Is it permissible for teachers to take money generated from selling food and sweets to children in the canteen, knowing that they pay a portion of the profit to purchase school supplies and pay workers' wages?

Whoever acquires a permissible commodity and sells it in a valid sale is entitled to its price and profit. Permission must be obtained from the school owner or its administration before establishing a cafeteria for selling, because it is not permissible to exploit another's property except with their permission, as the Prophet, peace and blessings be upon him, said: "The property of a Muslim is not lawful except with his willing consent."