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/rtnetlink.h>
  26 #include <linux/smp.h>
  27 #include <linux/vmalloc.h>
  28 #include <net/ip.h>
  29 #include <net/ipcomp.h>
  30 #include <net/xfrm.h>
  31
  32 struct ipcomp_tfms {
  33         struct list_head list;
  34         struct crypto_comp **tfms;
  35         int users;
  36 };
  37
  38 static DEFINE_MUTEX(ipcomp_resource_mutex);
  39 static void **ipcomp_scratches;
  40 static int ipcomp_scratch_users;
  41 static LIST_HEAD(ipcomp_tfms_list);
  42
  43 static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
  44 {
  45         struct ipcomp_data *ipcd = x->data;
  46         const int plen = skb->len;
  47         int dlen = IPCOMP_SCRATCH_SIZE;
  48         const u8 *start = skb->data;
  49         const int cpu = get_cpu();
  50         u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
  51         struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
  52         int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
  53         int len;
  54
  55         if (err)
  56                 goto out;
  57
  58         if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
  59                 err = -EINVAL;
  60                 goto out;
  61         }
  62
  63         len = dlen - plen;
  64         if (len > skb_tailroom(skb))
  65                 len = skb_tailroom(skb);
  66
  67         skb->truesize += len;
  68         __skb_put(skb, len);
  69
  70         len += plen;
  71         skb_copy_to_linear_data(skb, scratch, len);
  72
  73         while ((scratch += len, dlen -= len) > 0) {
  74                 skb_frag_t *frag;
  75
  76                 err = -EMSGSIZE;
  77                 if (WARN_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS))
  78                         goto out;
  79
  80                 frag = skb_shinfo(skb)->frags + skb_shinfo(skb)->nr_frags;
  81                 frag->page = alloc_page(GFP_ATOMIC);
  82
  83                 err = -ENOMEM;
  84                 if (!frag->page)
  85                         goto out;
  86
  87                 len = PAGE_SIZE;
  88                 if (dlen < len)
  89                         len = dlen;
  90
  91                 memcpy(page_address(frag->page), scratch, len);
  92
  93                 frag->page_offset = 0;
  94                 frag->size = len;
  95                 skb->truesize += len;
  96                 skb->data_len += len;
  97                 skb->len += len;
  98
  99                 skb_shinfo(skb)->nr_frags++;
 100         }
 101
 102         err = 0;
 103
 104 out:
 105         put_cpu();
 106         return err;
 107 }
 108
 109 int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
 110 {
 111         int nexthdr;
 112         int err = -ENOMEM;
 113         struct ip_comp_hdr *ipch;
 114
 115         if (skb_linearize_cow(skb))
 116                 goto out;
 117
 118         skb->ip_summed = CHECKSUM_NONE;
 119
 120         /* Remove ipcomp header and decompress original payload */
 121         ipch = (void *)skb->data;
 122         nexthdr = ipch->nexthdr;
 123
 124         skb->transport_header = skb->network_header + sizeof(*ipch);
 125         __skb_pull(skb, sizeof(*ipch));
 126         err = ipcomp_decompress(x, skb);
 127         if (err)
 128                 goto out;
 129
 130         err = nexthdr;
 131
 132 out:
 133         return err;
 134 }
 135 EXPORT_SYMBOL_GPL(ipcomp_input);
 136
 137 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
 138 {
 139         struct ipcomp_data *ipcd = x->data;
 140         const int plen = skb->len;
 141         int dlen = IPCOMP_SCRATCH_SIZE;
 142         u8 *start = skb->data;
 143         const int cpu = get_cpu();
 144         u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
 145         struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 146         int err;
 147
 148         local_bh_disable();
 149         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 150         local_bh_enable();
 151         if (err)
 152                 goto out;
 153
 154         if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
 155                 err = -EMSGSIZE;
 156                 goto out;
 157         }
 158
 159         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 160         put_cpu();
 161
 162         pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
 163         return 0;
 164
 165 out:
 166         put_cpu();
 167         return err;
 168 }
 169
 170 int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
 171 {
 172         int err;
 173         struct ip_comp_hdr *ipch;
 174         struct ipcomp_data *ipcd = x->data;
 175
 176         if (skb->len < ipcd->threshold) {
 177                 /* Don't bother compressing */
 178                 goto out_ok;
 179         }
 180
 181         if (skb_linearize_cow(skb))
 182                 goto out_ok;
 183
 184         err = ipcomp_compress(x, skb);
 185
 186         if (err) {
 187                 goto out_ok;
 188         }
 189
 190         /* Install ipcomp header, convert into ipcomp datagram. */
 191         ipch = ip_comp_hdr(skb);
 192         ipch->nexthdr = *skb_mac_header(skb);
 193         ipch->flags = 0;
 194         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 195         *skb_mac_header(skb) = IPPROTO_COMP;
 196 out_ok:
 197         skb_push(skb, -skb_network_offset(skb));
 198         return 0;
 199 }
 200 EXPORT_SYMBOL_GPL(ipcomp_output);
 201
 202 static void ipcomp_free_scratches(void)
 203 {
 204         int i;
 205         void **scratches;
 206
 207         if (--ipcomp_scratch_users)
 208                 return;
 209
 210         scratches = ipcomp_scratches;
 211         if (!scratches)
 212                 return;
 213
 214         for_each_possible_cpu(i)
 215                 vfree(*per_cpu_ptr(scratches, i));
 216
 217         free_percpu(scratches);
 218 }
 219
 220 static void **ipcomp_alloc_scratches(void)
 221 {
 222         int i;
 223         void **scratches;
 224
 225         if (ipcomp_scratch_users++)
 226                 return ipcomp_scratches;
 227
 228         scratches = alloc_percpu(void *);
 229         if (!scratches)
 230                 return NULL;
 231
 232         ipcomp_scratches = scratches;
 233
 234         for_each_possible_cpu(i) {
 235                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
 236                 if (!scratch)
 237                         return NULL;
 238                 *per_cpu_ptr(scratches, i) = scratch;
 239         }
 240
 241         return scratches;
 242 }
 243
 244 static void ipcomp_free_tfms(struct crypto_comp **tfms)
 245 {
 246         struct ipcomp_tfms *pos;
 247         int cpu;
 248
 249         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
 250                 if (pos->tfms == tfms)
 251                         break;
 252         }
 253
 254         BUG_TRAP(pos);
 255
 256         if (--pos->users)
 257                 return;
 258
 259         list_del(&pos->list);
 260         kfree(pos);
 261
 262         if (!tfms)
 263                 return;
 264
 265         for_each_possible_cpu(cpu) {
 266                 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
 267                 crypto_free_comp(tfm);
 268         }
 269         free_percpu(tfms);
 270 }
 271
 272 static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name)
 273 {
 274         struct ipcomp_tfms *pos;
 275         struct crypto_comp **tfms;
 276         int cpu;
 277
 278         /* This can be any valid CPU ID so we don't need locking. */
 279         cpu = raw_smp_processor_id();
 280
 281         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
 282                 struct crypto_comp *tfm;
 283
 284                 tfms = pos->tfms;
 285                 tfm = *per_cpu_ptr(tfms, cpu);
 286
 287                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
 288                         pos->users++;
 289                         return tfms;
 290                 }
 291         }
 292
 293         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 294         if (!pos)
 295                 return NULL;
 296
 297         pos->users = 1;
 298         INIT_LIST_HEAD(&pos->list);
 299         list_add(&pos->list, &ipcomp_tfms_list);
 300
 301         pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
 302         if (!tfms)
 303                 goto error;
 304
 305         for_each_possible_cpu(cpu) {
 306                 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
 307                                                             CRYPTO_ALG_ASYNC);
 308                 if (IS_ERR(tfm))
 309                         goto error;
 310                 *per_cpu_ptr(tfms, cpu) = tfm;
 311         }
 312
 313         return tfms;
 314
 315 error:
 316         ipcomp_free_tfms(tfms);
 317         return NULL;
 318 }
 319
 320 static void ipcomp_free_data(struct ipcomp_data *ipcd)
 321 {
 322         if (ipcd->tfms)
 323                 ipcomp_free_tfms(ipcd->tfms);
 324         ipcomp_free_scratches();
 325 }
 326
 327 void ipcomp_destroy(struct xfrm_state *x)
 328 {
 329         struct ipcomp_data *ipcd = x->data;
 330         if (!ipcd)
 331                 return;
 332         xfrm_state_delete_tunnel(x);
 333         mutex_lock(&ipcomp_resource_mutex);
 334         ipcomp_free_data(ipcd);
 335         mutex_unlock(&ipcomp_resource_mutex);
 336         kfree(ipcd);
 337 }
 338 EXPORT_SYMBOL_GPL(ipcomp_destroy);
 339
 340 int ipcomp_init_state(struct xfrm_state *x)
 341 {
 342         int err;
 343         struct ipcomp_data *ipcd;
 344         struct xfrm_algo_desc *calg_desc;
 345
 346         err = -EINVAL;
 347         if (!x->calg)
 348                 goto out;
 349
 350         if (x->encap)
 351                 goto out;
 352
 353         err = -ENOMEM;
 354         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
 355         if (!ipcd)
 356                 goto out;
 357
 358         mutex_lock(&ipcomp_resource_mutex);
 359         if (!ipcomp_alloc_scratches())
 360                 goto error;
 361
 362         ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
 363         if (!ipcd->tfms)
 364                 goto error;
 365         mutex_unlock(&ipcomp_resource_mutex);
 366
 367         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
 368         BUG_ON(!calg_desc);
 369         ipcd->threshold = calg_desc->uinfo.comp.threshold;
 370         x->data = ipcd;
 371         err = 0;
 372 out:
 373         return err;
 374
 375 error:
 376         ipcomp_free_data(ipcd);
 377         mutex_unlock(&ipcomp_resource_mutex);
 378         kfree(ipcd);
 379         goto out;
 380 }
 381 EXPORT_SYMBOL_GPL(ipcomp_init_state);
 382
 383 MODULE_LICENSE("GPL");
 384 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
 385 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");