diff mbox series

[2/2] crypto: Remove unnecessary memzero_explicit()

Message ID 20200413211550.8307-3-longman@redhat.com (mailing list archive)
State Not Applicable
Delegated to: Herbert Xu
Headers show
Series mm, treewide: Rename kzfree() to kfree_sensitive() | expand

Commit Message

Waiman Long April 13, 2020, 9:15 p.m. UTC 
Since kfree_sensitive() will do an implicit memzero_explicit(), there
is no need to call memzero_explicit() before it. Eliminate those
memzero_explicit() and simplify the call sites.

Signed-off-by: Waiman Long <longman@redhat.com>
---
 .../crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c  | 15 +++------------
 .../crypto/allwinner/sun8i-ss/sun8i-ss-cipher.c  | 16 +++-------------
 drivers/crypto/amlogic/amlogic-gxl-cipher.c      | 10 ++--------
 drivers/crypto/inside-secure/safexcel_hash.c     |  3 +--
 4 files changed, 9 insertions(+), 35 deletions(-)

Comments

Joe Perches April 13, 2020, 9:31 p.m. UTC | #1 
On Mon, 2020-04-13 at 17:15 -0400, Waiman Long wrote:
> Since kfree_sensitive() will do an implicit memzero_explicit(), there
> is no need to call memzero_explicit() before it. Eliminate those
> memzero_explicit() and simplify the call sites.

2 bits of trivia:

> diff --git a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
[]
> @@ -391,10 +388,7 @@ int sun8i_ce_aes_setkey(struct crypto_skcipher *tfm, const u8 *key,
>  		dev_dbg(ce->dev, "ERROR: Invalid keylen %u\n", keylen);
>  		return -EINVAL;
>  	}
> -	if (op->key) {
> -		memzero_explicit(op->key, op->keylen);
> -		kfree(op->key);
> -	}
> +	kfree_sensitive(op->key);
>  	op->keylen = keylen;
>  	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
>  	if (!op->key)

It might be a defect to set op->keylen before the kmemdup succeeds.

> @@ -416,10 +410,7 @@ int sun8i_ce_des3_setkey(struct crypto_skcipher *tfm, const u8 *key,
>  	if (err)
>  		return err;
>  
> -	if (op->key) {
> -		memzero_explicit(op->key, op->keylen);
> -		kfree(op->key);
> -	}
> +	free_sensitive(op->key, op->keylen);

Why not kfree_sensitive(op->key) ?
Waiman Long April 13, 2020, 9:52 p.m. UTC | #2 
On 4/13/20 5:31 PM, Joe Perches wrote:
> On Mon, 2020-04-13 at 17:15 -0400, Waiman Long wrote:
>> Since kfree_sensitive() will do an implicit memzero_explicit(), there
>> is no need to call memzero_explicit() before it. Eliminate those
>> memzero_explicit() and simplify the call sites.
> 2 bits of trivia:
>
>> diff --git a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
> []
>> @@ -391,10 +388,7 @@ int sun8i_ce_aes_setkey(struct crypto_skcipher *tfm, const u8 *key,
>>  		dev_dbg(ce->dev, "ERROR: Invalid keylen %u\n", keylen);
>>  		return -EINVAL;
>>  	}
>> -	if (op->key) {
>> -		memzero_explicit(op->key, op->keylen);
>> -		kfree(op->key);
>> -	}
>> +	kfree_sensitive(op->key);
>>  	op->keylen = keylen;
>>  	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
>>  	if (!op->key)
> It might be a defect to set op->keylen before the kmemdup succeeds.
It could be. I can move it down after the op->key check.
>> @@ -416,10 +410,7 @@ int sun8i_ce_des3_setkey(struct crypto_skcipher *tfm, const u8 *key,
>>  	if (err)
>>  		return err;
>>  
>> -	if (op->key) {
>> -		memzero_explicit(op->key, op->keylen);
>> -		kfree(op->key);
>> -	}
>> +	free_sensitive(op->key, op->keylen);
> Why not kfree_sensitive(op->key) ?

Oh, it is a bug. I will send out v2 to fix that.

Thanks for spotting it.

Cheers,
Longman


>
>
diff mbox series

Patch

diff --git a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
index aa4e8fdc2b32..46c10c7ca6d0 100644
--- a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
+++ b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
@@ -366,10 +366,7 @@  void sun8i_ce_cipher_exit(struct crypto_tfm *tfm)
 {
 	struct sun8i_cipher_tfm_ctx *op = crypto_tfm_ctx(tfm);
 
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
+	kfree_sensitive(op->key);
 	crypto_free_sync_skcipher(op->fallback_tfm);
 	pm_runtime_put_sync_suspend(op->ce->dev);
 }
@@ -391,10 +388,7 @@  int sun8i_ce_aes_setkey(struct crypto_skcipher *tfm, const u8 *key,
 		dev_dbg(ce->dev, "ERROR: Invalid keylen %u\n", keylen);
 		return -EINVAL;
 	}
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
+	kfree_sensitive(op->key);
 	op->keylen = keylen;
 	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
 	if (!op->key)
@@ -416,10 +410,7 @@  int sun8i_ce_des3_setkey(struct crypto_skcipher *tfm, const u8 *key,
 	if (err)
 		return err;
 
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
+	free_sensitive(op->key, op->keylen);
 	op->keylen = keylen;
 	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
 	if (!op->key)
diff --git a/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-cipher.c b/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-cipher.c
index 5246ef4f5430..7e09a923cbaf 100644
--- a/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-cipher.c
+++ b/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-cipher.c
@@ -249,7 +249,6 @@  static int sun8i_ss_cipher(struct skcipher_request *areq)
 			offset = areq->cryptlen - ivsize;
 			if (rctx->op_dir & SS_DECRYPTION) {
 				memcpy(areq->iv, backup_iv, ivsize);
-				memzero_explicit(backup_iv, ivsize);
 				kfree_sensitive(backup_iv);
 			} else {
 				scatterwalk_map_and_copy(areq->iv, areq->dst, offset,
@@ -367,10 +366,7 @@  void sun8i_ss_cipher_exit(struct crypto_tfm *tfm)
 {
 	struct sun8i_cipher_tfm_ctx *op = crypto_tfm_ctx(tfm);
 
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
+	kfree_sensitive(op->key);
 	crypto_free_sync_skcipher(op->fallback_tfm);
 	pm_runtime_put_sync(op->ss->dev);
 }
@@ -392,10 +388,7 @@  int sun8i_ss_aes_setkey(struct crypto_skcipher *tfm, const u8 *key,
 		dev_dbg(ss->dev, "ERROR: Invalid keylen %u\n", keylen);
 		return -EINVAL;
 	}
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
+	kfree_sensitive(op->key);
 	op->keylen = keylen;
 	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
 	if (!op->key)
@@ -418,10 +411,7 @@  int sun8i_ss_des3_setkey(struct crypto_skcipher *tfm, const u8 *key,
 		return -EINVAL;
 	}
 
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
+	kfree_sensitive(op->key);
 	op->keylen = keylen;
 	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
 	if (!op->key)
diff --git a/drivers/crypto/amlogic/amlogic-gxl-cipher.c b/drivers/crypto/amlogic/amlogic-gxl-cipher.c
index fd1269900d67..f424397fbba4 100644
--- a/drivers/crypto/amlogic/amlogic-gxl-cipher.c
+++ b/drivers/crypto/amlogic/amlogic-gxl-cipher.c
@@ -341,10 +341,7 @@  void meson_cipher_exit(struct crypto_tfm *tfm)
 {
 	struct meson_cipher_tfm_ctx *op = crypto_tfm_ctx(tfm);
 
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
+	kfree_sensitive(op->key)
 	crypto_free_sync_skcipher(op->fallback_tfm);
 }
 
@@ -368,10 +365,7 @@  int meson_aes_setkey(struct crypto_skcipher *tfm, const u8 *key,
 		dev_dbg(mc->dev, "ERROR: Invalid keylen %u\n", keylen);
 		return -EINVAL;
 	}
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
+	kfree_sensitive(op->key);
 	op->keylen = keylen;
 	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
 	if (!op->key)
diff --git a/drivers/crypto/inside-secure/safexcel_hash.c b/drivers/crypto/inside-secure/safexcel_hash.c
index 43962bc709c6..4a2d162914de 100644
--- a/drivers/crypto/inside-secure/safexcel_hash.c
+++ b/drivers/crypto/inside-secure/safexcel_hash.c
@@ -1081,8 +1081,7 @@  static int safexcel_hmac_init_pad(struct ahash_request *areq,
 		}
 
 		/* Avoid leaking */
-		memzero_explicit(keydup, keylen);
-		kfree(keydup);
+		kfree_sensitive(keydup);
 
 		if (ret)
 			return ret;