net/batman-adv/unicast.c

   1 /* Copyright (C) 2010-2013 B.A.T.M.A.N. contributors:
   2  *
   3  * Andreas Langer
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of version 2 of the GNU General Public
   7  * License as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  17  * 02110-1301, USA
  18  */
  19
  20 #include "main.h"
  21 #include "unicast.h"
  22 #include "send.h"
  23 #include "soft-interface.h"
  24 #include "gateway_client.h"
  25 #include "originator.h"
  26 #include "hash.h"
  27 #include "translation-table.h"
  28 #include "routing.h"
  29 #include "hard-interface.h"
  30
  31
  32 static struct sk_buff *
  33 batadv_frag_merge_packet(struct list_head *head,
  34                          struct batadv_frag_packet_list_entry *tfp,
  35                          struct sk_buff *skb)
  36 {
  37         struct batadv_unicast_frag_packet *up;
  38         struct sk_buff *tmp_skb;
  39         struct batadv_unicast_packet *unicast_packet;
  40         int hdr_len = sizeof(*unicast_packet);
  41         int uni_diff = sizeof(*up) - hdr_len;
  42         uint8_t *packet_pos;
  43
  44         up = (struct batadv_unicast_frag_packet *)skb->data;
  45         /* set skb to the first part and tmp_skb to the second part */
  46         if (up->flags & BATADV_UNI_FRAG_HEAD) {
  47                 tmp_skb = tfp->skb;
  48         } else {
  49                 tmp_skb = skb;
  50                 skb = tfp->skb;
  51         }
  52
  53         if (skb_linearize(skb) < 0 || skb_linearize(tmp_skb) < 0)
  54                 goto err;
  55
  56         skb_pull(tmp_skb, sizeof(*up));
  57         if (pskb_expand_head(skb, 0, tmp_skb->len, GFP_ATOMIC) < 0)
  58                 goto err;
  59
  60         /* move free entry to end */
  61         tfp->skb = NULL;
  62         tfp->seqno = 0;
  63         list_move_tail(&tfp->list, head);
  64
  65         memcpy(skb_put(skb, tmp_skb->len), tmp_skb->data, tmp_skb->len);
  66         kfree_skb(tmp_skb);
  67
  68         memmove(skb->data + uni_diff, skb->data, hdr_len);
  69         packet_pos = skb_pull(skb, uni_diff);
  70         unicast_packet = (struct batadv_unicast_packet *)packet_pos;
  71         unicast_packet->header.packet_type = BATADV_UNICAST;
  72
  73         return skb;
  74
  75 err:
  76         /* free buffered skb, skb will be freed later */
  77         kfree_skb(tfp->skb);
  78         return NULL;
  79 }
  80
  81 static void batadv_frag_create_entry(struct list_head *head,
  82                                      struct sk_buff *skb)
  83 {
  84         struct batadv_frag_packet_list_entry *tfp;
  85         struct batadv_unicast_frag_packet *up;
  86
  87         up = (struct batadv_unicast_frag_packet *)skb->data;
  88
  89         /* free and oldest packets stand at the end */
  90         tfp = list_entry((head)->prev, typeof(*tfp), list);
  91         kfree_skb(tfp->skb);
  92
  93         tfp->seqno = ntohs(up->seqno);
  94         tfp->skb = skb;
  95         list_move(&tfp->list, head);
  96         return;
  97 }
  98
  99 static int batadv_frag_create_buffer(struct list_head *head)
 100 {
 101         int i;
 102         struct batadv_frag_packet_list_entry *tfp;
 103
 104         for (i = 0; i < BATADV_FRAG_BUFFER_SIZE; i++) {
 105                 tfp = kmalloc(sizeof(*tfp), GFP_ATOMIC);
 106                 if (!tfp) {
 107                         batadv_frag_list_free(head);
 108                         return -ENOMEM;
 109                 }
 110                 tfp->skb = NULL;
 111                 tfp->seqno = 0;
 112                 INIT_LIST_HEAD(&tfp->list);
 113                 list_add(&tfp->list, head);
 114         }
 115
 116         return 0;
 117 }
 118
 119 static struct batadv_frag_packet_list_entry *
 120 batadv_frag_search_packet(struct list_head *head,
 121                           const struct batadv_unicast_frag_packet *up)
 122 {
 123         struct batadv_frag_packet_list_entry *tfp;
 124         struct batadv_unicast_frag_packet *tmp_up = NULL;
 125         bool is_head_tmp, is_head;
 126         uint16_t search_seqno;
 127
 128         if (up->flags & BATADV_UNI_FRAG_HEAD)
 129                 search_seqno = ntohs(up->seqno)+1;
 130         else
 131                 search_seqno = ntohs(up->seqno)-1;
 132
 133         is_head = up->flags & BATADV_UNI_FRAG_HEAD;
 134
 135         list_for_each_entry(tfp, head, list) {
 136                 if (!tfp->skb)
 137                         continue;
 138
 139                 if (tfp->seqno == ntohs(up->seqno))
 140                         goto mov_tail;
 141
 142                 tmp_up = (struct batadv_unicast_frag_packet *)tfp->skb->data;
 143
 144                 if (tfp->seqno == search_seqno) {
 145                         is_head_tmp = tmp_up->flags & BATADV_UNI_FRAG_HEAD;
 146                         if (is_head_tmp != is_head)
 147                                 return tfp;
 148                         else
 149                                 goto mov_tail;
 150                 }
 151         }
 152         return NULL;
 153
 154 mov_tail:
 155         list_move_tail(&tfp->list, head);
 156         return NULL;
 157 }
 158
 159 void batadv_frag_list_free(struct list_head *head)
 160 {
 161         struct batadv_frag_packet_list_entry *pf, *tmp_pf;
 162
 163         if (!list_empty(head)) {
 164                 list_for_each_entry_safe(pf, tmp_pf, head, list) {
 165                         kfree_skb(pf->skb);
 166                         list_del(&pf->list);
 167                         kfree(pf);
 168                 }
 169         }
 170         return;
 171 }
 172
 173 /* frag_reassemble_skb():
 174  * returns NET_RX_DROP if the operation failed - skb is left intact
 175  * returns NET_RX_SUCCESS if the fragment was buffered (skb_new will be NULL)
 176  * or the skb could be reassembled (skb_new will point to the new packet and
 177  * skb was freed)
 178  */
 179 int batadv_frag_reassemble_skb(struct sk_buff *skb,
 180                                struct batadv_priv *bat_priv,
 181                                struct sk_buff **new_skb)
 182 {
 183         struct batadv_orig_node *orig_node;
 184         struct batadv_frag_packet_list_entry *tmp_frag_entry;
 185         int ret = NET_RX_DROP;
 186         struct batadv_unicast_frag_packet *unicast_packet;
 187
 188         unicast_packet = (struct batadv_unicast_frag_packet *)skb->data;
 189         *new_skb = NULL;
 190
 191         orig_node = batadv_orig_hash_find(bat_priv, unicast_packet->orig);
 192         if (!orig_node)
 193                 goto out;
 194
 195         orig_node->last_frag_packet = jiffies;
 196
 197         if (list_empty(&orig_node->frag_list) &&
 198             batadv_frag_create_buffer(&orig_node->frag_list)) {
 199                 pr_debug("couldn't create frag buffer\n");
 200                 goto out;
 201         }
 202
 203         tmp_frag_entry = batadv_frag_search_packet(&orig_node->frag_list,
 204                                                    unicast_packet);
 205
 206         if (!tmp_frag_entry) {
 207                 batadv_frag_create_entry(&orig_node->frag_list, skb);
 208                 ret = NET_RX_SUCCESS;
 209                 goto out;
 210         }
 211
 212         *new_skb = batadv_frag_merge_packet(&orig_node->frag_list,
 213                                             tmp_frag_entry, skb);
 214         /* if not, merge failed */
 215         if (*new_skb)
 216                 ret = NET_RX_SUCCESS;
 217
 218 out:
 219         if (orig_node)
 220                 batadv_orig_node_free_ref(orig_node);
 221         return ret;
 222 }
 223
 224 int batadv_frag_send_skb(struct sk_buff *skb, struct batadv_priv *bat_priv,
 225                          struct batadv_hard_iface *hard_iface,
 226                          const uint8_t dstaddr[])
 227 {
 228         struct batadv_unicast_packet tmp_uc, *unicast_packet;
 229         struct batadv_hard_iface *primary_if;
 230         struct sk_buff *frag_skb;
 231         struct batadv_unicast_frag_packet *frag1, *frag2;
 232         int uc_hdr_len = sizeof(*unicast_packet);
 233         int ucf_hdr_len = sizeof(*frag1);
 234         int data_len = skb->len - uc_hdr_len;
 235         int large_tail = 0, ret = NET_RX_DROP;
 236         uint16_t seqno;
 237
 238         primary_if = batadv_primary_if_get_selected(bat_priv);
 239         if (!primary_if)
 240                 goto dropped;
 241
 242         frag_skb = dev_alloc_skb(data_len - (data_len / 2) + ucf_hdr_len);
 243         if (!frag_skb)
 244                 goto dropped;
 245         skb_reserve(frag_skb, ucf_hdr_len);
 246
 247         unicast_packet = (struct batadv_unicast_packet *)skb->data;
 248         memcpy(&tmp_uc, unicast_packet, uc_hdr_len);
 249         skb_split(skb, frag_skb, data_len / 2 + uc_hdr_len);
 250
 251         if (batadv_skb_head_push(skb, ucf_hdr_len - uc_hdr_len) < 0 ||
 252             batadv_skb_head_push(frag_skb, ucf_hdr_len) < 0)
 253                 goto drop_frag;
 254
 255         frag1 = (struct batadv_unicast_frag_packet *)skb->data;
 256         frag2 = (struct batadv_unicast_frag_packet *)frag_skb->data;
 257
 258         memcpy(frag1, &tmp_uc, sizeof(tmp_uc));
 259
 260         frag1->header.ttl--;
 261         frag1->header.version = BATADV_COMPAT_VERSION;
 262         frag1->header.packet_type = BATADV_UNICAST_FRAG;
 263
 264         memcpy(frag1->orig, primary_if->net_dev->dev_addr, ETH_ALEN);
 265         memcpy(frag2, frag1, sizeof(*frag2));
 266
 267         if (data_len & 1)
 268                 large_tail = BATADV_UNI_FRAG_LARGETAIL;
 269
 270         frag1->flags = BATADV_UNI_FRAG_HEAD | large_tail;
 271         frag2->flags = large_tail;
 272
 273         seqno = atomic_add_return(2, &hard_iface->frag_seqno);
 274         frag1->seqno = htons(seqno - 1);
 275         frag2->seqno = htons(seqno);
 276
 277         batadv_send_skb_packet(skb, hard_iface, dstaddr);
 278         batadv_send_skb_packet(frag_skb, hard_iface, dstaddr);
 279         ret = NET_RX_SUCCESS;
 280         goto out;
 281
 282 drop_frag:
 283         kfree_skb(frag_skb);
 284 dropped:
 285         kfree_skb(skb);
 286 out:
 287         if (primary_if)
 288                 batadv_hardif_free_ref(primary_if);
 289         return ret;
 290 }
 291
 292 /**
 293  * batadv_unicast_push_and_fill_skb - extends the buffer and initializes the
 294  * common fields for unicast packets
 295  * @skb: packet
 296  * @hdr_size: amount of bytes to push at the beginning of the skb
 297  * @orig_node: the destination node
 298  *
 299  * Returns false if the buffer extension was not possible or true otherwise
 300  */
 301 static bool batadv_unicast_push_and_fill_skb(struct sk_buff *skb, int hdr_size,
 302                                              struct batadv_orig_node *orig_node)
 303 {
 304         struct batadv_unicast_packet *unicast_packet;
 305         uint8_t ttvn = (uint8_t)atomic_read(&orig_node->last_ttvn);
 306
 307         if (batadv_skb_head_push(skb, hdr_size) < 0)
 308                 return false;
 309
 310         unicast_packet = (struct batadv_unicast_packet *)skb->data;
 311         unicast_packet->header.version = BATADV_COMPAT_VERSION;
 312         /* batman packet type: unicast */
 313         unicast_packet->header.packet_type = BATADV_UNICAST;
 314         /* set unicast ttl */
 315         unicast_packet->header.ttl = BATADV_TTL;
 316         /* copy the destination for faster routing */
 317         memcpy(unicast_packet->dest, orig_node->orig, ETH_ALEN);
 318         /* set the destination tt version number */
 319         unicast_packet->ttvn = ttvn;
 320
 321         return true;
 322 }
 323
 324 /**
 325  * batadv_unicast_prepare_skb - encapsulate an skb with a unicast header
 326  * @skb: the skb containing the payload to encapsulate
 327  * @orig_node: the destination node
 328  *
 329  * Returns false if the payload could not be encapsulated or true otherwise
 330  */
 331 static bool batadv_unicast_prepare_skb(struct sk_buff *skb,
 332                                        struct batadv_orig_node *orig_node)
 333 {
 334         size_t uni_size = sizeof(struct batadv_unicast_packet);
 335         return batadv_unicast_push_and_fill_skb(skb, uni_size, orig_node);
 336 }
 337
 338 /**
 339  * batadv_unicast_4addr_prepare_skb - encapsulate an skb with a unicast4addr
 340  * header
 341  * @bat_priv: the bat priv with all the soft interface information
 342  * @skb: the skb containing the payload to encapsulate
 343  * @orig_node: the destination node
 344  * @packet_subtype: the batman 4addr packet subtype to use
 345  *
 346  * Returns false if the payload could not be encapsulated or true otherwise
 347  */
 348 bool batadv_unicast_4addr_prepare_skb(struct batadv_priv *bat_priv,
 349                                       struct sk_buff *skb,
 350                                       struct batadv_orig_node *orig,
 351                                       int packet_subtype)
 352 {
 353         struct batadv_hard_iface *primary_if;
 354         struct batadv_unicast_4addr_packet *unicast_4addr_packet;
 355         bool ret = false;
 356
 357         primary_if = batadv_primary_if_get_selected(bat_priv);
 358         if (!primary_if)
 359                 goto out;
 360
 361         /* pull the header space and fill the unicast_packet substructure.
 362          * We can do that because the first member of the unicast_4addr_packet
 363          * is of type struct unicast_packet
 364          */
 365         if (!batadv_unicast_push_and_fill_skb(skb,
 366                                               sizeof(*unicast_4addr_packet),
 367                                               orig))
 368                 goto out;
 369
 370         unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
 371         unicast_4addr_packet->u.header.packet_type = BATADV_UNICAST_4ADDR;
 372         memcpy(unicast_4addr_packet->src, primary_if->net_dev->dev_addr,
 373                ETH_ALEN);
 374         unicast_4addr_packet->subtype = packet_subtype;
 375         unicast_4addr_packet->reserved = 0;
 376
 377         ret = true;
 378 out:
 379         if (primary_if)
 380                 batadv_hardif_free_ref(primary_if);
 381         return ret;
 382 }
 383
 384 /**
 385  * batadv_unicast_generic_send_skb - send an skb as unicast
 386  * @bat_priv: the bat priv with all the soft interface information
 387  * @skb: payload to send
 388  * @packet_type: the batman unicast packet type to use
 389  * @packet_subtype: the batman packet subtype. It is ignored if packet_type is
 390  *                  not BATADV_UNICAT_4ADDR
 391  *
 392  * Returns 1 in case of error or 0 otherwise
 393  */
 394 int batadv_unicast_generic_send_skb(struct batadv_priv *bat_priv,
 395                                     struct sk_buff *skb, int packet_type,
 396                                     int packet_subtype)
 397 {
 398         struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
 399         struct batadv_unicast_packet *unicast_packet;
 400         struct batadv_orig_node *orig_node;
 401         struct batadv_neigh_node *neigh_node;
 402         int data_len = skb->len;
 403         int ret = NET_RX_DROP;
 404         unsigned int dev_mtu;
 405
 406         /* get routing information */
 407         if (is_multicast_ether_addr(ethhdr->h_dest)) {
 408                 orig_node = batadv_gw_get_selected_orig(bat_priv);
 409                 if (orig_node)
 410                         goto find_router;
 411         }
 412
 413         /* check for tt host - increases orig_node refcount.
 414          * returns NULL in case of AP isolation
 415          */
 416         orig_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
 417                                              ethhdr->h_dest);
 418
 419 find_router:
 420         /* find_router():
 421          *  - if orig_node is NULL it returns NULL
 422          *  - increases neigh_nodes refcount if found.
 423          */
 424         neigh_node = batadv_find_router(bat_priv, orig_node, NULL);
 425
 426         if (!neigh_node)
 427                 goto out;
 428
 429         switch (packet_type) {
 430         case BATADV_UNICAST:
 431                 batadv_unicast_prepare_skb(skb, orig_node);
 432                 break;
 433         case BATADV_UNICAST_4ADDR:
 434                 batadv_unicast_4addr_prepare_skb(bat_priv, skb, orig_node,
 435                                                  packet_subtype);
 436                 break;
 437         default:
 438                 /* this function supports UNICAST and UNICAST_4ADDR only. It
 439                  * should never be invoked with any other packet type
 440                  */
 441                 goto out;
 442         }
 443
 444         unicast_packet = (struct batadv_unicast_packet *)skb->data;
 445
 446         /* inform the destination node that we are still missing a correct route
 447          * for this client. The destination will receive this packet and will
 448          * try to reroute it because the ttvn contained in the header is less
 449          * than the current one
 450          */
 451         if (batadv_tt_global_client_is_roaming(bat_priv, ethhdr->h_dest))
 452                 unicast_packet->ttvn = unicast_packet->ttvn - 1;
 453
 454         dev_mtu = neigh_node->if_incoming->net_dev->mtu;
 455         /* fragmentation mechanism only works for UNICAST (now) */
 456         if (packet_type == BATADV_UNICAST &&
 457             atomic_read(&bat_priv->fragmentation) &&
 458             data_len + sizeof(*unicast_packet) > dev_mtu) {
 459                 /* send frag skb decreases ttl */
 460                 unicast_packet->header.ttl++;
 461                 ret = batadv_frag_send_skb(skb, bat_priv,
 462                                            neigh_node->if_incoming,
 463                                            neigh_node->addr);
 464                 goto out;
 465         }
 466
 467         if (batadv_send_skb_to_orig(skb, orig_node, NULL) != NET_XMIT_DROP)
 468                 ret = 0;
 469
 470 out:
 471         if (neigh_node)
 472                 batadv_neigh_node_free_ref(neigh_node);
 473         if (orig_node)
 474                 batadv_orig_node_free_ref(orig_node);
 475         if (ret == NET_RX_DROP)
 476                 kfree_skb(skb);
 477         return ret;
 478 }