Le 14/04/2020 à 00:28, Waiman Long a écrit :
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 <long...@redhat.com>
---
  .../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
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