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 struct tcf_hashinfo nat_hash_info;
36 static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
37 [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) },
40 static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
41 struct tc_action *a, int ovr, int bind)
43 struct nlattr *tb[TCA_NAT_MAX + 1];
47 struct tcf_common *pc;
52 err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy);
56 if (tb[TCA_NAT_PARMS] == NULL)
58 parm = nla_data(tb[TCA_NAT_PARMS]);
60 pc = tcf_hash_check(parm->index, a, bind, &nat_hash_info);
62 pc = tcf_hash_create(parm->index, est, a, sizeof(*p), bind,
70 tcf_hash_release(pc, bind, &nat_hash_info);
76 spin_lock_bh(&p->tcf_lock);
77 p->old_addr = parm->old_addr;
78 p->new_addr = parm->new_addr;
80 p->flags = parm->flags;
82 p->tcf_action = parm->action;
83 spin_unlock_bh(&p->tcf_lock);
85 if (ret == ACT_P_CREATED)
86 tcf_hash_insert(pc, &nat_hash_info);
91 static int tcf_nat_cleanup(struct tc_action *a, int bind)
93 struct tcf_nat *p = a->priv;
95 return tcf_hash_release(&p->common, bind, &nat_hash_info);
98 static int tcf_nat(struct sk_buff *skb, const struct tc_action *a,
99 struct tcf_result *res)
101 struct tcf_nat *p = a->priv;
112 spin_lock(&p->tcf_lock);
114 p->tcf_tm.lastuse = jiffies;
115 old_addr = p->old_addr;
116 new_addr = p->new_addr;
118 egress = p->flags & TCA_NAT_FLAG_EGRESS;
119 action = p->tcf_action;
121 bstats_update(&p->tcf_bstats, skb);
123 spin_unlock(&p->tcf_lock);
125 if (unlikely(action == TC_ACT_SHOT))
128 noff = skb_network_offset(skb);
129 if (!pskb_may_pull(skb, sizeof(*iph) + noff))
139 if (!((old_addr ^ addr) & mask)) {
140 if (skb_cloned(skb) &&
141 !skb_clone_writable(skb, sizeof(*iph) + noff) &&
142 pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
146 new_addr |= addr & ~mask;
148 /* Rewrite IP header */
151 iph->saddr = new_addr;
153 iph->daddr = new_addr;
155 csum_replace4(&iph->check, addr, new_addr);
156 } else if ((iph->frag_off & htons(IP_OFFSET)) ||
157 iph->protocol != IPPROTO_ICMP) {
163 /* It would be nice to share code with stateful NAT. */
164 switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
169 if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
171 !skb_clone_writable(skb, ihl + sizeof(*tcph) + noff) &&
172 pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
175 tcph = (void *)(skb_network_header(skb) + ihl);
176 inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, 1);
183 if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
185 !skb_clone_writable(skb, ihl + sizeof(*udph) + noff) &&
186 pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
189 udph = (void *)(skb_network_header(skb) + ihl);
190 if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
191 inet_proto_csum_replace4(&udph->check, skb, addr,
194 udph->check = CSUM_MANGLED_0;
200 struct icmphdr *icmph;
202 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
205 icmph = (void *)(skb_network_header(skb) + ihl);
207 if ((icmph->type != ICMP_DEST_UNREACH) &&
208 (icmph->type != ICMP_TIME_EXCEEDED) &&
209 (icmph->type != ICMP_PARAMETERPROB))
212 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
216 icmph = (void *)(skb_network_header(skb) + ihl);
217 iph = (void *)(icmph + 1);
223 if ((old_addr ^ addr) & mask)
226 if (skb_cloned(skb) &&
227 !skb_clone_writable(skb, ihl + sizeof(*icmph) +
228 sizeof(*iph) + noff) &&
229 pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
232 icmph = (void *)(skb_network_header(skb) + ihl);
233 iph = (void *)(icmph + 1);
236 new_addr |= addr & ~mask;
238 /* XXX Fix up the inner checksums. */
240 iph->daddr = new_addr;
242 iph->saddr = new_addr;
244 inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
256 spin_lock(&p->tcf_lock);
257 p->tcf_qstats.drops++;
258 spin_unlock(&p->tcf_lock);
262 static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
265 unsigned char *b = skb_tail_pointer(skb);
266 struct tcf_nat *p = a->priv;
267 struct tc_nat opt = {
268 .old_addr = p->old_addr,
269 .new_addr = p->new_addr,
273 .index = p->tcf_index,
274 .action = p->tcf_action,
275 .refcnt = p->tcf_refcnt - ref,
276 .bindcnt = p->tcf_bindcnt - bind,
280 if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
281 goto nla_put_failure;
282 t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
283 t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
284 t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
285 if (nla_put(skb, TCA_NAT_TM, sizeof(t), &t))
286 goto nla_put_failure;
295 static struct tc_action_ops act_nat_ops = {
297 .hinfo = &nat_hash_info,
299 .capab = TCA_CAP_NONE,
300 .owner = THIS_MODULE,
302 .dump = tcf_nat_dump,
303 .cleanup = tcf_nat_cleanup,
304 .init = tcf_nat_init,
307 MODULE_DESCRIPTION("Stateless NAT actions");
308 MODULE_LICENSE("GPL");
310 static int __init nat_init_module(void)
312 int err = tcf_hashinfo_init(&nat_hash_info, NAT_TAB_MASK);
315 return tcf_register_action(&act_nat_ops);
318 static void __exit nat_cleanup_module(void)
320 tcf_unregister_action(&act_nat_ops);
321 tcf_hashinfo_destroy(&nat_hash_info);
324 module_init(nat_init_module);
325 module_exit(nat_cleanup_module);