net/ieee802154/header_ops.c

   1 /*
   2  * Copyright (C) 2014 Fraunhofer ITWM
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2
   6  * as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * Written by:
  14  * Phoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>
  15  */
  16
  17 #include <linux/ieee802154.h>
  18
  19 #include <net/mac802154.h>
  20 #include <net/ieee802154_netdev.h>
  21
  22 static int
  23 ieee802154_hdr_push_addr(u8 *buf, const struct ieee802154_addr *addr,
  24                          bool omit_pan)
  25 {
  26         int pos = 0;
  27
  28         if (addr->mode == IEEE802154_ADDR_NONE)
  29                 return 0;
  30
  31         if (!omit_pan) {
  32                 memcpy(buf + pos, &addr->pan_id, 2);
  33                 pos += 2;
  34         }
  35
  36         switch (addr->mode) {
  37         case IEEE802154_ADDR_SHORT:
  38                 memcpy(buf + pos, &addr->short_addr, 2);
  39                 pos += 2;
  40                 break;
  41
  42         case IEEE802154_ADDR_LONG:
  43                 memcpy(buf + pos, &addr->extended_addr, IEEE802154_ADDR_LEN);
  44                 pos += IEEE802154_ADDR_LEN;
  45                 break;
  46
  47         default:
  48                 return -EINVAL;
  49         }
  50
  51         return pos;
  52 }
  53
  54 static int
  55 ieee802154_hdr_push_sechdr(u8 *buf, const struct ieee802154_sechdr *hdr)
  56 {
  57         int pos = 5;
  58
  59         memcpy(buf, hdr, 1);
  60         memcpy(buf + 1, &hdr->frame_counter, 4);
  61
  62         switch (hdr->key_id_mode) {
  63         case IEEE802154_SCF_KEY_IMPLICIT:
  64                 return pos;
  65
  66         case IEEE802154_SCF_KEY_INDEX:
  67                 break;
  68
  69         case IEEE802154_SCF_KEY_SHORT_INDEX:
  70                 memcpy(buf + pos, &hdr->short_src, 4);
  71                 pos += 4;
  72                 break;
  73
  74         case IEEE802154_SCF_KEY_HW_INDEX:
  75                 memcpy(buf + pos, &hdr->extended_src, IEEE802154_ADDR_LEN);
  76                 pos += IEEE802154_ADDR_LEN;
  77                 break;
  78         }
  79
  80         buf[pos++] = hdr->key_id;
  81
  82         return pos;
  83 }
  84
  85 int
  86 ieee802154_hdr_push(struct sk_buff *skb, struct ieee802154_hdr *hdr)
  87 {
  88         u8 buf[IEEE802154_MAX_HEADER_LEN];
  89         int pos = 2;
  90         int rc;
  91         struct ieee802154_hdr_fc *fc = &hdr->fc;
  92
  93         buf[pos++] = hdr->seq;
  94
  95         fc->dest_addr_mode = hdr->dest.mode;
  96
  97         rc = ieee802154_hdr_push_addr(buf + pos, &hdr->dest, false);
  98         if (rc < 0)
  99                 return -EINVAL;
 100         pos += rc;
 101
 102         fc->source_addr_mode = hdr->source.mode;
 103
 104         if (hdr->source.pan_id == hdr->dest.pan_id &&
 105             hdr->dest.mode != IEEE802154_ADDR_NONE)
 106                 fc->intra_pan = true;
 107
 108         rc = ieee802154_hdr_push_addr(buf + pos, &hdr->source, fc->intra_pan);
 109         if (rc < 0)
 110                 return -EINVAL;
 111         pos += rc;
 112
 113         if (fc->security_enabled) {
 114                 fc->version = 1;
 115
 116                 rc = ieee802154_hdr_push_sechdr(buf + pos, &hdr->sec);
 117                 if (rc < 0)
 118                         return -EINVAL;
 119
 120                 pos += rc;
 121         }
 122
 123         memcpy(buf, fc, 2);
 124
 125         memcpy(skb_push(skb, pos), buf, pos);
 126
 127         return pos;
 128 }
 129 EXPORT_SYMBOL_GPL(ieee802154_hdr_push);
 130
 131 static int
 132 ieee802154_hdr_get_addr(const u8 *buf, int mode, bool omit_pan,
 133                         struct ieee802154_addr *addr)
 134 {
 135         int pos = 0;
 136
 137         addr->mode = mode;
 138
 139         if (mode == IEEE802154_ADDR_NONE)
 140                 return 0;
 141
 142         if (!omit_pan) {
 143                 memcpy(&addr->pan_id, buf + pos, 2);
 144                 pos += 2;
 145         }
 146
 147         if (mode == IEEE802154_ADDR_SHORT) {
 148                 memcpy(&addr->short_addr, buf + pos, 2);
 149                 return pos + 2;
 150         } else {
 151                 memcpy(&addr->extended_addr, buf + pos, IEEE802154_ADDR_LEN);
 152                 return pos + IEEE802154_ADDR_LEN;
 153         }
 154 }
 155
 156 static int ieee802154_hdr_addr_len(int mode, bool omit_pan)
 157 {
 158         int pan_len = omit_pan ? 0 : 2;
 159
 160         switch (mode) {
 161         case IEEE802154_ADDR_NONE: return 0;
 162         case IEEE802154_ADDR_SHORT: return 2 + pan_len;
 163         case IEEE802154_ADDR_LONG: return IEEE802154_ADDR_LEN + pan_len;
 164         default: return -EINVAL;
 165         }
 166 }
 167
 168 static int
 169 ieee802154_hdr_get_sechdr(const u8 *buf, struct ieee802154_sechdr *hdr)
 170 {
 171         int pos = 5;
 172
 173         memcpy(hdr, buf, 1);
 174         memcpy(&hdr->frame_counter, buf + 1, 4);
 175
 176         switch (hdr->key_id_mode) {
 177         case IEEE802154_SCF_KEY_IMPLICIT:
 178                 return pos;
 179
 180         case IEEE802154_SCF_KEY_INDEX:
 181                 break;
 182
 183         case IEEE802154_SCF_KEY_SHORT_INDEX:
 184                 memcpy(&hdr->short_src, buf + pos, 4);
 185                 pos += 4;
 186                 break;
 187
 188         case IEEE802154_SCF_KEY_HW_INDEX:
 189                 memcpy(&hdr->extended_src, buf + pos, IEEE802154_ADDR_LEN);
 190                 pos += IEEE802154_ADDR_LEN;
 191                 break;
 192         }
 193
 194         hdr->key_id = buf[pos++];
 195
 196         return pos;
 197 }
 198
 199 static int ieee802154_sechdr_lengths[4] = {
 200         [IEEE802154_SCF_KEY_IMPLICIT] = 5,
 201         [IEEE802154_SCF_KEY_INDEX] = 6,
 202         [IEEE802154_SCF_KEY_SHORT_INDEX] = 10,
 203         [IEEE802154_SCF_KEY_HW_INDEX] = 14,
 204 };
 205
 206 static int ieee802154_hdr_sechdr_len(u8 sc)
 207 {
 208         return ieee802154_sechdr_lengths[IEEE802154_SCF_KEY_ID_MODE(sc)];
 209 }
 210
 211 static int ieee802154_hdr_minlen(const struct ieee802154_hdr *hdr)
 212 {
 213         int dlen, slen;
 214
 215         dlen = ieee802154_hdr_addr_len(hdr->fc.dest_addr_mode, false);
 216         slen = ieee802154_hdr_addr_len(hdr->fc.source_addr_mode,
 217                                        hdr->fc.intra_pan);
 218
 219         if (slen < 0 || dlen < 0)
 220                 return -EINVAL;
 221
 222         return 3 + dlen + slen + hdr->fc.security_enabled;
 223 }
 224
 225 static int
 226 ieee802154_hdr_get_addrs(const u8 *buf, struct ieee802154_hdr *hdr)
 227 {
 228         int pos = 0;
 229
 230         pos += ieee802154_hdr_get_addr(buf + pos, hdr->fc.dest_addr_mode,
 231                                        false, &hdr->dest);
 232         pos += ieee802154_hdr_get_addr(buf + pos, hdr->fc.source_addr_mode,
 233                                        hdr->fc.intra_pan, &hdr->source);
 234
 235         if (hdr->fc.intra_pan)
 236                 hdr->source.pan_id = hdr->dest.pan_id;
 237
 238         return pos;
 239 }
 240
 241 int
 242 ieee802154_hdr_pull(struct sk_buff *skb, struct ieee802154_hdr *hdr)
 243 {
 244         int pos = 3, rc;
 245
 246         if (!pskb_may_pull(skb, 3))
 247                 return -EINVAL;
 248
 249         memcpy(hdr, skb->data, 3);
 250
 251         rc = ieee802154_hdr_minlen(hdr);
 252         if (rc < 0 || !pskb_may_pull(skb, rc))
 253                 return -EINVAL;
 254
 255         pos += ieee802154_hdr_get_addrs(skb->data + pos, hdr);
 256
 257         if (hdr->fc.security_enabled) {
 258                 int want = pos + ieee802154_hdr_sechdr_len(skb->data[pos]);
 259
 260                 if (!pskb_may_pull(skb, want))
 261                         return -EINVAL;
 262
 263                 pos += ieee802154_hdr_get_sechdr(skb->data + pos, &hdr->sec);
 264         }
 265
 266         skb_pull(skb, pos);
 267         return pos;
 268 }
 269 EXPORT_SYMBOL_GPL(ieee802154_hdr_pull);
 270
 271 int
 272 ieee802154_hdr_peek_addrs(const struct sk_buff *skb, struct ieee802154_hdr *hdr)
 273 {
 274         const u8 *buf = skb_mac_header(skb);
 275         int pos = 3, rc;
 276
 277         if (buf + 3 > skb_tail_pointer(skb))
 278                 return -EINVAL;
 279
 280         memcpy(hdr, buf, 3);
 281
 282         rc = ieee802154_hdr_minlen(hdr);
 283         if (rc < 0 || buf + rc > skb_tail_pointer(skb))
 284                 return -EINVAL;
 285
 286         pos += ieee802154_hdr_get_addrs(buf + pos, hdr);
 287         return pos;
 288 }
 289 EXPORT_SYMBOL_GPL(ieee802154_hdr_peek_addrs);
 290
 291 int
 292 ieee802154_hdr_peek(const struct sk_buff *skb, struct ieee802154_hdr *hdr)
 293 {
 294         const u8 *buf = skb_mac_header(skb);
 295         int pos;
 296
 297         pos = ieee802154_hdr_peek_addrs(skb, hdr);
 298         if (pos < 0)
 299                 return -EINVAL;
 300
 301         if (hdr->fc.security_enabled) {
 302                 u8 key_id_mode = IEEE802154_SCF_KEY_ID_MODE(*(buf + pos));
 303                 int want = pos + ieee802154_sechdr_lengths[key_id_mode];
 304
 305                 if (buf + want > skb_tail_pointer(skb))
 306                         return -EINVAL;
 307
 308                 pos += ieee802154_hdr_get_sechdr(buf + pos, &hdr->sec);
 309         }
 310
 311         return pos;
 312 }
 313 EXPORT_SYMBOL_GPL(ieee802154_hdr_peek);
 314
 315 int ieee802154_max_payload(const struct ieee802154_hdr *hdr)
 316 {
 317         int hlen = ieee802154_hdr_minlen(hdr);
 318
 319         if (hdr->fc.security_enabled) {
 320                 hlen += ieee802154_sechdr_lengths[hdr->sec.key_id_mode] - 1;
 321                 hlen += ieee802154_sechdr_authtag_len(&hdr->sec);
 322         }
 323
 324         return IEEE802154_MTU - hlen - IEEE802154_MFR_SIZE;
 325 }
 326 EXPORT_SYMBOL_GPL(ieee802154_max_payload);