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                         skb_put_data(frag, skb_mac_header(skb), skb->mac_len);
 128                 } else {
 129                         rc = wpan_dev_hard_header(frag, wdev,
 130                                                   &master_hdr->dest,
 131                                                   &master_hdr->source, size);
 132                         if (rc < 0) {
 133                                 kfree_skb(frag);
 134                                 return ERR_PTR(rc);
 135                         }
 136                 }
 137         } else {
 138                 frag = ERR_PTR(-ENOMEM);
 139         }
 140
 141         return frag;
 142 }
 143
 144 static int
 145 lowpan_xmit_fragment(struct sk_buff *skb, const struct ieee802154_hdr *wpan_hdr,
 146                      u8 *frag_hdr, int frag_hdrlen,
 147                      int offset, int len, bool frag1)
 148 {
 149         struct sk_buff *frag;
 150
 151         raw_dump_inline(__func__, " fragment header", frag_hdr, frag_hdrlen);
 152
 153         frag = lowpan_alloc_frag(skb, frag_hdrlen + len, wpan_hdr, frag1);
 154         if (IS_ERR(frag))
 155                 return PTR_ERR(frag);
 156
 157         skb_put_data(frag, frag_hdr, frag_hdrlen);
 158         skb_put_data(frag, skb_network_header(skb) + offset, len);
 159
 160         raw_dump_table(__func__, " fragment dump", frag->data, frag->len);
 161
 162         return dev_queue_xmit(frag);
 163 }
 164
 165 static int
 166 lowpan_xmit_fragmented(struct sk_buff *skb, struct net_device *ldev,
 167                        const struct ieee802154_hdr *wpan_hdr, u16 dgram_size,
 168                        u16 dgram_offset)
 169 {
 170         __be16 frag_tag;
 171         u8 frag_hdr[5];
 172         int frag_cap, frag_len, payload_cap, rc;
 173         int skb_unprocessed, skb_offset;
 174
 175         frag_tag = htons(lowpan_802154_dev(ldev)->fragment_tag);
 176         lowpan_802154_dev(ldev)->fragment_tag++;
 177
 178         frag_hdr[0] = LOWPAN_DISPATCH_FRAG1 | ((dgram_size >> 8) & 0x07);
 179         frag_hdr[1] = dgram_size & 0xff;
 180         memcpy(frag_hdr + 2, &frag_tag, sizeof(frag_tag));
 181
 182         payload_cap = ieee802154_max_payload(wpan_hdr);
 183
 184         frag_len = round_down(payload_cap - LOWPAN_FRAG1_HEAD_SIZE -
 185                               skb_network_header_len(skb), 8);
 186
 187         skb_offset = skb_network_header_len(skb);
 188         skb_unprocessed = skb->len - skb->mac_len - skb_offset;
 189
 190         rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
 191                                   LOWPAN_FRAG1_HEAD_SIZE, 0,
 192                                   frag_len + skb_network_header_len(skb),
 193                                   true);
 194         if (rc) {
 195                 pr_debug("%s unable to send FRAG1 packet (tag: %d)",
 196                          __func__, ntohs(frag_tag));
 197                 goto err;
 198         }
 199
 200         frag_hdr[0] &= ~LOWPAN_DISPATCH_FRAG1;
 201         frag_hdr[0] |= LOWPAN_DISPATCH_FRAGN;
 202         frag_cap = round_down(payload_cap - LOWPAN_FRAGN_HEAD_SIZE, 8);
 203
 204         do {
 205                 dgram_offset += frag_len;
 206                 skb_offset += frag_len;
 207                 skb_unprocessed -= frag_len;
 208                 frag_len = min(frag_cap, skb_unprocessed);
 209
 210                 frag_hdr[4] = dgram_offset >> 3;
 211
 212                 rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
 213                                           LOWPAN_FRAGN_HEAD_SIZE, skb_offset,
 214                                           frag_len, false);
 215                 if (rc) {
 216                         pr_debug("%s unable to send a FRAGN packet. (tag: %d, offset: %d)\n",
 217                                  __func__, ntohs(frag_tag), skb_offset);
 218                         goto err;
 219                 }
 220         } while (skb_unprocessed > frag_cap);
 221
 222         ldev->stats.tx_packets++;
 223         ldev->stats.tx_bytes += dgram_size;
 224         consume_skb(skb);
 225         return NET_XMIT_SUCCESS;
 226
 227 err:
 228         kfree_skb(skb);
 229         return rc;
 230 }
 231
 232 static int lowpan_header(struct sk_buff *skb, struct net_device *ldev,
 233                          u16 *dgram_size, u16 *dgram_offset)
 234 {
 235         struct wpan_dev *wpan_dev = lowpan_802154_dev(ldev)->wdev->ieee802154_ptr;
 236         struct ieee802154_mac_cb *cb = mac_cb_init(skb);
 237         struct lowpan_addr_info info;
 238
 239         memcpy(&info, lowpan_skb_priv(skb), sizeof(info));
 240
 241         *dgram_size = skb->len;
 242         lowpan_header_compress(skb, ldev, &info.daddr, &info.saddr);
 243         /* dgram_offset = (saved bytes after compression) + lowpan header len */
 244         *dgram_offset = (*dgram_size - skb->len) + skb_network_header_len(skb);
 245
 246         cb->type = IEEE802154_FC_TYPE_DATA;
 247
 248         if (info.daddr.mode == IEEE802154_ADDR_SHORT &&
 249             ieee802154_is_broadcast_short_addr(info.daddr.short_addr))
 250                 cb->ackreq = false;
 251         else
 252                 cb->ackreq = wpan_dev->ackreq;
 253
 254         return wpan_dev_hard_header(skb, lowpan_802154_dev(ldev)->wdev,
 255                                     &info.daddr, &info.saddr, 0);
 256 }
 257
 258 netdev_tx_t lowpan_xmit(struct sk_buff *skb, struct net_device *ldev)
 259 {
 260         struct ieee802154_hdr wpan_hdr;
 261         int max_single, ret;
 262         u16 dgram_size, dgram_offset;
 263
 264         pr_debug("package xmit\n");
 265
 266         WARN_ON_ONCE(skb->len > IPV6_MIN_MTU);
 267
 268         /* We must take a copy of the skb before we modify/replace the ipv6
 269          * header as the header could be used elsewhere
 270          */
 271         if (unlikely(skb_headroom(skb) < ldev->needed_headroom ||
 272                      skb_tailroom(skb) < ldev->needed_tailroom)) {
 273                 struct sk_buff *nskb;
 274
 275                 nskb = skb_copy_expand(skb, ldev->needed_headroom,
 276                                        ldev->needed_tailroom, GFP_ATOMIC);
 277                 if (likely(nskb)) {
 278                         consume_skb(skb);
 279                         skb = nskb;
 280                 } else {
 281                         kfree_skb(skb);
 282                         return NET_XMIT_DROP;
 283                 }
 284         } else {
 285                 skb = skb_unshare(skb, GFP_ATOMIC);
 286                 if (!skb)
 287                         return NET_XMIT_DROP;
 288         }
 289
 290         ret = lowpan_header(skb, ldev, &dgram_size, &dgram_offset);
 291         if (ret < 0) {
 292                 kfree_skb(skb);
 293                 return NET_XMIT_DROP;
 294         }
 295
 296         if (ieee802154_hdr_peek(skb, &wpan_hdr) < 0) {
 297                 kfree_skb(skb);
 298                 return NET_XMIT_DROP;
 299         }
 300
 301         max_single = ieee802154_max_payload(&wpan_hdr);
 302
 303         if (skb_tail_pointer(skb) - skb_network_header(skb) <= max_single) {
 304                 skb->dev = lowpan_802154_dev(ldev)->wdev;
 305                 ldev->stats.tx_packets++;
 306                 ldev->stats.tx_bytes += dgram_size;
 307                 return dev_queue_xmit(skb);
 308         } else {
 309                 netdev_tx_t rc;
 310
 311                 pr_debug("frame is too big, fragmentation is needed\n");
 312                 rc = lowpan_xmit_fragmented(skb, ldev, &wpan_hdr, dgram_size,
 313                                             dgram_offset);
 314
 315                 return rc < 0 ? NET_XMIT_DROP : rc;
 316         }
 317 }