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         if (!daddr)
  59                 return -EINVAL;
  60
  61         /* TODO:
  62          * if this package isn't ipv6 one, where should it be routed?
  63          */
  64         if (type != ETH_P_IPV6)
  65                 return 0;
  66
  67         if (!saddr)
  68                 saddr = ldev->dev_addr;
  69
  70         raw_dump_inline(__func__, "saddr", (unsigned char *)saddr, 8);
  71         raw_dump_inline(__func__, "daddr", (unsigned char *)daddr, 8);
  72
  73         info = lowpan_skb_priv(skb);
  74
  75         /* TODO: Currently we only support extended_addr */
  76         info->daddr.mode = IEEE802154_ADDR_LONG;
  77         memcpy(&info->daddr.u.extended_addr, daddr,
  78                sizeof(info->daddr.u.extended_addr));
  79         info->saddr.mode = IEEE802154_ADDR_LONG;
  80         memcpy(&info->saddr.u.extended_addr, saddr,
  81                sizeof(info->daddr.u.extended_addr));
  82
  83         return 0;
  84 }
  85
  86 static struct sk_buff*
  87 lowpan_alloc_frag(struct sk_buff *skb, int size,
  88                   const struct ieee802154_hdr *master_hdr, bool frag1)
  89 {
  90         struct net_device *wdev = lowpan_dev_info(skb->dev)->wdev;
  91         struct sk_buff *frag;
  92         int rc;
  93
  94         frag = alloc_skb(wdev->needed_headroom + wdev->needed_tailroom + size,
  95                          GFP_ATOMIC);
  96
  97         if (likely(frag)) {
  98                 frag->dev = wdev;
  99                 frag->priority = skb->priority;
 100                 skb_reserve(frag, wdev->needed_headroom);
 101                 skb_reset_network_header(frag);
 102                 *mac_cb(frag) = *mac_cb(skb);
 103
 104                 if (frag1) {
 105                         memcpy(skb_put(frag, skb->mac_len),
 106                                skb_mac_header(skb), skb->mac_len);
 107                 } else {
 108                         rc = wpan_dev_hard_header(frag, wdev,
 109                                                   &master_hdr->dest,
 110                                                   &master_hdr->source, size);
 111                         if (rc < 0) {
 112                                 kfree_skb(frag);
 113                                 return ERR_PTR(rc);
 114                         }
 115                 }
 116         } else {
 117                 frag = ERR_PTR(-ENOMEM);
 118         }
 119
 120         return frag;
 121 }
 122
 123 static int
 124 lowpan_xmit_fragment(struct sk_buff *skb, const struct ieee802154_hdr *wpan_hdr,
 125                      u8 *frag_hdr, int frag_hdrlen,
 126                      int offset, int len, bool frag1)
 127 {
 128         struct sk_buff *frag;
 129
 130         raw_dump_inline(__func__, " fragment header", frag_hdr, frag_hdrlen);
 131
 132         frag = lowpan_alloc_frag(skb, frag_hdrlen + len, wpan_hdr, frag1);
 133         if (IS_ERR(frag))
 134                 return PTR_ERR(frag);
 135
 136         memcpy(skb_put(frag, frag_hdrlen), frag_hdr, frag_hdrlen);
 137         memcpy(skb_put(frag, len), skb_network_header(skb) + offset, len);
 138
 139         raw_dump_table(__func__, " fragment dump", frag->data, frag->len);
 140
 141         return dev_queue_xmit(frag);
 142 }
 143
 144 static int
 145 lowpan_xmit_fragmented(struct sk_buff *skb, struct net_device *ldev,
 146                        const struct ieee802154_hdr *wpan_hdr, u16 dgram_size,
 147                        u16 dgram_offset)
 148 {
 149         __be16 frag_tag;
 150         u8 frag_hdr[5];
 151         int frag_cap, frag_len, payload_cap, rc;
 152         int skb_unprocessed, skb_offset;
 153
 154         frag_tag = htons(lowpan_dev_info(ldev)->fragment_tag);
 155         lowpan_dev_info(ldev)->fragment_tag++;
 156
 157         frag_hdr[0] = LOWPAN_DISPATCH_FRAG1 | ((dgram_size >> 8) & 0x07);
 158         frag_hdr[1] = dgram_size & 0xff;
 159         memcpy(frag_hdr + 2, &frag_tag, sizeof(frag_tag));
 160
 161         payload_cap = ieee802154_max_payload(wpan_hdr);
 162
 163         frag_len = round_down(payload_cap - LOWPAN_FRAG1_HEAD_SIZE -
 164                               skb_network_header_len(skb), 8);
 165
 166         skb_offset = skb_network_header_len(skb);
 167         skb_unprocessed = skb->len - skb->mac_len - skb_offset;
 168
 169         rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
 170                                   LOWPAN_FRAG1_HEAD_SIZE, 0,
 171                                   frag_len + skb_network_header_len(skb),
 172                                   true);
 173         if (rc) {
 174                 pr_debug("%s unable to send FRAG1 packet (tag: %d)",
 175                          __func__, ntohs(frag_tag));
 176                 goto err;
 177         }
 178
 179         frag_hdr[0] &= ~LOWPAN_DISPATCH_FRAG1;
 180         frag_hdr[0] |= LOWPAN_DISPATCH_FRAGN;
 181         frag_cap = round_down(payload_cap - LOWPAN_FRAGN_HEAD_SIZE, 8);
 182
 183         do {
 184                 dgram_offset += frag_len;
 185                 skb_offset += frag_len;
 186                 skb_unprocessed -= frag_len;
 187                 frag_len = min(frag_cap, skb_unprocessed);
 188
 189                 frag_hdr[4] = dgram_offset >> 3;
 190
 191                 rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
 192                                           LOWPAN_FRAGN_HEAD_SIZE, skb_offset,
 193                                           frag_len, false);
 194                 if (rc) {
 195                         pr_debug("%s unable to send a FRAGN packet. (tag: %d, offset: %d)\n",
 196                                  __func__, ntohs(frag_tag), skb_offset);
 197                         goto err;
 198                 }
 199         } while (skb_unprocessed > frag_cap);
 200
 201         ldev->stats.tx_packets++;
 202         ldev->stats.tx_bytes += dgram_size;
 203         consume_skb(skb);
 204         return NET_XMIT_SUCCESS;
 205
 206 err:
 207         kfree_skb(skb);
 208         return rc;
 209 }
 210
 211 static int lowpan_header(struct sk_buff *skb, struct net_device *ldev,
 212                          u16 *dgram_size, u16 *dgram_offset)
 213 {
 214         struct wpan_dev *wpan_dev = lowpan_dev_info(ldev)->wdev->ieee802154_ptr;
 215         struct ieee802154_addr sa, da;
 216         struct ieee802154_mac_cb *cb = mac_cb_init(skb);
 217         struct lowpan_addr_info info;
 218         void *daddr, *saddr;
 219
 220         memcpy(&info, lowpan_skb_priv(skb), sizeof(info));
 221
 222         /* TODO: Currently we only support extended_addr */
 223         daddr = &info.daddr.u.extended_addr;
 224         saddr = &info.saddr.u.extended_addr;
 225
 226         *dgram_size = skb->len;
 227         lowpan_header_compress(skb, ldev, daddr, saddr);
 228         /* dgram_offset = (saved bytes after compression) + lowpan header len */
 229         *dgram_offset = (*dgram_size - skb->len) + skb_network_header_len(skb);
 230
 231         cb->type = IEEE802154_FC_TYPE_DATA;
 232
 233         /* prepare wpan address data */
 234         sa.mode = IEEE802154_ADDR_LONG;
 235         sa.pan_id = wpan_dev->pan_id;
 236         sa.extended_addr = ieee802154_devaddr_from_raw(saddr);
 237
 238         /* intra-PAN communications */
 239         da.pan_id = sa.pan_id;
 240
 241         /* if the destination address is the broadcast address, use the
 242          * corresponding short address
 243          */
 244         if (!memcmp(daddr, ldev->broadcast, EUI64_ADDR_LEN)) {
 245                 da.mode = IEEE802154_ADDR_SHORT;
 246                 da.short_addr = cpu_to_le16(IEEE802154_ADDR_BROADCAST);
 247                 cb->ackreq = false;
 248         } else {
 249                 da.mode = IEEE802154_ADDR_LONG;
 250                 da.extended_addr = ieee802154_devaddr_from_raw(daddr);
 251                 cb->ackreq = wpan_dev->ackreq;
 252         }
 253
 254         return wpan_dev_hard_header(skb, lowpan_dev_info(ldev)->wdev, &da, &sa,
 255                                     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_dev_info(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 }