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 <linux/export.h>
  14 #include <asm/unaligned.h>
  15
  16 #include <net/mac80211.h>
  17 #include "driver-ops.h"
  18 #include "key.h"
  19 #include "tkip.h"
  20 #include "wep.h"
  21
  22 #define PHASE1_LOOP_COUNT 8
  23
  24 /*
  25  * 2-byte by 2-byte subset of the full AES S-box table; second part of this
  26  * table is identical to first part but byte-swapped
  27  */
  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 static u16 tkipS(u16 val)
  65 {
  66         return tkip_sbox[val & 0xff] ^ swab16(tkip_sbox[val >> 8]);
  67 }
  68
  69 static u8 *write_tkip_iv(u8 *pos, u16 iv16)
  70 {
  71         *pos++ = iv16 >> 8;
  72         *pos++ = ((iv16 >> 8) | 0x20) & 0x7f;
  73         *pos++ = iv16 & 0xFF;
  74         return pos;
  75 }
  76
  77 /*
  78  * P1K := Phase1(TA, TK, TSC)
  79  * TA = transmitter address (48 bits)
  80  * TK = dot11DefaultKeyValue or dot11KeyMappingValue (128 bits)
  81  * TSC = TKIP sequence counter (48 bits, only 32 msb bits used)
  82  * P1K: 80 bits
  83  */
  84 static void tkip_mixing_phase1(const u8 *tk, struct tkip_ctx *ctx,
  85                                const u8 *ta, u32 tsc_IV32)
  86 {
  87         int i, j;
  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->state = TKIP_STATE_PHASE1_DONE;
 105         ctx->p1k_iv32 = tsc_IV32;
 106 }
 107
 108 static void tkip_mixing_phase2(const u8 *tk, struct tkip_ctx *ctx,
 109                                u16 tsc_IV16, u8 *rc4key)
 110 {
 111         u16 ppk[6];
 112         const u16 *p1k = ctx->p1k;
 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)
 146 {
 147         lockdep_assert_held(&key->u.tkip.txlock);
 148
 149         pos = write_tkip_iv(pos, key->u.tkip.tx.iv16);
 150         *pos++ = (key->conf.keyidx << 6) | (1 << 5) /* Ext IV */;
 151         put_unaligned_le32(key->u.tkip.tx.iv32, pos);
 152         return pos + 4;
 153 }
 154
 155 static void ieee80211_compute_tkip_p1k(struct ieee80211_key *key, u32 iv32)
 156 {
 157         struct ieee80211_sub_if_data *sdata = key->sdata;
 158         struct tkip_ctx *ctx = &key->u.tkip.tx;
 159         const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
 160
 161         lockdep_assert_held(&key->u.tkip.txlock);
 162
 163         /*
 164          * Update the P1K when the IV32 is different from the value it
 165          * had when we last computed it (or when not initialised yet).
 166          * This might flip-flop back and forth if packets are processed
 167          * out-of-order due to the different ACs, but then we have to
 168          * just compute the P1K more often.
 169          */
 170         if (ctx->p1k_iv32 != iv32 || ctx->state == TKIP_STATE_NOT_INIT)
 171                 tkip_mixing_phase1(tk, ctx, sdata->vif.addr, iv32);
 172 }
 173
 174 void ieee80211_get_tkip_p1k_iv(struct ieee80211_key_conf *keyconf,
 175                                u32 iv32, u16 *p1k)
 176 {
 177         struct ieee80211_key *key = (struct ieee80211_key *)
 178                         container_of(keyconf, struct ieee80211_key, conf);
 179         struct tkip_ctx *ctx = &key->u.tkip.tx;
 180
 181         spin_lock_bh(&key->u.tkip.txlock);
 182         ieee80211_compute_tkip_p1k(key, iv32);
 183         memcpy(p1k, ctx->p1k, sizeof(ctx->p1k));
 184         spin_unlock_bh(&key->u.tkip.txlock);
 185 }
 186 EXPORT_SYMBOL(ieee80211_get_tkip_p1k_iv);
 187
 188 void ieee80211_get_tkip_rx_p1k(struct ieee80211_key_conf *keyconf,
 189                                const u8 *ta, u32 iv32, u16 *p1k)
 190 {
 191         const u8 *tk = &keyconf->key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
 192         struct tkip_ctx ctx;
 193
 194         tkip_mixing_phase1(tk, &ctx, ta, iv32);
 195         memcpy(p1k, ctx.p1k, sizeof(ctx.p1k));
 196 }
 197 EXPORT_SYMBOL(ieee80211_get_tkip_rx_p1k);
 198
 199 void ieee80211_get_tkip_p2k(struct ieee80211_key_conf *keyconf,
 200                             struct sk_buff *skb, u8 *p2k)
 201 {
 202         struct ieee80211_key *key = (struct ieee80211_key *)
 203                         container_of(keyconf, struct ieee80211_key, conf);
 204         const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
 205         struct tkip_ctx *ctx = &key->u.tkip.tx;
 206         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 207         const u8 *data = (u8 *)hdr + ieee80211_hdrlen(hdr->frame_control);
 208         u32 iv32 = get_unaligned_le32(&data[4]);
 209         u16 iv16 = data[2] | (data[0] << 8);
 210
 211         spin_lock_bh(&key->u.tkip.txlock);
 212         ieee80211_compute_tkip_p1k(key, iv32);
 213         tkip_mixing_phase2(tk, ctx, iv16, p2k);
 214         spin_unlock_bh(&key->u.tkip.txlock);
 215 }
 216 EXPORT_SYMBOL(ieee80211_get_tkip_p2k);
 217
 218 /*
 219  * Encrypt packet payload with TKIP using @key. @pos is a pointer to the
 220  * beginning of the buffer containing payload. This payload must include
 221  * the IV/Ext.IV and space for (taildroom) four octets for ICV.
 222  * @payload_len is the length of payload (_not_ including IV/ICV length).
 223  * @ta is the transmitter addresses.
 224  */
 225 int ieee80211_tkip_encrypt_data(struct crypto_cipher *tfm,
 226                                 struct ieee80211_key *key,
 227                                 struct sk_buff *skb,
 228                                 u8 *payload, size_t payload_len)
 229 {
 230         u8 rc4key[16];
 231
 232         ieee80211_get_tkip_p2k(&key->conf, skb, rc4key);
 233
 234         return ieee80211_wep_encrypt_data(tfm, rc4key, 16,
 235                                           payload, payload_len);
 236 }
 237
 238 /* Decrypt packet payload with TKIP using @key. @pos is a pointer to the
 239  * beginning of the buffer containing IEEE 802.11 header payload, i.e.,
 240  * including IV, Ext. IV, real data, Michael MIC, ICV. @payload_len is the
 241  * length of payload, including IV, Ext. IV, MIC, ICV.  */
 242 int ieee80211_tkip_decrypt_data(struct crypto_cipher *tfm,
 243                                 struct ieee80211_key *key,
 244                                 u8 *payload, size_t payload_len, u8 *ta,
 245                                 u8 *ra, int only_iv, int queue,
 246                                 u32 *out_iv32, u16 *out_iv16)
 247 {
 248         u32 iv32;
 249         u32 iv16;
 250         u8 rc4key[16], keyid, *pos = payload;
 251         int res;
 252         const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
 253
 254         if (payload_len < 12)
 255                 return -1;
 256
 257         iv16 = (pos[0] << 8) | pos[2];
 258         keyid = pos[3];
 259         iv32 = get_unaligned_le32(pos + 4);
 260         pos += 8;
 261
 262         if (!(keyid & (1 << 5)))
 263                 return TKIP_DECRYPT_NO_EXT_IV;
 264
 265         if ((keyid >> 6) != key->conf.keyidx)
 266                 return TKIP_DECRYPT_INVALID_KEYIDX;
 267
 268         if (key->u.tkip.rx[queue].state != TKIP_STATE_NOT_INIT &&
 269             (iv32 < key->u.tkip.rx[queue].iv32 ||
 270              (iv32 == key->u.tkip.rx[queue].iv32 &&
 271               iv16 <= key->u.tkip.rx[queue].iv16)))
 272                 return TKIP_DECRYPT_REPLAY;
 273
 274         if (only_iv) {
 275                 res = TKIP_DECRYPT_OK;
 276                 key->u.tkip.rx[queue].state = TKIP_STATE_PHASE1_HW_UPLOADED;
 277                 goto done;
 278         }
 279
 280         if (key->u.tkip.rx[queue].state == TKIP_STATE_NOT_INIT ||
 281             key->u.tkip.rx[queue].iv32 != iv32) {
 282                 /* IV16 wrapped around - perform TKIP phase 1 */
 283                 tkip_mixing_phase1(tk, &key->u.tkip.rx[queue], ta, iv32);
 284         }
 285         if (key->local->ops->update_tkip_key &&
 286             key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE &&
 287             key->u.tkip.rx[queue].state != TKIP_STATE_PHASE1_HW_UPLOADED) {
 288                 struct ieee80211_sub_if_data *sdata = key->sdata;
 289
 290                 if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
 291                         sdata = container_of(key->sdata->bss,
 292                                         struct ieee80211_sub_if_data, u.ap);
 293                 drv_update_tkip_key(key->local, sdata, &key->conf, key->sta,
 294                                 iv32, key->u.tkip.rx[queue].p1k);
 295                 key->u.tkip.rx[queue].state = TKIP_STATE_PHASE1_HW_UPLOADED;
 296         }
 297
 298         tkip_mixing_phase2(tk, &key->u.tkip.rx[queue], iv16, rc4key);
 299
 300         res = ieee80211_wep_decrypt_data(tfm, rc4key, 16, pos, payload_len - 12);
 301  done:
 302         if (res == TKIP_DECRYPT_OK) {
 303                 /*
 304                  * Record previously received IV, will be copied into the
 305                  * key information after MIC verification. It is possible
 306                  * that we don't catch replays of fragments but that's ok
 307                  * because the Michael MIC verication will then fail.
 308                  */
 309                 *out_iv32 = iv32;
 310                 *out_iv16 = iv16;
 311         }
 312
 313         return res;
 314 }