fix(credential-provider): check acr pattern to avoid spoofing

[mainred]

What type of PR is this?

/kind bug

What this PR does / why we need it:

There's a potential spoofing when the image
".azurecr.io.example.com/ubuntu2:latest when sent to the credential provider plugin, it will fetch credential from .azurecr.io unexpectedly
Currently it's not possible considering kubelet will not call credential provider plugin since the ".azurecr.io.example.com/ubuntu2:latest" does not match the matchImages defined below.
Also the credential provider plugin as a binary is installed on k8s node, is currently only called by kubelet if there's no manual operation.

apiVersion: kubelet.config.k8s.io/v1
kind: CredentialProviderConfig
providers:
  - name: acr-credential-provider
    matchImages:
      - "*.azurecr.io"
      - "*.azurecr.cn"
      - "*.azurecr.de"
      - "*.azurecr.us"
    defaultCacheDuration: "10m" // follow in-tree setting
    apiVersion: credentialprovider.kubelet.k8s.io/v1
    args:
      - /etc/kubernetes/azure.json

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

fix(credential-provider): check acr pattern to avoid spoofing

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @mainred. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[mainred]

@bahe-msft I did not use the function you suggested https://github.com/kubernetes/kubernetes/blob/2bda5dd8c794d933145938affca30f012986e8fa/pkg/credentialprovider/keyring.go#L184-L194 because when it comes down credential provider from kubelet, it's a determined acr image, so we just need to follow acr pattern to do the match and validation

[MartinForReal]

/ok-to-test

[feiskyer]

Looks good, let's wait for e2e validation results

[mainred]

fortunately, use acr with repo will raise authorization failure because kubelet will pull this kind of image from docker hub

Failed to pull image "qingchuanhao.azurecr.io": failed to pull and unpack image "docker.io/library/qingchuanhao.azurecr.io:latest": failed to resolve reference "docker.io/library/qingchuanhao.azurecr.io:latest": pull access denied, repository does not exist or may require authorization: server message: insufficient_scope: authorization failed

[mainred]

  containers:
  - name: container
    image: qingchuanhao.azurecr.io

[mainred]

For assert.Equal, expected variable comes before actual variable.
https://github.com/stretchr/testify/blob/master/assert/assertions.go#L460