linux-kernel - Re: [PATCH v2 04/13] RISC-V: crypto: add Zvkned accelerated AES implementation

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Date:   Mon, 27 Nov 2023 19:56:30 -0800
From:   Eric Biggers <ebiggers@...nel.org>
To:     Jerry Shih <jerry.shih@...ive.com>
Cc:     paul.walmsley@...ive.com, palmer@...belt.com,
        aou@...s.berkeley.edu, herbert@...dor.apana.org.au,
        davem@...emloft.net, conor.dooley@...rochip.com, ardb@...nel.org,
        heiko@...ech.de, phoebe.chen@...ive.com, hongrong.hsu@...ive.com,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-crypto@...r.kernel.org
Subject: Re: [PATCH v2 04/13] RISC-V: crypto: add Zvkned accelerated AES
 implementation

On Mon, Nov 27, 2023 at 03:06:54PM +0800, Jerry Shih wrote:
> +int riscv64_aes_setkey(struct crypto_aes_ctx *ctx, const u8 *key,
> +		       unsigned int keylen)
> +{
> +	int ret;
> +
> +	ret = aes_check_keylen(keylen);
> +	if (ret < 0)
> +		return -EINVAL;
> +
> +	/*
> +	 * The RISC-V AES vector crypto key expanding doesn't support AES-192.
> +	 * Use the generic software key expanding for that case.
> +	 */
> +	if ((keylen == 16 || keylen == 32) && crypto_simd_usable()) {
> +		/*
> +		 * All zvkned-based functions use encryption expanding keys for both
> +		 * encryption and decryption.
> +		 */
> +		kernel_vector_begin();
> +		rv64i_zvkned_set_encrypt_key(key, keylen, ctx);
> +		kernel_vector_end();
> +	} else {
> +		ret = aes_expandkey(ctx, key, keylen);
> +	}

rv64i_zvkned_set_encrypt_key() does not initialize crypto_aes_ctx::key_dec.
So, decryption results will be incorrect if !crypto_simd_usable() later.

> +static int aes_setkey(struct crypto_tfm *tfm, const u8 *key,
> +		      unsigned int keylen)

It's best to avoid generic-sounding function names like this that could collide
with functions in crypto/ or lib/crypto/.  A better name for this function, for
example, would be aes_setkey_zvkned().

> diff --git a/arch/riscv/crypto/aes-riscv64-zvkned.pl b/arch/riscv/crypto/aes-riscv64-zvkned.pl
> new file mode 100644
> index 000000000000..303e82d9f6f0
> --- /dev/null
> +++ b/arch/riscv/crypto/aes-riscv64-zvkned.pl
[...]
> +L_enc_128:
[...]
> +L_enc_192:
[...]
> +L_enc_256:

There's some severe source code duplication going on in the AES assembly, with
the three AES variants having separate source code.  You can just leave this
as-is since this is what was merged into OpenSSL and we are borrowing that for
now, but I do expect that we'll want to clean this up later.

- Eric