err.no Git - linux-2.6/blob - net/mac80211/tkip.c

   1 /*
   2  * Copyright 2002-2004, Instant802 Networks, Inc.
   3  * Copyright 2005, Devicescape Software, Inc.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9 #include <linux/kernel.h>
  10 #include <linux/bitops.h>
  11 #include <linux/types.h>
  12 #include <linux/netdevice.h>
  13 #include <asm/unaligned.h>
  14
  15 #include <net/mac80211.h>
  16 #include "key.h"
  17 #include "tkip.h"
  18 #include "wep.h"
  19
  20 #define PHASE1_LOOP_COUNT 8
  21
  22 /*
  23  * 2-byte by 2-byte subset of the full AES S-box table; second part of this
  24  * table is identical to first part but byte-swapped
  25  */
  26 static const u16 tkip_sbox[256] =
  27 {
  28         0xC6A5, 0xF884, 0xEE99, 0xF68D, 0xFF0D, 0xD6BD, 0xDEB1, 0x9154,
  29         0x6050, 0x0203, 0xCEA9, 0x567D, 0xE719, 0xB562, 0x4DE6, 0xEC9A,
  30         0x8F45, 0x1F9D, 0x8940, 0xFA87, 0xEF15, 0xB2EB, 0x8EC9, 0xFB0B,
  31         0x41EC, 0xB367, 0x5FFD, 0x45EA, 0x23BF, 0x53F7, 0xE496, 0x9B5B,
  32         0x75C2, 0xE11C, 0x3DAE, 0x4C6A, 0x6C5A, 0x7E41, 0xF502, 0x834F,
  33         0x685C, 0x51F4, 0xD134, 0xF908, 0xE293, 0xAB73, 0x6253, 0x2A3F,
  34         0x080C, 0x9552, 0x4665, 0x9D5E, 0x3028, 0x37A1, 0x0A0F, 0x2FB5,
  35         0x0E09, 0x2436, 0x1B9B, 0xDF3D, 0xCD26, 0x4E69, 0x7FCD, 0xEA9F,
  36         0x121B, 0x1D9E, 0x5874, 0x342E, 0x362D, 0xDCB2, 0xB4EE, 0x5BFB,
  37         0xA4F6, 0x764D, 0xB761, 0x7DCE, 0x527B, 0xDD3E, 0x5E71, 0x1397,
  38         0xA6F5, 0xB968, 0x0000, 0xC12C, 0x4060, 0xE31F, 0x79C8, 0xB6ED,
  39         0xD4BE, 0x8D46, 0x67D9, 0x724B, 0x94DE, 0x98D4, 0xB0E8, 0x854A,
  40         0xBB6B, 0xC52A, 0x4FE5, 0xED16, 0x86C5, 0x9AD7, 0x6655, 0x1194,
  41         0x8ACF, 0xE910, 0x0406, 0xFE81, 0xA0F0, 0x7844, 0x25BA, 0x4BE3,
  42         0xA2F3, 0x5DFE, 0x80C0, 0x058A, 0x3FAD, 0x21BC, 0x7048, 0xF104,
  43         0x63DF, 0x77C1, 0xAF75, 0x4263, 0x2030, 0xE51A, 0xFD0E, 0xBF6D,
  44         0x814C, 0x1814, 0x2635, 0xC32F, 0xBEE1, 0x35A2, 0x88CC, 0x2E39,
  45         0x9357, 0x55F2, 0xFC82, 0x7A47, 0xC8AC, 0xBAE7, 0x322B, 0xE695,
  46         0xC0A0, 0x1998, 0x9ED1, 0xA37F, 0x4466, 0x547E, 0x3BAB, 0x0B83,
  47         0x8CCA, 0xC729, 0x6BD3, 0x283C, 0xA779, 0xBCE2, 0x161D, 0xAD76,
  48         0xDB3B, 0x6456, 0x744E, 0x141E, 0x92DB, 0x0C0A, 0x486C, 0xB8E4,
  49         0x9F5D, 0xBD6E, 0x43EF, 0xC4A6, 0x39A8, 0x31A4, 0xD337, 0xF28B,
  50         0xD532, 0x8B43, 0x6E59, 0xDAB7, 0x018C, 0xB164, 0x9CD2, 0x49E0,
  51         0xD8B4, 0xACFA, 0xF307, 0xCF25, 0xCAAF, 0xF48E, 0x47E9, 0x1018,
  52         0x6FD5, 0xF088, 0x4A6F, 0x5C72, 0x3824, 0x57F1, 0x73C7, 0x9751,
  53         0xCB23, 0xA17C, 0xE89C, 0x3E21, 0x96DD, 0x61DC, 0x0D86, 0x0F85,
  54         0xE090, 0x7C42, 0x71C4, 0xCCAA, 0x90D8, 0x0605, 0xF701, 0x1C12,
  55         0xC2A3, 0x6A5F, 0xAEF9, 0x69D0, 0x1791, 0x9958, 0x3A27, 0x27B9,
  56         0xD938, 0xEB13, 0x2BB3, 0x2233, 0xD2BB, 0xA970, 0x0789, 0x33A7,
  57         0x2DB6, 0x3C22, 0x1592, 0xC920, 0x8749, 0xAAFF, 0x5078, 0xA57A,
  58         0x038F, 0x59F8, 0x0980, 0x1A17, 0x65DA, 0xD731, 0x84C6, 0xD0B8,
  59         0x82C3, 0x29B0, 0x5A77, 0x1E11, 0x7BCB, 0xA8FC, 0x6DD6, 0x2C3A,
  60 };
  61
  62 static u16 tkipS(u16 val)
  63 {
  64         return tkip_sbox[val & 0xff] ^ swab16(tkip_sbox[val >> 8]);
  65 }
  66
  67 /*
  68  * P1K := Phase1(TA, TK, TSC)
  69  * TA = transmitter address (48 bits)
  70  * TK = dot11DefaultKeyValue or dot11KeyMappingValue (128 bits)
  71  * TSC = TKIP sequence counter (48 bits, only 32 msb bits used)
  72  * P1K: 80 bits
  73  */
  74 static void tkip_mixing_phase1(struct ieee80211_key *key, const u8 *ta,
  75                                struct tkip_ctx *ctx, u32 tsc_IV32)
  76 {
  77         int i, j;
  78         const u8 *tk = &key->conf.key[ALG_TKIP_TEMP_ENCR_KEY];
  79         u16 *p1k = ctx->p1k;
  80
  81         p1k[0] = tsc_IV32 & 0xFFFF;
  82         p1k[1] = tsc_IV32 >> 16;
  83         p1k[2] = get_unaligned_le16(ta + 0);
  84         p1k[3] = get_unaligned_le16(ta + 2);
  85         p1k[4] = get_unaligned_le16(ta + 4);
  86
  87         for (i = 0; i < PHASE1_LOOP_COUNT; i++) {
  88                 j = 2 * (i & 1);
  89                 p1k[0] += tkipS(p1k[4] ^ get_unaligned_le16(tk + 0 + j));
  90                 p1k[1] += tkipS(p1k[0] ^ get_unaligned_le16(tk + 4 + j));
  91                 p1k[2] += tkipS(p1k[1] ^ get_unaligned_le16(tk + 8 + j));
  92                 p1k[3] += tkipS(p1k[2] ^ get_unaligned_le16(tk + 12 + j));
  93                 p1k[4] += tkipS(p1k[3] ^ get_unaligned_le16(tk + 0 + j)) + i;
  94         }
  95         ctx->initialized = 1;
  96 }
  97
  98 static void tkip_mixing_phase2(struct ieee80211_key *key, struct tkip_ctx *ctx,
  99                                u16 tsc_IV16, u8 *rc4key)
 100 {
 101         u16 ppk[6];
 102         const u16 *p1k = ctx->p1k;
 103         const u8 *tk = &key->conf.key[ALG_TKIP_TEMP_ENCR_KEY];
 104         int i;
 105
 106         ppk[0] = p1k[0];
 107         ppk[1] = p1k[1];
 108         ppk[2] = p1k[2];
 109         ppk[3] = p1k[3];
 110         ppk[4] = p1k[4];
 111         ppk[5] = p1k[4] + tsc_IV16;
 112
 113         ppk[0] += tkipS(ppk[5] ^ get_unaligned_le16(tk + 0));
 114         ppk[1] += tkipS(ppk[0] ^ get_unaligned_le16(tk + 2));
 115         ppk[2] += tkipS(ppk[1] ^ get_unaligned_le16(tk + 4));
 116         ppk[3] += tkipS(ppk[2] ^ get_unaligned_le16(tk + 6));
 117         ppk[4] += tkipS(ppk[3] ^ get_unaligned_le16(tk + 8));
 118         ppk[5] += tkipS(ppk[4] ^ get_unaligned_le16(tk + 10));
 119         ppk[0] += ror16(ppk[5] ^ get_unaligned_le16(tk + 12), 1);
 120         ppk[1] += ror16(ppk[0] ^ get_unaligned_le16(tk + 14), 1);
 121         ppk[2] += ror16(ppk[1], 1);
 122         ppk[3] += ror16(ppk[2], 1);
 123         ppk[4] += ror16(ppk[3], 1);
 124         ppk[5] += ror16(ppk[4], 1);
 125
 126         rc4key[0] = tsc_IV16 >> 8;
 127         rc4key[1] = ((tsc_IV16 >> 8) | 0x20) & 0x7f;
 128         rc4key[2] = tsc_IV16 & 0xFF;
 129         rc4key[3] = ((ppk[5] ^ get_unaligned_le16(tk)) >> 1) & 0xFF;
 130
 131         rc4key += 4;
 132         for (i = 0; i < 6; i++)
 133                 put_unaligned_le16(ppk[i], rc4key + 2 * i);
 134 }
 135
 136 /* Add TKIP IV and Ext. IV at @pos. @iv0, @iv1, and @iv2 are the first octets
 137  * of the IV. Returns pointer to the octet following IVs (i.e., beginning of
 138  * the packet payload). */
 139 u8 *ieee80211_tkip_add_iv(u8 *pos, struct ieee80211_key *key,
 140                            u8 iv0, u8 iv1, u8 iv2)
 141 {
 142         *pos++ = iv0;
 143         *pos++ = iv1;
 144         *pos++ = iv2;
 145         *pos++ = (key->conf.keyidx << 6) | (1 << 5) /* Ext IV */;
 146         put_unaligned_le32(key->u.tkip.tx.iv32, pos);
 147         return pos + 4;
 148 }
 149
 150 static void ieee80211_tkip_gen_rc4key(struct ieee80211_key *key, u8 *ta,
 151                                u8 *rc4key)
 152 {
 153         /* Calculate per-packet key */
 154         if (key->u.tkip.tx.iv16 == 0 || !key->u.tkip.tx.initialized)
 155                 tkip_mixing_phase1(key, ta, &key->u.tkip.tx, key->u.tkip.tx.iv32);
 156
 157         tkip_mixing_phase2(key, &key->u.tkip.tx, key->u.tkip.tx.iv16, rc4key);
 158 }
 159
 160 void ieee80211_get_tkip_key(struct ieee80211_key_conf *keyconf,
 161                         struct sk_buff *skb, enum ieee80211_tkip_key_type type,
 162                         u8 *outkey)
 163 {
 164         struct ieee80211_key *key = (struct ieee80211_key *)
 165                         container_of(keyconf, struct ieee80211_key, conf);
 166         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 167         u8 *data = (u8 *) hdr;
 168         u16 fc = le16_to_cpu(hdr->frame_control);
 169         int hdr_len = ieee80211_get_hdrlen(fc);
 170         u8 *ta = hdr->addr2;
 171         u16 iv16;
 172         u32 iv32;
 173
 174         iv16 = data[hdr_len + 2] | (data[hdr_len] << 8);
 175         iv32 = get_unaligned_le32(data + hdr_len + 4);
 176
 177 #ifdef CONFIG_TKIP_DEBUG
 178         printk(KERN_DEBUG "TKIP encrypt: iv16 = 0x%04x, iv32 = 0x%08x\n",
 179                         iv16, iv32);
 180
 181         if (iv32 != key->u.tkip.tx.iv32) {
 182                 printk(KERN_DEBUG "skb: iv32 = 0x%08x key: iv32 = 0x%08x\n",
 183                         iv32, key->u.tkip.tx.iv32);
 184                 printk(KERN_DEBUG "Wrap around of iv16 in the middle of a "
 185                         "fragmented packet\n");
 186         }
 187 #endif /* CONFIG_TKIP_DEBUG */
 188
 189         /* Update the p1k only when the iv16 in the packet wraps around, this
 190          * might occur after the wrap around of iv16 in the key in case of
 191          * fragmented packets. */
 192         if (iv16 == 0 || !key->u.tkip.tx.initialized)
 193                 tkip_mixing_phase1(key, ta, &key->u.tkip.tx, iv32);
 194
 195         if (type == IEEE80211_TKIP_P1_KEY) {
 196                 memcpy(outkey, key->u.tkip.tx.p1k, sizeof(u16) * 5);
 197                 return;
 198         }
 199
 200         tkip_mixing_phase2(key, &key->u.tkip.tx, iv16, outkey);
 201 }
 202 EXPORT_SYMBOL(ieee80211_get_tkip_key);
 203
 204 /* Encrypt packet payload with TKIP using @key. @pos is a pointer to the
 205  * beginning of the buffer containing payload. This payload must include
 206  * headroom of eight octets for IV and Ext. IV and taildroom of four octets
 207  * for ICV. @payload_len is the length of payload (_not_ including extra
 208  * headroom and tailroom). @ta is the transmitter addresses. */
 209 void ieee80211_tkip_encrypt_data(struct crypto_blkcipher *tfm,
 210                                  struct ieee80211_key *key,
 211                                  u8 *pos, size_t payload_len, u8 *ta)
 212 {
 213         u8 rc4key[16];
 214
 215         ieee80211_tkip_gen_rc4key(key, ta, rc4key);
 216         pos = ieee80211_tkip_add_iv(pos, key, rc4key[0], rc4key[1], rc4key[2]);
 217         ieee80211_wep_encrypt_data(tfm, rc4key, 16, pos, payload_len);
 218 }
 219
 220 /* Decrypt packet payload with TKIP using @key. @pos is a pointer to the
 221  * beginning of the buffer containing IEEE 802.11 header payload, i.e.,
 222  * including IV, Ext. IV, real data, Michael MIC, ICV. @payload_len is the
 223  * length of payload, including IV, Ext. IV, MIC, ICV.  */
 224 int ieee80211_tkip_decrypt_data(struct crypto_blkcipher *tfm,
 225                                 struct ieee80211_key *key,
 226                                 u8 *payload, size_t payload_len, u8 *ta,
 227                                 u8 *ra, int only_iv, int queue,
 228                                 u32 *out_iv32, u16 *out_iv16)
 229 {
 230         u32 iv32;
 231         u32 iv16;
 232         u8 rc4key[16], keyid, *pos = payload;
 233         int res;
 234
 235         if (payload_len < 12)
 236                 return -1;
 237
 238         iv16 = (pos[0] << 8) | pos[2];
 239         keyid = pos[3];
 240         iv32 = get_unaligned_le32(pos + 4);
 241         pos += 8;
 242 #ifdef CONFIG_TKIP_DEBUG
 243         {
 244                 int i;
 245                 printk(KERN_DEBUG "TKIP decrypt: data(len=%zd)", payload_len);
 246                 for (i = 0; i < payload_len; i++)
 247                         printk(" %02x", payload[i]);
 248                 printk("\n");
 249                 printk(KERN_DEBUG "TKIP decrypt: iv16=%04x iv32=%08x\n",
 250                        iv16, iv32);
 251         }
 252 #endif /* CONFIG_TKIP_DEBUG */
 253
 254         if (!(keyid & (1 << 5)))
 255                 return TKIP_DECRYPT_NO_EXT_IV;
 256
 257         if ((keyid >> 6) != key->conf.keyidx)
 258                 return TKIP_DECRYPT_INVALID_KEYIDX;
 259
 260         if (key->u.tkip.rx[queue].initialized &&
 261             (iv32 < key->u.tkip.rx[queue].iv32 ||
 262              (iv32 == key->u.tkip.rx[queue].iv32 &&
 263               iv16 <= key->u.tkip.rx[queue].iv16))) {
 264 #ifdef CONFIG_TKIP_DEBUG
 265                 DECLARE_MAC_BUF(mac);
 266                 printk(KERN_DEBUG "TKIP replay detected for RX frame from "
 267                        "%s (RX IV (%04x,%02x) <= prev. IV (%04x,%02x)\n",
 268                        print_mac(mac, ta),
 269                        iv32, iv16, key->u.tkip.rx[queue].iv32,
 270                        key->u.tkip.rx[queue].iv16);
 271 #endif /* CONFIG_TKIP_DEBUG */
 272                 return TKIP_DECRYPT_REPLAY;
 273         }
 274
 275         if (only_iv) {
 276                 res = TKIP_DECRYPT_OK;
 277                 key->u.tkip.rx[queue].initialized = 1;
 278                 goto done;
 279         }
 280
 281         if (!key->u.tkip.rx[queue].initialized ||
 282             key->u.tkip.rx[queue].iv32 != iv32) {
 283                 /* IV16 wrapped around - perform TKIP phase 1 */
 284                 tkip_mixing_phase1(key, ta, &key->u.tkip.rx[queue], iv32);
 285 #ifdef CONFIG_TKIP_DEBUG
 286                 {
 287                         int i;
 288                         DECLARE_MAC_BUF(mac);
 289                         printk(KERN_DEBUG "TKIP decrypt: Phase1 TA=%s"
 290                                " TK=", print_mac(mac, ta));
 291                         for (i = 0; i < 16; i++)
 292                                 printk("%02x ",
 293                                        key->conf.key[
 294                                                 ALG_TKIP_TEMP_ENCR_KEY + i]);
 295                         printk("\n");
 296                         printk(KERN_DEBUG "TKIP decrypt: P1K=");
 297                         for (i = 0; i < 5; i++)
 298                                 printk("%04x ", key->u.tkip.rx[queue].p1k[i]);
 299                         printk("\n");
 300                 }
 301 #endif /* CONFIG_TKIP_DEBUG */
 302                 if (key->local->ops->update_tkip_key &&
 303                         key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
 304                         u8 bcast[ETH_ALEN] =
 305                                 {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
 306                         u8 *sta_addr = key->sta->addr;
 307
 308                         if (is_multicast_ether_addr(ra))
 309                                 sta_addr = bcast;
 310
 311                         key->local->ops->update_tkip_key(
 312                                 local_to_hw(key->local), &key->conf,
 313                                 sta_addr, iv32, key->u.tkip.rx[queue].p1k);
 314                 }
 315         }
 316
 317         tkip_mixing_phase2(key, &key->u.tkip.rx[queue], iv16, rc4key);
 318 #ifdef CONFIG_TKIP_DEBUG
 319         {
 320                 int i;
 321                 printk(KERN_DEBUG "TKIP decrypt: Phase2 rc4key=");
 322                 for (i = 0; i < 16; i++)
 323                         printk("%02x ", rc4key[i]);
 324                 printk("\n");
 325         }
 326 #endif /* CONFIG_TKIP_DEBUG */
 327
 328         res = ieee80211_wep_decrypt_data(tfm, rc4key, 16, pos, payload_len - 12);
 329  done:
 330         if (res == TKIP_DECRYPT_OK) {
 331                 /*
 332                  * Record previously received IV, will be copied into the
 333                  * key information after MIC verification. It is possible
 334                  * that we don't catch replays of fragments but that's ok
 335                  * because the Michael MIC verication will then fail.
 336                  */
 337                 *out_iv32 = iv32;
 338                 *out_iv16 = iv16;
 339         }
 340
 341         return res;
 342 }