STIG Script Incorrectly Modifies openssl.cnf Causing SSL Handshaking Errors

Summary

scripts/xccdf_org.ssgproject.content_rule_configure_openssl_crypto_policy.sh is incorrect and is causing non-deterministic SSL handshake errors with FIPS enabled containers.

That script references /etc/crypto-policies/back-ends/openssl.config, but it should be referring to /etc/crypto-policies/back-ends/opensslcnf.config. See http://static.open-scap.org/ssg-guides/ssg-rhel8-guide-ospp.html#xccdf_org.ssgproject.content_rule_configure_openssl_crypto_policy

Steps to reproduce

Our Kubernetes nodes for USAF Weather have FIPS enabled at the kernel level, as such, our containers are also enforcing FIPS.

$ cat /proc/sys/crypto/fips_enabled
1

Enable FIPS in the Dockerfile:

(I realize there is a redhat/ubi/ubi8:8.5-fips, but all of the Python containers, which is what we are using, use ubi8:8.5. Regardless, this issue also affects ubi8:8.5-fips)

FROM registry1.dso.mil/ironbank/redhat/ubi/ubi8:8.5

RUN fips-mode-setup --enable

What is the current bug behavior?

OpenSSL is offering non-FIPS compliant ciphers during the ClientHello portion of the SSL Handshake:

$ openssl ciphers -s -v -tls1_3
TLS_AES_256_GCM_SHA384  TLSv1.3 Kx=any      Au=any  Enc=AESGCM(256) Mac=AEAD
TLS_CHACHA20_POLY1305_SHA256 TLSv1.3 Kx=any      Au=any  Enc=CHACHA20/POLY1305(256) Mac=AEAD
TLS_AES_128_GCM_SHA256  TLSv1.3 Kx=any      Au=any  Enc=AESGCM(128) Mac=AEAD

As a result, some servers pick a FIPS compliant cipher in response, in which case the SSL handshake succeeds, while others pick a non-compliant cipher (TLS_CHACHA20_POLY1305_SHA256), resulting in curl: (35) error:0607B0C8:digital envelope routines:EVP_CipherInit_ex:disabled for FIPS.

What is the expected correct behavior?

It should only offer valid ciphers that it can accept. Such as docker.io/rhel/ubi8:8.5 does:

FROM redhat/ubi8:8.5

RUN fips-mode-setup --enable && dnf -y install openssl

$ openssl ciphers -s -v -tls1_3
TLS_AES_256_GCM_SHA384  TLSv1.3 Kx=any      Au=any  Enc=AESGCM(256) Mac=AEAD
TLS_AES_128_GCM_SHA256  TLSv1.3 Kx=any      Au=any  Enc=AESGCM(128) Mac=AEAD
TLS_AES_128_CCM_SHA256  TLSv1.3 Kx=any      Au=any  Enc=AESCCM(128) Mac=AEAD

Relevant logs and/or screenshots

Looking at /etc/pki/tls/openssl.cnf, I found the following discrepancies:

Official RHEL UBI 8.5:

[ crypto_policy ]

.include /etc/crypto-policies/back-ends/opensslcnf.config

IronBank UBI 8.5 :

[ crypto_policy ]

.include /etc/crypto-policies/back-ends/openssl.config


.include /etc/crypto-policies/back-ends/opensslcnf.config

IronBank UBI 8.5-fips:

[ crypto_policy ]

.include /etc/crypto-policies/back-ends/openssl.config


.include /etc/crypto-policies/back-ends/openssl.config


.include /etc/crypto-policies/back-ends/opensslcnf.config

IronBank UBI 8.5 Minimal:

[ crypto_policy ]

.include /etc/crypto-policies/back-ends/openssl.config


.include /etc/crypto-policies/back-ends/opensslcnf.config

Please note that this affects ubi8, ubi8-fips, and ubi8-minimal. And with ubi8-fips, since it is based on ubi8, it is running the script a second time, causing an additional erroneous entry.

If I remove the incorrect includes, OpenSSL works correctly.