linux-kernel - Re: [PATCH 2/2] crypto: vmx - Use skcipher for xts fallback

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Message-ID: <20170222192004.GC20626@gallifrey>
Date:   Wed, 22 Feb 2017 16:20:04 -0300
From:   Marcelo Cerri <marcelo.cerri@...onical.com>
To:     Paulo Flabiano Smorigo <pfsmorigo@...ux.vnet.ibm.com>
Cc:     linux-kernel@...r.kernel.org, benh@...nel.crashing.org,
        paulus@...ba.org, mpe@...erman.id.au, herbert@...dor.apana.org.au,
        davem@...emloft.net, linux-crypto@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH 2/2] crypto: vmx - Use skcipher for xts fallback

In addition to cbc comments:

On Wed, Feb 22, 2017 at 03:00:45PM -0300, Paulo Flabiano Smorigo wrote:
> Signed-off-by: Paulo Flabiano Smorigo <pfsmorigo@...ux.vnet.ibm.com>
> ---
>  drivers/crypto/vmx/aes_xts.c | 32 ++++++++++++++++++--------------
>  1 file changed, 18 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/crypto/vmx/aes_xts.c b/drivers/crypto/vmx/aes_xts.c
> index 24353ec3..a8245e1 100644
> --- a/drivers/crypto/vmx/aes_xts.c
> +++ b/drivers/crypto/vmx/aes_xts.c
> @@ -28,11 +28,12 @@
>  #include <crypto/aes.h>
>  #include <crypto/scatterwalk.h>
>  #include <crypto/xts.h>
> +#include <crypto/internal/skcipher.h>
>  
>  #include "aesp8-ppc.h"
>  
>  struct p8_aes_xts_ctx {
> -	struct crypto_blkcipher *fallback;
> +	struct crypto_skcipher *fallback;
>  	struct aes_key enc_key;
>  	struct aes_key dec_key;
>  	struct aes_key tweak_key;
> @@ -41,7 +42,7 @@ struct p8_aes_xts_ctx {
>  static int p8_aes_xts_init(struct crypto_tfm *tfm)
>  {
>  	const char *alg;
> -	struct crypto_blkcipher *fallback;
> +	struct crypto_skcipher *fallback;
>  	struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm);
>  
>  	if (!(alg = crypto_tfm_alg_name(tfm))) {
> @@ -50,7 +51,7 @@ static int p8_aes_xts_init(struct crypto_tfm *tfm)
>  	}
>  
>  	fallback =
> -		crypto_alloc_blkcipher(alg, 0, CRYPTO_ALG_NEED_FALLBACK);
> +		crypto_alloc_skcipher(alg, 0, CRYPTO_ALG_NEED_FALLBACK);
>  	if (IS_ERR(fallback)) {
>  		printk(KERN_ERR
>  			"Failed to allocate transformation for '%s': %ld\n",
> @@ -60,9 +61,9 @@ static int p8_aes_xts_init(struct crypto_tfm *tfm)
>  	printk(KERN_INFO "Using '%s' as fallback implementation.\n",
>  		crypto_tfm_alg_driver_name((struct crypto_tfm *) fallback));
>  
> -	crypto_blkcipher_set_flags(
> +	crypto_skcipher_set_flags(
>  		fallback,
> -		crypto_blkcipher_get_flags((struct crypto_blkcipher *)tfm));
> +		crypto_skcipher_get_flags((struct crypto_skcipher *)tfm));
>  	ctx->fallback = fallback;
>  
>  	return 0;
> @@ -73,7 +74,7 @@ static void p8_aes_xts_exit(struct crypto_tfm *tfm)
>  	struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm);
>  
>  	if (ctx->fallback) {
> -		crypto_free_blkcipher(ctx->fallback);
> +		crypto_free_skcipher(ctx->fallback);
>  		ctx->fallback = NULL;
>  	}
>  }
> @@ -98,7 +99,7 @@ static int p8_aes_xts_setkey(struct crypto_tfm *tfm, const u8 *key,
>  	pagefault_enable();
>  	preempt_enable();
>  
> -	ret += crypto_blkcipher_setkey(ctx->fallback, key, keylen);
> +	ret += crypto_skcipher_setkey(ctx->fallback, key, keylen);
>  	return ret;
>  }
>  
> @@ -113,15 +114,18 @@ static int p8_aes_xts_crypt(struct blkcipher_desc *desc,
>  	struct blkcipher_walk walk;
>  	struct p8_aes_xts_ctx *ctx =
>  		crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
> -	struct blkcipher_desc fallback_desc = {
> -		.tfm = ctx->fallback,
> -		.info = desc->info,
> -		.flags = desc->flags
> -	};
>  
>  	if (in_interrupt()) {
> -		ret = enc ? crypto_blkcipher_encrypt(&fallback_desc, dst, src, nbytes) :
> -                            crypto_blkcipher_decrypt(&fallback_desc, dst, src, nbytes);
> +		SKCIPHER_REQUEST_ON_STACK(req, ctx->fallback);
> +		skcipher_request_set_tfm(req, ctx->fallback);
> +		skcipher_request_set_callback(req, desc->flags, NULL, NULL);
> +		skcipher_request_set_crypt(req, src, dst, nbytes, desc->info);
> +		ret = crypto_skcipher_encrypt(req);

You probably don't want this crypto_skcipher_encrypt call.


> +		if (enc)
> +			crypto_skcipher_encrypt(req);
> +		else
> +			crypto_skcipher_decrypt(req);

And you should check the return values here.

> +		skcipher_request_zero(req);
>  	} else {
>  		preempt_disable();
>  		pagefault_disable();
> -- 
> 2.9.3
> 

-- 
Regards,
Marcelo


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