Re: [PATCH v2 2/2] crypto: Remove unnecessary memzero_explicit()
From: Christophe Leroy
Date: Tue Apr 14 2020 - 02:08:53 EST
Le 14/04/2020 Ã 00:28, Waiman Long a ÃcritÂ:
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. For better correctness,
the setting of keylen is also moved down after the key pointer check.
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
---
.../allwinner/sun8i-ce/sun8i-ce-cipher.c | 19 +++++-------------
.../allwinner/sun8i-ss/sun8i-ss-cipher.c | 20 +++++--------------
drivers/crypto/amlogic/amlogic-gxl-cipher.c | 12 +++--------
drivers/crypto/inside-secure/safexcel_hash.c | 3 +--
4 files changed, 14 insertions(+), 40 deletions(-)
diff --git a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
index aa4e8fdc2b32..8358fac98719 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);
}
@@ -391,14 +388,11 @@ 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);
- }
- op->keylen = keylen;
+ kfree_sensitive(op->key);
op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
if (!op->key)
return -ENOMEM;
+ op->keylen = keylen;
Does it matter at all to ensure op->keylen is not set when of->key is
NULL ? I'm not sure.
But if it does, then op->keylen should be set to 0 when freeing op->key.
crypto_sync_skcipher_clear_flags(op->fallback_tfm, CRYPTO_TFM_REQ_MASK);
crypto_sync_skcipher_set_flags(op->fallback_tfm, tfm->base.crt_flags & CRYPTO_TFM_REQ_MASK);
@@ -416,14 +410,11 @@ 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);
- }
- op->keylen = keylen;
+ kfree_sensitive(op->key);
op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
if (!op->key)
return -ENOMEM;
+ op->keylen = keylen;
Same comment as above.
crypto_sync_skcipher_clear_flags(op->fallback_tfm, CRYPTO_TFM_REQ_MASK);
crypto_sync_skcipher_set_flags(op->fallback_tfm, tfm->base.crt_flags & CRYPTO_TFM_REQ_MASK);
diff --git a/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-cipher.c b/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-cipher.c
index 5246ef4f5430..0495fbc27fcc 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);
}
@@ -392,14 +388,11 @@ 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);
- }
- op->keylen = keylen;
+ kfree_sensitive(op->key);
op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
if (!op->key)
return -ENOMEM;
+ op->keylen = keylen;
Same comment as above.
crypto_sync_skcipher_clear_flags(op->fallback_tfm, CRYPTO_TFM_REQ_MASK);
crypto_sync_skcipher_set_flags(op->fallback_tfm, tfm->base.crt_flags & CRYPTO_TFM_REQ_MASK);
@@ -418,14 +411,11 @@ 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);
- }
- op->keylen = keylen;
+ kfree_sensitive(op->key);
op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
if (!op->key)
return -ENOMEM;
+ op->keylen = keylen;
Same comment as above.
crypto_sync_skcipher_clear_flags(op->fallback_tfm, CRYPTO_TFM_REQ_MASK);
crypto_sync_skcipher_set_flags(op->fallback_tfm, tfm->base.crt_flags & CRYPTO_TFM_REQ_MASK);
diff --git a/drivers/crypto/amlogic/amlogic-gxl-cipher.c b/drivers/crypto/amlogic/amlogic-gxl-cipher.c
index fd1269900d67..6aa9ce7bbbd4 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);
}
@@ -368,14 +365,11 @@ 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);
- }
- op->keylen = keylen;
+ kfree_sensitive(op->key);
op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
if (!op->key)
return -ENOMEM;
+ op->keylen = keylen;
Same comment as above.
return crypto_sync_skcipher_setkey(op->fallback_tfm, key, keylen);
}
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;
Christophe