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/ieee802154_netdev.h>
  13 #include <net/mac802154.h>
  14
  15 #include "6lowpan_i.h"
  16
  17 /* don't save pan id, it's intra pan */
  18 struct lowpan_addr {
  19         u8 mode;
  20         union {
  21                 /* IPv6 needs big endian here */
  22                 __be64 extended_addr;
  23                 __be16 short_addr;
  24         } u;
  25 };
  26
  27 struct lowpan_addr_info {
  28         struct lowpan_addr daddr;
  29         struct lowpan_addr saddr;
  30 };
  31
  32 static inline struct
  33 lowpan_addr_info *lowpan_skb_priv(const struct sk_buff *skb)
  34 {
  35         WARN_ON_ONCE(skb_headroom(skb) < sizeof(struct lowpan_addr_info));
  36         return (struct lowpan_addr_info *)(skb->data -
  37                         sizeof(struct lowpan_addr_info));
  38 }
  39
  40 /* This callback will be called from AF_PACKET and IPv6 stack, the AF_PACKET
  41  * sockets gives an 8 byte array for addresses only!
  42  *
  43  * TODO I think AF_PACKET DGRAM (sending/receiving) RAW (sending) makes no
  44  * sense here. We should disable it, the right use-case would be AF_INET6
  45  * RAW/DGRAM sockets.
  46  */
  47 int lowpan_header_create(struct sk_buff *skb, struct net_device *ldev,
  48                          unsigned short type, const void *_daddr,
  49                          const void *_saddr, unsigned int len)
  50 {
  51         const u8 *saddr = _saddr;
  52         const u8 *daddr = _daddr;
  53         struct lowpan_addr_info *info;
  54
  55         /* TODO:
  56          * if this package isn't ipv6 one, where should it be routed?
  57          */
  58         if (type != ETH_P_IPV6)
  59                 return 0;
  60
  61         if (!saddr)
  62                 saddr = ldev->dev_addr;
  63
  64         raw_dump_inline(__func__, "saddr", (unsigned char *)saddr, 8);
  65         raw_dump_inline(__func__, "daddr", (unsigned char *)daddr, 8);
  66
  67         info = lowpan_skb_priv(skb);
  68
  69         /* TODO: Currently we only support extended_addr */
  70         info->daddr.mode = IEEE802154_ADDR_LONG;
  71         memcpy(&info->daddr.u.extended_addr, daddr,
  72                sizeof(info->daddr.u.extended_addr));
  73         info->saddr.mode = IEEE802154_ADDR_LONG;
  74         memcpy(&info->saddr.u.extended_addr, saddr,
  75                sizeof(info->daddr.u.extended_addr));
  76
  77         return 0;
  78 }
  79
  80 static struct sk_buff*
  81 lowpan_alloc_frag(struct sk_buff *skb, int size,
  82                   const struct ieee802154_hdr *master_hdr, bool frag1)
  83 {
  84         struct net_device *wdev = lowpan_dev_info(skb->dev)->wdev;
  85         struct sk_buff *frag;
  86         int rc;
  87
  88         frag = alloc_skb(wdev->needed_headroom + wdev->needed_tailroom + size,
  89                          GFP_ATOMIC);
  90
  91         if (likely(frag)) {
  92                 frag->dev = wdev;
  93                 frag->priority = skb->priority;
  94                 skb_reserve(frag, wdev->needed_headroom);
  95                 skb_reset_network_header(frag);
  96                 *mac_cb(frag) = *mac_cb(skb);
  97
  98                 if (frag1) {
  99                         memcpy(skb_put(frag, skb->mac_len),
 100                                skb_mac_header(skb), skb->mac_len);
 101                 } else {
 102                         rc = wpan_dev_hard_header(frag, wdev,
 103                                                   &master_hdr->dest,
 104                                                   &master_hdr->source, size);
 105                         if (rc < 0) {
 106                                 kfree_skb(frag);
 107                                 return ERR_PTR(rc);
 108                         }
 109                 }
 110         } else {
 111                 frag = ERR_PTR(-ENOMEM);
 112         }
 113
 114         return frag;
 115 }
 116
 117 static int
 118 lowpan_xmit_fragment(struct sk_buff *skb, const struct ieee802154_hdr *wpan_hdr,
 119                      u8 *frag_hdr, int frag_hdrlen,
 120                      int offset, int len, bool frag1)
 121 {
 122         struct sk_buff *frag;
 123
 124         raw_dump_inline(__func__, " fragment header", frag_hdr, frag_hdrlen);
 125
 126         frag = lowpan_alloc_frag(skb, frag_hdrlen + len, wpan_hdr, frag1);
 127         if (IS_ERR(frag))
 128                 return PTR_ERR(frag);
 129
 130         memcpy(skb_put(frag, frag_hdrlen), frag_hdr, frag_hdrlen);
 131         memcpy(skb_put(frag, len), skb_network_header(skb) + offset, len);
 132
 133         raw_dump_table(__func__, " fragment dump", frag->data, frag->len);
 134
 135         return dev_queue_xmit(frag);
 136 }
 137
 138 static int
 139 lowpan_xmit_fragmented(struct sk_buff *skb, struct net_device *ldev,
 140                        const struct ieee802154_hdr *wpan_hdr, u16 dgram_size,
 141                        u16 dgram_offset)
 142 {
 143         __be16 frag_tag;
 144         u8 frag_hdr[5];
 145         int frag_cap, frag_len, payload_cap, rc;
 146         int skb_unprocessed, skb_offset;
 147
 148         frag_tag = htons(lowpan_dev_info(ldev)->fragment_tag);
 149         lowpan_dev_info(ldev)->fragment_tag++;
 150
 151         frag_hdr[0] = LOWPAN_DISPATCH_FRAG1 | ((dgram_size >> 8) & 0x07);
 152         frag_hdr[1] = dgram_size & 0xff;
 153         memcpy(frag_hdr + 2, &frag_tag, sizeof(frag_tag));
 154
 155         payload_cap = ieee802154_max_payload(wpan_hdr);
 156
 157         frag_len = round_down(payload_cap - LOWPAN_FRAG1_HEAD_SIZE -
 158                               skb_network_header_len(skb), 8);
 159
 160         skb_offset = skb_network_header_len(skb);
 161         skb_unprocessed = skb->len - skb->mac_len - skb_offset;
 162
 163         rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
 164                                   LOWPAN_FRAG1_HEAD_SIZE, 0,
 165                                   frag_len + skb_network_header_len(skb),
 166                                   true);
 167         if (rc) {
 168                 pr_debug("%s unable to send FRAG1 packet (tag: %d)",
 169                          __func__, ntohs(frag_tag));
 170                 goto err;
 171         }
 172
 173         frag_hdr[0] &= ~LOWPAN_DISPATCH_FRAG1;
 174         frag_hdr[0] |= LOWPAN_DISPATCH_FRAGN;
 175         frag_cap = round_down(payload_cap - LOWPAN_FRAGN_HEAD_SIZE, 8);
 176
 177         do {
 178                 dgram_offset += frag_len;
 179                 skb_offset += frag_len;
 180                 skb_unprocessed -= frag_len;
 181                 frag_len = min(frag_cap, skb_unprocessed);
 182
 183                 frag_hdr[4] = dgram_offset >> 3;
 184
 185                 rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
 186                                           LOWPAN_FRAGN_HEAD_SIZE, skb_offset,
 187                                           frag_len, false);
 188                 if (rc) {
 189                         pr_debug("%s unable to send a FRAGN packet. (tag: %d, offset: %d)\n",
 190                                  __func__, ntohs(frag_tag), skb_offset);
 191                         goto err;
 192                 }
 193         } while (skb_unprocessed > frag_cap);
 194
 195         ldev->stats.tx_packets++;
 196         ldev->stats.tx_bytes += dgram_size;
 197         consume_skb(skb);
 198         return NET_XMIT_SUCCESS;
 199
 200 err:
 201         kfree_skb(skb);
 202         return rc;
 203 }
 204
 205 static int lowpan_header(struct sk_buff *skb, struct net_device *ldev,
 206                          u16 *dgram_size, u16 *dgram_offset)
 207 {
 208         struct wpan_dev *wpan_dev = lowpan_dev_info(ldev)->wdev->ieee802154_ptr;
 209         struct ieee802154_addr sa, da;
 210         struct ieee802154_mac_cb *cb = mac_cb_init(skb);
 211         struct lowpan_addr_info info;
 212         void *daddr, *saddr;
 213
 214         memcpy(&info, lowpan_skb_priv(skb), sizeof(info));
 215
 216         /* TODO: Currently we only support extended_addr */
 217         daddr = &info.daddr.u.extended_addr;
 218         saddr = &info.saddr.u.extended_addr;
 219
 220         *dgram_size = skb->len;
 221         lowpan_header_compress(skb, ldev, ETH_P_IPV6, daddr, saddr, skb->len);
 222         /* dgram_offset = (saved bytes after compression) + lowpan header len */
 223         *dgram_offset = (*dgram_size - skb->len) + skb_network_header_len(skb);
 224
 225         cb->type = IEEE802154_FC_TYPE_DATA;
 226
 227         /* prepare wpan address data */
 228         sa.mode = IEEE802154_ADDR_LONG;
 229         sa.pan_id = wpan_dev->pan_id;
 230         sa.extended_addr = ieee802154_devaddr_from_raw(saddr);
 231
 232         /* intra-PAN communications */
 233         da.pan_id = sa.pan_id;
 234
 235         /* if the destination address is the broadcast address, use the
 236          * corresponding short address
 237          */
 238         if (lowpan_is_addr_broadcast((const u8 *)daddr)) {
 239                 da.mode = IEEE802154_ADDR_SHORT;
 240                 da.short_addr = cpu_to_le16(IEEE802154_ADDR_BROADCAST);
 241                 cb->ackreq = false;
 242         } else {
 243                 da.mode = IEEE802154_ADDR_LONG;
 244                 da.extended_addr = ieee802154_devaddr_from_raw(daddr);
 245                 cb->ackreq = wpan_dev->ackreq;
 246         }
 247
 248         return wpan_dev_hard_header(skb, lowpan_dev_info(ldev)->wdev, &da, &sa,
 249                                     0);
 250 }
 251
 252 netdev_tx_t lowpan_xmit(struct sk_buff *skb, struct net_device *ldev)
 253 {
 254         struct ieee802154_hdr wpan_hdr;
 255         int max_single, ret;
 256         u16 dgram_size, dgram_offset;
 257
 258         pr_debug("package xmit\n");
 259
 260         WARN_ON_ONCE(skb->len > IPV6_MIN_MTU);
 261
 262         /* We must take a copy of the skb before we modify/replace the ipv6
 263          * header as the header could be used elsewhere
 264          */
 265         skb = skb_unshare(skb, GFP_ATOMIC);
 266         if (!skb)
 267                 return NET_XMIT_DROP;
 268
 269         ret = lowpan_header(skb, ldev, &dgram_size, &dgram_offset);
 270         if (ret < 0) {
 271                 kfree_skb(skb);
 272                 return NET_XMIT_DROP;
 273         }
 274
 275         if (ieee802154_hdr_peek(skb, &wpan_hdr) < 0) {
 276                 kfree_skb(skb);
 277                 return NET_XMIT_DROP;
 278         }
 279
 280         max_single = ieee802154_max_payload(&wpan_hdr);
 281
 282         if (skb_tail_pointer(skb) - skb_network_header(skb) <= max_single) {
 283                 skb->dev = lowpan_dev_info(ldev)->wdev;
 284                 ldev->stats.tx_packets++;
 285                 ldev->stats.tx_bytes += dgram_size;
 286                 return dev_queue_xmit(skb);
 287         } else {
 288                 netdev_tx_t rc;
 289
 290                 pr_debug("frame is too big, fragmentation is needed\n");
 291                 rc = lowpan_xmit_fragmented(skb, ldev, &wpan_hdr, dgram_size,
 292                                             dgram_offset);
 293
 294                 return rc < 0 ? NET_XMIT_DROP : rc;
 295         }
 296 }