fix(scanner): parsing apt cache policy for nvidia-container-toolkit

[kl-sinclair]

What did you implement:

The repository for NVIDIA Container Toolkit has a different format for apt-cache policy.

$ LANGUAGE=en_US.UTF-8 apt-cache policy wget
wget:
  Installed: 1.20.3-1ubuntu1
  Candidate: 1.20.3-1ubuntu2
  Version table:
     1.20.3-1ubuntu2 500
        500 http://ap-northeast-1.ec2.archive.ubuntu.com/ubuntu focal-updates/main amd64 Packages
 *** 1.20.3-1ubuntu1 500
        500 http://ap-northeast-1.ec2.archive.ubuntu.com/ubuntu focal/main amd64 Packages
        100 /var/lib/dpkg/status

All other packages have 5 fields separated by whitespace.

$ LANGUAGE=en_US.UTF-8 apt-cache policy nvidia-container-toolkit
nvidia-container-toolkit:
  Installed: 1.14.3-1
  Candidate: 1.14.3-1
  Version table:
 *** 1.14.3-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/deb/amd64  Packages
        100 /var/lib/dpkg/status
     1.14.2-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/deb/amd64  Packages
     1.14.1-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/deb/amd64  Packages
     1.14.0-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/deb/amd64  Packages

But the nvidia-container-toolkit has 4 fields, including a blank repo (maybe)

If the nvidia-container-toolkit is installed and updatable for a new version, when you scan with fast-root mode, the following will happen:

# vuls scan

...

ERROR [localhost] Failed to scan installed packages: Failed to fill candidate versions. err: Failed to parse Unknown Format: nvidia-container-toolkit:
  Installed: 1.13.4-1
  Candidate: 1.14.3-1
  Version table:
     1.14.3-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/deb/amd64  Packages
     1.14.2-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/deb/amd64  Packages
     1.14.1-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/deb/amd64  Packages
     1.14.0-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/deb/amd64  Packages
     1.13.5-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/ubuntu18.04/amd64  Packages
 *** 1.13.4-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/ubuntu18.04/amd64  Packages
        100 /var/lib/dpkg/status

...

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Install nvidia-container-toolkit with an older version

$ distribution=$(. /etc/os-release;echo $ID$VERSION_ID) \
      && curl -fsSL https://nvidia.github.io/libnvidia-container/gpgkey | sudo gpg --dearmor -o /usr/share/keyrings/nvidia-container-toolkit-keyring.gpg \
      && curl -s -L https://nvidia.github.io/libnvidia-container/$distribution/libnvidia-container.list | \
            sed 's#deb https://#deb [signed-by=/usr/share/keyrings/nvidia-container-toolkit-keyring.gpg] https://#g' | \
            sudo tee /etc/apt/sources.list.d/nvidia-container-toolkit.list \
      && sudo apt-get update

$ sudo apt-get install -y nvidia-container-toolkit=1.13.4-1

• Check nvidia-container-tookit is updatable

$ LANGUAGE=en_US.UTF-8 apt-cache policy nvidia-container-toolkit
nvidia-container-toolkit:
  Installed: 1.13.4-1
  Candidate: 1.14.3-1
  Version table:
     1.14.3-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/deb/amd64  Packages
     1.14.2-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/deb/amd64  Packages
     1.14.1-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/deb/amd64  Packages
     1.14.0-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/deb/amd64  Packages
     1.13.5-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/ubuntu18.04/amd64  Packages
 *** 1.13.4-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/ubuntu18.04/amd64  Packages
        100 /var/lib/dpkg/status
     1.13.3-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/ubuntu18.04/amd64  Packages
     1.13.2-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/ubuntu18.04/amd64  Packages
     1.13.1-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/ubuntu18.04/amd64  Packages
     1.13.0-1 500
        500 https://nvidia.github.io/libnvidia-container/stable/ubuntu18.04/amd64  Packages

...

• Scan localhost with fast-root mode

# vuls scan

Checklist:

You don't have to satisfy all of the following.

• Write tests
• Write documentation
• Check that there aren't other open pull requests for the same issue/feature
• Format your source code by make fmt
• Pass the test by make test
• Provide verification config / commands
• Enable "Allow edits from maintainers" for this PR
• Update the messages below

Is this ready for review?: YES

Reference

• https://docs.nvidia.com/datacenter/cloud-native/container-toolkit/latest/install-guide.html