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
  10 #include <linux/kernel.h>
  11 #include <linux/types.h>
  12 #include <linux/netdevice.h>
  13
  14 #include <net/mac80211.h>
  15 #include "ieee80211_key.h"
  16 #include "tkip.h"
  17 #include "wep.h"
  18
  19
  20 /* TKIP key mixing functions */
  21
  22
  23 #define PHASE1_LOOP_COUNT 8
  24
  25
  26 /* 2-byte by 2-byte subset of the full AES S-box table; second part of this
  27  * table is identical to first part but byte-swapped */
  28 static const u16 tkip_sbox[256] =
  29 {
  30         0xC6A5, 0xF884, 0xEE99, 0xF68D, 0xFF0D, 0xD6BD, 0xDEB1, 0x9154,
  31         0x6050, 0x0203, 0xCEA9, 0x567D, 0xE719, 0xB562, 0x4DE6, 0xEC9A,
  32         0x8F45, 0x1F9D, 0x8940, 0xFA87, 0xEF15, 0xB2EB, 0x8EC9, 0xFB0B,
  33         0x41EC, 0xB367, 0x5FFD, 0x45EA, 0x23BF, 0x53F7, 0xE496, 0x9B5B,
  34         0x75C2, 0xE11C, 0x3DAE, 0x4C6A, 0x6C5A, 0x7E41, 0xF502, 0x834F,
  35         0x685C, 0x51F4, 0xD134, 0xF908, 0xE293, 0xAB73, 0x6253, 0x2A3F,
  36         0x080C, 0x9552, 0x4665, 0x9D5E, 0x3028, 0x37A1, 0x0A0F, 0x2FB5,
  37         0x0E09, 0x2436, 0x1B9B, 0xDF3D, 0xCD26, 0x4E69, 0x7FCD, 0xEA9F,
  38         0x121B, 0x1D9E, 0x5874, 0x342E, 0x362D, 0xDCB2, 0xB4EE, 0x5BFB,
  39         0xA4F6, 0x764D, 0xB761, 0x7DCE, 0x527B, 0xDD3E, 0x5E71, 0x1397,
  40         0xA6F5, 0xB968, 0x0000, 0xC12C, 0x4060, 0xE31F, 0x79C8, 0xB6ED,
  41         0xD4BE, 0x8D46, 0x67D9, 0x724B, 0x94DE, 0x98D4, 0xB0E8, 0x854A,
  42         0xBB6B, 0xC52A, 0x4FE5, 0xED16, 0x86C5, 0x9AD7, 0x6655, 0x1194,
  43         0x8ACF, 0xE910, 0x0406, 0xFE81, 0xA0F0, 0x7844, 0x25BA, 0x4BE3,
  44         0xA2F3, 0x5DFE, 0x80C0, 0x058A, 0x3FAD, 0x21BC, 0x7048, 0xF104,
  45         0x63DF, 0x77C1, 0xAF75, 0x4263, 0x2030, 0xE51A, 0xFD0E, 0xBF6D,
  46         0x814C, 0x1814, 0x2635, 0xC32F, 0xBEE1, 0x35A2, 0x88CC, 0x2E39,
  47         0x9357, 0x55F2, 0xFC82, 0x7A47, 0xC8AC, 0xBAE7, 0x322B, 0xE695,
  48         0xC0A0, 0x1998, 0x9ED1, 0xA37F, 0x4466, 0x547E, 0x3BAB, 0x0B83,
  49         0x8CCA, 0xC729, 0x6BD3, 0x283C, 0xA779, 0xBCE2, 0x161D, 0xAD76,
  50         0xDB3B, 0x6456, 0x744E, 0x141E, 0x92DB, 0x0C0A, 0x486C, 0xB8E4,
  51         0x9F5D, 0xBD6E, 0x43EF, 0xC4A6, 0x39A8, 0x31A4, 0xD337, 0xF28B,
  52         0xD532, 0x8B43, 0x6E59, 0xDAB7, 0x018C, 0xB164, 0x9CD2, 0x49E0,
  53         0xD8B4, 0xACFA, 0xF307, 0xCF25, 0xCAAF, 0xF48E, 0x47E9, 0x1018,
  54         0x6FD5, 0xF088, 0x4A6F, 0x5C72, 0x3824, 0x57F1, 0x73C7, 0x9751,
  55         0xCB23, 0xA17C, 0xE89C, 0x3E21, 0x96DD, 0x61DC, 0x0D86, 0x0F85,
  56         0xE090, 0x7C42, 0x71C4, 0xCCAA, 0x90D8, 0x0605, 0xF701, 0x1C12,
  57         0xC2A3, 0x6A5F, 0xAEF9, 0x69D0, 0x1791, 0x9958, 0x3A27, 0x27B9,
  58         0xD938, 0xEB13, 0x2BB3, 0x2233, 0xD2BB, 0xA970, 0x0789, 0x33A7,
  59         0x2DB6, 0x3C22, 0x1592, 0xC920, 0x8749, 0xAAFF, 0x5078, 0xA57A,
  60         0x038F, 0x59F8, 0x0980, 0x1A17, 0x65DA, 0xD731, 0x84C6, 0xD0B8,
  61         0x82C3, 0x29B0, 0x5A77, 0x1E11, 0x7BCB, 0xA8FC, 0x6DD6, 0x2C3A,
  62 };
  63
  64
  65 static inline u16 Mk16(u8 x, u8 y)
  66 {
  67         return ((u16) x << 8) | (u16) y;
  68 }
  69
  70
  71 static inline u8 Hi8(u16 v)
  72 {
  73         return v >> 8;
  74 }
  75
  76
  77 static inline u8 Lo8(u16 v)
  78 {
  79         return v & 0xff;
  80 }
  81
  82
  83 static inline u16 Hi16(u32 v)
  84 {
  85         return v >> 16;
  86 }
  87
  88
  89 static inline u16 Lo16(u32 v)
  90 {
  91         return v & 0xffff;
  92 }
  93
  94
  95 static inline u16 RotR1(u16 v)
  96 {
  97         return (v >> 1) | ((v & 0x0001) << 15);
  98 }
  99
 100
 101 static inline u16 tkip_S(u16 val)
 102 {
 103         u16 a = tkip_sbox[Hi8(val)];
 104
 105         return tkip_sbox[Lo8(val)] ^ Hi8(a) ^ (Lo8(a) << 8);
 106 }
 107
 108
 109
 110 /* P1K := Phase1(TA, TK, TSC)
 111  * TA = transmitter address (48 bits)
 112  * TK = dot11DefaultKeyValue or dot11KeyMappingValue (128 bits)
 113  * TSC = TKIP sequence counter (48 bits, only 32 msb bits used)
 114  * P1K: 80 bits
 115  */
 116 static void tkip_mixing_phase1(const u8 *ta, const u8 *tk, u32 tsc_IV32,
 117                                u16 *p1k)
 118 {
 119         int i, j;
 120
 121         p1k[0] = Lo16(tsc_IV32);
 122         p1k[1] = Hi16(tsc_IV32);
 123         p1k[2] = Mk16(ta[1], ta[0]);
 124         p1k[3] = Mk16(ta[3], ta[2]);
 125         p1k[4] = Mk16(ta[5], ta[4]);
 126
 127         for (i = 0; i < PHASE1_LOOP_COUNT; i++) {
 128                 j = 2 * (i & 1);
 129                 p1k[0] += tkip_S(p1k[4] ^ Mk16(tk[ 1 + j], tk[ 0 + j]));
 130                 p1k[1] += tkip_S(p1k[0] ^ Mk16(tk[ 5 + j], tk[ 4 + j]));
 131                 p1k[2] += tkip_S(p1k[1] ^ Mk16(tk[ 9 + j], tk[ 8 + j]));
 132                 p1k[3] += tkip_S(p1k[2] ^ Mk16(tk[13 + j], tk[12 + j]));
 133                 p1k[4] += tkip_S(p1k[3] ^ Mk16(tk[ 1 + j], tk[ 0 + j])) + i;
 134         }
 135 }
 136
 137
 138 static void tkip_mixing_phase2(const u16 *p1k, const u8 *tk, u16 tsc_IV16,
 139                                u8 *rc4key)
 140 {
 141         u16 ppk[6];
 142         int i;
 143
 144         ppk[0] = p1k[0];
 145         ppk[1] = p1k[1];
 146         ppk[2] = p1k[2];
 147         ppk[3] = p1k[3];
 148         ppk[4] = p1k[4];
 149         ppk[5] = p1k[4] + tsc_IV16;
 150
 151         ppk[0] += tkip_S(ppk[5] ^ Mk16(tk[ 1], tk[ 0]));
 152         ppk[1] += tkip_S(ppk[0] ^ Mk16(tk[ 3], tk[ 2]));
 153         ppk[2] += tkip_S(ppk[1] ^ Mk16(tk[ 5], tk[ 4]));
 154         ppk[3] += tkip_S(ppk[2] ^ Mk16(tk[ 7], tk[ 6]));
 155         ppk[4] += tkip_S(ppk[3] ^ Mk16(tk[ 9], tk[ 8]));
 156         ppk[5] += tkip_S(ppk[4] ^ Mk16(tk[11], tk[10]));
 157         ppk[0] +=  RotR1(ppk[5] ^ Mk16(tk[13], tk[12]));
 158         ppk[1] +=  RotR1(ppk[0] ^ Mk16(tk[15], tk[14]));
 159         ppk[2] +=  RotR1(ppk[1]);
 160         ppk[3] +=  RotR1(ppk[2]);
 161         ppk[4] +=  RotR1(ppk[3]);
 162         ppk[5] +=  RotR1(ppk[4]);
 163
 164         rc4key[0] = Hi8(tsc_IV16);
 165         rc4key[1] = (Hi8(tsc_IV16) | 0x20) & 0x7f;
 166         rc4key[2] = Lo8(tsc_IV16);
 167         rc4key[3] = Lo8((ppk[5] ^ Mk16(tk[1], tk[0])) >> 1);
 168
 169         for (i = 0; i < 6; i++) {
 170                 rc4key[4 + 2 * i] = Lo8(ppk[i]);
 171                 rc4key[5 + 2 * i] = Hi8(ppk[i]);
 172         }
 173 }
 174
 175
 176 /* Add TKIP IV and Ext. IV at @pos. @iv0, @iv1, and @iv2 are the first octets
 177  * of the IV. Returns pointer to the octet following IVs (i.e., beginning of
 178  * the packet payload). */
 179 u8 * ieee80211_tkip_add_iv(u8 *pos, struct ieee80211_key *key,
 180                            u8 iv0, u8 iv1, u8 iv2)
 181 {
 182         *pos++ = iv0;
 183         *pos++ = iv1;
 184         *pos++ = iv2;
 185         *pos++ = (key->keyidx << 6) | (1 << 5) /* Ext IV */;
 186         *pos++ = key->u.tkip.iv32 & 0xff;
 187         *pos++ = (key->u.tkip.iv32 >> 8) & 0xff;
 188         *pos++ = (key->u.tkip.iv32 >> 16) & 0xff;
 189         *pos++ = (key->u.tkip.iv32 >> 24) & 0xff;
 190         return pos;
 191 }
 192
 193
 194 void ieee80211_tkip_gen_phase1key(struct ieee80211_key *key, u8 *ta,
 195                                   u16 *phase1key)
 196 {
 197         tkip_mixing_phase1(ta, &key->key[ALG_TKIP_TEMP_ENCR_KEY],
 198                            key->u.tkip.iv32, phase1key);
 199 }
 200
 201 void ieee80211_tkip_gen_rc4key(struct ieee80211_key *key, u8 *ta,
 202                                u8 *rc4key)
 203 {
 204         /* Calculate per-packet key */
 205         if (key->u.tkip.iv16 == 0 || !key->u.tkip.tx_initialized) {
 206                 /* IV16 wrapped around - perform TKIP phase 1 */
 207                 tkip_mixing_phase1(ta, &key->key[ALG_TKIP_TEMP_ENCR_KEY],
 208                                    key->u.tkip.iv32, key->u.tkip.p1k);
 209                 key->u.tkip.tx_initialized = 1;
 210         }
 211
 212         tkip_mixing_phase2(key->u.tkip.p1k, &key->key[ALG_TKIP_TEMP_ENCR_KEY],
 213                            key->u.tkip.iv16, rc4key);
 214 }
 215
 216 /* Encrypt packet payload with TKIP using @key. @pos is a pointer to the
 217  * beginning of the buffer containing payload. This payload must include
 218  * headroom of eight octets for IV and Ext. IV and taildroom of four octets
 219  * for ICV. @payload_len is the length of payload (_not_ including extra
 220  * headroom and tailroom). @ta is the transmitter addresses. */
 221 void ieee80211_tkip_encrypt_data(struct crypto_blkcipher *tfm,
 222                                  struct ieee80211_key *key,
 223                                  u8 *pos, size_t payload_len, u8 *ta)
 224 {
 225         u8 rc4key[16];
 226
 227         ieee80211_tkip_gen_rc4key(key, ta, rc4key);
 228         pos = ieee80211_tkip_add_iv(pos, key, rc4key[0], rc4key[1], rc4key[2]);
 229         ieee80211_wep_encrypt_data(tfm, rc4key, 16, pos, payload_len);
 230 }
 231
 232
 233 /* Decrypt packet payload with TKIP using @key. @pos is a pointer to the
 234  * beginning of the buffer containing IEEE 802.11 header payload, i.e.,
 235  * including IV, Ext. IV, real data, Michael MIC, ICV. @payload_len is the
 236  * length of payload, including IV, Ext. IV, MIC, ICV.  */
 237 int ieee80211_tkip_decrypt_data(struct crypto_blkcipher *tfm,
 238                                 struct ieee80211_key *key,
 239                                 u8 *payload, size_t payload_len, u8 *ta,
 240                                 int only_iv, int queue)
 241 {
 242         u32 iv32;
 243         u32 iv16;
 244         u8 rc4key[16], keyid, *pos = payload;
 245         int res;
 246
 247         if (payload_len < 12)
 248                 return -1;
 249
 250         iv16 = (pos[0] << 8) | pos[2];
 251         keyid = pos[3];
 252         iv32 = pos[4] | (pos[5] << 8) | (pos[6] << 16) | (pos[7] << 24);
 253         pos += 8;
 254 #ifdef CONFIG_TKIP_DEBUG
 255         {
 256                 int i;
 257                 printk(KERN_DEBUG "TKIP decrypt: data(len=%zd)", payload_len);
 258                 for (i = 0; i < payload_len; i++)
 259                         printk(" %02x", payload[i]);
 260                 printk("\n");
 261                 printk(KERN_DEBUG "TKIP decrypt: iv16=%04x iv32=%08x\n",
 262                        iv16, iv32);
 263         }
 264 #endif /* CONFIG_TKIP_DEBUG */
 265
 266         if (!(keyid & (1 << 5)))
 267                 return TKIP_DECRYPT_NO_EXT_IV;
 268
 269         if ((keyid >> 6) != key->keyidx)
 270                 return TKIP_DECRYPT_INVALID_KEYIDX;
 271
 272         if (key->u.tkip.rx_initialized[queue] &&
 273             (iv32 < key->u.tkip.iv32_rx[queue] ||
 274              (iv32 == key->u.tkip.iv32_rx[queue] &&
 275               iv16 <= key->u.tkip.iv16_rx[queue]))) {
 276 #ifdef CONFIG_TKIP_DEBUG
 277                 printk(KERN_DEBUG "TKIP replay detected for RX frame from "
 278                        MAC_FMT " (RX IV (%04x,%02x) <= prev. IV (%04x,%02x)\n",
 279                        MAC_ARG(ta),
 280                        iv32, iv16, key->u.tkip.iv32_rx[queue],
 281                        key->u.tkip.iv16_rx[queue]);
 282 #endif /* CONFIG_TKIP_DEBUG */
 283                 return TKIP_DECRYPT_REPLAY;
 284         }
 285
 286         if (only_iv) {
 287                 res = TKIP_DECRYPT_OK;
 288                 key->u.tkip.rx_initialized[queue] = 1;
 289                 goto done;
 290         }
 291
 292         if (!key->u.tkip.rx_initialized[queue] ||
 293             key->u.tkip.iv32_rx[queue] != iv32) {
 294                 key->u.tkip.rx_initialized[queue] = 1;
 295                 /* IV16 wrapped around - perform TKIP phase 1 */
 296                 tkip_mixing_phase1(ta, &key->key[ALG_TKIP_TEMP_ENCR_KEY],
 297                                    iv32, key->u.tkip.p1k_rx[queue]);
 298 #ifdef CONFIG_TKIP_DEBUG
 299                 {
 300                         int i;
 301                         printk(KERN_DEBUG "TKIP decrypt: Phase1 TA=" MAC_FMT
 302                                " TK=", MAC_ARG(ta));
 303                         for (i = 0; i < 16; i++)
 304                                 printk("%02x ",
 305                                        key->key[ALG_TKIP_TEMP_ENCR_KEY + i]);
 306                         printk("\n");
 307                         printk(KERN_DEBUG "TKIP decrypt: P1K=");
 308                         for (i = 0; i < 5; i++)
 309                                 printk("%04x ", key->u.tkip.p1k_rx[queue][i]);
 310                         printk("\n");
 311                 }
 312 #endif /* CONFIG_TKIP_DEBUG */
 313         }
 314
 315         tkip_mixing_phase2(key->u.tkip.p1k_rx[queue],
 316                            &key->key[ALG_TKIP_TEMP_ENCR_KEY],
 317                            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                 /* FIX: these should be updated only after Michael MIC has been
 332                  * verified */
 333                 /* Record previously received IV */
 334                 key->u.tkip.iv32_rx[queue] = iv32;
 335                 key->u.tkip.iv16_rx[queue] = iv16;
 336         }
 337
 338         return res;
 339 }
 340
 341