net/ipv4/ipcomp.c

   1 /*
   2  * IP Payload Compression Protocol (IPComp) - RFC3173.
   3  *
   4  * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the Free
   8  * Software Foundation; either version 2 of the License, or (at your option)
   9  * any later version.
  10  *
  11  * Todo:
  12  *   - Tunable compression parameters.
  13  *   - Compression stats.
  14  *   - Adaptive compression.
  15  */
  16 #include <linux/module.h>
  17 #include <linux/crypto.h>
  18 #include <linux/err.h>
  19 #include <linux/pfkeyv2.h>
  20 #include <linux/percpu.h>
  21 #include <linux/smp.h>
  22 #include <linux/list.h>
  23 #include <linux/vmalloc.h>
  24 #include <linux/rtnetlink.h>
  25 #include <linux/mutex.h>
  26 #include <net/ip.h>
  27 #include <net/xfrm.h>
  28 #include <net/icmp.h>
  29 #include <net/ipcomp.h>
  30 #include <net/protocol.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
  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         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
  63         if (err)
  64                 goto out;
  65
  66         skb->truesize += dlen - plen;
  67         __skb_put(skb, dlen - plen);
  68         skb_copy_to_linear_data(skb, scratch, dlen);
  69 out:
  70         put_cpu();
  71         return err;
  72 }
  73
  74 static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
  75 {
  76         int nexthdr;
  77         int err = -ENOMEM;
  78         struct ip_comp_hdr *ipch;
  79
  80         if (skb_linearize_cow(skb))
  81                 goto out;
  82
  83         skb->ip_summed = CHECKSUM_NONE;
  84
  85         /* Remove ipcomp header and decompress original payload */
  86         ipch = (void *)skb->data;
  87         nexthdr = ipch->nexthdr;
  88
  89         skb->transport_header = skb->network_header + sizeof(*ipch);
  90         __skb_pull(skb, sizeof(*ipch));
  91         err = ipcomp_decompress(x, skb);
  92         if (err)
  93                 goto out;
  94
  95         err = nexthdr;
  96
  97 out:
  98         return err;
  99 }
 100
 101 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
 102 {
 103         struct ipcomp_data *ipcd = x->data;
 104         const int plen = skb->len;
 105         int dlen = IPCOMP_SCRATCH_SIZE;
 106         u8 *start = skb->data;
 107         const int cpu = get_cpu();
 108         u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
 109         struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 110         int err;
 111
 112         local_bh_disable();
 113         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 114         local_bh_enable();
 115         if (err)
 116                 goto out;
 117
 118         if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
 119                 err = -EMSGSIZE;
 120                 goto out;
 121         }
 122
 123         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 124         put_cpu();
 125
 126         pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
 127         return 0;
 128
 129 out:
 130         put_cpu();
 131         return err;
 132 }
 133
 134 static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
 135 {
 136         int err;
 137         struct ip_comp_hdr *ipch;
 138         struct ipcomp_data *ipcd = x->data;
 139
 140         if (skb->len < ipcd->threshold) {
 141                 /* Don't bother compressing */
 142                 goto out_ok;
 143         }
 144
 145         if (skb_linearize_cow(skb))
 146                 goto out_ok;
 147
 148         err = ipcomp_compress(x, skb);
 149
 150         if (err) {
 151                 goto out_ok;
 152         }
 153
 154         /* Install ipcomp header, convert into ipcomp datagram. */
 155         ipch = ip_comp_hdr(skb);
 156         ipch->nexthdr = *skb_mac_header(skb);
 157         ipch->flags = 0;
 158         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 159         *skb_mac_header(skb) = IPPROTO_COMP;
 160 out_ok:
 161         skb_push(skb, -skb_network_offset(skb));
 162         return 0;
 163 }
 164
 165 static void ipcomp4_err(struct sk_buff *skb, u32 info)
 166 {
 167         __be32 spi;
 168         struct iphdr *iph = (struct iphdr *)skb->data;
 169         struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
 170         struct xfrm_state *x;
 171
 172         if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
 173             icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
 174                 return;
 175
 176         spi = htonl(ntohs(ipch->cpi));
 177         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
 178                               spi, IPPROTO_COMP, AF_INET);
 179         if (!x)
 180                 return;
 181         NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIPQUAD_FMT "\n",
 182                  spi, NIPQUAD(iph->daddr));
 183         xfrm_state_put(x);
 184 }
 185
 186 /* We always hold one tunnel user reference to indicate a tunnel */
 187 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
 188 {
 189         struct xfrm_state *t;
 190
 191         t = xfrm_state_alloc();
 192         if (t == NULL)
 193                 goto out;
 194
 195         t->id.proto = IPPROTO_IPIP;
 196         t->id.spi = x->props.saddr.a4;
 197         t->id.daddr.a4 = x->id.daddr.a4;
 198         memcpy(&t->sel, &x->sel, sizeof(t->sel));
 199         t->props.family = AF_INET;
 200         t->props.mode = x->props.mode;
 201         t->props.saddr.a4 = x->props.saddr.a4;
 202         t->props.flags = x->props.flags;
 203
 204         if (xfrm_init_state(t))
 205                 goto error;
 206
 207         atomic_set(&t->tunnel_users, 1);
 208 out:
 209         return t;
 210
 211 error:
 212         t->km.state = XFRM_STATE_DEAD;
 213         xfrm_state_put(t);
 214         t = NULL;
 215         goto out;
 216 }
 217
 218 /*
 219  * Must be protected by xfrm_cfg_mutex.  State and tunnel user references are
 220  * always incremented on success.
 221  */
 222 static int ipcomp_tunnel_attach(struct xfrm_state *x)
 223 {
 224         int err = 0;
 225         struct xfrm_state *t;
 226
 227         t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
 228                               x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
 229         if (!t) {
 230                 t = ipcomp_tunnel_create(x);
 231                 if (!t) {
 232                         err = -EINVAL;
 233                         goto out;
 234                 }
 235                 xfrm_state_insert(t);
 236                 xfrm_state_hold(t);
 237         }
 238         x->tunnel = t;
 239         atomic_inc(&t->tunnel_users);
 240 out:
 241         return err;
 242 }
 243
 244 static void ipcomp_free_scratches(void)
 245 {
 246         int i;
 247         void **scratches;
 248
 249         if (--ipcomp_scratch_users)
 250                 return;
 251
 252         scratches = ipcomp_scratches;
 253         if (!scratches)
 254                 return;
 255
 256         for_each_possible_cpu(i)
 257                 vfree(*per_cpu_ptr(scratches, i));
 258
 259         free_percpu(scratches);
 260 }
 261
 262 static void **ipcomp_alloc_scratches(void)
 263 {
 264         int i;
 265         void **scratches;
 266
 267         if (ipcomp_scratch_users++)
 268                 return ipcomp_scratches;
 269
 270         scratches = alloc_percpu(void *);
 271         if (!scratches)
 272                 return NULL;
 273
 274         ipcomp_scratches = scratches;
 275
 276         for_each_possible_cpu(i) {
 277                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
 278                 if (!scratch)
 279                         return NULL;
 280                 *per_cpu_ptr(scratches, i) = scratch;
 281         }
 282
 283         return scratches;
 284 }
 285
 286 static void ipcomp_free_tfms(struct crypto_comp **tfms)
 287 {
 288         struct ipcomp_tfms *pos;
 289         int cpu;
 290
 291         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
 292                 if (pos->tfms == tfms)
 293                         break;
 294         }
 295
 296         BUG_TRAP(pos);
 297
 298         if (--pos->users)
 299                 return;
 300
 301         list_del(&pos->list);
 302         kfree(pos);
 303
 304         if (!tfms)
 305                 return;
 306
 307         for_each_possible_cpu(cpu) {
 308                 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
 309                 crypto_free_comp(tfm);
 310         }
 311         free_percpu(tfms);
 312 }
 313
 314 static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name)
 315 {
 316         struct ipcomp_tfms *pos;
 317         struct crypto_comp **tfms;
 318         int cpu;
 319
 320         /* This can be any valid CPU ID so we don't need locking. */
 321         cpu = raw_smp_processor_id();
 322
 323         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
 324                 struct crypto_comp *tfm;
 325
 326                 tfms = pos->tfms;
 327                 tfm = *per_cpu_ptr(tfms, cpu);
 328
 329                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
 330                         pos->users++;
 331                         return tfms;
 332                 }
 333         }
 334
 335         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 336         if (!pos)
 337                 return NULL;
 338
 339         pos->users = 1;
 340         INIT_LIST_HEAD(&pos->list);
 341         list_add(&pos->list, &ipcomp_tfms_list);
 342
 343         pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
 344         if (!tfms)
 345                 goto error;
 346
 347         for_each_possible_cpu(cpu) {
 348                 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
 349                                                             CRYPTO_ALG_ASYNC);
 350                 if (IS_ERR(tfm))
 351                         goto error;
 352                 *per_cpu_ptr(tfms, cpu) = tfm;
 353         }
 354
 355         return tfms;
 356
 357 error:
 358         ipcomp_free_tfms(tfms);
 359         return NULL;
 360 }
 361
 362 static void ipcomp_free_data(struct ipcomp_data *ipcd)
 363 {
 364         if (ipcd->tfms)
 365                 ipcomp_free_tfms(ipcd->tfms);
 366         ipcomp_free_scratches();
 367 }
 368
 369 static void ipcomp_destroy(struct xfrm_state *x)
 370 {
 371         struct ipcomp_data *ipcd = x->data;
 372         if (!ipcd)
 373                 return;
 374         xfrm_state_delete_tunnel(x);
 375         mutex_lock(&ipcomp_resource_mutex);
 376         ipcomp_free_data(ipcd);
 377         mutex_unlock(&ipcomp_resource_mutex);
 378         kfree(ipcd);
 379 }
 380
 381 static int ipcomp_init_state(struct xfrm_state *x)
 382 {
 383         int err;
 384         struct ipcomp_data *ipcd;
 385         struct xfrm_algo_desc *calg_desc;
 386
 387         err = -EINVAL;
 388         if (!x->calg)
 389                 goto out;
 390
 391         if (x->encap)
 392                 goto out;
 393
 394         x->props.header_len = 0;
 395         switch (x->props.mode) {
 396         case XFRM_MODE_TRANSPORT:
 397                 break;
 398         case XFRM_MODE_TUNNEL:
 399                 x->props.header_len += sizeof(struct iphdr);
 400                 break;
 401         default:
 402                 goto out;
 403         }
 404
 405         err = -ENOMEM;
 406         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
 407         if (!ipcd)
 408                 goto out;
 409
 410         mutex_lock(&ipcomp_resource_mutex);
 411         if (!ipcomp_alloc_scratches())
 412                 goto error;
 413
 414         ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
 415         if (!ipcd->tfms)
 416                 goto error;
 417         mutex_unlock(&ipcomp_resource_mutex);
 418
 419         if (x->props.mode == XFRM_MODE_TUNNEL) {
 420                 err = ipcomp_tunnel_attach(x);
 421                 if (err)
 422                         goto error_tunnel;
 423         }
 424
 425         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
 426         BUG_ON(!calg_desc);
 427         ipcd->threshold = calg_desc->uinfo.comp.threshold;
 428         x->data = ipcd;
 429         err = 0;
 430 out:
 431         return err;
 432
 433 error_tunnel:
 434         mutex_lock(&ipcomp_resource_mutex);
 435 error:
 436         ipcomp_free_data(ipcd);
 437         mutex_unlock(&ipcomp_resource_mutex);
 438         kfree(ipcd);
 439         goto out;
 440 }
 441
 442 static const struct xfrm_type ipcomp_type = {
 443         .description    = "IPCOMP4",
 444         .owner          = THIS_MODULE,
 445         .proto          = IPPROTO_COMP,
 446         .init_state     = ipcomp_init_state,
 447         .destructor     = ipcomp_destroy,
 448         .input          = ipcomp_input,
 449         .output         = ipcomp_output
 450 };
 451
 452 static struct net_protocol ipcomp4_protocol = {
 453         .handler        =       xfrm4_rcv,
 454         .err_handler    =       ipcomp4_err,
 455         .no_policy      =       1,
 456 };
 457
 458 static int __init ipcomp4_init(void)
 459 {
 460         if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
 461                 printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
 462                 return -EAGAIN;
 463         }
 464         if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
 465                 printk(KERN_INFO "ipcomp init: can't add protocol\n");
 466                 xfrm_unregister_type(&ipcomp_type, AF_INET);
 467                 return -EAGAIN;
 468         }
 469         return 0;
 470 }
 471
 472 static void __exit ipcomp4_fini(void)
 473 {
 474         if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
 475                 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
 476         if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
 477                 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
 478 }
 479
 480 module_init(ipcomp4_init);
 481 module_exit(ipcomp4_fini);
 482
 483 MODULE_LICENSE("GPL");
 484 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
 485 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
 486
 487 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP);