crypto: add CMAC support to CryptoAPI
Patch adds support for NIST recommended block cipher mode CMAC to CryptoAPI. This work is based on Tom St Denis' earlier patch, http://marc.info/?l=linux-crypto-vger&m=135877306305466&w=2 Cc: Tom St Denis <tstdenis@elliptictech.com> Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Jussi Kivilinna
committed by
Herbert Xu
Herbert Xu
parent
e448370d73
commit
93b5e86a6d
315
crypto/cmac.c
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315
crypto/cmac.c
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/*
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* CMAC: Cipher Block Mode for Authentication
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*
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* Copyright © 2013 Jussi Kivilinna <jussi.kivilinna@iki.fi>
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*
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* Based on work by:
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* Copyright © 2013 Tom St Denis <tstdenis@elliptictech.com>
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* Based on crypto/xcbc.c:
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* Copyright © 2006 USAGI/WIDE Project,
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* Author: Kazunori Miyazawa <miyazawa@linux-ipv6.org>
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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 as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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*/
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#include <crypto/internal/hash.h>
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#include <linux/err.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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/*
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* +------------------------
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* | <parent tfm>
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* +------------------------
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* | cmac_tfm_ctx
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* +------------------------
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* | consts (block size * 2)
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* +------------------------
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*/
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struct cmac_tfm_ctx {
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struct crypto_cipher *child;
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u8 ctx[];
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};
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/*
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* +------------------------
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* | <shash desc>
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* +------------------------
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* | cmac_desc_ctx
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* +------------------------
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* | odds (block size)
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* +------------------------
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* | prev (block size)
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* +------------------------
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*/
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struct cmac_desc_ctx {
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unsigned int len;
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u8 ctx[];
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};
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static int crypto_cmac_digest_setkey(struct crypto_shash *parent,
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const u8 *inkey, unsigned int keylen)
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{
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unsigned long alignmask = crypto_shash_alignmask(parent);
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struct cmac_tfm_ctx *ctx = crypto_shash_ctx(parent);
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unsigned int bs = crypto_shash_blocksize(parent);
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__be64 *consts = PTR_ALIGN((void *)ctx->ctx, alignmask + 1);
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u64 _const[2];
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int i, err = 0;
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u8 msb_mask, gfmask;
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err = crypto_cipher_setkey(ctx->child, inkey, keylen);
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if (err)
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return err;
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/* encrypt the zero block */
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memset(consts, 0, bs);
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crypto_cipher_encrypt_one(ctx->child, (u8 *)consts, (u8 *)consts);
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switch (bs) {
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case 16:
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gfmask = 0x87;
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_const[0] = be64_to_cpu(consts[1]);
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_const[1] = be64_to_cpu(consts[0]);
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/* gf(2^128) multiply zero-ciphertext with u and u^2 */
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for (i = 0; i < 4; i += 2) {
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msb_mask = ((s64)_const[1] >> 63) & gfmask;
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_const[1] = (_const[1] << 1) | (_const[0] >> 63);
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_const[0] = (_const[0] << 1) ^ msb_mask;
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consts[i + 0] = cpu_to_be64(_const[1]);
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consts[i + 1] = cpu_to_be64(_const[0]);
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}
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break;
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case 8:
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gfmask = 0x1B;
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_const[0] = be64_to_cpu(consts[0]);
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/* gf(2^64) multiply zero-ciphertext with u and u^2 */
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for (i = 0; i < 2; i++) {
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msb_mask = ((s64)_const[0] >> 63) & gfmask;
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_const[0] = (_const[0] << 1) ^ msb_mask;
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consts[i] = cpu_to_be64(_const[0]);
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}
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break;
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}
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return 0;
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}
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static int crypto_cmac_digest_init(struct shash_desc *pdesc)
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{
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unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm);
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struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
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int bs = crypto_shash_blocksize(pdesc->tfm);
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u8 *prev = PTR_ALIGN((void *)ctx->ctx, alignmask + 1) + bs;
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ctx->len = 0;
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memset(prev, 0, bs);
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return 0;
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}
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static int crypto_cmac_digest_update(struct shash_desc *pdesc, const u8 *p,
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unsigned int len)
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{
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struct crypto_shash *parent = pdesc->tfm;
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unsigned long alignmask = crypto_shash_alignmask(parent);
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struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
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struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
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struct crypto_cipher *tfm = tctx->child;
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int bs = crypto_shash_blocksize(parent);
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u8 *odds = PTR_ALIGN((void *)ctx->ctx, alignmask + 1);
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u8 *prev = odds + bs;
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/* checking the data can fill the block */
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if ((ctx->len + len) <= bs) {
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memcpy(odds + ctx->len, p, len);
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ctx->len += len;
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return 0;
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}
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/* filling odds with new data and encrypting it */
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memcpy(odds + ctx->len, p, bs - ctx->len);
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len -= bs - ctx->len;
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p += bs - ctx->len;
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crypto_xor(prev, odds, bs);
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crypto_cipher_encrypt_one(tfm, prev, prev);
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/* clearing the length */
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ctx->len = 0;
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/* encrypting the rest of data */
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while (len > bs) {
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crypto_xor(prev, p, bs);
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crypto_cipher_encrypt_one(tfm, prev, prev);
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p += bs;
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len -= bs;
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}
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/* keeping the surplus of blocksize */
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if (len) {
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memcpy(odds, p, len);
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ctx->len = len;
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}
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return 0;
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}
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static int crypto_cmac_digest_final(struct shash_desc *pdesc, u8 *out)
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{
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struct crypto_shash *parent = pdesc->tfm;
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unsigned long alignmask = crypto_shash_alignmask(parent);
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struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
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struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
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struct crypto_cipher *tfm = tctx->child;
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int bs = crypto_shash_blocksize(parent);
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u8 *consts = PTR_ALIGN((void *)tctx->ctx, alignmask + 1);
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u8 *odds = PTR_ALIGN((void *)ctx->ctx, alignmask + 1);
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u8 *prev = odds + bs;
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unsigned int offset = 0;
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if (ctx->len != bs) {
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unsigned int rlen;
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u8 *p = odds + ctx->len;
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*p = 0x80;
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p++;
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rlen = bs - ctx->len - 1;
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if (rlen)
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memset(p, 0, rlen);
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offset += bs;
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}
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crypto_xor(prev, odds, bs);
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crypto_xor(prev, consts + offset, bs);
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crypto_cipher_encrypt_one(tfm, out, prev);
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return 0;
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}
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static int cmac_init_tfm(struct crypto_tfm *tfm)
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{
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struct crypto_cipher *cipher;
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struct crypto_instance *inst = (void *)tfm->__crt_alg;
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struct crypto_spawn *spawn = crypto_instance_ctx(inst);
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struct cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
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cipher = crypto_spawn_cipher(spawn);
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if (IS_ERR(cipher))
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return PTR_ERR(cipher);
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ctx->child = cipher;
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return 0;
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};
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static void cmac_exit_tfm(struct crypto_tfm *tfm)
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{
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struct cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
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crypto_free_cipher(ctx->child);
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}
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static int cmac_create(struct crypto_template *tmpl, struct rtattr **tb)
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{
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struct shash_instance *inst;
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struct crypto_alg *alg;
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unsigned long alignmask;
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int err;
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err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
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if (err)
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return err;
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alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
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CRYPTO_ALG_TYPE_MASK);
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if (IS_ERR(alg))
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return PTR_ERR(alg);
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switch (alg->cra_blocksize) {
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case 16:
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case 8:
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break;
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default:
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goto out_put_alg;
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}
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inst = shash_alloc_instance("cmac", alg);
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err = PTR_ERR(inst);
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if (IS_ERR(inst))
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goto out_put_alg;
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err = crypto_init_spawn(shash_instance_ctx(inst), alg,
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shash_crypto_instance(inst),
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CRYPTO_ALG_TYPE_MASK);
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if (err)
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goto out_free_inst;
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alignmask = alg->cra_alignmask | (sizeof(long) - 1);
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inst->alg.base.cra_alignmask = alignmask;
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inst->alg.base.cra_priority = alg->cra_priority;
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inst->alg.base.cra_blocksize = alg->cra_blocksize;
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inst->alg.digestsize = alg->cra_blocksize;
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inst->alg.descsize =
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ALIGN(sizeof(struct cmac_desc_ctx), crypto_tfm_ctx_alignment())
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+ (alignmask & ~(crypto_tfm_ctx_alignment() - 1))
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+ alg->cra_blocksize * 2;
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inst->alg.base.cra_ctxsize =
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ALIGN(sizeof(struct cmac_tfm_ctx), alignmask + 1)
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+ alg->cra_blocksize * 2;
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inst->alg.base.cra_init = cmac_init_tfm;
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inst->alg.base.cra_exit = cmac_exit_tfm;
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inst->alg.init = crypto_cmac_digest_init;
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inst->alg.update = crypto_cmac_digest_update;
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inst->alg.final = crypto_cmac_digest_final;
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inst->alg.setkey = crypto_cmac_digest_setkey;
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err = shash_register_instance(tmpl, inst);
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if (err) {
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out_free_inst:
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shash_free_instance(shash_crypto_instance(inst));
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}
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out_put_alg:
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crypto_mod_put(alg);
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return err;
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}
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static struct crypto_template crypto_cmac_tmpl = {
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.name = "cmac",
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.create = cmac_create,
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.free = shash_free_instance,
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.module = THIS_MODULE,
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};
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static int __init crypto_cmac_module_init(void)
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{
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return crypto_register_template(&crypto_cmac_tmpl);
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}
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static void __exit crypto_cmac_module_exit(void)
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{
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crypto_unregister_template(&crypto_cmac_tmpl);
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}
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module_init(crypto_cmac_module_init);
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module_exit(crypto_cmac_module_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("CMAC keyed hash algorithm");
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