/* * 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/config.h>#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 <net/ip.h>#include <net/xfrm.h>#include <net/icmp.h>#include <net/ipcomp.h> struct ipcomp_tfms {	struct list_head list;	struct crypto_tfm **tfms;	int users;}; static DECLARE_MUTEX(ipcomp_resource_sem);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 iphdr *iph;	struct ipcomp_data *ipcd = x->data;	u8 *start, *scratch;	struct crypto_tfm *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_put(skb, dlen - plen);	memcpy(skb->data, scratch, dlen);	iph = skb->nh.iph;	iph->tot_len = htons(dlen + iph->ihl * 4);out:		put_cpu();	return err;} static int ipcomp_input(struct xfrm_state *x,                        struct xfrm_decap_state *decap, struct sk_buff *skb){	u8 nexthdr;	int err = 0;	struct iphdr *iph;	union {		struct iphdr	iph;		char 		buf[60];	} tmp_iph;  	if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&	    skb_linearize(skb, GFP_ATOMIC) != 0) {	    	err = -ENOMEM;	    	goto out;	} 	skb->ip_summed = CHECKSUM_NONE; 	/* Remove ipcomp header and decompress original payload */		iph = skb->nh.iph;	memcpy(&tmp_iph, iph, iph->ihl * 4);	nexthdr = *(u8 *)skb->data;	skb_pull(skb, sizeof(struct ip_comp_hdr));	skb->nh.raw += sizeof(struct ip_comp_hdr);	memcpy(skb->nh.raw, &tmp_iph, tmp_iph.iph.ihl * 4);	iph = skb->nh.iph;	iph->tot_len = htons(ntohs(iph->tot_len) - sizeof(struct ip_comp_hdr));	iph->protocol = nexthdr;	skb->h.raw = skb->data;	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_tfm *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_is_nonlinear(skb) || skb_cloned(skb)) &&	    skb_linearize(skb, GFP_ATOMIC) != 0) {		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 = ntohl(ntohs(ipch->cpi));	x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,	                      spi, IPPROTO_COMP, AF_INET);	if (!x)		return;	NETDEBUG(printk(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_sem.  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_cpu(i) {		void *scratch = *per_cpu_ptr(scratches, i);		if (scratch)			vfree(scratch);	} 	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_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_tfm **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_cpu(cpu) {		struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu);		if (tfm)			crypto_free_tfm(tfm);	}	free_percpu(tfms);} static struct crypto_tfm **ipcomp_alloc_tfms(const char *alg_name){	struct ipcomp_tfms *pos;	struct crypto_tfm **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_tfm *tfm; 		tfms = pos->tfms;		tfm = *per_cpu_ptr(tfms, cpu); 		if (!strcmp(crypto_tfm_alg_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_tfm *);	if (!tfms)		goto error; 	for_each_cpu(cpu) {		struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0);		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);	down(&ipcomp_resource_sem);	ipcomp_free_data(ipcd);	up(&ipcomp_resource_sem);	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 = kmalloc(sizeof(*ipcd), GFP_KERNEL);	if (!ipcd)		goto out; 	memset(ipcd, 0, sizeof(*ipcd));	x->props.header_len = 0;	if (x->props.mode)		x->props.header_len += sizeof(struct iphdr); 	down(&ipcomp_resource_sem);	if (!ipcomp_alloc_scratches())		goto error; 	ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);	if (!ipcd->tfms)		goto error;	up(&ipcomp_resource_sem); 	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:	down(&ipcomp_resource_sem);error:	ipcomp_free_data(ipcd);	up(&ipcomp_resource_sem);	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;

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