net/xfrm/xfrm_ipcomp.c

   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/gfp.h>
  21 #include <linux/list.h>
  22 #include <linux/module.h>
  23 #include <linux/mutex.h>
  24 #include <linux/percpu.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
  31 struct ipcomp_tfms {
  32         struct list_head list;
  33         struct crypto_comp **tfms;
  34         int users;
  35 };
  36
  37 static DEFINE_MUTEX(ipcomp_resource_mutex);
  38 static void **ipcomp_scratches;
  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);
  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->truesize += len;
  67         __skb_put(skb, len);
  68
  69         len += plen;
  70         skb_copy_to_linear_data(skb, scratch, len);
  71
  72         while ((scratch += len, dlen -= len) > 0) {
  73                 skb_frag_t *frag;
  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                 frag->page = alloc_page(GFP_ATOMIC);
  81
  82                 err = -ENOMEM;
  83                 if (!frag->page)
  84                         goto out;
  85
  86                 len = PAGE_SIZE;
  87                 if (dlen < len)
  88                         len = dlen;
  89
  90                 memcpy(page_address(frag->page), scratch, len);
  91
  92                 frag->page_offset = 0;
  93                 frag->size = len;
  94                 skb->truesize += len;
  95                 skb->data_len += len;
  96                 skb->len += len;
  97
  98                 skb_shinfo(skb)->nr_frags++;
  99         }
 100
 101         err = 0;
 102
 103 out:
 104         put_cpu();
 105         return err;
 106 }
 107
 108 int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
 109 {
 110         int nexthdr;
 111         int err = -ENOMEM;
 112         struct ip_comp_hdr *ipch;
 113
 114         if (skb_linearize_cow(skb))
 115                 goto out;
 116
 117         skb->ip_summed = CHECKSUM_NONE;
 118
 119         /* Remove ipcomp header and decompress original payload */
 120         ipch = (void *)skb->data;
 121         nexthdr = ipch->nexthdr;
 122
 123         skb->transport_header = skb->network_header + sizeof(*ipch);
 124         __skb_pull(skb, sizeof(*ipch));
 125         err = ipcomp_decompress(x, skb);
 126         if (err)
 127                 goto out;
 128
 129         err = nexthdr;
 130
 131 out:
 132         return err;
 133 }
 134 EXPORT_SYMBOL_GPL(ipcomp_input);
 135
 136 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
 137 {
 138         struct ipcomp_data *ipcd = x->data;
 139         const int plen = skb->len;
 140         int dlen = IPCOMP_SCRATCH_SIZE;
 141         u8 *start = skb->data;
 142         const int cpu = get_cpu();
 143         u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
 144         struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 145         int err;
 146
 147         local_bh_disable();
 148         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 149         local_bh_enable();
 150         if (err)
 151                 goto out;
 152
 153         if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
 154                 err = -EMSGSIZE;
 155                 goto out;
 156         }
 157
 158         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 159         put_cpu();
 160
 161         pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
 162         return 0;
 163
 164 out:
 165         put_cpu();
 166         return err;
 167 }
 168
 169 int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
 170 {
 171         int err;
 172         struct ip_comp_hdr *ipch;
 173         struct ipcomp_data *ipcd = x->data;
 174
 175         if (skb->len < ipcd->threshold) {
 176                 /* Don't bother compressing */
 177                 goto out_ok;
 178         }
 179
 180         if (skb_linearize_cow(skb))
 181                 goto out_ok;
 182
 183         err = ipcomp_compress(x, skb);
 184
 185         if (err) {
 186                 goto out_ok;
 187         }
 188
 189         /* Install ipcomp header, convert into ipcomp datagram. */
 190         ipch = ip_comp_hdr(skb);
 191         ipch->nexthdr = *skb_mac_header(skb);
 192         ipch->flags = 0;
 193         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 194         *skb_mac_header(skb) = IPPROTO_COMP;
 195 out_ok:
 196         skb_push(skb, -skb_network_offset(skb));
 197         return 0;
 198 }
 199 EXPORT_SYMBOL_GPL(ipcomp_output);
 200
 201 static void ipcomp_free_scratches(void)
 202 {
 203         int i;
 204         void **scratches;
 205
 206         if (--ipcomp_scratch_users)
 207                 return;
 208
 209         scratches = ipcomp_scratches;
 210         if (!scratches)
 211                 return;
 212
 213         for_each_possible_cpu(i)
 214                 vfree(*per_cpu_ptr(scratches, i));
 215
 216         free_percpu(scratches);
 217 }
 218
 219 static void **ipcomp_alloc_scratches(void)
 220 {
 221         int i;
 222         void **scratches;
 223
 224         if (ipcomp_scratch_users++)
 225                 return ipcomp_scratches;
 226
 227         scratches = alloc_percpu(void *);
 228         if (!scratches)
 229                 return NULL;
 230
 231         ipcomp_scratches = scratches;
 232
 233         for_each_possible_cpu(i) {
 234                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
 235                 if (!scratch)
 236                         return NULL;
 237                 *per_cpu_ptr(scratches, i) = scratch;
 238         }
 239
 240         return scratches;
 241 }
 242
 243 static void ipcomp_free_tfms(struct crypto_comp **tfms)
 244 {
 245         struct ipcomp_tfms *pos;
 246         int cpu;
 247
 248         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
 249                 if (pos->tfms == tfms)
 250                         break;
 251         }
 252
 253         WARN_ON(!pos);
 254
 255         if (--pos->users)
 256                 return;
 257
 258         list_del(&pos->list);
 259         kfree(pos);
 260
 261         if (!tfms)
 262                 return;
 263
 264         for_each_possible_cpu(cpu) {
 265                 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
 266                 crypto_free_comp(tfm);
 267         }
 268         free_percpu(tfms);
 269 }
 270
 271 static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name)
 272 {
 273         struct ipcomp_tfms *pos;
 274         struct crypto_comp **tfms;
 275         int cpu;
 276
 277         /* This can be any valid CPU ID so we don't need locking. */
 278         cpu = raw_smp_processor_id();
 279
 280         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
 281                 struct crypto_comp *tfm;
 282
 283                 tfms = pos->tfms;
 284                 tfm = *per_cpu_ptr(tfms, cpu);
 285
 286                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
 287                         pos->users++;
 288                         return tfms;
 289                 }
 290         }
 291
 292         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 293         if (!pos)
 294                 return NULL;
 295
 296         pos->users = 1;
 297         INIT_LIST_HEAD(&pos->list);
 298         list_add(&pos->list, &ipcomp_tfms_list);
 299
 300         pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
 301         if (!tfms)
 302                 goto error;
 303
 304         for_each_possible_cpu(cpu) {
 305                 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
 306                                                             CRYPTO_ALG_ASYNC);
 307                 if (IS_ERR(tfm))
 308                         goto error;
 309                 *per_cpu_ptr(tfms, cpu) = tfm;
 310         }
 311
 312         return tfms;
 313
 314 error:
 315         ipcomp_free_tfms(tfms);
 316         return NULL;
 317 }
 318
 319 static void ipcomp_free_data(struct ipcomp_data *ipcd)
 320 {
 321         if (ipcd->tfms)
 322                 ipcomp_free_tfms(ipcd->tfms);
 323         ipcomp_free_scratches();
 324 }
 325
 326 void ipcomp_destroy(struct xfrm_state *x)
 327 {
 328         struct ipcomp_data *ipcd = x->data;
 329         if (!ipcd)
 330                 return;
 331         xfrm_state_delete_tunnel(x);
 332         mutex_lock(&ipcomp_resource_mutex);
 333         ipcomp_free_data(ipcd);
 334         mutex_unlock(&ipcomp_resource_mutex);
 335         kfree(ipcd);
 336 }
 337 EXPORT_SYMBOL_GPL(ipcomp_destroy);
 338
 339 int ipcomp_init_state(struct xfrm_state *x)
 340 {
 341         int err;
 342         struct ipcomp_data *ipcd;
 343         struct xfrm_algo_desc *calg_desc;
 344
 345         err = -EINVAL;
 346         if (!x->calg)
 347                 goto out;
 348
 349         if (x->encap)
 350                 goto out;
 351
 352         err = -ENOMEM;
 353         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
 354         if (!ipcd)
 355                 goto out;
 356
 357         mutex_lock(&ipcomp_resource_mutex);
 358         if (!ipcomp_alloc_scratches())
 359                 goto error;
 360
 361         ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
 362         if (!ipcd->tfms)
 363                 goto error;
 364         mutex_unlock(&ipcomp_resource_mutex);
 365
 366         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
 367         BUG_ON(!calg_desc);
 368         ipcd->threshold = calg_desc->uinfo.comp.threshold;
 369         x->data = ipcd;
 370         err = 0;
 371 out:
 372         return err;
 373
 374 error:
 375         ipcomp_free_data(ipcd);
 376         mutex_unlock(&ipcomp_resource_mutex);
 377         kfree(ipcd);
 378         goto out;
 379 }
 380 EXPORT_SYMBOL_GPL(ipcomp_init_state);
 381
 382 MODULE_LICENSE("GPL");
 383 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
 384 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");