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