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>

models/actions/run.go

@@ -32,11 +32,13 @@ type ActionRun struct {
 	OwnerID           int64                  `xorm:"index"`
 	WorkflowID        string                 `xorm:"index"`                    // the name of workflow file
 	Index             int64                  `xorm:"index unique(repo_index)"` // a unique number for each run of a repository
-	TriggerUserID     int64
-	TriggerUser       *user_model.User `xorm:"-"`
+	TriggerUserID     int64                  `xorm:"index"`
+	TriggerUser       *user_model.User       `xorm:"-"`
 	Ref               string
 	CommitSHA         string
 	IsForkPullRequest bool
+	NeedApproval      bool  // may need approval if it's a fork pull request
+	ApprovedBy        int64 `xorm:"index"` // who approved
 	Event             webhook_module.HookEventType
 	EventPayload      string `xorm:"LONGTEXT"`
 	Status            Status `xorm:"index"`
@@ -164,10 +166,6 @@ func InsertRun(ctx context.Context, run *ActionRun, jobs []*jobparser.SingleWork
 	}
 	run.Index = index
 
-	if run.Status.IsUnknown() {
-		run.Status = StatusWaiting
-	}
-
 	if err := db.Insert(ctx, run); err != nil {
 		return err
 	}
@@ -191,7 +189,7 @@ func InsertRun(ctx context.Context, run *ActionRun, jobs []*jobparser.SingleWork
 		job.EraseNeeds()
 		payload, _ := v.Marshal()
 		status := StatusWaiting
-		if len(needs) > 0 {
+		if len(needs) > 0 || run.NeedApproval {
 			status = StatusBlocked
 		}
 		runJobs = append(runJobs, &ActionRunJob{

models/actions/run_list.go

@@ -68,6 +68,8 @@ type FindRunOptions struct {
 	OwnerID          int64
 	IsClosed         util.OptionalBool
 	WorkflowFileName string
+	TriggerUserID    int64
+	Approved         bool // not util.OptionalBool, it works only when it's true
 }
 
 func (opts FindRunOptions) toConds() builder.Cond {
@@ -89,6 +91,12 @@ func (opts FindRunOptions) toConds() builder.Cond {
 	if opts.WorkflowFileName != "" {
 		cond = cond.And(builder.Eq{"workflow_id": opts.WorkflowFileName})
 	}
+	if opts.TriggerUserID > 0 {
+		cond = cond.And(builder.Eq{"trigger_user_id": opts.TriggerUserID})
+	}
+	if opts.Approved {
+		cond = cond.And(builder.Gt{"approved_by": 0})
+	}
 	return cond
 }
 

models/actions/status.go

@@ -82,6 +82,10 @@ func (s Status) IsRunning() bool {
 	return s == StatusRunning
 }
 
+func (s Status) IsBlocked() bool {
+	return s == StatusBlocked
+}
+
 // In returns whether s is one of the given statuses
 func (s Status) In(statuses ...Status) bool {
 	for _, v := range statuses {

models/migrations/migrations.go

@@ -19,6 +19,7 @@ import (
 	"code.gitea.io/gitea/models/migrations/v1_17"
 	"code.gitea.io/gitea/models/migrations/v1_18"
 	"code.gitea.io/gitea/models/migrations/v1_19"
+	"code.gitea.io/gitea/models/migrations/v1_20"
 	"code.gitea.io/gitea/models/migrations/v1_6"
 	"code.gitea.io/gitea/models/migrations/v1_7"
 	"code.gitea.io/gitea/models/migrations/v1_8"
@@ -463,6 +464,9 @@ var migrations = []Migration{
 	NewMigration("Add exclusive label", v1_19.AddExclusiveLabel),
 
 	// Gitea 1.19.0 ends at v244
+
+	// v244 -> v245
+	NewMigration("Add NeedApproval to actions tables", v1_20.AddNeedApprovalToActionRun),
 }
 
 // GetCurrentDBVersion returns the current db version

models/migrations/v1_20/v244.go

@@ -0,0 +1,22 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_20 //nolint
+
+import (
+	"xorm.io/xorm"
+)
+
+func AddNeedApprovalToActionRun(x *xorm.Engine) error {
+	/*
+		New index: TriggerUserID
+		New fields: NeedApproval, ApprovedBy
+	*/
+	type ActionRun struct {
+		TriggerUserID int64 `xorm:"index"`
+		NeedApproval  bool  // may need approval if it's a fork pull request
+		ApprovedBy    int64 `xorm:"index"` // who approved
+	}
+
+	return x.Sync(new(ActionRun))
+}