1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Stateless NAT actions
5 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
8 #include <linux/errno.h>
9 #include <linux/init.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/netfilter.h>
13 #include <linux/rtnetlink.h>
14 #include <linux/skbuff.h>
15 #include <linux/slab.h>
16 #include <linux/spinlock.h>
17 #include <linux/string.h>
18 #include <linux/tc_act/tc_nat.h>
19 #include <net/act_api.h>
20 #include <net/pkt_cls.h>
23 #include <net/netlink.h>
24 #include <net/tc_act/tc_nat.h>
29 static unsigned int nat_net_id;
30 static struct tc_action_ops act_nat_ops;
32 static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
33 [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) },
36 static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
37 struct tc_action **a, struct tcf_proto *tp,
38 u32 flags, struct netlink_ext_ack *extack)
40 struct tc_action_net *tn = net_generic(net, nat_net_id);
41 bool bind = flags & TCA_ACT_FLAGS_BIND;
42 struct nlattr *tb[TCA_NAT_MAX + 1];
43 struct tcf_chain *goto_ch = NULL;
52 err = nla_parse_nested_deprecated(tb, TCA_NAT_MAX, nla, nat_policy,
57 if (tb[TCA_NAT_PARMS] == NULL)
59 parm = nla_data(tb[TCA_NAT_PARMS]);
61 err = tcf_idr_check_alloc(tn, &index, a, bind);
63 ret = tcf_idr_create(tn, index, est, a,
64 &act_nat_ops, bind, false, 0);
66 tcf_idr_cleanup(tn, index);
73 if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
74 tcf_idr_release(*a, bind);
80 err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
85 spin_lock_bh(&p->tcf_lock);
86 p->old_addr = parm->old_addr;
87 p->new_addr = parm->new_addr;
89 p->flags = parm->flags;
91 goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
92 spin_unlock_bh(&p->tcf_lock);
94 tcf_chain_put_by_act(goto_ch);
98 tcf_idr_release(*a, bind);
102 static int tcf_nat_act(struct sk_buff *skb, const struct tc_action *a,
103 struct tcf_result *res)
105 struct tcf_nat *p = to_tcf_nat(a);
116 spin_lock(&p->tcf_lock);
118 tcf_lastuse_update(&p->tcf_tm);
119 old_addr = p->old_addr;
120 new_addr = p->new_addr;
122 egress = p->flags & TCA_NAT_FLAG_EGRESS;
123 action = p->tcf_action;
125 bstats_update(&p->tcf_bstats, skb);
127 spin_unlock(&p->tcf_lock);
129 if (unlikely(action == TC_ACT_SHOT))
132 noff = skb_network_offset(skb);
133 if (!pskb_may_pull(skb, sizeof(*iph) + noff))
143 if (!((old_addr ^ addr) & mask)) {
144 if (skb_try_make_writable(skb, sizeof(*iph) + noff))
148 new_addr |= addr & ~mask;
150 /* Rewrite IP header */
153 iph->saddr = new_addr;
155 iph->daddr = new_addr;
157 csum_replace4(&iph->check, addr, new_addr);
158 } else if ((iph->frag_off & htons(IP_OFFSET)) ||
159 iph->protocol != IPPROTO_ICMP) {
165 /* It would be nice to share code with stateful NAT. */
166 switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
171 if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
172 skb_try_make_writable(skb, ihl + sizeof(*tcph) + noff))
175 tcph = (void *)(skb_network_header(skb) + ihl);
176 inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr,
184 if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
185 skb_try_make_writable(skb, ihl + sizeof(*udph) + noff))
188 udph = (void *)(skb_network_header(skb) + ihl);
189 if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
190 inet_proto_csum_replace4(&udph->check, skb, addr,
193 udph->check = CSUM_MANGLED_0;
199 struct icmphdr *icmph;
201 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
204 icmph = (void *)(skb_network_header(skb) + ihl);
206 if (!icmp_is_err(icmph->type))
209 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
213 icmph = (void *)(skb_network_header(skb) + ihl);
214 iph = (void *)(icmph + 1);
220 if ((old_addr ^ addr) & mask)
223 if (skb_try_make_writable(skb, ihl + sizeof(*icmph) +
224 sizeof(*iph) + noff))
227 icmph = (void *)(skb_network_header(skb) + ihl);
228 iph = (void *)(icmph + 1);
231 new_addr |= addr & ~mask;
233 /* XXX Fix up the inner checksums. */
235 iph->daddr = new_addr;
237 iph->saddr = new_addr;
239 inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
251 spin_lock(&p->tcf_lock);
252 p->tcf_qstats.drops++;
253 spin_unlock(&p->tcf_lock);
257 static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
260 unsigned char *b = skb_tail_pointer(skb);
261 struct tcf_nat *p = to_tcf_nat(a);
262 struct tc_nat opt = {
263 .index = p->tcf_index,
264 .refcnt = refcount_read(&p->tcf_refcnt) - ref,
265 .bindcnt = atomic_read(&p->tcf_bindcnt) - bind,
269 spin_lock_bh(&p->tcf_lock);
270 opt.old_addr = p->old_addr;
271 opt.new_addr = p->new_addr;
273 opt.flags = p->flags;
274 opt.action = p->tcf_action;
276 if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
277 goto nla_put_failure;
279 tcf_tm_dump(&t, &p->tcf_tm);
280 if (nla_put_64bit(skb, TCA_NAT_TM, sizeof(t), &t, TCA_NAT_PAD))
281 goto nla_put_failure;
282 spin_unlock_bh(&p->tcf_lock);
287 spin_unlock_bh(&p->tcf_lock);
292 static int tcf_nat_walker(struct net *net, struct sk_buff *skb,
293 struct netlink_callback *cb, int type,
294 const struct tc_action_ops *ops,
295 struct netlink_ext_ack *extack)
297 struct tc_action_net *tn = net_generic(net, nat_net_id);
299 return tcf_generic_walker(tn, skb, cb, type, ops, extack);
302 static int tcf_nat_search(struct net *net, struct tc_action **a, u32 index)
304 struct tc_action_net *tn = net_generic(net, nat_net_id);
306 return tcf_idr_search(tn, a, index);
309 static struct tc_action_ops act_nat_ops = {
312 .owner = THIS_MODULE,
314 .dump = tcf_nat_dump,
315 .init = tcf_nat_init,
316 .walk = tcf_nat_walker,
317 .lookup = tcf_nat_search,
318 .size = sizeof(struct tcf_nat),
321 static __net_init int nat_init_net(struct net *net)
323 struct tc_action_net *tn = net_generic(net, nat_net_id);
325 return tc_action_net_init(net, tn, &act_nat_ops);
328 static void __net_exit nat_exit_net(struct list_head *net_list)
330 tc_action_net_exit(net_list, nat_net_id);
333 static struct pernet_operations nat_net_ops = {
334 .init = nat_init_net,
335 .exit_batch = nat_exit_net,
337 .size = sizeof(struct tc_action_net),
340 MODULE_DESCRIPTION("Stateless NAT actions");
341 MODULE_LICENSE("GPL");
343 static int __init nat_init_module(void)
345 return tcf_register_action(&act_nat_ops, &nat_net_ops);
348 static void __exit nat_cleanup_module(void)
350 tcf_unregister_action(&act_nat_ops, &nat_net_ops);
353 module_init(nat_init_module);
354 module_exit(nat_cleanup_module);