Kubectl: Crafted CN fields in CSRs can create confusing results in kubectl output

[raesene]

What happened:

Data passed in the CN and O fields of a CSR submitted to the Kubernetes API server will be represented by kubectl in a way that could cause confusion for the administrator. It is possible to craft a CN field that modifies the appearance of the CSR when displayed with kubectl describe

As an example, the CSR below, has additional text in the CN field which when viewed with kubectl describe looks like this.

From the screenshot there may be some confusion as to whether the O field in the certificate is "usergroup" , or "system:masters"

apiVersion: certificates.k8s.io/v1beta1
kind: CertificateSigningRequest
metadata:
  name: user2
spec:
  request: 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

Using openssl it's possible to see the modified CN field more clearly

What you expected to happen:

Kubectl should escape any characters in the CSR object before displaying them to the user, to avoid any confusion about the structure of the CSR.

How to reproduce it (as minimally and precisely as possible):

Apply the CSR above to a Kubernetes cluster, then issue the command kubectl describe csr user2

Environment:

• Kubernetes 1.18.2

[liggitt]

quoting the fields with %q would be reasonable

[enj]

The code is here in case anyone wants to take a look.

[enj]

/good-first-issue

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[vinu2003]

Hey @raesene i can take a look at this as part of my learning task.
/assign @vinu2003

[vinu2003]

Hey @raesene , would it be nice to change the CommonName to CN and O for usergroup in kubectl describe output ?
Any thoughts on this @liggitt @enj

[eddiezane]

/priority backlog

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@fejta-bot: Closing this issue.

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