The Canadian government has indicated it is looking for legal opinions on bombing Syria. International Human Rights Lawyer David Jacobs says that they can look no further: the UN Charter clearly states that war is permissible only in self defence, or under the authority of the UN Security Council.
There is no Security Council resolution allowing Canada to bomb in Syria, and no need for self-defense. Bombing inside Syria is an act of war, just as would be the bombing of a Canadian province by a foreign power.