PodSecurityPolicy Config fixes to allow runnning in restricted envs.

[skaegi]

Fixes #2966

Changes

1. Moves PSP rule from tekton-pipelines-controller-cluster-access ClusterRole to tekton-pipelines-controller Role. This reduces the scope of where the PSP can be used to prevent privilege escalation
2. Adds PSP rule to tekton-pipelines-webhook to allow the webhook to run when only restricted PSPs are available
3. Adds runAsNonRoot: false to the securityContext of both the controller and webhook deployments to help PSP choose a rule that will let the pods run-as-root

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Release Notes

The tekton-pipelines-controller and tekton-pipelines-controller are now configured to run as a non-root user. To match these reduced requirements, the tekton-pipelines PodSecurityPolicy updates its runAsUser rule to use MustRunAsNonRoot and is further tightened-up to only allow "use" in the tekton-pipelines namespace.

[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ Simon Kaegi (258f472)

[skaegi]

/kind bug

[vdemeester]

/cc @gabemontero

[vdemeester]

@skaegi I think this needs a release-note entry other than NONE though 😛
/hold

[imjasonh]

+1 to release noting

[dlorenc]

Yeah this one could probably use a release note. I can't think if a good way to word it, but in case people see weird permission issues pop up it would be good to have a release note to help them track it back to this change.

[dlorenc]

The build error should be fixed now

/test pull-tekton-pipeline-build-tests

[skaegi]

updated release notes and squashed for enhanced beauty

[vdemeester]

/hold cancel

[gabemontero]

per the ask in AP WG today @skaegi I took another look ... more questions came up than anything else

a) first the easy one ... so far all the changes so far look fine to me, and the needs for them that you cited seem valid to me
b) now, are we interested in how more restricted the policy could be made and still have the various tekton scenarios work?
c) or have you already gone through that exercise @skaegi and this is where you landed?

If the answer to b) is "yes" and c) is "no", I might have some additional suggestions, but at first blush I'm hesitant to go down that path. But if that was your intent when you asked me to look, let me know and we can discuss.

[dlorenc]

/approve

This looks good to me! Thanks!

[tekton-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dlorenc

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[vdemeester]

/lgtm