Binaries built with opensslcrypto experiment can sometimes fallback to gocrypto, for historical algorithms

[xnox]

Below uses MD5, but the same logic also applies to DES, 3DES, RC4.
Leaving future algorithms out of scope for this bug report (i.e. Ed25519).

• Openssl crypto on non-fips hosts usually supports MD5.
• Some may build openssl without MD5 (no-md5), though no known distributions do this yet
• There is a variety of openssl FIPS modules
• Some of them do not contain MD5 with property fips=yes (All 3.0.0+ fips modules)
• Some of them advertise MD5 as available, but then it is blocked at runtime (1.1.1 from Mainer 2.0, Old Ubuntu).
• In some of the above scenarios fallback to gocrypto MD5 is indifferent, useful, or undesired.

I would like to argue that fallback to gocrypto is undesired on any fips hosts, for historical algorithms that are being removed.

• For openssl FIPS 1.1.1 and lower, currently MD5 gets blocked at runtime because openssl module advertises MD5 as available; and toolchain/binaries are using it at runtime; which then fails at runtime.
• For openssl FIPS 3.0.0 and higher, currently MD5 is advertised as not available at all, and the same binary that previously was blocked from using MD5 - now silently fallsback to gocrypto code, potentially in violation of approved only policy of the system configured openssl.
• This lead to anomaly that “echo Hello | openssl md5” fails, and go binary that does the same also fails with old FIPS modules, but magically calculates MD5 with modern FIPS modules.
• This is particularly undesirable for very old algorithms, which has now become obsolete, historical and prohibited. And even marked as unapproved, in the existing Active 140-2 certificates.

Design proposal:

• Add an additional indicator in the Boring module to indicate if the backend is detected to be in FIPS or non-fips mode.
• In the legacy algorithms not only check for when boring is enabled, and a given algorithm is available, but also if the module is in fips mode or not
• As fips mode should not be bypassed without raising a service indicator

Previously filed as a PR at #1327

[xnox]

Pondering if this is exact opposite of golang-fips/openssl@2cf9b4c