[dm-devel] [PATCH 1/3 v2] crypto: introduce the flag CRYPTO_ALG_ALLOCATES_MEMORY

[Eric Biggers]

On Fri, Jun 26, 2020 at 12:16:33PM -0400, Mikulas Patocka wrote:
> +/*
> + * Pass these flags down through the crypto API.
> + */
> +#define CRYPTO_ALG_INHERITED_FLAGS	(CRYPTO_ALG_ASYNC | CRYPTO_ALG_ALLOCATES_MEMORY)

This comment is useless.  How about:

/*
 * When an algorithm uses another algorithm (e.g., if it's an instance of a
 * template), these are the flags that always get set on the "outer" algorithm
 * if any "inner" algorithm has them set.  In some cases other flags are
 * inherited too; these are just the flags that are *always* inherited.
 */
#define CRYPTO_ALG_INHERITED_FLAGS	(CRYPTO_ALG_ASYNC | CRYPTO_ALG_ALLOCATES_MEMORY)

Also I wonder about the case where the inner algorithm is a fallback rather than
part of a template instance.  This patch only handles templates, not fallbacks.
Is that intentional?  Isn't that technically a bug?

> +
> +/*
>   * Transform masks and values (for crt_flags).
>   */
>  #define CRYPTO_TFM_NEED_KEY		0x00000001
> Index: linux-2.6/crypto/authenc.c
> ===================================================================
> --- linux-2.6.orig/crypto/authenc.c	2020-06-26 17:24:03.566417000 +0200
> +++ linux-2.6/crypto/authenc.c	2020-06-26 17:24:03.566417000 +0200
> @@ -388,7 +388,8 @@ static int crypto_authenc_create(struct
>  	if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
>  		return -EINVAL;
>  
> -	mask = crypto_requires_sync(algt->type, algt->mask);
> +	mask = crypto_requires_sync(algt->type, algt->mask) |
> +	       crypto_requires_nomem(algt->type, algt->mask);

As I suggested earlier, shouldn't there be a function that returns the mask for
all inherited flags, rather than handling each flag individually?

>  
>  	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
>  	if (!inst)
> @@ -424,7 +425,7 @@ static int crypto_authenc_create(struct
>  		goto err_free_inst;
>  
>  	inst->alg.base.cra_flags = (auth_base->cra_flags |
> -				    enc->base.cra_flags) & CRYPTO_ALG_ASYNC;
> +			enc->base.cra_flags) & CRYPTO_ALG_INHERITED_FLAGS;

Strange indentation here.  Likewise in most of the other files.

> Index: linux-2.6/crypto/xts.c
> ===================================================================
> --- linux-2.6.orig/crypto/xts.c	2020-06-26 17:24:03.566417000 +0200
> +++ linux-2.6/crypto/xts.c	2020-06-26 17:24:03.566417000 +0200
> @@ -415,7 +415,7 @@ static int create(struct crypto_template
>  	} else
>  		goto err_free_inst;
>  
> -	inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
> +	inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_INHERITED_FLAGS;
>  	inst->alg.base.cra_priority = alg->base.cra_priority;
>  	inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE;
>  	inst->alg.base.cra_alignmask = alg->base.cra_alignmask |

Need to set the mask correctly in this file.

> Index: linux-2.6/crypto/adiantum.c
> ===================================================================
> --- linux-2.6.orig/crypto/adiantum.c	2020-06-26 17:24:03.566417000 +0200
> +++ linux-2.6/crypto/adiantum.c	2020-06-26 17:24:03.566417000 +0200
> @@ -507,7 +507,8 @@ static int adiantum_create(struct crypto
>  	if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
>  		return -EINVAL;
>  
> -	mask = crypto_requires_sync(algt->type, algt->mask);
> +	mask = crypto_requires_sync(algt->type, algt->mask) |
> +	       crypto_requires_nomem(algt->type, algt->mask);
>  
>  	inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
>  	if (!inst)

Need to use CRYPTO_ALG_INHERITED_FLAGS in this file.

- Eric