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 #define NAT_TAB_MASK 15
34 static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
35 [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) },
38 static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
39 struct tc_action *a, int ovr, int bind)
41 struct nlattr *tb[TCA_NAT_MAX + 1];
49 err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy);
53 if (tb[TCA_NAT_PARMS] == NULL)
55 parm = nla_data(tb[TCA_NAT_PARMS]);
57 if (!tcf_hash_check(parm->index, a, bind)) {
58 ret = tcf_hash_create(parm->index, est, a, sizeof(*p),
66 tcf_hash_release(a, bind);
72 spin_lock_bh(&p->tcf_lock);
73 p->old_addr = parm->old_addr;
74 p->new_addr = parm->new_addr;
76 p->flags = parm->flags;
78 p->tcf_action = parm->action;
79 spin_unlock_bh(&p->tcf_lock);
81 if (ret == ACT_P_CREATED)
87 static int tcf_nat(struct sk_buff *skb, const struct tc_action *a,
88 struct tcf_result *res)
90 struct tcf_nat *p = a->priv;
101 spin_lock(&p->tcf_lock);
103 p->tcf_tm.lastuse = jiffies;
104 old_addr = p->old_addr;
105 new_addr = p->new_addr;
107 egress = p->flags & TCA_NAT_FLAG_EGRESS;
108 action = p->tcf_action;
110 bstats_update(&p->tcf_bstats, skb);
112 spin_unlock(&p->tcf_lock);
114 if (unlikely(action == TC_ACT_SHOT))
117 noff = skb_network_offset(skb);
118 if (!pskb_may_pull(skb, sizeof(*iph) + noff))
128 if (!((old_addr ^ addr) & mask)) {
129 if (skb_try_make_writable(skb, sizeof(*iph) + noff))
133 new_addr |= addr & ~mask;
135 /* Rewrite IP header */
138 iph->saddr = new_addr;
140 iph->daddr = new_addr;
142 csum_replace4(&iph->check, addr, new_addr);
143 } else if ((iph->frag_off & htons(IP_OFFSET)) ||
144 iph->protocol != IPPROTO_ICMP) {
150 /* It would be nice to share code with stateful NAT. */
151 switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
156 if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
157 skb_try_make_writable(skb, ihl + sizeof(*tcph) + noff))
160 tcph = (void *)(skb_network_header(skb) + ihl);
161 inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr,
169 if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
170 skb_try_make_writable(skb, ihl + sizeof(*udph) + noff))
173 udph = (void *)(skb_network_header(skb) + ihl);
174 if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
175 inet_proto_csum_replace4(&udph->check, skb, addr,
178 udph->check = CSUM_MANGLED_0;
184 struct icmphdr *icmph;
186 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
189 icmph = (void *)(skb_network_header(skb) + ihl);
191 if ((icmph->type != ICMP_DEST_UNREACH) &&
192 (icmph->type != ICMP_TIME_EXCEEDED) &&
193 (icmph->type != ICMP_PARAMETERPROB))
196 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
200 icmph = (void *)(skb_network_header(skb) + ihl);
201 iph = (void *)(icmph + 1);
207 if ((old_addr ^ addr) & mask)
210 if (skb_try_make_writable(skb, ihl + sizeof(*icmph) +
211 sizeof(*iph) + noff))
214 icmph = (void *)(skb_network_header(skb) + ihl);
215 iph = (void *)(icmph + 1);
218 new_addr |= addr & ~mask;
220 /* XXX Fix up the inner checksums. */
222 iph->daddr = new_addr;
224 iph->saddr = new_addr;
226 inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
238 spin_lock(&p->tcf_lock);
239 p->tcf_qstats.drops++;
240 spin_unlock(&p->tcf_lock);
244 static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
247 unsigned char *b = skb_tail_pointer(skb);
248 struct tcf_nat *p = a->priv;
249 struct tc_nat opt = {
250 .old_addr = p->old_addr,
251 .new_addr = p->new_addr,
255 .index = p->tcf_index,
256 .action = p->tcf_action,
257 .refcnt = p->tcf_refcnt - ref,
258 .bindcnt = p->tcf_bindcnt - bind,
262 if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
263 goto nla_put_failure;
264 t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
265 t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
266 t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
267 if (nla_put(skb, TCA_NAT_TM, sizeof(t), &t))
268 goto nla_put_failure;
277 static struct tc_action_ops act_nat_ops = {
280 .owner = THIS_MODULE,
282 .dump = tcf_nat_dump,
283 .init = tcf_nat_init,
286 MODULE_DESCRIPTION("Stateless NAT actions");
287 MODULE_LICENSE("GPL");
289 static int __init nat_init_module(void)
291 return tcf_register_action(&act_nat_ops, NAT_TAB_MASK);
294 static void __exit nat_cleanup_module(void)
296 tcf_unregister_action(&act_nat_ops);
299 module_init(nat_init_module);
300 module_exit(nat_cleanup_module);