Check if user can read issue before being assigned

app/models/concerns/issuable.rb

@@ -97,9 +97,9 @@ module Issuable
 
     def update_assignee_cache_counts
       # make sure we flush the cache for both the old *and* new assignees(if they exist)
-      previous_assignee = User.find_by_id(assignee_id_was)
-      previous_assignee.try(:update_cache_counts)
-      assignee.try(:update_cache_counts)
+      previous_assignee = User.find_by_id(assignee_id_was) if assignee_id_was
+      previous_assignee.update_cache_counts if previous_assignee
+      assignee.update_cache_counts if assignee
     end
 
     # We want to use optimistic lock for cases when only title or description are involved

app/services/issuable_base_service.rb

@@ -44,14 +44,10 @@ class IssuableBaseService < BaseService
     SystemNoteService.change_time_spent(issuable, issuable.project, current_user)
   end
 
-  def filter_params(issuable_ability_name = :issue)
-    filter_assignee
-    filter_milestone
-    filter_labels
+  def filter_params(issuable)
+    ability_name = :"admin_#{issuable.to_ability_name}"
 
-    ability = :"admin_#{issuable_ability_name}"
-
-    unless can?(current_user, ability, project)
+    unless can?(current_user, ability_name, project)
       params.delete(:milestone_id)
       params.delete(:labels)
       params.delete(:add_label_ids)
@@ -60,14 +56,35 @@ class IssuableBaseService < BaseService
       params.delete(:assignee_id)
       params.delete(:due_date)
     end
+
+    filter_assignee(issuable)
+    filter_milestone
+    filter_labels
   end
 
-  def filter_assignee
-    if params[:assignee_id] == IssuableFinder::NONE
-      params[:assignee_id] = ''
+  def filter_assignee(issuable)
+    return unless params[:assignee_id].present?
+
+    assignee_id = params[:assignee_id]
+
+    if assignee_id.to_s == IssuableFinder::NONE
+      params[:assignee_id] = ""
+    else
+      params.delete(:assignee_id) unless assignee_can_read?(issuable, assignee_id)
     end
   end
 
+  def assignee_can_read?(issuable, assignee_id)
+    new_assignee = User.find_by_id(assignee_id)
+
+    return false unless new_assignee.present?
+
+    ability_name = :"read_#{issuable.to_ability_name}"
+    resource     = issuable.persisted? ? issuable : project
+
+    can?(new_assignee, ability_name, resource)
+  end
+
   def filter_milestone
     milestone_id = params[:milestone_id]
     return unless milestone_id
@@ -146,7 +163,7 @@ class IssuableBaseService < BaseService
 
   def create(issuable)
     merge_slash_commands_into_params!(issuable)
-    filter_params
+    filter_params(issuable)
     change_time_spent(issuable)
 
     params.delete(:state_event)
@@ -190,7 +207,7 @@ class IssuableBaseService < BaseService
     change_subscription(issuable)
     change_todo(issuable)
     time_spent = change_time_spent(issuable)
-    filter_params
+    filter_params(issuable)
     old_labels = issuable.labels.to_a
     old_mentioned_users = issuable.mentioned_users.to_a
 

app/services/issues/base_service.rb

@@ -17,10 +17,6 @@ module Issues
 
     private
 
-    def filter_params
-      super(:issue)
-    end
-
     def execute_hooks(issue, action = 'open')
       issue_data  = hook_data(issue, action)
       hooks_scope = issue.confidential? ? :confidential_issue_hooks : :issue_hooks

app/services/merge_requests/base_service.rb

@@ -38,10 +38,6 @@ module MergeRequests
 
     private
 
-    def filter_params
-      super(:merge_request)
-    end
-
     def merge_requests_for(branch)
       origin_merge_requests = @project.origin_merge_requests
         .opened.where(source_branch: branch).to_a

changelogs/unreleased/issue_22664.yml

 ---
-title: Fix issuable assignee update bug when previous assignee is null
+title: Check if user can read project before being assigned to issue
 merge_request:
 author:

spec/models/concerns/issuable_spec.rb

@@ -44,21 +44,40 @@ describe Issue, "Issuable" do
     it { expect(described_class).to respond_to(:assigned) }
   end
 
-  describe "after_save" do
+  describe "before_save" do
     describe "#update_cache_counts" do
       context "when previous assignee exists" do
-        it "user updates cache counts" do
+        before do
+          assignee = create(:user)
+          issue.project.team << [assignee, :developer]
+          issue.update(assignee: assignee)
+        end
+
+        it "updates cache counts for new assignee" do
+          user = create(:user)
+
           expect(user).to receive(:update_cache_counts)
 
           issue.update(assignee: user)
         end
+
+        it "updates cache counts for previous assignee" do
+          old_assignee = issue.assignee
+          allow(User).to receive(:find_by_id).with(old_assignee.id).and_return(old_assignee)
+
+          expect(old_assignee).to receive(:update_cache_counts)
+
+          issue.update(assignee: nil)
+        end
       end
 
       context "when previous assignee does not exist" do
-        it "does not raise error" do
-          issue.update(assignee_id: "")
+        before{ issue.update(assignee: nil) }
 
-          expect { issue.update(assignee_id: user) }.not_to raise_error
+        it "updates cache count for the new assignee" do
+          expect_any_instance_of(User).to receive(:update_cache_counts)
+
+          issue.update(assignee: user)
         end
       end
     end

spec/services/issuable/bulk_update_service_spec.rb

@@ -52,7 +52,10 @@ describe Issuable::BulkUpdateService, services: true do
 
     context 'when the new assignee ID is a valid user' do
       it 'succeeds' do
-        result = bulk_update(issue, assignee_id: create(:user).id)
+        new_assignee = create(:user)
+        project.team << [new_assignee, :developer]
+
+        result = bulk_update(issue, assignee_id: new_assignee.id)
 
         expect(result[:success]).to be_truthy
         expect(result[:count]).to eq(1)
@@ -60,15 +63,16 @@ describe Issuable::BulkUpdateService, services: true do
 
       it 'updates the assignee to the use ID passed' do
         assignee = create(:user)
+        project.team << [assignee, :developer]
 
         expect { bulk_update(issue, assignee_id: assignee.id) }
           .to change { issue.reload.assignee }.from(user).to(assignee)
       end
     end
 
-    context 'when the new assignee ID is -1' do
-      it 'unassigns the issues' do
-        expect { bulk_update(issue, assignee_id: -1) }
+    context "when the new assignee ID is #{IssuableFinder::NONE}" do
+      it "unassigns the issues" do
+        expect { bulk_update(issue, assignee_id: IssuableFinder::NONE) }
           .to change { issue.reload.assignee }.to(nil)
       end
     end

spec/services/issues/create_service_spec.rb

@@ -135,6 +135,8 @@ describe Issues::CreateService, services: true do
       end
     end
 
+    it_behaves_like 'issuable create service'
+
     it_behaves_like 'new issuable record that supports slash commands'
 
     context 'for a merge request' do

spec/services/issues/update_service_spec.rb

@@ -142,6 +142,17 @@ describe Issues::UpdateService, services: true do
 
         update_issue(confidential: true)
       end
+
+      it 'does not update assignee_id with unauthorized users' do
+        project.update(visibility_level: Gitlab::VisibilityLevel::PUBLIC)
+        update_issue(confidential: true)
+        non_member        = create(:user)
+        original_assignee = issue.assignee
+
+        update_issue(assignee_id: non_member.id)
+
+        expect(issue.reload.assignee_id).to eq(original_assignee.id)
+      end
     end
 
     context 'todos' do

spec/services/merge_requests/create_service_spec.rb

@@ -84,6 +84,8 @@ describe MergeRequests::CreateService, services: true do
       end
     end
 
+    it_behaves_like 'issuable create service'
+
     context 'while saving references to issues that the created merge request closes' do
       let(:first_issue) { create(:issue, project: project) }
       let(:second_issue) { create(:issue, project: project) }

spec/services/notes/slash_commands_service_spec.rb

@@ -5,6 +5,8 @@ describe Notes::SlashCommandsService, services: true do
     let(:project) { create(:empty_project) }
     let(:master) { create(:user).tap { |u| project.team << [u, :master] } }
     let(:assignee) { create(:user) }
+
+    before { project.team << [assignee, :master] }
   end
 
   shared_examples 'note on noteable that does not support slash commands' do

spec/support/services/issuable_create_service_shared_examples.rb

+shared_examples 'issuable create service' do
+  context 'asssignee_id' do
+    let(:assignee) { create(:user) }
+
+    before { project.team << [user, :master] }
+
+    it 'removes assignee_id when user id is invalid' do
+      opts = { title: 'Title', description: 'Description', assignee_id: -1 }
+
+      issuable = described_class.new(project, user, opts).execute
+
+      expect(issuable.assignee_id).to be_nil
+    end
+
+    it 'removes assignee_id when user id is 0' do
+      opts = { title: 'Title', description: 'Description',  assignee_id: 0 }
+
+      issuable = described_class.new(project, user, opts).execute
+
+      expect(issuable.assignee_id).to be_nil
+    end
+
+    it 'saves assignee when user id is valid' do
+      project.team << [assignee, :master]
+      opts = { title: 'Title', description: 'Description', assignee_id: assignee.id }
+
+      issuable = described_class.new(project, user, opts).execute
+
+      expect(issuable.assignee_id).to eq(assignee.id)
+    end
+
+    context "when issuable feature is private" do
+      before do
+        project.project_feature.update(issues_access_level: ProjectFeature::PRIVATE)
+        project.project_feature.update(merge_requests_access_level: ProjectFeature::PRIVATE)
+      end
+
+      levels = [Gitlab::VisibilityLevel::INTERNAL, Gitlab::VisibilityLevel::PUBLIC]
+
+      levels.each do |level|
+        it "removes not authorized assignee when project is #{Gitlab::VisibilityLevel.level_name(level)}" do
+          project.update(visibility_level: level)
+          opts = { title: 'Title', description: 'Description', assignee_id: assignee.id }
+
+          issuable = described_class.new(project, user, opts).execute
+
+          expect(issuable.assignee_id).to be_nil
+        end
+      end
+    end
+  end
+end

spec/support/services/issuable_create_service_slash_commands_shared_examples.rb

@@ -11,6 +11,8 @@ shared_examples 'new issuable record that supports slash commands' do
   let(:params) { base_params.merge(defined?(default_params) ? default_params : {}).merge(example_params) }
   let(:issuable) { described_class.new(project, user, params).execute }
 
+  before { project.team << [assignee, :master ] }
+
   context 'with labels in command only' do
     let(:example_params) do
       {
@@ -55,7 +57,7 @@ shared_examples 'new issuable record that supports slash commands' do
   context 'with assignee and milestone in params and command' do
     let(:example_params) do
       {
-        assignee: build_stubbed(:user),
+        assignee: create(:user),
         milestone_id: double(:milestone),
         description: %(/assign @#{assignee.username}\n/milestone %"#{milestone.name}")
       }

spec/support/services/issuable_update_service_shared_examples.rb

 shared_examples 'issuable update service' do
+  def update_issuable(opts)
+    described_class.new(project, user, opts).execute(open_issuable)
+  end
+
   context 'changing state' do
     before { expect(project).to receive(:execute_hooks).once }
 
@@ -14,4 +18,52 @@ shared_examples 'issuable update service' do
       end
     end
   end
+
+  context 'asssignee_id' do
+    it 'does not update assignee when assignee_id is invalid' do
+      open_issuable.update(assignee_id: user.id)
+
+      update_issuable(assignee_id: -1)
+
+      expect(open_issuable.reload.assignee).to eq(user)
+    end
+
+    it 'unassigns assignee when user id is 0' do
+      open_issuable.update(assignee_id: user.id)
+
+      update_issuable(assignee_id: 0)
+
+      expect(open_issuable.assignee_id).to be_nil
+    end
+
+    it 'saves assignee when user id is valid' do
+      update_issuable(assignee_id: user.id)
+
+      expect(open_issuable.assignee_id).to eq(user.id)
+    end
+
+    it 'does not update assignee_id when user cannot read issue' do
+      non_member        = create(:user)
+      original_assignee = open_issuable.assignee
+
+      update_issuable(assignee_id: non_member.id)
+
+      expect(open_issuable.assignee_id).to eq(original_assignee.id)
+    end
+
+    context "when issuable feature is private" do
+      levels = [Gitlab::VisibilityLevel::INTERNAL, Gitlab::VisibilityLevel::PUBLIC]
+
+      levels.each do |level|
+        it "does not update with unauthorized assignee when project is #{Gitlab::VisibilityLevel.level_name(level)}" do
+          assignee = create(:user)
+          project.update(visibility_level: level)
+          feature_visibility_attr = :"#{open_issuable.model_name.plural}_access_level"
+          project.project_feature.update_attribute(feature_visibility_attr, ProjectFeature::PRIVATE)
+
+          expect{ update_issuable(assignee_id: assignee) }.not_to change{ open_issuable.assignee }
+        end
+      end
+    end
+  end
 end