[{_id:1,objects:[{prop_1:"...",foo:true},{prop_1:"...",foo:false},{prop_1:"..."}]},{_id:2,objects:[{prop_1:"...",foo:false},{prop_1:"...",foo:false},{prop_1:"..."}]},{_id:3,objects:[{prop_1:"...",foo:true},{prop_1:"...",foo:true},{prop_1:"...",foo:true}]}]

db.collection.aggregate([{$match:{$expr:{$allElementsTrue:{$map:{input:"$objects",in:"$$this.foo"}}}}}])