xref: /openbmc/linux/net/ipv6/ipcomp6.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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 	if (xfrm_init_state(t))
238 		goto error;
239 
240 	atomic_set(&t->tunnel_users, 1);
241 
242 out:
243 	return t;
244 
245 error:
246 	xfrm_state_put(t);
247 	goto out;
248 }
249 
250 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
251 {
252 	int err = 0;
253 	struct xfrm_state *t = NULL;
254 	u32 spi;
255 
256 	spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);
257 	if (spi)
258 		t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr,
259 					      spi, IPPROTO_IPV6, AF_INET6);
260 	if (!t) {
261 		t = ipcomp6_tunnel_create(x);
262 		if (!t) {
263 			err = -EINVAL;
264 			goto out;
265 		}
266 		xfrm_state_insert(t);
267 		xfrm_state_hold(t);
268 	}
269 	x->tunnel = t;
270 	atomic_inc(&t->tunnel_users);
271 
272 out:
273 	return err;
274 }
275 
276 static void ipcomp6_free_scratches(void)
277 {
278 	int i;
279 	void **scratches;
280 
281 	if (--ipcomp6_scratch_users)
282 		return;
283 
284 	scratches = ipcomp6_scratches;
285 	if (!scratches)
286 		return;
287 
288 	for_each_cpu(i) {
289 		void *scratch = *per_cpu_ptr(scratches, i);
290 		if (scratch)
291 			vfree(scratch);
292 	}
293 
294 	free_percpu(scratches);
295 }
296 
297 static void **ipcomp6_alloc_scratches(void)
298 {
299 	int i;
300 	void **scratches;
301 
302 	if (ipcomp6_scratch_users++)
303 		return ipcomp6_scratches;
304 
305 	scratches = alloc_percpu(void *);
306 	if (!scratches)
307 		return NULL;
308 
309 	ipcomp6_scratches = scratches;
310 
311 	for_each_cpu(i) {
312 		void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
313 		if (!scratch)
314 			return NULL;
315 		*per_cpu_ptr(scratches, i) = scratch;
316 	}
317 
318 	return scratches;
319 }
320 
321 static void ipcomp6_free_tfms(struct crypto_tfm **tfms)
322 {
323 	struct ipcomp6_tfms *pos;
324 	int cpu;
325 
326 	list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
327 		if (pos->tfms == tfms)
328 			break;
329 	}
330 
331 	BUG_TRAP(pos);
332 
333 	if (--pos->users)
334 		return;
335 
336 	list_del(&pos->list);
337 	kfree(pos);
338 
339 	if (!tfms)
340 		return;
341 
342 	for_each_cpu(cpu) {
343 		struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu);
344 		crypto_free_tfm(tfm);
345 	}
346 	free_percpu(tfms);
347 }
348 
349 static struct crypto_tfm **ipcomp6_alloc_tfms(const char *alg_name)
350 {
351 	struct ipcomp6_tfms *pos;
352 	struct crypto_tfm **tfms;
353 	int cpu;
354 
355 	/* This can be any valid CPU ID so we don't need locking. */
356 	cpu = raw_smp_processor_id();
357 
358 	list_for_each_entry(pos, &ipcomp6_tfms_list, list) {
359 		struct crypto_tfm *tfm;
360 
361 		tfms = pos->tfms;
362 		tfm = *per_cpu_ptr(tfms, cpu);
363 
364 		if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) {
365 			pos->users++;
366 			return tfms;
367 		}
368 	}
369 
370 	pos = kmalloc(sizeof(*pos), GFP_KERNEL);
371 	if (!pos)
372 		return NULL;
373 
374 	pos->users = 1;
375 	INIT_LIST_HEAD(&pos->list);
376 	list_add(&pos->list, &ipcomp6_tfms_list);
377 
378 	pos->tfms = tfms = alloc_percpu(struct crypto_tfm *);
379 	if (!tfms)
380 		goto error;
381 
382 	for_each_cpu(cpu) {
383 		struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0);
384 		if (!tfm)
385 			goto error;
386 		*per_cpu_ptr(tfms, cpu) = tfm;
387 	}
388 
389 	return tfms;
390 
391 error:
392 	ipcomp6_free_tfms(tfms);
393 	return NULL;
394 }
395 
396 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
397 {
398 	if (ipcd->tfms)
399 		ipcomp6_free_tfms(ipcd->tfms);
400 	ipcomp6_free_scratches();
401 }
402 
403 static void ipcomp6_destroy(struct xfrm_state *x)
404 {
405 	struct ipcomp_data *ipcd = x->data;
406 	if (!ipcd)
407 		return;
408 	xfrm_state_delete_tunnel(x);
409 	down(&ipcomp6_resource_sem);
410 	ipcomp6_free_data(ipcd);
411 	up(&ipcomp6_resource_sem);
412 	kfree(ipcd);
413 
414 	xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);
415 }
416 
417 static int ipcomp6_init_state(struct xfrm_state *x)
418 {
419 	int err;
420 	struct ipcomp_data *ipcd;
421 	struct xfrm_algo_desc *calg_desc;
422 
423 	err = -EINVAL;
424 	if (!x->calg)
425 		goto out;
426 
427 	if (x->encap)
428 		goto out;
429 
430 	err = -ENOMEM;
431 	ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL);
432 	if (!ipcd)
433 		goto out;
434 
435 	memset(ipcd, 0, sizeof(*ipcd));
436 	x->props.header_len = 0;
437 	if (x->props.mode)
438 		x->props.header_len += sizeof(struct ipv6hdr);
439 
440 	down(&ipcomp6_resource_sem);
441 	if (!ipcomp6_alloc_scratches())
442 		goto error;
443 
444 	ipcd->tfms = ipcomp6_alloc_tfms(x->calg->alg_name);
445 	if (!ipcd->tfms)
446 		goto error;
447 	up(&ipcomp6_resource_sem);
448 
449 	if (x->props.mode) {
450 		err = ipcomp6_tunnel_attach(x);
451 		if (err)
452 			goto error_tunnel;
453 	}
454 
455 	calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
456 	BUG_ON(!calg_desc);
457 	ipcd->threshold = calg_desc->uinfo.comp.threshold;
458 	x->data = ipcd;
459 	err = 0;
460 out:
461 	return err;
462 error_tunnel:
463 	down(&ipcomp6_resource_sem);
464 error:
465 	ipcomp6_free_data(ipcd);
466 	up(&ipcomp6_resource_sem);
467 	kfree(ipcd);
468 
469 	goto out;
470 }
471 
472 static struct xfrm_type ipcomp6_type =
473 {
474 	.description	= "IPCOMP6",
475 	.owner		= THIS_MODULE,
476 	.proto		= IPPROTO_COMP,
477 	.init_state	= ipcomp6_init_state,
478 	.destructor	= ipcomp6_destroy,
479 	.input		= ipcomp6_input,
480 	.output		= ipcomp6_output,
481 };
482 
483 static struct inet6_protocol ipcomp6_protocol =
484 {
485 	.handler	= xfrm6_rcv,
486 	.err_handler	= ipcomp6_err,
487 	.flags		= INET6_PROTO_NOPOLICY,
488 };
489 
490 static int __init ipcomp6_init(void)
491 {
492 	if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
493 		printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
494 		return -EAGAIN;
495 	}
496 	if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
497 		printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
498 		xfrm_unregister_type(&ipcomp6_type, AF_INET6);
499 		return -EAGAIN;
500 	}
501 	return 0;
502 }
503 
504 static void __exit ipcomp6_fini(void)
505 {
506 	if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
507 		printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
508 	if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
509 		printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
510 }
511 
512 module_init(ipcomp6_init);
513 module_exit(ipcomp6_fini);
514 MODULE_LICENSE("GPL");
515 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
516 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
517 
518 
519