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 <asm/semaphore.h>
  18 #include <linux/crypto.h>
  19 #include <linux/err.h>
  20 #include <linux/pfkeyv2.h>
  21 #include <linux/percpu.h>
  22 #include <linux/smp.h>
  23 #include <linux/list.h>
  24 #include <linux/vmalloc.h>
  25 #include <linux/rtnetlink.h>
  26 #include <linux/mutex.h>
  27 #include <net/ip.h>
  28 #include <net/xfrm.h>
  29 #include <net/icmp.h>
  30 #include <net/ipcomp.h>
  31 #include <net/protocol.h>
  32
  33 struct ipcomp_tfms {
  34         struct list_head list;
  35         struct crypto_comp **tfms;
  36         int users;
  37 };
  38
  39 static DEFINE_MUTEX(ipcomp_resource_mutex);
  40 static void **ipcomp_scratches;
  41 static int ipcomp_scratch_users;
  42 static LIST_HEAD(ipcomp_tfms_list);
  43
  44 static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
  45 {
  46         struct ipcomp_data *ipcd = x->data;
  47         const int plen = skb->len;
  48         int dlen = IPCOMP_SCRATCH_SIZE;
  49         const u8 *start = skb->data;
  50         const int cpu = get_cpu();
  51         u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
  52         struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
  53         int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
  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         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
  64         if (err)
  65                 goto out;
  66
  67         skb->truesize += dlen - plen;
  68         __skb_put(skb, dlen - plen);
  69         skb_copy_to_linear_data(skb, scratch, dlen);
  70 out:
  71         put_cpu();
  72         return err;
  73 }
  74
  75 static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
  76 {
  77         int nexthdr;
  78         int err = -ENOMEM;
  79         struct ip_comp_hdr *ipch;
  80
  81         if (skb_linearize_cow(skb))
  82                 goto out;
  83
  84         skb->ip_summed = CHECKSUM_NONE;
  85
  86         /* Remove ipcomp header and decompress original payload */
  87         ipch = (void *)skb->data;
  88         nexthdr = ipch->nexthdr;
  89
  90         skb->transport_header = skb->network_header + sizeof(*ipch);
  91         __skb_pull(skb, sizeof(*ipch));
  92         err = ipcomp_decompress(x, skb);
  93         if (err)
  94                 goto out;
  95
  96         err = nexthdr;
  97
  98 out:
  99         return err;
 100 }
 101
 102 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
 103 {
 104         struct ipcomp_data *ipcd = x->data;
 105         const int plen = skb->len;
 106         int dlen = IPCOMP_SCRATCH_SIZE;
 107         u8 *start = skb->data;
 108         const int cpu = get_cpu();
 109         u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
 110         struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 111         int err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 112
 113         if (err)
 114                 goto out;
 115
 116         if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
 117                 err = -EMSGSIZE;
 118                 goto out;
 119         }
 120
 121         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 122         put_cpu();
 123
 124         pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
 125         return 0;
 126
 127 out:
 128         put_cpu();
 129         return err;
 130 }
 131
 132 static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
 133 {
 134         int err;
 135         struct ip_comp_hdr *ipch;
 136         struct ipcomp_data *ipcd = x->data;
 137
 138         if (skb->len < ipcd->threshold) {
 139                 /* Don't bother compressing */
 140                 goto out_ok;
 141         }
 142
 143         if (skb_linearize_cow(skb))
 144                 goto out_ok;
 145
 146         err = ipcomp_compress(x, skb);
 147
 148         if (err) {
 149                 goto out_ok;
 150         }
 151
 152         /* Install ipcomp header, convert into ipcomp datagram. */
 153         ipch = ip_comp_hdr(skb);
 154         ipch->nexthdr = *skb_mac_header(skb);
 155         ipch->flags = 0;
 156         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 157         *skb_mac_header(skb) = IPPROTO_COMP;
 158 out_ok:
 159         skb_push(skb, -skb_network_offset(skb));
 160         return 0;
 161 }
 162
 163 static void ipcomp4_err(struct sk_buff *skb, u32 info)
 164 {
 165         __be32 spi;
 166         struct iphdr *iph = (struct iphdr *)skb->data;
 167         struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
 168         struct xfrm_state *x;
 169
 170         if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
 171             icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
 172                 return;
 173
 174         spi = htonl(ntohs(ipch->cpi));
 175         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
 176                               spi, IPPROTO_COMP, AF_INET);
 177         if (!x)
 178                 return;
 179         NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n",
 180                  spi, NIPQUAD(iph->daddr));
 181         xfrm_state_put(x);
 182 }
 183
 184 /* We always hold one tunnel user reference to indicate a tunnel */
 185 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
 186 {
 187         struct xfrm_state *t;
 188
 189         t = xfrm_state_alloc();
 190         if (t == NULL)
 191                 goto out;
 192
 193         t->id.proto = IPPROTO_IPIP;
 194         t->id.spi = x->props.saddr.a4;
 195         t->id.daddr.a4 = x->id.daddr.a4;
 196         memcpy(&t->sel, &x->sel, sizeof(t->sel));
 197         t->props.family = AF_INET;
 198         t->props.mode = x->props.mode;
 199         t->props.saddr.a4 = x->props.saddr.a4;
 200         t->props.flags = x->props.flags;
 201
 202         if (xfrm_init_state(t))
 203                 goto error;
 204
 205         atomic_set(&t->tunnel_users, 1);
 206 out:
 207         return t;
 208
 209 error:
 210         t->km.state = XFRM_STATE_DEAD;
 211         xfrm_state_put(t);
 212         t = NULL;
 213         goto out;
 214 }
 215
 216 /*
 217  * Must be protected by xfrm_cfg_mutex.  State and tunnel user references are
 218  * always incremented on success.
 219  */
 220 static int ipcomp_tunnel_attach(struct xfrm_state *x)
 221 {
 222         int err = 0;
 223         struct xfrm_state *t;
 224
 225         t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
 226                               x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
 227         if (!t) {
 228                 t = ipcomp_tunnel_create(x);
 229                 if (!t) {
 230                         err = -EINVAL;
 231                         goto out;
 232                 }
 233                 xfrm_state_insert(t);
 234                 xfrm_state_hold(t);
 235         }
 236         x->tunnel = t;
 237         atomic_inc(&t->tunnel_users);
 238 out:
 239         return err;
 240 }
 241
 242 static void ipcomp_free_scratches(void)
 243 {
 244         int i;
 245         void **scratches;
 246
 247         if (--ipcomp_scratch_users)
 248                 return;
 249
 250         scratches = ipcomp_scratches;
 251         if (!scratches)
 252                 return;
 253
 254         for_each_possible_cpu(i)
 255                 vfree(*per_cpu_ptr(scratches, i));
 256
 257         free_percpu(scratches);
 258 }
 259
 260 static void **ipcomp_alloc_scratches(void)
 261 {
 262         int i;
 263         void **scratches;
 264
 265         if (ipcomp_scratch_users++)
 266                 return ipcomp_scratches;
 267
 268         scratches = alloc_percpu(void *);
 269         if (!scratches)
 270                 return NULL;
 271
 272         ipcomp_scratches = scratches;
 273
 274         for_each_possible_cpu(i) {
 275                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
 276                 if (!scratch)
 277                         return NULL;
 278                 *per_cpu_ptr(scratches, i) = scratch;
 279         }
 280
 281         return scratches;
 282 }
 283
 284 static void ipcomp_free_tfms(struct crypto_comp **tfms)
 285 {
 286         struct ipcomp_tfms *pos;
 287         int cpu;
 288
 289         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
 290                 if (pos->tfms == tfms)
 291                         break;
 292         }
 293
 294         BUG_TRAP(pos);
 295
 296         if (--pos->users)
 297                 return;
 298
 299         list_del(&pos->list);
 300         kfree(pos);
 301
 302         if (!tfms)
 303                 return;
 304
 305         for_each_possible_cpu(cpu) {
 306                 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
 307                 crypto_free_comp(tfm);
 308         }
 309         free_percpu(tfms);
 310 }
 311
 312 static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name)
 313 {
 314         struct ipcomp_tfms *pos;
 315         struct crypto_comp **tfms;
 316         int cpu;
 317
 318         /* This can be any valid CPU ID so we don't need locking. */
 319         cpu = raw_smp_processor_id();
 320
 321         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
 322                 struct crypto_comp *tfm;
 323
 324                 tfms = pos->tfms;
 325                 tfm = *per_cpu_ptr(tfms, cpu);
 326
 327                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
 328                         pos->users++;
 329                         return tfms;
 330                 }
 331         }
 332
 333         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 334         if (!pos)
 335                 return NULL;
 336
 337         pos->users = 1;
 338         INIT_LIST_HEAD(&pos->list);
 339         list_add(&pos->list, &ipcomp_tfms_list);
 340
 341         pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
 342         if (!tfms)
 343                 goto error;
 344
 345         for_each_possible_cpu(cpu) {
 346                 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
 347                                                             CRYPTO_ALG_ASYNC);
 348                 if (IS_ERR(tfm))
 349                         goto error;
 350                 *per_cpu_ptr(tfms, cpu) = tfm;
 351         }
 352
 353         return tfms;
 354
 355 error:
 356         ipcomp_free_tfms(tfms);
 357         return NULL;
 358 }
 359
 360 static void ipcomp_free_data(struct ipcomp_data *ipcd)
 361 {
 362         if (ipcd->tfms)
 363                 ipcomp_free_tfms(ipcd->tfms);
 364         ipcomp_free_scratches();
 365 }
 366
 367 static void ipcomp_destroy(struct xfrm_state *x)
 368 {
 369         struct ipcomp_data *ipcd = x->data;
 370         if (!ipcd)
 371                 return;
 372         xfrm_state_delete_tunnel(x);
 373         mutex_lock(&ipcomp_resource_mutex);
 374         ipcomp_free_data(ipcd);
 375         mutex_unlock(&ipcomp_resource_mutex);
 376         kfree(ipcd);
 377 }
 378
 379 static int ipcomp_init_state(struct xfrm_state *x)
 380 {
 381         int err;
 382         struct ipcomp_data *ipcd;
 383         struct xfrm_algo_desc *calg_desc;
 384
 385         err = -EINVAL;
 386         if (!x->calg)
 387                 goto out;
 388
 389         if (x->encap)
 390                 goto out;
 391
 392         x->props.header_len = 0;
 393         switch (x->props.mode) {
 394         case XFRM_MODE_TRANSPORT:
 395                 break;
 396         case XFRM_MODE_TUNNEL:
 397                 x->props.header_len += sizeof(struct iphdr);
 398                 break;
 399         default:
 400                 goto out;
 401         }
 402
 403         err = -ENOMEM;
 404         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
 405         if (!ipcd)
 406                 goto out;
 407
 408         mutex_lock(&ipcomp_resource_mutex);
 409         if (!ipcomp_alloc_scratches())
 410                 goto error;
 411
 412         ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
 413         if (!ipcd->tfms)
 414                 goto error;
 415         mutex_unlock(&ipcomp_resource_mutex);
 416
 417         if (x->props.mode == XFRM_MODE_TUNNEL) {
 418                 err = ipcomp_tunnel_attach(x);
 419                 if (err)
 420                         goto error_tunnel;
 421         }
 422
 423         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
 424         BUG_ON(!calg_desc);
 425         ipcd->threshold = calg_desc->uinfo.comp.threshold;
 426         x->data = ipcd;
 427         err = 0;
 428 out:
 429         return err;
 430
 431 error_tunnel:
 432         mutex_lock(&ipcomp_resource_mutex);
 433 error:
 434         ipcomp_free_data(ipcd);
 435         mutex_unlock(&ipcomp_resource_mutex);
 436         kfree(ipcd);
 437         goto out;
 438 }
 439
 440 static const struct xfrm_type ipcomp_type = {
 441         .description    = "IPCOMP4",
 442         .owner          = THIS_MODULE,
 443         .proto          = IPPROTO_COMP,
 444         .init_state     = ipcomp_init_state,
 445         .destructor     = ipcomp_destroy,
 446         .input          = ipcomp_input,
 447         .output         = ipcomp_output
 448 };
 449
 450 static struct net_protocol ipcomp4_protocol = {
 451         .handler        =       xfrm4_rcv,
 452         .err_handler    =       ipcomp4_err,
 453         .no_policy      =       1,
 454 };
 455
 456 static int __init ipcomp4_init(void)
 457 {
 458         if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
 459                 printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
 460                 return -EAGAIN;
 461         }
 462         if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
 463                 printk(KERN_INFO "ipcomp init: can't add protocol\n");
 464                 xfrm_unregister_type(&ipcomp_type, AF_INET);
 465                 return -EAGAIN;
 466         }
 467         return 0;
 468 }
 469
 470 static void __exit ipcomp4_fini(void)
 471 {
 472         if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
 473                 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
 474         if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
 475                 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
 476 }
 477
 478 module_init(ipcomp4_init);
 479 module_exit(ipcomp4_fini);
 480
 481 MODULE_LICENSE("GPL");
 482 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
 483 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
 484
 485 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP);