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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, __be32 info)
180 {
181         __be32 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         u8 mode = XFRM_MODE_TUNNEL;
203
204         t = xfrm_state_alloc();
205         if (!t)
206                 goto out;
207
208         t->id.proto = IPPROTO_IPV6;
209         t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
210         if (!t->id.spi)
211                 goto error;
212
213         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
214         memcpy(&t->sel, &x->sel, sizeof(t->sel));
215         t->props.family = AF_INET6;
216         if (x->props.mode == XFRM_MODE_BEET)
217                 mode = x->props.mode;
218         t->props.mode = mode;
219         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
220
221         if (xfrm_init_state(t))
222                 goto error;
223
224         atomic_set(&t->tunnel_users, 1);
225
226 out:
227         return t;
228
229 error:
230         t->km.state = XFRM_STATE_DEAD;
231         xfrm_state_put(t);
232         t = NULL;
233         goto out;
234 }
235
236 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
237 {
238         int err = 0;
239         struct xfrm_state *t = NULL;
240         __be32 spi;
241
242         spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
243         if (spi)
244                 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
245                                               spi, IPPROTO_IPV6, AF_INET6);
246         if (!t) {
247                 t = ipcomp6_tunnel_create(x);
248                 if (!t) {
249                         err = -EINVAL;
250                         goto out;
251                 }
252                 xfrm_state_insert(t);
253                 xfrm_state_hold(t);
254         }
255         x->tunnel = t;
256         atomic_inc(&t->tunnel_users);
257
258 out:
259         return err;
260 }
261
262 static void ipcomp6_free_scratches(void)
263 {
264         int i;
265         void **scratches;
266
267         if (--ipcomp6_scratch_users)
268                 return;
269
270         scratches = ipcomp6_scratches;
271         if (!scratches)
272                 return;
273
274         for_each_possible_cpu(i) {
275                 void *scratch = *per_cpu_ptr(scratches, i);
276
277                 vfree(scratch);
278         }
279
280         free_percpu(scratches);
281 }
282
283 static void **ipcomp6_alloc_scratches(void)
284 {
285         int i;
286         void **scratches;
287
288         if (ipcomp6_scratch_users++)
289                 return ipcomp6_scratches;
290
291         scratches = alloc_percpu(void *);
292         if (!scratches)
293                 return NULL;
294
295         ipcomp6_scratches = scratches;
296
297         for_each_possible_cpu(i) {
298                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
299                 if (!scratch)
300                         return NULL;
301                 *per_cpu_ptr(scratches, i) = scratch;
302         }
303
304         return scratches;
305 }
306
307 static void ipcomp6_free_tfms(struct crypto_comp **tfms)
308 {
309         struct ipcomp6_tfms *pos;
310         int cpu;
311
312         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
313                 if (pos->tfms == tfms)
314                         break;
315         }
316
317         BUG_TRAP(pos);
318
319         if (--pos->users)
320                 return;
321
322         list_del(&pos->list);
323         kfree(pos);
324
325         if (!tfms)
326                 return;
327
328         for_each_possible_cpu(cpu) {
329                 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
330                 crypto_free_comp(tfm);
331         }
332         free_percpu(tfms);
333 }
334
335 static struct crypto_comp **ipcomp6_alloc_tfms(const char *alg_name)
336 {
337         struct ipcomp6_tfms *pos;
338         struct crypto_comp **tfms;
339         int cpu;
340
341         /* This can be any valid CPU ID so we don't need locking. */
342         cpu = raw_smp_processor_id();
343
344         list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
345                 struct crypto_comp *tfm;
346
347                 tfms = pos->tfms;
348                 tfm = *per_cpu_ptr(tfms, cpu);
349
350                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
351                         pos->users++;
352                         return tfms;
353                 }
354         }
355
356         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
357         if (!pos)
358                 return NULL;
359
360         pos->users = 1;
361         INIT_LIST_HEAD(&pos->list);
362         list_add(&pos->list, &ipcomp6_tfms_list);
363
364         pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
365         if (!tfms)
366                 goto error;
367
368         for_each_possible_cpu(cpu) {
369                 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
370                                                             CRYPTO_ALG_ASYNC);
371                 if (!tfm)
372                         goto error;
373                 *per_cpu_ptr(tfms, cpu) = tfm;
374         }
375
376         return tfms;
377
378 error:
379         ipcomp6_free_tfms(tfms);
380         return NULL;
381 }
382
383 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
384 {
385         if (ipcd->tfms)
386                 ipcomp6_free_tfms(ipcd->tfms);
387         ipcomp6_free_scratches();
388 }
389
390 static void ipcomp6_destroy(struct xfrm_state *x)
391 {
392         struct ipcomp_data *ipcd = x->data;
393         if (!ipcd)
394                 return;
395         xfrm_state_delete_tunnel(x);
396         mutex_lock(&ipcomp6_resource_mutex);
397         ipcomp6_free_data(ipcd);
398         mutex_unlock(&ipcomp6_resource_mutex);
399         kfree(ipcd);
400
401         xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
402 }
403
404 static int ipcomp6_init_state(struct xfrm_state *x)
405 {
406         int err;
407         struct ipcomp_data *ipcd;
408         struct xfrm_algo_desc *calg_desc;
409
410         err = -EINVAL;
411         if (!x->calg)
412                 goto out;
413
414         if (x->encap)
415                 goto out;
416
417         err = -ENOMEM;
418         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
419         if (!ipcd)
420                 goto out;
421
422         x->props.header_len = 0;
423         if (x->props.mode == XFRM_MODE_TUNNEL)
424                 x->props.header_len += sizeof(struct ipv6hdr);
425
426         mutex_lock(&ipcomp6_resource_mutex);
427         if (!ipcomp6_alloc_scratches())
428                 goto error;
429
430         ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
431         if (!ipcd->tfms)
432                 goto error;
433         mutex_unlock(&ipcomp6_resource_mutex);
434
435         if (x->props.mode == XFRM_MODE_TUNNEL) {
436                 err = ipcomp6_tunnel_attach(x);
437                 if (err)
438                         goto error_tunnel;
439         }
440
441         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
442         BUG_ON(!calg_desc);
443         ipcd->threshold = calg_desc->uinfo.comp.threshold;
444         x->data = ipcd;
445         err = 0;
446 out:
447         return err;
448 error_tunnel:
449         mutex_lock(&ipcomp6_resource_mutex);
450 error:
451         ipcomp6_free_data(ipcd);
452         mutex_unlock(&ipcomp6_resource_mutex);
453         kfree(ipcd);
454
455         goto out;
456 }
457
458 static struct xfrm_type ipcomp6_type =
459 {
460         .description    = "IPCOMP6",
461         .owner          = THIS_MODULE,
462         .proto          = IPPROTO_COMP,
463         .init_state     = ipcomp6_init_state,
464         .destructor     = ipcomp6_destroy,
465         .input          = ipcomp6_input,
466         .output         = ipcomp6_output,
467         .hdr_offset     = xfrm6_find_1stfragopt,
468 };
469
470 static struct inet6_protocol ipcomp6_protocol =
471 {
472         .handler        = xfrm6_rcv,
473         .err_handler    = ipcomp6_err,
474         .flags          = INET6_PROTO_NOPOLICY,
475 };
476
477 static int __init ipcomp6_init(void)
478 {
479         if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
480                 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
481                 return -EAGAIN;
482         }
483         if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
484                 printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
485                 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
486                 return -EAGAIN;
487         }
488         return 0;
489 }
490
491 static void __exit ipcomp6_fini(void)
492 {
493         if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
494                 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
495         if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
496                 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
497 }
498
499 module_init(ipcomp6_init);
500 module_exit(ipcomp6_fini);
501 MODULE_LICENSE("GPL");
502 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
503 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
504
505