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 + sizeof(struct ip_comp_hdr), scratch, dlen);
118 pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr));
124 static int ipcomp_output(struct sk_buff **pskb)
127 struct dst_entry *dst = (*pskb)->dst;
128 struct xfrm_state *x = dst->xfrm;
130 struct ip_comp_hdr *ipch;
131 struct ipcomp_data *ipcd = x->data;
134 iph = (*pskb)->nh.iph;
135 iph->tot_len = htons((*pskb)->len);
136 hdr_len = iph->ihl * 4;
137 if (((*pskb)->len - hdr_len) < ipcd->threshold) {
138 /* Don't bother compressing */
145 if ((skb_is_nonlinear(*pskb) || skb_cloned(*pskb)) &&
146 skb_linearize(*pskb, GFP_ATOMIC) != 0) {
151 err = ipcomp_compress(x, *pskb);
153 if (err == -EMSGSIZE) {
155 iph = (*pskb)->nh.iph;
163 /* Install ipcomp header, convert into ipcomp datagram. */
164 iph = (*pskb)->nh.iph;
165 iph->tot_len = htons((*pskb)->len);
166 ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4);
167 ipch->nexthdr = iph->protocol;
169 ipch->cpi = htons((u16 )ntohl(x->id.spi));
170 iph->protocol = IPPROTO_COMP;
180 static void ipcomp4_err(struct sk_buff *skb, u32 info)
183 struct iphdr *iph = (struct iphdr *)skb->data;
184 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
185 struct xfrm_state *x;
187 if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
188 skb->h.icmph->code != ICMP_FRAG_NEEDED)
191 spi = ntohl(ntohs(ipch->cpi));
192 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
193 spi, IPPROTO_COMP, AF_INET);
196 NETDEBUG(printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n",
197 spi, NIPQUAD(iph->daddr)));
201 /* We always hold one tunnel user reference to indicate a tunnel */
202 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
204 struct xfrm_state *t;
206 t = xfrm_state_alloc();
210 t->id.proto = IPPROTO_IPIP;
211 t->id.spi = x->props.saddr.a4;
212 t->id.daddr.a4 = x->id.daddr.a4;
213 memcpy(&t->sel, &x->sel, sizeof(t->sel));
214 t->props.family = AF_INET;
216 t->props.saddr.a4 = x->props.saddr.a4;
217 t->props.flags = x->props.flags;
219 t->type = xfrm_get_type(IPPROTO_IPIP, t->props.family);
223 if (t->type->init_state(t, NULL))
226 t->km.state = XFRM_STATE_VALID;
227 atomic_set(&t->tunnel_users, 1);
232 t->km.state = XFRM_STATE_DEAD;
239 * Must be protected by xfrm_cfg_sem. State and tunnel user references are
240 * always incremented on success.
242 static int ipcomp_tunnel_attach(struct xfrm_state *x)
245 struct xfrm_state *t;
247 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
248 x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
250 t = ipcomp_tunnel_create(x);
255 xfrm_state_insert(t);
259 atomic_inc(&t->tunnel_users);
264 static void ipcomp_free_data(struct ipcomp_data *ipcd)
267 crypto_free_tfm(ipcd->tfm);
269 kfree(ipcd->scratch);
272 static void ipcomp_destroy(struct xfrm_state *x)
274 struct ipcomp_data *ipcd = x->data;
277 xfrm_state_delete_tunnel(x);
278 ipcomp_free_data(ipcd);
282 static int ipcomp_init_state(struct xfrm_state *x, void *args)
285 struct ipcomp_data *ipcd;
286 struct xfrm_algo_desc *calg_desc;
293 ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL);
297 memset(ipcd, 0, sizeof(*ipcd));
298 x->props.header_len = 0;
300 x->props.header_len += sizeof(struct iphdr);
302 ipcd->scratch = kmalloc(IPCOMP_SCRATCH_SIZE, GFP_KERNEL);
306 ipcd->tfm = crypto_alloc_tfm(x->calg->alg_name, 0);
311 err = ipcomp_tunnel_attach(x);
316 calg_desc = xfrm_calg_get_byname(x->calg->alg_name);
318 ipcd->threshold = calg_desc->uinfo.comp.threshold;
326 ipcomp_free_data(ipcd);
332 static struct xfrm_type ipcomp_type = {
333 .description = "IPCOMP4",
334 .owner = THIS_MODULE,
335 .proto = IPPROTO_COMP,
336 .init_state = ipcomp_init_state,
337 .destructor = ipcomp_destroy,
338 .input = ipcomp_input,
339 .output = ipcomp_output
342 static struct net_protocol ipcomp4_protocol = {
343 .handler = xfrm4_rcv,
344 .err_handler = ipcomp4_err,
348 static int __init ipcomp4_init(void)
350 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
351 printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
354 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
355 printk(KERN_INFO "ipcomp init: can't add protocol\n");
356 xfrm_unregister_type(&ipcomp_type, AF_INET);
362 static void __exit ipcomp4_fini(void)
364 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
365 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
366 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
367 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
370 module_init(ipcomp4_init);
371 module_exit(ipcomp4_fini);
373 MODULE_LICENSE("GPL");
374 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
375 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");