Merge branch 'for-linus' of git://oss.sgi.com:8090/xfs/xfs-2.6
[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/scatterlist.h>
38 #include <asm/semaphore.h>
39 #include <linux/crypto.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         u8 mode = XFRM_MODE_TUNNEL;
194
195         t = xfrm_state_alloc();
196         if (!t)
197                 goto out;
198
199         t->id.proto = IPPROTO_IPV6;
200         t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
201         if (!t->id.spi)
202                 goto error;
203
204         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
205         memcpy(&t->sel, &x->sel, sizeof(t->sel));
206         t->props.family = AF_INET6;
207         if (x->props.mode == XFRM_MODE_BEET)
208                 mode = x->props.mode;
209         t->props.mode = mode;
210         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
211
212         if (xfrm_init_state(t))
213                 goto error;
214
215         atomic_set(&t->tunnel_users, 1);
216
217 out:
218         return t;
219
220 error:
221         t->km.state = XFRM_STATE_DEAD;
222         xfrm_state_put(t);
223         t = NULL;
224         goto out;
225 }
226
227 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
228 {
229         int err = 0;
230         struct xfrm_state *t = NULL;
231         __be32 spi;
232
233         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
234         if (spi)
235                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
236                                               spi, IPPROTO_IPV6, AF_INET6);
237         if (!t) {
238                 t = ipcomp6_tunnel_create(x);
239                 if (!t) {
240                         err = -EINVAL;
241                         goto out;
242                 }
243                 xfrm_state_insert(t);
244                 xfrm_state_hold(t);
245         }
246         x->tunnel = t;
247         atomic_inc(&t->tunnel_users);
248
249 out:
250         return err;
251 }
252
253 static void ipcomp6_free_scratches(void)
254 {
255         int i;
256         void **scratches;
257
258         if (--ipcomp6_scratch_users)
259                 return;
260
261         scratches = ipcomp6_scratches;
262         if (!scratches)
263                 return;
264
265         for_each_possible_cpu(i) {
266                 void *scratch = *per_cpu_ptr(scratches, i);
267
268                 vfree(scratch);
269         }
270
271         free_percpu(scratches);
272 }
273
274 static void **ipcomp6_alloc_scratches(void)
275 {
276         int i;
277         void **scratches;
278
279         if (ipcomp6_scratch_users++)
280                 return ipcomp6_scratches;
281
282         scratches = alloc_percpu(void *);
283         if (!scratches)
284                 return NULL;
285
286         ipcomp6_scratches = scratches;
287
288         for_each_possible_cpu(i) {
289                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
290                 if (!scratch)
291                         return NULL;
292                 *per_cpu_ptr(scratches, i) = scratch;
293         }
294
295         return scratches;
296 }
297
298 static void ipcomp6_free_tfms(struct crypto_comp **tfms)
299 {
300         struct ipcomp6_tfms *pos;
301         int cpu;
302
303         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
304                 if (pos->tfms == tfms)
305                         break;
306         }
307
308         BUG_TRAP(pos);
309
310         if (--pos->users)
311                 return;
312
313         list_del(&pos->list);
314         kfree(pos);
315
316         if (!tfms)
317                 return;
318
319         for_each_possible_cpu(cpu) {
320                 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
321                 crypto_free_comp(tfm);
322         }
323         free_percpu(tfms);
324 }
325
326 static struct crypto_comp **ipcomp6_alloc_tfms(const char *alg_name)
327 {
328         struct ipcomp6_tfms *pos;
329         struct crypto_comp **tfms;
330         int cpu;
331
332         /* This can be any valid CPU ID so we don't need locking. */
333         cpu = raw_smp_processor_id();
334
335         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
336                 struct crypto_comp *tfm;
337
338                 tfms = pos->tfms;
339                 tfm = *per_cpu_ptr(tfms, cpu);
340
341                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
342                         pos->users++;
343                         return tfms;
344                 }
345         }
346
347         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
348         if (!pos)
349                 return NULL;
350
351         pos->users = 1;
352         INIT_LIST_HEAD(&pos->list);
353         list_add(&pos->list, &ipcomp6_tfms_list);
354
355         pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
356         if (!tfms)
357                 goto error;
358
359         for_each_possible_cpu(cpu) {
360                 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
361                                                             CRYPTO_ALG_ASYNC);
362                 if (!tfm)
363                         goto error;
364                 *per_cpu_ptr(tfms, cpu) = tfm;
365         }
366
367         return tfms;
368
369 error:
370         ipcomp6_free_tfms(tfms);
371         return NULL;
372 }
373
374 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
375 {
376         if (ipcd->tfms)
377                 ipcomp6_free_tfms(ipcd->tfms);
378         ipcomp6_free_scratches();
379 }
380
381 static void ipcomp6_destroy(struct xfrm_state *x)
382 {
383         struct ipcomp_data *ipcd = x->data;
384         if (!ipcd)
385                 return;
386         xfrm_state_delete_tunnel(x);
387         mutex_lock(&ipcomp6_resource_mutex);
388         ipcomp6_free_data(ipcd);
389         mutex_unlock(&ipcomp6_resource_mutex);
390         kfree(ipcd);
391
392         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
393 }
394
395 static int ipcomp6_init_state(struct xfrm_state *x)
396 {
397         int err;
398         struct ipcomp_data *ipcd;
399         struct xfrm_algo_desc *calg_desc;
400
401         err = -EINVAL;
402         if (!x->calg)
403                 goto out;
404
405         if (x->encap)
406                 goto out;
407
408         err = -ENOMEM;
409         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
410         if (!ipcd)
411                 goto out;
412
413         x->props.header_len = 0;
414         if (x->props.mode == XFRM_MODE_TUNNEL)
415                 x->props.header_len += sizeof(struct ipv6hdr);
416
417         mutex_lock(&ipcomp6_resource_mutex);
418         if (!ipcomp6_alloc_scratches())
419                 goto error;
420
421         ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
422         if (!ipcd->tfms)
423                 goto error;
424         mutex_unlock(&ipcomp6_resource_mutex);
425
426         if (x->props.mode == XFRM_MODE_TUNNEL) {
427                 err = ipcomp6_tunnel_attach(x);
428                 if (err)
429                         goto error_tunnel;
430         }
431
432         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
433         BUG_ON(!calg_desc);
434         ipcd->threshold = calg_desc->uinfo.comp.threshold;
435         x->data = ipcd;
436         err = 0;
437 out:
438         return err;
439 error_tunnel:
440         mutex_lock(&ipcomp6_resource_mutex);
441 error:
442         ipcomp6_free_data(ipcd);
443         mutex_unlock(&ipcomp6_resource_mutex);
444         kfree(ipcd);
445
446         goto out;
447 }
448
449 static struct xfrm_type ipcomp6_type =
450 {
451         .description    = "IPCOMP6",
452         .owner          = THIS_MODULE,
453         .proto          = IPPROTO_COMP,
454         .init_state     = ipcomp6_init_state,
455         .destructor     = ipcomp6_destroy,
456         .input          = ipcomp6_input,
457         .output         = ipcomp6_output,
458         .hdr_offset     = xfrm6_find_1stfragopt,
459 };
460
461 static struct inet6_protocol ipcomp6_protocol =
462 {
463         .handler        = xfrm6_rcv,
464         .err_handler    = ipcomp6_err,
465         .flags          = INET6_PROTO_NOPOLICY,
466 };
467
468 static int __init ipcomp6_init(void)
469 {
470         if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
471                 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
472                 return -EAGAIN;
473         }
474         if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
475                 printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
476                 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
477                 return -EAGAIN;
478         }
479         return 0;
480 }
481
482 static void __exit ipcomp6_fini(void)
483 {
484         if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
485                 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
486         if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
487                 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
488 }
489
490 module_init(ipcomp6_init);
491 module_exit(ipcomp6_fini);
492 MODULE_LICENSE("GPL");
493 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
494 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
495
496 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);