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linux/net/ipv4/ipcomp.c

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/*
* IP Payload Compression Protocol (IPComp) - RFC3173.
*
* Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* Todo:
* - Tunable compression parameters.
* - Compression stats.
* - Adaptive compression.
*/
#include <linux/module.h>
#include <asm/scatterlist.h>
#include <asm/semaphore.h>
#include <linux/crypto.h>
#include <linux/pfkeyv2.h>
#include <linux/percpu.h>
#include <linux/smp.h>
#include <linux/list.h>
#include <linux/vmalloc.h>
#include <linux/rtnetlink.h>
#include <linux/mutex.h>
#include <net/ip.h>
#include <net/xfrm.h>
#include <net/icmp.h>
#include <net/ipcomp.h>
#include <net/protocol.h>
struct ipcomp_tfms {
struct list_head list;
struct crypto_comp **tfms;
int users;
};
static DEFINE_MUTEX(ipcomp_resource_mutex);
static void **ipcomp_scratches;
static int ipcomp_scratch_users;
static LIST_HEAD(ipcomp_tfms_list);
static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
{
int err, plen, dlen;
struct ipcomp_data *ipcd = x->data;
u8 *start, *scratch;
struct crypto_comp *tfm;
int cpu;
plen = skb->len;
dlen = IPCOMP_SCRATCH_SIZE;
start = skb->data;
cpu = get_cpu();
scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
tfm = *per_cpu_ptr(ipcd->tfms, cpu);
err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
if (err)
goto out;
if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
err = -EINVAL;
goto out;
}
err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
if (err)
goto out;
skb->truesize += dlen - plen;
__skb_put(skb, dlen - plen);
memcpy(skb->data, scratch, dlen);
out:
put_cpu();
return err;
}
static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
{
int err = -ENOMEM;
struct iphdr *iph;
struct ip_comp_hdr *ipch;
if (skb_linearize_cow(skb))
goto out;
skb->ip_summed = CHECKSUM_NONE;
/* Remove ipcomp header and decompress original payload */
iph = skb->nh.iph;
ipch = (void *)skb->data;
iph->protocol = ipch->nexthdr;
skb->h.raw = skb->nh.raw + sizeof(*ipch);
__skb_pull(skb, sizeof(*ipch));
err = ipcomp_decompress(x, skb);
out:
return err;
}
static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
{
int err, plen, dlen, ihlen;
struct iphdr *iph = skb->nh.iph;
struct ipcomp_data *ipcd = x->data;
u8 *start, *scratch;
struct crypto_comp *tfm;
int cpu;
ihlen = iph->ihl * 4;
plen = skb->len - ihlen;
dlen = IPCOMP_SCRATCH_SIZE;
start = skb->data + ihlen;
cpu = get_cpu();
scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
tfm = *per_cpu_ptr(ipcd->tfms, cpu);
err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
if (err)
goto out;
if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
err = -EMSGSIZE;
goto out;
}
memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
put_cpu();
pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr));
return 0;
out:
put_cpu();
return err;
}
static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
{
int err;
struct iphdr *iph;
struct ip_comp_hdr *ipch;
struct ipcomp_data *ipcd = x->data;
int hdr_len = 0;
iph = skb->nh.iph;
iph->tot_len = htons(skb->len);
hdr_len = iph->ihl * 4;
if ((skb->len - hdr_len) < ipcd->threshold) {
/* Don't bother compressing */
goto out_ok;
}
if (skb_linearize_cow(skb))
goto out_ok;
err = ipcomp_compress(x, skb);
iph = skb->nh.iph;
if (err) {
goto out_ok;
}
/* Install ipcomp header, convert into ipcomp datagram. */
iph->tot_len = htons(skb->len);
ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4);
ipch->nexthdr = iph->protocol;
ipch->flags = 0;
ipch->cpi = htons((u16 )ntohl(x->id.spi));
iph->protocol = IPPROTO_COMP;
ip_send_check(iph);
return 0;
out_ok:
if (x->props.mode)
ip_send_check(iph);
return 0;
}
static void ipcomp4_err(struct sk_buff *skb, u32 info)
{
u32 spi;
struct iphdr *iph = (struct iphdr *)skb->data;
struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
struct xfrm_state *x;
if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
skb->h.icmph->code != ICMP_FRAG_NEEDED)
return;
spi = htonl(ntohs(ipch->cpi));
x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
spi, IPPROTO_COMP, AF_INET);
if (!x)
return;
NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n",
spi, NIPQUAD(iph->daddr));
xfrm_state_put(x);
}
/* We always hold one tunnel user reference to indicate a tunnel */
static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
{
struct xfrm_state *t;
t = xfrm_state_alloc();
if (t == NULL)
goto out;
t->id.proto = IPPROTO_IPIP;
t->id.spi = x->props.saddr.a4;
t->id.daddr.a4 = x->id.daddr.a4;
memcpy(&t->sel, &x->sel, sizeof(t->sel));
t->props.family = AF_INET;
t->props.mode = 1;
t->props.saddr.a4 = x->props.saddr.a4;
t->props.flags = x->props.flags;
if (xfrm_init_state(t))
goto error;
atomic_set(&t->tunnel_users, 1);
out:
return t;
error:
t->km.state = XFRM_STATE_DEAD;
xfrm_state_put(t);
t = NULL;
goto out;
}
/*
* Must be protected by xfrm_cfg_mutex. State and tunnel user references are
* always incremented on success.
*/
static int ipcomp_tunnel_attach(struct xfrm_state *x)
{
int err = 0;
struct xfrm_state *t;
t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
if (!t) {
t = ipcomp_tunnel_create(x);
if (!t) {
err = -EINVAL;
goto out;
}
xfrm_state_insert(t);
xfrm_state_hold(t);
}
x->tunnel = t;
atomic_inc(&t->tunnel_users);
out:
return err;
}
static void ipcomp_free_scratches(void)
{
int i;
void **scratches;
if (--ipcomp_scratch_users)
return;
scratches = ipcomp_scratches;
if (!scratches)
return;
for_each_possible_cpu(i)
vfree(*per_cpu_ptr(scratches, i));
free_percpu(scratches);
}
static void **ipcomp_alloc_scratches(void)
{
int i;
void **scratches;
if (ipcomp_scratch_users++)
return ipcomp_scratches;
scratches = alloc_percpu(void *);
if (!scratches)
return NULL;
ipcomp_scratches = scratches;
for_each_possible_cpu(i) {
void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
if (!scratch)
return NULL;
*per_cpu_ptr(scratches, i) = scratch;
}
return scratches;
}
static void ipcomp_free_tfms(struct crypto_comp **tfms)
{
struct ipcomp_tfms *pos;
int cpu;
list_for_each_entry(pos, &ipcomp_tfms_list, list) {
if (pos->tfms == tfms)
break;
}
BUG_TRAP(pos);
if (--pos->users)
return;
list_del(&pos->list);
kfree(pos);
if (!tfms)
return;
for_each_possible_cpu(cpu) {
struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
crypto_free_comp(tfm);
}
free_percpu(tfms);
}
static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name)
{
struct ipcomp_tfms *pos;
struct crypto_comp **tfms;
int cpu;
/* This can be any valid CPU ID so we don't need locking. */
cpu = raw_smp_processor_id();
list_for_each_entry(pos, &ipcomp_tfms_list, list) {
struct crypto_comp *tfm;
tfms = pos->tfms;
tfm = *per_cpu_ptr(tfms, cpu);
if (!strcmp(crypto_comp_name(tfm), alg_name)) {
pos->users++;
return tfms;
}
}
pos = kmalloc(sizeof(*pos), GFP_KERNEL);
if (!pos)
return NULL;
pos->users = 1;
INIT_LIST_HEAD(&pos->list);
list_add(&pos->list, &ipcomp_tfms_list);
pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
if (!tfms)
goto error;
for_each_possible_cpu(cpu) {
struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
CRYPTO_ALG_ASYNC);
if (!tfm)
goto error;
*per_cpu_ptr(tfms, cpu) = tfm;
}
return tfms;
error:
ipcomp_free_tfms(tfms);
return NULL;
}
static void ipcomp_free_data(struct ipcomp_data *ipcd)
{
if (ipcd->tfms)
ipcomp_free_tfms(ipcd->tfms);
ipcomp_free_scratches();
}
static void ipcomp_destroy(struct xfrm_state *x)
{
struct ipcomp_data *ipcd = x->data;
if (!ipcd)
return;
xfrm_state_delete_tunnel(x);
mutex_lock(&ipcomp_resource_mutex);
ipcomp_free_data(ipcd);
mutex_unlock(&ipcomp_resource_mutex);
kfree(ipcd);
}
static int ipcomp_init_state(struct xfrm_state *x)
{
int err;
struct ipcomp_data *ipcd;
struct xfrm_algo_desc *calg_desc;
err = -EINVAL;
if (!x->calg)
goto out;
if (x->encap)
goto out;
err = -ENOMEM;
ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
if (!ipcd)
goto out;
x->props.header_len = 0;
if (x->props.mode)
x->props.header_len += sizeof(struct iphdr);
mutex_lock(&ipcomp_resource_mutex);
if (!ipcomp_alloc_scratches())
goto error;
ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
if (!ipcd->tfms)
goto error;
mutex_unlock(&ipcomp_resource_mutex);
if (x->props.mode) {
err = ipcomp_tunnel_attach(x);
if (err)
goto error_tunnel;
}
calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
BUG_ON(!calg_desc);
ipcd->threshold = calg_desc->uinfo.comp.threshold;
x->data = ipcd;
err = 0;
out:
return err;
error_tunnel:
mutex_lock(&ipcomp_resource_mutex);
error:
ipcomp_free_data(ipcd);
mutex_unlock(&ipcomp_resource_mutex);
kfree(ipcd);
goto out;
}
static struct xfrm_type ipcomp_type = {
.description = "IPCOMP4",
.owner = THIS_MODULE,
.proto = IPPROTO_COMP,
.init_state = ipcomp_init_state,
.destructor = ipcomp_destroy,
.input = ipcomp_input,
.output = ipcomp_output
};
static struct net_protocol ipcomp4_protocol = {
.handler = xfrm4_rcv,
.err_handler = ipcomp4_err,
.no_policy = 1,
};
static int __init ipcomp4_init(void)
{
if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
return -EAGAIN;
}
if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
printk(KERN_INFO "ipcomp init: can't add protocol\n");
xfrm_unregister_type(&ipcomp_type, AF_INET);
return -EAGAIN;
}
return 0;
}
static void __exit ipcomp4_fini(void)
{
if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
}
module_init(ipcomp4_init);
module_exit(ipcomp4_fini);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
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