linux-kernel - Re: [PATCH bpf-next v7 3/4] bpf: Add signature verification kfuncs

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Message-ID: <ow6qiz7tusazk4gb4it3qvilwygk7qroifuwbtruao4rww4ddl@orh4uw5dz3st>
Date: Wed, 4 Feb 2026 09:47:24 -0500
From: Daniel Hodges <daniel@...ielhodges.dev>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc: Daniel Hodges <git@...ielhodges.dev>, bpf <bpf@...r.kernel.org>, 
	Alexei Starovoitov <ast@...nel.org>, Andrii Nakryiko <andrii@...nel.org>, 
	Daniel Borkmann <daniel@...earbox.net>, Vadim Fedorenko <vadim.fedorenko@...ux.dev>, 
	Song Liu <song@...nel.org>, Mykyta Yatsenko <yatsenko@...a.com>, 
	Martin KaFai Lau <martin.lau@...ux.dev>, Eduard <eddyz87@...il.com>, Hao Luo <haoluo@...gle.com>, 
	Jiri Olsa <jolsa@...nel.org>, John Fastabend <john.fastabend@...il.com>, 
	KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>, 
	Yonghong Song <yonghong.song@...ux.dev>, Herbert Xu <herbert@...dor.apana.org.au>, 
	"David S. Miller" <davem@...emloft.net>, Linux Crypto Mailing List <linux-crypto@...r.kernel.org>, 
	LKML <linux-kernel@...r.kernel.org>, 
	"open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@...r.kernel.org>
Subject: Re: [PATCH bpf-next v7 3/4] bpf: Add signature verification kfuncs

On Tue, Feb 03, 2026 at 10:44:05AM -0800, Alexei Starovoitov wrote:
> On Mon, Feb 2, 2026 at 6:48 AM Daniel Hodges <git@...ielhodges.dev> wrote:
> >
> > Add a 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.
> >
> > The module provides:
> >    - alloc_tfm/free_tfm for crypto_sig transform lifecycle
> >    - has_algo to check algorithm availability
> >    - setkey for public key configuration
> >    - verify for signature verification
> >    - get_flags for crypto API flags
> >
> > Introduce bpf_sig_verify, bpf_sig_keysize, bpf_sig_digestsize,
> > and bpf_sig_maxsize kfuncs enabling BPF programs to verify digital
> > signatures using the kernel's crypto infrastructure.
> >
> > Add enum bpf_crypto_type_id for runtime type checking to ensure
> > operations are performed on the correct crypto context type. The enum
> > values are assigned to all crypto type modules (skcipher, hash, sig).
> >
> > The verify kfunc takes a crypto context (initialized with the sig
> > type and appropriate algorithm like "ecdsa-nist-p256"), a message
> > digest, and a signature. These kfuncs support any signature algorithm
> > registered with the crypto subsystem (e.g., ECDSA, RSA).
> >
> > Signed-off-by: Daniel Hodges <git@...ielhodges.dev>
> > ---
> >  MAINTAINERS                |   1 +
> >  crypto/Makefile            |   3 +
> >  crypto/bpf_crypto_sig.c    |  89 ++++++++++++++++++++++++++++
> >  include/linux/bpf_crypto.h |   4 ++
> >  kernel/bpf/crypto.c        | 117 +++++++++++++++++++++++++++++++++++++
> >  5 files changed, 214 insertions(+)
> >  create mode 100644 crypto/bpf_crypto_sig.c
> 
> Other than the issue spotted by AI the patches look fine,
> but we need Ack from crypto maintainers.

Sounds good, I'll wait to hear from them before sending anything else.