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)
12 * - Tunable compression parameters.
13 * - Compression stats.
14 * - Adaptive compression.
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 <linux/mutex.h>
31 #include <net/ipcomp.h>
32 #include <net/protocol.h>
35 struct list_head list;
36 struct crypto_tfm **tfms;
40 static DEFINE_MUTEX(ipcomp_resource_mutex);
41 static void **ipcomp_scratches;
42 static int ipcomp_scratch_users;
43 static LIST_HEAD(ipcomp_tfms_list);
45 static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
48 struct ipcomp_data *ipcd = x->data;
50 struct crypto_tfm *tfm;
54 dlen = IPCOMP_SCRATCH_SIZE;
58 scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
59 tfm = *per_cpu_ptr(ipcd->tfms, cpu);
61 err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
65 if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
70 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
74 skb_put(skb, dlen - plen);
75 memcpy(skb->data, scratch, dlen);
81 static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
85 struct ip_comp_hdr *ipch;
87 if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
88 skb_linearize(skb, GFP_ATOMIC) != 0) {
93 skb->ip_summed = CHECKSUM_NONE;
95 /* Remove ipcomp header and decompress original payload */
97 ipch = (void *)skb->data;
98 iph->protocol = ipch->nexthdr;
99 skb->h.raw = skb->nh.raw + sizeof(*ipch);
100 __skb_pull(skb, sizeof(*ipch));
101 err = ipcomp_decompress(x, skb);
107 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
109 int err, plen, dlen, ihlen;
110 struct iphdr *iph = skb->nh.iph;
111 struct ipcomp_data *ipcd = x->data;
113 struct crypto_tfm *tfm;
116 ihlen = iph->ihl * 4;
117 plen = skb->len - ihlen;
118 dlen = IPCOMP_SCRATCH_SIZE;
119 start = skb->data + ihlen;
122 scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
123 tfm = *per_cpu_ptr(ipcd->tfms, cpu);
125 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
129 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
134 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
137 pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr));
145 static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
149 struct ip_comp_hdr *ipch;
150 struct ipcomp_data *ipcd = x->data;
154 iph->tot_len = htons(skb->len);
155 hdr_len = iph->ihl * 4;
156 if ((skb->len - hdr_len) < ipcd->threshold) {
157 /* Don't bother compressing */
161 if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
162 skb_linearize(skb, GFP_ATOMIC) != 0) {
166 err = ipcomp_compress(x, skb);
173 /* Install ipcomp header, convert into ipcomp datagram. */
174 iph->tot_len = htons(skb->len);
175 ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4);
176 ipch->nexthdr = iph->protocol;
178 ipch->cpi = htons((u16 )ntohl(x->id.spi));
179 iph->protocol = IPPROTO_COMP;
189 static void ipcomp4_err(struct sk_buff *skb, u32 info)
192 struct iphdr *iph = (struct iphdr *)skb->data;
193 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
194 struct xfrm_state *x;
196 if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
197 skb->h.icmph->code != ICMP_FRAG_NEEDED)
200 spi = htonl(ntohs(ipch->cpi));
201 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
202 spi, IPPROTO_COMP, AF_INET);
205 NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n",
206 spi, NIPQUAD(iph->daddr));
210 /* We always hold one tunnel user reference to indicate a tunnel */
211 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
213 struct xfrm_state *t;
215 t = xfrm_state_alloc();
219 t->id.proto = IPPROTO_IPIP;
220 t->id.spi = x->props.saddr.a4;
221 t->id.daddr.a4 = x->id.daddr.a4;
222 memcpy(&t->sel, &x->sel, sizeof(t->sel));
223 t->props.family = AF_INET;
225 t->props.saddr.a4 = x->props.saddr.a4;
226 t->props.flags = x->props.flags;
228 if (xfrm_init_state(t))
231 atomic_set(&t->tunnel_users, 1);
236 t->km.state = XFRM_STATE_DEAD;
243 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are
244 * always incremented on success.
246 static int ipcomp_tunnel_attach(struct xfrm_state *x)
249 struct xfrm_state *t;
251 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
252 x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
254 t = ipcomp_tunnel_create(x);
259 xfrm_state_insert(t);
263 atomic_inc(&t->tunnel_users);
268 static void ipcomp_free_scratches(void)
273 if (--ipcomp_scratch_users)
276 scratches = ipcomp_scratches;
280 for_each_possible_cpu(i)
281 vfree(*per_cpu_ptr(scratches, i));
283 free_percpu(scratches);
286 static void **ipcomp_alloc_scratches(void)
291 if (ipcomp_scratch_users++)
292 return ipcomp_scratches;
294 scratches = alloc_percpu(void *);
298 ipcomp_scratches = scratches;
300 for_each_possible_cpu(i) {
301 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
304 *per_cpu_ptr(scratches, i) = scratch;
310 static void ipcomp_free_tfms(struct crypto_tfm **tfms)
312 struct ipcomp_tfms *pos;
315 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
316 if (pos->tfms == tfms)
325 list_del(&pos->list);
331 for_each_possible_cpu(cpu) {
332 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu);
333 crypto_free_tfm(tfm);
338 static struct crypto_tfm **ipcomp_alloc_tfms(const char *alg_name)
340 struct ipcomp_tfms *pos;
341 struct crypto_tfm **tfms;
344 /* This can be any valid CPU ID so we don't need locking. */
345 cpu = raw_smp_processor_id();
347 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
348 struct crypto_tfm *tfm;
351 tfm = *per_cpu_ptr(tfms, cpu);
353 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) {
359 pos = kmalloc(sizeof(*pos), GFP_KERNEL);
364 INIT_LIST_HEAD(&pos->list);
365 list_add(&pos->list, &ipcomp_tfms_list);
367 pos->tfms = tfms = alloc_percpu(struct crypto_tfm *);
371 for_each_possible_cpu(cpu) {
372 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0);
375 *per_cpu_ptr(tfms, cpu) = tfm;
381 ipcomp_free_tfms(tfms);
385 static void ipcomp_free_data(struct ipcomp_data *ipcd)
388 ipcomp_free_tfms(ipcd->tfms);
389 ipcomp_free_scratches();
392 static void ipcomp_destroy(struct xfrm_state *x)
394 struct ipcomp_data *ipcd = x->data;
397 xfrm_state_delete_tunnel(x);
398 mutex_lock(&ipcomp_resource_mutex);
399 ipcomp_free_data(ipcd);
400 mutex_unlock(&ipcomp_resource_mutex);
404 static int ipcomp_init_state(struct xfrm_state *x)
407 struct ipcomp_data *ipcd;
408 struct xfrm_algo_desc *calg_desc;
418 ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL);
422 memset(ipcd, 0, sizeof(*ipcd));
423 x->props.header_len = 0;
425 x->props.header_len += sizeof(struct iphdr);
427 mutex_lock(&ipcomp_resource_mutex);
428 if (!ipcomp_alloc_scratches())
431 ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
434 mutex_unlock(&ipcomp_resource_mutex);
437 err = ipcomp_tunnel_attach(x);
442 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
444 ipcd->threshold = calg_desc->uinfo.comp.threshold;
451 mutex_lock(&ipcomp_resource_mutex);
453 ipcomp_free_data(ipcd);
454 mutex_unlock(&ipcomp_resource_mutex);
459 static struct xfrm_type ipcomp_type = {
460 .description = "IPCOMP4",
461 .owner = THIS_MODULE,
462 .proto = IPPROTO_COMP,
463 .init_state = ipcomp_init_state,
464 .destructor = ipcomp_destroy,
465 .input = ipcomp_input,
466 .output = ipcomp_output
469 static struct net_protocol ipcomp4_protocol = {
470 .handler = xfrm4_rcv,
471 .err_handler = ipcomp4_err,
475 static int __init ipcomp4_init(void)
477 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
478 printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
481 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
482 printk(KERN_INFO "ipcomp init: can't add protocol\n");
483 xfrm_unregister_type(&ipcomp_type, AF_INET);
489 static void __exit ipcomp4_fini(void)
491 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
492 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
493 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
494 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
497 module_init(ipcomp4_init);
498 module_exit(ipcomp4_fini);
500 MODULE_LICENSE("GPL");
501 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
502 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");