Require approval to run actions for fork pull request (#22803)

Currently, Gitea will run actions automatically which are triggered by
fork pull request. It's a security risk, people can create a PR and
modify the workflow yamls to execute a malicious script.

So we should require approval for first-time contributors, which is the
default strategy of a public repo on GitHub, see [Approving workflow
runs from public
forks](https://docs.github.com/en/actions/managing-workflow-runs/approving-workflow-runs-from-public-forks).

Current strategy:

- don't need approval if it's not a fork PR;
- always need approval if the user is restricted;
- don't need approval if the user can write;
- don't need approval if the user has been approved before;
- otherwise, need approval.

https://user-images.githubusercontent.com/9418365/217207121-badf50a8-826c-4425-bef1-d82d1979bc81.mov

GitHub has an option for that, you can see that at
`/<owner>/<repo>/settings/actions`, and we can support that later.

<img width="835" alt="image"
src="https://user-images.githubusercontent.com/9418365/217199990-2967e68b-e693-4e59-8186-ab33a1314a16.png">

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

1 files changed, 46 insertions, 2 deletions

diff --git a/services/actions/notifier_helper.go b/services/actions/notifier_helper.go
index df67d2fa1..ef63b8cf9 100644
--- a/services/actions/notifier_helper.go
+++ b/services/actions/notifier_helper.go
@@ -153,7 +153,7 @@ func notify(ctx context.Context, input *notifyInput) error {
 	}
 
 	for id, content := range workflows {
-		run := actions_model.ActionRun{
+		run := &actions_model.ActionRun{
 			Title:             strings.SplitN(commit.CommitMessage, "\n", 2)[0],
 			RepoID:            input.Repo.ID,
 			OwnerID:           input.Repo.OwnerID,
@@ -166,12 +166,19 @@ func notify(ctx context.Context, input *notifyInput) error {
 			EventPayload:      string(p),
 			Status:            actions_model.StatusWaiting,
 		}
+		if need, err := ifNeedApproval(ctx, run, input.Repo, input.Doer); err != nil {
+			log.Error("check if need approval for repo %d with user %d: %v", input.Repo.ID, input.Doer.ID, err)
+			continue
+		} else {
+			run.NeedApproval = need
+		}
+
 		jobs, err := jobparser.Parse(content)
 		if err != nil {
 			log.Error("jobparser.Parse: %v", err)
 			continue
 		}
-		if err := actions_model.InsertRun(ctx, &run, jobs); err != nil {
+		if err := actions_model.InsertRun(ctx, run, jobs); err != nil {
 			log.Error("InsertRun: %v", err)
 			continue
 		}
@@ -234,3 +241,40 @@ func notifyPackage(ctx context.Context, sender *user_model.User, pd *packages_mo
 		}).
 		Notify(ctx)
 }
+
+func ifNeedApproval(ctx context.Context, run *actions_model.ActionRun, repo *repo_model.Repository, user *user_model.User) (bool, error) {
+	// don't need approval if it's not a fork PR
+	if !run.IsForkPullRequest {
+		return false, nil
+	}
+
+	// always need approval if the user is restricted
+	if user.IsRestricted {
+		log.Trace("need approval because user %d is restricted", user.ID)
+		return true, nil
+	}
+
+	// don't need approval if the user can write
+	if perm, err := access_model.GetUserRepoPermission(ctx, repo, user); err != nil {
+		return false, fmt.Errorf("GetUserRepoPermission: %w", err)
+	} else if perm.CanWrite(unit_model.TypeActions) {
+		log.Trace("do not need approval because user %d can write", user.ID)
+		return false, nil
+	}
+
+	// don't need approval if the user has been approved before
+	if count, err := actions_model.CountRuns(ctx, actions_model.FindRunOptions{
+		RepoID:        repo.ID,
+		TriggerUserID: user.ID,
+		Approved:      true,
+	}); err != nil {
+		return false, fmt.Errorf("CountRuns: %w", err)
+	} else if count > 0 {
+		log.Trace("do not need approval because user %d has been approved before", user.ID)
+		return false, nil
+	}
+
+	// otherwise, need approval
+	log.Trace("need approval because it's the first time user %d triggered actions", user.ID)
+	return true, nil
+}