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/*

 * Host AP crypt: host-based TKIP encryption implementation for Host AP driver

 *

 * Copyright (c) 2003-2004, Jouni Malinen <j@w1.fi>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation. See README and COPYING for

 * more details.

 */

#include <linux/err.h>

#include <linux/module.h>

#include <linux/init.h>

#include <linux/slab.h>

#include <linux/random.h>

#include <linux/scatterlist.h>

#include <linux/skbuff.h>

#include <linux/netdevice.h>

#include <linux/mm.h>

#include <linux/if_ether.h>

#include <linux/if_arp.h>

#include <asm/string.h>

#include <net/ieee80211.h>

#include <linux/crypto.h>

#include <linux/crc32.h>

MODULE_AUTHOR("Jouni Malinen");

MODULE_DESCRIPTION("Host AP crypt: TKIP");

MODULE_LICENSE("GPL");

struct ieee80211_tkip_data {

#define TKIP_KEY_LEN 32

        u8 key[TKIP_KEY_LEN];

        int key_set;

        u32 tx_iv32;

        u16 tx_iv16;

        u16 tx_ttak[5];

        int tx_phase1_done;

        u32 rx_iv32;

        u16 rx_iv16;

        u16 rx_ttak[5];

        int rx_phase1_done;

        u32 rx_iv32_new;

        u16 rx_iv16_new;

        u32 dot11RSNAStatsTKIPReplays;

        u32 dot11RSNAStatsTKIPICVErrors;

        u32 dot11RSNAStatsTKIPLocalMICFailures;

        int key_idx;

        struct crypto_blkcipher *rx_tfm_arc4;

        struct crypto_hash *rx_tfm_michael;

        struct crypto_blkcipher *tx_tfm_arc4;

        struct crypto_hash *tx_tfm_michael;

        /* scratch buffers for virt_to_page() (crypto API) */

        u8 rx_hdr[16], tx_hdr[16];

        unsigned long flags;

};

static unsigned long ieee80211_tkip_set_flags(unsigned long flags, void *priv)

{

        struct ieee80211_tkip_data *_priv = priv;

        unsigned long old_flags = _priv->flags;

        _priv->flags = flags;

        return old_flags;

}

static unsigned long ieee80211_tkip_get_flags(void *priv)

{

        struct ieee80211_tkip_data *_priv = priv;

        return _priv->flags;

}

static void *ieee80211_tkip_init(int key_idx)

{

        struct ieee80211_tkip_data *priv;

        priv = kzalloc(sizeof(*priv), GFP_ATOMIC);

        if (priv == NULL)

                goto fail;

        priv->key_idx = key_idx;

        priv->tx_tfm_arc4 = crypto_alloc_blkcipher("ecb(arc4)", 0,

                                                CRYPTO_ALG_ASYNC);

        if (IS_ERR(priv->tx_tfm_arc4)) {

                printk(KERN_DEBUG "ieee80211_crypt_tkip: could not allocate "

                       "crypto API arc4\n");

                priv->tx_tfm_arc4 = NULL;

                goto fail;

        }

        priv->tx_tfm_michael = crypto_alloc_hash("michael_mic", 0,

                                                 CRYPTO_ALG_ASYNC);

        if (IS_ERR(priv->tx_tfm_michael)) {

                printk(KERN_DEBUG "ieee80211_crypt_tkip: could not allocate "

                       "crypto API michael_mic\n");

                priv->tx_tfm_michael = NULL;

                goto fail;

        }

        priv->rx_tfm_arc4 = crypto_alloc_blkcipher("ecb(arc4)", 0,

                                                CRYPTO_ALG_ASYNC);

        if (IS_ERR(priv->rx_tfm_arc4)) {

                printk(KERN_DEBUG "ieee80211_crypt_tkip: could not allocate "

                       "crypto API arc4\n");

                priv->rx_tfm_arc4 = NULL;

                goto fail;

        }

        priv->rx_tfm_michael = crypto_alloc_hash("michael_mic", 0,

                                                 CRYPTO_ALG_ASYNC);

        if (IS_ERR(priv->rx_tfm_michael)) {

                printk(KERN_DEBUG "ieee80211_crypt_tkip: could not allocate "

                       "crypto API michael_mic\n");

                priv->rx_tfm_michael = NULL;

                goto fail;

        }

        return priv;

      fail:

        if (priv) {

                if (priv->tx_tfm_michael)

                        crypto_free_hash(priv->tx_tfm_michael);

                if (priv->tx_tfm_arc4)

                        crypto_free_blkcipher(priv->tx_tfm_arc4);

                if (priv->rx_tfm_michael)

                        crypto_free_hash(priv->rx_tfm_michael);

                if (priv->rx_tfm_arc4)

                        crypto_free_blkcipher(priv->rx_tfm_arc4);

                kfree(priv);

        }

        return NULL;

}

static void ieee80211_tkip_deinit(void *priv)

{

        struct ieee80211_tkip_data *_priv = priv;

        if (_priv) {

                if (_priv->tx_tfm_michael)

                        crypto_free_hash(_priv->tx_tfm_michael);

                if (_priv->tx_tfm_arc4)

                        crypto_free_blkcipher(_priv->tx_tfm_arc4);

                if (_priv->rx_tfm_michael)

                        crypto_free_hash(_priv->rx_tfm_michael);

                if (_priv->rx_tfm_arc4)

                        crypto_free_blkcipher(_priv->rx_tfm_arc4);

        }

        kfree(priv);

}

static inline u16 RotR1(u16 val)

{

        return (val >> 1) | (val << 15);

}

static inline u8 Lo8(u16 val)

{

        return val & 0xff;

}

static inline u8 Hi8(u16 val)

{

        return val >> 8;

}

static inline u16 Lo16(u32 val)

{

        return val & 0xffff;

}

static inline u16 Hi16(u32 val)

{

        return val >> 16;

}

static inline u16 Mk16(u8 hi, u8 lo)

{

        return lo | (((u16) hi) << 8);

}

static inline u16 Mk16_le(u16 * v)

{

        return le16_to_cpu(*v);

}

static const u16 Sbox[256] = {

        0xC6A5, 0xF884, 0xEE99, 0xF68D, 0xFF0D, 0xD6BD, 0xDEB1, 0x9154,

        0x6050, 0x0203, 0xCEA9, 0x567D, 0xE719, 0xB562, 0x4DE6, 0xEC9A,

        0x8F45, 0x1F9D, 0x8940, 0xFA87, 0xEF15, 0xB2EB, 0x8EC9, 0xFB0B,

        0x41EC, 0xB367, 0x5FFD, 0x45EA, 0x23BF, 0x53F7, 0xE496, 0x9B5B,

        0x75C2, 0xE11C, 0x3DAE, 0x4C6A, 0x6C5A, 0x7E41, 0xF502, 0x834F,

        0x685C, 0x51F4, 0xD134, 0xF908, 0xE293, 0xAB73, 0x6253, 0x2A3F,

        0x080C, 0x9552, 0x4665, 0x9D5E, 0x3028, 0x37A1, 0x0A0F, 0x2FB5,

        0x0E09, 0x2436, 0x1B9B, 0xDF3D, 0xCD26, 0x4E69, 0x7FCD, 0xEA9F,

        0x121B, 0x1D9E, 0x5874, 0x342E, 0x362D, 0xDCB2, 0xB4EE, 0x5BFB,

        0xA4F6, 0x764D, 0xB761, 0x7DCE, 0x527B, 0xDD3E, 0x5E71, 0x1397,

        0xA6F5, 0xB968, 0x0000, 0xC12C, 0x4060, 0xE31F, 0x79C8, 0xB6ED,

        0xD4BE, 0x8D46, 0x67D9, 0x724B, 0x94DE, 0x98D4, 0xB0E8, 0x854A,

        0xBB6B, 0xC52A, 0x4FE5, 0xED16, 0x86C5, 0x9AD7, 0x6655, 0x1194,

        0x8ACF, 0xE910, 0x0406, 0xFE81, 0xA0F0, 0x7844, 0x25BA, 0x4BE3,

        0xA2F3, 0x5DFE, 0x80C0, 0x058A, 0x3FAD, 0x21BC, 0x7048, 0xF104,

        0x63DF, 0x77C1, 0xAF75, 0x4263, 0x2030, 0xE51A, 0xFD0E, 0xBF6D,

        0x814C, 0x1814, 0x2635, 0xC32F, 0xBEE1, 0x35A2, 0x88CC, 0x2E39,

        0x9357, 0x55F2, 0xFC82, 0x7A47, 0xC8AC, 0xBAE7, 0x322B, 0xE695,

        0xC0A0, 0x1998, 0x9ED1, 0xA37F, 0x4466, 0x547E, 0x3BAB, 0x0B83,

        0x8CCA, 0xC729, 0x6BD3, 0x283C, 0xA779, 0xBCE2, 0x161D, 0xAD76,

        0xDB3B, 0x6456, 0x744E, 0x141E, 0x92DB, 0x0C0A, 0x486C, 0xB8E4,

        0x9F5D, 0xBD6E, 0x43EF, 0xC4A6, 0x39A8, 0x31A4, 0xD337, 0xF28B,

        0xD532, 0x8B43, 0x6E59, 0xDAB7, 0x018C, 0xB164, 0x9CD2, 0x49E0,

        0xD8B4, 0xACFA, 0xF307, 0xCF25, 0xCAAF, 0xF48E, 0x47E9, 0x1018,

        0x6FD5, 0xF088, 0x4A6F, 0x5C72, 0x3824, 0x57F1, 0x73C7, 0x9751,

        0xCB23, 0xA17C, 0xE89C, 0x3E21, 0x96DD, 0x61DC, 0x0D86, 0x0F85,

        0xE090, 0x7C42, 0x71C4, 0xCCAA, 0x90D8, 0x0605, 0xF701, 0x1C12,

        0xC2A3, 0x6A5F, 0xAEF9, 0x69D0, 0x1791, 0x9958, 0x3A27, 0x27B9,

        0xD938, 0xEB13, 0x2BB3, 0x2233, 0xD2BB, 0xA970, 0x0789, 0x33A7,

        0x2DB6, 0x3C22, 0x1592, 0xC920, 0x8749, 0xAAFF, 0x5078, 0xA57A,

        0x038F, 0x59F8, 0x0980, 0x1A17, 0x65DA, 0xD731, 0x84C6, 0xD0B8,

        0x82C3, 0x29B0, 0x5A77, 0x1E11, 0x7BCB, 0xA8FC, 0x6DD6, 0x2C3A,

};

static inline u16 _S_(u16 v)

{

        u16 t = Sbox[Hi8(v)];

        return Sbox[Lo8(v)] ^ ((t << 8) | (t >> 8));

}

#define PHASE1_LOOP_COUNT 8

static void tkip_mixing_phase1(u16 * TTAK, const u8 * TK, const u8 * TA,

                               u32 IV32)

{

        int i, j;

        /* Initialize the 80-bit TTAK from TSC (IV32) and TA[0..5] */

        TTAK[0] = Lo16(IV32);

        TTAK[1] = Hi16(IV32);

        TTAK[2] = Mk16(TA[1], TA[0]);

        TTAK[3] = Mk16(TA[3], TA[2]);

        TTAK[4] = Mk16(TA[5], TA[4]);

        for (i = 0; i < PHASE1_LOOP_COUNT; i++) {

                j = 2 * (i & 1);

                TTAK[0] += _S_(TTAK[4] ^ Mk16(TK[1 + j], TK[0 + j]));

                TTAK[1] += _S_(TTAK[0] ^ Mk16(TK[5 + j], TK[4 + j]));

                TTAK[2] += _S_(TTAK[1] ^ Mk16(TK[9 + j], TK[8 + j]));

                TTAK[3] += _S_(TTAK[2] ^ Mk16(TK[13 + j], TK[12 + j]));

                TTAK[4] += _S_(TTAK[3] ^ Mk16(TK[1 + j], TK[0 + j])) + i;

        }

}

static void tkip_mixing_phase2(u8 * WEPSeed, const u8 * TK, const u16 * TTAK,

                               u16 IV16)

{

        /* Make temporary area overlap WEP seed so that the final copy can be

         * avoided on little endian hosts. */

        u16 *PPK = (u16 *) & WEPSeed[4];

        /* Step 1 - make copy of TTAK and bring in TSC */

        PPK[0] = TTAK[0];

        PPK[1] = TTAK[1];

        PPK[2] = TTAK[2];

        PPK[3] = TTAK[3];

        PPK[4] = TTAK[4];

        PPK[5] = TTAK[4] + IV16;

        /* Step 2 - 96-bit bijective mixing using S-box */

        PPK[0] += _S_(PPK[5] ^ Mk16_le((u16 *) & TK[0]));

        PPK[1] += _S_(PPK[0] ^ Mk16_le((u16 *) & TK[2]));

        PPK[2] += _S_(PPK[1] ^ Mk16_le((u16 *) & TK[4]));

        PPK[3] += _S_(PPK[2] ^ Mk16_le((u16 *) & TK[6]));

        PPK[4] += _S_(PPK[3] ^ Mk16_le((u16 *) & TK[8]));

        PPK[5] += _S_(PPK[4] ^ Mk16_le((u16 *) & TK[10]));

        PPK[0] += RotR1(PPK[5] ^ Mk16_le((u16 *) & TK[12]));

        PPK[1] += RotR1(PPK[0] ^ Mk16_le((u16 *) & TK[14]));

        PPK[2] += RotR1(PPK[1]);

        PPK[3] += RotR1(PPK[2]);

        PPK[4] += RotR1(PPK[3]);

        PPK[5] += RotR1(PPK[4]);

        /* Step 3 - bring in last of TK bits, assign 24-bit WEP IV value

         * WEPSeed[0..2] is transmitted as WEP IV */

        WEPSeed[0] = Hi8(IV16);

        WEPSeed[1] = (Hi8(IV16) | 0x20) & 0x7F;

        WEPSeed[2] = Lo8(IV16);

        WEPSeed[3] = Lo8((PPK[5] ^ Mk16_le((u16 *) & TK[0])) >> 1);

#ifdef __BIG_ENDIAN

        {

                int i;

                for (i = 0; i < 6; i++)

                        PPK[i] = (PPK[i] << 8) | (PPK[i] >> 8);

        }

#endif

}

static int ieee80211_tkip_hdr(struct sk_buff *skb, int hdr_len,

                              u8 * rc4key, int keylen, void *priv)

{

        struct ieee80211_tkip_data *tkey = priv;

        int len;

        u8 *pos;

        struct ieee80211_hdr_4addr *hdr;

        hdr = (struct ieee80211_hdr_4addr *)skb->data;

        if (skb_headroom(skb) < 8 || skb->len < hdr_len)

                return -1;

        if (rc4key == NULL || keylen < 16)

                return -1;

        if (!tkey->tx_phase1_done) {

                tkip_mixing_phase1(tkey->tx_ttak, tkey->key, hdr->addr2,

                                   tkey->tx_iv32);

                tkey->tx_phase1_done = 1;

        }

        tkip_mixing_phase2(rc4key, tkey->key, tkey->tx_ttak, tkey->tx_iv16);

        len = skb->len - hdr_len;

        pos = skb_push(skb, 8);

        memmove(pos, pos + 8, hdr_len);

        pos += hdr_len;

        *pos++ = *rc4key;

        *pos++ = *(rc4key + 1);

        *pos++ = *(rc4key + 2);

        *pos++ = (tkey->key_idx << 6) | (1 << 5) /* Ext IV included */ ;

        *pos++ = tkey->tx_iv32 & 0xff;

        *pos++ = (tkey->tx_iv32 >> 8) & 0xff;

        *pos++ = (tkey->tx_iv32 >> 16) & 0xff;

        *pos++ = (tkey->tx_iv32 >> 24) & 0xff;

        tkey->tx_iv16++;

        if (tkey->tx_iv16 == 0) {

                tkey->tx_phase1_done = 0;

                tkey->tx_iv32++;

        }

        return 8;

}

static int ieee80211_tkip_encrypt(struct sk_buff *skb, int hdr_len, void *priv)

{

        struct ieee80211_tkip_data *tkey = priv;

        struct blkcipher_desc desc = { .tfm = tkey->tx_tfm_arc4 };

        int len;

        u8 rc4key[16], *pos, *icv;

        u32 crc;

        struct scatterlist sg;

        DECLARE_MAC_BUF(mac);

        if (tkey->flags & IEEE80211_CRYPTO_TKIP_COUNTERMEASURES) {

                if (net_ratelimit()) {

                        struct ieee80211_hdr_4addr *hdr =

                            (struct ieee80211_hdr_4addr *)skb->data;

                        printk(KERN_DEBUG ": TKIP countermeasures: dropped "

                               "TX packet to %s\n",

                               print_mac(mac, hdr->addr1));

                }

                return -1;

        }

        if (skb_tailroom(skb) < 4 || skb->len < hdr_len)

                return -1;

        len = skb->len - hdr_len;

        pos = skb->data + hdr_len;

        if ((ieee80211_tkip_hdr(skb, hdr_len, rc4key, 16, priv)) < 0)

                return -1;

        icv = skb_put(skb, 4);

        crc = ~crc32_le(~0, pos, len);

        icv[0] = crc;

        icv[1] = crc >> 8;

        icv[2] = crc >> 16;

        icv[3] = crc >> 24;

        crypto_blkcipher_setkey(tkey->tx_tfm_arc4, rc4key, 16);

        sg_init_one(&sg, pos, len + 4);

        return crypto_blkcipher_encrypt(&desc, &sg, &sg, len + 4);

}

/*

 * deal with seq counter wrapping correctly.

 * refer to timer_after() for jiffies wrapping handling

 */

static inline int tkip_replay_check(u32 iv32_n, u16 iv16_n,

                                    u32 iv32_o, u16 iv16_o)

{

        if ((s32)iv32_n - (s32)iv32_o < 0 ||

            (iv32_n == iv32_o && iv16_n <= iv16_o))

                return 1;

        return 0;

}

static int ieee80211_tkip_decrypt(struct sk_buff *skb, int hdr_len, void *priv)

{

        struct ieee80211_tkip_data *tkey = priv;

        struct blkcipher_desc desc = { .tfm = tkey->rx_tfm_arc4 };

        u8 rc4key[16];

        u8 keyidx, *pos;

        u32 iv32;

        u16 iv16;

        struct ieee80211_hdr_4addr *hdr;

        u8 icv[4];

        u32 crc;

        struct scatterlist sg;

        int plen;

        DECLARE_MAC_BUF(mac);

        hdr = (struct ieee80211_hdr_4addr *)skb->data;

        if (tkey->flags & IEEE80211_CRYPTO_TKIP_COUNTERMEASURES) {

                if (net_ratelimit()) {

                        printk(KERN_DEBUG ": TKIP countermeasures: dropped "

                               "received packet from %s\n",

                               print_mac(mac, hdr->addr2));

                }

                return -1;

        }

        if (skb->len < hdr_len + 8 + 4)

                return -1;

        pos = skb->data + hdr_len;

        keyidx = pos[3];

        if (!(keyidx & (1 << 5))) {

                if (net_ratelimit()) {

                        printk(KERN_DEBUG "TKIP: received packet without ExtIV"

                               " flag from %s\n", print_mac(mac, hdr->addr2));

                }

                return -2;

        }

        keyidx >>= 6;

        if (tkey->key_idx != keyidx) {

                printk(KERN_DEBUG "TKIP: RX tkey->key_idx=%d frame "

                       "keyidx=%d priv=%p\n", tkey->key_idx, keyidx, priv);

                return -6;

        }

        if (!tkey->key_set) {

                if (net_ratelimit()) {

                        printk(KERN_DEBUG "TKIP: received packet from %s"

                               " with keyid=%d that does not have a configured"

                               " key\n", print_mac(mac, hdr->addr2), keyidx);

                }

                return -3;

        }

        iv16 = (pos[0] << 8) | pos[2];

        iv32 = pos[4] | (pos[5] << 8) | (pos[6] << 16) | (pos[7] << 24);

        pos += 8;

        if (tkip_replay_check(iv32, iv16, tkey->rx_iv32, tkey->rx_iv16)) {

                if (ieee80211_ratelimit_debug(IEEE80211_DL_DROP)) {

                        IEEE80211_DEBUG_DROP("TKIP: replay detected: STA=%s"

                               " previous TSC %08x%04x received TSC "

                               "%08x%04x\n", print_mac(mac, hdr->addr2),

                               tkey->rx_iv32, tkey->rx_iv16, iv32, iv16);

                }

                tkey->dot11RSNAStatsTKIPReplays++;

                return -4;

        }

        if (iv32 != tkey->rx_iv32 || !tkey->rx_phase1_done) {

                tkip_mixing_phase1(tkey->rx_ttak, tkey->key, hdr->addr2, iv32);

                tkey->rx_phase1_done = 1;

        }

        tkip_mixing_phase2(rc4key, tkey->key, tkey->rx_ttak, iv16);

        plen = skb->len - hdr_len - 12;

        crypto_blkcipher_setkey(tkey->rx_tfm_arc4, rc4key, 16);

        sg_init_one(&sg, pos, plen + 4);

        if (crypto_blkcipher_decrypt(&desc, &sg, &sg, plen + 4)) {

                if (net_ratelimit()) {

                        printk(KERN_DEBUG ": TKIP: failed to decrypt "

                               "received packet from %s\n",

                               print_mac(mac, hdr->addr2));

                }

                return -7;

        }

        crc = ~crc32_le(~0, pos, plen);

        icv[0] = crc;

        icv[1] = crc >> 8;

        icv[2] = crc >> 16;

        icv[3] = crc >> 24;

        if (memcmp(icv, pos + plen, 4) != 0) {

                if (iv32 != tkey->rx_iv32) {

                        /* Previously cached Phase1 result was already lost, so

                         * it needs to be recalculated for the next packet. */

                        tkey->rx_phase1_done = 0;

                }

                if (ieee80211_ratelimit_debug(IEEE80211_DL_DROP)) {

                        IEEE80211_DEBUG_DROP("TKIP: ICV error detected: STA="

                               "%s\n", print_mac(mac, hdr->addr2));

                }

                tkey->dot11RSNAStatsTKIPICVErrors++;

                return -5;

        }

        /* Update real counters only after Michael MIC verification has

         * completed */

        tkey->rx_iv32_new = iv32;

        tkey->rx_iv16_new = iv16;

        /* Remove IV and ICV */

        memmove(skb->data + 8, skb->data, hdr_len);

        skb_pull(skb, 8);

        skb_trim(skb, skb->len - 4);

        return keyidx;

}

static int michael_mic(struct crypto_hash *tfm_michael, u8 * key, u8 * hdr,

                       u8 * data, size_t data_len, u8 * mic)

{

        struct hash_desc desc;

        struct scatterlist sg[2];

        if (tfm_michael == NULL) {

                printk(KERN_WARNING "michael_mic: tfm_michael == NULL\n");

                return -1;

        }

        sg_init_table(sg, 2);

        sg_set_buf(&sg[0], hdr, 16);

        sg_set_buf(&sg[1], data, data_len);

        if (crypto_hash_setkey(tfm_michael, key, 8))

                return -1;

        desc.tfm = tfm_michael;

        desc.flags = 0;

        return crypto_hash_digest(&desc, sg, data_len + 16, mic);

}

static void michael_mic_hdr(struct sk_buff *skb, u8 * hdr)

{

        struct ieee80211_hdr_4addr *hdr11;

        u16 stype;

        hdr11 = (struct ieee80211_hdr_4addr *)skb->data;

        stype  = WLAN_FC_GET_STYPE(le16_to_cpu(hdr11->frame_ctl));

        switch (le16_to_cpu(hdr11->frame_ctl) &

                (IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS)) {

        case IEEE80211_FCTL_TODS:

                memcpy(hdr, hdr11->addr3, ETH_ALEN);    /* DA */

                memcpy(hdr + ETH_ALEN, hdr11->addr2, ETH_ALEN); /* SA */