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/config.h>
  17 #include <linux/module.h>
  18 #include <asm/scatterlist.h>
  19 #include <asm/semaphore.h>
  20 #include <linux/crypto.h>
  21 #include <linux/pfkeyv2.h>
  22 #include <linux/percpu.h>
  23 #include <linux/smp.h>
  24 #include <linux/list.h>
  25 #include <linux/vmalloc.h>
  26 #include <linux/rtnetlink.h>
  27 #include <linux/mutex.h>
  28 #include <net/ip.h>
  29 #include <net/xfrm.h>
  30 #include <net/icmp.h>
  31 #include <net/ipcomp.h>
  32 #include <net/protocol.h>
  33
  34 struct ipcomp_tfms {
  35         struct list_head list;
  36         struct crypto_tfm **tfms;
  37         int users;
  38 };
  39
  40 static DEFINE_MUTEX(ipcomp_resource_mutex);
  41 static void **ipcomp_scratches;
  42 static int ipcomp_scratch_users;
  43 static LIST_HEAD(ipcomp_tfms_list);
  44
  45 static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
  46 {
  47         int err, plen, dlen;
  48         struct iphdr *iph;
  49         struct ipcomp_data *ipcd = x->data;
  50         u8 *start, *scratch;
  51         struct crypto_tfm *tfm;
  52         int cpu;
  53
  54         plen = skb->len;
  55         dlen = IPCOMP_SCRATCH_SIZE;
  56         start = skb->data;
  57
  58         cpu = get_cpu();
  59         scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
  60         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
  61
  62         err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
  63         if (err)
  64                 goto out;
  65
  66         if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
  67                 err = -EINVAL;
  68                 goto out;
  69         }
  70
  71         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
  72         if (err)
  73                 goto out;
  74
  75         skb_put(skb, dlen - plen);
  76         memcpy(skb->data, scratch, dlen);
  77         iph = skb->nh.iph;
  78         iph->tot_len = htons(dlen + iph->ihl * 4);
  79 out:
  80         put_cpu();
  81         return err;
  82 }
  83
  84 static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
  85 {
  86         u8 nexthdr;
  87         int err = 0;
  88         struct iphdr *iph;
  89         union {
  90                 struct iphdr    iph;
  91                 char            buf[60];
  92         } tmp_iph;
  93
  94
  95         if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
  96             skb_linearize(skb, GFP_ATOMIC) != 0) {
  97                 err = -ENOMEM;
  98                 goto out;
  99         }
 100
 101         skb->ip_summed = CHECKSUM_NONE;
 102
 103         /* Remove ipcomp header and decompress original payload */
 104         iph = skb->nh.iph;
 105         memcpy(&tmp_iph, iph, iph->ihl * 4);
 106         nexthdr = *(u8 *)skb->data;
 107         skb_pull(skb, sizeof(struct ip_comp_hdr));
 108         skb->nh.raw += sizeof(struct ip_comp_hdr);
 109         memcpy(skb->nh.raw, &tmp_iph, tmp_iph.iph.ihl * 4);
 110         iph = skb->nh.iph;
 111         iph->tot_len = htons(ntohs(iph->tot_len) - sizeof(struct ip_comp_hdr));
 112         iph->protocol = nexthdr;
 113         skb->h.raw = skb->data;
 114         err = ipcomp_decompress(x, skb);
 115
 116 out:
 117         return err;
 118 }
 119
 120 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
 121 {
 122         int err, plen, dlen, ihlen;
 123         struct iphdr *iph = skb->nh.iph;
 124         struct ipcomp_data *ipcd = x->data;
 125         u8 *start, *scratch;
 126         struct crypto_tfm *tfm;
 127         int cpu;
 128
 129         ihlen = iph->ihl * 4;
 130         plen = skb->len - ihlen;
 131         dlen = IPCOMP_SCRATCH_SIZE;
 132         start = skb->data + ihlen;
 133
 134         cpu = get_cpu();
 135         scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
 136         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 137
 138         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
 139         if (err)
 140                 goto out;
 141
 142         if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
 143                 err = -EMSGSIZE;
 144                 goto out;
 145         }
 146
 147         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
 148         put_cpu();
 149
 150         pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr));
 151         return 0;
 152
 153 out:
 154         put_cpu();
 155         return err;
 156 }
 157
 158 static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
 159 {
 160         int err;
 161         struct iphdr *iph;
 162         struct ip_comp_hdr *ipch;
 163         struct ipcomp_data *ipcd = x->data;
 164         int hdr_len = 0;
 165
 166         iph = skb->nh.iph;
 167         iph->tot_len = htons(skb->len);
 168         hdr_len = iph->ihl * 4;
 169         if ((skb->len - hdr_len) < ipcd->threshold) {
 170                 /* Don't bother compressing */
 171                 goto out_ok;
 172         }
 173
 174         if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
 175             skb_linearize(skb, GFP_ATOMIC) != 0) {
 176                 goto out_ok;
 177         }
 178
 179         err = ipcomp_compress(x, skb);
 180         iph = skb->nh.iph;
 181
 182         if (err) {
 183                 goto out_ok;
 184         }
 185
 186         /* Install ipcomp header, convert into ipcomp datagram. */
 187         iph->tot_len = htons(skb->len);
 188         ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4);
 189         ipch->nexthdr = iph->protocol;
 190         ipch->flags = 0;
 191         ipch->cpi = htons((u16 )ntohl(x->id.spi));
 192         iph->protocol = IPPROTO_COMP;
 193         ip_send_check(iph);
 194         return 0;
 195
 196 out_ok:
 197         if (x->props.mode)
 198                 ip_send_check(iph);
 199         return 0;
 200 }
 201
 202 static void ipcomp4_err(struct sk_buff *skb, u32 info)
 203 {
 204         u32 spi;
 205         struct iphdr *iph = (struct iphdr *)skb->data;
 206         struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
 207         struct xfrm_state *x;
 208
 209         if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
 210             skb->h.icmph->code != ICMP_FRAG_NEEDED)
 211                 return;
 212
 213         spi = ntohl(ntohs(ipch->cpi));
 214         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
 215                               spi, IPPROTO_COMP, AF_INET);
 216         if (!x)
 217                 return;
 218         NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n",
 219                  spi, NIPQUAD(iph->daddr));
 220         xfrm_state_put(x);
 221 }
 222
 223 /* We always hold one tunnel user reference to indicate a tunnel */
 224 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
 225 {
 226         struct xfrm_state *t;
 227
 228         t = xfrm_state_alloc();
 229         if (t == NULL)
 230                 goto out;
 231
 232         t->id.proto = IPPROTO_IPIP;
 233         t->id.spi = x->props.saddr.a4;
 234         t->id.daddr.a4 = x->id.daddr.a4;
 235         memcpy(&t->sel, &x->sel, sizeof(t->sel));
 236         t->props.family = AF_INET;
 237         t->props.mode = 1;
 238         t->props.saddr.a4 = x->props.saddr.a4;
 239         t->props.flags = x->props.flags;
 240
 241         if (xfrm_init_state(t))
 242                 goto error;
 243
 244         atomic_set(&t->tunnel_users, 1);
 245 out:
 246         return t;
 247
 248 error:
 249         t->km.state = XFRM_STATE_DEAD;
 250         xfrm_state_put(t);
 251         t = NULL;
 252         goto out;
 253 }
 254
 255 /*
 256  * Must be protected by xfrm_cfg_mutex.  State and tunnel user references are
 257  * always incremented on success.
 258  */
 259 static int ipcomp_tunnel_attach(struct xfrm_state *x)
 260 {
 261         int err = 0;
 262         struct xfrm_state *t;
 263
 264         t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
 265                               x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
 266         if (!t) {
 267                 t = ipcomp_tunnel_create(x);
 268                 if (!t) {
 269                         err = -EINVAL;
 270                         goto out;
 271                 }
 272                 xfrm_state_insert(t);
 273                 xfrm_state_hold(t);
 274         }
 275         x->tunnel = t;
 276         atomic_inc(&t->tunnel_users);
 277 out:
 278         return err;
 279 }
 280
 281 static void ipcomp_free_scratches(void)
 282 {
 283         int i;
 284         void **scratches;
 285
 286         if (--ipcomp_scratch_users)
 287                 return;
 288
 289         scratches = ipcomp_scratches;
 290         if (!scratches)
 291                 return;
 292
 293         for_each_possible_cpu(i)
 294                 vfree(*per_cpu_ptr(scratches, i));
 295
 296         free_percpu(scratches);
 297 }
 298
 299 static void **ipcomp_alloc_scratches(void)
 300 {
 301         int i;
 302         void **scratches;
 303
 304         if (ipcomp_scratch_users++)
 305                 return ipcomp_scratches;
 306
 307         scratches = alloc_percpu(void *);
 308         if (!scratches)
 309                 return NULL;
 310
 311         ipcomp_scratches = scratches;
 312
 313         for_each_possible_cpu(i) {
 314                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
 315                 if (!scratch)
 316                         return NULL;
 317                 *per_cpu_ptr(scratches, i) = scratch;
 318         }
 319
 320         return scratches;
 321 }
 322
 323 static void ipcomp_free_tfms(struct crypto_tfm **tfms)
 324 {
 325         struct ipcomp_tfms *pos;
 326         int cpu;
 327
 328         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
 329                 if (pos->tfms == tfms)
 330                         break;
 331         }
 332
 333         BUG_TRAP(pos);
 334
 335         if (--pos->users)
 336                 return;
 337
 338         list_del(&pos->list);
 339         kfree(pos);
 340
 341         if (!tfms)
 342                 return;
 343
 344         for_each_possible_cpu(cpu) {
 345                 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu);
 346                 crypto_free_tfm(tfm);
 347         }
 348         free_percpu(tfms);
 349 }
 350
 351 static struct crypto_tfm **ipcomp_alloc_tfms(const char *alg_name)
 352 {
 353         struct ipcomp_tfms *pos;
 354         struct crypto_tfm **tfms;
 355         int cpu;
 356
 357         /* This can be any valid CPU ID so we don't need locking. */
 358         cpu = raw_smp_processor_id();
 359
 360         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
 361                 struct crypto_tfm *tfm;
 362
 363                 tfms = pos->tfms;
 364                 tfm = *per_cpu_ptr(tfms, cpu);
 365
 366                 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) {
 367                         pos->users++;
 368                         return tfms;
 369                 }
 370         }
 371
 372         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
 373         if (!pos)
 374                 return NULL;
 375
 376         pos->users = 1;
 377         INIT_LIST_HEAD(&pos->list);
 378         list_add(&pos->list, &ipcomp_tfms_list);
 379
 380         pos->tfms = tfms = alloc_percpu(struct crypto_tfm *);
 381         if (!tfms)
 382                 goto error;
 383
 384         for_each_possible_cpu(cpu) {
 385                 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0);
 386                 if (!tfm)
 387                         goto error;
 388                 *per_cpu_ptr(tfms, cpu) = tfm;
 389         }
 390
 391         return tfms;
 392
 393 error:
 394         ipcomp_free_tfms(tfms);
 395         return NULL;
 396 }
 397
 398 static void ipcomp_free_data(struct ipcomp_data *ipcd)
 399 {
 400         if (ipcd->tfms)
 401                 ipcomp_free_tfms(ipcd->tfms);
 402         ipcomp_free_scratches();
 403 }
 404
 405 static void ipcomp_destroy(struct xfrm_state *x)
 406 {
 407         struct ipcomp_data *ipcd = x->data;
 408         if (!ipcd)
 409                 return;
 410         xfrm_state_delete_tunnel(x);
 411         mutex_lock(&ipcomp_resource_mutex);
 412         ipcomp_free_data(ipcd);
 413         mutex_unlock(&ipcomp_resource_mutex);
 414         kfree(ipcd);
 415 }
 416
 417 static int ipcomp_init_state(struct xfrm_state *x)
 418 {
 419         int err;
 420         struct ipcomp_data *ipcd;
 421         struct xfrm_algo_desc *calg_desc;
 422
 423         err = -EINVAL;
 424         if (!x->calg)
 425                 goto out;
 426
 427         if (x->encap)
 428                 goto out;
 429
 430         err = -ENOMEM;
 431         ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL);
 432         if (!ipcd)
 433                 goto out;
 434
 435         memset(ipcd, 0, sizeof(*ipcd));
 436         x->props.header_len = 0;
 437         if (x->props.mode)
 438                 x->props.header_len += sizeof(struct iphdr);
 439
 440         mutex_lock(&ipcomp_resource_mutex);
 441         if (!ipcomp_alloc_scratches())
 442                 goto error;
 443
 444         ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
 445         if (!ipcd->tfms)
 446                 goto error;
 447         mutex_unlock(&ipcomp_resource_mutex);
 448
 449         if (x->props.mode) {
 450                 err = ipcomp_tunnel_attach(x);
 451                 if (err)
 452                         goto error_tunnel;
 453         }
 454
 455         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
 456         BUG_ON(!calg_desc);
 457         ipcd->threshold = calg_desc->uinfo.comp.threshold;
 458         x->data = ipcd;
 459         err = 0;
 460 out:
 461         return err;
 462
 463 error_tunnel:
 464         mutex_lock(&ipcomp_resource_mutex);
 465 error:
 466         ipcomp_free_data(ipcd);
 467         mutex_unlock(&ipcomp_resource_mutex);
 468         kfree(ipcd);
 469         goto out;
 470 }
 471
 472 static struct xfrm_type ipcomp_type = {
 473         .description    = "IPCOMP4",
 474         .owner          = THIS_MODULE,
 475         .proto          = IPPROTO_COMP,
 476         .init_state     = ipcomp_init_state,
 477         .destructor     = ipcomp_destroy,
 478         .input          = ipcomp_input,
 479         .output         = ipcomp_output
 480 };
 481
 482 static struct net_protocol ipcomp4_protocol = {
 483         .handler        =       xfrm4_rcv,
 484         .err_handler    =       ipcomp4_err,
 485         .no_policy      =       1,
 486 };
 487
 488 static int __init ipcomp4_init(void)
 489 {
 490         if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
 491                 printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
 492                 return -EAGAIN;
 493         }
 494         if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
 495                 printk(KERN_INFO "ipcomp init: can't add protocol\n");
 496                 xfrm_unregister_type(&ipcomp_type, AF_INET);
 497                 return -EAGAIN;
 498         }
 499         return 0;
 500 }
 501
 502 static void __exit ipcomp4_fini(void)
 503 {
 504         if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
 505                 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
 506         if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
 507                 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
 508 }
 509
 510 module_init(ipcomp4_init);
 511 module_exit(ipcomp4_fini);
 512
 513 MODULE_LICENSE("GPL");
 514 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
 515 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
 516