netdev - Re: [PATCH bpf-next v8 1/3] bpf: make common crypto API for TC/XDP programs

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Message-ID: <3d2d5f4e-c554-4648-bcec-839d83585123@linux.dev>
Date: Wed, 24 Jan 2024 17:10:36 -0800
From: Martin KaFai Lau <martin.lau@...ux.dev>
To: Vadim Fedorenko <vadfed@...a.com>,
 Vadim Fedorenko <vadim.fedorenko@...ux.dev>
Cc: netdev@...r.kernel.org, linux-crypto@...r.kernel.org,
 bpf@...r.kernel.org, Victor Stewart <v@...etag.social>,
 Jakub Kicinski <kuba@...nel.org>, Andrii Nakryiko <andrii@...nel.org>,
 Alexei Starovoitov <ast@...nel.org>, Mykola Lysenko <mykolal@...com>,
 Herbert Xu <herbert@...dor.apana.org.au>
Subject: Re: [PATCH bpf-next v8 1/3] bpf: make common crypto API for TC/XDP
 programs

On 1/15/24 2:08 PM, Vadim Fedorenko wrote:
> +static int bpf_crypto_crypt(const struct bpf_crypto_ctx *ctx,
> +			    const struct bpf_dynptr_kern *src,
> +			    struct bpf_dynptr_kern *dst,
> +			    const struct bpf_dynptr_kern *siv,
> +			    bool decrypt)
> +{
> +	u32 src_len, dst_len, siv_len;
> +	const u8 *psrc;
> +	u8 *pdst, *piv;
> +	int err;
> +
> +	if (ctx->type->get_flags(ctx->tfm) & CRYPTO_TFM_NEED_KEY)

nit. Does the indirect call get_flags() return different values?
Should it be rejected earlier, e.g. in bpf_crypto_ctx_create()?

> +		return -EINVAL;
> +
> +	if (__bpf_dynptr_is_rdonly(dst))
> +		return -EINVAL;
> +
> +	siv_len = __bpf_dynptr_size(siv);
> +	src_len = __bpf_dynptr_size(src);
> +	dst_len = __bpf_dynptr_size(dst);
> +	if (!src_len || !dst_len)
> +		return -EINVAL;
> +
> +	if (siv_len != (ctx->type->ivsize(ctx->tfm) + ctx->type->statesize(ctx->tfm)))

Same here, two indirect calls per en/decrypt kfunc call. Does the return value 
change?

> +		return -EINVAL;
> +
> +	psrc = __bpf_dynptr_data(src, src_len);
> +	if (!psrc)
> +		return -EINVAL;
> +	pdst = __bpf_dynptr_data_rw(dst, dst_len);
> +	if (!pdst)
> +		return -EINVAL;
> +
> +	piv = siv_len ? __bpf_dynptr_data_rw(siv, siv_len) : NULL;
> +	if (siv_len && !piv)
> +		return -EINVAL;
> +
> +	err = decrypt ? ctx->type->decrypt(ctx->tfm, psrc, pdst, src_len, piv)
> +		      : ctx->type->encrypt(ctx->tfm, psrc, pdst, src_len, piv);
> +
> +	return err;
> +}