netdev - Re: [PATCH bpf-next v7 1/3] bpf: make common crypto API for TC/XDP programs

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Date: Sun, 3 Dec 2023 10:57:48 +0000
From: Simon Horman <horms@...nel.org>
To: Vadim Fedorenko <vadfed@...a.com>
Cc: Vadim Fedorenko <vadim.fedorenko@...ux.dev>,
	Jakub Kicinski <kuba@...nel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Andrii Nakryiko <andrii@...nel.org>,
	Alexei Starovoitov <ast@...nel.org>,
	Mykola Lysenko <mykolal@...com>,
	Herbert Xu <herbert@...dor.apana.org.au>, netdev@...r.kernel.org,
	linux-crypto@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH bpf-next v7 1/3] bpf: make common crypto API for TC/XDP
 programs

On Fri, Dec 01, 2023 at 05:06:02PM -0800, Vadim Fedorenko wrote:
> Add crypto API support to BPF to be able to decrypt or encrypt packets
> in TC/XDP BPF programs. Special care should be taken for initialization
> part of crypto algo because crypto alloc) doesn't work with preemtion
> disabled, it can be run only in sleepable BPF program. Also async crypto
> is not supported because of the very same issue - TC/XDP BPF programs
> are not sleepable.
> 
> Signed-off-by: Vadim Fedorenko <vadfed@...a.com>

...

> +/**
> + * bpf_crypto_ctx_create() - Create a mutable BPF crypto context.
> + *
> + * Allocates a crypto context that can be used, acquired, and released by
> + * a BPF program. The crypto context returned by this function must either
> + * be embedded in a map as a kptr, or freed with bpf_crypto_ctx_release().
> + * As crypto API functions use GFP_KERNEL allocations, this function can
> + * only be used in sleepable BPF programs.
> + *
> + * bpf_crypto_ctx_create() allocates memory for crypto context.
> + * It may return NULL if no memory is available.
> + * @type__str: pointer to string representation of crypto type.
> + * @algo__str: pointer to string representation of algorithm.
> + * @pkey:      bpf_dynptr which holds cipher key to do crypto.

Hi Vadim,

a minor nit from my side: something about @authsize should go here.

> + * @err:       integer to store error code when NULL is returned
> + */
> +__bpf_kfunc struct bpf_crypto_ctx *
> +bpf_crypto_ctx_create(const char *type__str, const char *algo__str,
> +		      const struct bpf_dynptr_kern *pkey,
> +		      unsigned int authsize, int *err)

...