From: Eric Biggers <ebiggers@kernel.org>
To: Thomas Huth <thuth@redhat.com>
Cc: Ilya Dryomov <idryomov@gmail.com>,
Alex Markuze <amarkuze@redhat.com>,
Viacheslav Dubeyko <slava@dubeyko.com>,
Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>,
ceph-devel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] libceph: Re-establish the FIPS keylength check in the Ceph code
Date: Fri, 21 Aug 2026 19:36:36 +0000 [thread overview]
Message-ID: <20260821193636.GB3141245@google.com> (raw)
In-Reply-To: <20260821175312.GA3141245@google.com>
On Fri, Aug 21, 2026 at 05:53:15PM +0000, Eric Biggers wrote:
> Do Ceph session keys shorter than 128 bits even actually occur in
> practice? It seems that the Ceph authenticated modes support only
> AES-based cipher suites, where the minimum valid session key length is
> 128 bits.
>
> I wonder if the client should just reject session_key_len < 16
> regardless of fips_enabled.
It looks like this is theoretically possible only when CEPH_AUTH_CEPHX
is being used but the session key uses CEPH_CRYPTO_NONE, which seems
insecure and contradictory, and likely not ever used by the server. I
suspect the ceph client should just reject that combination outright
(and also session_key_len < 16 as defense-in-depth). It is up to the
ceph folks who are the experts here, but if there are unnecessary
footguns like this, they should just be fixed for everyone.
- Eric
prev parent reply other threads:[~2026-08-21 19:36 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-21 14:43 [PATCH] libceph: Re-establish the FIPS keylength check in the Ceph code Thomas Huth
2026-08-21 17:53 ` Eric Biggers
2026-08-21 19:36 ` Eric Biggers [this message]
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