net/ieee802154/6lowpan/tx.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2
   3 #include <net/6lowpan.h>
   4 #include <net/ndisc.h>
   5 #include <net/ieee802154_netdev.h>
   6 #include <net/mac802154.h>
   7
   8 #include "6lowpan_i.h"
   9
  10 #define LOWPAN_FRAG1_HEAD_SIZE  0x4
  11 #define LOWPAN_FRAGN_HEAD_SIZE  0x5
  12
  13 struct lowpan_addr_info {
  14         struct ieee802154_addr daddr;
  15         struct ieee802154_addr saddr;
  16 };
  17
  18 static inline struct
  19 lowpan_addr_info *lowpan_skb_priv(const struct sk_buff *skb)
  20 {
  21         WARN_ON_ONCE(skb_headroom(skb) < sizeof(struct lowpan_addr_info));
  22         return (struct lowpan_addr_info *)(skb->data -
  23                         sizeof(struct lowpan_addr_info));
  24 }
  25
  26 /* This callback will be called from AF_PACKET and IPv6 stack, the AF_PACKET
  27  * sockets gives an 8 byte array for addresses only!
  28  *
  29  * TODO I think AF_PACKET DGRAM (sending/receiving) RAW (sending) makes no
  30  * sense here. We should disable it, the right use-case would be AF_INET6
  31  * RAW/DGRAM sockets.
  32  */
  33 int lowpan_header_create(struct sk_buff *skb, struct net_device *ldev,
  34                          unsigned short type, const void *daddr,
  35                          const void *saddr, unsigned int len)
  36 {
  37         struct wpan_dev *wpan_dev = lowpan_802154_dev(ldev)->wdev->ieee802154_ptr;
  38         struct lowpan_addr_info *info = lowpan_skb_priv(skb);
  39         struct lowpan_802154_neigh *llneigh = NULL;
  40         const struct ipv6hdr *hdr = ipv6_hdr(skb);
  41         struct neighbour *n;
  42
  43         if (!daddr)
  44                 return -EINVAL;
  45
  46         /* TODO:
  47          * if this package isn't ipv6 one, where should it be routed?
  48          */
  49         if (type != ETH_P_IPV6)
  50                 return 0;
  51
  52         /* intra-pan communication */
  53         info->saddr.pan_id = wpan_dev->pan_id;
  54         info->daddr.pan_id = info->saddr.pan_id;
  55
  56         if (!memcmp(daddr, ldev->broadcast, EUI64_ADDR_LEN)) {
  57                 info->daddr.short_addr = cpu_to_le16(IEEE802154_ADDR_BROADCAST);
  58                 info->daddr.mode = IEEE802154_ADDR_SHORT;
  59         } else {
  60                 __le16 short_addr = cpu_to_le16(IEEE802154_ADDR_SHORT_UNSPEC);
  61
  62                 n = neigh_lookup(&nd_tbl, &hdr->daddr, ldev);
  63                 if (n) {
  64                         llneigh = lowpan_802154_neigh(neighbour_priv(n));
  65                         read_lock_bh(&n->lock);
  66                         short_addr = llneigh->short_addr;
  67                         read_unlock_bh(&n->lock);
  68                 }
  69
  70                 if (llneigh &&
  71                     lowpan_802154_is_valid_src_short_addr(short_addr)) {
  72                         info->daddr.short_addr = short_addr;
  73                         info->daddr.mode = IEEE802154_ADDR_SHORT;
  74                 } else {
  75                         info->daddr.mode = IEEE802154_ADDR_LONG;
  76                         ieee802154_be64_to_le64(&info->daddr.extended_addr,
  77                                                 daddr);
  78                 }
  79
  80                 if (n)
  81                         neigh_release(n);
  82         }
  83
  84         if (!saddr) {
  85                 if (lowpan_802154_is_valid_src_short_addr(wpan_dev->short_addr)) {
  86                         info->saddr.mode = IEEE802154_ADDR_SHORT;
  87                         info->saddr.short_addr = wpan_dev->short_addr;
  88                 } else {
  89                         info->saddr.mode = IEEE802154_ADDR_LONG;
  90                         info->saddr.extended_addr = wpan_dev->extended_addr;
  91                 }
  92         } else {
  93                 info->saddr.mode = IEEE802154_ADDR_LONG;
  94                 ieee802154_be64_to_le64(&info->saddr.extended_addr, saddr);
  95         }
  96
  97         return 0;
  98 }
  99
 100 static struct sk_buff*
 101 lowpan_alloc_frag(struct sk_buff *skb, int size,
 102                   const struct ieee802154_hdr *master_hdr, bool frag1)
 103 {
 104         struct net_device *wdev = lowpan_802154_dev(skb->dev)->wdev;
 105         struct sk_buff *frag;
 106         int rc;
 107
 108         frag = alloc_skb(wdev->needed_headroom + wdev->needed_tailroom + size,
 109                          GFP_ATOMIC);
 110
 111         if (likely(frag)) {
 112                 frag->dev = wdev;
 113                 frag->priority = skb->priority;
 114                 skb_reserve(frag, wdev->needed_headroom);
 115                 skb_reset_network_header(frag);
 116                 *mac_cb(frag) = *mac_cb(skb);
 117
 118                 if (frag1) {
 119                         skb_put_data(frag, skb_mac_header(skb), skb->mac_len);
 120                 } else {
 121                         rc = wpan_dev_hard_header(frag, wdev,
 122                                                   &master_hdr->dest,
 123                                                   &master_hdr->source, size);
 124                         if (rc < 0) {
 125                                 kfree_skb(frag);
 126                                 return ERR_PTR(rc);
 127                         }
 128                 }
 129         } else {
 130                 frag = ERR_PTR(-ENOMEM);
 131         }
 132
 133         return frag;
 134 }
 135
 136 static int
 137 lowpan_xmit_fragment(struct sk_buff *skb, const struct ieee802154_hdr *wpan_hdr,
 138                      u8 *frag_hdr, int frag_hdrlen,
 139                      int offset, int len, bool frag1)
 140 {
 141         struct sk_buff *frag;
 142
 143         raw_dump_inline(__func__, " fragment header", frag_hdr, frag_hdrlen);
 144
 145         frag = lowpan_alloc_frag(skb, frag_hdrlen + len, wpan_hdr, frag1);
 146         if (IS_ERR(frag))
 147                 return PTR_ERR(frag);
 148
 149         skb_put_data(frag, frag_hdr, frag_hdrlen);
 150         skb_put_data(frag, skb_network_header(skb) + offset, len);
 151
 152         raw_dump_table(__func__, " fragment dump", frag->data, frag->len);
 153
 154         return dev_queue_xmit(frag);
 155 }
 156
 157 static int
 158 lowpan_xmit_fragmented(struct sk_buff *skb, struct net_device *ldev,
 159                        const struct ieee802154_hdr *wpan_hdr, u16 dgram_size,
 160                        u16 dgram_offset)
 161 {
 162         __be16 frag_tag;
 163         u8 frag_hdr[5];
 164         int frag_cap, frag_len, payload_cap, rc;
 165         int skb_unprocessed, skb_offset;
 166
 167         frag_tag = htons(lowpan_802154_dev(ldev)->fragment_tag);
 168         lowpan_802154_dev(ldev)->fragment_tag++;
 169
 170         frag_hdr[0] = LOWPAN_DISPATCH_FRAG1 | ((dgram_size >> 8) & 0x07);
 171         frag_hdr[1] = dgram_size & 0xff;
 172         memcpy(frag_hdr + 2, &frag_tag, sizeof(frag_tag));
 173
 174         payload_cap = ieee802154_max_payload(wpan_hdr);
 175
 176         frag_len = round_down(payload_cap - LOWPAN_FRAG1_HEAD_SIZE -
 177                               skb_network_header_len(skb), 8);
 178
 179         skb_offset = skb_network_header_len(skb);
 180         skb_unprocessed = skb->len - skb->mac_len - skb_offset;
 181
 182         rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
 183                                   LOWPAN_FRAG1_HEAD_SIZE, 0,
 184                                   frag_len + skb_network_header_len(skb),
 185                                   true);
 186         if (rc) {
 187                 pr_debug("%s unable to send FRAG1 packet (tag: %d)",
 188                          __func__, ntohs(frag_tag));
 189                 goto err;
 190         }
 191
 192         frag_hdr[0] &= ~LOWPAN_DISPATCH_FRAG1;
 193         frag_hdr[0] |= LOWPAN_DISPATCH_FRAGN;
 194         frag_cap = round_down(payload_cap - LOWPAN_FRAGN_HEAD_SIZE, 8);
 195
 196         do {
 197                 dgram_offset += frag_len;
 198                 skb_offset += frag_len;
 199                 skb_unprocessed -= frag_len;
 200                 frag_len = min(frag_cap, skb_unprocessed);
 201
 202                 frag_hdr[4] = dgram_offset >> 3;
 203
 204                 rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
 205                                           LOWPAN_FRAGN_HEAD_SIZE, skb_offset,
 206                                           frag_len, false);
 207                 if (rc) {
 208                         pr_debug("%s unable to send a FRAGN packet. (tag: %d, offset: %d)\n",
 209                                  __func__, ntohs(frag_tag), skb_offset);
 210                         goto err;
 211                 }
 212         } while (skb_unprocessed > frag_cap);
 213
 214         ldev->stats.tx_packets++;
 215         ldev->stats.tx_bytes += dgram_size;
 216         consume_skb(skb);
 217         return NET_XMIT_SUCCESS;
 218
 219 err:
 220         kfree_skb(skb);
 221         return rc;
 222 }
 223
 224 static int lowpan_header(struct sk_buff *skb, struct net_device *ldev,
 225                          u16 *dgram_size, u16 *dgram_offset)
 226 {
 227         struct wpan_dev *wpan_dev = lowpan_802154_dev(ldev)->wdev->ieee802154_ptr;
 228         struct ieee802154_mac_cb *cb = mac_cb_init(skb);
 229         struct lowpan_addr_info info;
 230
 231         memcpy(&info, lowpan_skb_priv(skb), sizeof(info));
 232
 233         *dgram_size = skb->len;
 234         lowpan_header_compress(skb, ldev, &info.daddr, &info.saddr);
 235         /* dgram_offset = (saved bytes after compression) + lowpan header len */
 236         *dgram_offset = (*dgram_size - skb->len) + skb_network_header_len(skb);
 237
 238         cb->type = IEEE802154_FC_TYPE_DATA;
 239
 240         if (info.daddr.mode == IEEE802154_ADDR_SHORT &&
 241             ieee802154_is_broadcast_short_addr(info.daddr.short_addr))
 242                 cb->ackreq = false;
 243         else
 244                 cb->ackreq = wpan_dev->ackreq;
 245
 246         return wpan_dev_hard_header(skb, lowpan_802154_dev(ldev)->wdev,
 247                                     &info.daddr, &info.saddr, 0);
 248 }
 249
 250 netdev_tx_t lowpan_xmit(struct sk_buff *skb, struct net_device *ldev)
 251 {
 252         struct ieee802154_hdr wpan_hdr;
 253         int max_single, ret;
 254         u16 dgram_size, dgram_offset;
 255
 256         pr_debug("package xmit\n");
 257
 258         WARN_ON_ONCE(skb->len > IPV6_MIN_MTU);
 259
 260         /* We must take a copy of the skb before we modify/replace the ipv6
 261          * header as the header could be used elsewhere
 262          */
 263         if (unlikely(skb_headroom(skb) < ldev->needed_headroom ||
 264                      skb_tailroom(skb) < ldev->needed_tailroom)) {
 265                 struct sk_buff *nskb;
 266
 267                 nskb = skb_copy_expand(skb, ldev->needed_headroom,
 268                                        ldev->needed_tailroom, GFP_ATOMIC);
 269                 if (likely(nskb)) {
 270                         consume_skb(skb);
 271                         skb = nskb;
 272                 } else {
 273                         kfree_skb(skb);
 274                         return NET_XMIT_DROP;
 275                 }
 276         } else {
 277                 skb = skb_unshare(skb, GFP_ATOMIC);
 278                 if (!skb)
 279                         return NET_XMIT_DROP;
 280         }
 281
 282         ret = lowpan_header(skb, ldev, &dgram_size, &dgram_offset);
 283         if (ret < 0) {
 284                 kfree_skb(skb);
 285                 return NET_XMIT_DROP;
 286         }
 287
 288         if (ieee802154_hdr_peek(skb, &wpan_hdr) < 0) {
 289                 kfree_skb(skb);
 290                 return NET_XMIT_DROP;
 291         }
 292
 293         max_single = ieee802154_max_payload(&wpan_hdr);
 294
 295         if (skb_tail_pointer(skb) - skb_network_header(skb) <= max_single) {
 296                 skb->dev = lowpan_802154_dev(ldev)->wdev;
 297                 ldev->stats.tx_packets++;
 298                 ldev->stats.tx_bytes += dgram_size;
 299                 return dev_queue_xmit(skb);
 300         } else {
 301                 netdev_tx_t rc;
 302
 303                 pr_debug("frame is too big, fragmentation is needed\n");
 304                 rc = lowpan_xmit_fragmented(skb, ldev, &wpan_hdr, dgram_size,
 305                                             dgram_offset);
 306
 307                 return rc < 0 ? NET_XMIT_DROP : rc;
 308         }
 309 }