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_comp **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)
46 struct ipcomp_data *ipcd = x->data;
47 const int plen = skb->len;
48 int dlen = IPCOMP_SCRATCH_SIZE;
49 const u8 *start = skb->data;
50 const int cpu = get_cpu();
51 u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
52 struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
53 int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
58 if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
63 err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
67 skb->truesize += dlen - plen;
68 __skb_put(skb, dlen - plen);
69 skb_copy_to_linear_data(skb, scratch, dlen);
75 static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
79 struct ip_comp_hdr *ipch;
81 if (skb_linearize_cow(skb))
84 skb->ip_summed = CHECKSUM_NONE;
86 /* Remove ipcomp header and decompress original payload */
88 ipch = (void *)skb->data;
89 iph->protocol = ipch->nexthdr;
90 skb->transport_header = skb->network_header + sizeof(*ipch);
91 __skb_pull(skb, sizeof(*ipch));
92 err = ipcomp_decompress(x, skb);
98 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
100 struct ipcomp_data *ipcd = x->data;
101 const int ihlen = skb_transport_offset(skb);
102 const int plen = skb->len - ihlen;
103 int dlen = IPCOMP_SCRATCH_SIZE;
104 u8 *start = skb_transport_header(skb);
105 const int cpu = get_cpu();
106 u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
107 struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
108 int err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
113 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
118 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
121 pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr));
129 static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
132 struct ip_comp_hdr *ipch;
133 struct ipcomp_data *ipcd = x->data;
135 struct iphdr *iph = ip_hdr(skb);
137 skb_push(skb, -skb_network_offset(skb));
138 iph->tot_len = htons(skb->len);
139 hdr_len = iph->ihl * 4;
140 if ((skb->len - hdr_len) < ipcd->threshold) {
141 /* Don't bother compressing */
145 if (skb_linearize_cow(skb))
148 err = ipcomp_compress(x, skb);
155 /* Install ipcomp header, convert into ipcomp datagram. */
156 iph->tot_len = htons(skb->len);
157 ipch = ip_comp_hdr(skb);
158 ipch->nexthdr = *skb_mac_header(skb);
160 ipch->cpi = htons((u16 )ntohl(x->id.spi));
161 *skb_mac_header(skb) = IPPROTO_COMP;
166 if (x->props.mode == XFRM_MODE_TUNNEL)
171 static void ipcomp4_err(struct sk_buff *skb, u32 info)
174 struct iphdr *iph = (struct iphdr *)skb->data;
175 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
176 struct xfrm_state *x;
178 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
179 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
182 spi = htonl(ntohs(ipch->cpi));
183 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
184 spi, IPPROTO_COMP, AF_INET);
187 NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n",
188 spi, NIPQUAD(iph->daddr));
192 /* We always hold one tunnel user reference to indicate a tunnel */
193 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
195 struct xfrm_state *t;
196 u8 mode = XFRM_MODE_TUNNEL;
198 t = xfrm_state_alloc();
202 t->id.proto = IPPROTO_IPIP;
203 t->id.spi = x->props.saddr.a4;
204 t->id.daddr.a4 = x->id.daddr.a4;
205 memcpy(&t->sel, &x->sel, sizeof(t->sel));
206 t->props.family = AF_INET;
207 if (x->props.mode == XFRM_MODE_BEET)
208 mode = x->props.mode;
209 t->props.mode = mode;
210 t->props.saddr.a4 = x->props.saddr.a4;
211 t->props.flags = x->props.flags;
213 if (xfrm_init_state(t))
216 atomic_set(&t->tunnel_users, 1);
221 t->km.state = XFRM_STATE_DEAD;
228 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are
229 * always incremented on success.
231 static int ipcomp_tunnel_attach(struct xfrm_state *x)
234 struct xfrm_state *t;
236 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
237 x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
239 t = ipcomp_tunnel_create(x);
244 xfrm_state_insert(t);
248 atomic_inc(&t->tunnel_users);
253 static void ipcomp_free_scratches(void)
258 if (--ipcomp_scratch_users)
261 scratches = ipcomp_scratches;
265 for_each_possible_cpu(i)
266 vfree(*per_cpu_ptr(scratches, i));
268 free_percpu(scratches);
271 static void **ipcomp_alloc_scratches(void)
276 if (ipcomp_scratch_users++)
277 return ipcomp_scratches;
279 scratches = alloc_percpu(void *);
283 ipcomp_scratches = scratches;
285 for_each_possible_cpu(i) {
286 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
289 *per_cpu_ptr(scratches, i) = scratch;
295 static void ipcomp_free_tfms(struct crypto_comp **tfms)
297 struct ipcomp_tfms *pos;
300 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
301 if (pos->tfms == tfms)
310 list_del(&pos->list);
316 for_each_possible_cpu(cpu) {
317 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
318 crypto_free_comp(tfm);
323 static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name)
325 struct ipcomp_tfms *pos;
326 struct crypto_comp **tfms;
329 /* This can be any valid CPU ID so we don't need locking. */
330 cpu = raw_smp_processor_id();
332 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
333 struct crypto_comp *tfm;
336 tfm = *per_cpu_ptr(tfms, cpu);
338 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
344 pos = kmalloc(sizeof(*pos), GFP_KERNEL);
349 INIT_LIST_HEAD(&pos->list);
350 list_add(&pos->list, &ipcomp_tfms_list);
352 pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
356 for_each_possible_cpu(cpu) {
357 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
361 *per_cpu_ptr(tfms, cpu) = tfm;
367 ipcomp_free_tfms(tfms);
371 static void ipcomp_free_data(struct ipcomp_data *ipcd)
374 ipcomp_free_tfms(ipcd->tfms);
375 ipcomp_free_scratches();
378 static void ipcomp_destroy(struct xfrm_state *x)
380 struct ipcomp_data *ipcd = x->data;
383 xfrm_state_delete_tunnel(x);
384 mutex_lock(&ipcomp_resource_mutex);
385 ipcomp_free_data(ipcd);
386 mutex_unlock(&ipcomp_resource_mutex);
390 static int ipcomp_init_state(struct xfrm_state *x)
393 struct ipcomp_data *ipcd;
394 struct xfrm_algo_desc *calg_desc;
404 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
408 x->props.header_len = 0;
409 if (x->props.mode == XFRM_MODE_TUNNEL)
410 x->props.header_len += sizeof(struct iphdr);
412 mutex_lock(&ipcomp_resource_mutex);
413 if (!ipcomp_alloc_scratches())
416 ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
419 mutex_unlock(&ipcomp_resource_mutex);
421 if (x->props.mode == XFRM_MODE_TUNNEL) {
422 err = ipcomp_tunnel_attach(x);
427 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
429 ipcd->threshold = calg_desc->uinfo.comp.threshold;
436 mutex_lock(&ipcomp_resource_mutex);
438 ipcomp_free_data(ipcd);
439 mutex_unlock(&ipcomp_resource_mutex);
444 static struct xfrm_type ipcomp_type = {
445 .description = "IPCOMP4",
446 .owner = THIS_MODULE,
447 .proto = IPPROTO_COMP,
448 .init_state = ipcomp_init_state,
449 .destructor = ipcomp_destroy,
450 .input = ipcomp_input,
451 .output = ipcomp_output
454 static struct net_protocol ipcomp4_protocol = {
455 .handler = xfrm4_rcv,
456 .err_handler = ipcomp4_err,
460 static int __init ipcomp4_init(void)
462 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
463 printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
466 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
467 printk(KERN_INFO "ipcomp init: can't add protocol\n");
468 xfrm_unregister_type(&ipcomp_type, AF_INET);
474 static void __exit ipcomp4_fini(void)
476 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
477 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
478 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
479 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
482 module_init(ipcomp4_init);
483 module_exit(ipcomp4_fini);
485 MODULE_LICENSE("GPL");
486 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
487 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
489 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP);