net/ieee802154/6lowpan/tx.c

   1 /* This program is free software; you can redistribute it and/or modify
   2  * it under the terms of the GNU General Public License version 2
   3  * as published by the Free Software Foundation.
   4  *
   5  * This program is distributed in the hope that it will be useful,
   6  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   7  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   8  * GNU General Public License for more details.
   9  */
  10
  11 #include <net/6lowpan.h>
  12 #include <net/ndisc.h>
  13 #include <net/ieee802154_netdev.h>
  14 #include <net/mac802154.h>
  15
  16 #include "6lowpan_i.h"
  17
  18 #define LOWPAN_FRAG1_HEAD_SIZE  0x4
  19 #define LOWPAN_FRAGN_HEAD_SIZE  0x5
  20
  21 struct lowpan_addr_info {
  22         struct ieee802154_addr daddr;
  23         struct ieee802154_addr saddr;
  24 };
  25
  26 static inline struct
  27 lowpan_addr_info *lowpan_skb_priv(const struct sk_buff *skb)
  28 {
  29         WARN_ON_ONCE(skb_headroom(skb) < sizeof(struct lowpan_addr_info));
  30         return (struct lowpan_addr_info *)(skb->data -
  31                         sizeof(struct lowpan_addr_info));
  32 }
  33
  34 /* This callback will be called from AF_PACKET and IPv6 stack, the AF_PACKET
  35  * sockets gives an 8 byte array for addresses only!
  36  *
  37  * TODO I think AF_PACKET DGRAM (sending/receiving) RAW (sending) makes no
  38  * sense here. We should disable it, the right use-case would be AF_INET6
  39  * RAW/DGRAM sockets.
  40  */
  41 int lowpan_header_create(struct sk_buff *skb, struct net_device *ldev,
  42                          unsigned short type, const void *daddr,
  43                          const void *saddr, unsigned int len)
  44 {
  45         struct wpan_dev *wpan_dev = lowpan_802154_dev(ldev)->wdev->ieee802154_ptr;
  46         struct lowpan_addr_info *info = lowpan_skb_priv(skb);
  47         struct lowpan_802154_neigh *llneigh = NULL;
  48         const struct ipv6hdr *hdr = ipv6_hdr(skb);
  49         struct neighbour *n;
  50
  51         if (!daddr)
  52                 return -EINVAL;
  53
  54         /* TODO:
  55          * if this package isn't ipv6 one, where should it be routed?
  56          */
  57         if (type != ETH_P_IPV6)
  58                 return 0;
  59
  60         /* intra-pan communication */
  61         info->saddr.pan_id = wpan_dev->pan_id;
  62         info->daddr.pan_id = info->saddr.pan_id;
  63
  64         if (!memcmp(daddr, ldev->broadcast, EUI64_ADDR_LEN)) {
  65                 info->daddr.short_addr = cpu_to_le16(IEEE802154_ADDR_BROADCAST);
  66                 info->daddr.mode = IEEE802154_ADDR_SHORT;
  67         } else {
  68                 __le16 short_addr = cpu_to_le16(IEEE802154_ADDR_SHORT_UNSPEC);
  69
  70                 n = neigh_lookup(&nd_tbl, &hdr->daddr, ldev);
  71                 if (n) {
  72                         llneigh = lowpan_802154_neigh(neighbour_priv(n));
  73                         read_lock_bh(&n->lock);
  74                         short_addr = llneigh->short_addr;
  75                         read_unlock_bh(&n->lock);
  76                 }
  77
  78                 if (llneigh &&
  79                     lowpan_802154_is_valid_src_short_addr(short_addr)) {
  80                         info->daddr.short_addr = short_addr;
  81                         info->daddr.mode = IEEE802154_ADDR_SHORT;
  82                 } else {
  83                         info->daddr.mode = IEEE802154_ADDR_LONG;
  84                         ieee802154_be64_to_le64(&info->daddr.extended_addr,
  85                                                 daddr);
  86                 }
  87
  88                 if (n)
  89                         neigh_release(n);
  90         }
  91
  92         if (!saddr) {
  93                 if (lowpan_802154_is_valid_src_short_addr(wpan_dev->short_addr)) {
  94                         info->saddr.mode = IEEE802154_ADDR_SHORT;
  95                         info->saddr.short_addr = wpan_dev->short_addr;
  96                 } else {
  97                         info->saddr.mode = IEEE802154_ADDR_LONG;
  98                         info->saddr.extended_addr = wpan_dev->extended_addr;
  99                 }
 100         } else {
 101                 info->saddr.mode = IEEE802154_ADDR_LONG;
 102                 ieee802154_be64_to_le64(&info->saddr.extended_addr, saddr);
 103         }
 104
 105         return 0;
 106 }
 107
 108 static struct sk_buff*
 109 lowpan_alloc_frag(struct sk_buff *skb, int size,
 110                   const struct ieee802154_hdr *master_hdr, bool frag1)
 111 {
 112         struct net_device *wdev = lowpan_802154_dev(skb->dev)->wdev;
 113         struct sk_buff *frag;
 114         int rc;
 115
 116         frag = alloc_skb(wdev->needed_headroom + wdev->needed_tailroom + size,
 117                          GFP_ATOMIC);
 118
 119         if (likely(frag)) {
 120                 frag->dev = wdev;
 121                 frag->priority = skb->priority;
 122                 skb_reserve(frag, wdev->needed_headroom);
 123                 skb_reset_network_header(frag);
 124                 *mac_cb(frag) = *mac_cb(skb);
 125
 126                 if (frag1) {
 127                         memcpy(skb_put(frag, skb->mac_len),
 128                                skb_mac_header(skb), skb->mac_len);
 129                 } else {
 130                         rc = wpan_dev_hard_header(frag, wdev,
 131                                                   &master_hdr->dest,
 132                                                   &master_hdr->source, size);
 133                         if (rc < 0) {
 134                                 kfree_skb(frag);
 135                                 return ERR_PTR(rc);
 136                         }
 137                 }
 138         } else {
 139                 frag = ERR_PTR(-ENOMEM);
 140         }
 141
 142         return frag;
 143 }
 144
 145 static int
 146 lowpan_xmit_fragment(struct sk_buff *skb, const struct ieee802154_hdr *wpan_hdr,
 147                      u8 *frag_hdr, int frag_hdrlen,
 148                      int offset, int len, bool frag1)
 149 {
 150         struct sk_buff *frag;
 151
 152         raw_dump_inline(__func__, " fragment header", frag_hdr, frag_hdrlen);
 153
 154         frag = lowpan_alloc_frag(skb, frag_hdrlen + len, wpan_hdr, frag1);
 155         if (IS_ERR(frag))
 156                 return PTR_ERR(frag);
 157
 158         memcpy(skb_put(frag, frag_hdrlen), frag_hdr, frag_hdrlen);
 159         memcpy(skb_put(frag, len), skb_network_header(skb) + offset, len);
 160
 161         raw_dump_table(__func__, " fragment dump", frag->data, frag->len);
 162
 163         return dev_queue_xmit(frag);
 164 }
 165
 166 static int
 167 lowpan_xmit_fragmented(struct sk_buff *skb, struct net_device *ldev,
 168                        const struct ieee802154_hdr *wpan_hdr, u16 dgram_size,
 169                        u16 dgram_offset)
 170 {
 171         __be16 frag_tag;
 172         u8 frag_hdr[5];
 173         int frag_cap, frag_len, payload_cap, rc;
 174         int skb_unprocessed, skb_offset;
 175
 176         frag_tag = htons(lowpan_802154_dev(ldev)->fragment_tag);
 177         lowpan_802154_dev(ldev)->fragment_tag++;
 178
 179         frag_hdr[0] = LOWPAN_DISPATCH_FRAG1 | ((dgram_size >> 8) & 0x07);
 180         frag_hdr[1] = dgram_size & 0xff;
 181         memcpy(frag_hdr + 2, &frag_tag, sizeof(frag_tag));
 182
 183         payload_cap = ieee802154_max_payload(wpan_hdr);
 184
 185         frag_len = round_down(payload_cap - LOWPAN_FRAG1_HEAD_SIZE -
 186                               skb_network_header_len(skb), 8);
 187
 188         skb_offset = skb_network_header_len(skb);
 189         skb_unprocessed = skb->len - skb->mac_len - skb_offset;
 190
 191         rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
 192                                   LOWPAN_FRAG1_HEAD_SIZE, 0,
 193                                   frag_len + skb_network_header_len(skb),
 194                                   true);
 195         if (rc) {
 196                 pr_debug("%s unable to send FRAG1 packet (tag: %d)",
 197                          __func__, ntohs(frag_tag));
 198                 goto err;
 199         }
 200
 201         frag_hdr[0] &= ~LOWPAN_DISPATCH_FRAG1;
 202         frag_hdr[0] |= LOWPAN_DISPATCH_FRAGN;
 203         frag_cap = round_down(payload_cap - LOWPAN_FRAGN_HEAD_SIZE, 8);
 204
 205         do {
 206                 dgram_offset += frag_len;
 207                 skb_offset += frag_len;
 208                 skb_unprocessed -= frag_len;
 209                 frag_len = min(frag_cap, skb_unprocessed);
 210
 211                 frag_hdr[4] = dgram_offset >> 3;
 212
 213                 rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
 214                                           LOWPAN_FRAGN_HEAD_SIZE, skb_offset,
 215                                           frag_len, false);
 216                 if (rc) {
 217                         pr_debug("%s unable to send a FRAGN packet. (tag: %d, offset: %d)\n",
 218                                  __func__, ntohs(frag_tag), skb_offset);
 219                         goto err;
 220                 }
 221         } while (skb_unprocessed > frag_cap);
 222
 223         ldev->stats.tx_packets++;
 224         ldev->stats.tx_bytes += dgram_size;
 225         consume_skb(skb);
 226         return NET_XMIT_SUCCESS;
 227
 228 err:
 229         kfree_skb(skb);
 230         return rc;
 231 }
 232
 233 static int lowpan_header(struct sk_buff *skb, struct net_device *ldev,
 234                          u16 *dgram_size, u16 *dgram_offset)
 235 {
 236         struct wpan_dev *wpan_dev = lowpan_802154_dev(ldev)->wdev->ieee802154_ptr;
 237         struct ieee802154_mac_cb *cb = mac_cb_init(skb);
 238         struct lowpan_addr_info info;
 239
 240         memcpy(&info, lowpan_skb_priv(skb), sizeof(info));
 241
 242         *dgram_size = skb->len;
 243         lowpan_header_compress(skb, ldev, &info.daddr, &info.saddr);
 244         /* dgram_offset = (saved bytes after compression) + lowpan header len */
 245         *dgram_offset = (*dgram_size - skb->len) + skb_network_header_len(skb);
 246
 247         cb->type = IEEE802154_FC_TYPE_DATA;
 248
 249         if (info.daddr.mode == IEEE802154_ADDR_SHORT &&
 250             ieee802154_is_broadcast_short_addr(info.daddr.short_addr))
 251                 cb->ackreq = false;
 252         else
 253                 cb->ackreq = wpan_dev->ackreq;
 254
 255         return wpan_dev_hard_header(skb, lowpan_802154_dev(ldev)->wdev,
 256                                     &info.daddr, &info.saddr, 0);
 257 }
 258
 259 netdev_tx_t lowpan_xmit(struct sk_buff *skb, struct net_device *ldev)
 260 {
 261         struct ieee802154_hdr wpan_hdr;
 262         int max_single, ret;
 263         u16 dgram_size, dgram_offset;
 264
 265         pr_debug("package xmit\n");
 266
 267         WARN_ON_ONCE(skb->len > IPV6_MIN_MTU);
 268
 269         /* We must take a copy of the skb before we modify/replace the ipv6
 270          * header as the header could be used elsewhere
 271          */
 272         if (unlikely(skb_headroom(skb) < ldev->needed_headroom ||
 273                      skb_tailroom(skb) < ldev->needed_tailroom)) {
 274                 struct sk_buff *nskb;
 275
 276                 nskb = skb_copy_expand(skb, ldev->needed_headroom,
 277                                        ldev->needed_tailroom, GFP_ATOMIC);
 278                 if (likely(nskb)) {
 279                         consume_skb(skb);
 280                         skb = nskb;
 281                 } else {
 282                         kfree_skb(skb);
 283                         return NET_XMIT_DROP;
 284                 }
 285         } else {
 286                 skb = skb_unshare(skb, GFP_ATOMIC);
 287                 if (!skb)
 288                         return NET_XMIT_DROP;
 289         }
 290
 291         ret = lowpan_header(skb, ldev, &dgram_size, &dgram_offset);
 292         if (ret < 0) {
 293                 kfree_skb(skb);
 294                 return NET_XMIT_DROP;
 295         }
 296
 297         if (ieee802154_hdr_peek(skb, &wpan_hdr) < 0) {
 298                 kfree_skb(skb);
 299                 return NET_XMIT_DROP;
 300         }
 301
 302         max_single = ieee802154_max_payload(&wpan_hdr);
 303
 304         if (skb_tail_pointer(skb) - skb_network_header(skb) <= max_single) {
 305                 skb->dev = lowpan_802154_dev(ldev)->wdev;
 306                 ldev->stats.tx_packets++;
 307                 ldev->stats.tx_bytes += dgram_size;
 308                 return dev_queue_xmit(skb);
 309         } else {
 310                 netdev_tx_t rc;
 311
 312                 pr_debug("frame is too big, fragmentation is needed\n");
 313                 rc = lowpan_xmit_fragmented(skb, ldev, &wpan_hdr, dgram_size,
 314                                             dgram_offset);
 315
 316                 return rc < 0 ? NET_XMIT_DROP : rc;
 317         }
 318 }