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From:   Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date:   Mon, 9 Sep 2019 13:20:05 +0100
Message-ID: <CAKv+Gu9tVkES12fA0cauMhUV+EZ6HZZwMopJo47qE6j8hsFv4w@mail.gmail.com>
Subject: Re: [PATCH] crypto: ccree - enable CTS support in AES-XTS
To:     Uri Shir <uri.shir@arm.com>
Cc:     Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        Gilad <gilad@benyossef.com>,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
        <linux-crypto@vger.kernel.org>
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On Sun, 8 Sep 2019 at 09:04, Uri Shir <uri.shir@arm.com> wrote:
>
> In XTS encryption/decryption the plaintext byte size
> can be >= AES_BLOCK_SIZE. This patch enable the AES-XTS ciphertext
> stealing implementation in ccree driver.
>
> Signed-off-by: Uri Shir <uri.shir@arm.com>
> ---
>  drivers/crypto/ccree/cc_cipher.c | 16 ++++++----------
>  1 file changed, 6 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/crypto/ccree/cc_cipher.c b/drivers/crypto/ccree/cc_cipher.c
> index 5b58226..a95d3bd 100644
> --- a/drivers/crypto/ccree/cc_cipher.c
> +++ b/drivers/crypto/ccree/cc_cipher.c
> @@ -116,10 +116,6 @@ static int validate_data_size(struct cc_cipher_ctx *ctx_p,
>         case S_DIN_to_AES:
>                 switch (ctx_p->cipher_mode) {
>                 case DRV_CIPHER_XTS:
> -                       if (size >= AES_BLOCK_SIZE &&
> -                           IS_ALIGNED(size, AES_BLOCK_SIZE))
> -                               return 0;
> -                       break;

You should still check for size < block size.

>                 case DRV_CIPHER_CBC_CTS:
>                         if (size >= AES_BLOCK_SIZE)
>                                 return 0;
> @@ -945,7 +941,7 @@ static const struct cc_alg_template skcipher_algs[] = {
>         {
>                 .name = "xts(paes)",
>                 .driver_name = "xts-paes-ccree",
> -               .blocksize = AES_BLOCK_SIZE,
> +               .blocksize = 1,

No need for these blocksize changes - just keep them as they are.

>                 .template_skcipher = {
>                         .setkey = cc_cipher_sethkey,
>                         .encrypt = cc_cipher_encrypt,
> @@ -963,7 +959,7 @@ static const struct cc_alg_template skcipher_algs[] = {
>         {
>                 .name = "xts512(paes)",
>                 .driver_name = "xts-paes-du512-ccree",
> -               .blocksize = AES_BLOCK_SIZE,
> +               .blocksize = 1,
>                 .template_skcipher = {
>                         .setkey = cc_cipher_sethkey,
>                         .encrypt = cc_cipher_encrypt,
> @@ -982,7 +978,7 @@ static const struct cc_alg_template skcipher_algs[] = {
>         {
>                 .name = "xts4096(paes)",
>                 .driver_name = "xts-paes-du4096-ccree",
> -               .blocksize = AES_BLOCK_SIZE,
> +               .blocksize = 1,
>                 .template_skcipher = {
>                         .setkey = cc_cipher_sethkey,
>                         .encrypt = cc_cipher_encrypt,
> @@ -1203,7 +1199,7 @@ static const struct cc_alg_template skcipher_algs[] = {
>         {
>                 .name = "xts(aes)",
>                 .driver_name = "xts-aes-ccree",
> -               .blocksize = AES_BLOCK_SIZE,
> +               .blocksize = 1,
>                 .template_skcipher = {
>                         .setkey = cc_cipher_setkey,
>                         .encrypt = cc_cipher_encrypt,
> @@ -1220,7 +1216,7 @@ static const struct cc_alg_template skcipher_algs[] = {
>         {
>                 .name = "xts512(aes)",
>                 .driver_name = "xts-aes-du512-ccree",
> -               .blocksize = AES_BLOCK_SIZE,
> +               .blocksize = 1,
>                 .template_skcipher = {
>                         .setkey = cc_cipher_setkey,
>                         .encrypt = cc_cipher_encrypt,
> @@ -1238,7 +1234,7 @@ static const struct cc_alg_template skcipher_algs[] = {
>         {
>                 .name = "xts4096(aes)",
>                 .driver_name = "xts-aes-du4096-ccree",
> -               .blocksize = AES_BLOCK_SIZE,
> +               .blocksize = 1,
>                 .template_skcipher = {
>                         .setkey = cc_cipher_setkey,
>                         .encrypt = cc_cipher_encrypt,
> --
> 2.7.4
>