Disallow renote of direct note (#11970)

* chore: renoteに関するチェックをまとめる

* fix: ダイレクト投稿をrenoteできる

* fix(frontend): 自分のダイレクト投稿をrenoteできる

* docs(changelog): ダイレクト投稿をリノートできてしまう

* fix lint

* chore(backend): visibilityに関するエラーをApi Errorとして返す

4 files changed, 39 insertions, 13 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6959c8577c..2780ebb86a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,7 @@
 - Enhance: ソフトワードミュートとハードワードミュートは統合されました
 - Enhance: モデレーションログ機能の強化
 - Enhance: ローカリゼーションの更新
+- Fix: ダイレクト投稿をリノートできてしまう
 
 ### Client
 - Enhance: 二要素認証のバックアップコード一覧をテキストファイルでダウンロード可能に
diff --git a/packages/backend/src/core/NoteCreateService.ts b/packages/backend/src/core/NoteCreateService.ts
index e8e9973b6e..34d103df77 100644
--- a/packages/backend/src/core/NoteCreateService.ts
+++ b/packages/backend/src/core/NoteCreateService.ts
@@ -252,19 +252,30 @@ export class NoteCreateService implements OnApplicationShutdown {
 			}
 		}
 
-		// Renote対象が「ホームまたは全体」以外の公開範囲ならreject
-		if (data.renote && data.renote.visibility !== 'public' && data.renote.visibility !== 'home' && data.renote.userId !== user.id) {
-			throw new Error('Renote target is not public or home');
-		}
-
-		// Renote対象がpublicではないならhomeにする
-		if (data.renote && data.renote.visibility !== 'public' && data.visibility === 'public') {
-			data.visibility = 'home';
-		}
+		if (data.renote) {
+			switch (data.renote.visibility) {
+				case 'public':
+					// public noteは無条件にrenote可能
+					break;
+				case 'home':
+					// home noteはhome以下にrenote可能
+					if (data.visibility === 'public') {
+						data.visibility = 'home';
+					}
+					break;
+				case 'followers':
+					// 他人のfollowers noteはreject
+					if (data.renote.userId !== user.id) {
+						throw new Error('Renote target is not public or home');
+					}
 
-		// Renote対象がfollowersならfollowersにする
-		if (data.renote && data.renote.visibility === 'followers') {
-			data.visibility = 'followers';
+					// Renote対象がfollowersならfollowersにする
+					data.visibility = 'followers';
+					break;
+				case 'specified':
+					// specified / direct noteはreject
+					throw new Error('Renote target is not public or home');
+			}
 		}
 
 		// 返信対象がpublicではないならhomeにする
diff --git a/packages/backend/src/server/api/endpoints/notes/create.ts b/packages/backend/src/server/api/endpoints/notes/create.ts
index 37a0525e25..3ae4ac044a 100644
--- a/packages/backend/src/server/api/endpoints/notes/create.ts
+++ b/packages/backend/src/server/api/endpoints/notes/create.ts
@@ -57,6 +57,12 @@ export const meta = {
 			id: 'fd4cc33e-2a37-48dd-99cc-9b806eb2031a',
 		},
 
+		cannotRenoteDueToVisibility: {
+			message: 'You can not Renote due to target visibility.',
+			code: 'CANNOT_RENOTE_DUE_TO_VISIBILITY',
+			id: 'be9529e9-fe72-4de0-ae43-0b363c4938af',
+		},
+
 		noSuchReplyTarget: {
 			message: 'No such reply target.',
 			code: 'NO_SUCH_REPLY_TARGET',
@@ -231,6 +237,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 						throw new ApiError(meta.errors.youHaveBeenBlocked);
 					}
 				}
+
+				if (renote.visibility === 'followers' && renote.userId !== me.id) {
+					// 他人のfollowers noteはreject
+					throw new ApiError(meta.errors.cannotRenoteDueToVisibility);
+				} else if (renote.visibility === 'specified') {
+					// specified / direct noteはreject
+					throw new ApiError(meta.errors.cannotRenoteDueToVisibility);
+				}
 			}
 
 			let reply: MiNote | null = null;
diff --git a/packages/frontend/src/components/MkNote.vue b/packages/frontend/src/components/MkNote.vue
index 4860f42cdc..62deefc67d 100644
--- a/packages/frontend/src/components/MkNote.vue
+++ b/packages/frontend/src/components/MkNote.vue
@@ -215,7 +215,7 @@ const muted = ref($i ? checkWordMute(appearNote, $i, $i.mutedWords) : false);
 const translation = ref<any>(null);
 const translating = ref(false);
 const showTicker = (defaultStore.state.instanceTicker === 'always') || (defaultStore.state.instanceTicker === 'remote' && appearNote.user.instance);
-const canRenote = computed(() => ['public', 'home'].includes(appearNote.visibility) || appearNote.userId === $i.id);
+const canRenote = computed(() => ['public', 'home'].includes(appearNote.visibility) || (appearNote.visibility === 'followers' && appearNote.userId === $i.id));
 let renoteCollapsed = $ref(defaultStore.state.collapseRenotes && isRenote && (($i && ($i.id === note.userId || $i.id === appearNote.userId)) || (appearNote.myReaction != null)));
 
 const keymap = {