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         /* TODO:
  52          * if this package isn't ipv6 one, where should it be routed?
  53          */
  54         if (type != ETH_P_IPV6)
  55                 return 0;
  56
  57         /* intra-pan communication */
  58         info->saddr.pan_id = wpan_dev->pan_id;
  59         info->daddr.pan_id = info->saddr.pan_id;
  60
  61         if (!memcmp(daddr, ldev->broadcast, EUI64_ADDR_LEN)) {
  62                 info->daddr.short_addr = cpu_to_le16(IEEE802154_ADDR_BROADCAST);
  63                 info->daddr.mode = IEEE802154_ADDR_SHORT;
  64         } else {
  65                 __le16 short_addr = cpu_to_le16(IEEE802154_ADDR_SHORT_UNSPEC);
  66
  67                 n = neigh_lookup(&nd_tbl, &hdr->daddr, ldev);
  68                 if (n) {
  69                         llneigh = lowpan_802154_neigh(neighbour_priv(n));
  70                         read_lock_bh(&n->lock);
  71                         short_addr = llneigh->short_addr;
  72                         read_unlock_bh(&n->lock);
  73                 }
  74
  75                 if (llneigh &&
  76                     lowpan_802154_is_valid_src_short_addr(short_addr)) {
  77                         info->daddr.short_addr = short_addr;
  78                         info->daddr.mode = IEEE802154_ADDR_SHORT;
  79                 } else {
  80                         info->daddr.mode = IEEE802154_ADDR_LONG;
  81                         ieee802154_be64_to_le64(&info->daddr.extended_addr,
  82                                                 daddr);
  83                 }
  84
  85                 if (n)
  86                         neigh_release(n);
  87         }
  88
  89         if (!saddr) {
  90                 if (lowpan_802154_is_valid_src_short_addr(wpan_dev->short_addr)) {
  91                         info->saddr.mode = IEEE802154_ADDR_SHORT;
  92                         info->saddr.short_addr = wpan_dev->short_addr;
  93                 } else {
  94                         info->saddr.mode = IEEE802154_ADDR_LONG;
  95                         info->saddr.extended_addr = wpan_dev->extended_addr;
  96                 }
  97         } else {
  98                 info->saddr.mode = IEEE802154_ADDR_LONG;
  99                 ieee802154_be64_to_le64(&info->saddr.extended_addr, saddr);
 100         }
 101
 102         return 0;
 103 }
 104
 105 static struct sk_buff*
 106 lowpan_alloc_frag(struct sk_buff *skb, int size,
 107                   const struct ieee802154_hdr *master_hdr, bool frag1)
 108 {
 109         struct net_device *wdev = lowpan_802154_dev(skb->dev)->wdev;
 110         struct sk_buff *frag;
 111         int rc;
 112
 113         frag = alloc_skb(wdev->needed_headroom + wdev->needed_tailroom + size,
 114                          GFP_ATOMIC);
 115
 116         if (likely(frag)) {
 117                 frag->dev = wdev;
 118                 frag->priority = skb->priority;
 119                 skb_reserve(frag, wdev->needed_headroom);
 120                 skb_reset_network_header(frag);
 121                 *mac_cb(frag) = *mac_cb(skb);
 122
 123                 if (frag1) {
 124                         skb_put_data(frag, skb_mac_header(skb), skb->mac_len);
 125                 } else {
 126                         rc = wpan_dev_hard_header(frag, wdev,
 127                                                   &master_hdr->dest,
 128                                                   &master_hdr->source, size);
 129                         if (rc < 0) {
 130                                 kfree_skb(frag);
 131                                 return ERR_PTR(rc);
 132                         }
 133                 }
 134         } else {
 135                 frag = ERR_PTR(-ENOMEM);
 136         }
 137
 138         return frag;
 139 }
 140
 141 static int
 142 lowpan_xmit_fragment(struct sk_buff *skb, const struct ieee802154_hdr *wpan_hdr,
 143                      u8 *frag_hdr, int frag_hdrlen,
 144                      int offset, int len, bool frag1)
 145 {
 146         struct sk_buff *frag;
 147
 148         raw_dump_inline(__func__, " fragment header", frag_hdr, frag_hdrlen);
 149
 150         frag = lowpan_alloc_frag(skb, frag_hdrlen + len, wpan_hdr, frag1);
 151         if (IS_ERR(frag))
 152                 return PTR_ERR(frag);
 153
 154         skb_put_data(frag, frag_hdr, frag_hdrlen);
 155         skb_put_data(frag, skb_network_header(skb) + offset, len);
 156
 157         raw_dump_table(__func__, " fragment dump", frag->data, frag->len);
 158
 159         return dev_queue_xmit(frag);
 160 }
 161
 162 static int
 163 lowpan_xmit_fragmented(struct sk_buff *skb, struct net_device *ldev,
 164                        const struct ieee802154_hdr *wpan_hdr, u16 dgram_size,
 165                        u16 dgram_offset)
 166 {
 167         __be16 frag_tag;
 168         u8 frag_hdr[5];
 169         int frag_cap, frag_len, payload_cap, rc;
 170         int skb_unprocessed, skb_offset;
 171
 172         frag_tag = htons(lowpan_802154_dev(ldev)->fragment_tag);
 173         lowpan_802154_dev(ldev)->fragment_tag++;
 174
 175         frag_hdr[0] = LOWPAN_DISPATCH_FRAG1 | ((dgram_size >> 8) & 0x07);
 176         frag_hdr[1] = dgram_size & 0xff;
 177         memcpy(frag_hdr + 2, &frag_tag, sizeof(frag_tag));
 178
 179         payload_cap = ieee802154_max_payload(wpan_hdr);
 180
 181         frag_len = round_down(payload_cap - LOWPAN_FRAG1_HEAD_SIZE -
 182                               skb_network_header_len(skb), 8);
 183
 184         skb_offset = skb_network_header_len(skb);
 185         skb_unprocessed = skb->len - skb->mac_len - skb_offset;
 186
 187         rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
 188                                   LOWPAN_FRAG1_HEAD_SIZE, 0,
 189                                   frag_len + skb_network_header_len(skb),
 190                                   true);
 191         if (rc) {
 192                 pr_debug("%s unable to send FRAG1 packet (tag: %d)",
 193                          __func__, ntohs(frag_tag));
 194                 goto err;
 195         }
 196
 197         frag_hdr[0] &= ~LOWPAN_DISPATCH_FRAG1;
 198         frag_hdr[0] |= LOWPAN_DISPATCH_FRAGN;
 199         frag_cap = round_down(payload_cap - LOWPAN_FRAGN_HEAD_SIZE, 8);
 200
 201         do {
 202                 dgram_offset += frag_len;
 203                 skb_offset += frag_len;
 204                 skb_unprocessed -= frag_len;
 205                 frag_len = min(frag_cap, skb_unprocessed);
 206
 207                 frag_hdr[4] = dgram_offset >> 3;
 208
 209                 rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
 210                                           LOWPAN_FRAGN_HEAD_SIZE, skb_offset,
 211                                           frag_len, false);
 212                 if (rc) {
 213                         pr_debug("%s unable to send a FRAGN packet. (tag: %d, offset: %d)\n",
 214                                  __func__, ntohs(frag_tag), skb_offset);
 215                         goto err;
 216                 }
 217         } while (skb_unprocessed > frag_cap);
 218
 219         ldev->stats.tx_packets++;
 220         ldev->stats.tx_bytes += dgram_size;
 221         consume_skb(skb);
 222         return NET_XMIT_SUCCESS;
 223
 224 err:
 225         kfree_skb(skb);
 226         return rc;
 227 }
 228
 229 static int lowpan_header(struct sk_buff *skb, struct net_device *ldev,
 230                          u16 *dgram_size, u16 *dgram_offset)
 231 {
 232         struct wpan_dev *wpan_dev = lowpan_802154_dev(ldev)->wdev->ieee802154_ptr;
 233         struct ieee802154_mac_cb *cb = mac_cb_init(skb);
 234         struct lowpan_addr_info info;
 235
 236         memcpy(&info, lowpan_skb_priv(skb), sizeof(info));
 237
 238         *dgram_size = skb->len;
 239         lowpan_header_compress(skb, ldev, &info.daddr, &info.saddr);
 240         /* dgram_offset = (saved bytes after compression) + lowpan header len */
 241         *dgram_offset = (*dgram_size - skb->len) + skb_network_header_len(skb);
 242
 243         cb->type = IEEE802154_FC_TYPE_DATA;
 244
 245         if (info.daddr.mode == IEEE802154_ADDR_SHORT &&
 246             ieee802154_is_broadcast_short_addr(info.daddr.short_addr))
 247                 cb->ackreq = false;
 248         else
 249                 cb->ackreq = wpan_dev->ackreq;
 250
 251         return wpan_dev_hard_header(skb, lowpan_802154_dev(ldev)->wdev,
 252                                     &info.daddr, &info.saddr, 0);
 253 }
 254
 255 netdev_tx_t lowpan_xmit(struct sk_buff *skb, struct net_device *ldev)
 256 {
 257         struct ieee802154_hdr wpan_hdr;
 258         int max_single, ret;
 259         u16 dgram_size, dgram_offset;
 260
 261         pr_debug("package xmit\n");
 262
 263         WARN_ON_ONCE(skb->len > IPV6_MIN_MTU);
 264
 265         /* We must take a copy of the skb before we modify/replace the ipv6
 266          * header as the header could be used elsewhere
 267          */
 268         skb = skb_unshare(skb, GFP_ATOMIC);
 269         if (!skb)
 270                 return NET_XMIT_DROP;
 271
 272         ret = lowpan_header(skb, ldev, &dgram_size, &dgram_offset);
 273         if (ret < 0) {
 274                 kfree_skb(skb);
 275                 return NET_XMIT_DROP;
 276         }
 277
 278         if (ieee802154_hdr_peek(skb, &wpan_hdr) < 0) {
 279                 kfree_skb(skb);
 280                 return NET_XMIT_DROP;
 281         }
 282
 283         max_single = ieee802154_max_payload(&wpan_hdr);
 284
 285         if (skb_tail_pointer(skb) - skb_network_header(skb) <= max_single) {
 286                 skb->dev = lowpan_802154_dev(ldev)->wdev;
 287                 ldev->stats.tx_packets++;
 288                 ldev->stats.tx_bytes += dgram_size;
 289                 return dev_queue_xmit(skb);
 290         } else {
 291                 netdev_tx_t rc;
 292
 293                 pr_debug("frame is too big, fragmentation is needed\n");
 294                 rc = lowpan_xmit_fragmented(skb, ldev, &wpan_hdr, dgram_size,
 295                                             dgram_offset);
 296
 297                 return rc < 0 ? NET_XMIT_DROP : rc;
 298         }
 299 }