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 static u8 *write_tkip_iv(u8 *pos, u16 iv16)
  68 {
  69         *pos++ = iv16 >> 8;
  70         *pos++ = ((iv16 >> 8) | 0x20) & 0x7f;
  71         *pos++ = iv16 & 0xFF;
  72         return pos;
  73 }
  74
  75 /*
  76  * P1K := Phase1(TA, TK, TSC)
  77  * TA = transmitter address (48 bits)
  78  * TK = dot11DefaultKeyValue or dot11KeyMappingValue (128 bits)
  79  * TSC = TKIP sequence counter (48 bits, only 32 msb bits used)
  80  * P1K: 80 bits
  81  */
  82 static void tkip_mixing_phase1(const u8 *tk, struct tkip_ctx *ctx,
  83                                const u8 *ta, u32 tsc_IV32)
  84 {
  85         int i, j;
  86         u16 *p1k = ctx->p1k;
  87
  88         p1k[0] = tsc_IV32 & 0xFFFF;
  89         p1k[1] = tsc_IV32 >> 16;
  90         p1k[2] = get_unaligned_le16(ta + 0);
  91         p1k[3] = get_unaligned_le16(ta + 2);
  92         p1k[4] = get_unaligned_le16(ta + 4);
  93
  94         for (i = 0; i < PHASE1_LOOP_COUNT; i++) {
  95                 j = 2 * (i & 1);
  96                 p1k[0] += tkipS(p1k[4] ^ get_unaligned_le16(tk + 0 + j));
  97                 p1k[1] += tkipS(p1k[0] ^ get_unaligned_le16(tk + 4 + j));
  98                 p1k[2] += tkipS(p1k[1] ^ get_unaligned_le16(tk + 8 + j));
  99                 p1k[3] += tkipS(p1k[2] ^ get_unaligned_le16(tk + 12 + j));
 100                 p1k[4] += tkipS(p1k[3] ^ get_unaligned_le16(tk + 0 + j)) + i;
 101         }
 102         ctx->initialized = 1;
 103 }
 104
 105 static void tkip_mixing_phase2(const u8 *tk, struct tkip_ctx *ctx,
 106                                u16 tsc_IV16, u8 *rc4key)
 107 {
 108         u16 ppk[6];
 109         const u16 *p1k = ctx->p1k;
 110         int i;
 111
 112         ppk[0] = p1k[0];
 113         ppk[1] = p1k[1];
 114         ppk[2] = p1k[2];
 115         ppk[3] = p1k[3];
 116         ppk[4] = p1k[4];
 117         ppk[5] = p1k[4] + tsc_IV16;
 118
 119         ppk[0] += tkipS(ppk[5] ^ get_unaligned_le16(tk + 0));
 120         ppk[1] += tkipS(ppk[0] ^ get_unaligned_le16(tk + 2));
 121         ppk[2] += tkipS(ppk[1] ^ get_unaligned_le16(tk + 4));
 122         ppk[3] += tkipS(ppk[2] ^ get_unaligned_le16(tk + 6));
 123         ppk[4] += tkipS(ppk[3] ^ get_unaligned_le16(tk + 8));
 124         ppk[5] += tkipS(ppk[4] ^ get_unaligned_le16(tk + 10));
 125         ppk[0] += ror16(ppk[5] ^ get_unaligned_le16(tk + 12), 1);
 126         ppk[1] += ror16(ppk[0] ^ get_unaligned_le16(tk + 14), 1);
 127         ppk[2] += ror16(ppk[1], 1);
 128         ppk[3] += ror16(ppk[2], 1);
 129         ppk[4] += ror16(ppk[3], 1);
 130         ppk[5] += ror16(ppk[4], 1);
 131
 132         rc4key = write_tkip_iv(rc4key, tsc_IV16);
 133         *rc4key++ = ((ppk[5] ^ get_unaligned_le16(tk)) >> 1) & 0xFF;
 134
 135         for (i = 0; i < 6; i++)
 136                 put_unaligned_le16(ppk[i], rc4key + 2 * i);
 137 }
 138
 139 /* Add TKIP IV and Ext. IV at @pos. @iv0, @iv1, and @iv2 are the first octets
 140  * of the IV. Returns pointer to the octet following IVs (i.e., beginning of
 141  * the packet payload). */
 142 u8 *ieee80211_tkip_add_iv(u8 *pos, struct ieee80211_key *key, u16 iv16)
 143 {
 144         pos = write_tkip_iv(pos, iv16);
 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 void ieee80211_get_tkip_key(struct ieee80211_key_conf *keyconf,
 151                         struct sk_buff *skb, enum ieee80211_tkip_key_type type,
 152                         u8 *outkey)
 153 {
 154         struct ieee80211_key *key = (struct ieee80211_key *)
 155                         container_of(keyconf, struct ieee80211_key, conf);
 156         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 157         u8 *data;
 158         const u8 *tk;
 159         struct tkip_ctx *ctx;
 160         u16 iv16;
 161         u32 iv32;
 162
 163         data = (u8 *)hdr + ieee80211_hdrlen(hdr->frame_control);
 164         iv16 = data[2] | (data[0] << 8);
 165         iv32 = get_unaligned_le32(&data[4]);
 166
 167         tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
 168         ctx = &key->u.tkip.tx;
 169
 170 #ifdef CONFIG_MAC80211_TKIP_DEBUG
 171         printk(KERN_DEBUG "TKIP encrypt: iv16 = 0x%04x, iv32 = 0x%08x\n",
 172                         iv16, iv32);
 173
 174         if (iv32 != ctx->iv32) {
 175                 printk(KERN_DEBUG "skb: iv32 = 0x%08x key: iv32 = 0x%08x\n",
 176                         iv32, ctx->iv32);
 177                 printk(KERN_DEBUG "Wrap around of iv16 in the middle of a "
 178                         "fragmented packet\n");
 179         }
 180 #endif
 181
 182         /* Update the p1k only when the iv16 in the packet wraps around, this
 183          * might occur after the wrap around of iv16 in the key in case of
 184          * fragmented packets. */
 185         if (iv16 == 0 || !ctx->initialized)
 186                 tkip_mixing_phase1(tk, ctx, hdr->addr2, iv32);
 187
 188         if (type == IEEE80211_TKIP_P1_KEY) {
 189                 memcpy(outkey, ctx->p1k, sizeof(u16) * 5);
 190                 return;
 191         }
 192
 193         tkip_mixing_phase2(tk, ctx, iv16, outkey);
 194 }
 195 EXPORT_SYMBOL(ieee80211_get_tkip_key);
 196
 197 /* Encrypt packet payload with TKIP using @key. @pos is a pointer to the
 198  * beginning of the buffer containing payload. This payload must include
 199  * headroom of eight octets for IV and Ext. IV and taildroom of four octets
 200  * for ICV. @payload_len is the length of payload (_not_ including extra
 201  * headroom and tailroom). @ta is the transmitter addresses. */
 202 void ieee80211_tkip_encrypt_data(struct crypto_blkcipher *tfm,
 203                                  struct ieee80211_key *key,
 204                                  u8 *pos, size_t payload_len, u8 *ta)
 205 {
 206         u8 rc4key[16];
 207         struct tkip_ctx *ctx = &key->u.tkip.tx;
 208         const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
 209
 210         /* Calculate per-packet key */
 211         if (ctx->iv16 == 0 || !ctx->initialized)
 212                 tkip_mixing_phase1(tk, ctx, ta, ctx->iv32);
 213
 214         tkip_mixing_phase2(tk, ctx, ctx->iv16, rc4key);
 215
 216         pos = ieee80211_tkip_add_iv(pos, key, key->u.tkip.tx.iv16);
 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         const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
 235
 236         if (payload_len < 12)
 237                 return -1;
 238
 239         iv16 = (pos[0] << 8) | pos[2];
 240         keyid = pos[3];
 241         iv32 = get_unaligned_le32(pos + 4);
 242         pos += 8;
 243 #ifdef CONFIG_MAC80211_TKIP_DEBUG
 244         {
 245                 int i;
 246                 printk(KERN_DEBUG "TKIP decrypt: data(len=%zd)", payload_len);
 247                 for (i = 0; i < payload_len; i++)
 248                         printk(" %02x", payload[i]);
 249                 printk("\n");
 250                 printk(KERN_DEBUG "TKIP decrypt: iv16=%04x iv32=%08x\n",
 251                        iv16, iv32);
 252         }
 253 #endif
 254
 255         if (!(keyid & (1 << 5)))
 256                 return TKIP_DECRYPT_NO_EXT_IV;
 257
 258         if ((keyid >> 6) != key->conf.keyidx)
 259                 return TKIP_DECRYPT_INVALID_KEYIDX;
 260
 261         if (key->u.tkip.rx[queue].initialized &&
 262             (iv32 < key->u.tkip.rx[queue].iv32 ||
 263              (iv32 == key->u.tkip.rx[queue].iv32 &&
 264               iv16 <= key->u.tkip.rx[queue].iv16))) {
 265 #ifdef CONFIG_MAC80211_TKIP_DEBUG
 266                 DECLARE_MAC_BUF(mac);
 267                 printk(KERN_DEBUG "TKIP replay detected for RX frame from "
 268                        "%s (RX IV (%04x,%02x) <= prev. IV (%04x,%02x)\n",
 269                        print_mac(mac, ta),
 270                        iv32, iv16, key->u.tkip.rx[queue].iv32,
 271                        key->u.tkip.rx[queue].iv16);
 272 #endif
 273                 return TKIP_DECRYPT_REPLAY;
 274         }
 275
 276         if (only_iv) {
 277                 res = TKIP_DECRYPT_OK;
 278                 key->u.tkip.rx[queue].initialized = 1;
 279                 goto done;
 280         }
 281
 282         if (!key->u.tkip.rx[queue].initialized ||
 283             key->u.tkip.rx[queue].iv32 != iv32) {
 284                 /* IV16 wrapped around - perform TKIP phase 1 */
 285                 tkip_mixing_phase1(tk, &key->u.tkip.rx[queue], ta, iv32);
 286 #ifdef CONFIG_MAC80211_TKIP_DEBUG
 287                 {
 288                         int i;
 289                         u8 key_offset = NL80211_TKIP_DATA_OFFSET_ENCR_KEY;
 290                         DECLARE_MAC_BUF(mac);
 291                         printk(KERN_DEBUG "TKIP decrypt: Phase1 TA=%s"
 292                                " TK=", print_mac(mac, ta));
 293                         for (i = 0; i < 16; i++)
 294                                 printk("%02x ",
 295                                        key->conf.key[key_offset + i]);
 296                         printk("\n");
 297                         printk(KERN_DEBUG "TKIP decrypt: P1K=");
 298                         for (i = 0; i < 5; i++)
 299                                 printk("%04x ", key->u.tkip.rx[queue].p1k[i]);
 300                         printk("\n");
 301                 }
 302 #endif
 303                 if (key->local->ops->update_tkip_key &&
 304                         key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
 305                         u8 bcast[ETH_ALEN] =
 306                                 {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
 307                         u8 *sta_addr = key->sta->addr;
 308
 309                         if (is_multicast_ether_addr(ra))
 310                                 sta_addr = bcast;
 311
 312                         key->local->ops->update_tkip_key(
 313                                 local_to_hw(key->local), &key->conf,
 314                                 sta_addr, iv32, key->u.tkip.rx[queue].p1k);
 315                 }
 316         }
 317
 318         tkip_mixing_phase2(tk, &key->u.tkip.rx[queue], iv16, rc4key);
 319 #ifdef CONFIG_MAC80211_TKIP_DEBUG
 320         {
 321                 int i;
 322                 printk(KERN_DEBUG "TKIP decrypt: Phase2 rc4key=");
 323                 for (i = 0; i < 16; i++)
 324                         printk("%02x ", rc4key[i]);
 325                 printk("\n");
 326         }
 327 #endif
 328
 329         res = ieee80211_wep_decrypt_data(tfm, rc4key, 16, pos, payload_len - 12);
 330  done:
 331         if (res == TKIP_DECRYPT_OK) {
 332                 /*
 333                  * Record previously received IV, will be copied into the
 334                  * key information after MIC verification. It is possible
 335                  * that we don't catch replays of fragments but that's ok
 336                  * because the Michael MIC verication will then fail.
 337                  */
 338                 *out_iv32 = iv32;
 339                 *out_iv16 = iv16;
 340         }
 341
 342         return res;
 343 }