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1da177e4 LT |
1 | /* |
2 | * IP Payload Compression Protocol (IPComp) - RFC3173. | |
3 | * | |
4 | * Copyright (c) 2003 James Morris <jmorris@intercode.com.au> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify it | |
7 | * under the terms of the GNU General Public License as published by the Free | |
8 | * Software Foundation; either version 2 of the License, or (at your option) | |
9 | * any later version. | |
10 | * | |
11 | * Todo: | |
12 | * - Tunable compression parameters. | |
13 | * - Compression stats. | |
14 | * - Adaptive compression. | |
15 | */ | |
16 | #include <linux/config.h> | |
17 | #include <linux/module.h> | |
18 | #include <asm/scatterlist.h> | |
19 | #include <asm/semaphore.h> | |
20 | #include <linux/crypto.h> | |
21 | #include <linux/pfkeyv2.h> | |
22 | #include <linux/percpu.h> | |
23 | #include <linux/smp.h> | |
24 | #include <linux/list.h> | |
25 | #include <linux/vmalloc.h> | |
26 | #include <linux/rtnetlink.h> | |
27 | #include <net/ip.h> | |
28 | #include <net/xfrm.h> | |
29 | #include <net/icmp.h> | |
30 | #include <net/ipcomp.h> | |
31 | ||
32 | struct ipcomp_tfms { | |
33 | struct list_head list; | |
34 | struct crypto_tfm **tfms; | |
35 | int users; | |
36 | }; | |
37 | ||
38 | static DECLARE_MUTEX(ipcomp_resource_sem); | |
39 | static void **ipcomp_scratches; | |
40 | static int ipcomp_scratch_users; | |
41 | static LIST_HEAD(ipcomp_tfms_list); | |
42 | ||
43 | static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb) | |
44 | { | |
45 | int err, plen, dlen; | |
46 | struct iphdr *iph; | |
47 | struct ipcomp_data *ipcd = x->data; | |
48 | u8 *start, *scratch; | |
49 | struct crypto_tfm *tfm; | |
50 | int cpu; | |
51 | ||
52 | plen = skb->len; | |
53 | dlen = IPCOMP_SCRATCH_SIZE; | |
54 | start = skb->data; | |
55 | ||
56 | cpu = get_cpu(); | |
57 | scratch = *per_cpu_ptr(ipcomp_scratches, cpu); | |
58 | tfm = *per_cpu_ptr(ipcd->tfms, cpu); | |
59 | ||
60 | err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen); | |
61 | if (err) | |
62 | goto out; | |
63 | ||
64 | if (dlen < (plen + sizeof(struct ip_comp_hdr))) { | |
65 | err = -EINVAL; | |
66 | goto out; | |
67 | } | |
68 | ||
69 | err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC); | |
70 | if (err) | |
71 | goto out; | |
72 | ||
73 | skb_put(skb, dlen - plen); | |
74 | memcpy(skb->data, scratch, dlen); | |
75 | iph = skb->nh.iph; | |
76 | iph->tot_len = htons(dlen + iph->ihl * 4); | |
77 | out: | |
78 | put_cpu(); | |
79 | return err; | |
80 | } | |
81 | ||
82 | static int ipcomp_input(struct xfrm_state *x, | |
83 | struct xfrm_decap_state *decap, struct sk_buff *skb) | |
84 | { | |
85 | u8 nexthdr; | |
86 | int err = 0; | |
87 | struct iphdr *iph; | |
88 | union { | |
89 | struct iphdr iph; | |
90 | char buf[60]; | |
91 | } tmp_iph; | |
92 | ||
93 | ||
94 | if ((skb_is_nonlinear(skb) || skb_cloned(skb)) && | |
95 | skb_linearize(skb, GFP_ATOMIC) != 0) { | |
96 | err = -ENOMEM; | |
97 | goto out; | |
98 | } | |
99 | ||
100 | skb->ip_summed = CHECKSUM_NONE; | |
101 | ||
102 | /* Remove ipcomp header and decompress original payload */ | |
103 | iph = skb->nh.iph; | |
104 | memcpy(&tmp_iph, iph, iph->ihl * 4); | |
105 | nexthdr = *(u8 *)skb->data; | |
106 | skb_pull(skb, sizeof(struct ip_comp_hdr)); | |
107 | skb->nh.raw += sizeof(struct ip_comp_hdr); | |
108 | memcpy(skb->nh.raw, &tmp_iph, tmp_iph.iph.ihl * 4); | |
109 | iph = skb->nh.iph; | |
110 | iph->tot_len = htons(ntohs(iph->tot_len) - sizeof(struct ip_comp_hdr)); | |
111 | iph->protocol = nexthdr; | |
112 | skb->h.raw = skb->data; | |
113 | err = ipcomp_decompress(x, skb); | |
114 | ||
115 | out: | |
116 | return err; | |
117 | } | |
118 | ||
119 | static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb) | |
120 | { | |
121 | int err, plen, dlen, ihlen; | |
122 | struct iphdr *iph = skb->nh.iph; | |
123 | struct ipcomp_data *ipcd = x->data; | |
124 | u8 *start, *scratch; | |
125 | struct crypto_tfm *tfm; | |
126 | int cpu; | |
127 | ||
128 | ihlen = iph->ihl * 4; | |
129 | plen = skb->len - ihlen; | |
130 | dlen = IPCOMP_SCRATCH_SIZE; | |
131 | start = skb->data + ihlen; | |
132 | ||
133 | cpu = get_cpu(); | |
134 | scratch = *per_cpu_ptr(ipcomp_scratches, cpu); | |
135 | tfm = *per_cpu_ptr(ipcd->tfms, cpu); | |
136 | ||
137 | err = crypto_comp_compress(tfm, start, plen, scratch, &dlen); | |
138 | if (err) | |
139 | goto out; | |
140 | ||
141 | if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) { | |
142 | err = -EMSGSIZE; | |
143 | goto out; | |
144 | } | |
145 | ||
146 | memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen); | |
147 | put_cpu(); | |
148 | ||
149 | pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr)); | |
150 | return 0; | |
151 | ||
152 | out: | |
153 | put_cpu(); | |
154 | return err; | |
155 | } | |
156 | ||
157 | static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb) | |
158 | { | |
159 | int err; | |
160 | struct iphdr *iph; | |
161 | struct ip_comp_hdr *ipch; | |
162 | struct ipcomp_data *ipcd = x->data; | |
163 | int hdr_len = 0; | |
164 | ||
165 | iph = skb->nh.iph; | |
166 | iph->tot_len = htons(skb->len); | |
167 | hdr_len = iph->ihl * 4; | |
168 | if ((skb->len - hdr_len) < ipcd->threshold) { | |
169 | /* Don't bother compressing */ | |
170 | goto out_ok; | |
171 | } | |
172 | ||
173 | if ((skb_is_nonlinear(skb) || skb_cloned(skb)) && | |
174 | skb_linearize(skb, GFP_ATOMIC) != 0) { | |
175 | goto out_ok; | |
176 | } | |
177 | ||
178 | err = ipcomp_compress(x, skb); | |
179 | iph = skb->nh.iph; | |
180 | ||
181 | if (err) { | |
182 | goto out_ok; | |
183 | } | |
184 | ||
185 | /* Install ipcomp header, convert into ipcomp datagram. */ | |
186 | iph->tot_len = htons(skb->len); | |
187 | ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4); | |
188 | ipch->nexthdr = iph->protocol; | |
189 | ipch->flags = 0; | |
190 | ipch->cpi = htons((u16 )ntohl(x->id.spi)); | |
191 | iph->protocol = IPPROTO_COMP; | |
192 | ip_send_check(iph); | |
193 | return 0; | |
194 | ||
195 | out_ok: | |
196 | if (x->props.mode) | |
197 | ip_send_check(iph); | |
198 | return 0; | |
199 | } | |
200 | ||
201 | static void ipcomp4_err(struct sk_buff *skb, u32 info) | |
202 | { | |
203 | u32 spi; | |
204 | struct iphdr *iph = (struct iphdr *)skb->data; | |
205 | struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2)); | |
206 | struct xfrm_state *x; | |
207 | ||
208 | if (skb->h.icmph->type != ICMP_DEST_UNREACH || | |
209 | skb->h.icmph->code != ICMP_FRAG_NEEDED) | |
210 | return; | |
211 | ||
212 | spi = ntohl(ntohs(ipch->cpi)); | |
213 | x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, | |
214 | spi, IPPROTO_COMP, AF_INET); | |
215 | if (!x) | |
216 | return; | |
64ce2073 PM |
217 | NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n", |
218 | spi, NIPQUAD(iph->daddr)); | |
1da177e4 LT |
219 | xfrm_state_put(x); |
220 | } | |
221 | ||
222 | /* We always hold one tunnel user reference to indicate a tunnel */ | |
223 | static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x) | |
224 | { | |
225 | struct xfrm_state *t; | |
226 | ||
227 | t = xfrm_state_alloc(); | |
228 | if (t == NULL) | |
229 | goto out; | |
230 | ||
231 | t->id.proto = IPPROTO_IPIP; | |
232 | t->id.spi = x->props.saddr.a4; | |
233 | t->id.daddr.a4 = x->id.daddr.a4; | |
234 | memcpy(&t->sel, &x->sel, sizeof(t->sel)); | |
235 | t->props.family = AF_INET; | |
236 | t->props.mode = 1; | |
237 | t->props.saddr.a4 = x->props.saddr.a4; | |
238 | t->props.flags = x->props.flags; | |
72cb6962 HX |
239 | |
240 | if (xfrm_init_state(t)) | |
1da177e4 LT |
241 | goto error; |
242 | ||
1da177e4 LT |
243 | atomic_set(&t->tunnel_users, 1); |
244 | out: | |
245 | return t; | |
246 | ||
247 | error: | |
248 | t->km.state = XFRM_STATE_DEAD; | |
249 | xfrm_state_put(t); | |
250 | t = NULL; | |
251 | goto out; | |
252 | } | |
253 | ||
254 | /* | |
255 | * Must be protected by xfrm_cfg_sem. State and tunnel user references are | |
256 | * always incremented on success. | |
257 | */ | |
258 | static int ipcomp_tunnel_attach(struct xfrm_state *x) | |
259 | { | |
260 | int err = 0; | |
261 | struct xfrm_state *t; | |
262 | ||
263 | t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4, | |
264 | x->props.saddr.a4, IPPROTO_IPIP, AF_INET); | |
265 | if (!t) { | |
266 | t = ipcomp_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 | out: | |
277 | return err; | |
278 | } | |
279 | ||
280 | static void ipcomp_free_scratches(void) | |
281 | { | |
282 | int i; | |
283 | void **scratches; | |
284 | ||
285 | if (--ipcomp_scratch_users) | |
286 | return; | |
287 | ||
288 | scratches = ipcomp_scratches; | |
289 | if (!scratches) | |
290 | return; | |
291 | ||
292 | for_each_cpu(i) { | |
293 | void *scratch = *per_cpu_ptr(scratches, i); | |
294 | if (scratch) | |
295 | vfree(scratch); | |
296 | } | |
297 | ||
298 | free_percpu(scratches); | |
299 | } | |
300 | ||
301 | static void **ipcomp_alloc_scratches(void) | |
302 | { | |
303 | int i; | |
304 | void **scratches; | |
305 | ||
306 | if (ipcomp_scratch_users++) | |
307 | return ipcomp_scratches; | |
308 | ||
309 | scratches = alloc_percpu(void *); | |
310 | if (!scratches) | |
311 | return NULL; | |
312 | ||
313 | ipcomp_scratches = scratches; | |
314 | ||
315 | for_each_cpu(i) { | |
316 | void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE); | |
317 | if (!scratch) | |
318 | return NULL; | |
319 | *per_cpu_ptr(scratches, i) = scratch; | |
320 | } | |
321 | ||
322 | return scratches; | |
323 | } | |
324 | ||
325 | static void ipcomp_free_tfms(struct crypto_tfm **tfms) | |
326 | { | |
327 | struct ipcomp_tfms *pos; | |
328 | int cpu; | |
329 | ||
330 | list_for_each_entry(pos, &ipcomp_tfms_list, list) { | |
331 | if (pos->tfms == tfms) | |
332 | break; | |
333 | } | |
334 | ||
335 | BUG_TRAP(pos); | |
336 | ||
337 | if (--pos->users) | |
338 | return; | |
339 | ||
340 | list_del(&pos->list); | |
341 | kfree(pos); | |
342 | ||
343 | if (!tfms) | |
344 | return; | |
345 | ||
346 | for_each_cpu(cpu) { | |
347 | struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu); | |
573dbd95 | 348 | crypto_free_tfm(tfm); |
1da177e4 LT |
349 | } |
350 | free_percpu(tfms); | |
351 | } | |
352 | ||
353 | static struct crypto_tfm **ipcomp_alloc_tfms(const char *alg_name) | |
354 | { | |
355 | struct ipcomp_tfms *pos; | |
356 | struct crypto_tfm **tfms; | |
357 | int cpu; | |
358 | ||
359 | /* This can be any valid CPU ID so we don't need locking. */ | |
6fc8b9e7 | 360 | cpu = raw_smp_processor_id(); |
1da177e4 LT |
361 | |
362 | list_for_each_entry(pos, &ipcomp_tfms_list, list) { | |
363 | struct crypto_tfm *tfm; | |
364 | ||
365 | tfms = pos->tfms; | |
366 | tfm = *per_cpu_ptr(tfms, cpu); | |
367 | ||
368 | if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) { | |
369 | pos->users++; | |
370 | return tfms; | |
371 | } | |
372 | } | |
373 | ||
374 | pos = kmalloc(sizeof(*pos), GFP_KERNEL); | |
375 | if (!pos) | |
376 | return NULL; | |
377 | ||
378 | pos->users = 1; | |
379 | INIT_LIST_HEAD(&pos->list); | |
380 | list_add(&pos->list, &ipcomp_tfms_list); | |
381 | ||
382 | pos->tfms = tfms = alloc_percpu(struct crypto_tfm *); | |
383 | if (!tfms) | |
384 | goto error; | |
385 | ||
386 | for_each_cpu(cpu) { | |
387 | struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0); | |
388 | if (!tfm) | |
389 | goto error; | |
390 | *per_cpu_ptr(tfms, cpu) = tfm; | |
391 | } | |
392 | ||
393 | return tfms; | |
394 | ||
395 | error: | |
396 | ipcomp_free_tfms(tfms); | |
397 | return NULL; | |
398 | } | |
399 | ||
400 | static void ipcomp_free_data(struct ipcomp_data *ipcd) | |
401 | { | |
402 | if (ipcd->tfms) | |
403 | ipcomp_free_tfms(ipcd->tfms); | |
404 | ipcomp_free_scratches(); | |
405 | } | |
406 | ||
407 | static void ipcomp_destroy(struct xfrm_state *x) | |
408 | { | |
409 | struct ipcomp_data *ipcd = x->data; | |
410 | if (!ipcd) | |
411 | return; | |
412 | xfrm_state_delete_tunnel(x); | |
413 | down(&ipcomp_resource_sem); | |
414 | ipcomp_free_data(ipcd); | |
415 | up(&ipcomp_resource_sem); | |
416 | kfree(ipcd); | |
417 | } | |
418 | ||
72cb6962 | 419 | static int ipcomp_init_state(struct xfrm_state *x) |
1da177e4 LT |
420 | { |
421 | int err; | |
422 | struct ipcomp_data *ipcd; | |
423 | struct xfrm_algo_desc *calg_desc; | |
424 | ||
425 | err = -EINVAL; | |
426 | if (!x->calg) | |
427 | goto out; | |
428 | ||
429 | if (x->encap) | |
430 | goto out; | |
431 | ||
432 | err = -ENOMEM; | |
433 | ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL); | |
434 | if (!ipcd) | |
435 | goto out; | |
436 | ||
437 | memset(ipcd, 0, sizeof(*ipcd)); | |
438 | x->props.header_len = 0; | |
439 | if (x->props.mode) | |
440 | x->props.header_len += sizeof(struct iphdr); | |
441 | ||
442 | down(&ipcomp_resource_sem); | |
443 | if (!ipcomp_alloc_scratches()) | |
444 | goto error; | |
445 | ||
446 | ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name); | |
447 | if (!ipcd->tfms) | |
448 | goto error; | |
449 | up(&ipcomp_resource_sem); | |
450 | ||
451 | if (x->props.mode) { | |
452 | err = ipcomp_tunnel_attach(x); | |
453 | if (err) | |
454 | goto error_tunnel; | |
455 | } | |
456 | ||
457 | calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0); | |
458 | BUG_ON(!calg_desc); | |
459 | ipcd->threshold = calg_desc->uinfo.comp.threshold; | |
460 | x->data = ipcd; | |
461 | err = 0; | |
462 | out: | |
463 | return err; | |
464 | ||
465 | error_tunnel: | |
466 | down(&ipcomp_resource_sem); | |
467 | error: | |
468 | ipcomp_free_data(ipcd); | |
469 | up(&ipcomp_resource_sem); | |
470 | kfree(ipcd); | |
471 | goto out; | |
472 | } | |
473 | ||
474 | static struct xfrm_type ipcomp_type = { | |
475 | .description = "IPCOMP4", | |
476 | .owner = THIS_MODULE, | |
477 | .proto = IPPROTO_COMP, | |
478 | .init_state = ipcomp_init_state, | |
479 | .destructor = ipcomp_destroy, | |
480 | .input = ipcomp_input, | |
481 | .output = ipcomp_output | |
482 | }; | |
483 | ||
484 | static struct net_protocol ipcomp4_protocol = { | |
485 | .handler = xfrm4_rcv, | |
486 | .err_handler = ipcomp4_err, | |
487 | .no_policy = 1, | |
488 | }; | |
489 | ||
490 | static int __init ipcomp4_init(void) | |
491 | { | |
492 | if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) { | |
493 | printk(KERN_INFO "ipcomp init: can't add xfrm type\n"); | |
494 | return -EAGAIN; | |
495 | } | |
496 | if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) { | |
497 | printk(KERN_INFO "ipcomp init: can't add protocol\n"); | |
498 | xfrm_unregister_type(&ipcomp_type, AF_INET); | |
499 | return -EAGAIN; | |
500 | } | |
501 | return 0; | |
502 | } | |
503 | ||
504 | static void __exit ipcomp4_fini(void) | |
505 | { | |
506 | if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) | |
507 | printk(KERN_INFO "ip ipcomp close: can't remove protocol\n"); | |
508 | if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0) | |
509 | printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n"); | |
510 | } | |
511 | ||
512 | module_init(ipcomp4_init); | |
513 | module_exit(ipcomp4_fini); | |
514 | ||
515 | MODULE_LICENSE("GPL"); | |
516 | MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173"); | |
517 | MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); | |
518 |