GPG Keys

Clients use GPG keys to check the authenticity of software packages before they are installed. Only trusted software can be installed on clients.

In most cases, you do not need to adjust the GPG settings to be able to install software on your clients.

RPM packages can be signed directly, while Debian based systems sign only the metadata and use a chain of checksums to secure the packages. Most RPM based systems use signed metadata in addition to signed packages.

1. Trust GPG Keys on Clients

Operating systems either trust their own GPG keys directly or at least ship them installed with the minimal system. But third party packages signed by a different GPG key need manual handling. The clients can be successfully bootstrapped without the GPG key being trusted. However, you cannot install new client tool packages or update them until the keys are trusted.

Salt clients use now GPG key information entered for a software channel to manage the trusted keys. When a software channel with GPG key information is assigned to a client, the key gets trusted as soon as the channel is refreshed or the first package gets installed from this channel.

The GPG key URL which is set of a software channel must exist. In case it is a file URL, the GPG key file must be deployed on the client before the software channel is used.

The GPG keys for the Client Tools Channels of Red Hat based clients are deployed on the client into /etc/pki/rpm-gpg/ and can be referenced with file URLs. Same is the case with the GPG keys of Expanded Support clients. Only in case a software channel is assigned to the client they will be imported and trusted by the system.

Because Debian based systems sign only metadata, there is typically no need to specify extra keys for single channels. If a user configures an own GPG key to sign the metadata as described in "Use Your Own GPG Key" in administration:repo-metadata.adoc the deployment and trust of that key is executed automatically.

1.1. User defined GPG keys

Users can define their own GPG keys to be deployed to the client.

By providing some pillar data and providing the GPG key files in the Salt filesystem, they are automatically deployed to the client.

These keys are deployed into /etc/pki/rpm-gpg/ on RPM based operating systems and to /usr/share/keyrings/ on Debian systems:

Define the pillar key [literalcustom_gpgkeys for the client you want to deploy the key to and list the names of the key file.

cat /etc/pillar/mypillar.sls
custom_gpgkeys:
  - my_first_gpg.key
  - my_second_gpgkey.gpg

Additionally in the Salt filesystem create a directory named gpg and store there the GPG key files with the name specified in the custom_gpgkeys pillar data.

ls -la /etc/salt/gpg/
/etc/salt/gpg/my_first_gpg.key
/etc/salt/gpg/my_second_gpgkey.gpg

The keys are now deployed to the client at /etc/pki/rpm-gpg/my_first_gpg.key and /etc/pki/rpm-gpg/my_second_gpgkey.gpg.

The last step is to add the URL to the GPG key URL field of the software channel. Navigate to Software  Manage  Channels and select the channel you want to modify. Add to GPG key URL the value file:///etc/pki/rpm-gpg/my_first_gpg.key.

1.2. GPG Keys in Bootstrap Scripts

Procedure: Trusting GPG Keys on Clients Using a Bootstrap Script
  1. On the Uyuni Server, at the command prompt, check the contents of the /srv/www/htdocs/pub/ directory. This directory contains all available public keys. Take a note of the key that applies to the channel assigned to the client you are registering.

  2. Open the relevant bootstrap script, locate the ORG_GPG_KEY= parameter and add the required key. For example:

    uyuni-gpg-pubkey-0d20833e.key

    You do not need to delete any previously stored keys.

Trusting a GPG key is important for security on clients. It is the task of the admin to decide which keys are needed and can be trusted. Because a software channel cannot be used when the GPG key is not trusted, the decision of assigning a channel to a client depends on the decision of trusting the key.