net/ieee802154/6lowpan/rx.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 <linux/if_arp.h>
  12
  13 #include <net/6lowpan.h>
  14 #include <net/mac802154.h>
  15 #include <net/ieee802154_netdev.h>
  16
  17 #include "6lowpan_i.h"
  18
  19 #define LOWPAN_DISPATCH_FIRST           0xc0
  20 #define LOWPAN_DISPATCH_FRAG_MASK       0xf8
  21
  22 #define LOWPAN_DISPATCH_NALP            0x00
  23 #define LOWPAN_DISPATCH_ESC             0x40
  24 #define LOWPAN_DISPATCH_HC1             0x42
  25 #define LOWPAN_DISPATCH_DFF             0x43
  26 #define LOWPAN_DISPATCH_BC0             0x50
  27 #define LOWPAN_DISPATCH_MESH            0x80
  28
  29 static int lowpan_give_skb_to_device(struct sk_buff *skb)
  30 {
  31         skb->protocol = htons(ETH_P_IPV6);
  32         skb->dev->stats.rx_packets++;
  33         skb->dev->stats.rx_bytes += skb->len;
  34
  35         return netif_rx(skb);
  36 }
  37
  38 static int lowpan_rx_handlers_result(struct sk_buff *skb, lowpan_rx_result res)
  39 {
  40         switch (res) {
  41         case RX_CONTINUE:
  42                 /* nobody cared about this packet */
  43                 net_warn_ratelimited("%s: received unknown dispatch\n",
  44                                      __func__);
  45
  46                 /* fall-through */
  47         case RX_DROP_UNUSABLE:
  48                 kfree_skb(skb);
  49
  50                 /* fall-through */
  51         case RX_DROP:
  52                 return NET_RX_DROP;
  53         case RX_QUEUED:
  54                 return lowpan_give_skb_to_device(skb);
  55         default:
  56                 break;
  57         }
  58
  59         return NET_RX_DROP;
  60 }
  61
  62 static inline bool lowpan_is_frag1(u8 dispatch)
  63 {
  64         return (dispatch & LOWPAN_DISPATCH_FRAG_MASK) == LOWPAN_DISPATCH_FRAG1;
  65 }
  66
  67 static inline bool lowpan_is_fragn(u8 dispatch)
  68 {
  69         return (dispatch & LOWPAN_DISPATCH_FRAG_MASK) == LOWPAN_DISPATCH_FRAGN;
  70 }
  71
  72 static lowpan_rx_result lowpan_rx_h_frag(struct sk_buff *skb)
  73 {
  74         int ret;
  75
  76         if (!(lowpan_is_frag1(*skb_network_header(skb)) ||
  77               lowpan_is_fragn(*skb_network_header(skb))))
  78                 return RX_CONTINUE;
  79
  80         ret = lowpan_frag_rcv(skb, *skb_network_header(skb) &
  81                               LOWPAN_DISPATCH_FRAG_MASK);
  82         if (ret == 1)
  83                 return RX_QUEUED;
  84
  85         /* Packet is freed by lowpan_frag_rcv on error or put into the frag
  86          * bucket.
  87          */
  88         return RX_DROP;
  89 }
  90
  91 int lowpan_iphc_decompress(struct sk_buff *skb)
  92 {
  93         struct ieee802154_hdr hdr;
  94
  95         if (ieee802154_hdr_peek_addrs(skb, &hdr) < 0)
  96                 return -EINVAL;
  97
  98         return lowpan_header_decompress(skb, skb->dev, &hdr.dest, &hdr.source);
  99 }
 100
 101 static lowpan_rx_result lowpan_rx_h_iphc(struct sk_buff *skb)
 102 {
 103         int ret;
 104
 105         if (!lowpan_is_iphc(*skb_network_header(skb)))
 106                 return RX_CONTINUE;
 107
 108         /* Setting datagram_offset to zero indicates non frag handling
 109          * while doing lowpan_header_decompress.
 110          */
 111         lowpan_802154_cb(skb)->d_size = 0;
 112
 113         ret = lowpan_iphc_decompress(skb);
 114         if (ret < 0)
 115                 return RX_DROP_UNUSABLE;
 116
 117         return RX_QUEUED;
 118 }
 119
 120 lowpan_rx_result lowpan_rx_h_ipv6(struct sk_buff *skb)
 121 {
 122         if (!lowpan_is_ipv6(*skb_network_header(skb)))
 123                 return RX_CONTINUE;
 124
 125         /* Pull off the 1-byte of 6lowpan header. */
 126         skb_pull(skb, 1);
 127         return RX_QUEUED;
 128 }
 129
 130 static inline bool lowpan_is_esc(u8 dispatch)
 131 {
 132         return dispatch == LOWPAN_DISPATCH_ESC;
 133 }
 134
 135 static lowpan_rx_result lowpan_rx_h_esc(struct sk_buff *skb)
 136 {
 137         if (!lowpan_is_esc(*skb_network_header(skb)))
 138                 return RX_CONTINUE;
 139
 140         net_warn_ratelimited("%s: %s\n", skb->dev->name,
 141                              "6LoWPAN ESC not supported\n");
 142
 143         return RX_DROP_UNUSABLE;
 144 }
 145
 146 static inline bool lowpan_is_hc1(u8 dispatch)
 147 {
 148         return dispatch == LOWPAN_DISPATCH_HC1;
 149 }
 150
 151 static lowpan_rx_result lowpan_rx_h_hc1(struct sk_buff *skb)
 152 {
 153         if (!lowpan_is_hc1(*skb_network_header(skb)))
 154                 return RX_CONTINUE;
 155
 156         net_warn_ratelimited("%s: %s\n", skb->dev->name,
 157                              "6LoWPAN HC1 not supported\n");
 158
 159         return RX_DROP_UNUSABLE;
 160 }
 161
 162 static inline bool lowpan_is_dff(u8 dispatch)
 163 {
 164         return dispatch == LOWPAN_DISPATCH_DFF;
 165 }
 166
 167 static lowpan_rx_result lowpan_rx_h_dff(struct sk_buff *skb)
 168 {
 169         if (!lowpan_is_dff(*skb_network_header(skb)))
 170                 return RX_CONTINUE;
 171
 172         net_warn_ratelimited("%s: %s\n", skb->dev->name,
 173                              "6LoWPAN DFF not supported\n");
 174
 175         return RX_DROP_UNUSABLE;
 176 }
 177
 178 static inline bool lowpan_is_bc0(u8 dispatch)
 179 {
 180         return dispatch == LOWPAN_DISPATCH_BC0;
 181 }
 182
 183 static lowpan_rx_result lowpan_rx_h_bc0(struct sk_buff *skb)
 184 {
 185         if (!lowpan_is_bc0(*skb_network_header(skb)))
 186                 return RX_CONTINUE;
 187
 188         net_warn_ratelimited("%s: %s\n", skb->dev->name,
 189                              "6LoWPAN BC0 not supported\n");
 190
 191         return RX_DROP_UNUSABLE;
 192 }
 193
 194 static inline bool lowpan_is_mesh(u8 dispatch)
 195 {
 196         return (dispatch & LOWPAN_DISPATCH_FIRST) == LOWPAN_DISPATCH_MESH;
 197 }
 198
 199 static lowpan_rx_result lowpan_rx_h_mesh(struct sk_buff *skb)
 200 {
 201         if (!lowpan_is_mesh(*skb_network_header(skb)))
 202                 return RX_CONTINUE;
 203
 204         net_warn_ratelimited("%s: %s\n", skb->dev->name,
 205                              "6LoWPAN MESH not supported\n");
 206
 207         return RX_DROP_UNUSABLE;
 208 }
 209
 210 static int lowpan_invoke_rx_handlers(struct sk_buff *skb)
 211 {
 212         lowpan_rx_result res;
 213
 214 #define CALL_RXH(rxh)                   \
 215         do {                            \
 216                 res = rxh(skb); \
 217                 if (res != RX_CONTINUE) \
 218                         goto rxh_next;  \
 219         } while (0)
 220
 221         /* likely at first */
 222         CALL_RXH(lowpan_rx_h_iphc);
 223         CALL_RXH(lowpan_rx_h_frag);
 224         CALL_RXH(lowpan_rx_h_ipv6);
 225         CALL_RXH(lowpan_rx_h_esc);
 226         CALL_RXH(lowpan_rx_h_hc1);
 227         CALL_RXH(lowpan_rx_h_dff);
 228         CALL_RXH(lowpan_rx_h_bc0);
 229         CALL_RXH(lowpan_rx_h_mesh);
 230
 231 rxh_next:
 232         return lowpan_rx_handlers_result(skb, res);
 233 #undef CALL_RXH
 234 }
 235
 236 static inline bool lowpan_is_nalp(u8 dispatch)
 237 {
 238         return (dispatch & LOWPAN_DISPATCH_FIRST) == LOWPAN_DISPATCH_NALP;
 239 }
 240
 241 /* Lookup for reserved dispatch values at:
 242  * https://www.iana.org/assignments/_6lowpan-parameters/_6lowpan-parameters.xhtml#_6lowpan-parameters-1
 243  *
 244  * Last Updated: 2015-01-22
 245  */
 246 static inline bool lowpan_is_reserved(u8 dispatch)
 247 {
 248         return ((dispatch >= 0x44 && dispatch <= 0x4F) ||
 249                 (dispatch >= 0x51 && dispatch <= 0x5F) ||
 250                 (dispatch >= 0xc8 && dispatch <= 0xdf) ||
 251                 (dispatch >= 0xe8 && dispatch <= 0xff));
 252 }
 253
 254 /* lowpan_rx_h_check checks on generic 6LoWPAN requirements
 255  * in MAC and 6LoWPAN header.
 256  *
 257  * Don't manipulate the skb here, it could be shared buffer.
 258  */
 259 static inline bool lowpan_rx_h_check(struct sk_buff *skb)
 260 {
 261         __le16 fc = ieee802154_get_fc_from_skb(skb);
 262
 263         /* check on ieee802154 conform 6LoWPAN header */
 264         if (!ieee802154_is_data(fc) ||
 265             !ieee802154_is_intra_pan(fc))
 266                 return false;
 267
 268         /* check if we can dereference the dispatch */
 269         if (unlikely(!skb->len))
 270                 return false;
 271
 272         if (lowpan_is_nalp(*skb_network_header(skb)) ||
 273             lowpan_is_reserved(*skb_network_header(skb)))
 274                 return false;
 275
 276         return true;
 277 }
 278
 279 static int lowpan_rcv(struct sk_buff *skb, struct net_device *wdev,
 280                       struct packet_type *pt, struct net_device *orig_wdev)
 281 {
 282         struct net_device *ldev;
 283
 284         if (wdev->type != ARPHRD_IEEE802154 ||
 285             skb->pkt_type == PACKET_OTHERHOST ||
 286             !lowpan_rx_h_check(skb))
 287                 goto drop;
 288
 289         ldev = wdev->ieee802154_ptr->lowpan_dev;
 290         if (!ldev || !netif_running(ldev))
 291                 goto drop;
 292
 293         /* Replacing skb->dev and followed rx handlers will manipulate skb. */
 294         skb = skb_share_check(skb, GFP_ATOMIC);
 295         if (!skb)
 296                 goto out;
 297         skb->dev = ldev;
 298
 299         /* When receive frag1 it's likely that we manipulate the buffer.
 300          * When recevie iphc we manipulate the data buffer. So we need
 301          * to unshare the buffer.
 302          */
 303         if (lowpan_is_frag1(*skb_network_header(skb)) ||
 304             lowpan_is_iphc(*skb_network_header(skb))) {
 305                 skb = skb_unshare(skb, GFP_ATOMIC);
 306                 if (!skb)
 307                         goto out;
 308         }
 309
 310         return lowpan_invoke_rx_handlers(skb);
 311
 312 drop:
 313         kfree_skb(skb);
 314 out:
 315         return NET_RX_DROP;
 316 }
 317
 318 static struct packet_type lowpan_packet_type = {
 319         .type = htons(ETH_P_IEEE802154),
 320         .func = lowpan_rcv,
 321 };
 322
 323 void lowpan_rx_init(void)
 324 {
 325         dev_add_pack(&lowpan_packet_type);
 326 }
 327
 328 void lowpan_rx_exit(void)
 329 {
 330         dev_remove_pack(&lowpan_packet_type);
 331 }