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
  • Full security policy can be invoked, but this is painful (based on protected by default & granted manually) & untested within S3 recently
  • We could check for what other functions can access data? Sync. Hard to maintain though.
  • Need a new method: open by default & restricted manually
    • Needs to be a DAL-level method since not all accesses go via S3XRC.
    • Option1: Use an auth_permission table similar to Web2Py 'full' just for tables?
    • Option2: Set within 000_config.py, along with module permissions? (see above example)
      • Means less DAL calls
    • Option3: Have an onaccept which auto-populates the reader_id/writer_id fields in records?
      • Means that no additional auth check at table-level needed
    • 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
  • reader_id checked with a new API function (called from shn_read() & shn_list(), but also available for other functions)
    • 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)
    • Option 1: 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
          (Modified version of current function from models/01_crud.py)
          """
      
          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)
          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)
    • Option 2: 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
  • writer_id checked within a modified shn_has_permission() (called from shn_update(), etc, 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)
        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(table[name].like('%|%d|%' % role)).select()
            # 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?
    • Have a single checkbox for 'Restrict access' which then opens out the 2 fields.

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
  • What if just some fields should be protected?

• 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

• An Admin 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() & shn_accessible_query() to spot this special case &, if no other roles match, then do a lookup in another table (or deployment_settings dict)

• An Admin 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() & shn_accessible_query() to spot this special case &, if no other roles match, then do a lookup in another table (or deployment_settings dict)

• If access to a record is restricted then access to messages relating to that record should also be restricted
  • 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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