net/xfrm/xfrm_ipcomp.c - linux - Git at Google

 /*
  * IP Payload Compression Protocol (IPComp) - RFC3173.
  *
  * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
  * Copyright (c) 2003-2008 Herbert Xu <herbert@gondor.apana.org.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/crypto.h>
 #include <linux/err.h>
 #include <linux/gfp.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/percpu.h>
 #include <linux/rtnetlink.h>
 #include <linux/smp.h>
 #include <linux/vmalloc.h>
 #include <net/ip.h>
 #include <net/ipcomp.h>
 #include <net/xfrm.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)
 {
 	struct ipcomp_data *ipcd = x->data;
 	const int plen = skb->len;
 	int dlen = IPCOMP_SCRATCH_SIZE;
 	const u8 *start = skb->data;
 	const int cpu = get_cpu();
 	u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
 	struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 	int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
 	int len;

 	if (err)
 		goto out;

 	if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
 		err = -EINVAL;
 		goto out;
 	}

 	len = dlen - plen;
 	if (len > skb_tailroom(skb))
 		len = skb_tailroom(skb);

 	skb->truesize += len;
 	__skb_put(skb, len);

 	len += plen;
 	skb_copy_to_linear_data(skb, scratch, len);

 	while ((scratch += len, dlen -= len) > 0) {
 		skb_frag_t *frag;

 		err = -EMSGSIZE;
 		if (WARN_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS))
 			goto out;

 		frag = skb_shinfo(skb)->frags + skb_shinfo(skb)->nr_frags;
 		frag->page = alloc_page(GFP_ATOMIC);

 		err = -ENOMEM;
 		if (!frag->page)
 			goto out;

 		len = PAGE_SIZE;
 		if (dlen < len)
 			len = dlen;

 		memcpy(page_address(frag->page), scratch, len);

 		frag->page_offset = 0;
 		frag->size = len;
 		skb->truesize += len;
 		skb->data_len += len;
 		skb->len += len;

 		skb_shinfo(skb)->nr_frags++;
 	}

 	err = 0;

 out:
 	put_cpu();
 	return err;
 }

 int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
 {
 	int nexthdr;
 	int err = -ENOMEM;
 	struct ip_comp_hdr *ipch;

 	if (skb_linearize_cow(skb))
 		goto out;

 	skb->ip_summed = CHECKSUM_NONE;

 	/* Remove ipcomp header and decompress original payload */
 	ipch = (void *)skb->data;
 	nexthdr = ipch->nexthdr;

 	skb->transport_header = skb->network_header + sizeof(*ipch);
 	__skb_pull(skb, sizeof(*ipch));
 	err = ipcomp_decompress(x, skb);
 	if (err)
 		goto out;

 	err = nexthdr;

 out:
 	return err;
 }
 EXPORT_SYMBOL_GPL(ipcomp_input);

 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
 {
 	struct ipcomp_data *ipcd = x->data;
 	const int plen = skb->len;
 	int dlen = IPCOMP_SCRATCH_SIZE;
 	u8 *start = skb->data;
 	const int cpu = get_cpu();
 	u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
 	struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 	int err;

 	local_bh_disable();
 	err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 	local_bh_enable();
 	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, dlen + sizeof(struct ip_comp_hdr));
 	return 0;

 out:
 	put_cpu();
 	return err;
 }

 int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
 {
 	int err;
 	struct ip_comp_hdr *ipch;
 	struct ipcomp_data *ipcd = x->data;

 	if (skb->len < ipcd->threshold) {
 		/* Don't bother compressing */
 		goto out_ok;
 	}

 	if (skb_linearize_cow(skb))
 		goto out_ok;

 	err = ipcomp_compress(x, skb);

 	if (err) {
 		goto out_ok;
 	}

 	/* Install ipcomp header, convert into ipcomp datagram. */
 	ipch = ip_comp_hdr(skb);
 	ipch->nexthdr = *skb_mac_header(skb);
 	ipch->flags = 0;
 	ipch->cpi = htons((u16 )ntohl(x->id.spi));
 	*skb_mac_header(skb) = IPPROTO_COMP;
 out_ok:
 	skb_push(skb, -skb_network_offset(skb));
 	return 0;
 }
 EXPORT_SYMBOL_GPL(ipcomp_output);

 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 (IS_ERR(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();
 }

 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);
 }
 EXPORT_SYMBOL_GPL(ipcomp_destroy);

 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;

 	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);

 	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:
 	ipcomp_free_data(ipcd);
 	mutex_unlock(&ipcomp_resource_mutex);
 	kfree(ipcd);
 	goto out;
 }
 EXPORT_SYMBOL_GPL(ipcomp_init_state);

 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
	/*
	* IP Payload Compression Protocol (IPComp) - RFC3173.
	*
	* Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
	* Copyright (c) 2003-2008 Herbert Xu <herbert@gondor.apana.org.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/crypto.h>
	#include <linux/err.h>
	#include <linux/gfp.h>
	#include <linux/list.h>
	#include <linux/module.h>
	#include <linux/mutex.h>
	#include <linux/percpu.h>
	#include <linux/rtnetlink.h>
	#include <linux/smp.h>
	#include <linux/vmalloc.h>
	#include <net/ip.h>
	#include <net/ipcomp.h>
	#include <net/xfrm.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)
	{
	struct ipcomp_data *ipcd = x->data;
	const int plen = skb->len;
	int dlen = IPCOMP_SCRATCH_SIZE;
	const u8 *start = skb->data;
	const int cpu = get_cpu();
	u8 scratch = per_cpu_ptr(ipcomp_scratches, cpu);
	struct crypto_comp tfm = per_cpu_ptr(ipcd->tfms, cpu);
	int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
	int len;

	if (err)
	goto out;

	if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
	err = -EINVAL;
	goto out;
	}

	len = dlen - plen;
	if (len > skb_tailroom(skb))
	len = skb_tailroom(skb);

	skb->truesize += len;
	__skb_put(skb, len);

	len += plen;
	skb_copy_to_linear_data(skb, scratch, len);

	while ((scratch += len, dlen -= len) > 0) {
	skb_frag_t *frag;

	err = -EMSGSIZE;
	if (WARN_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS))
	goto out;

	frag = skb_shinfo(skb)->frags + skb_shinfo(skb)->nr_frags;
	frag->page = alloc_page(GFP_ATOMIC);

	err = -ENOMEM;
	if (!frag->page)
	goto out;

	len = PAGE_SIZE;
	if (dlen < len)
	len = dlen;

	memcpy(page_address(frag->page), scratch, len);

	frag->page_offset = 0;
	frag->size = len;
	skb->truesize += len;
	skb->data_len += len;
	skb->len += len;

	skb_shinfo(skb)->nr_frags++;
	}

	err = 0;

	out:
	put_cpu();
	return err;
	}

	int ipcomp_input(struct xfrm_state x, struct sk_buff skb)
	{
	int nexthdr;
	int err = -ENOMEM;
	struct ip_comp_hdr *ipch;

	if (skb_linearize_cow(skb))
	goto out;

	skb->ip_summed = CHECKSUM_NONE;

	/* Remove ipcomp header and decompress original payload */
	ipch = (void *)skb->data;
	nexthdr = ipch->nexthdr;

	skb->transport_header = skb->network_header + sizeof(*ipch);
	__skb_pull(skb, sizeof(*ipch));
	err = ipcomp_decompress(x, skb);
	if (err)
	goto out;

	err = nexthdr;

	out:
	return err;
	}
	EXPORT_SYMBOL_GPL(ipcomp_input);

	static int ipcomp_compress(struct xfrm_state x, struct sk_buff skb)
	{
	struct ipcomp_data *ipcd = x->data;
	const int plen = skb->len;
	int dlen = IPCOMP_SCRATCH_SIZE;
	u8 *start = skb->data;
	const int cpu = get_cpu();
	u8 scratch = per_cpu_ptr(ipcomp_scratches, cpu);
	struct crypto_comp tfm = per_cpu_ptr(ipcd->tfms, cpu);
	int err;

	local_bh_disable();
	err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
	local_bh_enable();
	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, dlen + sizeof(struct ip_comp_hdr));
	return 0;

	out:
	put_cpu();
	return err;
	}

	int ipcomp_output(struct xfrm_state x, struct sk_buff skb)
	{
	int err;
	struct ip_comp_hdr *ipch;
	struct ipcomp_data *ipcd = x->data;

	if (skb->len < ipcd->threshold) {
	/* Don't bother compressing */
	goto out_ok;
	}

	if (skb_linearize_cow(skb))
	goto out_ok;

	err = ipcomp_compress(x, skb);

	if (err) {
	goto out_ok;
	}

	/* Install ipcomp header, convert into ipcomp datagram. */
	ipch = ip_comp_hdr(skb);
	ipch->nexthdr = *skb_mac_header(skb);
	ipch->flags = 0;
	ipch->cpi = htons((u16 )ntohl(x->id.spi));
	*skb_mac_header(skb) = IPPROTO_COMP;
	out_ok:
	skb_push(skb, -skb_network_offset(skb));
	return 0;
	}
	EXPORT_SYMBOL_GPL(ipcomp_output);

	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 (IS_ERR(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();
	}

	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);
	}
	EXPORT_SYMBOL_GPL(ipcomp_destroy);

	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;

	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);

	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:
	ipcomp_free_data(ipcd);
	mutex_unlock(&ipcomp_resource_mutex);
	kfree(ipcd);
	goto out;
	}
	EXPORT_SYMBOL_GPL(ipcomp_init_state);

	MODULE_LICENSE("GPL");
	MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
	MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");