2023-06-13 16:13:14

by Mahmoud Adam

Subject: [PATCH] KEYS: use kfree_sensitive with key

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

Signed-off-by: Mahmoud Adam <[email protected]>
---
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

2023-06-14 09:56:41

by Herbert Xu

Subject: Re: [PATCH] KEYS: use kfree_sensitive with key

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 <[email protected]>
> ---
> 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 <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

2023-06-14 13:34:39

by Adam, Mahmoud

Subject: Re: [PATCH] KEYS: use kfree_sensitive with key

> On 14. Jun 2023, at 11:49, Herbert Xu <[email protected]> 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 <[email protected]>
>> ---
>> 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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2023-06-15 09:15:24

by Herbert Xu

Subject: Re: [PATCH] KEYS: use kfree_sensitive with key

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 <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt