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 frag_packet_list_entry *tfp,
  35                          struct sk_buff *skb)
  36 {
  37         struct unicast_frag_packet *up =
  38                 (struct unicast_frag_packet *)skb->data;
  39         struct sk_buff *tmp_skb;
  40         struct unicast_packet *unicast_packet;
  41         int hdr_len = sizeof(*unicast_packet);
  42         int uni_diff = sizeof(*up) - hdr_len;
  43
  44         /* set skb to the first part and tmp_skb to the second part */
  45         if (up->flags & 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 unicast_packet *)skb_pull(skb, uni_diff);
  69         unicast_packet->header.packet_type = BAT_UNICAST;
  70
  71         return skb;
  72
  73 err:
  74         /* free buffered skb, skb will be freed later */
  75         kfree_skb(tfp->skb);
  76         return NULL;
  77 }
  78
  79 static void batadv_frag_create_entry(struct list_head *head,
  80                                      struct sk_buff *skb)
  81 {
  82         struct frag_packet_list_entry *tfp;
  83         struct unicast_frag_packet *up =
  84                 (struct unicast_frag_packet *)skb->data;
  85
  86         /* free and oldest packets stand at the end */
  87         tfp = list_entry((head)->prev, typeof(*tfp), list);
  88         kfree_skb(tfp->skb);
  89
  90         tfp->seqno = ntohs(up->seqno);
  91         tfp->skb = skb;
  92         list_move(&tfp->list, head);
  93         return;
  94 }
  95
  96 static int batadv_frag_create_buffer(struct list_head *head)
  97 {
  98         int i;
  99         struct frag_packet_list_entry *tfp;
 100
 101         for (i = 0; i < BATADV_FRAG_BUFFER_SIZE; i++) {
 102                 tfp = kmalloc(sizeof(*tfp), GFP_ATOMIC);
 103                 if (!tfp) {
 104                         batadv_frag_list_free(head);
 105                         return -ENOMEM;
 106                 }
 107                 tfp->skb = NULL;
 108                 tfp->seqno = 0;
 109                 INIT_LIST_HEAD(&tfp->list);
 110                 list_add(&tfp->list, head);
 111         }
 112
 113         return 0;
 114 }
 115
 116 static struct frag_packet_list_entry *
 117 batadv_frag_search_packet(struct list_head *head,
 118                           const struct unicast_frag_packet *up)
 119 {
 120         struct frag_packet_list_entry *tfp;
 121         struct unicast_frag_packet *tmp_up = NULL;
 122         uint16_t search_seqno;
 123
 124         if (up->flags & UNI_FRAG_HEAD)
 125                 search_seqno = ntohs(up->seqno)+1;
 126         else
 127                 search_seqno = ntohs(up->seqno)-1;
 128
 129         list_for_each_entry(tfp, head, list) {
 130
 131                 if (!tfp->skb)
 132                         continue;
 133
 134                 if (tfp->seqno == ntohs(up->seqno))
 135                         goto mov_tail;
 136
 137                 tmp_up = (struct unicast_frag_packet *)tfp->skb->data;
 138
 139                 if (tfp->seqno == search_seqno) {
 140
 141                         if ((tmp_up->flags & UNI_FRAG_HEAD) !=
 142                             (up->flags & UNI_FRAG_HEAD))
 143                                 return tfp;
 144                         else
 145                                 goto mov_tail;
 146                 }
 147         }
 148         return NULL;
 149
 150 mov_tail:
 151         list_move_tail(&tfp->list, head);
 152         return NULL;
 153 }
 154
 155 void batadv_frag_list_free(struct list_head *head)
 156 {
 157         struct frag_packet_list_entry *pf, *tmp_pf;
 158
 159         if (!list_empty(head)) {
 160
 161                 list_for_each_entry_safe(pf, tmp_pf, head, list) {
 162                         kfree_skb(pf->skb);
 163                         list_del(&pf->list);
 164                         kfree(pf);
 165                 }
 166         }
 167         return;
 168 }
 169
 170 /* frag_reassemble_skb():
 171  * returns NET_RX_DROP if the operation failed - skb is left intact
 172  * returns NET_RX_SUCCESS if the fragment was buffered (skb_new will be NULL)
 173  * or the skb could be reassembled (skb_new will point to the new packet and
 174  * skb was freed)
 175  */
 176 int batadv_frag_reassemble_skb(struct sk_buff *skb, struct bat_priv *bat_priv,
 177                                struct sk_buff **new_skb)
 178 {
 179         struct orig_node *orig_node;
 180         struct frag_packet_list_entry *tmp_frag_entry;
 181         int ret = NET_RX_DROP;
 182         struct unicast_frag_packet *unicast_packet =
 183                 (struct unicast_frag_packet *)skb->data;
 184
 185         *new_skb = NULL;
 186
 187         orig_node = batadv_orig_hash_find(bat_priv, unicast_packet->orig);
 188         if (!orig_node)
 189                 goto out;
 190
 191         orig_node->last_frag_packet = jiffies;
 192
 193         if (list_empty(&orig_node->frag_list) &&
 194             batadv_frag_create_buffer(&orig_node->frag_list)) {
 195                 pr_debug("couldn't create frag buffer\n");
 196                 goto out;
 197         }
 198
 199         tmp_frag_entry = batadv_frag_search_packet(&orig_node->frag_list,
 200                                                    unicast_packet);
 201
 202         if (!tmp_frag_entry) {
 203                 batadv_frag_create_entry(&orig_node->frag_list, skb);
 204                 ret = NET_RX_SUCCESS;
 205                 goto out;
 206         }
 207
 208         *new_skb = batadv_frag_merge_packet(&orig_node->frag_list,
 209                                             tmp_frag_entry, skb);
 210         /* if not, merge failed */
 211         if (*new_skb)
 212                 ret = NET_RX_SUCCESS;
 213
 214 out:
 215         if (orig_node)
 216                 batadv_orig_node_free_ref(orig_node);
 217         return ret;
 218 }
 219
 220 int batadv_frag_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv,
 221                          struct hard_iface *hard_iface, const uint8_t dstaddr[])
 222 {
 223         struct unicast_packet tmp_uc, *unicast_packet;
 224         struct hard_iface *primary_if;
 225         struct sk_buff *frag_skb;
 226         struct unicast_frag_packet *frag1, *frag2;
 227         int uc_hdr_len = sizeof(*unicast_packet);
 228         int ucf_hdr_len = sizeof(*frag1);
 229         int data_len = skb->len - uc_hdr_len;
 230         int large_tail = 0, ret = NET_RX_DROP;
 231         uint16_t seqno;
 232
 233         primary_if = batadv_primary_if_get_selected(bat_priv);
 234         if (!primary_if)
 235                 goto dropped;
 236
 237         frag_skb = dev_alloc_skb(data_len - (data_len / 2) + ucf_hdr_len);
 238         if (!frag_skb)
 239                 goto dropped;
 240         skb_reserve(frag_skb, ucf_hdr_len);
 241
 242         unicast_packet = (struct unicast_packet *)skb->data;
 243         memcpy(&tmp_uc, unicast_packet, uc_hdr_len);
 244         skb_split(skb, frag_skb, data_len / 2 + uc_hdr_len);
 245
 246         if (batadv_skb_head_push(skb, ucf_hdr_len - uc_hdr_len) < 0 ||
 247             batadv_skb_head_push(frag_skb, ucf_hdr_len) < 0)
 248                 goto drop_frag;
 249
 250         frag1 = (struct unicast_frag_packet *)skb->data;
 251         frag2 = (struct unicast_frag_packet *)frag_skb->data;
 252
 253         memcpy(frag1, &tmp_uc, sizeof(tmp_uc));
 254
 255         frag1->header.ttl--;
 256         frag1->header.version = BATADV_COMPAT_VERSION;
 257         frag1->header.packet_type = BAT_UNICAST_FRAG;
 258
 259         memcpy(frag1->orig, primary_if->net_dev->dev_addr, ETH_ALEN);
 260         memcpy(frag2, frag1, sizeof(*frag2));
 261
 262         if (data_len & 1)
 263                 large_tail = UNI_FRAG_LARGETAIL;
 264
 265         frag1->flags = UNI_FRAG_HEAD | large_tail;
 266         frag2->flags = large_tail;
 267
 268         seqno = atomic_add_return(2, &hard_iface->frag_seqno);
 269         frag1->seqno = htons(seqno - 1);
 270         frag2->seqno = htons(seqno);
 271
 272         batadv_send_skb_packet(skb, hard_iface, dstaddr);
 273         batadv_send_skb_packet(frag_skb, hard_iface, dstaddr);
 274         ret = NET_RX_SUCCESS;
 275         goto out;
 276
 277 drop_frag:
 278         kfree_skb(frag_skb);
 279 dropped:
 280         kfree_skb(skb);
 281 out:
 282         if (primary_if)
 283                 batadv_hardif_free_ref(primary_if);
 284         return ret;
 285 }
 286
 287 int batadv_unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv)
 288 {
 289         struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
 290         struct unicast_packet *unicast_packet;
 291         struct orig_node *orig_node;
 292         struct neigh_node *neigh_node;
 293         int data_len = skb->len;
 294         int ret = 1;
 295
 296         /* get routing information */
 297         if (is_multicast_ether_addr(ethhdr->h_dest)) {
 298                 orig_node = batadv_gw_get_selected_orig(bat_priv);
 299                 if (orig_node)
 300                         goto find_router;
 301         }
 302
 303         /* check for tt host - increases orig_node refcount.
 304          * returns NULL in case of AP isolation
 305          */
 306         orig_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
 307                                              ethhdr->h_dest);
 308 find_router:
 309         /* find_router():
 310          *  - if orig_node is NULL it returns NULL
 311          *  - increases neigh_nodes refcount if found.
 312          */
 313         neigh_node = batadv_find_router(bat_priv, orig_node, NULL);
 314         if (!neigh_node)
 315                 goto out;
 316
 317         if (batadv_skb_head_push(skb, sizeof(*unicast_packet)) < 0)
 318                 goto out;
 319
 320         unicast_packet = (struct unicast_packet *)skb->data;
 321
 322         unicast_packet->header.version = BATADV_COMPAT_VERSION;
 323         /* batman packet type: unicast */
 324         unicast_packet->header.packet_type = BAT_UNICAST;
 325         /* set unicast ttl */
 326         unicast_packet->header.ttl = TTL;
 327         /* copy the destination for faster routing */
 328         memcpy(unicast_packet->dest, orig_node->orig, ETH_ALEN);
 329         /* set the destination tt version number */
 330         unicast_packet->ttvn =
 331                 (uint8_t)atomic_read(&orig_node->last_ttvn);
 332
 333         /* inform the destination node that we are still missing a correct route
 334          * for this client. The destination will receive this packet and will
 335          * try to reroute it because the ttvn contained in the header is less
 336          * than the current one
 337          */
 338         if (batadv_tt_global_client_is_roaming(bat_priv, ethhdr->h_dest))
 339                 unicast_packet->ttvn = unicast_packet->ttvn - 1;
 340
 341         if (atomic_read(&bat_priv->fragmentation) &&
 342             data_len + sizeof(*unicast_packet) >
 343                                 neigh_node->if_incoming->net_dev->mtu) {
 344                 /* send frag skb decreases ttl */
 345                 unicast_packet->header.ttl++;
 346                 ret = batadv_frag_send_skb(skb, bat_priv,
 347                                            neigh_node->if_incoming,
 348                                            neigh_node->addr);
 349                 goto out;
 350         }
 351
 352         batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
 353         ret = 0;
 354         goto out;
 355
 356 out:
 357         if (neigh_node)
 358                 batadv_neigh_node_free_ref(neigh_node);
 359         if (orig_node)
 360                 batadv_orig_node_free_ref(orig_node);
 361         if (ret == 1)
 362                 kfree_skb(skb);
 363         return ret;
 364 }