crypto: skcipher - Add skcipher_ialg_simple helper

This patch introduces the skcipher_ialg_simple helper which fetches
the crypto_alg structure from a simple skcipher instance's spawn.

This allows us to remove the third argument from the function
skcipher_alloc_instance_simple.

In doing so the reference count to the algorithm is now maintained
by the Crypto API and the caller no longer needs to drop the alg
refcount.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/cbc.c

@@ -54,10 +54,12 @@ static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 	struct crypto_alg *alg;
 	int err;
 
-	inst = skcipher_alloc_instance_simple(tmpl, tb, &alg);
+	inst = skcipher_alloc_instance_simple(tmpl, tb);
 	if (IS_ERR(inst))
 		return PTR_ERR(inst);
 
+	alg = skcipher_ialg_simple(inst);
+
 	err = -EINVAL;
 	if (!is_power_of_2(alg->cra_blocksize))
 		goto out_free_inst;
@@ -66,14 +68,11 @@ static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 	inst->alg.decrypt = crypto_cbc_decrypt;
 
 	err = skcipher_register_instance(tmpl, inst);
-	if (err)
-		goto out_free_inst;
-	goto out_put_alg;
-
+	if (err) {
 out_free_inst:
-	inst->free(inst);
-out_put_alg:
-	crypto_mod_put(alg);
+		inst->free(inst);
+	}
+
 	return err;
 }
 

crypto/cfb.c

@@ -203,10 +203,12 @@ static int crypto_cfb_create(struct crypto_template *tmpl, struct rtattr **tb)
 	struct crypto_alg *alg;
 	int err;
 
-	inst = skcipher_alloc_instance_simple(tmpl, tb, &alg);
+	inst = skcipher_alloc_instance_simple(tmpl, tb);
 	if (IS_ERR(inst))
 		return PTR_ERR(inst);
 
+	alg = skcipher_ialg_simple(inst);
+
 	/* CFB mode is a stream cipher. */
 	inst->alg.base.cra_blocksize = 1;
 
@@ -223,7 +225,6 @@ static int crypto_cfb_create(struct crypto_template *tmpl, struct rtattr **tb)
 	if (err)
 		inst->free(inst);
 
-	crypto_mod_put(alg);
 	return err;
 }
 

crypto/ctr.c

@@ -129,10 +129,12 @@ static int crypto_ctr_create(struct crypto_template *tmpl, struct rtattr **tb)
 	struct crypto_alg *alg;
 	int err;
 
-	inst = skcipher_alloc_instance_simple(tmpl, tb, &alg);
+	inst = skcipher_alloc_instance_simple(tmpl, tb);
 	if (IS_ERR(inst))
 		return PTR_ERR(inst);
 
+	alg = skcipher_ialg_simple(inst);
+
 	/* Block size must be >= 4 bytes. */
 	err = -EINVAL;
 	if (alg->cra_blocksize < 4)
@@ -155,14 +157,11 @@ static int crypto_ctr_create(struct crypto_template *tmpl, struct rtattr **tb)
 	inst->alg.decrypt = crypto_ctr_crypt;
 
 	err = skcipher_register_instance(tmpl, inst);
-	if (err)
-		goto out_free_inst;
-	goto out_put_alg;
-
+	if (err) {
 out_free_inst:
-	inst->free(inst);
-out_put_alg:
-	crypto_mod_put(alg);
+		inst->free(inst);
+	}
+
 	return err;
 }
 

crypto/ecb.c

@@ -61,10 +61,9 @@ static int crypto_ecb_decrypt(struct skcipher_request *req)
 static int crypto_ecb_create(struct crypto_template *tmpl, struct rtattr **tb)
 {
 	struct skcipher_instance *inst;
-	struct crypto_alg *alg;
 	int err;
 
-	inst = skcipher_alloc_instance_simple(tmpl, tb, &alg);
+	inst = skcipher_alloc_instance_simple(tmpl, tb);
 	if (IS_ERR(inst))
 		return PTR_ERR(inst);
 
@@ -76,7 +75,7 @@ static int crypto_ecb_create(struct crypto_template *tmpl, struct rtattr **tb)
 	err = skcipher_register_instance(tmpl, inst);
 	if (err)
 		inst->free(inst);
-	crypto_mod_put(alg);
+
 	return err;
 }
 

crypto/keywrap.c

@@ -266,10 +266,12 @@ static int crypto_kw_create(struct crypto_template *tmpl, struct rtattr **tb)
 	struct crypto_alg *alg;
 	int err;
 
-	inst = skcipher_alloc_instance_simple(tmpl, tb, &alg);
+	inst = skcipher_alloc_instance_simple(tmpl, tb);
 	if (IS_ERR(inst))
 		return PTR_ERR(inst);
 
+	alg = skcipher_ialg_simple(inst);
+
 	err = -EINVAL;
 	/* Section 5.1 requirement for KW */
 	if (alg->cra_blocksize != sizeof(struct crypto_kw_block))
@@ -283,14 +285,11 @@ static int crypto_kw_create(struct crypto_template *tmpl, struct rtattr **tb)
 	inst->alg.decrypt = crypto_kw_decrypt;
 
 	err = skcipher_register_instance(tmpl, inst);
-	if (err)
-		goto out_free_inst;
-	goto out_put_alg;
-
+	if (err) {
 out_free_inst:
-	inst->free(inst);
-out_put_alg:
-	crypto_mod_put(alg);
+		inst->free(inst);
+	}
+
 	return err;
 }
 

crypto/ofb.c

@@ -55,10 +55,12 @@ static int crypto_ofb_create(struct crypto_template *tmpl, struct rtattr **tb)
 	struct crypto_alg *alg;
 	int err;
 
-	inst = skcipher_alloc_instance_simple(tmpl, tb, &alg);
+	inst = skcipher_alloc_instance_simple(tmpl, tb);
 	if (IS_ERR(inst))
 		return PTR_ERR(inst);
 
+	alg = skcipher_ialg_simple(inst);
+
 	/* OFB mode is a stream cipher. */
 	inst->alg.base.cra_blocksize = 1;
 
@@ -75,7 +77,6 @@ static int crypto_ofb_create(struct crypto_template *tmpl, struct rtattr **tb)
 	if (err)
 		inst->free(inst);
 
-	crypto_mod_put(alg);
 	return err;
 }
 

crypto/pcbc.c

@@ -153,10 +153,9 @@ static int crypto_pcbc_decrypt(struct skcipher_request *req)
 static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 {
 	struct skcipher_instance *inst;
-	struct crypto_alg *alg;
 	int err;
 
-	inst = skcipher_alloc_instance_simple(tmpl, tb, &alg);
+	inst = skcipher_alloc_instance_simple(tmpl, tb);
 	if (IS_ERR(inst))
 		return PTR_ERR(inst);
 
@@ -166,7 +165,7 @@ static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 	err = skcipher_register_instance(tmpl, inst);
 	if (err)
 		inst->free(inst);
-	crypto_mod_put(alg);
+
 	return err;
 }
 

crypto/skcipher.c

@@ -938,15 +938,12 @@ static void skcipher_free_instance_simple(struct skcipher_instance *inst)
  *
  * @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 skcipher_instance *skcipher_alloc_instance_simple(
+	struct crypto_template *tmpl, struct rtattr **tb)
 {
 	struct crypto_attr_type *algt;
 	struct crypto_alg *cipher_alg;
@@ -982,6 +979,7 @@ skcipher_alloc_instance_simple(struct crypto_template *tmpl, struct rtattr **tb,
 	if (err)
 		goto err_free_inst;
 
+	spawn->dropref = true;
 	err = crypto_init_spawn(spawn, cipher_alg,
 				skcipher_crypto_instance(inst),
 				CRYPTO_ALG_TYPE_MASK);
@@ -1003,7 +1001,6 @@ skcipher_alloc_instance_simple(struct crypto_template *tmpl, struct rtattr **tb,
 	inst->alg.init = skcipher_init_tfm_simple;
 	inst->alg.exit = skcipher_exit_tfm_simple;
 
-	*cipher_alg_ret = cipher_alg;
 	return inst;
 
 err_free_inst:

include/crypto/internal/skcipher.h

@@ -214,9 +214,17 @@ skcipher_cipher_simple(struct crypto_skcipher *tfm)
 
 	return ctx->cipher;
 }
-struct skcipher_instance *
-skcipher_alloc_instance_simple(struct crypto_template *tmpl, struct rtattr **tb,
-			       struct crypto_alg **cipher_alg_ret);
+
+struct skcipher_instance *skcipher_alloc_instance_simple(
+	struct crypto_template *tmpl, struct rtattr **tb);
+
+static inline struct crypto_alg *skcipher_ialg_simple(
+	struct skcipher_instance *inst)
+{
+	struct crypto_spawn *spawn = skcipher_instance_ctx(inst);
+
+	return spawn->alg;
+}
 
 #endif	/* _CRYPTO_INTERNAL_SKCIPHER_H */