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        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
  75err:
  76        /* free buffered skb, skb will be freed later */
  77        kfree_skb(tfp->skb);
  78        return NULL;
  79}
  80
  81static 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
  99static 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
 119static struct batadv_frag_packet_list_entry *
 120batadv_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
 155mov_tail:
 156        list_move_tail(&tfp->list, head);
 157        return NULL;
 158}
 159
 160void 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 */
 181int 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
 220out:
 221        if (orig_node)
 222                batadv_orig_node_free_ref(orig_node);
 223        return ret;
 224}
 225
 226int 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
 284drop_frag:
 285        kfree_skb(frag_skb);
 286dropped:
 287        kfree_skb(skb);
 288out:
 289        if (primary_if)
 290                batadv_hardif_free_ref(primary_if);
 291        return ret;
 292}
 293
 294int 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
 317find_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
 365out:
 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}
 374
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