Linux 2.6.19-rc6
[cris-mirror.git] / net / ipv4 / ipcomp.c
blob3839b706142e3816f73bbc9a6ff361a9f8467d44
1 /*
2 * IP Payload Compression Protocol (IPComp) - RFC3173.
4 * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
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.
11 * Todo:
12 * - Tunable compression parameters.
13 * - Compression stats.
14 * - Adaptive compression.
16 #include <linux/module.h>
17 #include <asm/scatterlist.h>
18 #include <asm/semaphore.h>
19 #include <linux/crypto.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>
33 struct ipcomp_tfms {
34 struct list_head list;
35 struct crypto_comp **tfms;
36 int users;
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);
44 static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
46 int err, plen, dlen;
47 struct ipcomp_data *ipcd = x->data;
48 u8 *start, *scratch;
49 struct crypto_comp *tfm;
50 int cpu;
52 plen = skb->len;
53 dlen = IPCOMP_SCRATCH_SIZE;
54 start = skb->data;
56 cpu = get_cpu();
57 scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
58 tfm = *per_cpu_ptr(ipcd->tfms, cpu);
60 err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
61 if (err)
62 goto out;
64 if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
65 err = -EINVAL;
66 goto out;
69 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
70 if (err)
71 goto out;
73 skb->truesize += dlen - plen;
74 __skb_put(skb, dlen - plen);
75 memcpy(skb->data, scratch, dlen);
76 out:
77 put_cpu();
78 return err;
81 static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
83 int err = -ENOMEM;
84 struct iphdr *iph;
85 struct ip_comp_hdr *ipch;
87 if (skb_linearize_cow(skb))
88 goto out;
90 skb->ip_summed = CHECKSUM_NONE;
92 /* Remove ipcomp header and decompress original payload */
93 iph = skb->nh.iph;
94 ipch = (void *)skb->data;
95 iph->protocol = ipch->nexthdr;
96 skb->h.raw = skb->nh.raw + sizeof(*ipch);
97 __skb_pull(skb, sizeof(*ipch));
98 err = ipcomp_decompress(x, skb);
100 out:
101 return err;
104 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
106 int err, plen, dlen, ihlen;
107 struct iphdr *iph = skb->nh.iph;
108 struct ipcomp_data *ipcd = x->data;
109 u8 *start, *scratch;
110 struct crypto_comp *tfm;
111 int cpu;
113 ihlen = iph->ihl * 4;
114 plen = skb->len - ihlen;
115 dlen = IPCOMP_SCRATCH_SIZE;
116 start = skb->data + ihlen;
118 cpu = get_cpu();
119 scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
120 tfm = *per_cpu_ptr(ipcd->tfms, cpu);
122 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
123 if (err)
124 goto out;
126 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
127 err = -EMSGSIZE;
128 goto out;
131 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
132 put_cpu();
134 pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr));
135 return 0;
137 out:
138 put_cpu();
139 return err;
142 static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
144 int err;
145 struct iphdr *iph;
146 struct ip_comp_hdr *ipch;
147 struct ipcomp_data *ipcd = x->data;
148 int hdr_len = 0;
150 iph = skb->nh.iph;
151 iph->tot_len = htons(skb->len);
152 hdr_len = iph->ihl * 4;
153 if ((skb->len - hdr_len) < ipcd->threshold) {
154 /* Don't bother compressing */
155 goto out_ok;
158 if (skb_linearize_cow(skb))
159 goto out_ok;
161 err = ipcomp_compress(x, skb);
162 iph = skb->nh.iph;
164 if (err) {
165 goto out_ok;
168 /* Install ipcomp header, convert into ipcomp datagram. */
169 iph->tot_len = htons(skb->len);
170 ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4);
171 ipch->nexthdr = iph->protocol;
172 ipch->flags = 0;
173 ipch->cpi = htons((u16 )ntohl(x->id.spi));
174 iph->protocol = IPPROTO_COMP;
175 ip_send_check(iph);
176 return 0;
178 out_ok:
179 if (x->props.mode == XFRM_MODE_TUNNEL)
180 ip_send_check(iph);
181 return 0;
184 static void ipcomp4_err(struct sk_buff *skb, u32 info)
186 __be32 spi;
187 struct iphdr *iph = (struct iphdr *)skb->data;
188 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
189 struct xfrm_state *x;
191 if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
192 skb->h.icmph->code != ICMP_FRAG_NEEDED)
193 return;
195 spi = htonl(ntohs(ipch->cpi));
196 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
197 spi, IPPROTO_COMP, AF_INET);
198 if (!x)
199 return;
200 NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n",
201 spi, NIPQUAD(iph->daddr));
202 xfrm_state_put(x);
205 /* We always hold one tunnel user reference to indicate a tunnel */
206 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
208 struct xfrm_state *t;
209 u8 mode = XFRM_MODE_TUNNEL;
211 t = xfrm_state_alloc();
212 if (t == NULL)
213 goto out;
215 t->id.proto = IPPROTO_IPIP;
216 t->id.spi = x->props.saddr.a4;
217 t->id.daddr.a4 = x->id.daddr.a4;
218 memcpy(&t->sel, &x->sel, sizeof(t->sel));
219 t->props.family = AF_INET;
220 if (x->props.mode == XFRM_MODE_BEET)
221 mode = x->props.mode;
222 t->props.mode = mode;
223 t->props.saddr.a4 = x->props.saddr.a4;
224 t->props.flags = x->props.flags;
226 if (xfrm_init_state(t))
227 goto error;
229 atomic_set(&t->tunnel_users, 1);
230 out:
231 return t;
233 error:
234 t->km.state = XFRM_STATE_DEAD;
235 xfrm_state_put(t);
236 t = NULL;
237 goto out;
241 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are
242 * always incremented on success.
244 static int ipcomp_tunnel_attach(struct xfrm_state *x)
246 int err = 0;
247 struct xfrm_state *t;
249 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
250 x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
251 if (!t) {
252 t = ipcomp_tunnel_create(x);
253 if (!t) {
254 err = -EINVAL;
255 goto out;
257 xfrm_state_insert(t);
258 xfrm_state_hold(t);
260 x->tunnel = t;
261 atomic_inc(&t->tunnel_users);
262 out:
263 return err;
266 static void ipcomp_free_scratches(void)
268 int i;
269 void **scratches;
271 if (--ipcomp_scratch_users)
272 return;
274 scratches = ipcomp_scratches;
275 if (!scratches)
276 return;
278 for_each_possible_cpu(i)
279 vfree(*per_cpu_ptr(scratches, i));
281 free_percpu(scratches);
284 static void **ipcomp_alloc_scratches(void)
286 int i;
287 void **scratches;
289 if (ipcomp_scratch_users++)
290 return ipcomp_scratches;
292 scratches = alloc_percpu(void *);
293 if (!scratches)
294 return NULL;
296 ipcomp_scratches = scratches;
298 for_each_possible_cpu(i) {
299 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
300 if (!scratch)
301 return NULL;
302 *per_cpu_ptr(scratches, i) = scratch;
305 return scratches;
308 static void ipcomp_free_tfms(struct crypto_comp **tfms)
310 struct ipcomp_tfms *pos;
311 int cpu;
313 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
314 if (pos->tfms == tfms)
315 break;
318 BUG_TRAP(pos);
320 if (--pos->users)
321 return;
323 list_del(&pos->list);
324 kfree(pos);
326 if (!tfms)
327 return;
329 for_each_possible_cpu(cpu) {
330 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
331 crypto_free_comp(tfm);
333 free_percpu(tfms);
336 static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name)
338 struct ipcomp_tfms *pos;
339 struct crypto_comp **tfms;
340 int cpu;
342 /* This can be any valid CPU ID so we don't need locking. */
343 cpu = raw_smp_processor_id();
345 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
346 struct crypto_comp *tfm;
348 tfms = pos->tfms;
349 tfm = *per_cpu_ptr(tfms, cpu);
351 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
352 pos->users++;
353 return tfms;
357 pos = kmalloc(sizeof(*pos), GFP_KERNEL);
358 if (!pos)
359 return NULL;
361 pos->users = 1;
362 INIT_LIST_HEAD(&pos->list);
363 list_add(&pos->list, &ipcomp_tfms_list);
365 pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
366 if (!tfms)
367 goto error;
369 for_each_possible_cpu(cpu) {
370 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
371 CRYPTO_ALG_ASYNC);
372 if (!tfm)
373 goto error;
374 *per_cpu_ptr(tfms, cpu) = tfm;
377 return tfms;
379 error:
380 ipcomp_free_tfms(tfms);
381 return NULL;
384 static void ipcomp_free_data(struct ipcomp_data *ipcd)
386 if (ipcd->tfms)
387 ipcomp_free_tfms(ipcd->tfms);
388 ipcomp_free_scratches();
391 static void ipcomp_destroy(struct xfrm_state *x)
393 struct ipcomp_data *ipcd = x->data;
394 if (!ipcd)
395 return;
396 xfrm_state_delete_tunnel(x);
397 mutex_lock(&ipcomp_resource_mutex);
398 ipcomp_free_data(ipcd);
399 mutex_unlock(&ipcomp_resource_mutex);
400 kfree(ipcd);
403 static int ipcomp_init_state(struct xfrm_state *x)
405 int err;
406 struct ipcomp_data *ipcd;
407 struct xfrm_algo_desc *calg_desc;
409 err = -EINVAL;
410 if (!x->calg)
411 goto out;
413 if (x->encap)
414 goto out;
416 err = -ENOMEM;
417 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
418 if (!ipcd)
419 goto out;
421 x->props.header_len = 0;
422 if (x->props.mode == XFRM_MODE_TUNNEL)
423 x->props.header_len += sizeof(struct iphdr);
425 mutex_lock(&ipcomp_resource_mutex);
426 if (!ipcomp_alloc_scratches())
427 goto error;
429 ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
430 if (!ipcd->tfms)
431 goto error;
432 mutex_unlock(&ipcomp_resource_mutex);
434 if (x->props.mode == XFRM_MODE_TUNNEL) {
435 err = ipcomp_tunnel_attach(x);
436 if (err)
437 goto error_tunnel;
440 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
441 BUG_ON(!calg_desc);
442 ipcd->threshold = calg_desc->uinfo.comp.threshold;
443 x->data = ipcd;
444 err = 0;
445 out:
446 return err;
448 error_tunnel:
449 mutex_lock(&ipcomp_resource_mutex);
450 error:
451 ipcomp_free_data(ipcd);
452 mutex_unlock(&ipcomp_resource_mutex);
453 kfree(ipcd);
454 goto out;
457 static struct xfrm_type ipcomp_type = {
458 .description = "IPCOMP4",
459 .owner = THIS_MODULE,
460 .proto = IPPROTO_COMP,
461 .init_state = ipcomp_init_state,
462 .destructor = ipcomp_destroy,
463 .input = ipcomp_input,
464 .output = ipcomp_output
467 static struct net_protocol ipcomp4_protocol = {
468 .handler = xfrm4_rcv,
469 .err_handler = ipcomp4_err,
470 .no_policy = 1,
473 static int __init ipcomp4_init(void)
475 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
476 printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
477 return -EAGAIN;
479 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
480 printk(KERN_INFO "ipcomp init: can't add protocol\n");
481 xfrm_unregister_type(&ipcomp_type, AF_INET);
482 return -EAGAIN;
484 return 0;
487 static void __exit ipcomp4_fini(void)
489 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
490 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
491 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
492 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
495 module_init(ipcomp4_init);
496 module_exit(ipcomp4_fini);
498 MODULE_LICENSE("GPL");
499 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
500 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");