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From:   Ignat Korchagin <ignat@cloudflare.com>
Date:   Wed, 31 Aug 2022 11:00:21 +0100
Message-ID: <CALrw=nECpsJA-Q1ze2-ErQN37hMeWYbyfrWpmzUpsFCq=6R7Ew@mail.gmail.com>
Subject: Re: [PATCH] crypto: akcipher - default implementations for setting
 private/public keys
To:     Herbert Xu <herbert@gondor.apana.org.au>
Cc:     "David S . Miller" <davem@davemloft.net>,
        linux-crypto <linux-crypto@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        kernel-team <kernel-team@cloudflare.com>
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On Wed, Aug 31, 2022 at 9:56 AM Herbert Xu <herbert@gondor.apana.org.au> wrote:
>
> On Tue, Aug 30, 2022 at 11:48:23AM +0100, Ignat Korchagin wrote:
> >
> > I vaguely remember some initial research in quantum-resistant
> > signatures, which used HMAC for "signing" thus don't have any public
> > keys. But it is way beyond my expertise to comment on the practicality
> > and availability of such schemes.
>
> We could always add this again should an algorithm requiring
> it be introduced.
>
> > I'm more concerned here about a buggy "third-party" RSA driver, which
> > may not implement the callback and which gets prioritised by the
> > framework, thus giving the ability to trigger a NULL-ptr dereference
> > from userspace via keyctl(2). I think the Crypto API framework should
> > be a bit more robust to handle such a case, but I also understand that
> > there are a lot of "if"s in this scenario and we can say it is up to
> > crypto driver not to be buggy. Therefore, consider my opinion as not
> > strong and I can post a v2, which does not provide a default stub for
> > set_pub_key, if you prefer.
>
> If you're concerned with buggy algorithms/drivers, we should
> ensure that the self-tests catch this.

So it does currently, because I caught it via testmgr. Will send a v2
without a default set_pub_key.