X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/c8b119d10b41cd507a6677d4feab7974362a153e..4a1735427d84743f6c2f3576263fdcae397cf9e9:/services/api/app/models/link.rb

diff --git a/services/api/app/models/link.rb b/services/api/app/models/link.rb
index 21d89767c7..4d4c2832bb 100644
--- a/services/api/app/models/link.rb
+++ b/services/api/app/models/link.rb
@@ -12,11 +12,15 @@ class Link < ArvadosModel
   attribute :properties, :jsonbHash, default: {}
 
   validate :name_links_are_obsolete
-  before_create :permission_to_attach_to_objects
-  before_update :permission_to_attach_to_objects
+  validate :permission_to_attach_to_objects
+  before_update :restrict_alter_permissions
+  before_update :apply_max_overlapping_permissions
+  before_create :apply_max_overlapping_permissions
+  after_update :delete_overlapping_permissions
   after_update :call_update_permissions
   after_create :call_update_permissions
   before_destroy :clear_permissions
+  after_destroy :delete_overlapping_permissions
   after_destroy :check_permissions
 
   api_accessible :user, extend: :common do |t|
@@ -29,6 +33,58 @@ class Link < ArvadosModel
     t.add :properties
   end
 
+  PermLevel = {
+    'can_read' => 0,
+    'can_write' => 1,
+    'can_manage' => 2,
+  }
+
+  def apply_max_overlapping_permissions
+    return if self.link_class != 'permission' || !PermLevel[self.name]
+    Link.
+      lock. # select ... for update
+      where(link_class: 'permission',
+            tail_uuid: self.tail_uuid,
+            head_uuid: self.head_uuid,
+            name: PermLevel.keys).
+      where('uuid <> ?', self.uuid).each do |other|
+      if PermLevel[other.name] > PermLevel[self.name]
+        self.name = other.name
+      end
+    end
+  end
+
+  def delete_overlapping_permissions
+    return if self.link_class != 'permission'
+    redundant = nil
+    if PermLevel[self.name]
+      redundant = Link.
+                    lock. # select ... for update
+                    where(link_class: 'permission',
+                          tail_uuid: self.tail_uuid,
+                          head_uuid: self.head_uuid,
+                          name: PermLevel.keys).
+                    where('uuid <> ?', self.uuid)
+    elsif self.name == 'can_login' &&
+          self.properties.respond_to?(:has_key?) &&
+          self.properties.has_key?('username')
+      redundant = Link.
+                    lock. # select ... for update
+                    where(link_class: 'permission',
+                          tail_uuid: self.tail_uuid,
+                          head_uuid: self.head_uuid,
+                          name: 'can_login').
+                    where('properties @> ?', SafeJSON.dump({'username' => self.properties['username']})).
+                    where('uuid <> ?', self.uuid)
+    end
+    if redundant
+      redundant.each do |link|
+        link.clear_permissions
+      end
+      redundant.delete_all
+    end
+  end
+
   def head_kind
     if k = ArvadosModel::resource_class_for_uuid(head_uuid)
       k.kind
@@ -43,6 +99,28 @@ 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
@@ -50,13 +128,42 @@ 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
 
     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
-    return false if head_obj.is_a?(Collection) && head_obj.current_version_uuid != head_uuid
+    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
 
     # All users can grant permissions on objects they own or can manage
     return true if current_user.can?(manage: head_obj)
@@ -65,6 +172,16 @@ class Link < ArvadosModel
     false
   end
 
+  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,
@@ -75,12 +192,14 @@ class Link < ArvadosModel
   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'
       update_permissions tail_uuid, head_uuid, REVOKE_PERM, self.uuid
+      current_user.forget_cached_group_perms
     end
   end