linux-12-af_alg-crypto-authenc-use-memcpy_sglist-instead-of-null-skcipher.patch

Subject: [PATCH 6.12 5/8] crypto: authenc - use memcpy_sglist() instead of null skcipher
Date: Wed, 29 Apr 2026 23:06:59 -0700
Message-ID: <20260430060702.110091-6-ebiggers@kernel.org>
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From: Eric Biggers <ebiggers@google.com>

commit dbc4b1458e931e47198c3165ff5853bc1ad6bd7a upstream.

For copying data between two scatterlists, just use memcpy_sglist()
instead of the so-called "null skcipher".  This is much simpler.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---
 crypto/Kconfig      |  1 -
 crypto/authenc.c    | 32 +-------------------------------
 crypto/authencesn.c | 38 +++-----------------------------------
 3 files changed, 4 insertions(+), 67 deletions(-)

diff --git a/crypto/Kconfig b/crypto/Kconfig
index c2d0622d99b8..a997e97937e0 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -220,11 +220,10 @@ config CRYPTO_AUTHENC
 	tristate "Authenc support"
 	select CRYPTO_AEAD
 	select CRYPTO_SKCIPHER
 	select CRYPTO_MANAGER
 	select CRYPTO_HASH
-	select CRYPTO_NULL
 	help
 	  Authenc: Combined mode wrapper for IPsec.
 
 	  This is required for IPSec ESP (XFRM_ESP).
 
diff --git a/crypto/authenc.c b/crypto/authenc.c
index d04068af9833..f1f7886bb34c 100644
--- a/crypto/authenc.c
+++ b/crypto/authenc.c
@@ -7,11 +7,10 @@
 
 #include <crypto/internal/aead.h>
 #include <crypto/internal/hash.h>
 #include <crypto/internal/skcipher.h>
 #include <crypto/authenc.h>
-#include <crypto/null.h>
 #include <crypto/scatterwalk.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -26,11 +25,10 @@ struct authenc_instance_ctx {
 };
 
 struct crypto_authenc_ctx {
 	struct crypto_ahash *auth;
 	struct crypto_skcipher *enc;
-	struct crypto_sync_skcipher *null;
 };
 
 struct authenc_request_ctx {
 	struct scatterlist src[2];
 	struct scatterlist dst[2];
@@ -184,25 +182,10 @@ static void crypto_authenc_encrypt_done(void *data, int err)
 	}
 	err = crypto_authenc_genicv(areq, CRYPTO_TFM_REQ_MAY_SLEEP);
 	authenc_request_complete(areq, err);
 }
 
-static int crypto_authenc_copy_assoc(struct aead_request *req)
-{
-	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
-	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
-	SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
-
-	skcipher_request_set_sync_tfm(skreq, ctx->null);
-	skcipher_request_set_callback(skreq, aead_request_flags(req),
-				      NULL, NULL);
-	skcipher_request_set_crypt(skreq, req->src, req->dst, req->assoclen,
-				   NULL);
-
-	return crypto_skcipher_encrypt(skreq);
-}
-
 static int crypto_authenc_encrypt(struct aead_request *req)
 {
 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
 	struct aead_instance *inst = aead_alg_instance(authenc);
 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
@@ -217,14 +200,11 @@ static int crypto_authenc_encrypt(struct aead_request *req)
 
 	src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
 	dst = src;
 
 	if (req->src != req->dst) {
-		err = crypto_authenc_copy_assoc(req);
-		if (err)
-			return err;
-
+		memcpy_sglist(req->dst, req->src, req->assoclen);
 		dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
 	}
 
 	skcipher_request_set_tfm(skreq, enc);
 	skcipher_request_set_callback(skreq, aead_request_flags(req),
@@ -326,11 +306,10 @@ static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
 	struct aead_instance *inst = aead_alg_instance(tfm);
 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 	struct crypto_ahash *auth;
 	struct crypto_skcipher *enc;
-	struct crypto_sync_skcipher *null;
 	int err;
 
 	auth = crypto_spawn_ahash(&ictx->auth);
 	if (IS_ERR(auth))
 		return PTR_ERR(auth);
@@ -338,18 +317,12 @@ static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
 	enc = crypto_spawn_skcipher(&ictx->enc);
 	err = PTR_ERR(enc);
 	if (IS_ERR(enc))
 		goto err_free_ahash;
 
-	null = crypto_get_default_null_skcipher();
-	err = PTR_ERR(null);
-	if (IS_ERR(null))
-		goto err_free_skcipher;
-
 	ctx->auth = auth;
 	ctx->enc = enc;
-	ctx->null = null;
 
 	crypto_aead_set_reqsize(
 		tfm,
 		sizeof(struct authenc_request_ctx) +
 		ictx->reqoff +
@@ -359,12 +332,10 @@ static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
 		      sizeof(struct skcipher_request) +
 		      crypto_skcipher_reqsize(enc)));
 
 	return 0;
 
-err_free_skcipher:
-	crypto_free_skcipher(enc);
 err_free_ahash:
 	crypto_free_ahash(auth);
 	return err;
 }
 
@@ -372,11 +343,10 @@ static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)
 {
 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
 
 	crypto_free_ahash(ctx->auth);
 	crypto_free_skcipher(ctx->enc);
-	crypto_put_default_null_skcipher();
 }
 
 static void crypto_authenc_free(struct aead_instance *inst)
 {
 	struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);
diff --git a/crypto/authencesn.c b/crypto/authencesn.c
index e08032e80f18..a5fbb638d9d7 100644
--- a/crypto/authencesn.c
+++ b/crypto/authencesn.c
@@ -10,11 +10,10 @@
 
 #include <crypto/internal/aead.h>
 #include <crypto/internal/hash.h>
 #include <crypto/internal/skcipher.h>
 #include <crypto/authenc.h>
-#include <crypto/null.h>
 #include <crypto/scatterwalk.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -29,11 +28,10 @@ struct authenc_esn_instance_ctx {
 
 struct crypto_authenc_esn_ctx {
 	unsigned int reqoff;
 	struct crypto_ahash *auth;
 	struct crypto_skcipher *enc;
-	struct crypto_sync_skcipher *null;
 };
 
 struct authenc_esn_request_ctx {
 	struct scatterlist src[2];
 	struct scatterlist dst[2];
@@ -156,24 +154,10 @@ static void crypto_authenc_esn_encrypt_done(void *data, int err)
 		err = crypto_authenc_esn_genicv(areq, 0);
 
 	authenc_esn_request_complete(areq, err);
 }
 
-static int crypto_authenc_esn_copy(struct aead_request *req, unsigned int len)
-{
-	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
-	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
-	SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
-
-	skcipher_request_set_sync_tfm(skreq, ctx->null);
-	skcipher_request_set_callback(skreq, aead_request_flags(req),
-				      NULL, NULL);
-	skcipher_request_set_crypt(skreq, req->src, req->dst, len, NULL);
-
-	return crypto_skcipher_encrypt(skreq);
-}
-
 static int crypto_authenc_esn_encrypt(struct aead_request *req)
 {
 	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
 	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
 	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
@@ -191,14 +175,11 @@ static int crypto_authenc_esn_encrypt(struct aead_request *req)
 	sg_init_table(areq_ctx->src, 2);
 	src = scatterwalk_ffwd(areq_ctx->src, req->src, assoclen);
 	dst = src;
 
 	if (req->src != req->dst) {
-		err = crypto_authenc_esn_copy(req, assoclen);
-		if (err)
-			return err;
-
+		memcpy_sglist(req->dst, req->src, assoclen);
 		sg_init_table(areq_ctx->dst, 2);
 		dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, assoclen);
 	}
 
 	skcipher_request_set_tfm(skreq, enc);
@@ -281,15 +262,12 @@ static int crypto_authenc_esn_decrypt(struct aead_request *req)
 	if (assoclen < 8)
 		return -EINVAL;
 
 	cryptlen -= authsize;
 
-	if (req->src != dst) {
-		err = crypto_authenc_esn_copy(req, assoclen + cryptlen);
-		if (err)
-			return err;
-	}
+	if (req->src != dst)
+		memcpy_sglist(dst, req->src, assoclen + cryptlen);
 
 	scatterwalk_map_and_copy(ihash, req->src, assoclen + cryptlen,
 				 authsize, 0);
 
 	if (!authsize)
@@ -321,11 +299,10 @@ static int crypto_authenc_esn_init_tfm(struct crypto_aead *tfm)
 	struct aead_instance *inst = aead_alg_instance(tfm);
 	struct authenc_esn_instance_ctx *ictx = aead_instance_ctx(inst);
 	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
 	struct crypto_ahash *auth;
 	struct crypto_skcipher *enc;
-	struct crypto_sync_skcipher *null;
 	int err;
 
 	auth = crypto_spawn_ahash(&ictx->auth);
 	if (IS_ERR(auth))
 		return PTR_ERR(auth);
@@ -333,18 +310,12 @@ static int crypto_authenc_esn_init_tfm(struct crypto_aead *tfm)
 	enc = crypto_spawn_skcipher(&ictx->enc);
 	err = PTR_ERR(enc);
 	if (IS_ERR(enc))
 		goto err_free_ahash;
 
-	null = crypto_get_default_null_skcipher();
-	err = PTR_ERR(null);
-	if (IS_ERR(null))
-		goto err_free_skcipher;
-
 	ctx->auth = auth;
 	ctx->enc = enc;
-	ctx->null = null;
 
 	ctx->reqoff = 2 * crypto_ahash_digestsize(auth);
 
 	crypto_aead_set_reqsize(
 		tfm,
@@ -356,12 +327,10 @@ static int crypto_authenc_esn_init_tfm(struct crypto_aead *tfm)
 		      sizeof(struct skcipher_request) +
 		      crypto_skcipher_reqsize(enc)));
 
 	return 0;
 
-err_free_skcipher:
-	crypto_free_skcipher(enc);
 err_free_ahash:
 	crypto_free_ahash(auth);
 	return err;
 }
 
@@ -369,11 +338,10 @@ static void crypto_authenc_esn_exit_tfm(struct crypto_aead *tfm)
 {
 	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
 
 	crypto_free_ahash(ctx->auth);
 	crypto_free_skcipher(ctx->enc);
-	crypto_put_default_null_skcipher();
 }
 
 static void crypto_authenc_esn_free(struct aead_instance *inst)
 {
 	struct authenc_esn_instance_ctx *ctx = aead_instance_ctx(inst);
-- 
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