login: T971 allow quoting in public-keys options

[plett]

Change Summary

Fixes T971 to allow you to specify where a user is allowed to connect from when using an ssh key

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://phabricator.vyos.net/T971

Component(s) name

login

Proposed changes

This uses the " method already used by dhcp_server.py and interfaces-openvpn.py to allow putting " in the options field in authorized_keys.

This is my first PR against VyOS, so please forgive any mistakes I'm making. Thanks to @c-po for guidance via Slack.

This change requires a change to the documentation (actually, options isn't mentioned at all in the login docs). I am happy to add that, but want to make sure this patch is acceptable before doing so.

How to test

vyos@vyos# set system login user paul authentication public-keys paul@thinkpad options from="10.0.0.0/24"
[edit]
vyos@vyos# commit
[edit]
vyos@vyos# sudo cat /home/paul/.ssh/authorized_keys
### Automatically generated by system-login.py ###

from="10.0.0.0/24" ssh-rsa <removed public key> paul@thinkpad

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

[plett]

PR for documenting this is at vyos/vyos-documentation#613