Attachments Authorization Model¶
This document describes the authorization model used for attachments and associated endpoints.
Actions¶
The following actions are defined for attachments:
AttachmentCreateAttachmentReadAttachmentUpdateAttachmentDelete
Permissions¶
Permissions are granted cumulatively to users based on their group association. The following permission levels are granted to users:
Unauthenticated¶
An unauthenticated user may read attachments only if the attachment is public. Unauthenticated users do not have write access.
Authenticated¶
An authenticated user may read attachments if the attachment is public or if they are a member of the attachment's ownerGroup or one of the accessGroups.
Authenticated users do not have write access by default.
ATTACHMENT_GROUPS¶
If a user is part of a group listed in configuration as part of ATTACHMENT_GROUPS, in addition to the permissions granted to authenticated users, they are permitted to create, update and delete attachments if the ownerGroup matches one of the user's currentGroups. Importantly, it is not necessary that ownerGroup be in ATTACHMENT_GROUPS.
This permission can be extended to all authenticated users by providing the token #all under ATTACHMENT_GROUPS in configuration.
ATTACHMENT_PRIVILEGED_GROUPS¶
If a user is part of a group listed in configuration as part of ATTACHMENT_PRIVILEGED_GROUPS, in addition to the permissions granted to authenticated users, they are permitted to create attachments for any ownerGroup.
They may update and delete attachments if the ownerGroup matches one of the user's currentGroups.
ADMIN_GROUPS¶
If a user is part of a group listed in configuration as part of ADMIN_GROUPS, they have unrestricted create, read, update and delete access to all attachments.
DELETE_GROUPS¶
If a user is part of a group listed in configuration as part of DELETE_GROUPS, they have unrestricted delete access to all attachments in the database.
Permission Matrix¶
Table of the different permission classes defined in casl. For all special permission groups, the full list includes the relevant permissions passed on from generic authenticated user permissions.
| Operation | Unauthenticated | Authenticated | ATTACHMENT_GROUPS |
ATTACHMENT_PRIVILEGED_GROUPS |
ADMIN_GROUPS |
DELETE_GROUPS |
|---|---|---|---|---|---|---|
AttachmentCreate |
- | - | owner | any | any | - |
AttachmentRead |
public | public/owner/access | public/owner/access | public/owner/access | any | public/owner/access |
AttachmentUpdate |
- | - | owner | owner | any | - |
AttachmentDelete |
- | - | owner | owner | any | any |
Legend:
- public: attachment's isPublished field must be true
- owner: attachment's ownerGroup must match one of the user's currentGroups
- access: one of the attachment's accessGroups must match one of the user's currentGroups
- any: unrestricted access
Implementation Notes¶
The definition is implemented in the casl module under /src/casl/abilities/attachments.ability.ts and accessible elsewhere via CaslAbilityFactory.attachmentAccess. This one function is used to build one casl ability for endpoint and instance authorization: When a user receives permission for an action under some instance-level condition, they should implicitly pass endpoint authorization.
The AttachmentAbility module in /src/casl/abilities/attachments.ability.ts is written in such a way that permissions are cumulative. In case multiple rules apply, casl will chain them in a logical or, ultimately giving precedence to the broadest applicable rule. The special permission groups are sorted roughly in ascending order of privilege level.
In case there are expectations of mutual exclusivity for certain special groups (not the case for attachments currently), additional rules using the cannot ability expression can be added after all can rules have been defined. For an example, see the jobs subsystem authorization docs.