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];
51 err
= nla_parse_nested(tb
, TCA_NAT_MAX
, nla
, nat_policy
);
55 if (tb
[TCA_NAT_PARMS
] == NULL
)
57 parm
= nla_data(tb
[TCA_NAT_PARMS
]);
59 if (!tcf_hash_check(parm
->index
, a
, bind
)) {
60 ret
= tcf_hash_create(parm
->index
, est
, a
, sizeof(*p
), bind
);
67 tcf_hash_release(a
, bind
);
73 spin_lock_bh(&p
->tcf_lock
);
74 p
->old_addr
= parm
->old_addr
;
75 p
->new_addr
= parm
->new_addr
;
77 p
->flags
= parm
->flags
;
79 p
->tcf_action
= parm
->action
;
80 spin_unlock_bh(&p
->tcf_lock
);
82 if (ret
== ACT_P_CREATED
)
88 static int tcf_nat(struct sk_buff
*skb
, const struct tc_action
*a
,
89 struct tcf_result
*res
)
91 struct tcf_nat
*p
= a
->priv
;
102 spin_lock(&p
->tcf_lock
);
104 p
->tcf_tm
.lastuse
= jiffies
;
105 old_addr
= p
->old_addr
;
106 new_addr
= p
->new_addr
;
108 egress
= p
->flags
& TCA_NAT_FLAG_EGRESS
;
109 action
= p
->tcf_action
;
111 bstats_update(&p
->tcf_bstats
, skb
);
113 spin_unlock(&p
->tcf_lock
);
115 if (unlikely(action
== TC_ACT_SHOT
))
118 noff
= skb_network_offset(skb
);
119 if (!pskb_may_pull(skb
, sizeof(*iph
) + noff
))
129 if (!((old_addr
^ addr
) & mask
)) {
130 if (skb_cloned(skb
) &&
131 !skb_clone_writable(skb
, sizeof(*iph
) + noff
) &&
132 pskb_expand_head(skb
, 0, 0, GFP_ATOMIC
))
136 new_addr
|= addr
& ~mask
;
138 /* Rewrite IP header */
141 iph
->saddr
= new_addr
;
143 iph
->daddr
= new_addr
;
145 csum_replace4(&iph
->check
, addr
, new_addr
);
146 } else if ((iph
->frag_off
& htons(IP_OFFSET
)) ||
147 iph
->protocol
!= IPPROTO_ICMP
) {
153 /* It would be nice to share code with stateful NAT. */
154 switch (iph
->frag_off
& htons(IP_OFFSET
) ? 0 : iph
->protocol
) {
159 if (!pskb_may_pull(skb
, ihl
+ sizeof(*tcph
) + noff
) ||
161 !skb_clone_writable(skb
, ihl
+ sizeof(*tcph
) + noff
) &&
162 pskb_expand_head(skb
, 0, 0, GFP_ATOMIC
)))
165 tcph
= (void *)(skb_network_header(skb
) + ihl
);
166 inet_proto_csum_replace4(&tcph
->check
, skb
, addr
, new_addr
, 1);
173 if (!pskb_may_pull(skb
, ihl
+ sizeof(*udph
) + noff
) ||
175 !skb_clone_writable(skb
, ihl
+ sizeof(*udph
) + noff
) &&
176 pskb_expand_head(skb
, 0, 0, GFP_ATOMIC
)))
179 udph
= (void *)(skb_network_header(skb
) + ihl
);
180 if (udph
->check
|| skb
->ip_summed
== CHECKSUM_PARTIAL
) {
181 inet_proto_csum_replace4(&udph
->check
, skb
, addr
,
184 udph
->check
= CSUM_MANGLED_0
;
190 struct icmphdr
*icmph
;
192 if (!pskb_may_pull(skb
, ihl
+ sizeof(*icmph
) + noff
))
195 icmph
= (void *)(skb_network_header(skb
) + ihl
);
197 if ((icmph
->type
!= ICMP_DEST_UNREACH
) &&
198 (icmph
->type
!= ICMP_TIME_EXCEEDED
) &&
199 (icmph
->type
!= ICMP_PARAMETERPROB
))
202 if (!pskb_may_pull(skb
, ihl
+ sizeof(*icmph
) + sizeof(*iph
) +
206 icmph
= (void *)(skb_network_header(skb
) + ihl
);
207 iph
= (void *)(icmph
+ 1);
213 if ((old_addr
^ addr
) & mask
)
216 if (skb_cloned(skb
) &&
217 !skb_clone_writable(skb
, ihl
+ sizeof(*icmph
) +
218 sizeof(*iph
) + noff
) &&
219 pskb_expand_head(skb
, 0, 0, GFP_ATOMIC
))
222 icmph
= (void *)(skb_network_header(skb
) + ihl
);
223 iph
= (void *)(icmph
+ 1);
226 new_addr
|= addr
& ~mask
;
228 /* XXX Fix up the inner checksums. */
230 iph
->daddr
= new_addr
;
232 iph
->saddr
= new_addr
;
234 inet_proto_csum_replace4(&icmph
->checksum
, skb
, addr
, new_addr
,
246 spin_lock(&p
->tcf_lock
);
247 p
->tcf_qstats
.drops
++;
248 spin_unlock(&p
->tcf_lock
);
252 static int tcf_nat_dump(struct sk_buff
*skb
, struct tc_action
*a
,
255 unsigned char *b
= skb_tail_pointer(skb
);
256 struct tcf_nat
*p
= a
->priv
;
257 struct tc_nat opt
= {
258 .old_addr
= p
->old_addr
,
259 .new_addr
= p
->new_addr
,
263 .index
= p
->tcf_index
,
264 .action
= p
->tcf_action
,
265 .refcnt
= p
->tcf_refcnt
- ref
,
266 .bindcnt
= p
->tcf_bindcnt
- bind
,
270 if (nla_put(skb
, TCA_NAT_PARMS
, sizeof(opt
), &opt
))
271 goto nla_put_failure
;
272 t
.install
= jiffies_to_clock_t(jiffies
- p
->tcf_tm
.install
);
273 t
.lastuse
= jiffies_to_clock_t(jiffies
- p
->tcf_tm
.lastuse
);
274 t
.expires
= jiffies_to_clock_t(p
->tcf_tm
.expires
);
275 if (nla_put(skb
, TCA_NAT_TM
, sizeof(t
), &t
))
276 goto nla_put_failure
;
285 static struct tc_action_ops act_nat_ops
= {
287 .hinfo
= &nat_hash_info
,
289 .owner
= THIS_MODULE
,
291 .dump
= tcf_nat_dump
,
292 .init
= tcf_nat_init
,
295 MODULE_DESCRIPTION("Stateless NAT actions");
296 MODULE_LICENSE("GPL");
298 static int __init
nat_init_module(void)
300 int err
= tcf_hashinfo_init(&nat_hash_info
, NAT_TAB_MASK
);
303 return tcf_register_action(&act_nat_ops
);
306 static void __exit
nat_cleanup_module(void)
308 tcf_unregister_action(&act_nat_ops
);
309 tcf_hashinfo_destroy(&nat_hash_info
);
312 module_init(nat_init_module
);
313 module_exit(nat_cleanup_module
);