Determine whether OpenSSL needs to be configured (FIPs, SHA1 s… …ignature)

[stefanberger]

Get the list of enabled 'RuntimeAlgorithms' from libtpms and determine
whether any of these enabled algorithms is disabled in OpenSSL due to FIPS
mode. If FIPS mode on the host is enabled then disabled FIPS mode in
OpenSSL so that the TPM 2 can function properly.

The following algorithms are disabled when OpenSSL is in FIPS mode:

• camellia
• rsaes
• tdes
• ECC keys <224 bits
• RSA signing with SHA1 and key of any size

Per openssl-ciphers man page it should be possible to disable the following
algorithms use by cipher-suites:

• AES128, AES256, AES
• CAMELLIA128, CAMELLIA256, CAMELLIA
• 3DES
• SHA1, SHA, SHA256, SHA384
• CBC

WIP: It's not clear at what API level these are disabled. I have not been able
to use !SHA256 to disabled SHA256.

[stefanberger]

@elmarco @berrange These are for now the unchanged remainders of the original profiles PR. I believe swtpm still needs to check whether FIPs mode is enabled in OpenSSL but maybe display an error message if it is and algorithms are not functioning and exit, OR allow to disable FIPS mode in the OpenSSL instance if the user passed a command line option.

[stefanberger]

It seems there are different ways we could disable the enforcement of disabled algorithms on a host:

• OPENSSL_no_config() : do not read any configuration file; very last resort
• EVP_default_properties_enable_fips(NULL, 0): this seems to enable a few algorithms disabled by FIPS mode; /etc/crypto-policies/back-ends/opensslcnf.config not changed between fips and non-fips mode

My current thinking is to

1. check for FIPS mode enabled and
2. if it is enabled test candidate algorithms to be disabled by FIPS mode
3. then disable FIPS mode if necessary and
4. then test the same candidate algorithms again and possibly more
5. and exit with error if any algorithm fails

This is a test program:

#include <openssl/evp.h>
#include <openssl/conf.h>

int main(void)
{
//    OPENSSL_no_config();
//    EVP_default_properties_enable_fips(NULL, 1);

    printf("AES-128-CFB: %d\n", EVP_CIPHER_fetch(NULL, "AES-128-CFB", NULL));
    printf("AES-256-CFB: %d\n", EVP_CIPHER_fetch(NULL, "AES-256-CFB", NULL));
    printf("CAMELLIA-128-CFB: %d\n", EVP_CIPHER_fetch(NULL, "CAMELLIA-128-CFB", NULL));
    printf("CAMELLIA-256-CFB: %d\n", EVP_CIPHER_fetch(NULL, "CAMELLIA-256-CFB", NULL));
    printf("DES-EDE3-CFB: %d\n", EVP_CIPHER_fetch(NULL, "DES-EDE3-CFB", NULL));

    EVP_default_properties_enable_fips(NULL, 0);

    printf("AES-128-CFB: %d\n", EVP_CIPHER_fetch(NULL, "AES-128-CFB", NULL));
    printf("CAMELLIA-128-CFB: %d\n", EVP_CIPHER_fetch(NULL, "CAMELLIA-128-CFB", NULL));
    printf("CAMELLIA-256-CFB: %d\n", EVP_CIPHER_fetch(NULL, "CAMELLIA-256-CFB", NULL));
    printf("DES-EDE3-CFB: %d\n", EVP_CIPHER_fetch(NULL, "DES-EDE3-CFB", NULL));
}

On a FIPS-enabled FC-40 host this prints:

AES-128-CFB: 1005757168
AES-256-CFB: 1005756496
CAMELLIA-128-CFB: 0
CAMELLIA-256-CFB: 0
DES-EDE3-CFB: 0
AES-128-CFB: 1005653632
CAMELLIA-128-CFB: 1005727792
CAMELLIA-256-CFB: 1005725840
DES-EDE3-CFB: 1005741520

Per this man page here https://docs.openssl.org/3.0/man1/openssl-ciphers/#cipher-strings it seems to be necessary to test availability of the following algorithms:

• sha1, sha256, sha384
• aes-128, aes-256, aes-192
• camellia-128, camellia-192, camellia-256
• 3des
• cbc
  (subject to verification)

Thought "fips=yes" does have some other meanings not covered via the cipherstrings.