linux-kernel - Re: [PATCH 2/2] crypto: aead,cipher

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Message-ID: <Zhiia00JmkH7hQt8@gondor.apana.org.au>
Date: Fri, 12 Apr 2024 10:54:35 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: Hailey Mothershead <hailmo@...zon.com>
Cc: davem@...emloft.net, linux-crypto@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] crypto: aead,cipher - zeroize key buffer after use

On Thu, Apr 11, 2024 at 11:51:57PM +0000, Hailey Mothershead wrote:
> I.G 9.7.B for FIPS 140-3 specifies that variables temporarily holding
> cryptographic information should be zeroized once they are no longer
> needed. Accomplish this by using kfree_sensitive for buffers that
> previously held the private key.
> 
> Signed-off-by: Hailey Mothershead <hailmo@...zon.com>
> ---
>  crypto/aead.c   | 2 +-
>  crypto/cipher.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/crypto/aead.c b/crypto/aead.c
> index 16991095270d..2592d5375de5 100644
> --- a/crypto/aead.c
> +++ b/crypto/aead.c
> @@ -36,7 +36,7 @@ static int setkey_unaligned(struct crypto_aead *tfm, const u8 *key,
>  	memcpy(alignbuffer, key, keylen);
>  	ret = crypto_aead_alg(tfm)->setkey(tfm, alignbuffer, keylen);
>  	memset(alignbuffer, 0, keylen);
> -	kfree(buffer);
> +	kfree_sensitive(buffer);

Please remove the now-redundant memset.

> diff --git a/crypto/cipher.c b/crypto/cipher.c
> index b47141ed4a9f..efb87fa417e7 100644
> --- a/crypto/cipher.c
> +++ b/crypto/cipher.c
> @@ -35,7 +35,7 @@ static int setkey_unaligned(struct crypto_cipher *tfm, const u8 *key,
>  	memcpy(alignbuffer, key, keylen);
>  	ret = cia->cia_setkey(crypto_cipher_tfm(tfm), alignbuffer, keylen);
>  	memset(alignbuffer, 0, keylen);
> -	kfree(buffer);
> +	kfree_sensitive(buffer);

Ditto.

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