[linux.git] / net / xfrm / xfrm_ipcomp.c

/*
 * IP Payload Compression Protocol (IPComp) - RFC3173.
 *
 * Copyright (c) 2003 James Morris <[email protected]>
 * Copyright (c) 2003-2008 Herbert Xu <[email protected]>
 *
 * 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/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/percpu.h>
#include <linux/slab.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 * __percpu *tfms;
	int users;
};

static DEFINE_MUTEX(ipcomp_resource_mutex);
static void * __percpu *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_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 * __percpu *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 * __percpu *ipcomp_alloc_scratches(void)
{
	int i;
	void * __percpu *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 * __percpu *tfms)
{
	struct ipcomp_tfms *pos;
	int cpu;

	list_for_each_entry(pos, &ipcomp_tfms_list, list) {
		if (pos->tfms == tfms)
			break;
	}

	WARN_ON(!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 * __percpu *ipcomp_alloc_tfms(const char *alg_name)
{
	struct ipcomp_tfms *pos;
	struct crypto_comp * __percpu *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 <[email protected]>");
Commit	Line	Data
6fccab67 HX	1	/*
	2	* IP Payload Compression Protocol (IPComp) - RFC3173.
	3	*
	4	* Copyright (c) 2003 James Morris <[email protected]>
	5	* Copyright (c) 2003-2008 Herbert Xu <[email protected]>
	6	*
	7	* This program is free software; you can redistribute it and/or modify it
	8	* under the terms of the GNU General Public License as published by the Free
	9	* Software Foundation; either version 2 of the License, or (at your option)
	10	* any later version.
	11	*
	12	* Todo:
	13	* - Tunable compression parameters.
	14	* - Compression stats.
	15	* - Adaptive compression.
	16	*/
	17
	18	#include <linux/crypto.h>
	19	#include <linux/err.h>
	20	#include <linux/list.h>
	21	#include <linux/module.h>
	22	#include <linux/mutex.h>
	23	#include <linux/percpu.h>
5a0e3ad6	24	#include <linux/slab.h>
6fccab67 HX	25	#include <linux/smp.h>
	26	#include <linux/vmalloc.h>
	27	#include <net/ip.h>
	28	#include <net/ipcomp.h>
	29	#include <net/xfrm.h>
	30
	31	struct ipcomp_tfms {
	32	struct list_head list;
7d720c3e	33	struct crypto_comp * __percpu *tfms;
6fccab67 HX	34	int users;
	35	};
	36
	37	static DEFINE_MUTEX(ipcomp_resource_mutex);
7d720c3e	38	static void * __percpu *ipcomp_scratches;
6fccab67 HX	39	static int ipcomp_scratch_users;
	40	static LIST_HEAD(ipcomp_tfms_list);
	41
	42	static int ipcomp_decompress(struct xfrm_state x, struct sk_buff skb)
	43	{
	44	struct ipcomp_data *ipcd = x->data;
	45	const int plen = skb->len;
	46	int dlen = IPCOMP_SCRATCH_SIZE;
	47	const u8 *start = skb->data;
	48	const int cpu = get_cpu();
	49	u8 scratch = per_cpu_ptr(ipcomp_scratches, cpu);
	50	struct crypto_comp tfm = per_cpu_ptr(ipcd->tfms, cpu);
	51	int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
7d7e5a60	52	int len;
6fccab67 HX	53
	54	if (err)
	55	goto out;
	56
	57	if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
	58	err = -EINVAL;
	59	goto out;
	60	}
	61
7d7e5a60 HX	62	len = dlen - plen;
	63	if (len > skb_tailroom(skb))
	64	len = skb_tailroom(skb);
	65
7d7e5a60 HX	66	__skb_put(skb, len);
	67
	68	len += plen;
	69	skb_copy_to_linear_data(skb, scratch, len);
	70
	71	while ((scratch += len, dlen -= len) > 0) {
	72	skb_frag_t *frag;
	73
	74	err = -EMSGSIZE;
	75	if (WARN_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS))
	76	goto out;
	77
	78	frag = skb_shinfo(skb)->frags + skb_shinfo(skb)->nr_frags;
	79	frag->page = alloc_page(GFP_ATOMIC);
	80
	81	err = -ENOMEM;
	82	if (!frag->page)
	83	goto out;
	84
	85	len = PAGE_SIZE;
	86	if (dlen < len)
	87	len = dlen;
	88
	89	memcpy(page_address(frag->page), scratch, len);
	90
	91	frag->page_offset = 0;
	92	frag->size = len;
	93	skb->truesize += len;
	94	skb->data_len += len;
	95	skb->len += len;
	96
	97	skb_shinfo(skb)->nr_frags++;
	98	}
	99
	100	err = 0;
6fccab67	101
6fccab67 HX	102	out:
	103	put_cpu();
	104	return err;
	105	}
	106
	107	int ipcomp_input(struct xfrm_state x, struct sk_buff skb)
	108	{
	109	int nexthdr;
	110	int err = -ENOMEM;
	111	struct ip_comp_hdr *ipch;
	112
	113	if (skb_linearize_cow(skb))
	114	goto out;
	115
	116	skb->ip_summed = CHECKSUM_NONE;
	117
	118	/* Remove ipcomp header and decompress original payload */
	119	ipch = (void *)skb->data;
	120	nexthdr = ipch->nexthdr;
	121
	122	skb->transport_header = skb->network_header + sizeof(*ipch);
	123	__skb_pull(skb, sizeof(*ipch));
	124	err = ipcomp_decompress(x, skb);
	125	if (err)
	126	goto out;
	127
	128	err = nexthdr;
	129
	130	out:
	131	return err;
	132	}
	133	EXPORT_SYMBOL_GPL(ipcomp_input);
	134
	135	static int ipcomp_compress(struct xfrm_state x, struct sk_buff skb)
	136	{
	137	struct ipcomp_data *ipcd = x->data;
	138	const int plen = skb->len;
	139	int dlen = IPCOMP_SCRATCH_SIZE;
	140	u8 *start = skb->data;
	141	const int cpu = get_cpu();
	142	u8 scratch = per_cpu_ptr(ipcomp_scratches, cpu);
	143	struct crypto_comp tfm = per_cpu_ptr(ipcd->tfms, cpu);
	144	int err;
	145
	146	local_bh_disable();
	147	err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
	148	local_bh_enable();
	149	if (err)
	150	goto out;
	151
	152	if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
	153	err = -EMSGSIZE;
	154	goto out;
	155	}
	156
	157	memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
	158	put_cpu();
	159
	160	pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
	161	return 0;
	162
	163	out:
	164	put_cpu();
	165	return err;
166	}
167
168	int ipcomp_output(struct xfrm_state x, struct sk_buff skb)
169	{
170	int err;
171	struct ip_comp_hdr *ipch;
172	struct ipcomp_data *ipcd = x->data;
173
174	if (skb->len < ipcd->threshold) {
175	/* Don't bother compressing */
176	goto out_ok;
177	}
178
179	if (skb_linearize_cow(skb))
180	goto out_ok;
181
182	err = ipcomp_compress(x, skb);
183
184	if (err) {
185	goto out_ok;
186	}
187
188	/* Install ipcomp header, convert into ipcomp datagram. */
189	ipch = ip_comp_hdr(skb);
190	ipch->nexthdr = *skb_mac_header(skb);
191	ipch->flags = 0;
192	ipch->cpi = htons((u16 )ntohl(x->id.spi));
193	*skb_mac_header(skb) = IPPROTO_COMP;
194	out_ok:
195	skb_push(skb, -skb_network_offset(skb));
196	return 0;
197	}
198	EXPORT_SYMBOL_GPL(ipcomp_output);
199
200	static void ipcomp_free_scratches(void)
201	{
202	int i;
7d720c3e	203	void * __percpu *scratches;
6fccab67 HX	204
	205	if (--ipcomp_scratch_users)
	206	return;
	207
	208	scratches = ipcomp_scratches;
	209	if (!scratches)
	210	return;
	211
	212	for_each_possible_cpu(i)
	213	vfree(*per_cpu_ptr(scratches, i));
	214
	215	free_percpu(scratches);
	216	}
	217
7d720c3e	218	static void * __percpu *ipcomp_alloc_scratches(void)
6fccab67 HX	219	{
6fccab67 HX	220	int i;
7d720c3e	221	void * __percpu *scratches;
6fccab67 HX	222
	223	if (ipcomp_scratch_users++)
	224	return ipcomp_scratches;
	225
	226	scratches = alloc_percpu(void *);
	227	if (!scratches)
	228	return NULL;
	229
	230	ipcomp_scratches = scratches;
	231
	232	for_each_possible_cpu(i) {
	233	void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
	234	if (!scratch)
	235	return NULL;
	236	*per_cpu_ptr(scratches, i) = scratch;
	237	}
	238
	239	return scratches;
	240	}
	241
7d720c3e	242	static void ipcomp_free_tfms(struct crypto_comp * __percpu *tfms)
6fccab67 HX	243	{
	244	struct ipcomp_tfms *pos;
	245	int cpu;
	246
	247	list_for_each_entry(pos, &ipcomp_tfms_list, list) {
	248	if (pos->tfms == tfms)
	249	break;
	250	}
	251
547b792c	252	WARN_ON(!pos);
6fccab67 HX	253
	254	if (--pos->users)
	255	return;
	256
	257	list_del(&pos->list);
	258	kfree(pos);
	259
	260	if (!tfms)
	261	return;
	262
	263	for_each_possible_cpu(cpu) {
	264	struct crypto_comp tfm = per_cpu_ptr(tfms, cpu);
	265	crypto_free_comp(tfm);
	266	}
	267	free_percpu(tfms);
	268	}
	269
7d720c3e	270	static struct crypto_comp * __percpu ipcomp_alloc_tfms(const char alg_name)
6fccab67 HX	271	{
6fccab67 HX	272	struct ipcomp_tfms *pos;
7d720c3e	273	struct crypto_comp * __percpu *tfms;
6fccab67 HX	274	int cpu;
	275
	276	/* This can be any valid CPU ID so we don't need locking. */
	277	cpu = raw_smp_processor_id();
	278
	279	list_for_each_entry(pos, &ipcomp_tfms_list, list) {
	280	struct crypto_comp *tfm;
	281
	282	tfms = pos->tfms;
	283	tfm = *per_cpu_ptr(tfms, cpu);
	284
	285	if (!strcmp(crypto_comp_name(tfm), alg_name)) {
	286	pos->users++;
	287	return tfms;
	288	}
	289	}
	290
	291	pos = kmalloc(sizeof(*pos), GFP_KERNEL);
	292	if (!pos)
	293	return NULL;
	294
	295	pos->users = 1;
	296	INIT_LIST_HEAD(&pos->list);
	297	list_add(&pos->list, &ipcomp_tfms_list);
	298
	299	pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
	300	if (!tfms)
	301	goto error;
	302
	303	for_each_possible_cpu(cpu) {
	304	struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
	305	CRYPTO_ALG_ASYNC);
	306	if (IS_ERR(tfm))
	307	goto error;
	308	*per_cpu_ptr(tfms, cpu) = tfm;
	309	}
	310
	311	return tfms;
	312
	313	error:
	314	ipcomp_free_tfms(tfms);
	315	return NULL;
	316	}
	317
	318	static void ipcomp_free_data(struct ipcomp_data *ipcd)
	319	{
	320	if (ipcd->tfms)
	321	ipcomp_free_tfms(ipcd->tfms);
	322	ipcomp_free_scratches();
	323	}
	324
	325	void ipcomp_destroy(struct xfrm_state *x)
	326	{
	327	struct ipcomp_data *ipcd = x->data;
	328	if (!ipcd)
	329	return;
	330	xfrm_state_delete_tunnel(x);
	331	mutex_lock(&ipcomp_resource_mutex);
	332	ipcomp_free_data(ipcd);
	333	mutex_unlock(&ipcomp_resource_mutex);
	334	kfree(ipcd);
	335	}
	336	EXPORT_SYMBOL_GPL(ipcomp_destroy);
	337
338	int ipcomp_init_state(struct xfrm_state *x)
339	{
340	int err;
341	struct ipcomp_data *ipcd;
342	struct xfrm_algo_desc *calg_desc;
343
344	err = -EINVAL;
345	if (!x->calg)
346	goto out;
347
348	if (x->encap)
349	goto out;
350
351	err = -ENOMEM;
352	ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
353	if (!ipcd)
354	goto out;
355
356	mutex_lock(&ipcomp_resource_mutex);
357	if (!ipcomp_alloc_scratches())
358	goto error;
359
360	ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
361	if (!ipcd->tfms)
362	goto error;
363	mutex_unlock(&ipcomp_resource_mutex);
364
365	calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
366	BUG_ON(!calg_desc);
367	ipcd->threshold = calg_desc->uinfo.comp.threshold;
368	x->data = ipcd;
369	err = 0;
370	out:
371	return err;
372
373	error:
374	ipcomp_free_data(ipcd);
375	mutex_unlock(&ipcomp_resource_mutex);
376	kfree(ipcd);
377	goto out;
378	}
379	EXPORT_SYMBOL_GPL(ipcomp_init_state);
380
381	MODULE_LICENSE("GPL");
382	MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
383	MODULE_AUTHOR("James Morris <[email protected]>");