linux-kernel - Re: [PATCH v2 4/7] crypto: sun4i-ss: handle BigEndian for cipher

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Message-ID: <CAK8P3a34V16PUoVJjoUOVCik_rdb6vAy=54qRzWdO+aJcwUwsg@mail.gmail.com>
Date:   Wed, 23 Sep 2020 16:00:32 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Corentin Labbe <clabbe@...libre.com>
Cc:     David Miller <davem@...emloft.net>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Maxime Ripard <mripard@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
        <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-sunxi <linux-sunxi@...glegroups.com>,
        "# 3.4.x" <stable@...r.kernel.org>
Subject: Re: [PATCH v2 4/7] crypto: sun4i-ss: handle BigEndian for cipher

On Sun, Sep 20, 2020 at 8:37 PM Corentin Labbe <clabbe@...libre.com> wrote:
>
> Ciphers produce invalid results on BE.
> Key and IV need to be written in LE.
>
> Fixes: 6298e948215f2 ("crypto: sunxi-ss - Add Allwinner Security System crypto accelerator")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Corentin Labbe <clabbe@...libre.com>
> ---
>  drivers/crypto/allwinner/sun4i-ss/sun4i-ss-cipher.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/crypto/allwinner/sun4i-ss/sun4i-ss-cipher.c b/drivers/crypto/allwinner/sun4i-ss/sun4i-ss-cipher.c
> index c6c25204780d..a05889745097 100644
> --- a/drivers/crypto/allwinner/sun4i-ss/sun4i-ss-cipher.c
> +++ b/drivers/crypto/allwinner/sun4i-ss/sun4i-ss-cipher.c
> @@ -52,13 +52,13 @@ static int noinline_for_stack sun4i_ss_opti_poll(struct skcipher_request *areq)
>
>         spin_lock_irqsave(&ss->slock, flags);
>
> -       for (i = 0; i < op->keylen; i += 4)
> -               writel(*(op->key + i / 4), ss->base + SS_KEY0 + i);
> +       for (i = 0; i < op->keylen / 4; i++)
> +               writel(cpu_to_le32(op->key[i]), ss->base + SS_KEY0 + i * 4);

I suspect what you actually want here is writesl() in place of the
loop. This skips the byteswap on big-endian, rather than swapping
each word twice.

The point is that this register seems to act as a FIFO for a byte-stream
rather than a 32-bit fixed-endian register.

     Arnd