Re: [PATCH v3 2/3] crypto: Remove unnecessary memzero_explicit()
From: Corentin Labbe
Date: Thu Apr 16 2020 - 05:08:38 EST
On Tue, Apr 14, 2020 at 04:02:14PM -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. For better correctness,
> keylen is cleared if key memory allocation fails.
>
> Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
> ---
> .../allwinner/sun8i-ce/sun8i-ce-cipher.c | 23 +++++++-----------
> .../allwinner/sun8i-ss/sun8i-ss-cipher.c | 24 +++++++------------
> drivers/crypto/amlogic/amlogic-gxl-cipher.c | 14 ++++-------
> drivers/crypto/inside-secure/safexcel_hash.c | 3 +--
> 4 files changed, 24 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..a2bac10d2876 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 +388,13 @@ 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)
> + if (unlikely(!op->key)) {
> + op->keylen = 0;
> return -ENOMEM;
> + }
>
> 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 +412,13 @@ 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);
> - }
> + kfree_sensitive(op->key);
> op->keylen = keylen;
> op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
> - if (!op->key)
> + if (unlikely(!op->key)) {
> + op->keylen = 0;
> return -ENOMEM;
> + }
>
> 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..a24d567a6c36 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 +388,13 @@ 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)
> + if (unlikely(!op->key))
> + op->keylen = 0;
> return -ENOMEM;
> + }
>
> 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 +413,13 @@ 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)
> + if (unlikely(!op->key))
> + op->keylen = 0;
> return -ENOMEM;
> + }
>
> 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..5312bad7534e 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 +365,13 @@ 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)
> + if (unlikely(!op->key))
> + op->keylen = 0;
> return -ENOMEM;
> + }
>
> return crypto_sync_skcipher_setkey(op->fallback_tfm, key, keylen);
> }
For sun8i-ss/sun8i-ce
Acked-by: Corentin Labbe <clabbe.montjoie@xxxxxxxxx>
For amlogic
Acked-by: Corentin Labbe <clabbe@xxxxxxxxxxxx>
Thanks