Commit 0872da16 authored by Eric Biggers's avatar Eric Biggers Committed by Herbert Xu
Browse files

crypto: skcipher - add helper for simple block cipher modes 



The majority of skcipher templates (including both the existing ones and
the ones remaining to be converted from the "blkcipher" API) just wrap a
single block cipher algorithm.  This includes cbc, cfb, ctr, ecb, kw,
ofb, and pcbc.  Add a helper function skcipher_alloc_instance_simple()
that handles allocating an skcipher instance for this common case.

Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Reviewed-by: default avatarStephan Mueller <smueller@chronox.de>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 251b7aea

crypto/skcipher.c

+131 −0
Original line number Diff line number Diff line
@@ -1058,5 +1058,136 @@ int skcipher_register_instance(struct crypto_template *tmpl, 
}

EXPORT_SYMBOL_GPL(skcipher_register_instance);



static int skcipher_setkey_simple(struct crypto_skcipher *tfm, const u8 *key,

				  unsigned int keylen)

{

	struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);

	int err;



	crypto_cipher_clear_flags(cipher, CRYPTO_TFM_REQ_MASK);

	crypto_cipher_set_flags(cipher, crypto_skcipher_get_flags(tfm) &

				CRYPTO_TFM_REQ_MASK);

	err = crypto_cipher_setkey(cipher, key, keylen);

	crypto_skcipher_set_flags(tfm, crypto_cipher_get_flags(cipher) &

				  CRYPTO_TFM_RES_MASK);

	return err;

}



static int skcipher_init_tfm_simple(struct crypto_skcipher *tfm)

{

	struct skcipher_instance *inst = skcipher_alg_instance(tfm);

	struct crypto_spawn *spawn = skcipher_instance_ctx(inst);

	struct skcipher_ctx_simple *ctx = crypto_skcipher_ctx(tfm);

	struct crypto_cipher *cipher;



	cipher = crypto_spawn_cipher(spawn);

	if (IS_ERR(cipher))

		return PTR_ERR(cipher);



	ctx->cipher = cipher;

	return 0;

}



static void skcipher_exit_tfm_simple(struct crypto_skcipher *tfm)

{

	struct skcipher_ctx_simple *ctx = crypto_skcipher_ctx(tfm);



	crypto_free_cipher(ctx->cipher);

}



static void skcipher_free_instance_simple(struct skcipher_instance *inst)

{

	crypto_drop_spawn(skcipher_instance_ctx(inst));

	kfree(inst);

}



/**

 * skcipher_alloc_instance_simple - allocate instance of simple block cipher mode

 *

 * Allocate an skcipher_instance for a simple block cipher mode of operation,

 * e.g. cbc or ecb.  The instance context will have just a single crypto_spawn,

 * that for the underlying cipher.  The {min,max}_keysize, ivsize, blocksize,

 * alignmask, and priority are set from the underlying cipher but can be

 * overridden if needed.  The tfm context defaults to skcipher_ctx_simple, and

 * default ->setkey(), ->init(), and ->exit() methods are installed.

 *

 * @tmpl: the template being instantiated

 * @tb: the template parameters

 * @cipher_alg_ret: on success, a pointer to the underlying cipher algorithm is

 *		    returned here.  It must be dropped with crypto_mod_put().

 *

 * Return: a pointer to the new instance, or an ERR_PTR().  The caller still

 *	   needs to register the instance.

 */

struct skcipher_instance *

skcipher_alloc_instance_simple(struct crypto_template *tmpl, struct rtattr **tb,

			       struct crypto_alg **cipher_alg_ret)

{

	struct crypto_attr_type *algt;

	struct crypto_alg *cipher_alg;

	struct skcipher_instance *inst;

	struct crypto_spawn *spawn;

	u32 mask;

	int err;



	algt = crypto_get_attr_type(tb);

	if (IS_ERR(algt))

		return ERR_CAST(algt);



	if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)

		return ERR_PTR(-EINVAL);



	mask = CRYPTO_ALG_TYPE_MASK |

		crypto_requires_off(algt->type, algt->mask,

				    CRYPTO_ALG_NEED_FALLBACK);



	cipher_alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER, mask);

	if (IS_ERR(cipher_alg))

		return ERR_CAST(cipher_alg);



	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);

	if (!inst) {

		err = -ENOMEM;

		goto err_put_cipher_alg;

	}

	spawn = skcipher_instance_ctx(inst);



	err = crypto_inst_setname(skcipher_crypto_instance(inst), tmpl->name,

				  cipher_alg);

	if (err)

		goto err_free_inst;



	err = crypto_init_spawn(spawn, cipher_alg,

				skcipher_crypto_instance(inst),

				CRYPTO_ALG_TYPE_MASK);

	if (err)

		goto err_free_inst;

	inst->free = skcipher_free_instance_simple;



	/* Default algorithm properties, can be overridden */

	inst->alg.base.cra_blocksize = cipher_alg->cra_blocksize;

	inst->alg.base.cra_alignmask = cipher_alg->cra_alignmask;

	inst->alg.base.cra_priority = cipher_alg->cra_priority;

	inst->alg.min_keysize = cipher_alg->cra_cipher.cia_min_keysize;

	inst->alg.max_keysize = cipher_alg->cra_cipher.cia_max_keysize;

	inst->alg.ivsize = cipher_alg->cra_blocksize;



	/* Use skcipher_ctx_simple by default, can be overridden */

	inst->alg.base.cra_ctxsize = sizeof(struct skcipher_ctx_simple);

	inst->alg.setkey = skcipher_setkey_simple;

	inst->alg.init = skcipher_init_tfm_simple;

	inst->alg.exit = skcipher_exit_tfm_simple;



	*cipher_alg_ret = cipher_alg;

	return inst;



err_free_inst:

	kfree(inst);

err_put_cipher_alg:

	crypto_mod_put(cipher_alg);

	return ERR_PTR(err);

}

EXPORT_SYMBOL_GPL(skcipher_alloc_instance_simple);



MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("Symmetric key cipher type");

include/crypto/internal/skcipher.h

+15 −0
Original line number Diff line number Diff line
@@ -205,5 +205,20 @@ static inline unsigned int crypto_skcipher_alg_max_keysize( 
	return alg->max_keysize;

}



/* Helpers for simple block cipher modes of operation */

struct skcipher_ctx_simple {

	struct crypto_cipher *cipher;	/* underlying block cipher */

};

static inline struct crypto_cipher *

skcipher_cipher_simple(struct crypto_skcipher *tfm)

{

	struct skcipher_ctx_simple *ctx = crypto_skcipher_ctx(tfm);



	return ctx->cipher;

}

struct skcipher_instance *

skcipher_alloc_instance_simple(struct crypto_template *tmpl, struct rtattr **tb,

			       struct crypto_alg **cipher_alg_ret);



#endif	/* _CRYPTO_INTERNAL_SKCIPHER_H */

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