netfilter: get rid of atomic ops in fast path
[linux-2.6.git] / net / ipv6 / xfrm6_tunnel.c
1 /*
2  * Copyright (C)2003,2004 USAGI/WIDE Project
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published by
6  * the Free Software Foundation; either version 2 of the License, or
7  * (at your option) any later version.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
17  *
18  * Authors      Mitsuru KANDA  <mk@linux-ipv6.org>
19  *              YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
20  *
21  * Based on net/ipv4/xfrm4_tunnel.c
22  *
23  */
24 #include <linux/module.h>
25 #include <linux/xfrm.h>
26 #include <linux/slab.h>
27 #include <linux/rculist.h>
28 #include <net/ip.h>
29 #include <net/xfrm.h>
30 #include <net/ipv6.h>
31 #include <linux/ipv6.h>
32 #include <linux/icmpv6.h>
33 #include <linux/mutex.h>
34 #include <net/netns/generic.h>
35
36 #define XFRM6_TUNNEL_SPI_BYADDR_HSIZE 256
37 #define XFRM6_TUNNEL_SPI_BYSPI_HSIZE 256
38
39 #define XFRM6_TUNNEL_SPI_MIN    1
40 #define XFRM6_TUNNEL_SPI_MAX    0xffffffff
41
42 struct xfrm6_tunnel_net {
43         struct hlist_head spi_byaddr[XFRM6_TUNNEL_SPI_BYADDR_HSIZE];
44         struct hlist_head spi_byspi[XFRM6_TUNNEL_SPI_BYSPI_HSIZE];
45         u32 spi;
46 };
47
48 static int xfrm6_tunnel_net_id __read_mostly;
49 static inline struct xfrm6_tunnel_net *xfrm6_tunnel_pernet(struct net *net)
50 {
51         return net_generic(net, xfrm6_tunnel_net_id);
52 }
53
54 /*
55  * xfrm_tunnel_spi things are for allocating unique id ("spi")
56  * per xfrm_address_t.
57  */
58 struct xfrm6_tunnel_spi {
59         struct hlist_node       list_byaddr;
60         struct hlist_node       list_byspi;
61         xfrm_address_t          addr;
62         u32                     spi;
63         atomic_t                refcnt;
64         struct rcu_head         rcu_head;
65 };
66
67 static DEFINE_SPINLOCK(xfrm6_tunnel_spi_lock);
68
69 static struct kmem_cache *xfrm6_tunnel_spi_kmem __read_mostly;
70
71 static inline unsigned xfrm6_tunnel_spi_hash_byaddr(xfrm_address_t *addr)
72 {
73         unsigned h;
74
75         h = (__force u32)(addr->a6[0] ^ addr->a6[1] ^ addr->a6[2] ^ addr->a6[3]);
76         h ^= h >> 16;
77         h ^= h >> 8;
78         h &= XFRM6_TUNNEL_SPI_BYADDR_HSIZE - 1;
79
80         return h;
81 }
82
83 static inline unsigned xfrm6_tunnel_spi_hash_byspi(u32 spi)
84 {
85         return spi % XFRM6_TUNNEL_SPI_BYSPI_HSIZE;
86 }
87
88 static struct xfrm6_tunnel_spi *__xfrm6_tunnel_spi_lookup(struct net *net, xfrm_address_t *saddr)
89 {
90         struct xfrm6_tunnel_net *xfrm6_tn = xfrm6_tunnel_pernet(net);
91         struct xfrm6_tunnel_spi *x6spi;
92         struct hlist_node *pos;
93
94         hlist_for_each_entry_rcu(x6spi, pos,
95                              &xfrm6_tn->spi_byaddr[xfrm6_tunnel_spi_hash_byaddr(saddr)],
96                              list_byaddr) {
97                 if (memcmp(&x6spi->addr, saddr, sizeof(x6spi->addr)) == 0)
98                         return x6spi;
99         }
100
101         return NULL;
102 }
103
104 __be32 xfrm6_tunnel_spi_lookup(struct net *net, xfrm_address_t *saddr)
105 {
106         struct xfrm6_tunnel_spi *x6spi;
107         u32 spi;
108
109         rcu_read_lock_bh();
110         x6spi = __xfrm6_tunnel_spi_lookup(net, saddr);
111         spi = x6spi ? x6spi->spi : 0;
112         rcu_read_unlock_bh();
113         return htonl(spi);
114 }
115
116 EXPORT_SYMBOL(xfrm6_tunnel_spi_lookup);
117
118 static int __xfrm6_tunnel_spi_check(struct net *net, u32 spi)
119 {
120         struct xfrm6_tunnel_net *xfrm6_tn = xfrm6_tunnel_pernet(net);
121         struct xfrm6_tunnel_spi *x6spi;
122         int index = xfrm6_tunnel_spi_hash_byspi(spi);
123         struct hlist_node *pos;
124
125         hlist_for_each_entry(x6spi, pos,
126                              &xfrm6_tn->spi_byspi[index],
127                              list_byspi) {
128                 if (x6spi->spi == spi)
129                         return -1;
130         }
131         return index;
132 }
133
134 static u32 __xfrm6_tunnel_alloc_spi(struct net *net, xfrm_address_t *saddr)
135 {
136         struct xfrm6_tunnel_net *xfrm6_tn = xfrm6_tunnel_pernet(net);
137         u32 spi;
138         struct xfrm6_tunnel_spi *x6spi;
139         int index;
140
141         if (xfrm6_tn->spi < XFRM6_TUNNEL_SPI_MIN ||
142             xfrm6_tn->spi >= XFRM6_TUNNEL_SPI_MAX)
143                 xfrm6_tn->spi = XFRM6_TUNNEL_SPI_MIN;
144         else
145                 xfrm6_tn->spi++;
146
147         for (spi = xfrm6_tn->spi; spi <= XFRM6_TUNNEL_SPI_MAX; spi++) {
148                 index = __xfrm6_tunnel_spi_check(net, spi);
149                 if (index >= 0)
150                         goto alloc_spi;
151         }
152         for (spi = XFRM6_TUNNEL_SPI_MIN; spi < xfrm6_tn->spi; spi++) {
153                 index = __xfrm6_tunnel_spi_check(net, spi);
154                 if (index >= 0)
155                         goto alloc_spi;
156         }
157         spi = 0;
158         goto out;
159 alloc_spi:
160         xfrm6_tn->spi = spi;
161         x6spi = kmem_cache_alloc(xfrm6_tunnel_spi_kmem, GFP_ATOMIC);
162         if (!x6spi)
163                 goto out;
164
165         memcpy(&x6spi->addr, saddr, sizeof(x6spi->addr));
166         x6spi->spi = spi;
167         atomic_set(&x6spi->refcnt, 1);
168
169         hlist_add_head_rcu(&x6spi->list_byspi, &xfrm6_tn->spi_byspi[index]);
170
171         index = xfrm6_tunnel_spi_hash_byaddr(saddr);
172         hlist_add_head_rcu(&x6spi->list_byaddr, &xfrm6_tn->spi_byaddr[index]);
173 out:
174         return spi;
175 }
176
177 __be32 xfrm6_tunnel_alloc_spi(struct net *net, xfrm_address_t *saddr)
178 {
179         struct xfrm6_tunnel_spi *x6spi;
180         u32 spi;
181
182         spin_lock_bh(&xfrm6_tunnel_spi_lock);
183         x6spi = __xfrm6_tunnel_spi_lookup(net, saddr);
184         if (x6spi) {
185                 atomic_inc(&x6spi->refcnt);
186                 spi = x6spi->spi;
187         } else
188                 spi = __xfrm6_tunnel_alloc_spi(net, saddr);
189         spin_unlock_bh(&xfrm6_tunnel_spi_lock);
190
191         return htonl(spi);
192 }
193
194 EXPORT_SYMBOL(xfrm6_tunnel_alloc_spi);
195
196 static void x6spi_destroy_rcu(struct rcu_head *head)
197 {
198         kmem_cache_free(xfrm6_tunnel_spi_kmem,
199                         container_of(head, struct xfrm6_tunnel_spi, rcu_head));
200 }
201
202 static void xfrm6_tunnel_free_spi(struct net *net, xfrm_address_t *saddr)
203 {
204         struct xfrm6_tunnel_net *xfrm6_tn = xfrm6_tunnel_pernet(net);
205         struct xfrm6_tunnel_spi *x6spi;
206         struct hlist_node *pos, *n;
207
208         spin_lock_bh(&xfrm6_tunnel_spi_lock);
209
210         hlist_for_each_entry_safe(x6spi, pos, n,
211                                   &xfrm6_tn->spi_byaddr[xfrm6_tunnel_spi_hash_byaddr(saddr)],
212                                   list_byaddr)
213         {
214                 if (memcmp(&x6spi->addr, saddr, sizeof(x6spi->addr)) == 0) {
215                         if (atomic_dec_and_test(&x6spi->refcnt)) {
216                                 hlist_del_rcu(&x6spi->list_byaddr);
217                                 hlist_del_rcu(&x6spi->list_byspi);
218                                 call_rcu(&x6spi->rcu_head, x6spi_destroy_rcu);
219                                 break;
220                         }
221                 }
222         }
223         spin_unlock_bh(&xfrm6_tunnel_spi_lock);
224 }
225
226 static int xfrm6_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
227 {
228         skb_push(skb, -skb_network_offset(skb));
229         return 0;
230 }
231
232 static int xfrm6_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
233 {
234         return skb_network_header(skb)[IP6CB(skb)->nhoff];
235 }
236
237 static int xfrm6_tunnel_rcv(struct sk_buff *skb)
238 {
239         struct net *net = dev_net(skb->dev);
240         struct ipv6hdr *iph = ipv6_hdr(skb);
241         __be32 spi;
242
243         spi = xfrm6_tunnel_spi_lookup(net, (xfrm_address_t *)&iph->saddr);
244         return xfrm6_rcv_spi(skb, IPPROTO_IPV6, spi) > 0 ? : 0;
245 }
246
247 static int xfrm6_tunnel_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
248                             u8 type, u8 code, int offset, __be32 info)
249 {
250         /* xfrm6_tunnel native err handling */
251         switch (type) {
252         case ICMPV6_DEST_UNREACH:
253                 switch (code) {
254                 case ICMPV6_NOROUTE:
255                 case ICMPV6_ADM_PROHIBITED:
256                 case ICMPV6_NOT_NEIGHBOUR:
257                 case ICMPV6_ADDR_UNREACH:
258                 case ICMPV6_PORT_UNREACH:
259                 default:
260                         break;
261                 }
262                 break;
263         case ICMPV6_PKT_TOOBIG:
264                 break;
265         case ICMPV6_TIME_EXCEED:
266                 switch (code) {
267                 case ICMPV6_EXC_HOPLIMIT:
268                         break;
269                 case ICMPV6_EXC_FRAGTIME:
270                 default:
271                         break;
272                 }
273                 break;
274         case ICMPV6_PARAMPROB:
275                 switch (code) {
276                 case ICMPV6_HDR_FIELD: break;
277                 case ICMPV6_UNK_NEXTHDR: break;
278                 case ICMPV6_UNK_OPTION: break;
279                 }
280                 break;
281         default:
282                 break;
283         }
284
285         return 0;
286 }
287
288 static int xfrm6_tunnel_init_state(struct xfrm_state *x)
289 {
290         if (x->props.mode != XFRM_MODE_TUNNEL)
291                 return -EINVAL;
292
293         if (x->encap)
294                 return -EINVAL;
295
296         x->props.header_len = sizeof(struct ipv6hdr);
297
298         return 0;
299 }
300
301 static void xfrm6_tunnel_destroy(struct xfrm_state *x)
302 {
303         struct net *net = xs_net(x);
304
305         xfrm6_tunnel_free_spi(net, (xfrm_address_t *)&x->props.saddr);
306 }
307
308 static const struct xfrm_type xfrm6_tunnel_type = {
309         .description    = "IP6IP6",
310         .owner          = THIS_MODULE,
311         .proto          = IPPROTO_IPV6,
312         .init_state     = xfrm6_tunnel_init_state,
313         .destructor     = xfrm6_tunnel_destroy,
314         .input          = xfrm6_tunnel_input,
315         .output         = xfrm6_tunnel_output,
316 };
317
318 static struct xfrm6_tunnel xfrm6_tunnel_handler __read_mostly = {
319         .handler        = xfrm6_tunnel_rcv,
320         .err_handler    = xfrm6_tunnel_err,
321         .priority       = 2,
322 };
323
324 static struct xfrm6_tunnel xfrm46_tunnel_handler __read_mostly = {
325         .handler        = xfrm6_tunnel_rcv,
326         .err_handler    = xfrm6_tunnel_err,
327         .priority       = 2,
328 };
329
330 static int __net_init xfrm6_tunnel_net_init(struct net *net)
331 {
332         struct xfrm6_tunnel_net *xfrm6_tn = xfrm6_tunnel_pernet(net);
333         unsigned int i;
334
335         for (i = 0; i < XFRM6_TUNNEL_SPI_BYADDR_HSIZE; i++)
336                 INIT_HLIST_HEAD(&xfrm6_tn->spi_byaddr[i]);
337         for (i = 0; i < XFRM6_TUNNEL_SPI_BYSPI_HSIZE; i++)
338                 INIT_HLIST_HEAD(&xfrm6_tn->spi_byspi[i]);
339         xfrm6_tn->spi = 0;
340
341         return 0;
342 }
343
344 static void __net_exit xfrm6_tunnel_net_exit(struct net *net)
345 {
346 }
347
348 static struct pernet_operations xfrm6_tunnel_net_ops = {
349         .init   = xfrm6_tunnel_net_init,
350         .exit   = xfrm6_tunnel_net_exit,
351         .id     = &xfrm6_tunnel_net_id,
352         .size   = sizeof(struct xfrm6_tunnel_net),
353 };
354
355 static int __init xfrm6_tunnel_init(void)
356 {
357         int rv;
358
359         xfrm6_tunnel_spi_kmem = kmem_cache_create("xfrm6_tunnel_spi",
360                                                   sizeof(struct xfrm6_tunnel_spi),
361                                                   0, SLAB_HWCACHE_ALIGN,
362                                                   NULL);
363         if (!xfrm6_tunnel_spi_kmem)
364                 return -ENOMEM;
365         rv = register_pernet_subsys(&xfrm6_tunnel_net_ops);
366         if (rv < 0)
367                 goto out_pernet;
368         rv = xfrm_register_type(&xfrm6_tunnel_type, AF_INET6);
369         if (rv < 0)
370                 goto out_type;
371         rv = xfrm6_tunnel_register(&xfrm6_tunnel_handler, AF_INET6);
372         if (rv < 0)
373                 goto out_xfrm6;
374         rv = xfrm6_tunnel_register(&xfrm46_tunnel_handler, AF_INET);
375         if (rv < 0)
376                 goto out_xfrm46;
377         return 0;
378
379 out_xfrm46:
380         xfrm6_tunnel_deregister(&xfrm6_tunnel_handler, AF_INET6);
381 out_xfrm6:
382         xfrm_unregister_type(&xfrm6_tunnel_type, AF_INET6);
383 out_type:
384         unregister_pernet_subsys(&xfrm6_tunnel_net_ops);
385 out_pernet:
386         kmem_cache_destroy(xfrm6_tunnel_spi_kmem);
387         return rv;
388 }
389
390 static void __exit xfrm6_tunnel_fini(void)
391 {
392         xfrm6_tunnel_deregister(&xfrm46_tunnel_handler, AF_INET);
393         xfrm6_tunnel_deregister(&xfrm6_tunnel_handler, AF_INET6);
394         xfrm_unregister_type(&xfrm6_tunnel_type, AF_INET6);
395         unregister_pernet_subsys(&xfrm6_tunnel_net_ops);
396         kmem_cache_destroy(xfrm6_tunnel_spi_kmem);
397 }
398
399 module_init(xfrm6_tunnel_init);
400 module_exit(xfrm6_tunnel_fini);
401 MODULE_LICENSE("GPL");
402 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_IPV6);