fix(actions): restore pushes to protected branches (#39564) (#39567)

Backport #39564 by @bircni

Use the Actions token's loaded write permission when checking
protected-branch pushes. Preserve push and force-push allowlists and add
regression coverage.

Fixes: https://github.com/go-gitea/gitea/issues/39563
Co-authored-by: bircni <bircni@icloud.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>

routers/private/hook_pre_receive.go

@@ -229,9 +229,9 @@ func preReceiveBranch(ctx *preReceiveContext, oldCommitID, newCommitID string, r
 		}
 	} else {
 		if isForcePush {
-			canPush = !changedProtectedfiles && protectBranch.CanUserForcePush(ctx, ctx.Doer)
+			canPush = !changedProtectedfiles && protectBranch.CanUserForcePush(ctx, ctx.Doer, ctx.Repo.Permission)
 		} else {
-			canPush = !changedProtectedfiles && protectBranch.CanUserPush(ctx, ctx.Doer)
+			canPush = !changedProtectedfiles && protectBranch.CanUserPush(ctx, ctx.Doer, ctx.Repo.Permission)
 		}
 	}
 

routers/private/hook_pre_receive_test.go

@@ -6,16 +6,67 @@ package private
 import (
 	"testing"
 
+	"gitea.dev/models/db"
+	git_model "gitea.dev/models/git"
 	issues_model "gitea.dev/models/issues"
 	repo_model "gitea.dev/models/repo"
 	"gitea.dev/models/unittest"
+	user_model "gitea.dev/models/user"
 	"gitea.dev/modules/git"
+	"gitea.dev/modules/private"
 	"gitea.dev/services/contexttest"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
+func TestPreReceiveActionsProtectedBranch(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+	for _, tc := range []struct {
+		name       string
+		protection git_model.ProtectedBranch
+		forcePush  bool
+		allowed    bool
+	}{
+		{name: "push", protection: git_model.ProtectedBranch{CanPush: true}, allowed: true},
+		{name: "push allowlist", protection: git_model.ProtectedBranch{CanPush: true, EnableWhitelist: true}},
+		{name: "force push", protection: git_model.ProtectedBranch{CanPush: true, CanForcePush: true}, forcePush: true, allowed: true},
+		{name: "force push allowlist", protection: git_model.ProtectedBranch{CanPush: true, CanForcePush: true, EnableForcePushAllowlist: true}, forcePush: true},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			mockCtx, resp := contexttest.MockPrivateContext(t, "/")
+			ctx := &preReceiveContext{PrivateContext: mockCtx, opts: &private.HookOptions{UserID: user_model.ActionsUserID}}
+			ctx.SetPathParam("owner", "user2")
+			ctx.SetPathParam("repo", "repo2")
+			RepoAssignment(ctx.PrivateContext)
+			require.False(t, ctx.Written())
+			defer ctx.Repo.GitRepo.Close()
+
+			doer := user_model.NewActionsUserWithTaskID(53)
+			loadContextDoerPermission(ctx.PrivateContext, doer.ID, doer.ExtDoerData.EncodeToString())
+
+			protection := tc.protection
+			protection.RepoID = ctx.Repo.Repository.ID
+			protection.RuleName = "probe"
+			require.NoError(t, db.Insert(t.Context(), &protection))
+			defer func() {
+				require.NoError(t, git_model.DeleteProtectedBranch(t.Context(), ctx.Repo.Repository, protection.ID))
+			}()
+
+			oldCommitID, newCommitID := "205ac761f3326a7ebe416e8673760016450b5cec", "1032bbf17fbc0d9c95bb5418dabe8f8c99278700"
+			if tc.forcePush {
+				oldCommitID, newCommitID = newCommitID, oldCommitID
+			}
+			preReceiveBranch(ctx, oldCommitID, newCommitID, git.RefNameFromBranch("probe"))
+			if tc.allowed {
+				assert.False(t, ctx.Written(), resp.Body.String())
+			} else {
+				assert.Contains(t, resp.Body.String(), "Not allowed to")
+			}
+		})
+	}
+}
+
 // TestPreReceiveCanWriteCodePerBranch ensures the maintainer-edit write grant is evaluated against
 // the exact ref being pushed on every call, derived from that ref rather than shared mutable state.
 // Otherwise, a per-branch grant (an open PR with "allow edits from maintainers") could be batched