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/module.h>
17 #include <asm/semaphore.h>
18 #include <linux/crypto.h>
19 #include <linux/err.h>
20 #include <linux/pfkeyv2.h>
21 #include <linux/percpu.h>
22 #include <linux/smp.h>
23 #include <linux/list.h>
24 #include <linux/vmalloc.h>
25 #include <linux/rtnetlink.h>
26 #include <linux/mutex.h>
27 #include <net/ip.h>
28 #include <net/xfrm.h>
29 #include <net/icmp.h>
30 #include <net/ipcomp.h>
31 #include <net/protocol.h>
32
33 struct ipcomp_tfms {
34 struct list_head list;
35 struct crypto_comp **tfms;
36 int users;
37 };
38
39 static DEFINE_MUTEX(ipcomp_resource_mutex);
40 static void **ipcomp_scratches;
41 static int ipcomp_scratch_users;
42 static LIST_HEAD(ipcomp_tfms_list);
43
44 static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
45 {
46 struct ipcomp_data *ipcd = x->data;
47 const int plen = skb->len;
48 int dlen = IPCOMP_SCRATCH_SIZE;
49 const u8 *start = skb->data;
50 const int cpu = get_cpu();
51 u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
52 struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
53 int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
54
55 if (err)
56 goto out;
57
58 if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
59 err = -EINVAL;
60 goto out;
61 }
62
63 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
64 if (err)
65 goto out;
66
67 skb->truesize += dlen - plen;
68 __skb_put(skb, dlen - plen);
69 skb_copy_to_linear_data(skb, scratch, dlen);
70 out:
71 put_cpu();
72 return err;
73 }
74
75 static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
76 {
77 int nexthdr;
78 int err = -ENOMEM;
79 struct ip_comp_hdr *ipch;
80
81 if (skb_linearize_cow(skb))
82 goto out;
83
84 skb->ip_summed = CHECKSUM_NONE;
85
86 /* Remove ipcomp header and decompress original payload */
87 ipch = (void *)skb->data;
88 nexthdr = ipch->nexthdr;
89
90 skb->transport_header = skb->network_header + sizeof(*ipch);
91 __skb_pull(skb, sizeof(*ipch));
92 err = ipcomp_decompress(x, skb);
93 if (err)
94 goto out;
95
96 err = nexthdr;
97
98 out:
99 return err;
100 }
101
102 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
103 {
104 struct ipcomp_data *ipcd = x->data;
105 const int plen = skb->len;
106 int dlen = IPCOMP_SCRATCH_SIZE;
107 u8 *start = skb->data;
108 const int cpu = get_cpu();
109 u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
110 struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
111 int err;
112
113 local_bh_disable();
114 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
115 local_bh_enable();
116 if (err)
117 goto out;
118
119 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
120 err = -EMSGSIZE;
121 goto out;
122 }
123
124 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
125 put_cpu();
126
127 pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
128 return 0;
129
130 out:
131 put_cpu();
132 return err;
133 }
134
135 static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
136 {
137 int err;
138 struct ip_comp_hdr *ipch;
139 struct ipcomp_data *ipcd = x->data;
140
141 if (skb->len < ipcd->threshold) {
142 /* Don't bother compressing */
143 goto out_ok;
144 }
145
146 if (skb_linearize_cow(skb))
147 goto out_ok;
148
149 err = ipcomp_compress(x, skb);
150
151 if (err) {
152 goto out_ok;
153 }
154
155 /* Install ipcomp header, convert into ipcomp datagram. */
156 ipch = ip_comp_hdr(skb);
157 ipch->nexthdr = *skb_mac_header(skb);
158 ipch->flags = 0;
159 ipch->cpi = htons((u16 )ntohl(x->id.spi));
160 *skb_mac_header(skb) = IPPROTO_COMP;
161 out_ok:
162 skb_push(skb, -skb_network_offset(skb));
163 return 0;
164 }
165
166 static void ipcomp4_err(struct sk_buff *skb, u32 info)
167 {
168 __be32 spi;
169 struct iphdr *iph = (struct iphdr *)skb->data;
170 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
171 struct xfrm_state *x;
172
173 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
174 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
175 return;
176
177 spi = htonl(ntohs(ipch->cpi));
178 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
179 spi, IPPROTO_COMP, AF_INET);
180 if (!x)
181 return;
182 NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n",
183 spi, NIPQUAD(iph->daddr));
184 xfrm_state_put(x);
185 }
186
187 /* We always hold one tunnel user reference to indicate a tunnel */
188 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
189 {
190 struct xfrm_state *t;
191
192 t = xfrm_state_alloc();
193 if (t == NULL)
194 goto out;
195
196 t->id.proto = IPPROTO_IPIP;
197 t->id.spi = x->props.saddr.a4;
198 t->id.daddr.a4 = x->id.daddr.a4;
199 memcpy(&t->sel, &x->sel, sizeof(t->sel));
200 t->props.family = AF_INET;
201 t->props.mode = x->props.mode;
202 t->props.saddr.a4 = x->props.saddr.a4;
203 t->props.flags = x->props.flags;
204
205 if (xfrm_init_state(t))
206 goto error;
207
208 atomic_set(&t->tunnel_users, 1);
209 out:
210 return t;
211
212 error:
213 t->km.state = XFRM_STATE_DEAD;
214 xfrm_state_put(t);
215 t = NULL;
216 goto out;
217 }
218
219 /*
220 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are
221 * always incremented on success.
222 */
223 static int ipcomp_tunnel_attach(struct xfrm_state *x)
224 {
225 int err = 0;
226 struct xfrm_state *t;
227
228 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
229 x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
230 if (!t) {
231 t = ipcomp_tunnel_create(x);
232 if (!t) {
233 err = -EINVAL;
234 goto out;
235 }
236 xfrm_state_insert(t);
237 xfrm_state_hold(t);
238 }
239 x->tunnel = t;
240 atomic_inc(&t->tunnel_users);
241 out:
242 return err;
243 }
244
245 static void ipcomp_free_scratches(void)
246 {
247 int i;
248 void **scratches;
249
250 if (--ipcomp_scratch_users)
251 return;
252
253 scratches = ipcomp_scratches;
254 if (!scratches)
255 return;
256
257 for_each_possible_cpu(i)
258 vfree(*per_cpu_ptr(scratches, i));
259
260 free_percpu(scratches);
261 }
262
263 static void **ipcomp_alloc_scratches(void)
264 {
265 int i;
266 void **scratches;
267
268 if (ipcomp_scratch_users++)
269 return ipcomp_scratches;
270
271 scratches = alloc_percpu(void *);
272 if (!scratches)
273 return NULL;
274
275 ipcomp_scratches = scratches;
276
277 for_each_possible_cpu(i) {
278 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
279 if (!scratch)
280 return NULL;
281 *per_cpu_ptr(scratches, i) = scratch;
282 }
283
284 return scratches;
285 }
286
287 static void ipcomp_free_tfms(struct crypto_comp **tfms)
288 {
289 struct ipcomp_tfms *pos;
290 int cpu;
291
292 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
293 if (pos->tfms == tfms)
294 break;
295 }
296
297 BUG_TRAP(pos);
298
299 if (--pos->users)
300 return;
301
302 list_del(&pos->list);
303 kfree(pos);
304
305 if (!tfms)
306 return;
307
308 for_each_possible_cpu(cpu) {
309 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
310 crypto_free_comp(tfm);
311 }
312 free_percpu(tfms);
313 }
314
315 static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name)
316 {
317 struct ipcomp_tfms *pos;
318 struct crypto_comp **tfms;
319 int cpu;
320
321 /* This can be any valid CPU ID so we don't need locking. */
322 cpu = raw_smp_processor_id();
323
324 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
325 struct crypto_comp *tfm;
326
327 tfms = pos->tfms;
328 tfm = *per_cpu_ptr(tfms, cpu);
329
330 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
331 pos->users++;
332 return tfms;
333 }
334 }
335
336 pos = kmalloc(sizeof(*pos), GFP_KERNEL);
337 if (!pos)
338 return NULL;
339
340 pos->users = 1;
341 INIT_LIST_HEAD(&pos->list);
342 list_add(&pos->list, &ipcomp_tfms_list);
343
344 pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
345 if (!tfms)
346 goto error;
347
348 for_each_possible_cpu(cpu) {
349 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
350 CRYPTO_ALG_ASYNC);
351 if (IS_ERR(tfm))
352 goto error;
353 *per_cpu_ptr(tfms, cpu) = tfm;
354 }
355
356 return tfms;
357
358 error:
359 ipcomp_free_tfms(tfms);
360 return NULL;
361 }
362
363 static void ipcomp_free_data(struct ipcomp_data *ipcd)
364 {
365 if (ipcd->tfms)
366 ipcomp_free_tfms(ipcd->tfms);
367 ipcomp_free_scratches();
368 }
369
370 static void ipcomp_destroy(struct xfrm_state *x)
371 {
372 struct ipcomp_data *ipcd = x->data;
373 if (!ipcd)
374 return;
375 xfrm_state_delete_tunnel(x);
376 mutex_lock(&ipcomp_resource_mutex);
377 ipcomp_free_data(ipcd);
378 mutex_unlock(&ipcomp_resource_mutex);
379 kfree(ipcd);
380 }
381
382 static int ipcomp_init_state(struct xfrm_state *x)
383 {
384 int err;
385 struct ipcomp_data *ipcd;
386 struct xfrm_algo_desc *calg_desc;
387
388 err = -EINVAL;
389 if (!x->calg)
390 goto out;
391
392 if (x->encap)
393 goto out;
394
395 x->props.header_len = 0;
396 switch (x->props.mode) {
397 case XFRM_MODE_TRANSPORT:
398 break;
399 case XFRM_MODE_TUNNEL:
400 x->props.header_len += sizeof(struct iphdr);
401 break;
402 default:
403 goto out;
404 }
405
406 err = -ENOMEM;
407 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
408 if (!ipcd)
409 goto out;
410
411 mutex_lock(&ipcomp_resource_mutex);
412 if (!ipcomp_alloc_scratches())
413 goto error;
414
415 ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
416 if (!ipcd->tfms)
417 goto error;
418 mutex_unlock(&ipcomp_resource_mutex);
419
420 if (x->props.mode == XFRM_MODE_TUNNEL) {
421 err = ipcomp_tunnel_attach(x);
422 if (err)
423 goto error_tunnel;
424 }
425
426 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
427 BUG_ON(!calg_desc);
428 ipcd->threshold = calg_desc->uinfo.comp.threshold;
429 x->data = ipcd;
430 err = 0;
431 out:
432 return err;
433
434 error_tunnel:
435 mutex_lock(&ipcomp_resource_mutex);
436 error:
437 ipcomp_free_data(ipcd);
438 mutex_unlock(&ipcomp_resource_mutex);
439 kfree(ipcd);
440 goto out;
441 }
442
443 static const struct xfrm_type ipcomp_type = {
444 .description = "IPCOMP4",
445 .owner = THIS_MODULE,
446 .proto = IPPROTO_COMP,
447 .init_state = ipcomp_init_state,
448 .destructor = ipcomp_destroy,
449 .input = ipcomp_input,
450 .output = ipcomp_output
451 };
452
453 static struct net_protocol ipcomp4_protocol = {
454 .handler = xfrm4_rcv,
455 .err_handler = ipcomp4_err,
456 .no_policy = 1,
457 };
458
459 static int __init ipcomp4_init(void)
460 {
461 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
462 printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
463 return -EAGAIN;
464 }
465 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
466 printk(KERN_INFO "ipcomp init: can't add protocol\n");
467 xfrm_unregister_type(&ipcomp_type, AF_INET);
468 return -EAGAIN;
469 }
470 return 0;
471 }
472
473 static void __exit ipcomp4_fini(void)
474 {
475 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
476 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
477 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
478 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
479 }
480
481 module_init(ipcomp4_init);
482 module_exit(ipcomp4_fini);
483
484 MODULE_LICENSE("GPL");
485 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
486 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
487
488 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP);
489
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