Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris...
[linux-2.6] / net / ipv6 / ipcomp6.c
1 /*
2  * IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173
3  *
4  * Copyright (C)2003 USAGI/WIDE Project
5  *
6  * Author       Mitsuru KANDA  <mk@linux-ipv6.org>
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License as published by
10  * the Free Software Foundation; either version 2 of the License, or
11  * (at your option) any later version.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public License
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
21  */
22 /*
23  * [Memo]
24  *
25  * Outbound:
26  *  The compression of IP datagram MUST be done before AH/ESP processing,
27  *  fragmentation, and the addition of Hop-by-Hop/Routing header.
28  *
29  * Inbound:
30  *  The decompression of IP datagram MUST be done after the reassembly,
31  *  AH/ESP processing.
32  */
33 #include <linux/module.h>
34 #include <net/ip.h>
35 #include <net/xfrm.h>
36 #include <net/ipcomp.h>
37 #include <asm/semaphore.h>
38 #include <linux/crypto.h>
39 #include <linux/err.h>
40 #include <linux/pfkeyv2.h>
41 #include <linux/random.h>
42 #include <linux/percpu.h>
43 #include <linux/smp.h>
44 #include <linux/list.h>
45 #include <linux/vmalloc.h>
46 #include <linux/rtnetlink.h>
47 #include <net/icmp.h>
48 #include <net/ipv6.h>
49 #include <net/protocol.h>
50 #include <linux/ipv6.h>
51 #include <linux/icmpv6.h>
52 #include <linux/mutex.h>
53
54 struct ipcomp6_tfms {
55         struct list_head list;
56         struct crypto_comp **tfms;
57         int users;
58 };
59
60 static DEFINE_MUTEX(ipcomp6_resource_mutex);
61 static void **ipcomp6_scratches;
62 static int ipcomp6_scratch_users;
63 static LIST_HEAD(ipcomp6_tfms_list);
64
65 static int ipcomp6_input(struct xfrm_state *x, struct sk_buff *skb)
66 {
67         int err = -ENOMEM;
68         struct ip_comp_hdr *ipch;
69         int plen, dlen;
70         struct ipcomp_data *ipcd = x->data;
71         u8 *start, *scratch;
72         struct crypto_comp *tfm;
73         int cpu;
74
75         if (skb_linearize_cow(skb))
76                 goto out;
77
78         skb->ip_summed = CHECKSUM_NONE;
79
80         /* Remove ipcomp header and decompress original payload */
81         ipch = (void *)skb->data;
82         skb->transport_header = skb->network_header + sizeof(*ipch);
83         __skb_pull(skb, sizeof(*ipch));
84
85         /* decompression */
86         plen = skb->len;
87         dlen = IPCOMP_SCRATCH_SIZE;
88         start = skb->data;
89
90         cpu = get_cpu();
91         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
92         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
93
94         err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
95         if (err)
96                 goto out_put_cpu;
97
98         if (dlen < (plen + sizeof(*ipch))) {
99                 err = -EINVAL;
100                 goto out_put_cpu;
101         }
102
103         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
104         if (err) {
105                 goto out_put_cpu;
106         }
107
108         skb->truesize += dlen - plen;
109         __skb_put(skb, dlen - plen);
110         skb_copy_to_linear_data(skb, scratch, dlen);
111         err = ipch->nexthdr;
112
113 out_put_cpu:
114         put_cpu();
115 out:
116         return err;
117 }
118
119 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb)
120 {
121         int err;
122         struct ip_comp_hdr *ipch;
123         struct ipcomp_data *ipcd = x->data;
124         int plen, dlen;
125         u8 *start, *scratch;
126         struct crypto_comp *tfm;
127         int cpu;
128
129         /* check whether datagram len is larger than threshold */
130         if (skb->len < ipcd->threshold) {
131                 goto out_ok;
132         }
133
134         if (skb_linearize_cow(skb))
135                 goto out_ok;
136
137         /* compression */
138         plen = skb->len;
139         dlen = IPCOMP_SCRATCH_SIZE;
140         start = skb->data;
141
142         cpu = get_cpu();
143         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
144         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
145
146         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
147         if (err || (dlen + sizeof(*ipch)) >= plen) {
148                 put_cpu();
149                 goto out_ok;
150         }
151         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
152         put_cpu();
153         pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
154
155         /* insert ipcomp header and replace datagram */
156         ipch = ip_comp_hdr(skb);
157         ipch->nexthdr = *skb_mac_header(skb);
158         ipch->flags = 0;
159         ipch->cpi = htons((u16 )ntohl(x->id.spi));
160         *skb_mac_header(skb) = IPPROTO_COMP;
161
162 out_ok:
163         skb_push(skb, -skb_network_offset(skb));
164
165         return 0;
166 }
167
168 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
169                                 int type, int code, int offset, __be32 info)
170 {
171         __be32 spi;
172         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
173         struct ip_comp_hdr *ipcomph =
174                 (struct ip_comp_hdr *)(skb->data + offset);
175         struct xfrm_state *x;
176
177         if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
178                 return;
179
180         spi = htonl(ntohs(ipcomph->cpi));
181         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
182         if (!x)
183                 return;
184
185         printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n",
186                         spi, NIP6(iph->daddr));
187         xfrm_state_put(x);
188 }
189
190 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
191 {
192         struct xfrm_state *t = NULL;
193
194         t = xfrm_state_alloc();
195         if (!t)
196                 goto out;
197
198         t->id.proto = IPPROTO_IPV6;
199         t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
200         if (!t->id.spi)
201                 goto error;
202
203         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
204         memcpy(&t->sel, &x->sel, sizeof(t->sel));
205         t->props.family = AF_INET6;
206         t->props.mode = x->props.mode;
207         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
208
209         if (xfrm_init_state(t))
210                 goto error;
211
212         atomic_set(&t->tunnel_users, 1);
213
214 out:
215         return t;
216
217 error:
218         t->km.state = XFRM_STATE_DEAD;
219         xfrm_state_put(t);
220         t = NULL;
221         goto out;
222 }
223
224 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
225 {
226         int err = 0;
227         struct xfrm_state *t = NULL;
228         __be32 spi;
229
230         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
231         if (spi)
232                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
233                                               spi, IPPROTO_IPV6, AF_INET6);
234         if (!t) {
235                 t = ipcomp6_tunnel_create(x);
236                 if (!t) {
237                         err = -EINVAL;
238                         goto out;
239                 }
240                 xfrm_state_insert(t);
241                 xfrm_state_hold(t);
242         }
243         x->tunnel = t;
244         atomic_inc(&t->tunnel_users);
245
246 out:
247         return err;
248 }
249
250 static void ipcomp6_free_scratches(void)
251 {
252         int i;
253         void **scratches;
254
255         if (--ipcomp6_scratch_users)
256                 return;
257
258         scratches = ipcomp6_scratches;
259         if (!scratches)
260                 return;
261
262         for_each_possible_cpu(i) {
263                 void *scratch = *per_cpu_ptr(scratches, i);
264
265                 vfree(scratch);
266         }
267
268         free_percpu(scratches);
269 }
270
271 static void **ipcomp6_alloc_scratches(void)
272 {
273         int i;
274         void **scratches;
275
276         if (ipcomp6_scratch_users++)
277                 return ipcomp6_scratches;
278
279         scratches = alloc_percpu(void *);
280         if (!scratches)
281                 return NULL;
282
283         ipcomp6_scratches = scratches;
284
285         for_each_possible_cpu(i) {
286                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
287                 if (!scratch)
288                         return NULL;
289                 *per_cpu_ptr(scratches, i) = scratch;
290         }
291
292         return scratches;
293 }
294
295 static void ipcomp6_free_tfms(struct crypto_comp **tfms)
296 {
297         struct ipcomp6_tfms *pos;
298         int cpu;
299
300         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
301                 if (pos->tfms == tfms)
302                         break;
303         }
304
305         BUG_TRAP(pos);
306
307         if (--pos->users)
308                 return;
309
310         list_del(&pos->list);
311         kfree(pos);
312
313         if (!tfms)
314                 return;
315
316         for_each_possible_cpu(cpu) {
317                 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
318                 crypto_free_comp(tfm);
319         }
320         free_percpu(tfms);
321 }
322
323 static struct crypto_comp **ipcomp6_alloc_tfms(const char *alg_name)
324 {
325         struct ipcomp6_tfms *pos;
326         struct crypto_comp **tfms;
327         int cpu;
328
329         /* This can be any valid CPU ID so we don't need locking. */
330         cpu = raw_smp_processor_id();
331
332         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
333                 struct crypto_comp *tfm;
334
335                 tfms = pos->tfms;
336                 tfm = *per_cpu_ptr(tfms, cpu);
337
338                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
339                         pos->users++;
340                         return tfms;
341                 }
342         }
343
344         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
345         if (!pos)
346                 return NULL;
347
348         pos->users = 1;
349         INIT_LIST_HEAD(&pos->list);
350         list_add(&pos->list, &ipcomp6_tfms_list);
351
352         pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
353         if (!tfms)
354                 goto error;
355
356         for_each_possible_cpu(cpu) {
357                 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
358                                                             CRYPTO_ALG_ASYNC);
359                 if (IS_ERR(tfm))
360                         goto error;
361                 *per_cpu_ptr(tfms, cpu) = tfm;
362         }
363
364         return tfms;
365
366 error:
367         ipcomp6_free_tfms(tfms);
368         return NULL;
369 }
370
371 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
372 {
373         if (ipcd->tfms)
374                 ipcomp6_free_tfms(ipcd->tfms);
375         ipcomp6_free_scratches();
376 }
377
378 static void ipcomp6_destroy(struct xfrm_state *x)
379 {
380         struct ipcomp_data *ipcd = x->data;
381         if (!ipcd)
382                 return;
383         xfrm_state_delete_tunnel(x);
384         mutex_lock(&ipcomp6_resource_mutex);
385         ipcomp6_free_data(ipcd);
386         mutex_unlock(&ipcomp6_resource_mutex);
387         kfree(ipcd);
388
389         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
390 }
391
392 static int ipcomp6_init_state(struct xfrm_state *x)
393 {
394         int err;
395         struct ipcomp_data *ipcd;
396         struct xfrm_algo_desc *calg_desc;
397
398         err = -EINVAL;
399         if (!x->calg)
400                 goto out;
401
402         if (x->encap)
403                 goto out;
404
405         x->props.header_len = 0;
406         switch (x->props.mode) {
407         case XFRM_MODE_TRANSPORT:
408                 break;
409         case XFRM_MODE_TUNNEL:
410                 x->props.header_len += sizeof(struct ipv6hdr);
411                 break;
412         default:
413                 goto out;
414         }
415
416         err = -ENOMEM;
417         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
418         if (!ipcd)
419                 goto out;
420
421         mutex_lock(&ipcomp6_resource_mutex);
422         if (!ipcomp6_alloc_scratches())
423                 goto error;
424
425         ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
426         if (!ipcd->tfms)
427                 goto error;
428         mutex_unlock(&ipcomp6_resource_mutex);
429
430         if (x->props.mode == XFRM_MODE_TUNNEL) {
431                 err = ipcomp6_tunnel_attach(x);
432                 if (err)
433                         goto error_tunnel;
434         }
435
436         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
437         BUG_ON(!calg_desc);
438         ipcd->threshold = calg_desc->uinfo.comp.threshold;
439         x->data = ipcd;
440         err = 0;
441 out:
442         return err;
443 error_tunnel:
444         mutex_lock(&ipcomp6_resource_mutex);
445 error:
446         ipcomp6_free_data(ipcd);
447         mutex_unlock(&ipcomp6_resource_mutex);
448         kfree(ipcd);
449
450         goto out;
451 }
452
453 static struct xfrm_type ipcomp6_type =
454 {
455         .description    = "IPCOMP6",
456         .owner          = THIS_MODULE,
457         .proto          = IPPROTO_COMP,
458         .init_state     = ipcomp6_init_state,
459         .destructor     = ipcomp6_destroy,
460         .input          = ipcomp6_input,
461         .output         = ipcomp6_output,
462         .hdr_offset     = xfrm6_find_1stfragopt,
463 };
464
465 static struct inet6_protocol ipcomp6_protocol =
466 {
467         .handler        = xfrm6_rcv,
468         .err_handler    = ipcomp6_err,
469         .flags          = INET6_PROTO_NOPOLICY,
470 };
471
472 static int __init ipcomp6_init(void)
473 {
474         if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
475                 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
476                 return -EAGAIN;
477         }
478         if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
479                 printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
480                 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
481                 return -EAGAIN;
482         }
483         return 0;
484 }
485
486 static void __exit ipcomp6_fini(void)
487 {
488         if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
489                 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
490         if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
491                 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
492 }
493
494 module_init(ipcomp6_init);
495 module_exit(ipcomp6_fini);
496 MODULE_LICENSE("GPL");
497 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
498 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
499
500 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);