Re: [PATCH 8/9] Validate input parameters for libfsverity_sign_digest()

From: Eric Biggers <ebiggers@kernel.org>
To: Jes Sorensen <jes.sorensen@gmail.com>
Cc: linux-fscrypt@vger.kernel.org, kernel-team@fb.com,
	Jes Sorensen <jsorensen@fb.com>
Subject: Re: [PATCH 8/9] Validate input parameters for libfsverity_sign_digest()
Date: Sat, 21 Mar 2020 22:27:04 -0700	[thread overview]
Message-ID: <20200322052704.GF111151@sol.localdomain> (raw)
In-Reply-To: <20200312214758.343212-9-Jes.Sorensen@gmail.com>

On Thu, Mar 12, 2020 at 05:47:57PM -0400, Jes Sorensen wrote:
> From: Jes Sorensen <jsorensen@fb.com>
> 
> Return -EINVAL on any invalid input argument, as well
> as if any of the reserved fields are set in
> struct libfsverity_signature_digest
> 
> Signed-off-by: Jes Sorensen <jsorensen@fb.com>
> ---
>  libverity.c | 34 ++++++++++++++++++++++++++--------
>  1 file changed, 26 insertions(+), 8 deletions(-)
> 
> diff --git a/libverity.c b/libverity.c
> index 1cef544..e16306d 100644
> --- a/libverity.c
> +++ b/libverity.c
> @@ -494,18 +494,36 @@ libfsverity_sign_digest(const struct libfsverity_digest *digest,
>  	X509 *cert = NULL;
>  	const EVP_MD *md;
>  	size_t data_size;
> -	uint16_t alg_nr;
> -	int retval = -EAGAIN;
> +	uint16_t alg_nr, digest_size;
> +	int i, retval = -EAGAIN;
> +	const char magic[8] = "FSVerity";
> +
> +	if (!digest || !sig_params || !sig_ret || !sig_size_ret)
> +		return -EINVAL;
> +
> +	if (strncmp(digest->magic, magic, sizeof(magic)))
> +		return -EINVAL;
> +
> +	if (!sig_params->keyfile || !sig_params->certfile)
> +		return -EINVAL;
> +
> +	for (i = 0; i < sizeof(sig_params->reserved) /
> +		     sizeof(sig_params->reserved[0]); i++) {
> +		if (sig_params->reserved[i])
> +			return -EINVAL;
> +	}

This can use ARRAY_SIZE().

- Eric