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 /*
  77  * P1K := Phase1(TA, TK, TSC)
  78  * TA = transmitter address (48 bits)
  79  * TK = dot11DefaultKeyValue or dot11KeyMappingValue (128 bits)
  80  * TSC = TKIP sequence counter (48 bits, only 32 msb bits used)
  81  * P1K: 80 bits
  82  */
  83 static void tkip_mixing_phase1(struct ieee80211_key *key, const u8 *ta,
  84                                struct tkip_ctx *ctx, u32 tsc_IV32)
  85 {
  86         int i, j;
  87         const u8 *tk = &key->conf.key[ALG_TKIP_TEMP_ENCR_KEY];
  88         u16 *p1k = ctx->p1k;
  89
  90         p1k[0] = tsc_IV32 & 0xFFFF;
  91         p1k[1] = tsc_IV32 >> 16;
  92         p1k[2] = get_unaligned_le16(ta + 0);
  93         p1k[3] = get_unaligned_le16(ta + 2);
  94         p1k[4] = get_unaligned_le16(ta + 4);
  95
  96         for (i = 0; i < PHASE1_LOOP_COUNT; i++) {
  97                 j = 2 * (i & 1);
  98                 p1k[0] += tkipS(p1k[4] ^ get_unaligned_le16(tk + 0 + j));
  99                 p1k[1] += tkipS(p1k[0] ^ get_unaligned_le16(tk + 4 + j));
 100                 p1k[2] += tkipS(p1k[1] ^ get_unaligned_le16(tk + 8 + j));
 101                 p1k[3] += tkipS(p1k[2] ^ get_unaligned_le16(tk + 12 + j));
 102                 p1k[4] += tkipS(p1k[3] ^ get_unaligned_le16(tk + 0 + j)) + i;
 103         }
 104         ctx->initialized = 1;
 105 }
 106
 107 static void tkip_mixing_phase2(struct ieee80211_key *key, struct tkip_ctx *ctx,
 108                                u16 tsc_IV16, u8 *rc4key)
 109 {
 110         u16 ppk[6];
 111         const u16 *p1k = ctx->p1k;
 112         const u8 *tk = &key->conf.key[ALG_TKIP_TEMP_ENCR_KEY];
 113         int i;
 114
 115         ppk[0] = p1k[0];
 116         ppk[1] = p1k[1];
 117         ppk[2] = p1k[2];
 118         ppk[3] = p1k[3];
 119         ppk[4] = p1k[4];
 120         ppk[5] = p1k[4] + tsc_IV16;
 121
 122         ppk[0] += tkipS(ppk[5] ^ get_unaligned_le16(tk + 0));
 123         ppk[1] += tkipS(ppk[0] ^ get_unaligned_le16(tk + 2));
 124         ppk[2] += tkipS(ppk[1] ^ get_unaligned_le16(tk + 4));
 125         ppk[3] += tkipS(ppk[2] ^ get_unaligned_le16(tk + 6));
 126         ppk[4] += tkipS(ppk[3] ^ get_unaligned_le16(tk + 8));
 127         ppk[5] += tkipS(ppk[4] ^ get_unaligned_le16(tk + 10));
 128         ppk[0] += ror16(ppk[5] ^ get_unaligned_le16(tk + 12), 1);
 129         ppk[1] += ror16(ppk[0] ^ get_unaligned_le16(tk + 14), 1);
 130         ppk[2] += ror16(ppk[1], 1);
 131         ppk[3] += ror16(ppk[2], 1);
 132         ppk[4] += ror16(ppk[3], 1);
 133         ppk[5] += ror16(ppk[4], 1);
 134
 135         rc4key = write_tkip_iv(rc4key, tsc_IV16);
 136         *rc4key++ = ((ppk[5] ^ get_unaligned_le16(tk)) >> 1) & 0xFF;
 137
 138         for (i = 0; i < 6; i++)
 139                 put_unaligned_le16(ppk[i], rc4key + 2 * i);
 140 }
 141
 142 /* Add TKIP IV and Ext. IV at @pos. @iv0, @iv1, and @iv2 are the first octets
 143  * of the IV. Returns pointer to the octet following IVs (i.e., beginning of
 144  * the packet payload). */
 145 u8 *ieee80211_tkip_add_iv(u8 *pos, struct ieee80211_key *key, u16 iv16)
 146 {
 147         pos = write_tkip_iv(pos, iv16);
 148         *pos++ = (key->conf.keyidx << 6) | (1 << 5) /* Ext IV */;
 149         put_unaligned_le32(key->u.tkip.tx.iv32, pos);
 150         return pos + 4;
 151 }
 152
 153 static void ieee80211_tkip_gen_rc4key(struct ieee80211_key *key, u8 *ta,
 154                                u8 *rc4key)
 155 {
 156         /* Calculate per-packet key */
 157         if (key->u.tkip.tx.iv16 == 0 || !key->u.tkip.tx.initialized)
 158                 tkip_mixing_phase1(key, ta, &key->u.tkip.tx, key->u.tkip.tx.iv32);
 159
 160         tkip_mixing_phase2(key, &key->u.tkip.tx, key->u.tkip.tx.iv16, rc4key);
 161 }
 162
 163 void ieee80211_get_tkip_key(struct ieee80211_key_conf *keyconf,
 164                         struct sk_buff *skb, enum ieee80211_tkip_key_type type,
 165                         u8 *outkey)
 166 {
 167         struct ieee80211_key *key = (struct ieee80211_key *)
 168                         container_of(keyconf, struct ieee80211_key, conf);
 169         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 170         u8 *data = (u8 *) hdr;
 171         u16 fc = le16_to_cpu(hdr->frame_control);
 172         int hdr_len = ieee80211_get_hdrlen(fc);
 173         u8 *ta = hdr->addr2;
 174         u16 iv16;
 175         u32 iv32;
 176
 177         iv16 = data[hdr_len + 2] | (data[hdr_len] << 8);
 178         iv32 = get_unaligned_le32(data + hdr_len + 4);
 179
 180 #ifdef CONFIG_TKIP_DEBUG
 181         printk(KERN_DEBUG "TKIP encrypt: iv16 = 0x%04x, iv32 = 0x%08x\n",
 182                         iv16, iv32);
 183
 184         if (iv32 != key->u.tkip.tx.iv32) {
 185                 printk(KERN_DEBUG "skb: iv32 = 0x%08x key: iv32 = 0x%08x\n",
 186                         iv32, key->u.tkip.tx.iv32);
 187                 printk(KERN_DEBUG "Wrap around of iv16 in the middle of a "
 188                         "fragmented packet\n");
 189         }
 190 #endif /* CONFIG_TKIP_DEBUG */
 191
 192         /* Update the p1k only when the iv16 in the packet wraps around, this
 193          * might occur after the wrap around of iv16 in the key in case of
 194          * fragmented packets. */
 195         if (iv16 == 0 || !key->u.tkip.tx.initialized)
 196                 tkip_mixing_phase1(key, ta, &key->u.tkip.tx, iv32);
 197
 198         if (type == IEEE80211_TKIP_P1_KEY) {
 199                 memcpy(outkey, key->u.tkip.tx.p1k, sizeof(u16) * 5);
 200                 return;
 201         }
 202
 203         tkip_mixing_phase2(key, &key->u.tkip.tx, iv16, outkey);
 204 }
 205 EXPORT_SYMBOL(ieee80211_get_tkip_key);
 206
 207 /* Encrypt packet payload with TKIP using @key. @pos is a pointer to the
 208  * beginning of the buffer containing payload. This payload must include
 209  * headroom of eight octets for IV and Ext. IV and taildroom of four octets
 210  * for ICV. @payload_len is the length of payload (_not_ including extra
 211  * headroom and tailroom). @ta is the transmitter addresses. */
 212 void ieee80211_tkip_encrypt_data(struct crypto_blkcipher *tfm,
 213                                  struct ieee80211_key *key,
 214                                  u8 *pos, size_t payload_len, u8 *ta)
 215 {
 216         u8 rc4key[16];
 217
 218         ieee80211_tkip_gen_rc4key(key, ta, rc4key);
 219         pos = ieee80211_tkip_add_iv(pos, key, key->u.tkip.tx.iv16);
 220         ieee80211_wep_encrypt_data(tfm, rc4key, 16, pos, payload_len);
 221 }
 222
 223 /* Decrypt packet payload with TKIP using @key. @pos is a pointer to the
 224  * beginning of the buffer containing IEEE 802.11 header payload, i.e.,
 225  * including IV, Ext. IV, real data, Michael MIC, ICV. @payload_len is the
 226  * length of payload, including IV, Ext. IV, MIC, ICV.  */
 227 int ieee80211_tkip_decrypt_data(struct crypto_blkcipher *tfm,
 228                                 struct ieee80211_key *key,
 229                                 u8 *payload, size_t payload_len, u8 *ta,
 230                                 u8 *ra, int only_iv, int queue,
 231                                 u32 *out_iv32, u16 *out_iv16)
 232 {
 233         u32 iv32;
 234         u32 iv16;
 235         u8 rc4key[16], keyid, *pos = payload;
 236         int res;
 237
 238         if (payload_len < 12)
 239                 return -1;
 240
 241         iv16 = (pos[0] << 8) | pos[2];
 242         keyid = pos[3];
 243         iv32 = get_unaligned_le32(pos + 4);
 244         pos += 8;
 245 #ifdef CONFIG_TKIP_DEBUG
 246         {
 247                 int i;
 248                 printk(KERN_DEBUG "TKIP decrypt: data(len=%zd)", payload_len);
 249                 for (i = 0; i < payload_len; i++)
 250                         printk(" %02x", payload[i]);
 251                 printk("\n");
 252                 printk(KERN_DEBUG "TKIP decrypt: iv16=%04x iv32=%08x\n",
 253                        iv16, iv32);
 254         }
 255 #endif /* CONFIG_TKIP_DEBUG */
 256
 257         if (!(keyid & (1 << 5)))
 258                 return TKIP_DECRYPT_NO_EXT_IV;
 259
 260         if ((keyid >> 6) != key->conf.keyidx)
 261                 return TKIP_DECRYPT_INVALID_KEYIDX;
 262
 263         if (key->u.tkip.rx[queue].initialized &&
 264             (iv32 < key->u.tkip.rx[queue].iv32 ||
 265              (iv32 == key->u.tkip.rx[queue].iv32 &&
 266               iv16 <= key->u.tkip.rx[queue].iv16))) {
 267 #ifdef CONFIG_TKIP_DEBUG
 268                 DECLARE_MAC_BUF(mac);
 269                 printk(KERN_DEBUG "TKIP replay detected for RX frame from "
 270                        "%s (RX IV (%04x,%02x) <= prev. IV (%04x,%02x)\n",
 271                        print_mac(mac, ta),
 272                        iv32, iv16, key->u.tkip.rx[queue].iv32,
 273                        key->u.tkip.rx[queue].iv16);
 274 #endif /* CONFIG_TKIP_DEBUG */
 275                 return TKIP_DECRYPT_REPLAY;
 276         }
 277
 278         if (only_iv) {
 279                 res = TKIP_DECRYPT_OK;
 280                 key->u.tkip.rx[queue].initialized = 1;
 281                 goto done;
 282         }
 283
 284         if (!key->u.tkip.rx[queue].initialized ||
 285             key->u.tkip.rx[queue].iv32 != iv32) {
 286                 /* IV16 wrapped around - perform TKIP phase 1 */
 287                 tkip_mixing_phase1(key, ta, &key->u.tkip.rx[queue], iv32);
 288 #ifdef CONFIG_TKIP_DEBUG
 289                 {
 290                         int i;
 291                         DECLARE_MAC_BUF(mac);
 292                         printk(KERN_DEBUG "TKIP decrypt: Phase1 TA=%s"
 293                                " TK=", print_mac(mac, ta));
 294                         for (i = 0; i < 16; i++)
 295                                 printk("%02x ",
 296                                        key->conf.key[
 297                                                 ALG_TKIP_TEMP_ENCR_KEY + i]);
 298                         printk("\n");
 299                         printk(KERN_DEBUG "TKIP decrypt: P1K=");
 300                         for (i = 0; i < 5; i++)
 301                                 printk("%04x ", key->u.tkip.rx[queue].p1k[i]);
 302                         printk("\n");
 303                 }
 304 #endif /* CONFIG_TKIP_DEBUG */
 305                 if (key->local->ops->update_tkip_key &&
 306                         key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
 307                         u8 bcast[ETH_ALEN] =
 308                                 {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
 309                         u8 *sta_addr = key->sta->addr;
 310
 311                         if (is_multicast_ether_addr(ra))
 312                                 sta_addr = bcast;
 313
 314                         key->local->ops->update_tkip_key(
 315                                 local_to_hw(key->local), &key->conf,
 316                                 sta_addr, iv32, key->u.tkip.rx[queue].p1k);
 317                 }
 318         }
 319
 320         tkip_mixing_phase2(key, &key->u.tkip.rx[queue], iv16, rc4key);
 321 #ifdef CONFIG_TKIP_DEBUG
 322         {
 323                 int i;
 324                 printk(KERN_DEBUG "TKIP decrypt: Phase2 rc4key=");
 325                 for (i = 0; i < 16; i++)
 326                         printk("%02x ", rc4key[i]);
 327                 printk("\n");
 328         }
 329 #endif /* CONFIG_TKIP_DEBUG */
 330
 331         res = ieee80211_wep_decrypt_data(tfm, rc4key, 16, pos, payload_len - 12);
 332  done:
 333         if (res == TKIP_DECRYPT_OK) {
 334                 /*
 335                  * Record previously received IV, will be copied into the
 336                  * key information after MIC verification. It is possible
 337                  * that we don't catch replays of fragments but that's ok
 338                  * because the Michael MIC verication will then fail.
 339                  */
 340                 *out_iv32 = iv32;
 341                 *out_iv16 = iv16;
 342         }
 343
 344         return res;
 345 }