Hi, > On 5. Jul 2024, at 12:38, Daniel P. Berrangé <berra...@redhat.com> wrote: > > I've (re-)discovered that this change is going to impact on swtpm that is > used with QEMU to provide a virtual TPM to guests. > > The TPM2 specification has fully crypto agility, however, the sha1 > algorithm is one of the few that is declared mandatory to implement. > Though it is documented as deprecated by the spec, we need to provide > it to be compliant.
Please start addressing this with whoever maintains the TPM specification. SHA-1 already doesn’t work in FIPS mode, so anything that breaks with this change is already broken in FIPS mode, and the deprecation of SHA-1 will only continue to cause more and more problems. See also https://fedoraproject.org/wiki/SHA1SignaturesGuidance#Cryptographic_immobility_or_outdated_standards. > The 'runcp' command is really particularly nice as a solution though. > Using that in a non-interactive scenario will require modifying the > software that launches swtpm to wrap its execution. Or we have to > replace the swtpm binary with a shell script that invokes the real > binary indirectly, which isn't especially nice either, as wrapper > shell scripts often require then changing the selinux policy to > allow their use. An alternative is to run swtpm with OPENSSL_CONF in the environment pointing to an alternative openssl configuration file that re-enables SHA-1. You could maintain this configuration file together with swtpm. > The change proposal talks about an API being added to openssl to > allow this to be changed programmatically, which is really what > I would like to see, so that swtpm can just request SHA1, as this > has the lowest impact. The upstream work on this is stalled, both due to my lack of time and upstream’s requests to change it fundamentally twice after I had working implementations. I wouldn’t rely on this showing up any time soon. I still want to eventually finish it, but until that happens and then gets released in a new OpenSSL version, this doesn’t exist. > Until that exists, however, I'm inclined > to just set OPENSSL_ENABLE_SHA1_SIGNATURES in swtpm startup, > despite the warnings not to do this. As announced, we’re going to break that without regard for whether you used it, and it won’t make a difference in FIPS mode. You should really use a separate openssl configuration file using OPENSSL_CONF instead, and start a discussion to get the TPM standard updated. -- Clemens Lang RHEL Crypto Team Red Hat -- _______________________________________________ devel mailing list -- devel@lists.fedoraproject.org To unsubscribe send an email to devel-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org Do not reply to spam, report it: https://pagure.io/fedora-infrastructure/new_issue
