Merge branch 'project-existence-leak' into 'master'

Don't leak information about private project existence via Git-over-SSH/HTTP.

Fixes #2040 and https://gitlab.com/gitlab-org/gitlab-ce/issues/343.

Both `Grack::Auth` (used by Git-over-HTTP) and `Api::Internal /allowed` (used by gitlab-shell/Git-over-SSH) now return a generic "Not Found" error when the project exists but the user doesn't have access to it.

See merge request !1578

2 files changed, 50 insertions, 41 deletions

diff --git a/lib/api/internal.rb b/lib/api/internal.rb
index ba3fe619b92..753d0fcbd98 100644
--- a/lib/api/internal.rb
+++ b/lib/api/internal.rb
@@ -16,6 +16,17 @@ module API
       #
       post "/allowed" do
         status 200
+
+        actor = if params[:key_id]
+                  Key.find_by(id: params[:key_id])
+                elsif params[:user_id]
+                  User.find_by(id: params[:user_id])
+                end
+
+        unless actor
+          return Gitlab::GitAccessStatus.new(false, 'No such user or key')
+        end
+
         project_path = params[:project]
 
         # Check for *.wiki repositories.
@@ -32,26 +43,20 @@ module API
 
         project = Project.find_with_namespace(project_path)
 
-        unless project
-          return Gitlab::GitAccessStatus.new(false, 'No such project')
+        if project
+          status = access.check(
+            actor,
+            params[:action],
+            project,
+            params[:changes]
+          )
         end
 
-        actor = if params[:key_id]
-                  Key.find_by(id: params[:key_id])
-                elsif params[:user_id]
-                  User.find_by(id: params[:user_id])
-                end
-
-        unless actor
-          return Gitlab::GitAccessStatus.new(false, 'No such user or key')
+        if project && status && status.allowed?
+          status
+        else
+          Gitlab::GitAccessStatus.new(false, 'No such project')
         end
-
-        access.check(
-          actor,
-          params[:action],
-          project,
-          params[:changes]
-        )
       end
 
       #
diff --git a/lib/gitlab/backend/grack_auth.rb b/lib/gitlab/backend/grack_auth.rb
index dc4b945f9d4..ee877e099b1 100644
--- a/lib/gitlab/backend/grack_auth.rb
+++ b/lib/gitlab/backend/grack_auth.rb
@@ -10,8 +10,9 @@ module Grack
       @request = Rack::Request.new(env)
       @auth = Request.new(env)
 
-      # Need this patch due to the rails mount
+      @gitlab_ci = false
 
+      # Need this patch due to the rails mount
       # Need this if under RELATIVE_URL_ROOT
       unless Gitlab.config.gitlab.relative_url_root.empty?
         # If website is mounted using relative_url_root need to remove it first
@@ -22,8 +23,12 @@ module Grack
 
       @env['SCRIPT_NAME'] = ""
 
-      if project
-        auth!
+      auth!
+
+      if project && authorized_request?
+        @app.call(env)
+      elsif @user.nil? && !@gitlab_ci
+        unauthorized
       else
         render_not_found
       end
@@ -32,35 +37,30 @@ module Grack
     private
 
     def auth!
-      if @auth.provided?
-        return bad_request unless @auth.basic?
-
-        # Authentication with username and password
-        login, password = @auth.credentials
+      return unless @auth.provided?
 
-        # Allow authentication for GitLab CI service
-        # if valid token passed
-        if gitlab_ci_request?(login, password)
-          return @app.call(env)
-        end
+      return bad_request unless @auth.basic?
 
-        @user = authenticate_user(login, password)
+      # Authentication with username and password
+      login, password = @auth.credentials
 
-        if @user
-          Gitlab::ShellEnv.set_env(@user)
-          @env['REMOTE_USER'] = @auth.username
-        end
+      # Allow authentication for GitLab CI service
+      # if valid token passed
+      if gitlab_ci_request?(login, password)
+        @gitlab_ci = true
+        return
       end
 
-      if authorized_request?
-        @app.call(env)
-      else
-        unauthorized
+      @user = authenticate_user(login, password)
+
+      if @user
+        Gitlab::ShellEnv.set_env(@user)
+        @env['REMOTE_USER'] = @auth.username
       end
     end
 
     def gitlab_ci_request?(login, password)
-      if login == "gitlab-ci-token" && project.gitlab_ci?
+      if login == "gitlab-ci-token" && project && project.gitlab_ci?
         token = project.gitlab_ci_service.token
 
         if token.present? && token == password && git_cmd == 'git-upload-pack'
@@ -107,6 +107,8 @@ module Grack
     end
 
     def authorized_request?
+      return true if @gitlab_ci
+
       case git_cmd
       when *Gitlab::GitAccess::DOWNLOAD_COMMANDS
         if user
@@ -141,7 +143,9 @@ module Grack
     end
 
     def project
-      @project ||= project_by_path(@request.path_info)
+      return @project if defined?(@project)
+
+      @project = project_by_path(@request.path_info)
     end
 
     def project_by_path(path)