net/mac80211/tkip.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright 2002-2004, Instant802 Networks, Inc.
   4  * Copyright 2005, Devicescape Software, Inc.
   5  * Copyright (C) 2016 Intel Deutschland GmbH
   6  */
   7 #include <linux/kernel.h>
   8 #include <linux/bitops.h>
   9 #include <linux/types.h>
  10 #include <linux/netdevice.h>
  11 #include <linux/export.h>
  12 #include <asm/unaligned.h>
  13
  14 #include <net/mac80211.h>
  15 #include "driver-ops.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->state = TKIP_STATE_PHASE1_DONE;
 103         ctx->p1k_iv32 = tsc_IV32;
 104 }
 105
 106 static void tkip_mixing_phase2(const u8 *tk, struct tkip_ctx *ctx,
 107                                u16 tsc_IV16, u8 *rc4key)
 108 {
 109         u16 ppk[6];
 110         const u16 *p1k = ctx->p1k;
 111         int i;
 112
 113         ppk[0] = p1k[0];
 114         ppk[1] = p1k[1];
 115         ppk[2] = p1k[2];
 116         ppk[3] = p1k[3];
 117         ppk[4] = p1k[4];
 118         ppk[5] = p1k[4] + tsc_IV16;
 119
 120         ppk[0] += tkipS(ppk[5] ^ get_unaligned_le16(tk + 0));
 121         ppk[1] += tkipS(ppk[0] ^ get_unaligned_le16(tk + 2));
 122         ppk[2] += tkipS(ppk[1] ^ get_unaligned_le16(tk + 4));
 123         ppk[3] += tkipS(ppk[2] ^ get_unaligned_le16(tk + 6));
 124         ppk[4] += tkipS(ppk[3] ^ get_unaligned_le16(tk + 8));
 125         ppk[5] += tkipS(ppk[4] ^ get_unaligned_le16(tk + 10));
 126         ppk[0] += ror16(ppk[5] ^ get_unaligned_le16(tk + 12), 1);
 127         ppk[1] += ror16(ppk[0] ^ get_unaligned_le16(tk + 14), 1);
 128         ppk[2] += ror16(ppk[1], 1);
 129         ppk[3] += ror16(ppk[2], 1);
 130         ppk[4] += ror16(ppk[3], 1);
 131         ppk[5] += ror16(ppk[4], 1);
 132
 133         rc4key = write_tkip_iv(rc4key, tsc_IV16);
 134         *rc4key++ = ((ppk[5] ^ get_unaligned_le16(tk)) >> 1) & 0xFF;
 135
 136         for (i = 0; i < 6; i++)
 137                 put_unaligned_le16(ppk[i], rc4key + 2 * i);
 138 }
 139
 140 /* Add TKIP IV and Ext. IV at @pos. @iv0, @iv1, and @iv2 are the first octets
 141  * of the IV. Returns pointer to the octet following IVs (i.e., beginning of
 142  * the packet payload). */
 143 u8 *ieee80211_tkip_add_iv(u8 *pos, struct ieee80211_key_conf *keyconf, u64 pn)
 144 {
 145         pos = write_tkip_iv(pos, TKIP_PN_TO_IV16(pn));
 146         *pos++ = (keyconf->keyidx << 6) | (1 << 5) /* Ext IV */;
 147         put_unaligned_le32(TKIP_PN_TO_IV32(pn), pos);
 148         return pos + 4;
 149 }
 150 EXPORT_SYMBOL_GPL(ieee80211_tkip_add_iv);
 151
 152 static void ieee80211_compute_tkip_p1k(struct ieee80211_key *key, u32 iv32)
 153 {
 154         struct ieee80211_sub_if_data *sdata = key->sdata;
 155         struct tkip_ctx *ctx = &key->u.tkip.tx;
 156         const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
 157
 158         lockdep_assert_held(&key->u.tkip.txlock);
 159
 160         /*
 161          * Update the P1K when the IV32 is different from the value it
 162          * had when we last computed it (or when not initialised yet).
 163          * This might flip-flop back and forth if packets are processed
 164          * out-of-order due to the different ACs, but then we have to
 165          * just compute the P1K more often.
 166          */
 167         if (ctx->p1k_iv32 != iv32 || ctx->state == TKIP_STATE_NOT_INIT)
 168                 tkip_mixing_phase1(tk, ctx, sdata->vif.addr, iv32);
 169 }
 170
 171 void ieee80211_get_tkip_p1k_iv(struct ieee80211_key_conf *keyconf,
 172                                u32 iv32, u16 *p1k)
 173 {
 174         struct ieee80211_key *key = (struct ieee80211_key *)
 175                         container_of(keyconf, struct ieee80211_key, conf);
 176         struct tkip_ctx *ctx = &key->u.tkip.tx;
 177
 178         spin_lock_bh(&key->u.tkip.txlock);
 179         ieee80211_compute_tkip_p1k(key, iv32);
 180         memcpy(p1k, ctx->p1k, sizeof(ctx->p1k));
 181         spin_unlock_bh(&key->u.tkip.txlock);
 182 }
 183 EXPORT_SYMBOL(ieee80211_get_tkip_p1k_iv);
 184
 185 void ieee80211_get_tkip_rx_p1k(struct ieee80211_key_conf *keyconf,
 186                                const u8 *ta, u32 iv32, u16 *p1k)
 187 {
 188         const u8 *tk = &keyconf->key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
 189         struct tkip_ctx ctx;
 190
 191         tkip_mixing_phase1(tk, &ctx, ta, iv32);
 192         memcpy(p1k, ctx.p1k, sizeof(ctx.p1k));
 193 }
 194 EXPORT_SYMBOL(ieee80211_get_tkip_rx_p1k);
 195
 196 void ieee80211_get_tkip_p2k(struct ieee80211_key_conf *keyconf,
 197                             struct sk_buff *skb, u8 *p2k)
 198 {
 199         struct ieee80211_key *key = (struct ieee80211_key *)
 200                         container_of(keyconf, struct ieee80211_key, conf);
 201         const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
 202         struct tkip_ctx *ctx = &key->u.tkip.tx;
 203         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 204         const u8 *data = (u8 *)hdr + ieee80211_hdrlen(hdr->frame_control);
 205         u32 iv32 = get_unaligned_le32(&data[4]);
 206         u16 iv16 = data[2] | (data[0] << 8);
 207
 208         spin_lock(&key->u.tkip.txlock);
 209         ieee80211_compute_tkip_p1k(key, iv32);
 210         tkip_mixing_phase2(tk, ctx, iv16, p2k);
 211         spin_unlock(&key->u.tkip.txlock);
 212 }
 213 EXPORT_SYMBOL(ieee80211_get_tkip_p2k);
 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  * the IV/Ext.IV and space for (taildroom) four octets for ICV.
 219  * @payload_len is the length of payload (_not_ including IV/ICV length).
 220  * @ta is the transmitter addresses.
 221  */
 222 int ieee80211_tkip_encrypt_data(struct arc4_ctx *ctx,
 223                                 struct ieee80211_key *key,
 224                                 struct sk_buff *skb,
 225                                 u8 *payload, size_t payload_len)
 226 {
 227         u8 rc4key[16];
 228
 229         ieee80211_get_tkip_p2k(&key->conf, skb, rc4key);
 230
 231         return ieee80211_wep_encrypt_data(ctx, rc4key, 16,
 232                                           payload, payload_len);
 233 }
 234
 235 /* Decrypt packet payload with TKIP using @key. @pos is a pointer to the
 236  * beginning of the buffer containing IEEE 802.11 header payload, i.e.,
 237  * including IV, Ext. IV, real data, Michael MIC, ICV. @payload_len is the
 238  * length of payload, including IV, Ext. IV, MIC, ICV.  */
 239 int ieee80211_tkip_decrypt_data(struct arc4_ctx *ctx,
 240                                 struct ieee80211_key *key,
 241                                 u8 *payload, size_t payload_len, u8 *ta,
 242                                 u8 *ra, int only_iv, int queue,
 243                                 u32 *out_iv32, u16 *out_iv16)
 244 {
 245         u32 iv32;
 246         u32 iv16;
 247         u8 rc4key[16], keyid, *pos = payload;
 248         int res;
 249         const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
 250         struct tkip_ctx_rx *rx_ctx = &key->u.tkip.rx[queue];
 251
 252         if (payload_len < 12)
 253                 return -1;
 254
 255         iv16 = (pos[0] << 8) | pos[2];
 256         keyid = pos[3];
 257         iv32 = get_unaligned_le32(pos + 4);
 258         pos += 8;
 259
 260         if (!(keyid & (1 << 5)))
 261                 return TKIP_DECRYPT_NO_EXT_IV;
 262
 263         if ((keyid >> 6) != key->conf.keyidx)
 264                 return TKIP_DECRYPT_INVALID_KEYIDX;
 265
 266         /* Reject replays if the received TSC is smaller than or equal to the
 267          * last received value in a valid message, but with an exception for
 268          * the case where a new key has been set and no valid frame using that
 269          * key has yet received and the local RSC was initialized to 0. This
 270          * exception allows the very first frame sent by the transmitter to be
 271          * accepted even if that transmitter were to use TSC 0 (IEEE 802.11
 272          * described TSC to be initialized to 1 whenever a new key is taken into
 273          * use).
 274          */
 275         if (iv32 < rx_ctx->iv32 ||
 276             (iv32 == rx_ctx->iv32 &&
 277              (iv16 < rx_ctx->iv16 ||
 278               (iv16 == rx_ctx->iv16 &&
 279                (rx_ctx->iv32 || rx_ctx->iv16 ||
 280                 rx_ctx->ctx.state != TKIP_STATE_NOT_INIT)))))
 281                 return TKIP_DECRYPT_REPLAY;
 282
 283         if (only_iv) {
 284                 res = TKIP_DECRYPT_OK;
 285                 rx_ctx->ctx.state = TKIP_STATE_PHASE1_HW_UPLOADED;
 286                 goto done;
 287         }
 288
 289         if (rx_ctx->ctx.state == TKIP_STATE_NOT_INIT ||
 290             rx_ctx->iv32 != iv32) {
 291                 /* IV16 wrapped around - perform TKIP phase 1 */
 292                 tkip_mixing_phase1(tk, &rx_ctx->ctx, ta, iv32);
 293         }
 294         if (key->local->ops->update_tkip_key &&
 295             key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE &&
 296             rx_ctx->ctx.state != TKIP_STATE_PHASE1_HW_UPLOADED) {
 297                 struct ieee80211_sub_if_data *sdata = key->sdata;
 298
 299                 if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
 300                         sdata = container_of(key->sdata->bss,
 301                                         struct ieee80211_sub_if_data, u.ap);
 302                 drv_update_tkip_key(key->local, sdata, &key->conf, key->sta,
 303                                 iv32, rx_ctx->ctx.p1k);
 304                 rx_ctx->ctx.state = TKIP_STATE_PHASE1_HW_UPLOADED;
 305         }
 306
 307         tkip_mixing_phase2(tk, &rx_ctx->ctx, iv16, rc4key);
 308
 309         res = ieee80211_wep_decrypt_data(ctx, rc4key, 16, pos, payload_len - 12);
 310  done:
 311         if (res == TKIP_DECRYPT_OK) {
 312                 /*
 313                  * Record previously received IV, will be copied into the
 314                  * key information after MIC verification. It is possible
 315                  * that we don't catch replays of fragments but that's ok
 316                  * because the Michael MIC verication will then fail.
 317                  */
 318                 *out_iv32 = iv32;
 319                 *out_iv16 = iv16;
 320         }
 321
 322         return res;
 323 }