X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/f8743ac8fa1ed9dc8c7c4f7a23803ffe8721cfa6..3aaefcb3c76ff470b475d950398d01255e87712a:/services/api/app/models/link.rb

diff --git a/services/api/app/models/link.rb b/services/api/app/models/link.rb
index af3918551e..83043a56d1 100644
--- a/services/api/app/models/link.rb
+++ b/services/api/app/models/link.rb
@@ -1,15 +1,23 @@
+# Copyright (C) The Arvados Authors. All rights reserved.
+#
+# SPDX-License-Identifier: AGPL-3.0
+
 class Link < ArvadosModel
   include HasUuid
   include KindAndEtag
   include CommonApiTemplate
-  serialize :properties, Hash
-  before_create :permission_to_attach_to_objects
-  before_update :permission_to_attach_to_objects
-  after_update :maybe_invalidate_permissions_cache
-  after_create :maybe_invalidate_permissions_cache
-  after_destroy :maybe_invalidate_permissions_cache
-  attr_accessor :head_kind, :tail_kind
-  validate :name_link_has_valid_name
+
+  # Posgresql JSONB columns should NOT be declared as serialized, Rails 5
+  # already know how to properly treat them.
+  attribute :properties, :jsonbHash, default: {}
+
+  validate :name_links_are_obsolete
+  validate :permission_to_attach_to_objects
+  before_update :restrict_alter_permissions
+  after_update :call_update_permissions
+  after_create :call_update_permissions
+  before_destroy :clear_permissions
+  after_destroy :check_permissions
 
   api_accessible :user, extend: :common do |t|
     t.add :tail_uuid
@@ -21,11 +29,6 @@ class Link < ArvadosModel
     t.add :properties
   end
 
-  def properties
-    @properties ||= Hash.new
-    super
-  end
-
   def head_kind
     if k = ArvadosModel::resource_class_for_uuid(head_uuid)
       k.kind
@@ -40,6 +43,28 @@ class Link < ArvadosModel
 
   protected
 
+  def check_readable_uuid attr, attr_value
+    if attr == 'tail_uuid' &&
+       !attr_value.nil? &&
+       self.link_class == 'permission' &&
+       attr_value[0..4] != Rails.configuration.ClusterID &&
+       ApiClientAuthorization.remote_host(uuid_prefix: attr_value[0..4]) &&
+       ArvadosModel::resource_class_for_uuid(attr_value) == User
+      # Permission link tail is a remote user (the user permissions
+      # are being granted to), so bypass the standard check that a
+      # referenced object uuid is readable by current user.
+      #
+      # We could do a call to the remote cluster to check if the user
+      # in tail_uuid exists.  This would detect copy-and-paste errors,
+      # but add another way for the request to fail, and I don't think
+      # it would improve security.  It doesn't seem to be worth the
+      # complexity tradeoff.
+      true
+    else
+      super
+    end
+  end
+
   def permission_to_attach_to_objects
     # Anonymous users cannot write links
     return false if !current_user
@@ -47,49 +72,111 @@ class Link < ArvadosModel
     # All users can write links that don't affect permissions
     return true if self.link_class != 'permission'
 
+    if PERM_LEVEL[self.name].nil?
+      errors.add(:name, "is invalid permission, must be one of 'can_read', 'can_write', 'can_manage', 'can_login'")
+      return false
+    end
+
+    rsc_class = ArvadosModel::resource_class_for_uuid tail_uuid
+    if rsc_class == Group
+      tail_obj = Group.find_by_uuid(tail_uuid)
+      if tail_obj.nil?
+        errors.add(:tail_uuid, "does not exist")
+        return false
+      end
+      if tail_obj.group_class != "role"
+        errors.add(:tail_uuid, "must be a user or role, was group with group_class #{tail_obj.group_class}")
+        return false
+      end
+    elsif rsc_class != User
+      errors.add(:tail_uuid, "must be a user or role")
+      return false
+    end
+
     # Administrators can grant permissions
     return true if current_user.is_admin
 
-    # All users can grant permissions on objects they own
-    head_obj = self.class.
-      resource_class_for_uuid(self.head_uuid).
-      where('uuid=?',head_uuid).
-      first
-    if head_obj
-      return true if head_obj.owner_uuid == current_user.uuid
+    head_obj = ArvadosModel.find_by_uuid(head_uuid)
+
+    if head_obj.nil?
+      errors.add(:head_uuid, "does not exist")
+      return false
+    end
+
+    # No permission links can be pointed to past collection versions
+    if head_obj.is_a?(Collection) && head_obj.current_version_uuid != head_uuid
+      errors.add(:head_uuid, "cannot point to a past version of a collection")
+      return false
     end
 
-    # Users with "can_grant" permission on an object can grant
-    # permissions on that object
-    has_grant_permission = self.class.
-      where('link_class=? AND name=? AND tail_uuid=? AND head_uuid=?',
-            'permission', 'can_grant', current_user.uuid, self.head_uuid).
-      count > 0
-    return true if has_grant_permission
+    # All users can grant permissions on objects they own or can manage
+    return true if current_user.can?(manage: head_obj)
 
     # Default = deny.
     false
   end
 
-  def maybe_invalidate_permissions_cache
+  def restrict_alter_permissions
+    return true if self.link_class != 'permission' && self.link_class_was != 'permission'
+
+    return true if current_user.andand.uuid == system_user.uuid
+
+    if link_class_changed? || tail_uuid_changed? || head_uuid_changed?
+      raise "Can only alter permission link level"
+    end
+  end
+
+  PERM_LEVEL = {
+    'can_read' => 1,
+    'can_login' => 1,
+    'can_write' => 2,
+    'can_manage' => 3,
+  }
+
+  def call_update_permissions
+    if self.link_class == 'permission'
+      update_permissions tail_uuid, head_uuid, PERM_LEVEL[name], self.uuid
+      current_user.forget_cached_group_perms
+    end
+  end
+
+  def clear_permissions
     if self.link_class == 'permission'
-      # Clearing the entire permissions cache can generate many
-      # unnecessary queries if many active users are not affected by
-      # this change. In such cases it would be better to search cached
-      # permissions for head_uuid and tail_uuid, and invalidate the
-      # cache for only those users. (This would require a browseable
-      # cache.)
-      User.invalidate_permissions_cache
+      update_permissions tail_uuid, head_uuid, REVOKE_PERM, self.uuid
+      current_user.forget_cached_group_perms
     end
   end
 
-  def name_link_has_valid_name
+  def check_permissions
+    if self.link_class == 'permission'
+      check_permissions_against_full_refresh
+    end
+  end
+
+  def name_links_are_obsolete
     if link_class == 'name'
-      unless name.is_a? String and !name.empty?
-        errors.add('name', 'must be a non-empty string')
-      end
+      errors.add('name', 'Name links are obsolete')
+      false
     else
       true
     end
   end
+
+  # A user is permitted to create, update or modify a permission link
+  # if and only if they have "manage" permission on the object
+  # indicated by the permission link's head_uuid.
+  #
+  # All other links are treated as regular ArvadosModel objects.
+  #
+  def ensure_owner_uuid_is_permitted
+    if link_class == 'permission'
+      ob = ArvadosModel.find_by_uuid(head_uuid)
+      raise PermissionDeniedError unless current_user.can?(manage: ob)
+      # All permission links should be owned by the system user.
+      self.owner_uuid = system_user_uuid
+      return true
+    else
+      super
+    end
+  end
 end