Re: [PATCH] crypto: arm64: CE: implement export/import

[Eric Biggers]

On Wed, Feb 19, 2020 at 04:00:37PM +0000, Corentin Labbe wrote:
> When an ahash algorithm fallback to another ahash and that fallback is
> shaXXX-CE, doing export/import lead to error like this:
> alg: ahash: sha1-sun8i-ce export() overran state buffer on test vector 0, cfg=\"import/export\"
> 
> This is due to the descsize of shaxxx-ce larger than struct shaxxx_state off by an u32.
> For fixing this, let's implement export/import which rip the finalize
> variant instead of using generic export/import.
> 
> Signed-off-by: Corentin Labbe <clabbe@xxxxxxxxxxxx>
> ---
>  arch/arm64/crypto/sha1-ce-glue.c | 20 ++++++++++++++++++++
>  arch/arm64/crypto/sha2-ce-glue.c | 23 +++++++++++++++++++++++
>  2 files changed, 43 insertions(+)
> 
> diff --git a/arch/arm64/crypto/sha1-ce-glue.c b/arch/arm64/crypto/sha1-ce-glue.c
> index 63c875d3314b..dc44d48415cd 100644
> --- a/arch/arm64/crypto/sha1-ce-glue.c
> +++ b/arch/arm64/crypto/sha1-ce-glue.c
> @@ -91,12 +91,32 @@ static int sha1_ce_final(struct shash_desc *desc, u8 *out)
>  	return sha1_base_finish(desc, out);
>  }
>  
> +static int sha1_ce_export(struct shash_desc *desc, void *out)
> +{
> +	struct sha1_ce_state *sctx = shash_desc_ctx(desc);
> +
> +	memcpy(out, sctx, sizeof(struct sha1_state));
> +	return 0;
> +}
> +
> +static int sha1_ce_import(struct shash_desc *desc, const void *in)
> +{
> +	struct sha1_ce_state *sctx = shash_desc_ctx(desc);
> +
> +	memcpy(sctx, in, sizeof(struct sha1_state));
> +	sctx->finalize = 0;
> +	return 0;
> +}

Can you use '&sctx->sst' instead of 'sctx' so that we aren't relying on the
'struct sha1_state' being located at the beginning of the struct?

Likewise for SHA-2.

- Eric