netdev - Re: [PATCH net-next v2 3/3] sctp: Convert cookie authentication to use HMAC-SHA256

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Message-ID: <CADvbK_csEoZhA9vnGnYbfV90omFqZ6dX+V3eVmWP7qCOqWDAKw@mail.gmail.com>
Date: Fri, 15 Aug 2025 17:19:27 -0400
From: Xin Long <lucien.xin@...il.com>
To: Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: Eric Biggers <ebiggers@...nel.org>, linux-sctp@...r.kernel.org, netdev@...r.kernel.org, 
	Marcelo Ricardo Leitner <marcelo.leitner@...il.com>, linux-crypto@...r.kernel.org
Subject: Re: [PATCH net-next v2 3/3] sctp: Convert cookie authentication to
 use HMAC-SHA256

On Fri, Aug 15, 2025 at 3:09 PM Jakub Kicinski <kuba@...nel.org> wrote:
>
> On Tue, 12 Aug 2025 21:01:21 -0700 Eric Biggers wrote:
> > +     if (net->sctp.cookie_auth_enable)
> > +             tbl.data = (char *)"sha256";
> > +     else
> > +             tbl.data = (char *)"none";
> > +     tbl.maxlen = strlen(tbl.data);
> > +     return proc_dostring(&tbl, 0, buffer, lenp, ppos);
>
> I wonder if someone out there expects to read back what they wrote,
> but let us find out.
I feel it's a bit weird to have:

# sysctl net.sctp.cookie_hmac_alg="md5"
net.sctp.cookie_hmac_alg = md5
# sysctl net.sctp.cookie_hmac_alg
net.sctp.cookie_hmac_alg = sha256

This patch deprecates md5 and sha1 use there.
So generally, for situations like this, should we also issue a
warning, or just fail it?

Paolo, what do you think?

>
> It'd be great to get an ack / review from SCTP maintainers, otherwise
> we'll apply by Monday..
Other than that, LGTM.
Sorry for the late reply, I was running some SCTP-auth related tests
against the patchset.