[XFRM]: Add XFRM_MODE_xxx for future use.
[linux-2.6.git] / 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 ipv6hdr *iph;
69         struct ipv6_comp_hdr *ipch;
70         int plen, dlen;
71         struct ipcomp_data *ipcd = x->data;
72         u8 *start, *scratch;
73         struct crypto_comp *tfm;
74         int cpu;
75
76         if (skb_linearize_cow(skb))
77                 goto out;
78
79         skb->ip_summed = CHECKSUM_NONE;
80
81         /* Remove ipcomp header and decompress original payload */
82         iph = skb->nh.ipv6h;
83         ipch = (void *)skb->data;
84         skb->h.raw = skb->nh.raw + sizeof(*ipch);
85         __skb_pull(skb, sizeof(*ipch));
86
87         /* decompression */
88         plen = skb->len;
89         dlen = IPCOMP_SCRATCH_SIZE;
90         start = skb->data;
91
92         cpu = get_cpu();
93         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
94         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
95
96         err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
97         if (err) {
98                 err = -EINVAL;
99                 goto out_put_cpu;
100         }
101
102         if (dlen < (plen + sizeof(struct ipv6_comp_hdr))) {
103                 err = -EINVAL;
104                 goto out_put_cpu;
105         }
106
107         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
108         if (err) {
109                 goto out_put_cpu;
110         }
111
112         skb->truesize += dlen - plen;
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_comp *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 = XFRM_MODE_TUNNEL;
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_comp **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_comp *tfm = *per_cpu_ptr(tfms, cpu);
327                 crypto_free_comp(tfm);
328         }
329         free_percpu(tfms);
330 }
331
332 static struct crypto_comp **ipcomp6_alloc_tfms(const char *alg_name)
333 {
334         struct ipcomp6_tfms *pos;
335         struct crypto_comp **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_comp *tfm;
343
344                 tfms = pos->tfms;
345                 tfm = *per_cpu_ptr(tfms, cpu);
346
347                 if (!strcmp(crypto_comp_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_comp *);
362         if (!tfms)
363                 goto error;
364
365         for_each_possible_cpu(cpu) {
366                 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
367                                                             CRYPTO_ALG_ASYNC);
368                 if (!tfm)
369                         goto error;
370                 *per_cpu_ptr(tfms, cpu) = tfm;
371         }
372
373         return tfms;
374
375 error:
376         ipcomp6_free_tfms(tfms);
377         return NULL;
378 }
379
380 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
381 {
382         if (ipcd->tfms)
383                 ipcomp6_free_tfms(ipcd->tfms);
384         ipcomp6_free_scratches();
385 }
386
387 static void ipcomp6_destroy(struct xfrm_state *x)
388 {
389         struct ipcomp_data *ipcd = x->data;
390         if (!ipcd)
391                 return;
392         xfrm_state_delete_tunnel(x);
393         mutex_lock(&ipcomp6_resource_mutex);
394         ipcomp6_free_data(ipcd);
395         mutex_unlock(&ipcomp6_resource_mutex);
396         kfree(ipcd);
397
398         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
399 }
400
401 static int ipcomp6_init_state(struct xfrm_state *x)
402 {
403         int err;
404         struct ipcomp_data *ipcd;
405         struct xfrm_algo_desc *calg_desc;
406
407         err = -EINVAL;
408         if (!x->calg)
409                 goto out;
410
411         if (x->encap)
412                 goto out;
413
414         err = -ENOMEM;
415         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
416         if (!ipcd)
417                 goto out;
418
419         x->props.header_len = 0;
420         if (x->props.mode == XFRM_MODE_TUNNEL)
421                 x->props.header_len += sizeof(struct ipv6hdr);
422         
423         mutex_lock(&ipcomp6_resource_mutex);
424         if (!ipcomp6_alloc_scratches())
425                 goto error;
426
427         ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
428         if (!ipcd->tfms)
429                 goto error;
430         mutex_unlock(&ipcomp6_resource_mutex);
431
432         if (x->props.mode == XFRM_MODE_TUNNEL) {
433                 err = ipcomp6_tunnel_attach(x);
434                 if (err)
435                         goto error_tunnel;
436         }
437
438         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
439         BUG_ON(!calg_desc);
440         ipcd->threshold = calg_desc->uinfo.comp.threshold;
441         x->data = ipcd;
442         err = 0;
443 out:
444         return err;
445 error_tunnel:
446         mutex_lock(&ipcomp6_resource_mutex);
447 error:
448         ipcomp6_free_data(ipcd);
449         mutex_unlock(&ipcomp6_resource_mutex);
450         kfree(ipcd);
451
452         goto out;
453 }
454
455 static struct xfrm_type ipcomp6_type = 
456 {
457         .description    = "IPCOMP6",
458         .owner          = THIS_MODULE,
459         .proto          = IPPROTO_COMP,
460         .init_state     = ipcomp6_init_state,
461         .destructor     = ipcomp6_destroy,
462         .input          = ipcomp6_input,
463         .output         = ipcomp6_output,
464 };
465
466 static struct inet6_protocol ipcomp6_protocol = 
467 {
468         .handler        = xfrm6_rcv,
469         .err_handler    = ipcomp6_err,
470         .flags          = INET6_PROTO_NOPOLICY,
471 };
472
473 static int __init ipcomp6_init(void)
474 {
475         if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
476                 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
477                 return -EAGAIN;
478         }
479         if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
480                 printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
481                 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
482                 return -EAGAIN;
483         }
484         return 0;
485 }
486
487 static void __exit ipcomp6_fini(void)
488 {
489         if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) 
490                 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
491         if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
492                 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
493 }
494
495 module_init(ipcomp6_init);
496 module_exit(ipcomp6_fini);
497 MODULE_LICENSE("GPL");
498 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
499 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
500
501