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 #define LOWPAN_FRAG1_HEAD_SIZE  0x4
  18 #define LOWPAN_FRAGN_HEAD_SIZE  0x5
  19
  20 /* don't save pan id, it's intra pan */
  21 struct lowpan_addr {
  22         u8 mode;
  23         union {
  24                 /* IPv6 needs big endian here */
  25                 __be64 extended_addr;
  26                 __be16 short_addr;
  27         } u;
  28 };
  29
  30 struct lowpan_addr_info {
  31         struct lowpan_addr daddr;
  32         struct lowpan_addr saddr;
  33 };
  34
  35 static inline struct
  36 lowpan_addr_info *lowpan_skb_priv(const struct sk_buff *skb)
  37 {
  38         WARN_ON_ONCE(skb_headroom(skb) < sizeof(struct lowpan_addr_info));
  39         return (struct lowpan_addr_info *)(skb->data -
  40                         sizeof(struct lowpan_addr_info));
  41 }
  42
  43 /* This callback will be called from AF_PACKET and IPv6 stack, the AF_PACKET
  44  * sockets gives an 8 byte array for addresses only!
  45  *
  46  * TODO I think AF_PACKET DGRAM (sending/receiving) RAW (sending) makes no
  47  * sense here. We should disable it, the right use-case would be AF_INET6
  48  * RAW/DGRAM sockets.
  49  */
  50 int lowpan_header_create(struct sk_buff *skb, struct net_device *ldev,
  51                          unsigned short type, const void *_daddr,
  52                          const void *_saddr, unsigned int len)
  53 {
  54         const u8 *saddr = _saddr;
  55         const u8 *daddr = _daddr;
  56         struct lowpan_addr_info *info;
  57
  58         /* TODO:
  59          * if this package isn't ipv6 one, where should it be routed?
  60          */
  61         if (type != ETH_P_IPV6)
  62                 return 0;
  63
  64         if (!saddr)
  65                 saddr = ldev->dev_addr;
  66
  67         raw_dump_inline(__func__, "saddr", (unsigned char *)saddr, 8);
  68         raw_dump_inline(__func__, "daddr", (unsigned char *)daddr, 8);
  69
  70         info = lowpan_skb_priv(skb);
  71
  72         /* TODO: Currently we only support extended_addr */
  73         info->daddr.mode = IEEE802154_ADDR_LONG;
  74         memcpy(&info->daddr.u.extended_addr, daddr,
  75                sizeof(info->daddr.u.extended_addr));
  76         info->saddr.mode = IEEE802154_ADDR_LONG;
  77         memcpy(&info->saddr.u.extended_addr, saddr,
  78                sizeof(info->daddr.u.extended_addr));
  79
  80         return 0;
  81 }
  82
  83 static struct sk_buff*
  84 lowpan_alloc_frag(struct sk_buff *skb, int size,
  85                   const struct ieee802154_hdr *master_hdr, bool frag1)
  86 {
  87         struct net_device *wdev = lowpan_dev_info(skb->dev)->wdev;
  88         struct sk_buff *frag;
  89         int rc;
  90
  91         frag = alloc_skb(wdev->needed_headroom + wdev->needed_tailroom + size,
  92                          GFP_ATOMIC);
  93
  94         if (likely(frag)) {
  95                 frag->dev = wdev;
  96                 frag->priority = skb->priority;
  97                 skb_reserve(frag, wdev->needed_headroom);
  98                 skb_reset_network_header(frag);
  99                 *mac_cb(frag) = *mac_cb(skb);
 100
 101                 if (frag1) {
 102                         memcpy(skb_put(frag, skb->mac_len),
 103                                skb_mac_header(skb), skb->mac_len);
 104                 } else {
 105                         rc = wpan_dev_hard_header(frag, wdev,
 106                                                   &master_hdr->dest,
 107                                                   &master_hdr->source, size);
 108                         if (rc < 0) {
 109                                 kfree_skb(frag);
 110                                 return ERR_PTR(rc);
 111                         }
 112                 }
 113         } else {
 114                 frag = ERR_PTR(-ENOMEM);
 115         }
 116
 117         return frag;
 118 }
 119
 120 static int
 121 lowpan_xmit_fragment(struct sk_buff *skb, const struct ieee802154_hdr *wpan_hdr,
 122                      u8 *frag_hdr, int frag_hdrlen,
 123                      int offset, int len, bool frag1)
 124 {
 125         struct sk_buff *frag;
 126
 127         raw_dump_inline(__func__, " fragment header", frag_hdr, frag_hdrlen);
 128
 129         frag = lowpan_alloc_frag(skb, frag_hdrlen + len, wpan_hdr, frag1);
 130         if (IS_ERR(frag))
 131                 return PTR_ERR(frag);
 132
 133         memcpy(skb_put(frag, frag_hdrlen), frag_hdr, frag_hdrlen);
 134         memcpy(skb_put(frag, len), skb_network_header(skb) + offset, len);
 135
 136         raw_dump_table(__func__, " fragment dump", frag->data, frag->len);
 137
 138         return dev_queue_xmit(frag);
 139 }
 140
 141 static int
 142 lowpan_xmit_fragmented(struct sk_buff *skb, struct net_device *ldev,
 143                        const struct ieee802154_hdr *wpan_hdr, u16 dgram_size,
 144                        u16 dgram_offset)
 145 {
 146         __be16 frag_tag;
 147         u8 frag_hdr[5];
 148         int frag_cap, frag_len, payload_cap, rc;
 149         int skb_unprocessed, skb_offset;
 150
 151         frag_tag = htons(lowpan_dev_info(ldev)->fragment_tag);
 152         lowpan_dev_info(ldev)->fragment_tag++;
 153
 154         frag_hdr[0] = LOWPAN_DISPATCH_FRAG1 | ((dgram_size >> 8) & 0x07);
 155         frag_hdr[1] = dgram_size & 0xff;
 156         memcpy(frag_hdr + 2, &frag_tag, sizeof(frag_tag));
 157
 158         payload_cap = ieee802154_max_payload(wpan_hdr);
 159
 160         frag_len = round_down(payload_cap - LOWPAN_FRAG1_HEAD_SIZE -
 161                               skb_network_header_len(skb), 8);
 162
 163         skb_offset = skb_network_header_len(skb);
 164         skb_unprocessed = skb->len - skb->mac_len - skb_offset;
 165
 166         rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
 167                                   LOWPAN_FRAG1_HEAD_SIZE, 0,
 168                                   frag_len + skb_network_header_len(skb),
 169                                   true);
 170         if (rc) {
 171                 pr_debug("%s unable to send FRAG1 packet (tag: %d)",
 172                          __func__, ntohs(frag_tag));
 173                 goto err;
 174         }
 175
 176         frag_hdr[0] &= ~LOWPAN_DISPATCH_FRAG1;
 177         frag_hdr[0] |= LOWPAN_DISPATCH_FRAGN;
 178         frag_cap = round_down(payload_cap - LOWPAN_FRAGN_HEAD_SIZE, 8);
 179
 180         do {
 181                 dgram_offset += frag_len;
 182                 skb_offset += frag_len;
 183                 skb_unprocessed -= frag_len;
 184                 frag_len = min(frag_cap, skb_unprocessed);
 185
 186                 frag_hdr[4] = dgram_offset >> 3;
 187
 188                 rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
 189                                           LOWPAN_FRAGN_HEAD_SIZE, skb_offset,
 190                                           frag_len, false);
 191                 if (rc) {
 192                         pr_debug("%s unable to send a FRAGN packet. (tag: %d, offset: %d)\n",
 193                                  __func__, ntohs(frag_tag), skb_offset);
 194                         goto err;
 195                 }
 196         } while (skb_unprocessed > frag_cap);
 197
 198         ldev->stats.tx_packets++;
 199         ldev->stats.tx_bytes += dgram_size;
 200         consume_skb(skb);
 201         return NET_XMIT_SUCCESS;
 202
 203 err:
 204         kfree_skb(skb);
 205         return rc;
 206 }
 207
 208 static int lowpan_header(struct sk_buff *skb, struct net_device *ldev,
 209                          u16 *dgram_size, u16 *dgram_offset)
 210 {
 211         struct wpan_dev *wpan_dev = lowpan_dev_info(ldev)->wdev->ieee802154_ptr;
 212         struct ieee802154_addr sa, da;
 213         struct ieee802154_mac_cb *cb = mac_cb_init(skb);
 214         struct lowpan_addr_info info;
 215         void *daddr, *saddr;
 216
 217         memcpy(&info, lowpan_skb_priv(skb), sizeof(info));
 218
 219         /* TODO: Currently we only support extended_addr */
 220         daddr = &info.daddr.u.extended_addr;
 221         saddr = &info.saddr.u.extended_addr;
 222
 223         *dgram_size = skb->len;
 224         lowpan_header_compress(skb, ldev, daddr, saddr);
 225         /* dgram_offset = (saved bytes after compression) + lowpan header len */
 226         *dgram_offset = (*dgram_size - skb->len) + skb_network_header_len(skb);
 227
 228         cb->type = IEEE802154_FC_TYPE_DATA;
 229
 230         /* prepare wpan address data */
 231         sa.mode = IEEE802154_ADDR_LONG;
 232         sa.pan_id = wpan_dev->pan_id;
 233         sa.extended_addr = ieee802154_devaddr_from_raw(saddr);
 234
 235         /* intra-PAN communications */
 236         da.pan_id = sa.pan_id;
 237
 238         /* if the destination address is the broadcast address, use the
 239          * corresponding short address
 240          */
 241         if (!memcmp(daddr, ldev->broadcast, EUI64_ADDR_LEN)) {
 242                 da.mode = IEEE802154_ADDR_SHORT;
 243                 da.short_addr = cpu_to_le16(IEEE802154_ADDR_BROADCAST);
 244                 cb->ackreq = false;
 245         } else {
 246                 da.mode = IEEE802154_ADDR_LONG;
 247                 da.extended_addr = ieee802154_devaddr_from_raw(daddr);
 248                 cb->ackreq = wpan_dev->ackreq;
 249         }
 250
 251         return wpan_dev_hard_header(skb, lowpan_dev_info(ldev)->wdev, &da, &sa,
 252                                     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_dev_info(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 }