work {
191 struct work_struct work;
193 struct in6_addr addr;
197 static int inet6_cmp(struct nf_conn *ct, void *work)
199 struct masq_dev_work *w = (struct masq_dev_work *)work;
200 struct nf_conntrack_tuple *tuple;
202 if (!device_cmp(ct, (void *)(long)w->ifindex))
205 tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
207 return ipv6_addr_equal(&w->addr, &tuple->dst.u3.in6);
210 static void iterate_cleanup_work(struct work_struct *work)
212 struct masq_dev_work *w;
214 w = container_of(work, struct masq_dev_work, work);
216 nf_ct_iterate_cleanup_net(w->net, inet6_cmp, (void *)w, 0, 0);
220 atomic_dec(&v6_worker_count);
221 module_put(THIS_MODULE);
224 /* atomic notifier; can't call nf_ct_iterate_cleanup_net (it can sleep).
226 * Defer it to the system workqueue.
228 * As we can have 'a lot' of inet_events (depending on amount of ipv6
229 * addresses being deleted), we also need to limit work item queue.
231 static int masq_inet6_event(struct notifier_block *this,
232 unsigned long event, void *ptr)
234 struct inet6_ifaddr *ifa = ptr;
235 const struct net_device *dev;
236 struct masq_dev_work *w;
239 if (event != NETDEV_DOWN || atomic_read(&v6_worker_count) >= 16)
242 dev = ifa->idev->dev;
243 net = maybe_get_net(dev_net(dev));
247 if (!try_module_get(THIS_MODULE))
250 w = kmalloc(sizeof(*w), GFP_ATOMIC);
252 atomic_inc(&v6_worker_count);
254 INIT_WORK(&w->work, iterate_cleanup_work);
255 w->ifindex = dev->ifindex;
258 schedule_work(&w->work);
263 module_put(THIS_MODULE);
269 static struct notifier_block masq_inet6_notifier = {
270 .notifier_call = masq_inet6_event,
273 static int nf_nat_masquerade_ipv6_register_notifier(void)
275 return register_inet6addr_notifier(&masq_inet6_notifier);
278 static inline int nf_nat_masquerade_ipv6_register_notifier(void) { return 0; }
281 int nf_nat_masquerade_inet_register_notifiers(void)
285 mutex_lock(&masq_mutex);
286 if (WARN_ON_ONCE(masq_refcnt == UINT_MAX)) {
291 /* check if the notifier was already set */
292 if (++masq_refcnt > 1)
295 /* Register for device down reports */
296 ret = register_netdevice_notifier(&masq_dev_notifier);
299 /* Register IP address change reports */
300 ret = register_inetaddr_notifier(&masq_inet_notifier);
304 ret = nf_nat_masquerade_ipv6_register_notifier();
308 mutex_unlock(&masq_mutex);
311 unregister_inetaddr_notifier(&masq_inet_notifier);
313 unregister_netdevice_notifier(&masq_dev_notifier);
317 mutex_unlock(&masq_mutex);
320 EXPORT_SYMBOL_GPL(nf_nat_masquerade_inet_register_notifiers);
322 void nf_nat_masquerade_inet_unregister_notifiers(void)
324 mutex_lock(&masq_mutex);
325 /* check if the notifiers still have clients */
326 if (--masq_refcnt > 0)
329 unregister_netdevice_notifier(&masq_dev_notifier);
330 unregister_inetaddr_notifier(&masq_inet_notifier);
331 #if IS_ENABLED(CONFIG_IPV6)
332 unregister_inet6addr_notifier(&masq_inet6_notifier);
335 mutex_unlock(&masq_mutex);
337 EXPORT_SYMBOL_GPL(nf_nat_masquerade_inet_unregister_notifiers);