linux/net/xfrm/xfrm_ipcomp.c
<<
>>
Prefs
   1/*
   2 * IP Payload Compression Protocol (IPComp) - RFC3173.
   3 *
   4 * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
   5 * Copyright (c) 2003-2008 Herbert Xu <herbert@gondor.apana.org.au>
   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>
  24#include <linux/slab.h>
  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
  31struct ipcomp_tfms {
  32        struct list_head list;
  33        struct crypto_comp * __percpu *tfms;
  34        int users;
  35};
  36
  37static DEFINE_MUTEX(ipcomp_resource_mutex);
  38static void * __percpu *ipcomp_scratches;
  39static int ipcomp_scratch_users;
  40static LIST_HEAD(ipcomp_tfms_list);
  41
  42static 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);
  52        int len;
  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
  62        len = dlen - plen;
  63        if (len > skb_tailroom(skb))
  64                len = skb_tailroom(skb);
  65
  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                struct page *page;
  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;
  80                page = alloc_page(GFP_ATOMIC);
  81
  82                err = -ENOMEM;
  83                if (!page)
  84                        goto out;
  85
  86                __skb_frag_set_page(frag, page);
  87
  88                len = PAGE_SIZE;
  89                if (dlen < len)
  90                        len = dlen;
  91
  92                frag->page_offset = 0;
  93                skb_frag_size_set(frag, len);
  94                memcpy(skb_frag_address(frag), scratch, len);
  95
  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;
 104
 105out:
 106        put_cpu();
 107        return err;
 108}
 109
 110int 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
 133out:
 134        return err;
 135}
 136EXPORT_SYMBOL_GPL(ipcomp_input);
 137
 138static 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
 166out:
 167        put_cpu();
 168        return err;
 169}
 170
 171int 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;
 197out_ok:
 198        skb_push(skb, -skb_network_offset(skb));
 199        return 0;
 200}
 201EXPORT_SYMBOL_GPL(ipcomp_output);
 202
 203static void ipcomp_free_scratches(void)
 204{
 205        int i;
 206        void * __percpu *scratches;
 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
 221static void * __percpu *ipcomp_alloc_scratches(void)
 222{
 223        int i;
 224        void * __percpu *scratches;
 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
 245static void ipcomp_free_tfms(struct crypto_comp * __percpu *tfms)
 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
 255        WARN_ON(!pos);
 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
 273static struct crypto_comp * __percpu *ipcomp_alloc_tfms(const char *alg_name)
 274{
 275        struct ipcomp_tfms *pos;
 276        struct crypto_comp * __percpu *tfms;
 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
 316error:
 317        ipcomp_free_tfms(tfms);
 318        return NULL;
 319}
 320
 321static 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
 328void 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}
 339EXPORT_SYMBOL_GPL(ipcomp_destroy);
 340
 341int 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;
 373out:
 374        return err;
 375
 376error:
 377        ipcomp_free_data(ipcd);
 378        mutex_unlock(&ipcomp_resource_mutex);
 379        kfree(ipcd);
 380        goto out;
 381}
 382EXPORT_SYMBOL_GPL(ipcomp_init_state);
 383
 384MODULE_LICENSE("GPL");
 385MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
 386MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
 387
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.