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         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         int 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
 137                 if (!tfp->skb)
 138                         continue;
 139
 140                 if (tfp->seqno == ntohs(up->seqno))
 141                         goto mov_tail;
 142
 143                 tmp_up = (struct batadv_unicast_frag_packet *)tfp->skb->data;
 144
 145                 if (tfp->seqno == search_seqno) {
 146                         is_head_tmp = !!(tmp_up->flags & BATADV_UNI_FRAG_HEAD);
 147                         if (is_head_tmp != is_head)
 148                                 return tfp;
 149                         else
 150                                 goto mov_tail;
 151                 }
 152         }
 153         return NULL;
 154
 155 mov_tail:
 156         list_move_tail(&tfp->list, head);
 157         return NULL;
 158 }
 159
 160 void batadv_frag_list_free(struct list_head *head)
 161 {
 162         struct batadv_frag_packet_list_entry *pf, *tmp_pf;
 163
 164         if (!list_empty(head)) {
 165
 166                 list_for_each_entry_safe(pf, tmp_pf, head, list) {
 167                         kfree_skb(pf->skb);
 168                         list_del(&pf->list);
 169                         kfree(pf);
 170                 }
 171         }
 172         return;
 173 }
 174
 175 /* frag_reassemble_skb():
 176  * returns NET_RX_DROP if the operation failed - skb is left intact
 177  * returns NET_RX_SUCCESS if the fragment was buffered (skb_new will be NULL)
 178  * or the skb could be reassembled (skb_new will point to the new packet and
 179  * skb was freed)
 180  */
 181 int batadv_frag_reassemble_skb(struct sk_buff *skb,
 182                                struct batadv_priv *bat_priv,
 183                                struct sk_buff **new_skb)
 184 {
 185         struct batadv_orig_node *orig_node;
 186         struct batadv_frag_packet_list_entry *tmp_frag_entry;
 187         int ret = NET_RX_DROP;
 188         struct batadv_unicast_frag_packet *unicast_packet;
 189
 190         unicast_packet = (struct batadv_unicast_frag_packet *)skb->data;
 191         *new_skb = NULL;
 192
 193         orig_node = batadv_orig_hash_find(bat_priv, unicast_packet->orig);
 194         if (!orig_node)
 195                 goto out;
 196
 197         orig_node->last_frag_packet = jiffies;
 198
 199         if (list_empty(&orig_node->frag_list) &&
 200             batadv_frag_create_buffer(&orig_node->frag_list)) {
 201                 pr_debug("couldn't create frag buffer\n");
 202                 goto out;
 203         }
 204
 205         tmp_frag_entry = batadv_frag_search_packet(&orig_node->frag_list,
 206                                                    unicast_packet);
 207
 208         if (!tmp_frag_entry) {
 209                 batadv_frag_create_entry(&orig_node->frag_list, skb);
 210                 ret = NET_RX_SUCCESS;
 211                 goto out;
 212         }
 213
 214         *new_skb = batadv_frag_merge_packet(&orig_node->frag_list,
 215                                             tmp_frag_entry, skb);
 216         /* if not, merge failed */
 217         if (*new_skb)
 218                 ret = NET_RX_SUCCESS;
 219
 220 out:
 221         if (orig_node)
 222                 batadv_orig_node_free_ref(orig_node);
 223         return ret;
 224 }
 225
 226 int batadv_frag_send_skb(struct sk_buff *skb, struct batadv_priv *bat_priv,
 227                          struct batadv_hard_iface *hard_iface,
 228                          const uint8_t dstaddr[])
 229 {
 230         struct batadv_unicast_packet tmp_uc, *unicast_packet;
 231         struct batadv_hard_iface *primary_if;
 232         struct sk_buff *frag_skb;
 233         struct batadv_unicast_frag_packet *frag1, *frag2;
 234         int uc_hdr_len = sizeof(*unicast_packet);
 235         int ucf_hdr_len = sizeof(*frag1);
 236         int data_len = skb->len - uc_hdr_len;
 237         int large_tail = 0, ret = NET_RX_DROP;
 238         uint16_t seqno;
 239
 240         primary_if = batadv_primary_if_get_selected(bat_priv);
 241         if (!primary_if)
 242                 goto dropped;
 243
 244         frag_skb = dev_alloc_skb(data_len - (data_len / 2) + ucf_hdr_len);
 245         if (!frag_skb)
 246                 goto dropped;
 247         skb_reserve(frag_skb, ucf_hdr_len);
 248
 249         unicast_packet = (struct batadv_unicast_packet *)skb->data;
 250         memcpy(&tmp_uc, unicast_packet, uc_hdr_len);
 251         skb_split(skb, frag_skb, data_len / 2 + uc_hdr_len);
 252
 253         if (batadv_skb_head_push(skb, ucf_hdr_len - uc_hdr_len) < 0 ||
 254             batadv_skb_head_push(frag_skb, ucf_hdr_len) < 0)
 255                 goto drop_frag;
 256
 257         frag1 = (struct batadv_unicast_frag_packet *)skb->data;
 258         frag2 = (struct batadv_unicast_frag_packet *)frag_skb->data;
 259
 260         memcpy(frag1, &tmp_uc, sizeof(tmp_uc));
 261
 262         frag1->header.ttl--;
 263         frag1->header.version = BATADV_COMPAT_VERSION;
 264         frag1->header.packet_type = BATADV_UNICAST_FRAG;
 265
 266         memcpy(frag1->orig, primary_if->net_dev->dev_addr, ETH_ALEN);
 267         memcpy(frag2, frag1, sizeof(*frag2));
 268
 269         if (data_len & 1)
 270                 large_tail = BATADV_UNI_FRAG_LARGETAIL;
 271
 272         frag1->flags = BATADV_UNI_FRAG_HEAD | large_tail;
 273         frag2->flags = large_tail;
 274
 275         seqno = atomic_add_return(2, &hard_iface->frag_seqno);
 276         frag1->seqno = htons(seqno - 1);
 277         frag2->seqno = htons(seqno);
 278
 279         batadv_send_skb_packet(skb, hard_iface, dstaddr);
 280         batadv_send_skb_packet(frag_skb, hard_iface, dstaddr);
 281         ret = NET_RX_SUCCESS;
 282         goto out;
 283
 284 drop_frag:
 285         kfree_skb(frag_skb);
 286 dropped:
 287         kfree_skb(skb);
 288 out:
 289         if (primary_if)
 290                 batadv_hardif_free_ref(primary_if);
 291         return ret;
 292 }
 293
 294 int batadv_unicast_send_skb(struct sk_buff *skb, struct batadv_priv *bat_priv)
 295 {
 296         struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
 297         struct batadv_unicast_packet *unicast_packet;
 298         struct batadv_orig_node *orig_node;
 299         struct batadv_neigh_node *neigh_node;
 300         int data_len = skb->len;
 301         int ret = 1;
 302         unsigned int dev_mtu;
 303
 304         /* get routing information */
 305         if (is_multicast_ether_addr(ethhdr->h_dest)) {
 306                 orig_node = batadv_gw_get_selected_orig(bat_priv);
 307                 if (orig_node)
 308                         goto find_router;
 309         }
 310
 311         /* check for tt host - increases orig_node refcount.
 312          * returns NULL in case of AP isolation
 313          */
 314         orig_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
 315                                              ethhdr->h_dest);
 316
 317 find_router:
 318         /* find_router():
 319          *  - if orig_node is NULL it returns NULL
 320          *  - increases neigh_nodes refcount if found.
 321          */
 322         neigh_node = batadv_find_router(bat_priv, orig_node, NULL);
 323
 324         if (!neigh_node)
 325                 goto out;
 326
 327         if (batadv_skb_head_push(skb, sizeof(*unicast_packet)) < 0)
 328                 goto out;
 329
 330         unicast_packet = (struct batadv_unicast_packet *)skb->data;
 331
 332         unicast_packet->header.version = BATADV_COMPAT_VERSION;
 333         /* batman packet type: unicast */
 334         unicast_packet->header.packet_type = BATADV_UNICAST;
 335         /* set unicast ttl */
 336         unicast_packet->header.ttl = BATADV_TTL;
 337         /* copy the destination for faster routing */
 338         memcpy(unicast_packet->dest, orig_node->orig, ETH_ALEN);
 339         /* set the destination tt version number */
 340         unicast_packet->ttvn = (uint8_t)atomic_read(&orig_node->last_ttvn);
 341
 342         /* inform the destination node that we are still missing a correct route
 343          * for this client. The destination will receive this packet and will
 344          * try to reroute it because the ttvn contained in the header is less
 345          * than the current one
 346          */
 347         if (batadv_tt_global_client_is_roaming(bat_priv, ethhdr->h_dest))
 348                 unicast_packet->ttvn = unicast_packet->ttvn - 1;
 349
 350         dev_mtu = neigh_node->if_incoming->net_dev->mtu;
 351         if (atomic_read(&bat_priv->fragmentation) &&
 352             data_len + sizeof(*unicast_packet) > dev_mtu) {
 353                 /* send frag skb decreases ttl */
 354                 unicast_packet->header.ttl++;
 355                 ret = batadv_frag_send_skb(skb, bat_priv,
 356                                            neigh_node->if_incoming,
 357                                            neigh_node->addr);
 358                 goto out;
 359         }
 360
 361         batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
 362         ret = 0;
 363         goto out;
 364
 365 out:
 366         if (neigh_node)
 367                 batadv_neigh_node_free_ref(neigh_node);
 368         if (orig_node)
 369                 batadv_orig_node_free_ref(orig_node);
 370         if (ret == 1)
 371                 kfree_skb(skb);
 372         return ret;
 373 }