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/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
  31 struct ipcomp_tfms {
  32         struct list_head list;
  33         struct crypto_comp * __percpu *tfms;
  34         int users;
  35 };
  36
  37 static DEFINE_MUTEX(ipcomp_resource_mutex);
  38 static void * __percpu *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                 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
 105 out:
 106         put_cpu();
 107         return err;
 108 }
 109
 110 int 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
 133 out:
 134         return err;
 135 }
 136 EXPORT_SYMBOL_GPL(ipcomp_input);
 137
 138 static 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
 166 out:
 167         put_cpu();
 168         return err;
 169 }
 170
 171 int 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;
 197 out_ok:
 198         skb_push(skb, -skb_network_offset(skb));
 199         return 0;
 200 }
 201 EXPORT_SYMBOL_GPL(ipcomp_output);
 202
 203 static 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
 221 static 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
 245 static 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
 273 static 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
 280         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
 281                 struct crypto_comp *tfm;
 282
 283                 /* This can be any valid CPU ID so we don't need locking. */
 284                 tfm = __this_cpu_read(*pos->tfms);
 285
 286                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
 287                         pos->users++;
 288                         return pos->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>");