How are transits done in Sao Paulo, I have both legs in Air Canada?
In Brazil you will go through passport control whenever you enter/exit the country. If your final destination is Canada and your bags will be sent there, you will still need to go through immigration at GRU. Air Canada flies out of Terminal 3, which does not handle domestic flights, so your domestic flight will arrive at another terminal. So yes, you will definitely go through passport control.