Re: [PATCH v2] Documentation: crypto: add info about "fips=" boot option

Eric Biggers
2021-03-30T05:30:30Z

On Mon, Mar 29, 2021 at 10:06:51PM -0700, Randy Dunlap wrote:
> Having just seen a report of using "fips=1" on the kernel command line,
> I could not find it documented anywhere, so add some help for it.
>
> Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
> Cc: Dexuan Cui <decui@microsoft.com>
> Cc: linux-crypto@vger.kernel.org
> Cc: Eric Biggers <ebiggers@kernel.org>
> Cc: Herbert Xu <herbert@gondor.apana.org.au>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: linux-doc@vger.kernel.org
> ---
> Updates/corrections welcome.
>
> v2: drop comment that "fips_enabled can cause some tests to be skipped".
>
> Documentation/admin-guide/kernel-parameters.txt | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> --- linux-next-20210329.orig/Documentation/admin-guide/kernel-parameters.txt
> +++ linux-next-20210329/Documentation/admin-guide/kernel-parameters.txt
> @@ -1370,6 +1370,20 @@
> See Documentation/admin-guide/sysctl/net.rst for
> fb_tunnels_only_for_init_ns
>
> + fips= Format: { 0 | 1}
> + Use to disable (0) or enable (1) FIPS mode.
> + If enabled, any process that is waiting on the
> + 'fips_fail_notif_chain' will be notified of fips
> + failures.
> + This setting can also be modified via sysctl at
> + /proc/sysctl/crypto/fips_enabled, i.e.,
> + crypto.fips_enabled.
> + If fips_enabled = 1 and a test fails, it will cause a
> + kernel panic.
> + If fips_enabled = 1, RSA test requires a key size of
> + 2K or larger.
> + It can also effect which ECC curve is used.

This doesn't really explain why anyone would want to give this option.
What high-level thing is this option meant to be accomplishing?
That's what the documentation should explain.

- Eric