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Re: [dm-devel] [PATCH 1/3] dm crypt: wipe keys string immediately after key is set



On Wed, Feb 02 2011 at  7:08pm -0500,
Milan Broz <mbroz redhat com> wrote:

> If the tfm key was set up correctly, do not keep another
> copy of key and immediately replace it with zero string.
> 
> Signed-off-by: Milan Broz <mbroz redhat com>
> ---
>  drivers/md/dm-crypt.c |   16 +++++++++++-----
>  1 files changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
> index 4e054bd..d748433 100644
> --- a/drivers/md/dm-crypt.c
> +++ b/drivers/md/dm-crypt.c
> @@ -1331,20 +1331,26 @@ static int crypt_setkey_allcpus(struct crypt_config *cc)
>  
>  static int crypt_set_key(struct crypt_config *cc, char *key)
>  {
> +	int r = -EINVAL, key_string_len = strlen(key);
> +
>  	/* The key size may not be changed. */
> -	if (cc->key_size != (strlen(key) >> 1))
> -		return -EINVAL;
> +	if (cc->key_size != (key_string_len >> 1))
> +		goto out;
>  
>  	/* Hyphen (which gives a key_size of zero) means there is no key. */
>  	if (!cc->key_size && strcmp(key, "-"))
> -		return -EINVAL;
> +		goto out;
>  
>  	if (cc->key_size && crypt_decode_key(cc->key, key, cc->key_size) < 0)
> -		return -EINVAL;
> +		goto out;
>  
>  	set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
>  
> -	return crypt_setkey_allcpus(cc);
> +	r = crypt_setkey_allcpus(cc);
> +out:
> +	/* Wipe hexa key string as soon as possible */

s/hexa/hex/ ?

> +	memset(key, '0', key_string_len);
> +	return r;
>  }
>  
>  static int crypt_wipe_key(struct crypt_config *cc)

Acked-by: Mike Snitzer <snitzer redhat com>


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