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 *frag_merge_packet(struct list_head *head,
  33                                          struct frag_packet_list_entry *tfp,
  34                                          struct sk_buff *skb)
  35 {
  36         struct unicast_frag_packet *up =
  37                 (struct unicast_frag_packet *)skb->data;
  38         struct sk_buff *tmp_skb;
  39         struct unicast_packet *unicast_packet;
  40         int hdr_len = sizeof(*unicast_packet);
  41         int uni_diff = sizeof(*up) - hdr_len;
  42
  43         /* set skb to the first part and tmp_skb to the second part */
  44         if (up->flags & UNI_FRAG_HEAD) {
  45                 tmp_skb = tfp->skb;
  46         } else {
  47                 tmp_skb = skb;
  48                 skb = tfp->skb;
  49         }
  50
  51         if (skb_linearize(skb) < 0 || skb_linearize(tmp_skb) < 0)
  52                 goto err;
  53
  54         skb_pull(tmp_skb, sizeof(*up));
  55         if (pskb_expand_head(skb, 0, tmp_skb->len, GFP_ATOMIC) < 0)
  56                 goto err;
  57
  58         /* move free entry to end */
  59         tfp->skb = NULL;
  60         tfp->seqno = 0;
  61         list_move_tail(&tfp->list, head);
  62
  63         memcpy(skb_put(skb, tmp_skb->len), tmp_skb->data, tmp_skb->len);
  64         kfree_skb(tmp_skb);
  65
  66         memmove(skb->data + uni_diff, skb->data, hdr_len);
  67         unicast_packet = (struct unicast_packet *)skb_pull(skb, uni_diff);
  68         unicast_packet->header.packet_type = BAT_UNICAST;
  69
  70         return skb;
  71
  72 err:
  73         /* free buffered skb, skb will be freed later */
  74         kfree_skb(tfp->skb);
  75         return NULL;
  76 }
  77
  78 static void frag_create_entry(struct list_head *head, struct sk_buff *skb)
  79 {
  80         struct frag_packet_list_entry *tfp;
  81         struct unicast_frag_packet *up =
  82                 (struct unicast_frag_packet *)skb->data;
  83
  84         /* free and oldest packets stand at the end */
  85         tfp = list_entry((head)->prev, typeof(*tfp), list);
  86         kfree_skb(tfp->skb);
  87
  88         tfp->seqno = ntohs(up->seqno);
  89         tfp->skb = skb;
  90         list_move(&tfp->list, head);
  91         return;
  92 }
  93
  94 static int frag_create_buffer(struct list_head *head)
  95 {
  96         int i;
  97         struct frag_packet_list_entry *tfp;
  98
  99         for (i = 0; i < FRAG_BUFFER_SIZE; i++) {
 100                 tfp = kmalloc(sizeof(*tfp), GFP_ATOMIC);
 101                 if (!tfp) {
 102                         batadv_frag_list_free(head);
 103                         return -ENOMEM;
 104                 }
 105                 tfp->skb = NULL;
 106                 tfp->seqno = 0;
 107                 INIT_LIST_HEAD(&tfp->list);
 108                 list_add(&tfp->list, head);
 109         }
 110
 111         return 0;
 112 }
 113
 114 static struct frag_packet_list_entry *frag_search_packet(struct list_head *head,
 115                                            const struct unicast_frag_packet *up)
 116 {
 117         struct frag_packet_list_entry *tfp;
 118         struct unicast_frag_packet *tmp_up = NULL;
 119         uint16_t search_seqno;
 120
 121         if (up->flags & UNI_FRAG_HEAD)
 122                 search_seqno = ntohs(up->seqno)+1;
 123         else
 124                 search_seqno = ntohs(up->seqno)-1;
 125
 126         list_for_each_entry(tfp, head, list) {
 127
 128                 if (!tfp->skb)
 129                         continue;
 130
 131                 if (tfp->seqno == ntohs(up->seqno))
 132                         goto mov_tail;
 133
 134                 tmp_up = (struct unicast_frag_packet *)tfp->skb->data;
 135
 136                 if (tfp->seqno == search_seqno) {
 137
 138                         if ((tmp_up->flags & UNI_FRAG_HEAD) !=
 139                             (up->flags & UNI_FRAG_HEAD))
 140                                 return tfp;
 141                         else
 142                                 goto mov_tail;
 143                 }
 144         }
 145         return NULL;
 146
 147 mov_tail:
 148         list_move_tail(&tfp->list, head);
 149         return NULL;
 150 }
 151
 152 void batadv_frag_list_free(struct list_head *head)
 153 {
 154         struct frag_packet_list_entry *pf, *tmp_pf;
 155
 156         if (!list_empty(head)) {
 157
 158                 list_for_each_entry_safe(pf, tmp_pf, head, list) {
 159                         kfree_skb(pf->skb);
 160                         list_del(&pf->list);
 161                         kfree(pf);
 162                 }
 163         }
 164         return;
 165 }
 166
 167 /* frag_reassemble_skb():
 168  * returns NET_RX_DROP if the operation failed - skb is left intact
 169  * returns NET_RX_SUCCESS if the fragment was buffered (skb_new will be NULL)
 170  * or the skb could be reassembled (skb_new will point to the new packet and
 171  * skb was freed)
 172  */
 173 int batadv_frag_reassemble_skb(struct sk_buff *skb, struct bat_priv *bat_priv,
 174                                struct sk_buff **new_skb)
 175 {
 176         struct orig_node *orig_node;
 177         struct frag_packet_list_entry *tmp_frag_entry;
 178         int ret = NET_RX_DROP;
 179         struct unicast_frag_packet *unicast_packet =
 180                 (struct unicast_frag_packet *)skb->data;
 181
 182         *new_skb = NULL;
 183
 184         orig_node = batadv_orig_hash_find(bat_priv, unicast_packet->orig);
 185         if (!orig_node)
 186                 goto out;
 187
 188         orig_node->last_frag_packet = jiffies;
 189
 190         if (list_empty(&orig_node->frag_list) &&
 191             frag_create_buffer(&orig_node->frag_list)) {
 192                 pr_debug("couldn't create frag buffer\n");
 193                 goto out;
 194         }
 195
 196         tmp_frag_entry = frag_search_packet(&orig_node->frag_list,
 197                                             unicast_packet);
 198
 199         if (!tmp_frag_entry) {
 200                 frag_create_entry(&orig_node->frag_list, skb);
 201                 ret = NET_RX_SUCCESS;
 202                 goto out;
 203         }
 204
 205         *new_skb = frag_merge_packet(&orig_node->frag_list, tmp_frag_entry,
 206                                      skb);
 207         /* if not, merge failed */
 208         if (*new_skb)
 209                 ret = NET_RX_SUCCESS;
 210
 211 out:
 212         if (orig_node)
 213                 batadv_orig_node_free_ref(orig_node);
 214         return ret;
 215 }
 216
 217 int batadv_frag_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv,
 218                          struct hard_iface *hard_iface, const uint8_t dstaddr[])
 219 {
 220         struct unicast_packet tmp_uc, *unicast_packet;
 221         struct hard_iface *primary_if;
 222         struct sk_buff *frag_skb;
 223         struct unicast_frag_packet *frag1, *frag2;
 224         int uc_hdr_len = sizeof(*unicast_packet);
 225         int ucf_hdr_len = sizeof(*frag1);
 226         int data_len = skb->len - uc_hdr_len;
 227         int large_tail = 0, ret = NET_RX_DROP;
 228         uint16_t seqno;
 229
 230         primary_if = batadv_primary_if_get_selected(bat_priv);
 231         if (!primary_if)
 232                 goto dropped;
 233
 234         frag_skb = dev_alloc_skb(data_len - (data_len / 2) + ucf_hdr_len);
 235         if (!frag_skb)
 236                 goto dropped;
 237         skb_reserve(frag_skb, ucf_hdr_len);
 238
 239         unicast_packet = (struct unicast_packet *)skb->data;
 240         memcpy(&tmp_uc, unicast_packet, uc_hdr_len);
 241         skb_split(skb, frag_skb, data_len / 2 + uc_hdr_len);
 242
 243         if (batadv_skb_head_push(skb, ucf_hdr_len - uc_hdr_len) < 0 ||
 244             batadv_skb_head_push(frag_skb, ucf_hdr_len) < 0)
 245                 goto drop_frag;
 246
 247         frag1 = (struct unicast_frag_packet *)skb->data;
 248         frag2 = (struct unicast_frag_packet *)frag_skb->data;
 249
 250         memcpy(frag1, &tmp_uc, sizeof(tmp_uc));
 251
 252         frag1->header.ttl--;
 253         frag1->header.version = COMPAT_VERSION;
 254         frag1->header.packet_type = BAT_UNICAST_FRAG;
 255
 256         memcpy(frag1->orig, primary_if->net_dev->dev_addr, ETH_ALEN);
 257         memcpy(frag2, frag1, sizeof(*frag2));
 258
 259         if (data_len & 1)
 260                 large_tail = UNI_FRAG_LARGETAIL;
 261
 262         frag1->flags = UNI_FRAG_HEAD | large_tail;
 263         frag2->flags = large_tail;
 264
 265         seqno = atomic_add_return(2, &hard_iface->frag_seqno);
 266         frag1->seqno = htons(seqno - 1);
 267         frag2->seqno = htons(seqno);
 268
 269         batadv_send_skb_packet(skb, hard_iface, dstaddr);
 270         batadv_send_skb_packet(frag_skb, hard_iface, dstaddr);
 271         ret = NET_RX_SUCCESS;
 272         goto out;
 273
 274 drop_frag:
 275         kfree_skb(frag_skb);
 276 dropped:
 277         kfree_skb(skb);
 278 out:
 279         if (primary_if)
 280                 batadv_hardif_free_ref(primary_if);
 281         return ret;
 282 }
 283
 284 int batadv_unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv)
 285 {
 286         struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
 287         struct unicast_packet *unicast_packet;
 288         struct orig_node *orig_node;
 289         struct neigh_node *neigh_node;
 290         int data_len = skb->len;
 291         int ret = 1;
 292
 293         /* get routing information */
 294         if (is_multicast_ether_addr(ethhdr->h_dest)) {
 295                 orig_node = batadv_gw_get_selected_orig(bat_priv);
 296                 if (orig_node)
 297                         goto find_router;
 298         }
 299
 300         /* check for tt host - increases orig_node refcount.
 301          * returns NULL in case of AP isolation
 302          */
 303         orig_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
 304                                              ethhdr->h_dest);
 305 find_router:
 306         /* find_router():
 307          *  - if orig_node is NULL it returns NULL
 308          *  - increases neigh_nodes refcount if found.
 309          */
 310         neigh_node = batadv_find_router(bat_priv, orig_node, NULL);
 311         if (!neigh_node)
 312                 goto out;
 313
 314         if (batadv_skb_head_push(skb, sizeof(*unicast_packet)) < 0)
 315                 goto out;
 316
 317         unicast_packet = (struct unicast_packet *)skb->data;
 318
 319         unicast_packet->header.version = COMPAT_VERSION;
 320         /* batman packet type: unicast */
 321         unicast_packet->header.packet_type = BAT_UNICAST;
 322         /* set unicast ttl */
 323         unicast_packet->header.ttl = TTL;
 324         /* copy the destination for faster routing */
 325         memcpy(unicast_packet->dest, orig_node->orig, ETH_ALEN);
 326         /* set the destination tt version number */
 327         unicast_packet->ttvn =
 328                 (uint8_t)atomic_read(&orig_node->last_ttvn);
 329
 330         /* inform the destination node that we are still missing a correct route
 331          * for this client. The destination will receive this packet and will
 332          * try to reroute it because the ttvn contained in the header is less
 333          * than the current one
 334          */
 335         if (batadv_tt_global_client_is_roaming(bat_priv, ethhdr->h_dest))
 336                 unicast_packet->ttvn = unicast_packet->ttvn - 1;
 337
 338         if (atomic_read(&bat_priv->fragmentation) &&
 339             data_len + sizeof(*unicast_packet) >
 340                                 neigh_node->if_incoming->net_dev->mtu) {
 341                 /* send frag skb decreases ttl */
 342                 unicast_packet->header.ttl++;
 343                 ret = batadv_frag_send_skb(skb, bat_priv,
 344                                            neigh_node->if_incoming,
 345                                            neigh_node->addr);
 346                 goto out;
 347         }
 348
 349         batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
 350         ret = 0;
 351         goto out;
 352
 353 out:
 354         if (neigh_node)
 355                 batadv_neigh_node_free_ref(neigh_node);
 356         if (orig_node)
 357                 batadv_orig_node_free_ref(orig_node);
 358         if (ret == 1)
 359                 kfree_skb(skb);
 360         return ret;
 361 }