Merge HEAD from ../linux-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/config.h>
34 #include <linux/module.h>
35 #include <net/ip.h>
36 #include <net/xfrm.h>
37 #include <net/ipcomp.h>
38 #include <asm/scatterlist.h>
39 #include <asm/semaphore.h>
40 #include <linux/crypto.h>
41 #include <linux/pfkeyv2.h>
42 #include <linux/random.h>
43 #include <linux/percpu.h>
44 #include <linux/smp.h>
45 #include <linux/list.h>
46 #include <linux/vmalloc.h>
47 #include <linux/rtnetlink.h>
48 #include <net/icmp.h>
49 #include <net/ipv6.h>
50 #include <net/protocol.h>
51 #include <linux/ipv6.h>
52 #include <linux/icmpv6.h>
53 #include <linux/mutex.h>
54
55 struct ipcomp6_tfms {
56         struct list_head list;
57         struct crypto_tfm **tfms;
58         int users;
59 };
60
61 static DEFINE_MUTEX(ipcomp6_resource_mutex);
62 static void **ipcomp6_scratches;
63 static int ipcomp6_scratch_users;
64 static LIST_HEAD(ipcomp6_tfms_list);
65
66 static int ipcomp6_input(struct xfrm_state *x, struct sk_buff *skb)
67 {
68         int err = -ENOMEM;
69         struct ipv6hdr *iph;
70         struct ipv6_comp_hdr *ipch;
71         int plen, dlen;
72         struct ipcomp_data *ipcd = x->data;
73         u8 *start, *scratch;
74         struct crypto_tfm *tfm;
75         int cpu;
76
77         if (skb_linearize_cow(skb))
78                 goto out;
79
80         skb->ip_summed = CHECKSUM_NONE;
81
82         /* Remove ipcomp header and decompress original payload */
83         iph = skb->nh.ipv6h;
84         ipch = (void *)skb->data;
85         skb->h.raw = skb->nh.raw + sizeof(*ipch);
86         __skb_pull(skb, sizeof(*ipch));
87
88         /* decompression */
89         plen = skb->len;
90         dlen = IPCOMP_SCRATCH_SIZE;
91         start = skb->data;
92
93         cpu = get_cpu();
94         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
95         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
96
97         err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
98         if (err) {
99                 err = -EINVAL;
100                 goto out_put_cpu;
101         }
102
103         if (dlen < (plen + sizeof(struct ipv6_comp_hdr))) {
104                 err = -EINVAL;
105                 goto out_put_cpu;
106         }
107
108         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
109         if (err) {
110                 goto out_put_cpu;
111         }
112
113         skb_put(skb, dlen - plen);
114         memcpy(skb->data, scratch, dlen);
115         err = ipch->nexthdr;
116
117 out_put_cpu:
118         put_cpu();
119 out:
120         return err;
121 }
122
123 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb)
124 {
125         int err;
126         struct ipv6hdr *top_iph;
127         int hdr_len;
128         struct ipv6_comp_hdr *ipch;
129         struct ipcomp_data *ipcd = x->data;
130         int plen, dlen;
131         u8 *start, *scratch;
132         struct crypto_tfm *tfm;
133         int cpu;
134
135         hdr_len = skb->h.raw - skb->data;
136
137         /* check whether datagram len is larger than threshold */
138         if ((skb->len - hdr_len) < ipcd->threshold) {
139                 goto out_ok;
140         }
141
142         if (skb_linearize_cow(skb))
143                 goto out_ok;
144
145         /* compression */
146         plen = skb->len - hdr_len;
147         dlen = IPCOMP_SCRATCH_SIZE;
148         start = skb->h.raw;
149
150         cpu = get_cpu();
151         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
152         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
153
154         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
155         if (err || (dlen + sizeof(struct ipv6_comp_hdr)) >= plen) {
156                 put_cpu();
157                 goto out_ok;
158         }
159         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
160         put_cpu();
161         pskb_trim(skb, hdr_len + dlen + sizeof(struct ip_comp_hdr));
162
163         /* insert ipcomp header and replace datagram */
164         top_iph = (struct ipv6hdr *)skb->data;
165
166         top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
167
168         ipch = (struct ipv6_comp_hdr *)start;
169         ipch->nexthdr = *skb->nh.raw;
170         ipch->flags = 0;
171         ipch->cpi = htons((u16 )ntohl(x->id.spi));
172         *skb->nh.raw = IPPROTO_COMP;
173
174 out_ok:
175         return 0;
176 }
177
178 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
179                                 int type, int code, int offset, __u32 info)
180 {
181         u32 spi;
182         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
183         struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset);
184         struct xfrm_state *x;
185
186         if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
187                 return;
188
189         spi = htonl(ntohs(ipcomph->cpi));
190         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
191         if (!x)
192                 return;
193
194         printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n",
195                         spi, NIP6(iph->daddr));
196         xfrm_state_put(x);
197 }
198
199 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
200 {
201         struct xfrm_state *t = NULL;
202
203         t = xfrm_state_alloc();
204         if (!t)
205                 goto out;
206
207         t->id.proto = IPPROTO_IPV6;
208         t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
209         if (!t->id.spi)
210                 goto error;
211
212         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
213         memcpy(&t->sel, &x->sel, sizeof(t->sel));
214         t->props.family = AF_INET6;
215         t->props.mode = 1;
216         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
217
218         if (xfrm_init_state(t))
219                 goto error;
220
221         atomic_set(&t->tunnel_users, 1);
222
223 out:
224         return t;
225
226 error:
227         t->km.state = XFRM_STATE_DEAD;
228         xfrm_state_put(t);
229         t = NULL;
230         goto out;
231 }
232
233 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
234 {
235         int err = 0;
236         struct xfrm_state *t = NULL;
237         u32 spi;
238
239         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
240         if (spi)
241                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
242                                               spi, IPPROTO_IPV6, AF_INET6);
243         if (!t) {
244                 t = ipcomp6_tunnel_create(x);
245                 if (!t) {
246                         err = -EINVAL;
247                         goto out;
248                 }
249                 xfrm_state_insert(t);
250                 xfrm_state_hold(t);
251         }
252         x->tunnel = t;
253         atomic_inc(&t->tunnel_users);
254
255 out:
256         return err;
257 }
258
259 static void ipcomp6_free_scratches(void)
260 {
261         int i;
262         void **scratches;
263
264         if (--ipcomp6_scratch_users)
265                 return;
266
267         scratches = ipcomp6_scratches;
268         if (!scratches)
269                 return;
270
271         for_each_possible_cpu(i) {
272                 void *scratch = *per_cpu_ptr(scratches, i);
273
274                 vfree(scratch);
275         }
276
277         free_percpu(scratches);
278 }
279
280 static void **ipcomp6_alloc_scratches(void)
281 {
282         int i;
283         void **scratches;
284
285         if (ipcomp6_scratch_users++)
286                 return ipcomp6_scratches;
287
288         scratches = alloc_percpu(void *);
289         if (!scratches)
290                 return NULL;
291
292         ipcomp6_scratches = scratches;
293
294         for_each_possible_cpu(i) {
295                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
296                 if (!scratch)
297                         return NULL;
298                 *per_cpu_ptr(scratches, i) = scratch;
299         }
300
301         return scratches;
302 }
303
304 static void ipcomp6_free_tfms(struct crypto_tfm **tfms)
305 {
306         struct ipcomp6_tfms *pos;
307         int cpu;
308
309         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
310                 if (pos->tfms == tfms)
311                         break;
312         }
313
314         BUG_TRAP(pos);
315
316         if (--pos->users)
317                 return;
318
319         list_del(&pos->list);
320         kfree(pos);
321
322         if (!tfms)
323                 return;
324
325         for_each_possible_cpu(cpu) {
326                 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu);
327                 crypto_free_tfm(tfm);
328         }
329         free_percpu(tfms);
330 }
331
332 static struct crypto_tfm **ipcomp6_alloc_tfms(const char *alg_name)
333 {
334         struct ipcomp6_tfms *pos;
335         struct crypto_tfm **tfms;
336         int cpu;
337
338         /* This can be any valid CPU ID so we don't need locking. */
339         cpu = raw_smp_processor_id();
340
341         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
342                 struct crypto_tfm *tfm;
343
344                 tfms = pos->tfms;
345                 tfm = *per_cpu_ptr(tfms, cpu);
346
347                 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) {
348                         pos->users++;
349                         return tfms;
350                 }
351         }
352
353         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
354         if (!pos)
355                 return NULL;
356
357         pos->users = 1;
358         INIT_LIST_HEAD(&pos->list);
359         list_add(&pos->list, &ipcomp6_tfms_list);
360
361         pos->tfms = tfms = alloc_percpu(struct crypto_tfm *);
362         if (!tfms)
363                 goto error;
364
365         for_each_possible_cpu(cpu) {
366                 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0);
367                 if (!tfm)
368                         goto error;
369                 *per_cpu_ptr(tfms, cpu) = tfm;
370         }
371
372         return tfms;
373
374 error:
375         ipcomp6_free_tfms(tfms);
376         return NULL;
377 }
378
379 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
380 {
381         if (ipcd->tfms)
382                 ipcomp6_free_tfms(ipcd->tfms);
383         ipcomp6_free_scratches();
384 }
385
386 static void ipcomp6_destroy(struct xfrm_state *x)
387 {
388         struct ipcomp_data *ipcd = x->data;
389         if (!ipcd)
390                 return;
391         xfrm_state_delete_tunnel(x);
392         mutex_lock(&ipcomp6_resource_mutex);
393         ipcomp6_free_data(ipcd);
394         mutex_unlock(&ipcomp6_resource_mutex);
395         kfree(ipcd);
396
397         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
398 }
399
400 static int ipcomp6_init_state(struct xfrm_state *x)
401 {
402         int err;
403         struct ipcomp_data *ipcd;
404         struct xfrm_algo_desc *calg_desc;
405
406         err = -EINVAL;
407         if (!x->calg)
408                 goto out;
409
410         if (x->encap)
411                 goto out;
412
413         err = -ENOMEM;
414         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
415         if (!ipcd)
416                 goto out;
417
418         x->props.header_len = 0;
419         if (x->props.mode)
420                 x->props.header_len += sizeof(struct ipv6hdr);
421         
422         mutex_lock(&ipcomp6_resource_mutex);
423         if (!ipcomp6_alloc_scratches())
424                 goto error;
425
426         ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
427         if (!ipcd->tfms)
428                 goto error;
429         mutex_unlock(&ipcomp6_resource_mutex);
430
431         if (x->props.mode) {
432                 err = ipcomp6_tunnel_attach(x);
433                 if (err)
434                         goto error_tunnel;
435         }
436
437         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
438         BUG_ON(!calg_desc);
439         ipcd->threshold = calg_desc->uinfo.comp.threshold;
440         x->data = ipcd;
441         err = 0;
442 out:
443         return err;
444 error_tunnel:
445         mutex_lock(&ipcomp6_resource_mutex);
446 error:
447         ipcomp6_free_data(ipcd);
448         mutex_unlock(&ipcomp6_resource_mutex);
449         kfree(ipcd);
450
451         goto out;
452 }
453
454 static struct xfrm_type ipcomp6_type = 
455 {
456         .description    = "IPCOMP6",
457         .owner          = THIS_MODULE,
458         .proto          = IPPROTO_COMP,
459         .init_state     = ipcomp6_init_state,
460         .destructor     = ipcomp6_destroy,
461         .input          = ipcomp6_input,
462         .output         = ipcomp6_output,
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