187 lines
3.6 KiB
C
187 lines
3.6 KiB
C
/*
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* Cryptographic API
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*
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* Michael MIC (IEEE 802.11i/TKIP) keyed digest
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*
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* Copyright (c) 2004 Jouni Malinen <j@w1.fi>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <crypto/internal/hash.h>
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#include <asm/byteorder.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/string.h>
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#include <linux/types.h>
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struct michael_mic_ctx {
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u32 l, r;
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};
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struct michael_mic_desc_ctx {
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u8 pending[4];
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size_t pending_len;
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u32 l, r;
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};
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static inline u32 xswap(u32 val)
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{
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return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8);
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}
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#define michael_block(l, r) \
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do { \
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r ^= rol32(l, 17); \
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l += r; \
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r ^= xswap(l); \
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l += r; \
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r ^= rol32(l, 3); \
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l += r; \
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r ^= ror32(l, 2); \
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l += r; \
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} while (0)
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static int michael_init(struct shash_desc *desc)
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{
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struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc);
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struct michael_mic_ctx *ctx = crypto_shash_ctx(desc->tfm);
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mctx->pending_len = 0;
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mctx->l = ctx->l;
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mctx->r = ctx->r;
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return 0;
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}
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static int michael_update(struct shash_desc *desc, const u8 *data,
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unsigned int len)
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{
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struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc);
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const __le32 *src;
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if (mctx->pending_len) {
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int flen = 4 - mctx->pending_len;
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if (flen > len)
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flen = len;
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memcpy(&mctx->pending[mctx->pending_len], data, flen);
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mctx->pending_len += flen;
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data += flen;
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len -= flen;
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if (mctx->pending_len < 4)
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return 0;
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src = (const __le32 *)mctx->pending;
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mctx->l ^= le32_to_cpup(src);
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michael_block(mctx->l, mctx->r);
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mctx->pending_len = 0;
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}
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src = (const __le32 *)data;
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while (len >= 4) {
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mctx->l ^= le32_to_cpup(src++);
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michael_block(mctx->l, mctx->r);
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len -= 4;
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}
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if (len > 0) {
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mctx->pending_len = len;
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memcpy(mctx->pending, src, len);
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}
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return 0;
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}
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static int michael_final(struct shash_desc *desc, u8 *out)
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{
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struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc);
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u8 *data = mctx->pending;
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__le32 *dst = (__le32 *)out;
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/* Last block and padding (0x5a, 4..7 x 0) */
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switch (mctx->pending_len) {
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case 0:
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mctx->l ^= 0x5a;
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break;
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case 1:
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mctx->l ^= data[0] | 0x5a00;
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break;
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case 2:
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mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000;
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break;
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case 3:
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mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) |
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0x5a000000;
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break;
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}
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michael_block(mctx->l, mctx->r);
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/* l ^= 0; */
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michael_block(mctx->l, mctx->r);
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dst[0] = cpu_to_le32(mctx->l);
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dst[1] = cpu_to_le32(mctx->r);
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return 0;
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}
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static int michael_setkey(struct crypto_shash *tfm, const u8 *key,
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unsigned int keylen)
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{
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struct michael_mic_ctx *mctx = crypto_shash_ctx(tfm);
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const __le32 *data = (const __le32 *)key;
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if (keylen != 8) {
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crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
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return -EINVAL;
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}
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mctx->l = le32_to_cpu(data[0]);
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mctx->r = le32_to_cpu(data[1]);
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return 0;
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}
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static struct shash_alg alg = {
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.digestsize = 8,
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.setkey = michael_setkey,
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.init = michael_init,
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.update = michael_update,
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.final = michael_final,
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.descsize = sizeof(struct michael_mic_desc_ctx),
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.base = {
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.cra_name = "michael_mic",
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.cra_blocksize = 8,
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.cra_alignmask = 3,
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.cra_ctxsize = sizeof(struct michael_mic_ctx),
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.cra_module = THIS_MODULE,
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}
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};
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static int __init michael_mic_init(void)
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{
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return crypto_register_shash(&alg);
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}
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static void __exit michael_mic_exit(void)
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{
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crypto_unregister_shash(&alg);
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}
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module_init(michael_mic_init);
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module_exit(michael_mic_exit);
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MODULE_LICENSE("GPL v2");
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MODULE_DESCRIPTION("Michael MIC");
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MODULE_AUTHOR("Jouni Malinen <j@w1.fi>");
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