2 * Stateless NAT actions
4 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License as published by the Free
8 * Software Foundation; either version 2 of the License, or (at your option)
12 #include <linux/errno.h>
13 #include <linux/init.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/netfilter.h>
17 #include <linux/rtnetlink.h>
18 #include <linux/skbuff.h>
19 #include <linux/slab.h>
20 #include <linux/spinlock.h>
21 #include <linux/string.h>
22 #include <linux/tc_act/tc_nat.h>
23 #include <net/act_api.h>
26 #include <net/netlink.h>
27 #include <net/tc_act/tc_nat.h>
32 static unsigned int nat_net_id;
33 static struct tc_action_ops act_nat_ops;
35 static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
36 [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) },
39 static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
40 struct tc_action **a, int ovr, int bind,
41 bool rtnl_held, struct netlink_ext_ack *extack)
43 struct tc_action_net *tn = net_generic(net, nat_net_id);
44 struct nlattr *tb[TCA_NAT_MAX + 1];
52 err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy, NULL);
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);
81 spin_lock_bh(&p->tcf_lock);
82 p->old_addr = parm->old_addr;
83 p->new_addr = parm->new_addr;
85 p->flags = parm->flags;
87 p->tcf_action = parm->action;
88 spin_unlock_bh(&p->tcf_lock);
90 if (ret == ACT_P_CREATED)
91 tcf_idr_insert(tn, *a);
96 static int tcf_nat_act(struct sk_buff *skb, const struct tc_action *a,
97 struct tcf_result *res)
99 struct tcf_nat *p = to_tcf_nat(a);
110 spin_lock(&p->tcf_lock);
112 tcf_lastuse_update(&p->tcf_tm);
113 old_addr = p->old_addr;
114 new_addr = p->new_addr;
116 egress = p->flags & TCA_NAT_FLAG_EGRESS;
117 action = p->tcf_action;
119 bstats_update(&p->tcf_bstats, skb);
121 spin_unlock(&p->tcf_lock);
123 if (unlikely(action == TC_ACT_SHOT))
126 noff = skb_network_offset(skb);
127 if (!pskb_may_pull(skb, sizeof(*iph) + noff))
137 if (!((old_addr ^ addr) & mask)) {
138 if (skb_try_make_writable(skb, sizeof(*iph) + noff))
142 new_addr |= addr & ~mask;
144 /* Rewrite IP header */
147 iph->saddr = new_addr;
149 iph->daddr = new_addr;
151 csum_replace4(&iph->check, addr, new_addr);
152 } else if ((iph->frag_off & htons(IP_OFFSET)) ||
153 iph->protocol != IPPROTO_ICMP) {
159 /* It would be nice to share code with stateful NAT. */
160 switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
165 if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
166 skb_try_make_writable(skb, ihl + sizeof(*tcph) + noff))
169 tcph = (void *)(skb_network_header(skb) + ihl);
170 inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr,
178 if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
179 skb_try_make_writable(skb, ihl + sizeof(*udph) + noff))
182 udph = (void *)(skb_network_header(skb) + ihl);
183 if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
184 inet_proto_csum_replace4(&udph->check, skb, addr,
187 udph->check = CSUM_MANGLED_0;
193 struct icmphdr *icmph;
195 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
198 icmph = (void *)(skb_network_header(skb) + ihl);
200 if ((icmph->type != ICMP_DEST_UNREACH) &&
201 (icmph->type != ICMP_TIME_EXCEEDED) &&
202 (icmph->type != ICMP_PARAMETERPROB))
205 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
209 icmph = (void *)(skb_network_header(skb) + ihl);
210 iph = (void *)(icmph + 1);
216 if ((old_addr ^ addr) & mask)
219 if (skb_try_make_writable(skb, ihl + sizeof(*icmph) +
220 sizeof(*iph) + noff))
223 icmph = (void *)(skb_network_header(skb) + ihl);
224 iph = (void *)(icmph + 1);
227 new_addr |= addr & ~mask;
229 /* XXX Fix up the inner checksums. */
231 iph->daddr = new_addr;
233 iph->saddr = new_addr;
235 inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
247 spin_lock(&p->tcf_lock);
248 p->tcf_qstats.drops++;
249 spin_unlock(&p->tcf_lock);
253 static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
256 unsigned char *b = skb_tail_pointer(skb);
257 struct tcf_nat *p = to_tcf_nat(a);
258 struct tc_nat opt = {
259 .index = p->tcf_index,
260 .refcnt = refcount_read(&p->tcf_refcnt) - ref,
261 .bindcnt = atomic_read(&p->tcf_bindcnt) - bind,
265 spin_lock_bh(&p->tcf_lock);
266 opt.old_addr = p->old_addr;
267 opt.new_addr = p->new_addr;
269 opt.flags = p->flags;
270 opt.action = p->tcf_action;
272 if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
273 goto nla_put_failure;
275 tcf_tm_dump(&t, &p->tcf_tm);
276 if (nla_put_64bit(skb, TCA_NAT_TM, sizeof(t), &t, TCA_NAT_PAD))
277 goto nla_put_failure;
278 spin_unlock_bh(&p->tcf_lock);
283 spin_unlock_bh(&p->tcf_lock);
288 static int tcf_nat_walker(struct net *net, struct sk_buff *skb,
289 struct netlink_callback *cb, int type,
290 const struct tc_action_ops *ops,
291 struct netlink_ext_ack *extack)
293 struct tc_action_net *tn = net_generic(net, nat_net_id);
295 return tcf_generic_walker(tn, skb, cb, type, ops, extack);
298 static int tcf_nat_search(struct net *net, struct tc_action **a, u32 index)
300 struct tc_action_net *tn = net_generic(net, nat_net_id);
302 return tcf_idr_search(tn, a, index);
305 static struct tc_action_ops act_nat_ops = {
308 .owner = THIS_MODULE,
310 .dump = tcf_nat_dump,
311 .init = tcf_nat_init,
312 .walk = tcf_nat_walker,
313 .lookup = tcf_nat_search,
314 .size = sizeof(struct tcf_nat),
317 static __net_init int nat_init_net(struct net *net)
319 struct tc_action_net *tn = net_generic(net, nat_net_id);
321 return tc_action_net_init(tn, &act_nat_ops);
324 static void __net_exit nat_exit_net(struct list_head *net_list)
326 tc_action_net_exit(net_list, nat_net_id);
329 static struct pernet_operations nat_net_ops = {
330 .init = nat_init_net,
331 .exit_batch = nat_exit_net,
333 .size = sizeof(struct tc_action_net),
336 MODULE_DESCRIPTION("Stateless NAT actions");
337 MODULE_LICENSE("GPL");
339 static int __init nat_init_module(void)
341 return tcf_register_action(&act_nat_ops, &nat_net_ops);
344 static void __exit nat_cleanup_module(void)
346 tcf_unregister_action(&act_nat_ops, &nat_net_ops);
349 module_init(nat_init_module);
350 module_exit(nat_cleanup_module);