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
33 static u32 nat_idx_gen;
35 static struct tcf_hashinfo nat_hash_info;
37 static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
38 [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) },
41 static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
42 struct tc_action *a, int ovr, int bind)
44 struct nlattr *tb[TCA_NAT_MAX + 1];
48 struct tcf_common *pc;
53 err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy);
57 if (tb[TCA_NAT_PARMS] == NULL)
59 parm = nla_data(tb[TCA_NAT_PARMS]);
61 pc = tcf_hash_check(parm->index, a, bind, &nat_hash_info);
63 pc = tcf_hash_create(parm->index, est, a, sizeof(*p), bind,
64 &nat_idx_gen, &nat_hash_info);
72 tcf_hash_release(pc, bind, &nat_hash_info);
77 spin_lock_bh(&p->tcf_lock);
78 p->old_addr = parm->old_addr;
79 p->new_addr = parm->new_addr;
81 p->flags = parm->flags;
83 p->tcf_action = parm->action;
84 spin_unlock_bh(&p->tcf_lock);
86 if (ret == ACT_P_CREATED)
87 tcf_hash_insert(pc, &nat_hash_info);
92 static int tcf_nat_cleanup(struct tc_action *a, int bind)
94 struct tcf_nat *p = a->priv;
96 return tcf_hash_release(&p->common, bind, &nat_hash_info);
99 static int tcf_nat(struct sk_buff *skb, const struct tc_action *a,
100 struct tcf_result *res)
102 struct tcf_nat *p = a->priv;
113 spin_lock(&p->tcf_lock);
115 p->tcf_tm.lastuse = jiffies;
116 old_addr = p->old_addr;
117 new_addr = p->new_addr;
119 egress = p->flags & TCA_NAT_FLAG_EGRESS;
120 action = p->tcf_action;
122 bstats_update(&p->tcf_bstats, skb);
124 spin_unlock(&p->tcf_lock);
126 if (unlikely(action == TC_ACT_SHOT))
129 noff = skb_network_offset(skb);
130 if (!pskb_may_pull(skb, sizeof(*iph) + noff))
140 if (!((old_addr ^ addr) & mask)) {
141 if (skb_cloned(skb) &&
142 !skb_clone_writable(skb, sizeof(*iph) + noff) &&
143 pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
147 new_addr |= addr & ~mask;
149 /* Rewrite IP header */
152 iph->saddr = new_addr;
154 iph->daddr = new_addr;
156 csum_replace4(&iph->check, addr, new_addr);
157 } else if ((iph->frag_off & htons(IP_OFFSET)) ||
158 iph->protocol != IPPROTO_ICMP) {
164 /* It would be nice to share code with stateful NAT. */
165 switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
170 if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
172 !skb_clone_writable(skb, ihl + sizeof(*tcph) + noff) &&
173 pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
176 tcph = (void *)(skb_network_header(skb) + ihl);
177 inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, 1);
184 if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
186 !skb_clone_writable(skb, ihl + sizeof(*udph) + noff) &&
187 pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
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_cloned(skb) &&
228 !skb_clone_writable(skb, ihl + sizeof(*icmph) +
229 sizeof(*iph) + noff) &&
230 pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
233 icmph = (void *)(skb_network_header(skb) + ihl);
234 iph = (void *)(icmph + 1);
237 new_addr |= addr & ~mask;
239 /* XXX Fix up the inner checksums. */
241 iph->daddr = new_addr;
243 iph->saddr = new_addr;
245 inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
257 spin_lock(&p->tcf_lock);
258 p->tcf_qstats.drops++;
259 spin_unlock(&p->tcf_lock);
263 static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
266 unsigned char *b = skb_tail_pointer(skb);
267 struct tcf_nat *p = a->priv;
268 struct tc_nat opt = {
269 .old_addr = p->old_addr,
270 .new_addr = p->new_addr,
274 .index = p->tcf_index,
275 .action = p->tcf_action,
276 .refcnt = p->tcf_refcnt - ref,
277 .bindcnt = p->tcf_bindcnt - bind,
281 if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
282 goto nla_put_failure;
283 t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
284 t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
285 t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
286 if (nla_put(skb, TCA_NAT_TM, sizeof(t), &t))
287 goto nla_put_failure;
296 static struct tc_action_ops act_nat_ops = {
298 .hinfo = &nat_hash_info,
300 .capab = TCA_CAP_NONE,
301 .owner = THIS_MODULE,
303 .dump = tcf_nat_dump,
304 .cleanup = tcf_nat_cleanup,
305 .init = tcf_nat_init,
308 MODULE_DESCRIPTION("Stateless NAT actions");
309 MODULE_LICENSE("GPL");
311 static int __init nat_init_module(void)
313 int err = tcf_hashinfo_init(&nat_hash_info, NAT_TAB_MASK);
316 return tcf_register_action(&act_nat_ops);
319 static void __exit nat_cleanup_module(void)
321 tcf_unregister_action(&act_nat_ops);
322 tcf_hashinfo_destroy(&nat_hash_info);
325 module_init(nat_init_module);
326 module_exit(nat_cleanup_module);