[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;
		struct page *page;

		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;
		page = alloc_page(GFP_ATOMIC);

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

		__skb_frag_set_page(frag, page);

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

		frag->page_offset = 0;
		frag->size = len;
		memcpy(skb_frag_address(frag), scratch, 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;
804cf14e	73	struct page *page;
7d7e5a60 HX	74
	75	err = -EMSGSIZE;
	76	if (WARN_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS))
	77	goto out;
	78
	79	frag = skb_shinfo(skb)->frags + skb_shinfo(skb)->nr_frags;
804cf14e	80	page = alloc_page(GFP_ATOMIC);
7d7e5a60 HX	81
7d7e5a60 HX	82	err = -ENOMEM;
804cf14e	83	if (!page)
7d7e5a60 HX	84	goto out;
7d7e5a60 HX	85
804cf14e IC	86	__skb_frag_set_page(frag, page);
804cf14e IC	87
7d7e5a60 HX	88	len = PAGE_SIZE;
	89	if (dlen < len)
	90	len = dlen;
	91
7d7e5a60 HX	92	frag->page_offset = 0;
7d7e5a60 HX	93	frag->size = len;
804cf14e IC	94	memcpy(skb_frag_address(frag), scratch, len);
804cf14e IC	95
7d7e5a60 HX	96	skb->truesize += len;
	97	skb->data_len += len;
	98	skb->len += len;
	99
	100	skb_shinfo(skb)->nr_frags++;
	101	}
	102
	103	err = 0;
6fccab67	104
6fccab67 HX	105	out:
	106	put_cpu();
	107	return err;
	108	}
	109
	110	int ipcomp_input(struct xfrm_state x, struct sk_buff skb)
	111	{
	112	int nexthdr;
	113	int err = -ENOMEM;
	114	struct ip_comp_hdr *ipch;
	115
	116	if (skb_linearize_cow(skb))
	117	goto out;
	118
	119	skb->ip_summed = CHECKSUM_NONE;
	120
	121	/* Remove ipcomp header and decompress original payload */
	122	ipch = (void *)skb->data;
	123	nexthdr = ipch->nexthdr;
	124
	125	skb->transport_header = skb->network_header + sizeof(*ipch);
	126	__skb_pull(skb, sizeof(*ipch));
	127	err = ipcomp_decompress(x, skb);
	128	if (err)
	129	goto out;
	130
	131	err = nexthdr;
	132
	133	out:
	134	return err;
	135	}
	136	EXPORT_SYMBOL_GPL(ipcomp_input);
	137
	138	static int ipcomp_compress(struct xfrm_state x, struct sk_buff skb)
	139	{
	140	struct ipcomp_data *ipcd = x->data;
	141	const int plen = skb->len;
	142	int dlen = IPCOMP_SCRATCH_SIZE;
	143	u8 *start = skb->data;
	144	const int cpu = get_cpu();
	145	u8 scratch = per_cpu_ptr(ipcomp_scratches, cpu);
	146	struct crypto_comp tfm = per_cpu_ptr(ipcd->tfms, cpu);
	147	int err;
	148
	149	local_bh_disable();
	150	err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
	151	local_bh_enable();
	152	if (err)
	153	goto out;
	154
	155	if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
	156	err = -EMSGSIZE;
	157	goto out;
	158	}
	159
	160	memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
	161	put_cpu();
	162
	163	pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
	164	return 0;
	165
	166	out:
	167	put_cpu();
	168	return err;
169	}
170
171	int ipcomp_output(struct xfrm_state x, struct sk_buff skb)
172	{
173	int err;
174	struct ip_comp_hdr *ipch;
175	struct ipcomp_data *ipcd = x->data;
176
177	if (skb->len < ipcd->threshold) {
178	/* Don't bother compressing */
179	goto out_ok;
180	}
181
182	if (skb_linearize_cow(skb))
183	goto out_ok;
184
185	err = ipcomp_compress(x, skb);
186
187	if (err) {
188	goto out_ok;
189	}
190
191	/* Install ipcomp header, convert into ipcomp datagram. */
192	ipch = ip_comp_hdr(skb);
193	ipch->nexthdr = *skb_mac_header(skb);
194	ipch->flags = 0;
195	ipch->cpi = htons((u16 )ntohl(x->id.spi));
196	*skb_mac_header(skb) = IPPROTO_COMP;
197	out_ok:
198	skb_push(skb, -skb_network_offset(skb));
199	return 0;
200	}
201	EXPORT_SYMBOL_GPL(ipcomp_output);
202
203	static void ipcomp_free_scratches(void)
204	{
205	int i;
7d720c3e	206	void * __percpu *scratches;
6fccab67 HX	207
	208	if (--ipcomp_scratch_users)
	209	return;
	210
	211	scratches = ipcomp_scratches;
	212	if (!scratches)
	213	return;
	214
	215	for_each_possible_cpu(i)
	216	vfree(*per_cpu_ptr(scratches, i));
	217
	218	free_percpu(scratches);
	219	}
	220
7d720c3e	221	static void * __percpu *ipcomp_alloc_scratches(void)
6fccab67 HX	222	{
6fccab67 HX	223	int i;
7d720c3e	224	void * __percpu *scratches;
6fccab67 HX	225
	226	if (ipcomp_scratch_users++)
	227	return ipcomp_scratches;
	228
	229	scratches = alloc_percpu(void *);
	230	if (!scratches)
	231	return NULL;
	232
	233	ipcomp_scratches = scratches;
	234
	235	for_each_possible_cpu(i) {
	236	void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
	237	if (!scratch)
	238	return NULL;
	239	*per_cpu_ptr(scratches, i) = scratch;
	240	}
	241
	242	return scratches;
	243	}
	244
7d720c3e	245	static void ipcomp_free_tfms(struct crypto_comp * __percpu *tfms)
6fccab67 HX	246	{
	247	struct ipcomp_tfms *pos;
	248	int cpu;
	249
	250	list_for_each_entry(pos, &ipcomp_tfms_list, list) {
	251	if (pos->tfms == tfms)
	252	break;
	253	}
	254
547b792c	255	WARN_ON(!pos);
6fccab67 HX	256
	257	if (--pos->users)
	258	return;
	259
	260	list_del(&pos->list);
	261	kfree(pos);
	262
	263	if (!tfms)
	264	return;
	265
	266	for_each_possible_cpu(cpu) {
	267	struct crypto_comp tfm = per_cpu_ptr(tfms, cpu);
	268	crypto_free_comp(tfm);
	269	}
	270	free_percpu(tfms);
	271	}
	272
7d720c3e	273	static struct crypto_comp * __percpu ipcomp_alloc_tfms(const char alg_name)
6fccab67 HX	274	{
6fccab67 HX	275	struct ipcomp_tfms *pos;
7d720c3e	276	struct crypto_comp * __percpu *tfms;
6fccab67 HX	277	int cpu;
	278
	279	/* This can be any valid CPU ID so we don't need locking. */
	280	cpu = raw_smp_processor_id();
	281
	282	list_for_each_entry(pos, &ipcomp_tfms_list, list) {
	283	struct crypto_comp *tfm;
	284
	285	tfms = pos->tfms;
	286	tfm = *per_cpu_ptr(tfms, cpu);
	287
	288	if (!strcmp(crypto_comp_name(tfm), alg_name)) {
	289	pos->users++;
	290	return tfms;
	291	}
	292	}
	293
	294	pos = kmalloc(sizeof(*pos), GFP_KERNEL);
	295	if (!pos)
	296	return NULL;
	297
	298	pos->users = 1;
	299	INIT_LIST_HEAD(&pos->list);
	300	list_add(&pos->list, &ipcomp_tfms_list);
	301
	302	pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
	303	if (!tfms)
	304	goto error;
	305
	306	for_each_possible_cpu(cpu) {
	307	struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
	308	CRYPTO_ALG_ASYNC);
	309	if (IS_ERR(tfm))
	310	goto error;
	311	*per_cpu_ptr(tfms, cpu) = tfm;
	312	}
	313
	314	return tfms;
	315
	316	error:
	317	ipcomp_free_tfms(tfms);
	318	return NULL;
	319	}
	320
	321	static void ipcomp_free_data(struct ipcomp_data *ipcd)
	322	{
	323	if (ipcd->tfms)
	324	ipcomp_free_tfms(ipcd->tfms);
	325	ipcomp_free_scratches();
	326	}
	327
	328	void ipcomp_destroy(struct xfrm_state *x)
	329	{
	330	struct ipcomp_data *ipcd = x->data;
	331	if (!ipcd)
	332	return;
	333	xfrm_state_delete_tunnel(x);
	334	mutex_lock(&ipcomp_resource_mutex);
	335	ipcomp_free_data(ipcd);
	336	mutex_unlock(&ipcomp_resource_mutex);
	337	kfree(ipcd);
	338	}
	339	EXPORT_SYMBOL_GPL(ipcomp_destroy);
	340
341	int ipcomp_init_state(struct xfrm_state *x)
342	{
343	int err;
344	struct ipcomp_data *ipcd;
345	struct xfrm_algo_desc *calg_desc;
346
347	err = -EINVAL;
348	if (!x->calg)
349	goto out;
350
351	if (x->encap)
352	goto out;
353
354	err = -ENOMEM;
355	ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
356	if (!ipcd)
357	goto out;
358
359	mutex_lock(&ipcomp_resource_mutex);
360	if (!ipcomp_alloc_scratches())
361	goto error;
362
363	ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
364	if (!ipcd->tfms)
365	goto error;
366	mutex_unlock(&ipcomp_resource_mutex);
367
368	calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
369	BUG_ON(!calg_desc);
370	ipcd->threshold = calg_desc->uinfo.comp.threshold;
371	x->data = ipcd;
372	err = 0;
373	out:
374	return err;
375
376	error:
377	ipcomp_free_data(ipcd);
378	mutex_unlock(&ipcomp_resource_mutex);
379	kfree(ipcd);
380	goto out;
381	}
382	EXPORT_SYMBOL_GPL(ipcomp_init_state);
383
384	MODULE_LICENSE("GPL");
385	MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
386	MODULE_AUTHOR("James Morris <[email protected]>");