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From: Ard Biesheuvel <ardb@kernel.org>
To: linux-crypto@vger.kernel.org
Cc: Eric Biggers <ebiggers@google.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Jamie Iles <jamie@jamieiles.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Rohit Maheshwari <rohitm@chelsio.com>,
	Fabio Estevam <festevam@gmail.com>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Vinay Kumar Yadav <vinay.yadav@chelsio.com>,
	Maxime Ripard <mripard@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Chen-Yu Tsai <wens@csie.org>,
	Corentin Labbe <clabbe.montjoie@gmail.com>,
	NXP Linux Team <linux-imx@nxp.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Ayush Sawal <ayush.sawal@chelsio.com>,
	linux-amlogic@lists.infradead.org, linux-omap@vger.kernel.org,
	Shawn Guo <shawnguo@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 11/12] crypto: qce - permit asynchronous skcipher as fallback
Date: Thu, 25 Jun 2020 14:42:52 +0200
Message-ID: <20200625124253.1906557-12-ardb@kernel.org> (raw)
In-Reply-To: <20200625124253.1906557-1-ardb@kernel.org>

Even though the qce driver implements asynchronous versions of ecb(aes),
cbc(aes)and xts(aes), the fallbacks it allocates are required to be
synchronous. Given that SIMD based software implementations are usually
asynchronous as well, even though they rarely complete asynchronously
(this typically only happens in cases where the request was made from
softirq context, while SIMD was already in use in the task context that
it interrupted), these implementations are disregarded, and either the
generic C version or another table based version implemented in assembler
is selected instead.

Since falling back to synchronous AES is not only a performance issue, but
potentially a security issue as well (due to the fact that table based AES
is not time invariant), let's fix this, by allocating an ordinary skcipher
as the fallback, and invoke it with the completion routine that was given
to the outer request.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 drivers/crypto/qce/cipher.h   |  3 ++-
 drivers/crypto/qce/skcipher.c | 27 ++++++++++----------
 2 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/drivers/crypto/qce/cipher.h b/drivers/crypto/qce/cipher.h
index 7770660bc853..cffa9fc628ff 100644
--- a/drivers/crypto/qce/cipher.h
+++ b/drivers/crypto/qce/cipher.h
@@ -14,7 +14,7 @@
 struct qce_cipher_ctx {
 	u8 enc_key[QCE_MAX_KEY_SIZE];
 	unsigned int enc_keylen;
-	struct crypto_sync_skcipher *fallback;
+	struct crypto_skcipher *fallback;
 };
 
 /**
@@ -43,6 +43,7 @@ struct qce_cipher_reqctx {
 	struct sg_table src_tbl;
 	struct scatterlist *src_sg;
 	unsigned int cryptlen;
+	struct skcipher_request fallback_req;	// keep at the end
 };
 
 static inline struct qce_alg_template *to_cipher_tmpl(struct crypto_skcipher *tfm)
diff --git a/drivers/crypto/qce/skcipher.c b/drivers/crypto/qce/skcipher.c
index 9412433f3b21..265afae29901 100644
--- a/drivers/crypto/qce/skcipher.c
+++ b/drivers/crypto/qce/skcipher.c
@@ -178,7 +178,7 @@ static int qce_skcipher_setkey(struct crypto_skcipher *ablk, const u8 *key,
 		break;
 	}
 
-	ret = crypto_sync_skcipher_setkey(ctx->fallback, key, keylen);
+	ret = crypto_skcipher_setkey(ctx->fallback, key, keylen);
 	if (!ret)
 		ctx->enc_keylen = keylen;
 	return ret;
@@ -235,16 +235,15 @@ static int qce_skcipher_crypt(struct skcipher_request *req, int encrypt)
 	      req->cryptlen <= aes_sw_max_len) ||
 	     (IS_XTS(rctx->flags) && req->cryptlen > QCE_SECTOR_SIZE &&
 	      req->cryptlen % QCE_SECTOR_SIZE))) {
-		SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback);
-
-		skcipher_request_set_sync_tfm(subreq, ctx->fallback);
-		skcipher_request_set_callback(subreq, req->base.flags,
-					      NULL, NULL);
-		skcipher_request_set_crypt(subreq, req->src, req->dst,
-					   req->cryptlen, req->iv);
-		ret = encrypt ? crypto_skcipher_encrypt(subreq) :
-				crypto_skcipher_decrypt(subreq);
-		skcipher_request_zero(subreq);
+		skcipher_request_set_tfm(&rctx->fallback_req, ctx->fallback);
+		skcipher_request_set_callback(&rctx->fallback_req,
+					      req->base.flags,
+					      req->base.complete,
+					      req->base.data);
+		skcipher_request_set_crypt(&rctx->fallback_req, req->src,
+					   req->dst, req->cryptlen, req->iv);
+		ret = encrypt ? crypto_skcipher_encrypt(&rctx->fallback_req) :
+				crypto_skcipher_decrypt(&rctx->fallback_req);
 		return ret;
 	}
 
@@ -275,8 +274,10 @@ static int qce_skcipher_init_fallback(struct crypto_skcipher *tfm)
 	struct qce_cipher_ctx *ctx = crypto_skcipher_ctx(tfm);
 
 	qce_skcipher_init(tfm);
-	ctx->fallback = crypto_alloc_sync_skcipher(crypto_tfm_alg_name(&tfm->base),
+	ctx->fallback = crypto_alloc_skcipher(crypto_tfm_alg_name(&tfm->base),
 						   0, CRYPTO_ALG_NEED_FALLBACK);
+	crypto_skcipher_set_reqsize(tfm, sizeof(struct qce_cipher_reqctx) +
+					 crypto_skcipher_reqsize(ctx->fallback));
 	return PTR_ERR_OR_ZERO(ctx->fallback);
 }
 
@@ -284,7 +285,7 @@ static void qce_skcipher_exit(struct crypto_skcipher *tfm)
 {
 	struct qce_cipher_ctx *ctx = crypto_skcipher_ctx(tfm);
 
-	crypto_free_sync_skcipher(ctx->fallback);
+	crypto_free_skcipher(ctx->fallback);
 }
 
 struct qce_skcipher_def {
-- 
2.27.0


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  parent reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-25 12:42 [PATCH 00/12] crypto: permit asynchronous skciphers as driver fallbacks Ard Biesheuvel
2020-06-25 12:42 ` [PATCH 01/12] crypto: amlogic-gxl - default to build as module Ard Biesheuvel
2020-06-25 12:42 ` [PATCH 02/12] crypto: amlogic-gxl - permit async skcipher as fallback Ard Biesheuvel
2020-06-25 12:42 ` [PATCH 03/12] crypto: omap-aes - permit asynchronous " Ard Biesheuvel
2020-06-25 12:42 ` [PATCH 04/12] crypto: sun4i " Ard Biesheuvel
2020-06-25 12:42 ` [PATCH 05/12] crypto: sun8i-ce " Ard Biesheuvel
2020-06-25 12:42 ` [PATCH 06/12] crypto: sun8i-ss " Ard Biesheuvel
2020-06-25 12:42 ` [PATCH 07/12] crypto: ccp " Ard Biesheuvel
2020-06-25 16:24   ` kernel test robot
2020-06-25 12:42 ` [PATCH 08/12] crypto: chelsio " Ard Biesheuvel
2020-06-25 12:42 ` [PATCH 09/12] crypto: mxs-dcp " Ard Biesheuvel
2020-06-25 12:42 ` [PATCH 10/12] crypto: picoxcell " Ard Biesheuvel
2020-06-25 12:42 ` Ard Biesheuvel [this message]
2020-06-25 12:42 ` [PATCH 12/12] crypto: sahara " Ard Biesheuvel

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