xref: /openbmc/linux/net/ipv6/ipcomp6.c (revision 643d1f7f)
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/semaphore.h>
38 #include <linux/crypto.h>
39 #include <linux/err.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 nexthdr;
68 	int err = -ENOMEM;
69 	struct ip_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 	ipch = (void *)skb->data;
83 	nexthdr = ipch->nexthdr;
84 
85 	skb->transport_header = skb->network_header + 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 		goto out_put_cpu;
100 
101 	if (dlen < (plen + sizeof(*ipch))) {
102 		err = -EINVAL;
103 		goto out_put_cpu;
104 	}
105 
106 	err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
107 	if (err) {
108 		goto out_put_cpu;
109 	}
110 
111 	skb->truesize += dlen - plen;
112 	__skb_put(skb, dlen - plen);
113 	skb_copy_to_linear_data(skb, scratch, dlen);
114 	err = nexthdr;
115 
116 out_put_cpu:
117 	put_cpu();
118 out:
119 	return err;
120 }
121 
122 static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb)
123 {
124 	int err;
125 	struct ip_comp_hdr *ipch;
126 	struct ipcomp_data *ipcd = x->data;
127 	int plen, dlen;
128 	u8 *start, *scratch;
129 	struct crypto_comp *tfm;
130 	int cpu;
131 
132 	/* check whether datagram len is larger than threshold */
133 	if (skb->len < ipcd->threshold) {
134 		goto out_ok;
135 	}
136 
137 	if (skb_linearize_cow(skb))
138 		goto out_ok;
139 
140 	/* compression */
141 	plen = skb->len;
142 	dlen = IPCOMP_SCRATCH_SIZE;
143 	start = skb->data;
144 
145 	cpu = get_cpu();
146 	scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
147 	tfm = *per_cpu_ptr(ipcd->tfms, cpu);
148 
149 	err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
150 	if (err || (dlen + sizeof(*ipch)) >= plen) {
151 		put_cpu();
152 		goto out_ok;
153 	}
154 	memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
155 	put_cpu();
156 	pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
157 
158 	/* insert ipcomp header and replace datagram */
159 	ipch = ip_comp_hdr(skb);
160 	ipch->nexthdr = *skb_mac_header(skb);
161 	ipch->flags = 0;
162 	ipch->cpi = htons((u16 )ntohl(x->id.spi));
163 	*skb_mac_header(skb) = IPPROTO_COMP;
164 
165 out_ok:
166 	skb_push(skb, -skb_network_offset(skb));
167 
168 	return 0;
169 }
170 
171 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
172 				int type, int code, int offset, __be32 info)
173 {
174 	__be32 spi;
175 	struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
176 	struct ip_comp_hdr *ipcomph =
177 		(struct ip_comp_hdr *)(skb->data + offset);
178 	struct xfrm_state *x;
179 
180 	if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
181 		return;
182 
183 	spi = htonl(ntohs(ipcomph->cpi));
184 	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
185 	if (!x)
186 		return;
187 
188 	printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n",
189 			spi, NIP6(iph->daddr));
190 	xfrm_state_put(x);
191 }
192 
193 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
194 {
195 	struct xfrm_state *t = NULL;
196 
197 	t = xfrm_state_alloc();
198 	if (!t)
199 		goto out;
200 
201 	t->id.proto = IPPROTO_IPV6;
202 	t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
203 	if (!t->id.spi)
204 		goto error;
205 
206 	memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
207 	memcpy(&t->sel, &x->sel, sizeof(t->sel));
208 	t->props.family = AF_INET6;
209 	t->props.mode = x->props.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 (IS_ERR(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 	x->props.header_len = 0;
409 	switch (x->props.mode) {
410 	case XFRM_MODE_TRANSPORT:
411 		break;
412 	case XFRM_MODE_TUNNEL:
413 		x->props.header_len += sizeof(struct ipv6hdr);
414 		break;
415 	default:
416 		goto out;
417 	}
418 
419 	err = -ENOMEM;
420 	ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
421 	if (!ipcd)
422 		goto out;
423 
424 	mutex_lock(&ipcomp6_resource_mutex);
425 	if (!ipcomp6_alloc_scratches())
426 		goto error;
427 
428 	ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
429 	if (!ipcd->tfms)
430 		goto error;
431 	mutex_unlock(&ipcomp6_resource_mutex);
432 
433 	if (x->props.mode == XFRM_MODE_TUNNEL) {
434 		err = ipcomp6_tunnel_attach(x);
435 		if (err)
436 			goto error_tunnel;
437 	}
438 
439 	calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
440 	BUG_ON(!calg_desc);
441 	ipcd->threshold = calg_desc->uinfo.comp.threshold;
442 	x->data = ipcd;
443 	err = 0;
444 out:
445 	return err;
446 error_tunnel:
447 	mutex_lock(&ipcomp6_resource_mutex);
448 error:
449 	ipcomp6_free_data(ipcd);
450 	mutex_unlock(&ipcomp6_resource_mutex);
451 	kfree(ipcd);
452 
453 	goto out;
454 }
455 
456 static const struct xfrm_type ipcomp6_type =
457 {
458 	.description	= "IPCOMP6",
459 	.owner		= THIS_MODULE,
460 	.proto		= IPPROTO_COMP,
461 	.init_state	= ipcomp6_init_state,
462 	.destructor	= ipcomp6_destroy,
463 	.input		= ipcomp6_input,
464 	.output		= ipcomp6_output,
465 	.hdr_offset	= xfrm6_find_1stfragopt,
466 };
467 
468 static struct inet6_protocol ipcomp6_protocol =
469 {
470 	.handler	= xfrm6_rcv,
471 	.err_handler	= ipcomp6_err,
472 	.flags		= INET6_PROTO_NOPOLICY,
473 };
474 
475 static int __init ipcomp6_init(void)
476 {
477 	if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
478 		printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
479 		return -EAGAIN;
480 	}
481 	if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
482 		printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
483 		xfrm_unregister_type(&ipcomp6_type, AF_INET6);
484 		return -EAGAIN;
485 	}
486 	return 0;
487 }
488 
489 static void __exit ipcomp6_fini(void)
490 {
491 	if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
492 		printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
493 	if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
494 		printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
495 }
496 
497 module_init(ipcomp6_init);
498 module_exit(ipcomp6_fini);
499 MODULE_LICENSE("GPL");
500 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
501 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
502 
503 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);
504