Guard entity access behind ScriptCanAccess

Co-authored-by: sappho <sappho@sappho.io>

Author: azzyr

src/game/client/c_basecombatweapon.cpp

@@ -688,3 +688,14 @@ void C_BaseCombatWeapon::GetToolRecordingState( KeyValues *msg )
 		SetModelIndex( nModelIndex );
 	}
 }
+
+#ifdef MAPBASE_MP
+bool C_BaseCombatWeapon::ScriptCanAccess()
+{
+	C_BasePlayer *pPlayer = C_BasePlayer::GetLocalPlayer();
+	if ( !pPlayer )
+		return false;
+
+    return GetOwner() == pPlayer;
+}
+#endif

src/game/client/c_baseentity.cpp

@@ -6689,21 +6689,12 @@ int C_BaseEntity::GetCreationTick() const
 HSCRIPT C_BaseEntity::GetScriptInstance()
 {
 #ifdef MAPBASE_MP
-	// No clientside entity access outside of worldspawn + local player and its children
-	if ( this != C_BasePlayer::GetLocalPlayer() && !IsWorld() )
+	// client script should only touch a small whitelist of local player related ents.
+	// we can not naively grant access based on move-parent hierarchy, server-parented props used
+	// in the BadMDL exploit chain bypassed the old check that way. sorry.
+	if ( !ScriptCanAccess() )
 	{
-		// See if the player is somewhere up our hierarchy
-		C_BaseEntity *pParent = GetMoveParent();
-		while ( pParent )
-		{
-			if ( pParent != C_BasePlayer::GetLocalPlayer() )
-				pParent = pParent->GetMoveParent();
-			else
-				break;
-		}
-
-		if ( !pParent )
-			return NULL;
+        return NULL;
 	}
 #endif
 

src/game/client/c_baseentity.h

@@ -296,6 +296,10 @@ class C_BaseEntity : public IClientEntity
 
 	HSCRIPT GetScriptInstance();
 
+#ifdef MAPBASE_MP
+    virtual bool ScriptCanAccess() { return false; }
+#endif
+
 	HSCRIPT			m_hScriptInstance;
 	string_t		m_iszScriptId;
 #ifdef MAPBASE_VSCRIPT

src/game/client/c_baseplayer.cpp

@@ -3255,6 +3255,13 @@ C_ColorCorrection* C_BasePlayer::GetActiveColorCorrection() const
 }
 #endif
 
+#ifdef MAPBASE_MP
+bool C_BasePlayer::ScriptCanAccess()
+{
+	return IsLocalPlayer();
+}
+#endif
+
 //-----------------------------------------------------------------------------
 // Purpose: 
 //-----------------------------------------------------------------------------

src/game/client/c_baseplayer.h

@@ -412,6 +412,10 @@ class C_BasePlayer : public C_BaseCombatCharacter, public CGameEventListener
 	C_ColorCorrection*		GetActiveColorCorrection() const;
 #endif
 
+#ifdef MAPBASE_MP
+    virtual bool			ScriptCanAccess() override;
+#endif
+
 	float					GetFOVTime( void ){ return m_flFOVTime; }
 
 	virtual void			OnAchievementAchieved( int iAchievement ) {}

src/game/client/c_baseviewmodel.cpp

@@ -510,3 +510,14 @@ RenderGroup_t C_BaseViewModel::GetRenderGroup()
 {
 	return RENDER_GROUP_VIEW_MODEL_OPAQUE;
 }
+
+#ifdef MAPBASE_MP
+bool C_BaseViewModel::ScriptCanAccess()
+{
+	C_BasePlayer *pPlayer = C_BasePlayer::GetLocalPlayer();
+	if ( !pPlayer )
+		return false;
+
+    return GetOwner() == pPlayer;
+}
+#endif

src/game/client/c_world.h

@@ -55,6 +55,10 @@ class C_World : public C_BaseEntity
 	ScriptLanguage_t GetScriptLanguage() { return (ScriptLanguage_t)(m_iScriptLanguageClient != -2 ? m_iScriptLanguageClient : m_iScriptLanguageServer); }
 #endif
 
+#ifdef MAPBASE_MP
+    virtual bool ScriptCanAccess() override { return true; }
+#endif
+
 public:
 	enum
 	{

src/game/shared/basecombatweapon_shared.h

@@ -652,6 +652,10 @@ class CBaseCombatWeapon : public BASECOMBATWEAPON_DERIVED_FROM
 	//Tony; notifications of any third person switches.
 	virtual void			ThirdPersonSwitch( bool bThirdPerson ) {};
 
+#if defined(CLIENT_DLL) && defined(MAPBASE_MP)
+    virtual bool			ScriptCanAccess() override;
+#endif
+
 #endif // End client-only methods
 
 	virtual bool			CanLower( void ) { return false; }

src/game/shared/baseviewmodel_shared.h

@@ -178,6 +178,10 @@ class CBaseViewModel : public CBaseAnimating, public IHasOwner
 	virtual bool			GetAttachmentVelocity( int number, Vector &originVel, Quaternion &angleVel );
 #endif
 
+#ifdef MAPBASE_MP
+    virtual bool			ScriptCanAccess() override;
+#endif
+
 private:
 	CBaseViewModel( const CBaseViewModel & ); // not defined, not accessible
 

src/game/shared/econ/econ_wearable.cpp

@@ -405,6 +405,18 @@ bool CEconWearable::ShouldDraw( void )
 	return BaseClass::ShouldDraw();
 }
 
+#if defined(CLIENT_DLL) && defined(MAPBASE_MP)
+bool CEconWearable::ScriptCanAccess()
+{
+	C_BasePlayer *pPlayer = C_BasePlayer::GetLocalPlayer();
+	if ( !pPlayer )
+		return false;
+
+    // wearables use m_hOwnerEntity instead of m_hOwner
+    return GetOwnerEntity() == pPlayer;
+}
+#endif
+
 //-----------------------------------------------------------------------------
 // Purpose:
 //-----------------------------------------------------------------------------