Linux-2.6.12-rc2
[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/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 <linux/ipv6.h>
51 #include <linux/icmpv6.h>
52
53 struct ipcomp6_tfms {
54         struct list_head list;
55         struct crypto_tfm **tfms;
56         int users;
57 };
58
59 static DECLARE_MUTEX(ipcomp6_resource_sem);
60 static void **ipcomp6_scratches;
61 static int ipcomp6_scratch_users;
62 static LIST_HEAD(ipcomp6_tfms_list);
63
64 static int ipcomp6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
65 {
66         int err = 0;
67         u8 nexthdr = 0;
68         int hdr_len = skb->h.raw - skb->nh.raw;
69         unsigned char *tmp_hdr = NULL;
70         struct ipv6hdr *iph;
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_is_nonlinear(skb) || skb_cloned(skb)) &&
78                 skb_linearize(skb, GFP_ATOMIC) != 0) {
79                 err = -ENOMEM;
80                 goto out;
81         }
82
83         skb->ip_summed = CHECKSUM_NONE;
84
85         /* Remove ipcomp header and decompress original payload */
86         iph = skb->nh.ipv6h;
87         tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
88         if (!tmp_hdr)
89                 goto out;
90         memcpy(tmp_hdr, iph, hdr_len);
91         nexthdr = *(u8 *)skb->data;
92         skb_pull(skb, sizeof(struct ipv6_comp_hdr)); 
93         skb->nh.raw += sizeof(struct ipv6_comp_hdr);
94         memcpy(skb->nh.raw, tmp_hdr, hdr_len);
95         iph = skb->nh.ipv6h;
96         iph->payload_len = htons(ntohs(iph->payload_len) - sizeof(struct ipv6_comp_hdr));
97         skb->h.raw = skb->data;
98
99         /* decompression */
100         plen = skb->len;
101         dlen = IPCOMP_SCRATCH_SIZE;
102         start = skb->data;
103
104         cpu = get_cpu();
105         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
106         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
107
108         err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
109         if (err) {
110                 err = -EINVAL;
111                 goto out_put_cpu;
112         }
113
114         if (dlen < (plen + sizeof(struct ipv6_comp_hdr))) {
115                 err = -EINVAL;
116                 goto out_put_cpu;
117         }
118
119         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
120         if (err) {
121                 goto out_put_cpu;
122         }
123
124         skb_put(skb, dlen - plen);
125         memcpy(skb->data, scratch, dlen);
126
127         iph = skb->nh.ipv6h;
128         iph->payload_len = htons(skb->len);
129         
130 out_put_cpu:
131         put_cpu();
132 out:
133         if (tmp_hdr)
134                 kfree(tmp_hdr);
135         if (err)
136                 goto error_out;
137         return nexthdr;
138 error_out:
139         return err;
140 }
141
142 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb)
143 {
144         int err;
145         struct ipv6hdr *top_iph;
146         int hdr_len;
147         struct ipv6_comp_hdr *ipch;
148         struct ipcomp_data *ipcd = x->data;
149         int plen, dlen;
150         u8 *start, *scratch;
151         struct crypto_tfm *tfm;
152         int cpu;
153
154         hdr_len = skb->h.raw - skb->data;
155
156         /* check whether datagram len is larger than threshold */
157         if ((skb->len - hdr_len) < ipcd->threshold) {
158                 goto out_ok;
159         }
160
161         if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
162                 skb_linearize(skb, GFP_ATOMIC) != 0) {
163                 goto out_ok;
164         }
165
166         /* compression */
167         plen = skb->len - hdr_len;
168         dlen = IPCOMP_SCRATCH_SIZE;
169         start = skb->h.raw;
170
171         cpu = get_cpu();
172         scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
173         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
174
175         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
176         if (err || (dlen + sizeof(struct ipv6_comp_hdr)) >= plen) {
177                 put_cpu();
178                 goto out_ok;
179         }
180         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
181         put_cpu();
182         pskb_trim(skb, hdr_len + dlen + sizeof(struct ip_comp_hdr));
183
184         /* insert ipcomp header and replace datagram */
185         top_iph = (struct ipv6hdr *)skb->data;
186
187         top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
188
189         ipch = (struct ipv6_comp_hdr *)start;
190         ipch->nexthdr = *skb->nh.raw;
191         ipch->flags = 0;
192         ipch->cpi = htons((u16 )ntohl(x->id.spi));
193         *skb->nh.raw = IPPROTO_COMP;
194
195 out_ok:
196         return 0;
197 }
198
199 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
200                                 int type, int code, int offset, __u32 info)
201 {
202         u32 spi;
203         struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
204         struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset);
205         struct xfrm_state *x;
206
207         if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
208                 return;
209
210         spi = ntohl(ntohs(ipcomph->cpi));
211         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
212         if (!x)
213                 return;
214
215         printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/"
216                         "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n",
217                         spi, NIP6(iph->daddr));
218         xfrm_state_put(x);
219 }
220
221 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
222 {
223         struct xfrm_state *t = NULL;
224
225         t = xfrm_state_alloc();
226         if (!t)
227                 goto out;
228
229         t->id.proto = IPPROTO_IPV6;
230         t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
231         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
232         memcpy(&t->sel, &x->sel, sizeof(t->sel));
233         t->props.family = AF_INET6;
234         t->props.mode = 1;
235         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
236
237         t->type = xfrm_get_type(IPPROTO_IPV6, t->props.family);
238         if (t->type == NULL)
239                 goto error;
240
241         if (t->type->init_state(t, NULL))
242                 goto error;
243
244         t->km.state = XFRM_STATE_VALID;
245         atomic_set(&t->tunnel_users, 1);
246
247 out:
248         return t;
249
250 error:
251         xfrm_state_put(t);
252         goto out;
253 }
254
255 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
256 {
257         int err = 0;
258         struct xfrm_state *t = NULL;
259         u32 spi;
260
261         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
262         if (spi)
263                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
264                                               spi, IPPROTO_IPV6, AF_INET6);
265         if (!t) {
266                 t = ipcomp6_tunnel_create(x);
267                 if (!t) {
268                         err = -EINVAL;
269                         goto out;
270                 }
271                 xfrm_state_insert(t);
272                 xfrm_state_hold(t);
273         }
274         x->tunnel = t;
275         atomic_inc(&t->tunnel_users);
276
277 out:
278         return err;
279 }
280
281 static void ipcomp6_free_scratches(void)
282 {
283         int i;
284         void **scratches;
285
286         if (--ipcomp6_scratch_users)
287                 return;
288
289         scratches = ipcomp6_scratches;
290         if (!scratches)
291                 return;
292
293         for_each_cpu(i) {
294                 void *scratch = *per_cpu_ptr(scratches, i);
295                 if (scratch)
296                         vfree(scratch);
297         }
298
299         free_percpu(scratches);
300 }
301
302 static void **ipcomp6_alloc_scratches(void)
303 {
304         int i;
305         void **scratches;
306
307         if (ipcomp6_scratch_users++)
308                 return ipcomp6_scratches;
309
310         scratches = alloc_percpu(void *);
311         if (!scratches)
312                 return NULL;
313
314         ipcomp6_scratches = scratches;
315
316         for_each_cpu(i) {
317                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
318                 if (!scratch)
319                         return NULL;
320                 *per_cpu_ptr(scratches, i) = scratch;
321         }
322
323         return scratches;
324 }
325
326 static void ipcomp6_free_tfms(struct crypto_tfm **tfms)
327 {
328         struct ipcomp6_tfms *pos;
329         int cpu;
330
331         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
332                 if (pos->tfms == tfms)
333                         break;
334         }
335
336         BUG_TRAP(pos);
337
338         if (--pos->users)
339                 return;
340
341         list_del(&pos->list);
342         kfree(pos);
343
344         if (!tfms)
345                 return;
346
347         for_each_cpu(cpu) {
348                 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu);
349                 if (tfm)
350                         crypto_free_tfm(tfm);
351         }
352         free_percpu(tfms);
353 }
354
355 static struct crypto_tfm **ipcomp6_alloc_tfms(const char *alg_name)
356 {
357         struct ipcomp6_tfms *pos;
358         struct crypto_tfm **tfms;
359         int cpu;
360
361         /* This can be any valid CPU ID so we don't need locking. */
362         cpu = smp_processor_id();
363
364         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
365                 struct crypto_tfm *tfm;
366
367                 tfms = pos->tfms;
368                 tfm = *per_cpu_ptr(tfms, cpu);
369
370                 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) {
371                         pos->users++;
372                         return tfms;
373                 }
374         }
375
376         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
377         if (!pos)
378                 return NULL;
379
380         pos->users = 1;
381         INIT_LIST_HEAD(&pos->list);
382         list_add(&pos->list, &ipcomp6_tfms_list);
383
384         pos->tfms = tfms = alloc_percpu(struct crypto_tfm *);
385         if (!tfms)
386                 goto error;
387
388         for_each_cpu(cpu) {
389                 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0);
390                 if (!tfm)
391                         goto error;
392                 *per_cpu_ptr(tfms, cpu) = tfm;
393         }
394
395         return tfms;
396
397 error:
398         ipcomp6_free_tfms(tfms);
399         return NULL;
400 }
401
402 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
403 {
404         if (ipcd->tfms)
405                 ipcomp6_free_tfms(ipcd->tfms);
406         ipcomp6_free_scratches();
407 }
408
409 static void ipcomp6_destroy(struct xfrm_state *x)
410 {
411         struct ipcomp_data *ipcd = x->data;
412         if (!ipcd)
413                 return;
414         xfrm_state_delete_tunnel(x);
415         down(&ipcomp6_resource_sem);
416         ipcomp6_free_data(ipcd);
417         up(&ipcomp6_resource_sem);
418         kfree(ipcd);
419
420         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
421 }
422
423 static int ipcomp6_init_state(struct xfrm_state *x, void *args)
424 {
425         int err;
426         struct ipcomp_data *ipcd;
427         struct xfrm_algo_desc *calg_desc;
428
429         err = -EINVAL;
430         if (!x->calg)
431                 goto out;
432
433         if (x->encap)
434                 goto out;
435
436         err = -ENOMEM;
437         ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL);
438         if (!ipcd)
439                 goto out;
440
441         memset(ipcd, 0, sizeof(*ipcd));
442         x->props.header_len = 0;
443         if (x->props.mode)
444                 x->props.header_len += sizeof(struct ipv6hdr);
445         
446         down(&ipcomp6_resource_sem);
447         if (!ipcomp6_alloc_scratches())
448                 goto error;
449
450         ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
451         if (!ipcd->tfms)
452                 goto error;
453         up(&ipcomp6_resource_sem);
454
455         if (x->props.mode) {
456                 err = ipcomp6_tunnel_attach(x);
457                 if (err)
458                         goto error_tunnel;
459         }
460
461         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
462         BUG_ON(!calg_desc);
463         ipcd->threshold = calg_desc->uinfo.comp.threshold;
464         x->data = ipcd;
465         err = 0;
466 out:
467         return err;
468 error_tunnel:
469         down(&ipcomp6_resource_sem);
470 error:
471         ipcomp6_free_data(ipcd);
472         up(&ipcomp6_resource_sem);
473         kfree(ipcd);
474
475         goto out;
476 }
477
478 static struct xfrm_type ipcomp6_type = 
479 {
480         .description    = "IPCOMP6",
481         .owner          = THIS_MODULE,
482         .proto          = IPPROTO_COMP,
483         .init_state     = ipcomp6_init_state,
484         .destructor     = ipcomp6_destroy,
485         .input          = ipcomp6_input,
486         .output         = ipcomp6_output,
487 };
488
489 static struct inet6_protocol ipcomp6_protocol = 
490 {
491         .handler        = xfrm6_rcv,
492         .err_handler    = ipcomp6_err,
493         .flags          = INET6_PROTO_NOPOLICY,
494 };
495
496 static int __init ipcomp6_init(void)
497 {
498         if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
499                 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
500                 return -EAGAIN;
501         }
502         if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
503                 printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
504                 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
505                 return -EAGAIN;
506         }
507         return 0;
508 }
509
510 static void __exit ipcomp6_fini(void)
511 {
512         if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) 
513                 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
514         if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
515                 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
516 }
517
518 module_init(ipcomp6_init);
519 module_exit(ipcomp6_fini);
520 MODULE_LICENSE("GPL");
521 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
522 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
523
524