XS Blueprints:Lease and update server

Lease and activation services are a key role of the XS. They are key enablers at the school and in the warehouse where the XOs are prepared for deployment.

Scenarios

• Tama is a field technician, he's visiting a rural school without internet. He has a new OS build to install on the existing laptops and 20 new laptops to hand out with serial numbers that the existing XS doesn't have leases for.
• Lee is a field technician. He is deploying an XS to a school that did not have one earlier - so the XOs had very long leases, which now need to be shortened.
• Teacher Catalina travelled to town and got leases and an OS image on a USB stick. The XS at his school is slow -- she wonders whether anything is happening with the USB stick.
• Jocinta is a NOC sysadmin and wants to get all the XSs out there with the new leases for a XO shipment that is being handed out, new blacklist (a few machines have been misplaced) and updated XO OS images. She has to prepare an update for the internet-connected XSs, and a usb img for the non-connected ones.
• Ludmilla and Jim are technicians at the warehouse in Wellingtonia-- they have 5K XOs to activate and update. They want to use a temporary machine - perhaps one of the XOs even - as lease and update server.
• In Zoolandia it is the first day of school after summer holidays -- kids are returning to school and those who haven't visited school in the holidays have their XOs locked. The wireless signal in the Zoolandia schools is unencrypted.
• First day at school in Oz is a bit more complicated -- wireless network signal is WPA encrypted or perhaps the wireless antenna is broken, flaky, saturated. Teacher wants to prepare an "unlocker" usb stick to pass around.

• See also the requirements definition Feature_roadmap#Activation_lease_security

Implementation Notes

XO side

• OFW: delegation support is a nice-to-have (but unlikely to happen soon).

Leases/OATC checks against XS in 2 places: initrd and olpc-update-query.

Initrd:

• Trivial proto port 191
• 'STOLEN' response is taken "unwrapped", but is transient
• Fix: hardcoded XS url in init, differs from activate.py -> service announcement (if we have dns at this stage!)

olpc-update-query:

• Fix: hardcoded XS url -> svc announcement
• Review/dev: frequency is weird, can we simplify it?
• Dev: checks only for update
  • add 'lease' support (dsd patches)
  • add 'stolen' support (&& touch /security/.private/stolen)
• Test/review: Bitfrost delegated keys support seems to be complete - test!

Also:

• Review/dev: do we need an "I don't know you" response from the server?
• Fix/dev: Large JSON files problem in initrd. We need a stream parser for this :-)

XS side

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Test plans and user walkthrough

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TODOs and future work

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