[PATCH v2 8/9] crypto: safexcel - zeroize crypto_aes_ctx with __cleanup(aes_clear_ctx)

[Thomas Huth]

From: Thomas Huth <thuth@xxxxxxxxxx>

The code clears the crypto_aes_ctx in most cases already with
memzero_explicit(), but two cases are missed:

1) safexcel_aead_setkey() never cleared it
2) safexcel_skcipher_aesxts_setkey() runs aes_expandkey() twice, and in
   case the second call fails, the context from the first call is leaked

To fix these and to avoid future similar problems, let's use the new
__cleanup(aes_clear_ctx) mechanism to make sure that we clear the
crypto_aes_ctx everywhere.

Cc: Antoine Tenart <atenart@xxxxxxxxxx>
Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx>
---
 drivers/crypto/inside-secure/safexcel_cipher.c | 15 +++++----------
 drivers/crypto/inside-secure/safexcel_hash.c   |  3 +--
 2 files changed, 6 insertions(+), 12 deletions(-)

diff --git a/drivers/crypto/inside-secure/safexcel_cipher.c b/drivers/crypto/inside-secure/safexcel_cipher.c
index a8349b684693e..2d21ef388beaf 100644
--- a/drivers/crypto/inside-secure/safexcel_cipher.c
+++ b/drivers/crypto/inside-secure/safexcel_cipher.c
@@ -375,7 +375,7 @@ static int safexcel_skcipher_aes_setkey(struct crypto_skcipher *ctfm,
 	struct crypto_tfm *tfm = crypto_skcipher_tfm(ctfm);
 	struct safexcel_cipher_ctx *ctx = crypto_tfm_ctx(tfm);
 	struct safexcel_crypto_priv *priv = ctx->base.priv;
-	struct crypto_aes_ctx aes;
+	struct crypto_aes_ctx aes __cleanup(aes_clear_ctx);
 	int ret, i;
 
 	ret = aes_expandkey(&aes, key, len);
@@ -396,7 +396,6 @@ static int safexcel_skcipher_aes_setkey(struct crypto_skcipher *ctfm,
 
 	ctx->key_len = len;
 
-	memzero_explicit(&aes, sizeof(aes));
 	return 0;
 }
 
@@ -407,7 +406,7 @@ static int safexcel_aead_setkey(struct crypto_aead *ctfm, const u8 *key,
 	struct safexcel_cipher_ctx *ctx = crypto_tfm_ctx(tfm);
 	struct safexcel_crypto_priv *priv = ctx->base.priv;
 	struct crypto_authenc_keys keys;
-	struct crypto_aes_ctx aes;
+	struct crypto_aes_ctx aes __cleanup(aes_clear_ctx);
 	int err = -EINVAL, i;
 	const char *alg;
 
@@ -1362,7 +1361,7 @@ static int safexcel_skcipher_aesctr_setkey(struct crypto_skcipher *ctfm,
 	struct crypto_tfm *tfm = crypto_skcipher_tfm(ctfm);
 	struct safexcel_cipher_ctx *ctx = crypto_tfm_ctx(tfm);
 	struct safexcel_crypto_priv *priv = ctx->base.priv;
-	struct crypto_aes_ctx aes;
+	struct crypto_aes_ctx aes __cleanup(aes_clear_ctx);
 	int ret, i;
 	unsigned int keylen;
 
@@ -1388,7 +1387,6 @@ static int safexcel_skcipher_aesctr_setkey(struct crypto_skcipher *ctfm,
 
 	ctx->key_len = keylen;
 
-	memzero_explicit(&aes, sizeof(aes));
 	return 0;
 }
 
@@ -2542,7 +2540,7 @@ static int safexcel_skcipher_aesxts_setkey(struct crypto_skcipher *ctfm,
 	struct crypto_tfm *tfm = crypto_skcipher_tfm(ctfm);
 	struct safexcel_cipher_ctx *ctx = crypto_tfm_ctx(tfm);
 	struct safexcel_crypto_priv *priv = ctx->base.priv;
-	struct crypto_aes_ctx aes;
+	struct crypto_aes_ctx aes __cleanup(aes_clear_ctx);
 	int ret, i;
 	unsigned int keylen;
 
@@ -2590,7 +2588,6 @@ static int safexcel_skcipher_aesxts_setkey(struct crypto_skcipher *ctfm,
 
 	ctx->key_len = keylen << 1;
 
-	memzero_explicit(&aes, sizeof(aes));
 	return 0;
 }
 
@@ -2756,12 +2753,11 @@ static int safexcel_aead_ccm_setkey(struct crypto_aead *ctfm, const u8 *key,
 	struct crypto_tfm *tfm = crypto_aead_tfm(ctfm);
 	struct safexcel_cipher_ctx *ctx = crypto_tfm_ctx(tfm);
 	struct safexcel_crypto_priv *priv = ctx->base.priv;
-	struct crypto_aes_ctx aes;
+	struct crypto_aes_ctx aes __cleanup(aes_clear_ctx);
 	int ret, i;
 
 	ret = aes_expandkey(&aes, key, len);
 	if (ret) {
-		memzero_explicit(&aes, sizeof(aes));
 		return ret;
 	}
 
@@ -2790,7 +2786,6 @@ static int safexcel_aead_ccm_setkey(struct crypto_aead *ctfm, const u8 *key,
 	else
 		ctx->hash_alg = CONTEXT_CONTROL_CRYPTO_ALG_XCBC128;
 
-	memzero_explicit(&aes, sizeof(aes));
 	return 0;
 }
 
diff --git a/drivers/crypto/inside-secure/safexcel_hash.c b/drivers/crypto/inside-secure/safexcel_hash.c
index 3402e570d045c..d3b701c96d871 100644
--- a/drivers/crypto/inside-secure/safexcel_hash.c
+++ b/drivers/crypto/inside-secure/safexcel_hash.c
@@ -1905,7 +1905,7 @@ static int safexcel_cbcmac_setkey(struct crypto_ahash *tfm, const u8 *key,
 				 unsigned int len)
 {
 	struct safexcel_ahash_ctx *ctx = crypto_tfm_ctx(crypto_ahash_tfm(tfm));
-	struct crypto_aes_ctx aes;
+	struct crypto_aes_ctx aes __cleanup(aes_clear_ctx);
 	int ret, i;
 
 	ret = aes_expandkey(&aes, key, len);
@@ -1928,7 +1928,6 @@ static int safexcel_cbcmac_setkey(struct crypto_ahash *tfm, const u8 *key,
 	}
 	ctx->cbcmac  = true;
 
-	memzero_explicit(&aes, sizeof(aes));
 	return 0;
 }
 
-- 
2.55.0