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, int ovr, int bind,
38 bool rtnl_held, struct tcf_proto *tp,
39 struct netlink_ext_ack *extack)
41 struct tc_action_net *tn = net_generic(net, nat_net_id);
42 struct nlattr *tb[TCA_NAT_MAX + 1];
43 struct tcf_chain *goto_ch = NULL;
51 err = nla_parse_nested_deprecated(tb, TCA_NAT_MAX, nla, nat_policy,
56 if (tb[TCA_NAT_PARMS] == NULL)
58 parm = nla_data(tb[TCA_NAT_PARMS]);
60 err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
62 ret = tcf_idr_create(tn, parm->index, est, a,
63 &act_nat_ops, bind, false);
65 tcf_idr_cleanup(tn, parm->index);
73 tcf_idr_release(*a, bind);
79 err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
84 spin_lock_bh(&p->tcf_lock);
85 p->old_addr = parm->old_addr;
86 p->new_addr = parm->new_addr;
88 p->flags = parm->flags;
90 goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
91 spin_unlock_bh(&p->tcf_lock);
93 tcf_chain_put_by_act(goto_ch);
95 if (ret == ACT_P_CREATED)
96 tcf_idr_insert(tn, *a);
100 tcf_idr_release(*a, bind);
104 static int tcf_nat_act(struct sk_buff *skb, const struct tc_action *a,
105 struct tcf_result *res)
107 struct tcf_nat *p = to_tcf_nat(a);
118 spin_lock(&p->tcf_lock);
120 tcf_lastuse_update(&p->tcf_tm);
121 old_addr = p->old_addr;
122 new_addr = p->new_addr;
124 egress = p->flags & TCA_NAT_FLAG_EGRESS;
125 action = p->tcf_action;
127 bstats_update(&p->tcf_bstats, skb);
129 spin_unlock(&p->tcf_lock);
131 if (unlikely(action == TC_ACT_SHOT))
134 noff = skb_network_offset(skb);
135 if (!pskb_may_pull(skb, sizeof(*iph) + noff))
145 if (!((old_addr ^ addr) & mask)) {
146 if (skb_try_make_writable(skb, sizeof(*iph) + noff))
150 new_addr |= addr & ~mask;
152 /* Rewrite IP header */
155 iph->saddr = new_addr;
157 iph->daddr = new_addr;
159 csum_replace4(&iph->check, addr, new_addr);
160 } else if ((iph->frag_off & htons(IP_OFFSET)) ||
161 iph->protocol != IPPROTO_ICMP) {
167 /* It would be nice to share code with stateful NAT. */
168 switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
173 if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
174 skb_try_make_writable(skb, ihl + sizeof(*tcph) + noff))
177 tcph = (void *)(skb_network_header(skb) + ihl);
178 inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr,
186 if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
187 skb_try_make_writable(skb, ihl + sizeof(*udph) + noff))
190 udph = (void *)(skb_network_header(skb) + ihl);
191 if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
192 inet_proto_csum_replace4(&udph->check, skb, addr,
195 udph->check = CSUM_MANGLED_0;
201 struct icmphdr *icmph;
203 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
206 icmph = (void *)(skb_network_header(skb) + ihl);
208 if ((icmph->type != ICMP_DEST_UNREACH) &&
209 (icmph->type != ICMP_TIME_EXCEEDED) &&
210 (icmph->type != ICMP_PARAMETERPROB))
213 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
217 icmph = (void *)(skb_network_header(skb) + ihl);
218 iph = (void *)(icmph + 1);
224 if ((old_addr ^ addr) & mask)
227 if (skb_try_make_writable(skb, ihl + sizeof(*icmph) +
228 sizeof(*iph) + noff))
231 icmph = (void *)(skb_network_header(skb) + ihl);
232 iph = (void *)(icmph + 1);
235 new_addr |= addr & ~mask;
237 /* XXX Fix up the inner checksums. */
239 iph->daddr = new_addr;
241 iph->saddr = new_addr;
243 inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
255 spin_lock(&p->tcf_lock);
256 p->tcf_qstats.drops++;
257 spin_unlock(&p->tcf_lock);
261 static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
264 unsigned char *b = skb_tail_pointer(skb);
265 struct tcf_nat *p = to_tcf_nat(a);
266 struct tc_nat opt = {
267 .index = p->tcf_index,
268 .refcnt = refcount_read(&p->tcf_refcnt) - ref,
269 .bindcnt = atomic_read(&p->tcf_bindcnt) - bind,
273 spin_lock_bh(&p->tcf_lock);
274 opt.old_addr = p->old_addr;
275 opt.new_addr = p->new_addr;
277 opt.flags = p->flags;
278 opt.action = p->tcf_action;
280 if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
281 goto nla_put_failure;
283 tcf_tm_dump(&t, &p->tcf_tm);
284 if (nla_put_64bit(skb, TCA_NAT_TM, sizeof(t), &t, TCA_NAT_PAD))
285 goto nla_put_failure;
286 spin_unlock_bh(&p->tcf_lock);
291 spin_unlock_bh(&p->tcf_lock);
296 static int tcf_nat_walker(struct net *net, struct sk_buff *skb,
297 struct netlink_callback *cb, int type,
298 const struct tc_action_ops *ops,
299 struct netlink_ext_ack *extack)
301 struct tc_action_net *tn = net_generic(net, nat_net_id);
303 return tcf_generic_walker(tn, skb, cb, type, ops, extack);
306 static int tcf_nat_search(struct net *net, struct tc_action **a, u32 index)
308 struct tc_action_net *tn = net_generic(net, nat_net_id);
310 return tcf_idr_search(tn, a, index);
313 static struct tc_action_ops act_nat_ops = {
316 .owner = THIS_MODULE,
318 .dump = tcf_nat_dump,
319 .init = tcf_nat_init,
320 .walk = tcf_nat_walker,
321 .lookup = tcf_nat_search,
322 .size = sizeof(struct tcf_nat),
325 static __net_init int nat_init_net(struct net *net)
327 struct tc_action_net *tn = net_generic(net, nat_net_id);
329 return tc_action_net_init(tn, &act_nat_ops);
332 static void __net_exit nat_exit_net(struct list_head *net_list)
334 tc_action_net_exit(net_list, nat_net_id);
337 static struct pernet_operations nat_net_ops = {
338 .init = nat_init_net,
339 .exit_batch = nat_exit_net,
341 .size = sizeof(struct tc_action_net),
344 MODULE_DESCRIPTION("Stateless NAT actions");
345 MODULE_LICENSE("GPL");
347 static int __init nat_init_module(void)
349 return tcf_register_action(&act_nat_ops, &nat_net_ops);
352 static void __exit nat_cleanup_module(void)
354 tcf_unregister_action(&act_nat_ops, &nat_net_ops);
357 module_init(nat_init_module);
358 module_exit(nat_cleanup_module);