Merge branch 'fix/git-access-wiki-when-repository-feature-disabled' into 'master'

Fixes access to the wiki code with git when repository feature disabled

## What does this MR do?

Allow access to the wiki repository with git when the repository feature is disabled.

## Why was this MR needed?

Without this fix, if you create a wiki only project you are not allowed to download the wiki code from this project.

## Does this MR meet the acceptance criteria?

- [X] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [ ] ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- [ ] ~~API support added~~
- Tests
  - [X] Added for this feature/bug
  - [ ] All builds are passing
- [X] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [X] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [X] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?

Fixes #24931

See merge request !7832

app/policies/project_policy.rb

@@ -50,6 +50,7 @@ class ProjectPolicy < BasePolicy
 
   def reporter_access!
     can! :download_code
+    can! :download_wiki_code
     can! :fork_project
     can! :create_project_snippet
     can! :update_issue
@@ -187,6 +188,7 @@ class ProjectPolicy < BasePolicy
 
     unless project.feature_available?(:wiki, user) || project.has_external_wiki?
       cannot!(*named_abilities(:wiki))
+      cannot!(:download_wiki_code)
     end
 
     unless project.feature_available?(:builds, user) && repository_enabled
@@ -226,6 +228,7 @@ class ProjectPolicy < BasePolicy
     can! :read_commit_status
     can! :read_container_image
     can! :download_code
+    can! :download_wiki_code
     can! :read_cycle_analytics
 
     # NOTE: may be overridden by IssuePolicy

changelogs/unreleased/fix-git-access-wiki-when-repository-feature-disabled.yml

+---
+title: Allow access to the wiki with git when repository feature disabled
+merge_request: 
+author: 

lib/gitlab/git_access.rb

@@ -46,7 +46,7 @@ module Gitlab
     def download_access_check
       if user
         user_download_access_check
-      elsif deploy_key.nil? && !Guest.can?(:download_code, project)
+      elsif deploy_key.nil? && !guest_can_downlod_code?
         raise UnauthorizedError, ERROR_MESSAGES[:download]
       end
     end
@@ -59,6 +59,10 @@ module Gitlab
       end
     end
 
+    def guest_can_downlod_code?
+      Guest.can?(:download_code, project)
+    end
+
     def user_download_access_check
       unless user_can_download_code? || build_can_download_code?
         raise UnauthorizedError, ERROR_MESSAGES[:download]

lib/gitlab/git_access_wiki.rb

 module Gitlab
   class GitAccessWiki < GitAccess
+    def guest_can_downlod_code?
+      Guest.can?(:download_wiki_code, project)
+    end
+
+    def user_can_download_code?
+      authentication_abilities.include?(:download_code) && user_access.can_do_action?(:download_wiki_code)
+    end
+
     def change_access_check(change)
       if user_access.can_do_action?(:create_wiki)
         build_status_object(true)

spec/lib/gitlab/git_access_wiki_spec.rb

@@ -26,4 +26,29 @@ describe Gitlab::GitAccessWiki, lib: true do
   def changes
     ['6f6d7e7ed 570e7b2ab refs/heads/master']
   end
+
+  describe '#download_access_check' do
+    subject { access.check('git-upload-pack', '_any') }
+
+    before do
+      project.team << [user, :developer]
+    end
+
+    context 'when wiki feature is enabled' do
+      it 'give access to download wiki code' do
+        project.project_feature.update_attribute(:wiki_access_level, ProjectFeature::ENABLED)
+
+        expect(subject.allowed?).to be_truthy
+      end
+    end
+
+    context 'when wiki feature is disabled' do
+      it 'does not give access to download wiki code' do
+        project.project_feature.update_attribute(:wiki_access_level, ProjectFeature::DISABLED)
+
+        expect(subject.allowed?).to be_falsey
+        expect(subject.message).to match(/You are not allowed to download code/)
+      end
+    end
+  end
 end

spec/policies/project_policy_spec.rb

@@ -23,7 +23,7 @@ describe ProjectPolicy, models: true do
       :download_code, :fork_project, :create_project_snippet, :update_issue,
       :admin_issue, :admin_label, :admin_list, :read_commit_status, :read_build,
       :read_container_image, :read_pipeline, :read_environment, :read_deployment,
-      :read_merge_request
+      :read_merge_request, :download_wiki_code
     ]
   end
 
@@ -56,7 +56,8 @@ describe ProjectPolicy, models: true do
   let(:public_permissions) do
     [
       :download_code, :fork_project, :read_commit_status, :read_pipeline,
-      :read_container_image, :build_download_code, :build_read_container_image
+      :read_container_image, :build_download_code, :build_read_container_image,
+      :download_wiki_code
     ]
   end
 
@@ -87,6 +88,15 @@ describe ProjectPolicy, models: true do
     expect(Ability.allowed?(user, :read_issue, project)).to be_falsy
   end
 
+  it 'does not include the wiki permissions when the feature is disabled' do
+    project.project_feature.update_attribute(:wiki_access_level, ProjectFeature::DISABLED)
+    wiki_permissions = [:read_wiki, :create_wiki, :update_wiki, :admin_wiki, :download_wiki_code]
+
+    permissions = described_class.abilities(owner, project).to_set
+
+    expect(permissions).not_to include(*wiki_permissions)
+  end
+
   context 'abilities for non-public projects' do
     let(:project) { create(:empty_project, namespace: owner.namespace) }