Federated identity » History » Revision 6
Revision 5 (Peter Amstutz, 06/19/2017 06:23 PM) → Revision 6/22 (Tom Clegg, 06/19/2017 07:45 PM)
h1. Federated identity A person should be able to create an account and get a token from a single identity provider, and use that token to access private/protected resources on multiple Arvados clusters. Motivating use cases: * A user on cluster B shares a project with a user on cluster A. * A container running on cluster A reads and writes data on cluster B. * A user logged in to Workbench A can search/view/download/upload collections at cluster B. Configuration examples: * An organization has 5 clusters, but only one of them has user accounts and roles in its database. * An on-premise cluster runs containers that use public data stored in the cloud (without mirroring the data locally). h2. Design sketch Each Arvados client must be able to prove to cluster B that it is authorized by cluster A to act on behalf of a user account which is controlled by cluster A. This must not involve giving enough information to cluster B to act on behalf of the user account: for example, the client cannot simply give cluster B its cluster A token for the purpose of doing a canary query. h2. Protocol idea ideas "SRP-6a":https://en.wikipedia.org/wiki/Secure_Remote_Password_protocol "Salted tokens": instead of passing its literal token, the client passes the token UUID and @HMAC(token, "bbbbb")@ when sending a request to cluster B (where "bbbbb" is cluster B's cluster ID / UUID prefix). Cluster B validates the request by passing those two parameters untouched to a "verify request" ("no-op") endpoint at cluster A. * Cluster B figures out cluster A's API endpoint by looking at the "site ID prefix" of the token UUID. * Cluster B can be configured with a lookup table (clusterID→apiHost) to override the implicit {id}.arvadosapi.com * Cluster B can be configured to _only_ use the lookup table, i.e., to never use implicit {id}.arvadosapi.com endpoints (PA) an even simpler approach would be be to contact cluster A to get a scoped token which only allows "GET /users/current" on cluster A but is accepted by cluster B as an [all] token for that user. h2. Adding permissions There are a few permission-granting cases to consider. |grantor|grantee|object|notes| |user on site A|user on site A|object on site A|(existing permission system)| |user on site A|group on site A|object on site A|(existing permission system)| |user on site A|user or group on site A|object on site B|Client creates a link at site B. Site B asks site A whether the grantee user/group is visible to user A.| |user on site A|user or group on site B|object on site B|Client creates a link at site B. Site B asks site A for a list of groups user A can see, then checks whether (possibly via one of those groups) user A can read the grantee user/group according to site B's local database.| |user on site A|user or group on site B|object on site A|Client creates a link at site A. Site A generates a salted token and uses it to ask site B whether user A can read the grantee user/group.| h2. TODO Things to address * how to sync groups * diagrams * mnemonic cluster names / more concrete examples (including who is reachable on the internet) * [how] do you get a list of users/groups users you can share stuff with? * clarify what UUIDs look like (some people have A uuids, some have B uuids)