Re: [PATCH bpf-next v4 2/6] crypto: Add BPF signature algorithm type registration module

[Vadim Fedorenko <vadim.fedorenko@linux.dev>]

On 05/01/2026 17:37, Daniel Hodges wrote:
> Add a new bpf_crypto_sig module that registers signature verification
> algorithms with the BPF crypto type system. This enables signature
> operations (like ECDSA) to use the unified bpf_crypto_ctx structure
> instead of requiring separate context types.
> 
> The module provides:
> - alloc_tfm/free_tfm for crypto_sig transform lifecycle
> - has_algo to check algorithm availability
> - get_flags for crypto API flags
> 
> This allows ECDSA and other signature verification operations to
> integrate with the existing BPF crypto infrastructure.
> 
> Signed-off-by: Daniel Hodges <git@danielhodges.dev>

[...]

> +static int bpf_crypto_sig_setkey(void *tfm, const u8 *key, unsigned int keylen)
> +{
> +	return crypto_sig_set_pubkey(tfm, key, keylen);
> +}

That effectively means that signature verification only is provided for
BPF programs? Do we plan to extend API to sign a buffer?

> +
> +static const struct bpf_crypto_type bpf_crypto_sig_type = {
> +	.alloc_tfm	= bpf_crypto_sig_alloc_tfm,
> +	.free_tfm	= bpf_crypto_sig_free_tfm,
> +	.has_algo	= bpf_crypto_sig_has_algo,
> +	.get_flags	= bpf_crypto_sig_get_flags,
> +	.setkey		= bpf_crypto_sig_setkey,
> +	.owner		= THIS_MODULE,
> +	.name		= "sig",
> +};

I think we have to introduce verify() callback here.