[PATCH] KEYS: use kfree_sensitive with key

[PATCH] KEYS: use kfree_sensitive with key

[Mahmoud Adam]

key member might contain private part of the key, so better use
kfree_sensitive to free it

Signed-off-by: Mahmoud Adam <mngyadam@amazon.com>
---
 crypto/asymmetric_keys/public_key.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index eca5671ad3f2..006ae170a16f 100644
--- a/crypto/asymmetric_keys/public_key.c
+++ b/crypto/asymmetric_keys/public_key.c
@@ -43,7 +43,7 @@ static void public_key_describe(const struct key *asymmetric_key,
 void public_key_free(struct public_key *key)
 {
 	if (key) {
-		kfree(key->key);
+		kfree_sensitive(key->key);
 		kfree(key->params);
 		kfree(key);
 	}
@@ -218,7 +218,7 @@ static int software_key_query(const struct kernel_pkey_params *params,
 	ret = 0;
 
 error_free_key:
-	kfree(key);
+	kfree_sensitive(key);
 error_free_tfm:
 	crypto_free_akcipher(tfm);
 	pr_devel("<==%s() = %d\n", __func__, ret);
@@ -303,7 +303,7 @@ static int software_key_eds_op(struct kernel_pkey_params *params,
 		ret = req->dst_len;
 
 error_free_key:
-	kfree(key);
+	kfree_sensitive(key);
 error_free_req:
 	akcipher_request_free(req);
 error_free_tfm:
@@ -456,7 +456,7 @@ int public_key_verify_signature(const struct public_key *pkey,
 	ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait);
 
 error_free_key:
-	kfree(key);
+	kfree_sensitive(key);
 error_free_req:
 	akcipher_request_free(req);
 error_free_tfm:
-- 
2.40.1

Re: [PATCH] KEYS: use kfree_sensitive with key

[Herbert Xu]

On Tue, Jun 13, 2023 at 04:07:23PM +0000, Mahmoud Adam wrote:
> key member might contain private part of the key, so better use
> kfree_sensitive to free it
> 
> Signed-off-by: Mahmoud Adam <mngyadam@amazon.com>
> ---
>  crypto/asymmetric_keys/public_key.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
> index eca5671ad3f2..006ae170a16f 100644
> --- a/crypto/asymmetric_keys/public_key.c
> +++ b/crypto/asymmetric_keys/public_key.c
> @@ -43,7 +43,7 @@ static void public_key_describe(const struct key *asymmetric_key,
>  void public_key_free(struct public_key *key)
>  {
>  	if (key) {
> -		kfree(key->key);
> +		kfree_sensitive(key->key);

The public key should not be freed with kfree_sensitive.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCH] KEYS: use kfree_sensitive with key

[Adam, Mahmoud]

> On 14. Jun 2023, at 11:49, Herbert Xu <herbert@gondor.apana.org.au> wrote:
> 
> On Tue, Jun 13, 2023 at 04:07:23PM +0000, Mahmoud Adam wrote:
>> key member might contain private part of the key, so better use
>> kfree_sensitive to free it
>> 
>> Signed-off-by: Mahmoud Adam <mngyadam@amazon.com>
>> ---
>> crypto/asymmetric_keys/public_key.c | 8 ++++----
>> 1 file changed, 4 insertions(+), 4 deletions(-)
>> 
>> diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
>> index eca5671ad3f2..006ae170a16f 100644
>> --- a/crypto/asymmetric_keys/public_key.c
>> +++ b/crypto/asymmetric_keys/public_key.c
>> @@ -43,7 +43,7 @@ static void public_key_describe(const struct key *asymmetric_key,
>> void public_key_free(struct public_key *key)
>> {
>> if (key) {
>> - kfree(key->key);
>> + kfree_sensitive(key->key);
> 
> The public key should not be freed with kfree_sensitive.

I think this holds for the other lines as well, I can use pkey->key_is_private to check for them also

Thanks.




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Re: [PATCH] KEYS: use kfree_sensitive with key

[Herbert Xu]

On Wed, Jun 14, 2023 at 01:32:51PM +0000, Adam, Mahmoud wrote:
>
> I think this holds for the other lines as well, I can use pkey->key_is_private to check for them also

That might be going a bit overboard.

So if the key is definitely public, then use kfree.  If we don't
know what it is (i.e., public or private), then just use kfree_sensitive.

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt