LXR linux/net/mac80211/aes

   1/*
   2 * AES-128-CMAC with TLen 16 for IEEE 802.11w BIP
   3 * Copyright 2008, Jouni Malinen <j@w1.fi>
   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
  10#include <linux/kernel.h>
  11#include <linux/types.h>
  12#include <linux/crypto.h>
  13#include <linux/export.h>
  14#include <linux/err.h>
  15#include <crypto/aes.h>
  16
  17#include <net/mac80211.h>
  18#include "key.h"
  19#include "aes_cmac.h"
  20
  21#define AES_CMAC_KEY_LEN 16
  22#define CMAC_TLEN 8 /* CMAC TLen = 64 bits (8 octets) */
  23#define AAD_LEN 20
  24
  25
  26static void gf_mulx(u8 *pad)
  27{
  28        int i, carry;
  29
  30        carry = pad[0] & 0x80;
  31        for (i = 0; i < AES_BLOCK_SIZE - 1; i++)
  32                pad[i] = (pad[i] << 1) | (pad[i + 1] >> 7);
  33        pad[AES_BLOCK_SIZE - 1] <<= 1;
  34        if (carry)
  35                pad[AES_BLOCK_SIZE - 1] ^= 0x87;
  36}
  37
  38
  39static void aes_128_cmac_vector(struct crypto_cipher *tfm, size_t num_elem,
  40                                const u8 *addr[], const size_t *len, u8 *mac)
  41{
  42        u8 cbc[AES_BLOCK_SIZE], pad[AES_BLOCK_SIZE];
  43        const u8 *pos, *end;
  44        size_t i, e, left, total_len;
  45
  46        memset(cbc, 0, AES_BLOCK_SIZE);
  47
  48        total_len = 0;
  49        for (e = 0; e < num_elem; e++)
  50                total_len += len[e];
  51        left = total_len;
  52
  53        e = 0;
  54        pos = addr[0];
  55        end = pos + len[0];
  56
  57        while (left >= AES_BLOCK_SIZE) {
  58                for (i = 0; i < AES_BLOCK_SIZE; i++) {
  59                        cbc[i] ^= *pos++;
  60                        if (pos >= end) {
  61                                e++;
  62                                pos = addr[e];
  63                                end = pos + len[e];
  64                        }
  65                }
  66                if (left > AES_BLOCK_SIZE)
  67                        crypto_cipher_encrypt_one(tfm, cbc, cbc);
  68                left -= AES_BLOCK_SIZE;
  69        }
  70
  71        memset(pad, 0, AES_BLOCK_SIZE);
  72        crypto_cipher_encrypt_one(tfm, pad, pad);
  73        gf_mulx(pad);
  74
  75        if (left || total_len == 0) {
  76                for (i = 0; i < left; i++) {
  77                        cbc[i] ^= *pos++;
  78                        if (pos >= end) {
  79                                e++;
  80                                pos = addr[e];
  81                                end = pos + len[e];
  82                        }
  83                }
  84                cbc[left] ^= 0x80;
  85                gf_mulx(pad);
  86        }
  87
  88        for (i = 0; i < AES_BLOCK_SIZE; i++)
  89                pad[i] ^= cbc[i];
  90        crypto_cipher_encrypt_one(tfm, pad, pad);
  91        memcpy(mac, pad, CMAC_TLEN);
  92}
  93
  94
  95void ieee80211_aes_cmac(struct crypto_cipher *tfm, const u8 *aad,
  96                        const u8 *data, size_t data_len, u8 *mic)
  97{
  98        const u8 *addr[3];
  99        size_t len[3];
 100        u8 zero[CMAC_TLEN];
 101
 102        memset(zero, 0, CMAC_TLEN);
 103        addr[0] = aad;
 104        len[0] = AAD_LEN;
 105        addr[1] = data;
 106        len[1] = data_len - CMAC_TLEN;
 107        addr[2] = zero;
 108        len[2] = CMAC_TLEN;
 109
 110        aes_128_cmac_vector(tfm, 3, addr, len, mic);
 111}
 112
 113
 114struct crypto_cipher * ieee80211_aes_cmac_key_setup(const u8 key[])
 115{
 116        struct crypto_cipher *tfm;
 117
 118        tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
 119        if (!IS_ERR(tfm))
 120                crypto_cipher_setkey(tfm, key, AES_CMAC_KEY_LEN);
 121
 122        return tfm;
 123}
 124
 125
 126void ieee80211_aes_cmac_key_free(struct crypto_cipher *tfm)
 127{
 128        crypto_free_cipher(tfm);
 129}
 130
 131void ieee80211_aes_cmac_calculate_k1_k2(struct ieee80211_key_conf *keyconf,
 132                                        u8 *k1, u8 *k2)
 133{
 134        u8 l[AES_BLOCK_SIZE] = {};
 135        struct ieee80211_key *key =
 136                container_of(keyconf, struct ieee80211_key, conf);
 137
 138        crypto_cipher_encrypt_one(key->u.aes_cmac.tfm, l, l);
 139
 140        memcpy(k1, l, AES_BLOCK_SIZE);
 141        gf_mulx(k1);
 142
 143        memcpy(k2, k1, AES_BLOCK_SIZE);
 144        gf_mulx(k2);
 145}
 146EXPORT_SYMBOL(ieee80211_aes_cmac_calculate_k1_k2);
 147