xref: /openbmc/linux/net/ipv6/ipcomp6.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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 = ipv6_hdr(skb);
83 	ipch = (void *)skb->data;
84 	skb->transport_header = skb->network_header + 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 	skb_copy_to_linear_data(skb, 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 	struct ipv6_comp_hdr *ipch;
128 	struct ipcomp_data *ipcd = x->data;
129 	int plen, dlen;
130 	u8 *start, *scratch;
131 	struct crypto_comp *tfm;
132 	int cpu;
133 	int hdr_len = skb_transport_offset(skb);
134 
135 	/* check whether datagram len is larger than threshold */
136 	if ((skb->len - hdr_len) < ipcd->threshold) {
137 		goto out_ok;
138 	}
139 
140 	if (skb_linearize_cow(skb))
141 		goto out_ok;
142 
143 	/* compression */
144 	plen = skb->len - hdr_len;
145 	dlen = IPCOMP_SCRATCH_SIZE;
146 	start = skb_transport_header(skb);
147 
148 	cpu = get_cpu();
149 	scratch = *per_cpu_ptr(ipcomp6_scratches, cpu);
150 	tfm = *per_cpu_ptr(ipcd->tfms, cpu);
151 
152 	err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
153 	if (err || (dlen + sizeof(struct ipv6_comp_hdr)) >= plen) {
154 		put_cpu();
155 		goto out_ok;
156 	}
157 	memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
158 	put_cpu();
159 	pskb_trim(skb, hdr_len + dlen + sizeof(struct ip_comp_hdr));
160 
161 	/* insert ipcomp header and replace datagram */
162 	top_iph = (struct ipv6hdr *)skb->data;
163 
164 	top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
165 
166 	ipch = (struct ipv6_comp_hdr *)start;
167 	ipch->nexthdr = *skb_network_header(skb);
168 	ipch->flags = 0;
169 	ipch->cpi = htons((u16 )ntohl(x->id.spi));
170 	*skb_network_header(skb) = IPPROTO_COMP;
171 
172 out_ok:
173 	return 0;
174 }
175 
176 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
177 				int type, int code, int offset, __be32 info)
178 {
179 	__be32 spi;
180 	struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
181 	struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset);
182 	struct xfrm_state *x;
183 
184 	if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)
185 		return;
186 
187 	spi = htonl(ntohs(ipcomph->cpi));
188 	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
189 	if (!x)
190 		return;
191 
192 	printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIP6_FMT "\n",
193 			spi, NIP6(iph->daddr));
194 	xfrm_state_put(x);
195 }
196 
197 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
198 {
199 	struct xfrm_state *t = NULL;
200 	u8 mode = XFRM_MODE_TUNNEL;
201 
202 	t = xfrm_state_alloc();
203 	if (!t)
204 		goto out;
205 
206 	t->id.proto = IPPROTO_IPV6;
207 	t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);
208 	if (!t->id.spi)
209 		goto error;
210 
211 	memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
212 	memcpy(&t->sel, &x->sel, sizeof(t->sel));
213 	t->props.family = AF_INET6;
214 	if (x->props.mode == XFRM_MODE_BEET)
215 		mode = x->props.mode;
216 	t->props.mode = mode;
217 	memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
218 
219 	if (xfrm_init_state(t))
220 		goto error;
221 
222 	atomic_set(&t->tunnel_users, 1);
223 
224 out:
225 	return t;
226 
227 error:
228 	t->km.state = XFRM_STATE_DEAD;
229 	xfrm_state_put(t);
230 	t = NULL;
231 	goto out;
232 }
233 
234 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
235 {
236 	int err = 0;
237 	struct xfrm_state *t = NULL;
238 	__be32 spi;
239 
240 	spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
241 	if (spi)
242 		t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
243 					      spi, IPPROTO_IPV6, AF_INET6);
244 	if (!t) {
245 		t = ipcomp6_tunnel_create(x);
246 		if (!t) {
247 			err = -EINVAL;
248 			goto out;
249 		}
250 		xfrm_state_insert(t);
251 		xfrm_state_hold(t);
252 	}
253 	x->tunnel = t;
254 	atomic_inc(&t->tunnel_users);
255 
256 out:
257 	return err;
258 }
259 
260 static void ipcomp6_free_scratches(void)
261 {
262 	int i;
263 	void **scratches;
264 
265 	if (--ipcomp6_scratch_users)
266 		return;
267 
268 	scratches = ipcomp6_scratches;
269 	if (!scratches)
270 		return;
271 
272 	for_each_possible_cpu(i) {
273 		void *scratch = *per_cpu_ptr(scratches, i);
274 
275 		vfree(scratch);
276 	}
277 
278 	free_percpu(scratches);
279 }
280 
281 static void **ipcomp6_alloc_scratches(void)
282 {
283 	int i;
284 	void **scratches;
285 
286 	if (ipcomp6_scratch_users++)
287 		return ipcomp6_scratches;
288 
289 	scratches = alloc_percpu(void *);
290 	if (!scratches)
291 		return NULL;
292 
293 	ipcomp6_scratches = scratches;
294 
295 	for_each_possible_cpu(i) {
296 		void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
297 		if (!scratch)
298 			return NULL;
299 		*per_cpu_ptr(scratches, i) = scratch;
300 	}
301 
302 	return scratches;
303 }
304 
305 static void ipcomp6_free_tfms(struct crypto_comp **tfms)
306 {
307 	struct ipcomp6_tfms *pos;
308 	int cpu;
309 
310 	list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
311 		if (pos->tfms == tfms)
312 			break;
313 	}
314 
315 	BUG_TRAP(pos);
316 
317 	if (--pos->users)
318 		return;
319 
320 	list_del(&pos->list);
321 	kfree(pos);
322 
323 	if (!tfms)
324 		return;
325 
326 	for_each_possible_cpu(cpu) {
327 		struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
328 		crypto_free_comp(tfm);
329 	}
330 	free_percpu(tfms);
331 }
332 
333 static struct crypto_comp **ipcomp6_alloc_tfms(const char *alg_name)
334 {
335 	struct ipcomp6_tfms *pos;
336 	struct crypto_comp **tfms;
337 	int cpu;
338 
339 	/* This can be any valid CPU ID so we don't need locking. */
340 	cpu = raw_smp_processor_id();
341 
342 	list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
343 		struct crypto_comp *tfm;
344 
345 		tfms = pos->tfms;
346 		tfm = *per_cpu_ptr(tfms, cpu);
347 
348 		if (!strcmp(crypto_comp_name(tfm), alg_name)) {
349 			pos->users++;
350 			return tfms;
351 		}
352 	}
353 
354 	pos = kmalloc(sizeof(*pos), GFP_KERNEL);
355 	if (!pos)
356 		return NULL;
357 
358 	pos->users = 1;
359 	INIT_LIST_HEAD(&pos->list);
360 	list_add(&pos->list, &ipcomp6_tfms_list);
361 
362 	pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
363 	if (!tfms)
364 		goto error;
365 
366 	for_each_possible_cpu(cpu) {
367 		struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
368 							    CRYPTO_ALG_ASYNC);
369 		if (!tfm)
370 			goto error;
371 		*per_cpu_ptr(tfms, cpu) = tfm;
372 	}
373 
374 	return tfms;
375 
376 error:
377 	ipcomp6_free_tfms(tfms);
378 	return NULL;
379 }
380 
381 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
382 {
383 	if (ipcd->tfms)
384 		ipcomp6_free_tfms(ipcd->tfms);
385 	ipcomp6_free_scratches();
386 }
387 
388 static void ipcomp6_destroy(struct xfrm_state *x)
389 {
390 	struct ipcomp_data *ipcd = x->data;
391 	if (!ipcd)
392 		return;
393 	xfrm_state_delete_tunnel(x);
394 	mutex_lock(&ipcomp6_resource_mutex);
395 	ipcomp6_free_data(ipcd);
396 	mutex_unlock(&ipcomp6_resource_mutex);
397 	kfree(ipcd);
398 
399 	xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
400 }
401 
402 static int ipcomp6_init_state(struct xfrm_state *x)
403 {
404 	int err;
405 	struct ipcomp_data *ipcd;
406 	struct xfrm_algo_desc *calg_desc;
407 
408 	err = -EINVAL;
409 	if (!x->calg)
410 		goto out;
411 
412 	if (x->encap)
413 		goto out;
414 
415 	err = -ENOMEM;
416 	ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
417 	if (!ipcd)
418 		goto out;
419 
420 	x->props.header_len = 0;
421 	if (x->props.mode == XFRM_MODE_TUNNEL)
422 		x->props.header_len += sizeof(struct ipv6hdr);
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 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 
504