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/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>
30 #include <net/ipcomp.h>
31 #include <net/protocol.h>
34 struct list_head list;
35 struct crypto_tfm **tfms;
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)
47 struct ipcomp_data *ipcd = x->data;
49 struct crypto_tfm *tfm;
53 dlen = IPCOMP_SCRATCH_SIZE;
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);
64 if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
69 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
73 skb_put(skb, dlen - plen);
74 memcpy(skb->data, scratch, dlen);
80 static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
84 struct ip_comp_hdr *ipch;
86 if (skb_linearize_cow(skb))
89 skb->ip_summed = CHECKSUM_NONE;
91 /* Remove ipcomp header and decompress original payload */
93 ipch = (void *)skb->data;
94 iph->protocol = ipch->nexthdr;
95 skb->h.raw = skb->nh.raw + sizeof(*ipch);
96 __skb_pull(skb, sizeof(*ipch));
97 err = ipcomp_decompress(x, skb);
103 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
105 int err, plen, dlen, ihlen;
106 struct iphdr *iph = skb->nh.iph;
107 struct ipcomp_data *ipcd = x->data;
109 struct crypto_tfm *tfm;
112 ihlen = iph->ihl * 4;
113 plen = skb->len - ihlen;
114 dlen = IPCOMP_SCRATCH_SIZE;
115 start = skb->data + ihlen;
118 scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
119 tfm = *per_cpu_ptr(ipcd->tfms, cpu);
121 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
125 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
130 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
133 pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr));
141 static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
145 struct ip_comp_hdr *ipch;
146 struct ipcomp_data *ipcd = x->data;
150 iph->tot_len = htons(skb->len);
151 hdr_len = iph->ihl * 4;
152 if ((skb->len - hdr_len) < ipcd->threshold) {
153 /* Don't bother compressing */
157 if (skb_linearize_cow(skb))
160 err = ipcomp_compress(x, skb);
167 /* Install ipcomp header, convert into ipcomp datagram. */
168 iph->tot_len = htons(skb->len);
169 ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4);
170 ipch->nexthdr = iph->protocol;
172 ipch->cpi = htons((u16 )ntohl(x->id.spi));
173 iph->protocol = IPPROTO_COMP;
183 static void ipcomp4_err(struct sk_buff *skb, u32 info)
186 struct iphdr *iph = (struct iphdr *)skb->data;
187 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
188 struct xfrm_state *x;
190 if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
191 skb->h.icmph->code != ICMP_FRAG_NEEDED)
194 spi = htonl(ntohs(ipch->cpi));
195 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
196 spi, IPPROTO_COMP, AF_INET);
199 NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n",
200 spi, NIPQUAD(iph->daddr));
204 /* We always hold one tunnel user reference to indicate a tunnel */
205 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
207 struct xfrm_state *t;
209 t = xfrm_state_alloc();
213 t->id.proto = IPPROTO_IPIP;
214 t->id.spi = x->props.saddr.a4;
215 t->id.daddr.a4 = x->id.daddr.a4;
216 memcpy(&t->sel, &x->sel, sizeof(t->sel));
217 t->props.family = AF_INET;
219 t->props.saddr.a4 = x->props.saddr.a4;
220 t->props.flags = x->props.flags;
222 if (xfrm_init_state(t))
225 atomic_set(&t->tunnel_users, 1);
230 t->km.state = XFRM_STATE_DEAD;
237 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are
238 * always incremented on success.
240 static int ipcomp_tunnel_attach(struct xfrm_state *x)
243 struct xfrm_state *t;
245 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
246 x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
248 t = ipcomp_tunnel_create(x);
253 xfrm_state_insert(t);
257 atomic_inc(&t->tunnel_users);
262 static void ipcomp_free_scratches(void)
267 if (--ipcomp_scratch_users)
270 scratches = ipcomp_scratches;
274 for_each_possible_cpu(i)
275 vfree(*per_cpu_ptr(scratches, i));
277 free_percpu(scratches);
280 static void **ipcomp_alloc_scratches(void)
285 if (ipcomp_scratch_users++)
286 return ipcomp_scratches;
288 scratches = alloc_percpu(void *);
292 ipcomp_scratches = scratches;
294 for_each_possible_cpu(i) {
295 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
298 *per_cpu_ptr(scratches, i) = scratch;
304 static void ipcomp_free_tfms(struct crypto_tfm **tfms)
306 struct ipcomp_tfms *pos;
309 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
310 if (pos->tfms == tfms)
319 list_del(&pos->list);
325 for_each_possible_cpu(cpu) {
326 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu);
327 crypto_free_tfm(tfm);
332 static struct crypto_tfm **ipcomp_alloc_tfms(const char *alg_name)
334 struct ipcomp_tfms *pos;
335 struct crypto_tfm **tfms;
338 /* This can be any valid CPU ID so we don't need locking. */
339 cpu = raw_smp_processor_id();
341 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
342 struct crypto_tfm *tfm;
345 tfm = *per_cpu_ptr(tfms, cpu);
347 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) {
353 pos = kmalloc(sizeof(*pos), GFP_KERNEL);
358 INIT_LIST_HEAD(&pos->list);
359 list_add(&pos->list, &ipcomp_tfms_list);
361 pos->tfms = tfms = alloc_percpu(struct crypto_tfm *);
365 for_each_possible_cpu(cpu) {
366 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0);
369 *per_cpu_ptr(tfms, cpu) = tfm;
375 ipcomp_free_tfms(tfms);
379 static void ipcomp_free_data(struct ipcomp_data *ipcd)
382 ipcomp_free_tfms(ipcd->tfms);
383 ipcomp_free_scratches();
386 static void ipcomp_destroy(struct xfrm_state *x)
388 struct ipcomp_data *ipcd = x->data;
391 xfrm_state_delete_tunnel(x);
392 mutex_lock(&ipcomp_resource_mutex);
393 ipcomp_free_data(ipcd);
394 mutex_unlock(&ipcomp_resource_mutex);
398 static int ipcomp_init_state(struct xfrm_state *x)
401 struct ipcomp_data *ipcd;
402 struct xfrm_algo_desc *calg_desc;
412 ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL);
416 memset(ipcd, 0, sizeof(*ipcd));
417 x->props.header_len = 0;
419 x->props.header_len += sizeof(struct iphdr);
421 mutex_lock(&ipcomp_resource_mutex);
422 if (!ipcomp_alloc_scratches())
425 ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
428 mutex_unlock(&ipcomp_resource_mutex);
431 err = ipcomp_tunnel_attach(x);
436 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
438 ipcd->threshold = calg_desc->uinfo.comp.threshold;
445 mutex_lock(&ipcomp_resource_mutex);
447 ipcomp_free_data(ipcd);
448 mutex_unlock(&ipcomp_resource_mutex);
453 static struct xfrm_type ipcomp_type = {
454 .description = "IPCOMP4",
455 .owner = THIS_MODULE,
456 .proto = IPPROTO_COMP,
457 .init_state = ipcomp_init_state,
458 .destructor = ipcomp_destroy,
459 .input = ipcomp_input,
460 .output = ipcomp_output
463 static struct net_protocol ipcomp4_protocol = {
464 .handler = xfrm4_rcv,
465 .err_handler = ipcomp4_err,
469 static int __init ipcomp4_init(void)
471 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
472 printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
475 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
476 printk(KERN_INFO "ipcomp init: can't add protocol\n");
477 xfrm_unregister_type(&ipcomp_type, AF_INET);
483 static void __exit ipcomp4_fini(void)
485 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
486 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
487 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
488 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
491 module_init(ipcomp4_init);
492 module_exit(ipcomp4_fini);
494 MODULE_LICENSE("GPL");
495 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
496 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");