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_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;
 101
 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;
 203         void **scratches;
 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
 218 static void **ipcomp_alloc_scratches(void)
 219 {
 220         int i;
 221         void **scratches;
 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
 242 static void ipcomp_free_tfms(struct crypto_comp **tfms)
 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
 252         WARN_ON(!pos);
 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
 270 static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name)
 271 {
 272         struct ipcomp_tfms *pos;
 273         struct crypto_comp **tfms;
 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 <jmorris@intercode.com.au>");