BluePrint for Authorization

User Stories

• A Developer needs to be able to restrict access to a Module:
  • s3.modules in 01_modules.py
  • Add Controller check as well as menu check.
  • Configure permissions in 000_config.py instead of 01_modules.py?
    • Change deployment_settings.modules from a list of strings to a Storage()

      # Need to define Roles in dict for visibility by modules before inserted into DB
      deployment_settings.auth.roles = {
          1 : "Administrator",
          2 : "Authenticated",
          ....
          6 : "AdvancedJS",
      }
      
      deployment_settings_modules = Storage(
          gis = Storage(
              name_nice = "Mapping",
              description = "Situation Awareness & Geospatial Analysis",
              readable = None,    # All Users (inc Anonymous) can see this module in the default menu & access the controller
              writable = None,    # All Authenticated users can edit resources which aren't specially protected
              module_type = 2,    # Used to locate the module in the default menu
              resources = Storage(
                  apikey = {
                          read : 1,     # This resource is only visible to Administrators
                      },
                  layer_js = {
                          create : deployment_settings.auth.roles["AdvancedJS"],    # This resource requires the 'AdvancedJS' role to create (or admin)
                          delete : deployment_settings.auth.roles["AdvancedJS"],    # This resource requires the 'AdvancedJS' role to delete (or admin)
                          update : deployment_settings.auth.roles["AdvancedJS"],    # This resource requires the 'AdvancedJS' role to update (or admin)
                      }
              ),
          ),
          ...
      )
      

• A Developer needs to be able to restrict access to a Function:
  • Decorator function : @auth.requires_membership("Administrator")
    • doesn't support OR (we could easily write our own function to do this, though)

• A Developer needs to be able to restrict access to a Resource:
  • REST controller can be blocked via a Decorator
    • we'd need to patch other functions, such as sync, which would be hard to maintain
  • Full security policy (native web2py) can be invoked, but this is painful (based on protected by default & granted manually) & untested within S3 recently
  • Need a new method: open by default & restricted manually
    • Option1: Use an auth_permission table similar to Web2Py 'full' but just for tables & with group_id as multiple=True
    • Option2: Set within 000_config.py, along with module permissions? (see above example)
      • Means less DAL calls
    • Option3: Have an onvalidation which auto-populates the reader_id/writer_id fields in records?
      • Means that no additional auth check at table-level needed
      • If done at validation time then it means that no extra DAL calls are done when creating resources (just extra field(s) within the 1 DAL call)
    • Once new solution in-place:
      • remove security_policy from s3_setting table & session (00_utils.py)
      • modify shn_action_buttons() in 00_utils.py

• A Developer needs to be able to restrict access to a Record:
  • Add 2 reusable multiple=True fields to each table which needs this: reader_id & writer_id combined as permissions_id
    • Full backward compatibility since they default to None
  • For List views modify shn_accessible_query() (called from shn_list() & shn_search())
    • combine with the deleted==True check?
      • makes it easier to then replace that check with an 'inactive' field which is a date instead of a boolean, so that records can be set to expire (as well as giving us easy access to know when a record was deleted)
    • Preferred Option: Do the check alongside deleted as part of a big JOIN

      def shn_accessible_query(table):
          """
          Return a filter of those records which are readable by the currently logged-in user
          - deleted records are filtered
          - records to which they don't have permissions are filtered
          """
      
          deleted = (table.deleted == None)
      
          try:
              user_id = auth.user.id
              _memberships = db.auth_membership
              memberships = db(_memberships.user_id == user_id).select(_memberships.group_id, cache=(cache.ram, 60))
          except:
              memberships = None
          
          roles = []
          for membership in memberships:
              roles.append(membership.group_id)
      
          if 1 in roles:
              # Admins see all data
              query = deleted
          else:
             # Fields with no restriction
             accessible = (table.reader_id == None)
             for role in roles:
                 #accessible = accessible & (table.reader_id == str(role)) & (table.reader_id.like('%d|%' % role)) & (table.reader_id.like('%|%d|%' % role)) & (table.reader_id.like('%|%d' % role))
                 accessible = accessible & (table.reader_id.like('%|%d|%' % role))
             query = deleted & accessible
          return query
      
      def user_function():
          ...
          table = db[tablename]
          available = shn_accessible_query(table)
          query = available & query
          ...
      

      • Advantages:
        • Combines the deleted into single API call
        • Single JOIN for optimal DB performance (Assumption needs testing)
    • Alternate Option: Do the check in Python after the initial query has returned
      • Advantage: Might have better performance than complex DB string?
      • Disadvantage: More records pulled from DB than necessary

• For single records modify shn_has_permission() (called from shn_create(), shn_delete(), shn_read() & shn_update(), but also available for other functions)

  def shn_has_permission(name, tablename, record_id = 0):
      """
          S3 framework function to define whether a user can access a record in manner "name"
      """
  
      try:
          user_id = auth.user.id
          _memberships = db.auth_membership
          memberships = db(_memberships.user_id == user_id).select(_memberships.group_id, cache=(cache.ram, 60))
      except:
          memberships = None
      
      roles = []
      for membership in memberships:
          roles.append(membership.group_id)
  
      # Check if table is restricted
      table = db[tablename]
      if 1 in roles:
          # Admins see all tables
          authorised = True
      else:   
          # Option 1
          #restriction = db(db.auth_permission.table_name == tablename).select(db.auth_permission.group_id, limitby=(0, 1), cache=(cache.ram, 60)).first().group_id
          #if restriction:
          #   authorised = False
          #   restrictions = re.split("\|", restriction)[1:-1]
              # Assume we generally have fewer restrictions than roles
          #   for restriction in restrictions:
          #        if restriction in roles:
          #            authorised = True
          #else:
          #    authorised = True 
          # Option 2
          module, resource = tablename.split("_", 1)
          try:
              restriction = deployment_settings_modules["module"].resources["resource"]["name"]
          except:
              restriction = None
          
          if restriction:
              if restriction in roles:
                  authorised = True
              else:
                  authorised = False
          else:
              # No restriction
              authorised = True
          # Option 3
          # - not necessary!
  
      if record_id and authorised:
          # Check if record is deleted
          record = db(table.id == record_id).select(table.deleted, table.reader_id, table.writer_id, limitby=(0, 1)).first()
          if record.deleted:
              authorised = False
          elif 1 in roles:
              authorised = True
          else:
              if name == "read":
                  if not table.reader_id:
                      authorised = True
                  else:
                      authorised = False
                      restrictions = re.split("\|", table.reader_id)[1:-1]
                      # Assume we generally have fewer restrictions than roles
                      for restriction in restrictions:
                          if restriction in roles:
                              authorised = True
                      
              elif name in ["delete", "update"]:
                  if not table.writer_id:
                      authorised = True
                  else:
                      authorised = False
                      restrictions = re.split("\|", table.writer_id)[1:-1]
                      # Assume we generally have fewer restrictions than roles
                      for restriction in restrictions:
                          if restriction in roles:
                              authorised = True
  
              else:
                  # Something went wrong
                  session.error = str(T("Invalid mode sent to")) + " shn_has_permission(): " + name
                  redirect(URL(r=request, f="index"))
  
  return authorised
  

  • Disadvantage: Slow

• UI to manage the fields.
  • We expect relatively few groups per instance, so can use the checkboxes widget?
    • can filter out some groups?
  • Have a single checkbox for 'Restrict access' which then opens out the 2 fields.

• A Developer needs to be able to restrict access to a Field:
  • In model (for access by all controllers, such as sync):

    try:
        user_id = auth.user.id
        _memberships = db.auth_membership
        memberships = db(_memberships.user_id == user_id).select(_memberships.group_id, cache=(cache.ram, 60))
    except:
        memberships = None
    
    roles = []
    for membership in memberships:
        roles.append(membership.group_id)
    
    if 1 not in roles and myrole not in roles:
        table.field.readable = False
    

    • NB If doing this then the roles checks inside shn_has_permission() & shn_accessible_fields() should be modified to read this global value

Specific Examples

• A Person's Contacts shouldn't be visible by default.
  • Authenticated is OK
    • Simply add the Authenticated group (2) to the table (or records in the table if using Option 3)
    • This requires all authenticated users to be added to the 'Authenticated' group

• A Person's Subscriptions shouldn't be visible by default.
  • Admin or themselves is OK
    • Option A: restore the web2py default of adding 1 group per user!
      • In models/00_settings.py: auth.settings.create_user_groups = True
      • Check using auth.user_group(auth.user.id)
      • Filter these out of our views?
    • Option B: use the link from subscription to person & do manual check somewhere
      • tbc
  • We may want to allow people to be subscribed to things by others.
    • This would need a 'Subscriber Admin' role
      • We could give this role to all registered users by default if we Hook into the registration onaccept
        • Currently this requires modifying shn_register() in modules/sahana.py

• A Developer should be able to restrict access to records to just those within a certain GIS location (e.g. Country or Region)
  • Add a special role 'Geographic' which can be added to writer_id (& maybe reader_id although less use case for this)
    • Patch shn_has_permission() & maybe shn_accessible_query() to spot this special case &, if no other roles match, then do a lookup in another table (or deployment_settings dict)

• A Developer should be able to restrict access to records to just those within a certain organisation (or the Focal Point for the organisation)
  • Add a special role 'Organisation' which can be added to writer_id (& maybe reader_id although less use case for this)
    • Patch shn_has_permission() & maybe shn_accessible_query() to spot this special case &, if no other roles match, then do a lookup in another table (or deployment_settings dict)

• A Developer should be able to restrict access to records to just those which the person created
  • Add a special role 'Creator' which can be added to writer_id (& maybe reader_id although less use case for this)
    • Patch shn_has_permission() & maybe shn_accessible_query() to spot this special case &, if no other roles match, then do a check between auth.user.id & table.created_by

• If access to a record is restricted then access to messages relating to that record should also be restricted
  • i.e. block subscription
  • unless routed somewhere visible as well!
  • onaccept on message routing (tagging) to check if the only tags are on restricted resources...if they are then restrict the message too.

• Some tables should be writable by unauthenticated users (writable=|0|)
  • Need special handling for this in shn_create/shn_update?
    • Might need to differentiate the 2 (can deposit new but not edit existing)
  • Might want to be have new records by unauthenticated users not be visible in lists until an admin has approved them

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