linux/net/batman-adv/unicast.c
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   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
  32static struct sk_buff *
  33batadv_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
  74err:
  75        /* free buffered skb, skb will be freed later */
  76        kfree_skb(tfp->skb);
  77        return NULL;
  78}
  79
  80static 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
  98static 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
 118static struct batadv_frag_packet_list_entry *
 119batadv_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
 152mov_tail:
 153        list_move_tail(&tfp->list, head);
 154        return NULL;
 155}
 156
 157void 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 */
 178int 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
 217out:
 218        if (orig_node)
 219                batadv_orig_node_free_ref(orig_node);
 220        return ret;
 221}
 222
 223int 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
 281drop_frag:
 282        kfree_skb(frag_skb);
 283dropped:
 284        kfree_skb(skb);
 285out:
 286        if (primary_if)
 287                batadv_hardif_free_ref(primary_if);
 288        return ret;
 289}
 290
 291int 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
 314find_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
 363out:
 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}
 372
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