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 <linux/crypto.h>
20 #include <linux/pfkeyv2.h>
21 #include <net/inet_ecn.h>
25 #include <net/ipcomp.h>
27 static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
31 struct ipcomp_data *ipcd = x->data;
32 u8 *start, *scratch = ipcd->scratch;
35 dlen = IPCOMP_SCRATCH_SIZE;
38 err = crypto_comp_decompress(ipcd->tfm, start, plen, scratch, &dlen);
42 if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
47 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
51 skb_put(skb, dlen - plen);
52 memcpy(skb->data, scratch, dlen);
54 iph->tot_len = htons(dlen + iph->ihl * 4);
59 static int ipcomp_input(struct xfrm_state *x,
60 struct xfrm_decap_state *decap, struct sk_buff *skb)
71 if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
72 skb_linearize(skb, GFP_ATOMIC) != 0) {
77 skb->ip_summed = CHECKSUM_NONE;
79 /* Remove ipcomp header and decompress original payload */
81 memcpy(&tmp_iph, iph, iph->ihl * 4);
82 nexthdr = *(u8 *)skb->data;
83 skb_pull(skb, sizeof(struct ip_comp_hdr));
84 skb->nh.raw += sizeof(struct ip_comp_hdr);
85 memcpy(skb->nh.raw, &tmp_iph, tmp_iph.iph.ihl * 4);
87 iph->tot_len = htons(ntohs(iph->tot_len) - sizeof(struct ip_comp_hdr));
88 iph->protocol = nexthdr;
89 skb->h.raw = skb->data;
90 err = ipcomp_decompress(x, skb);
96 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
98 int err, plen, dlen, ihlen;
99 struct iphdr *iph = skb->nh.iph;
100 struct ipcomp_data *ipcd = x->data;
101 u8 *start, *scratch = ipcd->scratch;
103 ihlen = iph->ihl * 4;
104 plen = skb->len - ihlen;
105 dlen = IPCOMP_SCRATCH_SIZE;
106 start = skb->data + ihlen;
108 err = crypto_comp_compress(ipcd->tfm, start, plen, scratch, &dlen);
112 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
117 memcpy(start, scratch, dlen);
118 pskb_trim(skb, ihlen + dlen);
124 static void ipcomp_tunnel_encap(struct xfrm_state *x, struct sk_buff *skb)
126 struct dst_entry *dst = skb->dst;
127 struct iphdr *iph, *top_iph;
130 top_iph = (struct iphdr *)skb_push(skb, sizeof(struct iphdr));
132 top_iph->version = 4;
133 top_iph->tos = iph->tos;
134 top_iph->tot_len = htons(skb->len);
135 if (!(iph->frag_off&htons(IP_DF)))
136 __ip_select_ident(top_iph, dst, 0);
137 top_iph->ttl = iph->ttl;
139 top_iph->saddr = x->props.saddr.a4;
140 top_iph->daddr = x->id.daddr.a4;
141 top_iph->frag_off = iph->frag_off&~htons(IP_MF|IP_OFFSET);
142 memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
143 skb->nh.raw = skb->data;
146 static int ipcomp_output(struct sk_buff **pskb)
149 struct dst_entry *dst = (*pskb)->dst;
150 struct xfrm_state *x = dst->xfrm;
151 struct iphdr *iph, *top_iph;
152 struct ip_comp_hdr *ipch;
153 struct ipcomp_data *ipcd = x->data;
160 if ((*pskb)->ip_summed == CHECKSUM_HW) {
161 err = skb_checksum_help(pskb, 0);
166 spin_lock_bh(&x->lock);
167 err = xfrm_check_output(x, *pskb, AF_INET);
171 /* Don't bother compressing */
172 if (!x->props.mode) {
173 iph = (*pskb)->nh.iph;
174 hdr_len = iph->ihl * 4;
176 if (((*pskb)->len - hdr_len) < ipcd->threshold) {
178 ipcomp_tunnel_encap(x, *pskb);
179 iph = (*pskb)->nh.iph;
180 iph->protocol = IPPROTO_IPIP;
187 ipcomp_tunnel_encap(x, *pskb);
189 if ((skb_is_nonlinear(*pskb) || skb_cloned(*pskb)) &&
190 skb_linearize(*pskb, GFP_ATOMIC) != 0) {
195 err = ipcomp_compress(x, *pskb);
197 if (err == -EMSGSIZE) {
199 iph = (*pskb)->nh.iph;
200 iph->protocol = IPPROTO_IPIP;
208 /* Install ipcomp header, convert into ipcomp datagram. */
209 iph = (*pskb)->nh.iph;
210 memcpy(&tmp_iph, iph, iph->ihl * 4);
211 top_iph = (struct iphdr *)skb_push(*pskb, sizeof(struct ip_comp_hdr));
212 memcpy(top_iph, &tmp_iph, iph->ihl * 4);
214 if (x->props.mode && (x->props.flags & XFRM_STATE_NOECN))
216 iph->tot_len = htons((*pskb)->len);
217 iph->protocol = IPPROTO_COMP;
219 ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4);
220 ipch->nexthdr = x->props.mode ? IPPROTO_IPIP : tmp_iph.iph.protocol;
222 ipch->cpi = htons((u16 )ntohl(x->id.spi));
224 (*pskb)->nh.raw = (*pskb)->data;
227 x->curlft.bytes += (*pskb)->len;
229 spin_unlock_bh(&x->lock);
231 if (((*pskb)->dst = dst_pop(dst)) == NULL) {
235 err = NET_XMIT_BYPASS;
240 spin_unlock_bh(&x->lock);
246 static void ipcomp4_err(struct sk_buff *skb, u32 info)
249 struct iphdr *iph = (struct iphdr *)skb->data;
250 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
251 struct xfrm_state *x;
253 if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
254 skb->h.icmph->code != ICMP_FRAG_NEEDED)
257 spi = ntohl(ntohs(ipch->cpi));
258 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
259 spi, IPPROTO_COMP, AF_INET);
262 NETDEBUG(printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n",
263 spi, NIPQUAD(iph->daddr)));
267 /* We always hold one tunnel user reference to indicate a tunnel */
268 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
270 struct xfrm_state *t;
272 t = xfrm_state_alloc();
276 t->id.proto = IPPROTO_IPIP;
277 t->id.spi = x->props.saddr.a4;
278 t->id.daddr.a4 = x->id.daddr.a4;
279 memcpy(&t->sel, &x->sel, sizeof(t->sel));
280 t->props.family = AF_INET;
282 t->props.saddr.a4 = x->props.saddr.a4;
283 t->props.flags = x->props.flags;
285 t->type = xfrm_get_type(IPPROTO_IPIP, t->props.family);
289 if (t->type->init_state(t, NULL))
292 t->km.state = XFRM_STATE_VALID;
293 atomic_set(&t->tunnel_users, 1);
298 t->km.state = XFRM_STATE_DEAD;
305 * Must be protected by xfrm_cfg_sem. State and tunnel user references are
306 * always incremented on success.
308 static int ipcomp_tunnel_attach(struct xfrm_state *x)
311 struct xfrm_state *t;
313 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
314 x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
316 t = ipcomp_tunnel_create(x);
321 xfrm_state_insert(t);
325 atomic_inc(&t->tunnel_users);
330 static void ipcomp_free_data(struct ipcomp_data *ipcd)
333 crypto_free_tfm(ipcd->tfm);
335 kfree(ipcd->scratch);
338 static void ipcomp_destroy(struct xfrm_state *x)
340 struct ipcomp_data *ipcd = x->data;
343 xfrm_state_delete_tunnel(x);
344 ipcomp_free_data(ipcd);
348 static int ipcomp_init_state(struct xfrm_state *x, void *args)
351 struct ipcomp_data *ipcd;
352 struct xfrm_algo_desc *calg_desc;
359 ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL);
363 memset(ipcd, 0, sizeof(*ipcd));
364 x->props.header_len = sizeof(struct ip_comp_hdr);
366 x->props.header_len += sizeof(struct iphdr);
368 ipcd->scratch = kmalloc(IPCOMP_SCRATCH_SIZE, GFP_KERNEL);
372 ipcd->tfm = crypto_alloc_tfm(x->calg->alg_name, 0);
377 err = ipcomp_tunnel_attach(x);
382 calg_desc = xfrm_calg_get_byname(x->calg->alg_name);
384 ipcd->threshold = calg_desc->uinfo.comp.threshold;
392 ipcomp_free_data(ipcd);
398 static struct xfrm_type ipcomp_type = {
399 .description = "IPCOMP4",
400 .owner = THIS_MODULE,
401 .proto = IPPROTO_COMP,
402 .init_state = ipcomp_init_state,
403 .destructor = ipcomp_destroy,
404 .input = ipcomp_input,
405 .output = ipcomp_output
408 static struct inet_protocol ipcomp4_protocol = {
409 .handler = xfrm4_rcv,
410 .err_handler = ipcomp4_err,
414 static int __init ipcomp4_init(void)
416 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
417 printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
420 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
421 printk(KERN_INFO "ipcomp init: can't add protocol\n");
422 xfrm_unregister_type(&ipcomp_type, AF_INET);
428 static void __exit ipcomp4_fini(void)
430 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
431 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
432 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
433 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
436 module_init(ipcomp4_init);
437 module_exit(ipcomp4_fini);
439 MODULE_LICENSE("GPL");
440 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
441 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");