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From: Eric Biggers <ebiggers@kernel.org>
To: "Stephan Müller" <smueller@chronox.de>
Cc: herbert@gondor.apana.org.au, Jarkko Sakkinen <jarkko@kernel.org>,
	mathew.j.martineau@linux.intel.com, dhowells@redhat.com,
	linux-crypto@vger.kernel.org, linux-fscrypt@vger.kernel.org,
	linux-kernel@vger.kernel.org, keyrings@vger.kernel.org,
	simo@redhat.com
Subject: Re: [PATCH v2 6/7] fs: use HKDF implementation from kernel crypto API
Date: Thu, 28 Jan 2021 12:18:12 -0800
Message-ID: <YBMcBPXrKswTyiMC@sol.localdomain> (raw)
In-Reply-To: <3577027.kQq0lBPeGt@positron.chronox.de>

On Sun, Jan 24, 2021 at 03:04:31PM +0100, Stephan Müller wrote:
> @@ -74,16 +57,14 @@ int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key,
>  		return PTR_ERR(hmac_tfm);
>  	}
>  
> -	if (WARN_ON(crypto_shash_digestsize(hmac_tfm) != sizeof(prk))) {
> +	if (WARN_ON(crypto_shash_digestsize(hmac_tfm) != HKDF_HASHLEN)) {
>  		err = -EINVAL;
>  		goto err_free_tfm;
>  	}
>  
> -	err = hkdf_extract(hmac_tfm, master_key, master_key_size, prk);
> -	if (err)
> -		goto err_free_tfm;
> -
> -	err = crypto_shash_setkey(hmac_tfm, prk, sizeof(prk));
> +	/* HKDF-Extract (RFC 5869 section 2.2), unsalted */
> +	err = crypto_hkdf_extract(hmac_tfm, NULL, 0,
> +				  master_key, master_key_size);
>  	if (err)
>  		goto err_free_tfm;
>  
> @@ -93,7 +74,6 @@ int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key,
>  err_free_tfm:
>  	crypto_free_shash(hmac_tfm);
>  out:
> -	memzero_explicit(prk, sizeof(prk));
>  	return err;
>  }

The 'out' label isn't needed anymore.  'goto out' should be replaced with
'return 0'.

- Eric

  parent reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-24 14:01 [PATCH v2 0/7] Add KDF implementations to " Stephan Müller
2021-01-24 14:01 ` [PATCH v2 1/7] crypto: Add key derivation self-test support code Stephan Müller
2021-01-24 14:02 ` [PATCH v2 2/7] crypto: add SP800-108 counter key derivation function Stephan Müller
2021-01-24 14:03 ` [PATCH v2 3/7] crypto: add RFC5869 HKDF Stephan Müller
2021-01-28 20:08   ` Eric Biggers
2021-01-24 14:03 ` [PATCH v2 4/7] security: DH - remove dead code for zero padding Stephan Müller
2021-01-24 14:04 ` [PATCH v2 5/7] security: DH - use KDF implementation from crypto API Stephan Müller
2021-01-24 14:04 ` [PATCH v2 6/7] fs: use HKDF implementation from kernel " Stephan Müller
2021-01-28 20:16   ` Eric Biggers
2021-01-28 20:18   ` Eric Biggers [this message]
2021-01-24 14:04 ` [PATCH v2 7/7] fs: HKDF - remove duplicate memory clearing Stephan Müller
2021-01-28 20:21   ` Eric Biggers
2021-01-24 14:23 ` [PATCH v2 0/7] Add KDF implementations to crypto API Ard Biesheuvel
2021-01-24 14:32   ` Ard Biesheuvel
2021-01-24 14:36     ` Stephan Müller
2021-01-24 14:34   ` Stephan Müller

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