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