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>
30 #include <net/ipcomp.h>
33 struct list_head list;
34 struct crypto_tfm **tfms;
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);
43 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);
76 iph->tot_len = htons(dlen + iph->ihl * 4);
82 static int ipcomp_input(struct xfrm_state *x,
83 struct xfrm_decap_state *decap, struct sk_buff *skb)
94 if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
95 skb_linearize(skb, GFP_ATOMIC) != 0) {
100 skb->ip_summed = CHECKSUM_NONE;
102 /* Remove ipcomp header and decompress original payload */
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);
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);
119 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
121 int err, plen, dlen, ihlen;
122 struct iphdr *iph = skb->nh.iph;
123 struct ipcomp_data *ipcd = x->data;
125 struct crypto_tfm *tfm;
128 ihlen = iph->ihl * 4;
129 plen = skb->len - ihlen;
130 dlen = IPCOMP_SCRATCH_SIZE;
131 start = skb->data + ihlen;
134 scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
135 tfm = *per_cpu_ptr(ipcd->tfms, cpu);
137 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
141 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
146 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
149 pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr));
157 static int ipcomp_output(struct sk_buff *skb)
160 struct dst_entry *dst = skb->dst;
161 struct xfrm_state *x = dst->xfrm;
163 struct ip_comp_hdr *ipch;
164 struct ipcomp_data *ipcd = x->data;
168 iph->tot_len = htons(skb->len);
169 hdr_len = iph->ihl * 4;
170 if ((skb->len - hdr_len) < ipcd->threshold) {
171 /* Don't bother compressing */
178 if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
179 skb_linearize(skb, GFP_ATOMIC) != 0) {
184 err = ipcomp_compress(x, skb);
186 if (err == -EMSGSIZE) {
196 /* Install ipcomp header, convert into ipcomp datagram. */
198 iph->tot_len = htons(skb->len);
199 ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4);
200 ipch->nexthdr = iph->protocol;
202 ipch->cpi = htons((u16 )ntohl(x->id.spi));
203 iph->protocol = IPPROTO_COMP;
213 static void ipcomp4_err(struct sk_buff *skb, u32 info)
216 struct iphdr *iph = (struct iphdr *)skb->data;
217 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
218 struct xfrm_state *x;
220 if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
221 skb->h.icmph->code != ICMP_FRAG_NEEDED)
224 spi = ntohl(ntohs(ipch->cpi));
225 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
226 spi, IPPROTO_COMP, AF_INET);
229 NETDEBUG(printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n",
230 spi, NIPQUAD(iph->daddr)));
234 /* We always hold one tunnel user reference to indicate a tunnel */
235 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
237 struct xfrm_state *t;
239 t = xfrm_state_alloc();
243 t->id.proto = IPPROTO_IPIP;
244 t->id.spi = x->props.saddr.a4;
245 t->id.daddr.a4 = x->id.daddr.a4;
246 memcpy(&t->sel, &x->sel, sizeof(t->sel));
247 t->props.family = AF_INET;
249 t->props.saddr.a4 = x->props.saddr.a4;
250 t->props.flags = x->props.flags;
252 t->type = xfrm_get_type(IPPROTO_IPIP, t->props.family);
256 if (t->type->init_state(t, NULL))
259 t->km.state = XFRM_STATE_VALID;
260 atomic_set(&t->tunnel_users, 1);
265 t->km.state = XFRM_STATE_DEAD;
272 * Must be protected by xfrm_cfg_sem. State and tunnel user references are
273 * always incremented on success.
275 static int ipcomp_tunnel_attach(struct xfrm_state *x)
278 struct xfrm_state *t;
280 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
281 x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
283 t = ipcomp_tunnel_create(x);
288 xfrm_state_insert(t);
292 atomic_inc(&t->tunnel_users);
297 static void ipcomp_free_scratches(void)
302 if (--ipcomp_scratch_users)
305 scratches = ipcomp_scratches;
310 void *scratch = *per_cpu_ptr(scratches, i);
315 free_percpu(scratches);
318 static void **ipcomp_alloc_scratches(void)
323 if (ipcomp_scratch_users++)
324 return ipcomp_scratches;
326 scratches = alloc_percpu(void *);
330 ipcomp_scratches = scratches;
333 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
336 *per_cpu_ptr(scratches, i) = scratch;
342 static void ipcomp_free_tfms(struct crypto_tfm **tfms)
344 struct ipcomp_tfms *pos;
347 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
348 if (pos->tfms == tfms)
357 list_del(&pos->list);
364 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu);
366 crypto_free_tfm(tfm);
371 static struct crypto_tfm **ipcomp_alloc_tfms(const char *alg_name)
373 struct ipcomp_tfms *pos;
374 struct crypto_tfm **tfms;
377 /* This can be any valid CPU ID so we don't need locking. */
378 cpu = smp_processor_id();
380 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
381 struct crypto_tfm *tfm;
384 tfm = *per_cpu_ptr(tfms, cpu);
386 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) {
392 pos = kmalloc(sizeof(*pos), GFP_KERNEL);
397 INIT_LIST_HEAD(&pos->list);
398 list_add(&pos->list, &ipcomp_tfms_list);
400 pos->tfms = tfms = alloc_percpu(struct crypto_tfm *);
405 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0);
408 *per_cpu_ptr(tfms, cpu) = tfm;
414 ipcomp_free_tfms(tfms);
418 static void ipcomp_free_data(struct ipcomp_data *ipcd)
421 ipcomp_free_tfms(ipcd->tfms);
422 ipcomp_free_scratches();
425 static void ipcomp_destroy(struct xfrm_state *x)
427 struct ipcomp_data *ipcd = x->data;
430 xfrm_state_delete_tunnel(x);
431 down(&ipcomp_resource_sem);
432 ipcomp_free_data(ipcd);
433 up(&ipcomp_resource_sem);
437 static int ipcomp_init_state(struct xfrm_state *x, void *args)
440 struct ipcomp_data *ipcd;
441 struct xfrm_algo_desc *calg_desc;
451 ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL);
455 memset(ipcd, 0, sizeof(*ipcd));
456 x->props.header_len = 0;
458 x->props.header_len += sizeof(struct iphdr);
460 down(&ipcomp_resource_sem);
461 if (!ipcomp_alloc_scratches())
464 ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
467 up(&ipcomp_resource_sem);
470 err = ipcomp_tunnel_attach(x);
475 calg_desc = xfrm_calg_get_byname(x->calg->alg_name);
477 ipcd->threshold = calg_desc->uinfo.comp.threshold;
484 down(&ipcomp_resource_sem);
486 ipcomp_free_data(ipcd);
487 up(&ipcomp_resource_sem);
492 static struct xfrm_type ipcomp_type = {
493 .description = "IPCOMP4",
494 .owner = THIS_MODULE,
495 .proto = IPPROTO_COMP,
496 .init_state = ipcomp_init_state,
497 .destructor = ipcomp_destroy,
498 .input = ipcomp_input,
499 .output = ipcomp_output
502 static struct net_protocol ipcomp4_protocol = {
503 .handler = xfrm4_rcv,
504 .err_handler = ipcomp4_err,
508 static int __init ipcomp4_init(void)
510 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
511 printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
514 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
515 printk(KERN_INFO "ipcomp init: can't add protocol\n");
516 xfrm_unregister_type(&ipcomp_type, AF_INET);
522 static void __exit ipcomp4_fini(void)
524 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
525 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
526 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
527 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
530 module_init(ipcomp4_init);
531 module_exit(ipcomp4_fini);
533 MODULE_LICENSE("GPL");
534 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
535 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");