2 * IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173
4 * Copyright (C)2003 USAGI/WIDE Project
6 * Author Mitsuru KANDA <mk@linux-ipv6.org>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
26 * The compression of IP datagram MUST be done before AH/ESP processing,
27 * fragmentation, and the addition of Hop-by-Hop/Routing header.
30 * The decompression of IP datagram MUST be done after the reassembly,
33 #include <linux/config.h>
34 #include <linux/module.h>
35 #include <net/inet_ecn.h>
38 #include <net/ipcomp.h>
39 #include <asm/scatterlist.h>
40 #include <linux/crypto.h>
41 #include <linux/pfkeyv2.h>
42 #include <linux/random.h>
45 #include <linux/ipv6.h>
46 #include <linux/icmpv6.h>
48 static int ipcomp6_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct sk_buff *skb)
53 int hdr_len = skb->h.raw - skb->nh.raw;
54 unsigned char *tmp_hdr = NULL;
57 struct ipcomp_data *ipcd = x->data;
58 u8 *start, *scratch = ipcd->scratch;
60 if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
61 skb_linearize(skb, GFP_ATOMIC) != 0) {
66 skb->ip_summed = CHECKSUM_NONE;
68 /* Remove ipcomp header and decompress original payload */
70 tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
73 memcpy(tmp_hdr, iph, hdr_len);
74 nexthdr = *(u8 *)skb->data;
75 skb_pull(skb, sizeof(struct ipv6_comp_hdr));
76 skb->nh.raw += sizeof(struct ipv6_comp_hdr);
77 memcpy(skb->nh.raw, tmp_hdr, hdr_len);
79 iph->payload_len = htons(ntohs(iph->payload_len) - sizeof(struct ipv6_comp_hdr));
80 skb->h.raw = skb->data;
84 dlen = IPCOMP_SCRATCH_SIZE;
87 err = crypto_comp_decompress(ipcd->tfm, start, plen, scratch, &dlen);
93 if (dlen < (plen + sizeof(struct ipv6_comp_hdr))) {
98 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
103 skb_put(skb, dlen - plen);
104 memcpy(skb->data, scratch, dlen);
107 iph->payload_len = htons(skb->len);
109 ip6_find_1stfragopt(skb, &prevhdr);
121 static int ipcomp6_output(struct sk_buff *skb)
124 struct dst_entry *dst = skb->dst;
125 struct xfrm_state *x = dst->xfrm;
126 struct ipv6hdr *tmp_iph = NULL, *iph, *top_iph;
128 struct ipv6_comp_hdr *ipch;
129 struct ipcomp_data *ipcd = x->data;
133 u8 *start, *scratch = ipcd->scratch;
135 if (skb->ip_summed == CHECKSUM_HW && skb_checksum_help(skb) == NULL) {
140 spin_lock_bh(&x->lock);
142 err = xfrm_check_output(x, skb, AF_INET6);
147 hdr_len = sizeof(struct ipv6hdr);
148 nexthdr = IPPROTO_IPV6;
150 top_iph = (struct ipv6hdr *)skb_push(skb, sizeof(struct ipv6hdr));
151 top_iph->version = 6;
152 top_iph->priority = iph->priority;
153 top_iph->flow_lbl[0] = iph->flow_lbl[0];
154 top_iph->flow_lbl[1] = iph->flow_lbl[1];
155 top_iph->flow_lbl[2] = iph->flow_lbl[2];
156 top_iph->nexthdr = IPPROTO_IPV6; /* initial */
157 top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
158 top_iph->hop_limit = iph->hop_limit;
159 memcpy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr, sizeof(struct in6_addr));
160 memcpy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr, sizeof(struct in6_addr));
161 skb->nh.raw = skb->data; /* == top_iph */
162 skb->h.raw = skb->nh.raw + hdr_len;
164 hdr_len = ip6_find_1stfragopt(skb, &prevhdr);
168 /* check whether datagram len is larger than threshold */
169 if ((skb->len - hdr_len) < ipcd->threshold) {
173 if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
174 skb_linearize(skb, GFP_ATOMIC) != 0) {
180 plen = skb->len - hdr_len;
181 dlen = IPCOMP_SCRATCH_SIZE;
182 start = skb->data + hdr_len;
184 err = crypto_comp_compress(ipcd->tfm, start, plen, scratch, &dlen);
188 if ((dlen + sizeof(struct ipv6_comp_hdr)) >= plen) {
191 memcpy(start, scratch, dlen);
192 pskb_trim(skb, hdr_len+dlen);
194 /* insert ipcomp header and replace datagram */
195 tmp_iph = kmalloc(hdr_len, GFP_ATOMIC);
200 memcpy(tmp_iph, skb->nh.raw, hdr_len);
201 top_iph = (struct ipv6hdr*)skb_push(skb, sizeof(struct ipv6_comp_hdr));
202 memcpy(top_iph, tmp_iph, hdr_len);
205 if (x->props.mode && (x->props.flags & XFRM_STATE_NOECN))
206 IP6_ECN_clear(top_iph);
207 top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
208 skb->nh.raw = skb->data; /* top_iph */
209 ip6_find_1stfragopt(skb, &prevhdr);
210 *prevhdr = IPPROTO_COMP;
212 ipch = (struct ipv6_comp_hdr *)((unsigned char *)top_iph + hdr_len);
213 ipch->nexthdr = nexthdr;
215 ipch->cpi = htons((u16 )ntohl(x->id.spi));
217 skb->h.raw = (unsigned char*)ipch;
219 x->curlft.bytes += skb->len;
221 spin_unlock_bh(&x->lock);
223 if ((skb->dst = dst_pop(dst)) == NULL) {
227 err = NET_XMIT_BYPASS;
232 spin_unlock_bh(&x->lock);
238 static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
239 int type, int code, int offset, __u32 info)
242 struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;
243 struct ipv6_comp_hdr *ipcomph = (struct ipv6_comp_hdr*)(skb->data+offset);
244 struct xfrm_state *x;
246 if (type != ICMPV6_DEST_UNREACH || type != ICMPV6_PKT_TOOBIG)
249 spi = ntohl(ntohs(ipcomph->cpi));
250 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, spi, IPPROTO_COMP, AF_INET6);
254 printk(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/"
255 "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n",
256 spi, NIP6(iph->daddr));
260 static void ipcomp6_free_data(struct ipcomp_data *ipcd)
263 crypto_free_tfm(ipcd->tfm);
265 kfree(ipcd->scratch);
268 static void ipcomp6_destroy(struct xfrm_state *x)
270 struct ipcomp_data *ipcd = x->data;
273 ipcomp6_free_data(ipcd);
277 static int ipcomp6_init_state(struct xfrm_state *x, void *args)
280 struct ipcomp_data *ipcd;
281 struct xfrm_algo_desc *calg_desc;
288 ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL);
292 memset(ipcd, 0, sizeof(*ipcd));
293 x->props.header_len = sizeof(struct ipv6_comp_hdr);
295 x->props.header_len += sizeof(struct ipv6hdr);
297 ipcd->scratch = kmalloc(IPCOMP_SCRATCH_SIZE, GFP_KERNEL);
301 ipcd->tfm = crypto_alloc_tfm(x->calg->alg_name, 0);
305 calg_desc = xfrm_calg_get_byname(x->calg->alg_name);
307 ipcd->threshold = calg_desc->uinfo.comp.threshold;
314 ipcomp6_free_data(ipcd);
321 static struct xfrm_type ipcomp6_type =
323 .description = "IPCOMP6",
324 .owner = THIS_MODULE,
325 .proto = IPPROTO_COMP,
326 .init_state = ipcomp6_init_state,
327 .destructor = ipcomp6_destroy,
328 .input = ipcomp6_input,
329 .output = ipcomp6_output,
332 static struct inet6_protocol ipcomp6_protocol =
334 .handler = xfrm6_rcv,
335 .err_handler = ipcomp6_err,
336 .flags = INET6_PROTO_NOPOLICY,
339 static int __init ipcomp6_init(void)
341 if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
342 printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");
345 if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
346 printk(KERN_INFO "ipcomp6 init: can't add protocol\n");
347 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
353 static void __exit ipcomp6_fini(void)
355 if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
356 printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");
357 if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
358 printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");
361 module_init(ipcomp6_init);
362 module_exit(ipcomp6_fini);
363 MODULE_LICENSE("GPL");
364 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
365 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");