yahoo-eng-team team mailing list archive

[Tris Emmy Wilson <1924614@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

In user data, if "user" is set to "root" and "ssh_authorized_keys" are
set, any SSH key options are ignored. For example, with the following:

    user: root
    ssh_authorized_keys:
      - cert-authority,principals="globalroot" ssh-ed25519 SomeEd25519Key Global User Issuing CA

...the following ends up in ~root/.ssh/authorized_keys:

    ssh-ed25519 SomeEd25519Key Global User Issuing CA

However, the SSH key options are respected when "user" is not set to
root.

I think, but am not sure, that this is due to an oversight in the
`apply_credentials` method in `cc_ssh.py`. In this snippet:

    if disable_root:                                             
        if not user:                                             
            user = "NONE"                                        
        key_prefix = disable_root_opts.replace('$USER', user)    
        key_prefix = key_prefix.replace('$DISABLE_USER', 'root') 
    else:                                                        
        key_prefix = ''                                          

"key_prefix" being set to the empty string causes
"ssh_util.setup_user_keys" to pass a non-None value to
AuthKeyLineParser.parse, causing it to ignore the options set on the key
in favor of the empty string. I think setting "key_prefix = None" here
may fix the problem but don't know enough about the cloud-init
development process + what the security implications of this might be.

I'm testing in a Proxmox 6 environment using the Debian 10 OpenStack
cloud-init image.

** Affects: cloud-init
     Importance: Undecided
         Status: New

** Attachment added: "cloud-init collect-logs output"
   https://bugs.launchpad.net/bugs/1924614/+attachment/5488515/+files/cloud-init.tar.gz

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https://bugs.launchpad.net/bugs/1924614

Title:
  SSH key options are not respected when user is root

Status in cloud-init:
  New

Bug description:
  In user data, if "user" is set to "root" and "ssh_authorized_keys" are
  set, any SSH key options are ignored. For example, with the following:

      user: root
      ssh_authorized_keys:
        - cert-authority,principals="globalroot" ssh-ed25519 SomeEd25519Key Global User Issuing CA

  ...the following ends up in ~root/.ssh/authorized_keys:

      ssh-ed25519 SomeEd25519Key Global User Issuing CA

  However, the SSH key options are respected when "user" is not set to
  root.

  I think, but am not sure, that this is due to an oversight in the
  `apply_credentials` method in `cc_ssh.py`. In this snippet:

      if disable_root:                                             
          if not user:                                             
              user = "NONE"                                        
          key_prefix = disable_root_opts.replace('$USER', user)    
          key_prefix = key_prefix.replace('$DISABLE_USER', 'root') 
      else:                                                        
          key_prefix = ''                                          

  "key_prefix" being set to the empty string causes
  "ssh_util.setup_user_keys" to pass a non-None value to
  AuthKeyLineParser.parse, causing it to ignore the options set on the
  key in favor of the empty string. I think setting "key_prefix = None"
  here may fix the problem but don't know enough about the cloud-init
  development process + what the security implications of this might be.

  I'm testing in a Proxmox 6 environment using the Debian 10 OpenStack
  cloud-init image.

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