From: Eric Biggers <ebiggers3@gmail.com>
To: "Stephan Müller" <smueller@chronox.de>
Cc: keyrings@vger.kernel.org, linux-crypto@vger.kernel.org,
David Howells <dhowells@redhat.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
mathew.j.martineau@linux.intel.com,
Eric Biggers <ebiggers@google.com>
Subject: Re: [PATCH 3/5] KEYS: DH: don't feed uninitialized result memory into KDF
Date: Thu, 20 Apr 2017 20:44:48 -0700 [thread overview]
Message-ID: <20170421034448.GA626@zzz> (raw)
In-Reply-To: <2707352.sSpDZZo8GT@tauon.chronox.de>
Hi Stephan,
On Thu, Apr 20, 2017 at 08:38:30PM +0200, Stephan Müller wrote:
> >
> > By the way: do we really need this in the kernel at all, given that it's
> > just doing some math on data which userspace has access to?
>
> It is the question about how we want the keys subsystem to operate. The DH
> shared secret shall not be used as a key. But the DH operation is part of the
> key subsystem. If there is never a case where the result of the DH operation
> is used in the kernel, then the KDF can be removed and my patches could be
> reverted. However, in this case, the entire DH business could be questioned as
> this can easily be done in user space as well.
>
Well, who exactly is asking for Diffie-Hellman in the kernel at all? If it can
be done in userspace then it should be done there. Having it in the kernel
means having yet another API that's callable by unprivileged users and needs to
be audited for security vulnerabilities. Just because the kernel can support
doing hashes or has an arbitrary-precision arithmetic library or whatever
doesn't mean it's the right place to do random crypto stuff.
- Eric
next prev parent reply other threads:[~2017-04-21 3:44 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-20 5:46 [PATCH 0/5] KEYS: fixes for new keyctl_dh_compute() KDF extension Eric Biggers
2017-04-20 5:46 ` [PATCH 1/5] KEYS: DH: forbid using digest_null as the KDF hash Eric Biggers
2017-04-20 5:46 ` [PATCH 2/5] KEYS: DH: don't feed uninitialized "otherinfo" into KDF Eric Biggers
2017-04-20 5:46 ` [PATCH 3/5] KEYS: DH: don't feed uninitialized result memory " Eric Biggers
2017-04-20 13:27 ` Stephan Müller
2017-04-20 17:46 ` Eric Biggers
2017-04-20 18:38 ` Stephan Müller
2017-04-21 3:44 ` Eric Biggers [this message]
2017-04-27 15:15 ` David Howells
2017-04-28 5:26 ` Eric Biggers
2017-04-20 5:46 ` [PATCH 4/5] KEYS: DH: ensure the KDF counter is properly aligned Eric Biggers
2017-04-20 5:46 ` [PATCH 5/5] KEYS: DH: add __user annotations to keyctl_kdf_params Eric Biggers
2017-04-28 15:53 ` [PATCH 0/5] KEYS: fixes for new keyctl_dh_compute() KDF extension David Howells
2017-04-28 15:56 ` Stephan Müller
2017-05-01 14:52 ` Stephan Müller
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