Changes/dropingOfCertPemFile

dropping Of cert.pem file

This is a proposed Change for Fedora Linux.
This document represents a proposed Change. As part of the Changes process, proposals are publicly announced in order to receive community feedback. This proposal will only be implemented if approved by the Fedora Engineering Steering Committee.

Summary

In order to increase the performance of OpenSSL by default using directory-hash format we need to drop the /etc/pki/tls/cert.pem file to prevent it from being loaded by default. This also includes the certificate bundles in /etc/pki/tls/certs/ folder(ca-certificates.crt, ca-bundle.crt).

Owner

• Name: František Krenželok
• Email: fkrenzel@redhat.com

Current status

• Targeted release: Fedora Linux 42
• Last updated: 2024-12-24
• Initial Announcement
• Re-announcement
• Discussion thread
• FESCo issue: #3293
• Tracker bug: <will be assigned by the Wrangler>
• Release notes tracker: <will be assigned by the Wrangler>

Detailed Description

In order to improve the loading time of OpenSSL, a directory-hash support was added to ca-certificates. In order for OpenSSL to use the directory-hash format by default we need to stop it from trying to load /etc/pki/tls/cert.pem by deleting it. This also applies to the certificate bundles in /etc/pki/tls/certs/ folder(ca-certificates.crt, ca-bundle.crt).

Feedback

(a) Changing the OpenSSL configuration directory (OPENSSLDIR)

Automated tools often rely on the output of openssl version -d to infer locations such as <OPENSSLDIR>/openssl.cnf as the configuration file. Changing OPENSSLDIR risks breaking these assumptions and complicating integrations.

A possible solution could be changing the directory to something like /usr/lib/openssl/ and shipping a symlink, e.g., /usr/lib/openssl/openssl.cnf -> /etc/pki/tls/openssl.cnf. However, this is less than ideal.

(b) Patching the OpenSSL source code

This approach involves patching OpenSSL to use directories outside of the OPENSSLDIR/certs default for the root certificates.

Although it avoids relocating the configuration file. It introduces a downstream patch that would need to be maintained indefinitely(There are already loads of patches and the maintainers really dislike this idea). Such a patch would also be unexpected behavior for users accustomed to upstream defaults.

This was partly discussed here: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/NNVFZMRDXNJN6OJE2ZUJ3NWPHUW6EB2F/

Note: Option (a) is gravely discouraged. Option (b) could be implemented instead, but it still has drawbacks, including potentially unforeseen ones.

Benefit to Fedora

Applications using OpenSSL(possibly other libraries as well) will benefit from much faster initialization of OpenSSL.

Scope

• Other developers:

Any package loading the root certificates from any of the following bundles:

/etc/pki/tls/cert.pem

/etc/pki/tls/certs/ca-certificates.crt

/etc/pki/tls/ca-bundle.crt

needs to preferably use the defaults of the library or if they must, use the /etc/pki/ca-trust/extracted/pem/tls-ca-bundle.pem file instead.

• Release engineering: #Releng issue number
• Policies and guidelines: N/A (not needed for this Change)
• Trademark approval: N/A (not needed for this Change)
• Alignment with the Fedora Strategy: neither does nor doesn't

Upgrade/compatibility impact

Once this change is integrated, the packages/software using any of the following files /etc/pki/tls/cert.pem /etc/pki/tls/certs/ca-certificates.crt /etc/pki/tls/ca-bundle.crt as a root certificate bundle file might encounter connectivity issues.

How To Test

Target behavior: OpenSSL initialization takes less time when the file isn't present compared to it being there.

1. The following will create a symlink for testing after the change has been integrated(i.e. the .../tls/cert.pem file is missing)

ln -s /etc/pki/ca-trust/extracted/pem/tls-ca-bundle.pem /etc/pki/tls/cert.pem

2. Test the time of OpenSSL initialization or a package using it with and without the aforementioned symlink. (If there is no difference for package then it is most likely due to OpenSSL not being configured to search for certs in default location)

User Experience

Packages using a OpenSSL will have faster initialization time.

Dependencies

Any package using /etc/pki/tls/cert.pem,/etc/pki/tls/certs/ca-certificates.crt or /etc/pki/tls/ca-bundle.crt file are affected. It is required that the maintainers change this so that user experience is not compromised.

Contingency Plan

• Contingency mechanism: We will postpone the change if majority or critical package owners will be unable to make appropriate changes.
• Contingency deadline: before end of beta freeze(2025-02-18).
• Blocks release? The feature doesn't block release.

Documentation

The change is documented as a part of ca-certificates package changelog.

Release Notes

The /etc/pki/tls/cert.pem certificate file has been Removed.