linux-imx

/*

 * 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/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))