// SPDX-License-Identifier: GPL-2.0-or-later/* * CMAC: Cipher Block Mode for Authentication * * Copyright © 2013 Jussi Kivilinna <jussi.kivilinna@iki.fi> * * Based on work by: *  Copyright © 2013 Tom St Denis <tstdenis@elliptictech.com> * Based on crypto/xcbc.c: *  Copyright © 2006 USAGI/WIDE Project, *   Author: Kazunori Miyazawa <miyazawa@linux-ipv6.org> */ #include <crypto/internal/cipher.h>#include <crypto/internal/hash.h>#include <crypto/utils.h>#include <linux/err.h>#include <linux/kernel.h>#include <linux/module.h>#include <linux/slab.h>#include <linux/string.h> /* * +------------------------ * | <parent tfm> * +------------------------ * | cmac_tfm_ctx * +------------------------ * | consts (block size * 2) * +------------------------ */struct cmac_tfm_ctx {	struct crypto_cipher *child;	__be64 consts[];}; static int crypto_cmac_digest_setkey(struct crypto_shash *parent,				     const u8 *inkey, unsigned int keylen){	struct cmac_tfm_ctx *ctx = crypto_shash_ctx(parent);	unsigned int bs = crypto_shash_blocksize(parent);	__be64 *consts = ctx->consts;	u64 _const[2];	int i, err = 0;	u8 msb_mask, gfmask; 	err = crypto_cipher_setkey(ctx->child, inkey, keylen);	if (err)		return err; 	/* encrypt the zero block */	memset(consts, 0, bs);	crypto_cipher_encrypt_one(ctx->child, (u8 *)consts, (u8 *)consts); 	switch (bs) {	case 16:		gfmask = 0x87;		_const[0] = be64_to_cpu(consts[1]);		_const[1] = be64_to_cpu(consts[0]); 		/* gf(2^128) multiply zero-ciphertext with u and u^2 */		for (i = 0; i < 4; i += 2) {			msb_mask = ((s64)_const[1] >> 63) & gfmask;			_const[1] = (_const[1] << 1) | (_const[0] >> 63);			_const[0] = (_const[0] << 1) ^ msb_mask; 			consts[i + 0] = cpu_to_be64(_const[1]);			consts[i + 1] = cpu_to_be64(_const[0]);		} 		break;	case 8:		gfmask = 0x1B;		_const[0] = be64_to_cpu(consts[0]); 		/* gf(2^64) multiply zero-ciphertext with u and u^2 */		for (i = 0; i < 2; i++) {			msb_mask = ((s64)_const[0] >> 63) & gfmask;			_const[0] = (_const[0] << 1) ^ msb_mask; 			consts[i] = cpu_to_be64(_const[0]);		} 		break;	} 	return 0;} static int crypto_cmac_digest_init(struct shash_desc *pdesc){	int bs = crypto_shash_blocksize(pdesc->tfm);	u8 *prev = shash_desc_ctx(pdesc); 	memset(prev, 0, bs);	return 0;} static int crypto_cmac_digest_update(struct shash_desc *pdesc, const u8 *p,				     unsigned int len){	struct crypto_shash *parent = pdesc->tfm;	struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);	struct crypto_cipher *tfm = tctx->child;	int bs = crypto_shash_blocksize(parent);	u8 *prev = shash_desc_ctx(pdesc); 	do {		crypto_xor(prev, p, bs);		crypto_cipher_encrypt_one(tfm, prev, prev);		p += bs;		len -= bs;	} while (len >= bs);	return len;} static int crypto_cmac_digest_finup(struct shash_desc *pdesc, const u8 *src,				    unsigned int len, u8 *out){	struct crypto_shash *parent = pdesc->tfm;	struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);	struct crypto_cipher *tfm = tctx->child;	int bs = crypto_shash_blocksize(parent);	u8 *prev = shash_desc_ctx(pdesc);	unsigned int offset = 0; 	crypto_xor(prev, src, len);	if (len != bs) {		prev[len] ^= 0x80;		offset += bs;	}	crypto_xor(prev, (const u8 *)tctx->consts + offset, bs);	crypto_cipher_encrypt_one(tfm, out, prev);	return 0;} static int cmac_init_tfm(struct crypto_shash *tfm){	struct shash_instance *inst = shash_alg_instance(tfm);	struct cmac_tfm_ctx *ctx = crypto_shash_ctx(tfm);	struct crypto_cipher_spawn *spawn;	struct crypto_cipher *cipher; 	spawn = shash_instance_ctx(inst);	cipher = crypto_spawn_cipher(spawn);	if (IS_ERR(cipher))		return PTR_ERR(cipher); 	ctx->child = cipher; 	return 0;} static void cmac_exit_tfm(struct crypto_shash *tfm){	struct cmac_tfm_ctx *ctx = crypto_shash_ctx(tfm);	crypto_free_cipher(ctx->child);} static int cmac_create(struct crypto_template *tmpl, struct rtattr **tb){	struct shash_instance *inst;	struct crypto_cipher_spawn *spawn;	struct crypto_alg *alg;	u32 mask;	int err; 	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask);	if (err)		return err; 	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);	if (!inst)		return -ENOMEM;	spawn = shash_instance_ctx(inst); 	err = crypto_grab_cipher(spawn, shash_crypto_instance(inst),				 crypto_attr_alg_name(tb[1]), 0, mask);	if (err)		goto err_free_inst;	alg = crypto_spawn_cipher_alg(spawn); 	switch (alg->cra_blocksize) {	case 16:	case 8:		break;	default:		err = -EINVAL;		goto err_free_inst;	} 	err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);	if (err)		goto err_free_inst; 	inst->alg.base.cra_priority = alg->cra_priority;	inst->alg.base.cra_blocksize = alg->cra_blocksize;	inst->alg.base.cra_ctxsize = sizeof(struct cmac_tfm_ctx) +				     alg->cra_blocksize * 2;	inst->alg.base.cra_flags = CRYPTO_AHASH_ALG_BLOCK_ONLY |				   CRYPTO_AHASH_ALG_FINAL_NONZERO; 	inst->alg.digestsize = alg->cra_blocksize;	inst->alg.descsize = alg->cra_blocksize;	inst->alg.init = crypto_cmac_digest_init;	inst->alg.update = crypto_cmac_digest_update;	inst->alg.finup = crypto_cmac_digest_finup;	inst->alg.setkey = crypto_cmac_digest_setkey;	inst->alg.init_tfm = cmac_init_tfm;	inst->alg.exit_tfm = cmac_exit_tfm; 	inst->free = shash_free_singlespawn_instance; 	err = shash_register_instance(tmpl, inst);	if (err) {err_free_inst:		shash_free_singlespawn_instance(inst);	}	return err;} static struct crypto_template crypto_cmac_tmpl = {	.name = "cmac",	.create = cmac_create,	.module = THIS_MODULE,}; static int __init crypto_cmac_module_init(void){	return crypto_register_template(&crypto_cmac_tmpl);} static void __exit crypto_cmac_module_exit(void){	crypto_unregister_template(&crypto_cmac_tmpl);} module_init(crypto_cmac_module_init);module_exit(crypto_cmac_module_exit); MODULE_LICENSE("GPL");MODULE_DESCRIPTION("CMAC keyed hash algorithm");MODULE_ALIAS_CRYPTO("cmac");MODULE_IMPORT_NS("CRYPTO_INTERNAL");