linux/net/mac80211/tkip.c
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   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 */
  28static 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
  64static u16 tkipS(u16 val)
  65{
  66        return tkip_sbox[val & 0xff] ^ swab16(tkip_sbox[val >> 8]);
  67}
  68
  69static 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 */
  84static 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
 108static 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). */
 145u8 *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
 155static 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
 174void 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        unsigned long flags;
 181
 182        spin_lock_irqsave(&key->u.tkip.txlock, flags);
 183        ieee80211_compute_tkip_p1k(key, iv32);
 184        memcpy(p1k, ctx->p1k, sizeof(ctx->p1k));
 185        spin_unlock_irqrestore(&key->u.tkip.txlock, flags);
 186}
 187EXPORT_SYMBOL(ieee80211_get_tkip_p1k_iv);
 188
 189void ieee80211_get_tkip_rx_p1k(struct ieee80211_key_conf *keyconf,
 190                               const u8 *ta, u32 iv32, u16 *p1k)
 191{
 192        const u8 *tk = &keyconf->key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
 193        struct tkip_ctx ctx;
 194
 195        tkip_mixing_phase1(tk, &ctx, ta, iv32);
 196        memcpy(p1k, ctx.p1k, sizeof(ctx.p1k));
 197}
 198EXPORT_SYMBOL(ieee80211_get_tkip_rx_p1k);
 199
 200void ieee80211_get_tkip_p2k(struct ieee80211_key_conf *keyconf,
 201                            struct sk_buff *skb, u8 *p2k)
 202{
 203        struct ieee80211_key *key = (struct ieee80211_key *)
 204                        container_of(keyconf, struct ieee80211_key, conf);
 205        const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
 206        struct tkip_ctx *ctx = &key->u.tkip.tx;
 207        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 208        const u8 *data = (u8 *)hdr + ieee80211_hdrlen(hdr->frame_control);
 209        u32 iv32 = get_unaligned_le32(&data[4]);
 210        u16 iv16 = data[2] | (data[0] << 8);
 211        unsigned long flags;
 212
 213        spin_lock_irqsave(&key->u.tkip.txlock, flags);
 214        ieee80211_compute_tkip_p1k(key, iv32);
 215        tkip_mixing_phase2(tk, ctx, iv16, p2k);
 216        spin_unlock_irqrestore(&key->u.tkip.txlock, flags);
 217}
 218EXPORT_SYMBOL(ieee80211_get_tkip_p2k);
 219
 220/*
 221 * Encrypt packet payload with TKIP using @key. @pos is a pointer to the
 222 * beginning of the buffer containing payload. This payload must include
 223 * the IV/Ext.IV and space for (taildroom) four octets for ICV.
 224 * @payload_len is the length of payload (_not_ including IV/ICV length).
 225 * @ta is the transmitter addresses.
 226 */
 227int ieee80211_tkip_encrypt_data(struct crypto_cipher *tfm,
 228                                struct ieee80211_key *key,
 229                                struct sk_buff *skb,
 230                                u8 *payload, size_t payload_len)
 231{
 232        u8 rc4key[16];
 233
 234        ieee80211_get_tkip_p2k(&key->conf, skb, rc4key);
 235
 236        return ieee80211_wep_encrypt_data(tfm, rc4key, 16,
 237                                          payload, payload_len);
 238}
 239
 240/* Decrypt packet payload with TKIP using @key. @pos is a pointer to the
 241 * beginning of the buffer containing IEEE 802.11 header payload, i.e.,
 242 * including IV, Ext. IV, real data, Michael MIC, ICV. @payload_len is the
 243 * length of payload, including IV, Ext. IV, MIC, ICV.  */
 244int ieee80211_tkip_decrypt_data(struct crypto_cipher *tfm,
 245                                struct ieee80211_key *key,
 246                                u8 *payload, size_t payload_len, u8 *ta,
 247                                u8 *ra, int only_iv, int queue,
 248                                u32 *out_iv32, u16 *out_iv16)
 249{
 250        u32 iv32;
 251        u32 iv16;
 252        u8 rc4key[16], keyid, *pos = payload;
 253        int res;
 254        const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
 255
 256        if (payload_len < 12)
 257                return -1;
 258
 259        iv16 = (pos[0] << 8) | pos[2];
 260        keyid = pos[3];
 261        iv32 = get_unaligned_le32(pos + 4);
 262        pos += 8;
 263
 264        if (!(keyid & (1 << 5)))
 265                return TKIP_DECRYPT_NO_EXT_IV;
 266
 267        if ((keyid >> 6) != key->conf.keyidx)
 268                return TKIP_DECRYPT_INVALID_KEYIDX;
 269
 270        if (key->u.tkip.rx[queue].state != TKIP_STATE_NOT_INIT &&
 271            (iv32 < key->u.tkip.rx[queue].iv32 ||
 272             (iv32 == key->u.tkip.rx[queue].iv32 &&
 273              iv16 <= key->u.tkip.rx[queue].iv16)))
 274                return TKIP_DECRYPT_REPLAY;
 275
 276        if (only_iv) {
 277                res = TKIP_DECRYPT_OK;
 278                key->u.tkip.rx[queue].state = TKIP_STATE_PHASE1_HW_UPLOADED;
 279                goto done;
 280        }
 281
 282        if (key->u.tkip.rx[queue].state == TKIP_STATE_NOT_INIT ||
 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        }
 287        if (key->local->ops->update_tkip_key &&
 288            key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE &&
 289            key->u.tkip.rx[queue].state != TKIP_STATE_PHASE1_HW_UPLOADED) {
 290                struct ieee80211_sub_if_data *sdata = key->sdata;
 291
 292                if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
 293                        sdata = container_of(key->sdata->bss,
 294                                        struct ieee80211_sub_if_data, u.ap);
 295                drv_update_tkip_key(key->local, sdata, &key->conf, key->sta,
 296                                iv32, key->u.tkip.rx[queue].p1k);
 297                key->u.tkip.rx[queue].state = TKIP_STATE_PHASE1_HW_UPLOADED;
 298        }
 299
 300        tkip_mixing_phase2(tk, &key->u.tkip.rx[queue], iv16, rc4key);
 301
 302        res = ieee80211_wep_decrypt_data(tfm, rc4key, 16, pos, payload_len - 12);
 303 done:
 304        if (res == TKIP_DECRYPT_OK) {
 305                /*
 306                 * Record previously received IV, will be copied into the
 307                 * key information after MIC verification. It is possible
 308                 * that we don't catch replays of fragments but that's ok
 309                 * because the Michael MIC verication will then fail.
 310                 */
 311                *out_iv32 = iv32;
 312                *out_iv16 = iv16;
 313        }
 314
 315        return res;
 316}
 317
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