Re: [PATCH v3] net/sctp: Make sha1 as default algorithm if fips is enabled

From: Xin Long <lucien.xin@gmail.com>
To: Simon Horman <simon.horman@corigine.com>
Cc: Ashwin Dayanand Kamat <kashwindayan@vmware.com>,
	Vlad Yasevich <vyasevich@gmail.com>,
	 Neil Horman <nhorman@tuxdriver.com>,
	Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>,
	 "David S . Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	 Jakub Kicinski <kuba@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>,
	linux-sctp@vger.kernel.org,  netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, amakhalov@vmware.com,
	 vsirnapalli@vmware.com, akaher@vmware.com, tkundu@vmware.com,
	 keerthanak@vmware.com
Subject: Re: [PATCH v3] net/sctp: Make sha1 as default algorithm if fips is enabled
Date: Fri, 2 Jun 2023 19:16:09 -0400	[thread overview]
Message-ID: <CADvbK_fCPPHto4XjPeTJPJ9NTXoJGgO7jjEcy1Bq3nQSFAzR9A@mail.gmail.com> (raw)
In-Reply-To: <ZHoHfcMgYqO3l7Np@corigine.com>

On Fri, Jun 2, 2023 at 11:15 AM Simon Horman <simon.horman@corigine.com> wrote:
>
> + Xin Long
>
> On Thu, Jun 01, 2023 at 11:47:54PM +0530, Ashwin Dayanand Kamat wrote:
> > MD5 is not FIPS compliant. But still md5 was used as the
> > default algorithm for sctp if fips was enabled.
> > Due to this, listen() system call in ltp tests was
> > failing for sctp in fips environment, with below error message.
> >
> > [ 6397.892677] sctp: failed to load transform for md5: -2
> >
> > Fix is to not assign md5 as default algorithm for sctp
> > if fips_enabled is true. Instead make sha1 as default algorithm.
> > The issue fixes ltp testcase failure "cve-2018-5803 sctp_big_chunk"
Hi, Ashwin,

I have the same question as Paolo about "this patch gets fips compliance
_disabling_ the encryption", is it from any standard?

If not,  can't you fix the ltp testcase for fips environment by sysctl?
or set 'CONFIG_SCTP_DEFAULT_COOKIE_HMAC_SHA1=y' instead in config.

Sorry if I don't understand this well. You're trying to avoid SCTP code
calling crypto_alloc_shash(MD5), right? What about other places
where it may also do it in kernel? (where ltp just doesn't cover)

I don't think it makes sense to let SCTP have some code reply on
FIPS only to make ltp testcase happy, while we can actually fix it
in ltp by "sysctl".

Thanks.

> >
> > Signed-off-by: Ashwin Dayanand Kamat <kashwindayan@vmware.com>
> > ---
> > v3:
> > * Resolved hunk failures.
> > * Changed the ratelimited notice to be more meaningful.
> > * Used ternary condition for if/else condtion.
> > v2:
> > * The listener can still fail if fips mode is enabled after
> >   that the netns is initialized.
> > * Fixed this in sctp_listen_start() as suggested by
> >   Paolo Abeni <pabeni@redhat.com>
>
> FWIIW, this seems reasonable to me.
>
> Reviewed-by: Simon Horman <simon.horman@corigine.com>