net/batman-adv/unicast.c

   1 /* Copyright (C) 2010-2012 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
  43         up = (struct batadv_unicast_frag_packet *)skb->data;
  44         /* set skb to the first part and tmp_skb to the second part */
  45         if (up->flags & BATADV_UNI_FRAG_HEAD) {
  46                 tmp_skb = tfp->skb;
  47         } else {
  48                 tmp_skb = skb;
  49                 skb = tfp->skb;
  50         }
  51
  52         if (skb_linearize(skb) < 0 || skb_linearize(tmp_skb) < 0)
  53                 goto err;
  54
  55         skb_pull(tmp_skb, sizeof(*up));
  56         if (pskb_expand_head(skb, 0, tmp_skb->len, GFP_ATOMIC) < 0)
  57                 goto err;
  58
  59         /* move free entry to end */
  60         tfp->skb = NULL;
  61         tfp->seqno = 0;
  62         list_move_tail(&tfp->list, head);
  63
  64         memcpy(skb_put(skb, tmp_skb->len), tmp_skb->data, tmp_skb->len);
  65         kfree_skb(tmp_skb);
  66
  67         memmove(skb->data + uni_diff, skb->data, hdr_len);
  68         unicast_packet = (struct batadv_unicast_packet *)skb_pull(skb,
  69                                                                   uni_diff);
  70         unicast_packet->header.packet_type = BATADV_UNICAST;
  71
  72         return skb;
  73
  74 err:
  75         /* free buffered skb, skb will be freed later */
  76         kfree_skb(tfp->skb);
  77         return NULL;
  78 }
  79
  80 static void batadv_frag_create_entry(struct list_head *head,
  81                                      struct sk_buff *skb)
  82 {
  83         struct batadv_frag_packet_list_entry *tfp;
  84         struct batadv_unicast_frag_packet *up;
  85
  86         up = (struct batadv_unicast_frag_packet *)skb->data;
  87
  88         /* free and oldest packets stand at the end */
  89         tfp = list_entry((head)->prev, typeof(*tfp), list);
  90         kfree_skb(tfp->skb);
  91
  92         tfp->seqno = ntohs(up->seqno);
  93         tfp->skb = skb;
  94         list_move(&tfp->list, head);
  95         return;
  96 }
  97
  98 static int batadv_frag_create_buffer(struct list_head *head)
  99 {
 100         int i;
 101         struct batadv_frag_packet_list_entry *tfp;
 102
 103         for (i = 0; i < BATADV_FRAG_BUFFER_SIZE; i++) {
 104                 tfp = kmalloc(sizeof(*tfp), GFP_ATOMIC);
 105                 if (!tfp) {
 106                         batadv_frag_list_free(head);
 107                         return -ENOMEM;
 108                 }
 109                 tfp->skb = NULL;
 110                 tfp->seqno = 0;
 111                 INIT_LIST_HEAD(&tfp->list);
 112                 list_add(&tfp->list, head);
 113         }
 114
 115         return 0;
 116 }
 117
 118 static struct batadv_frag_packet_list_entry *
 119 batadv_frag_search_packet(struct list_head *head,
 120                           const struct batadv_unicast_frag_packet *up)
 121 {
 122         struct batadv_frag_packet_list_entry *tfp;
 123         struct batadv_unicast_frag_packet *tmp_up = NULL;
 124         uint16_t search_seqno;
 125
 126         if (up->flags & BATADV_UNI_FRAG_HEAD)
 127                 search_seqno = ntohs(up->seqno)+1;
 128         else
 129                 search_seqno = ntohs(up->seqno)-1;
 130
 131         list_for_each_entry(tfp, head, list) {
 132
 133                 if (!tfp->skb)
 134                         continue;
 135
 136                 if (tfp->seqno == ntohs(up->seqno))
 137                         goto mov_tail;
 138
 139                 tmp_up = (struct batadv_unicast_frag_packet *)tfp->skb->data;
 140
 141                 if (tfp->seqno == search_seqno) {
 142
 143                         if ((tmp_up->flags & BATADV_UNI_FRAG_HEAD) !=
 144                             (up->flags & BATADV_UNI_FRAG_HEAD))
 145                                 return tfp;
 146                         else
 147                                 goto mov_tail;
 148                 }
 149         }
 150         return NULL;
 151
 152 mov_tail:
 153         list_move_tail(&tfp->list, head);
 154         return NULL;
 155 }
 156
 157 void batadv_frag_list_free(struct list_head *head)
 158 {
 159         struct batadv_frag_packet_list_entry *pf, *tmp_pf;
 160
 161         if (!list_empty(head)) {
 162
 163                 list_for_each_entry_safe(pf, tmp_pf, head, list) {
 164                         kfree_skb(pf->skb);
 165                         list_del(&pf->list);
 166                         kfree(pf);
 167                 }
 168         }
 169         return;
 170 }
 171
 172 /* frag_reassemble_skb():
 173  * returns NET_RX_DROP if the operation failed - skb is left intact
 174  * returns NET_RX_SUCCESS if the fragment was buffered (skb_new will be NULL)
 175  * or the skb could be reassembled (skb_new will point to the new packet and
 176  * skb was freed)
 177  */
 178 int batadv_frag_reassemble_skb(struct sk_buff *skb,
 179                                struct batadv_priv *bat_priv,
 180                                struct sk_buff **new_skb)
 181 {
 182         struct batadv_orig_node *orig_node;
 183         struct batadv_frag_packet_list_entry *tmp_frag_entry;
 184         int ret = NET_RX_DROP;
 185         struct batadv_unicast_frag_packet *unicast_packet;
 186
 187         unicast_packet = (struct batadv_unicast_frag_packet *)skb->data;
 188         *new_skb = NULL;
 189
 190         orig_node = batadv_orig_hash_find(bat_priv, unicast_packet->orig);
 191         if (!orig_node)
 192                 goto out;
 193
 194         orig_node->last_frag_packet = jiffies;
 195
 196         if (list_empty(&orig_node->frag_list) &&
 197             batadv_frag_create_buffer(&orig_node->frag_list)) {
 198                 pr_debug("couldn't create frag buffer\n");
 199                 goto out;
 200         }
 201
 202         tmp_frag_entry = batadv_frag_search_packet(&orig_node->frag_list,
 203                                                    unicast_packet);
 204
 205         if (!tmp_frag_entry) {
 206                 batadv_frag_create_entry(&orig_node->frag_list, skb);
 207                 ret = NET_RX_SUCCESS;
 208                 goto out;
 209         }
 210
 211         *new_skb = batadv_frag_merge_packet(&orig_node->frag_list,
 212                                             tmp_frag_entry, skb);
 213         /* if not, merge failed */
 214         if (*new_skb)
 215                 ret = NET_RX_SUCCESS;
 216
 217 out:
 218         if (orig_node)
 219                 batadv_orig_node_free_ref(orig_node);
 220         return ret;
 221 }
 222
 223 int batadv_frag_send_skb(struct sk_buff *skb, struct batadv_priv *bat_priv,
 224                          struct batadv_hard_iface *hard_iface,
 225                          const uint8_t dstaddr[])
 226 {
 227         struct batadv_unicast_packet tmp_uc, *unicast_packet;
 228         struct batadv_hard_iface *primary_if;
 229         struct sk_buff *frag_skb;
 230         struct batadv_unicast_frag_packet *frag1, *frag2;
 231         int uc_hdr_len = sizeof(*unicast_packet);
 232         int ucf_hdr_len = sizeof(*frag1);
 233         int data_len = skb->len - uc_hdr_len;
 234         int large_tail = 0, ret = NET_RX_DROP;
 235         uint16_t seqno;
 236
 237         primary_if = batadv_primary_if_get_selected(bat_priv);
 238         if (!primary_if)
 239                 goto dropped;
 240
 241         frag_skb = dev_alloc_skb(data_len - (data_len / 2) + ucf_hdr_len);
 242         if (!frag_skb)
 243                 goto dropped;
 244         skb_reserve(frag_skb, ucf_hdr_len);
 245
 246         unicast_packet = (struct batadv_unicast_packet *)skb->data;
 247         memcpy(&tmp_uc, unicast_packet, uc_hdr_len);
 248         skb_split(skb, frag_skb, data_len / 2 + uc_hdr_len);
 249
 250         if (batadv_skb_head_push(skb, ucf_hdr_len - uc_hdr_len) < 0 ||
 251             batadv_skb_head_push(frag_skb, ucf_hdr_len) < 0)
 252                 goto drop_frag;
 253
 254         frag1 = (struct batadv_unicast_frag_packet *)skb->data;
 255         frag2 = (struct batadv_unicast_frag_packet *)frag_skb->data;
 256
 257         memcpy(frag1, &tmp_uc, sizeof(tmp_uc));
 258
 259         frag1->header.ttl--;
 260         frag1->header.version = BATADV_COMPAT_VERSION;
 261         frag1->header.packet_type = BATADV_UNICAST_FRAG;
 262
 263         memcpy(frag1->orig, primary_if->net_dev->dev_addr, ETH_ALEN);
 264         memcpy(frag2, frag1, sizeof(*frag2));
 265
 266         if (data_len & 1)
 267                 large_tail = BATADV_UNI_FRAG_LARGETAIL;
 268
 269         frag1->flags = BATADV_UNI_FRAG_HEAD | large_tail;
 270         frag2->flags = large_tail;
 271
 272         seqno = atomic_add_return(2, &hard_iface->frag_seqno);
 273         frag1->seqno = htons(seqno - 1);
 274         frag2->seqno = htons(seqno);
 275
 276         batadv_send_skb_packet(skb, hard_iface, dstaddr);
 277         batadv_send_skb_packet(frag_skb, hard_iface, dstaddr);
 278         ret = NET_RX_SUCCESS;
 279         goto out;
 280
 281 drop_frag:
 282         kfree_skb(frag_skb);
 283 dropped:
 284         kfree_skb(skb);
 285 out:
 286         if (primary_if)
 287                 batadv_hardif_free_ref(primary_if);
 288         return ret;
 289 }
 290
 291 int batadv_unicast_send_skb(struct sk_buff *skb, struct batadv_priv *bat_priv)
 292 {
 293         struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
 294         struct batadv_unicast_packet *unicast_packet;
 295         struct batadv_orig_node *orig_node;
 296         struct batadv_neigh_node *neigh_node;
 297         int data_len = skb->len;
 298         int ret = 1;
 299         unsigned int dev_mtu;
 300
 301         /* get routing information */
 302         if (is_multicast_ether_addr(ethhdr->h_dest)) {
 303                 orig_node = batadv_gw_get_selected_orig(bat_priv);
 304                 if (orig_node)
 305                         goto find_router;
 306         }
 307
 308         /* check for tt host - increases orig_node refcount.
 309          * returns NULL in case of AP isolation
 310          */
 311         orig_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
 312                                              ethhdr->h_dest);
 313
 314 find_router:
 315         /* find_router():
 316          *  - if orig_node is NULL it returns NULL
 317          *  - increases neigh_nodes refcount if found.
 318          */
 319         neigh_node = batadv_find_router(bat_priv, orig_node, NULL);
 320
 321         if (!neigh_node)
 322                 goto out;
 323
 324         if (batadv_skb_head_push(skb, sizeof(*unicast_packet)) < 0)
 325                 goto out;
 326
 327         unicast_packet = (struct batadv_unicast_packet *)skb->data;
 328
 329         unicast_packet->header.version = BATADV_COMPAT_VERSION;
 330         /* batman packet type: unicast */
 331         unicast_packet->header.packet_type = BATADV_UNICAST;
 332         /* set unicast ttl */
 333         unicast_packet->header.ttl = BATADV_TTL;
 334         /* copy the destination for faster routing */
 335         memcpy(unicast_packet->dest, orig_node->orig, ETH_ALEN);
 336         /* set the destination tt version number */
 337         unicast_packet->ttvn =
 338                 (uint8_t)atomic_read(&orig_node->last_ttvn);
 339
 340         /* inform the destination node that we are still missing a correct route
 341          * for this client. The destination will receive this packet and will
 342          * try to reroute it because the ttvn contained in the header is less
 343          * than the current one
 344          */
 345         if (batadv_tt_global_client_is_roaming(bat_priv, ethhdr->h_dest))
 346                 unicast_packet->ttvn = unicast_packet->ttvn - 1;
 347
 348         dev_mtu = neigh_node->if_incoming->net_dev->mtu;
 349         if (atomic_read(&bat_priv->fragmentation) &&
 350             data_len + sizeof(*unicast_packet) > dev_mtu) {
 351                 /* send frag skb decreases ttl */
 352                 unicast_packet->header.ttl++;
 353                 ret = batadv_frag_send_skb(skb, bat_priv,
 354                                            neigh_node->if_incoming,
 355                                            neigh_node->addr);
 356                 goto out;
 357         }
 358
 359         batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
 360         ret = 0;
 361         goto out;
 362
 363 out:
 364         if (neigh_node)
 365                 batadv_neigh_node_free_ref(neigh_node);
 366         if (orig_node)
 367                 batadv_orig_node_free_ref(orig_node);
 368         if (ret == 1)
 369                 kfree_skb(skb);
 370         return ret;
 371 }