link libkrb5 with openssl

[Nikos Mavrogiannopoulos]

In Ubuntu we provide a cryptographic core based on a small set of packages that we FIPS certify [0]. Applications and libraries should not bundle their own crypto code but should use the cryptographic core to benefit from the certification, but also importantly to reduce bugs due to small cryptographic libraries that that are not studied as much as more popular counterparts. This bug is to change libkrb5 to use the openssl crypto code instead of bundling its own on the next ubuntu release.

[0]. https://ubuntu.com/security/fips

[Dimitri John Ledkov (xnox)]

krb5 (1.13~alpha1+dfsg-1) experimental; urgency=low

  [ Benjamin Kaduk ]
  * New upstream prerelease:
    - Add support for accessing KDCs via an https proxy using the MS-KKDCP
      protocol, using a plugin provided by the new krb5-k5tls package, which
      uses openssl for the TLS implementation. The openssl-using code is
      confined to a separate, runtime-loadable, plugin module, in a separate
      package, to ameliorate concerns about GPL code that links libkrb5 running
      into issues with the openssl license. The Kerberos license is both
    GPL and OpenSSL compatible. There might be an issue if an application
    was GPL licensed and someone used the OpenSSL plugin with that
    application. Even that is probably fine provided that no one
    distributes a combination that tends to encourage such usage. There's
    an existing krb5-pkinit plugin that also links to OpenSSL, but at time
    of integration into Debian no GPLed applications in the archive called
    APIs that would cause that plugin to be loaded.

The above concerns are still valid, and given that currently OpenSSL is neither GPLv2 or GPLv3 compatible doing this may not be feasible immediately.

The licensing choices will have to be re-evaluated again, once OpenSSL v3 is the default OpenSSL implementation in the archive, which is GPLv3 compatible.

[Andreas Hasenack (ahasenack)]

Do we even know for sure this krb5-k5tls is enough for fips compliance, and that it replaces *all* crypto code in kerberos with openssl calls?

[Dimitri John Ledkov (xnox)]

> Do we even know for sure this krb5-k5tls is enough for fips compliance, and that it replaces *all* crypto code in kerberos with openssl calls?

No it does not. But intention is to make the over the network communications with TLS to be FIPS-TLS compliant which is cheaper to certify when reusing a certified TLS component library.

[Nikos Mavrogiannopoulos (nmavrogiannopoulos)]

For 22.04 we should switch to openssl 3.0 for cryptography for the whole.