brazilian here:
The main problem, as far as I see, it's not the federal government: are the states and municipal ones.
The main riots begun against the price of the bus in the main cities (first in Porto Alegre in April, and took a big shape after Sao Paulo tried to raise the price of the bus ticket in may-june). People are beat by the local polices without clear reason (plus rubber bullets and moral gas) and lots of arrests are being made without a reason (in Sao Paulo the local police arrested hundreds of people with possession of VINEGAR*).
But look how crazy this sounds: the mayor of Sao Paulo (the city) is a left-wing (or center-left) workers party. The governor of Sao Paulo (the state) is a right-wing almost tea-party-look-a-like. The riots were against the mayor, but the state used its force (police). In porto alegre, the mayor is a center-right-wing and the state government is a left-wing workers party. The same: the riots were against the mayor, and the police (controled by the governor) was used in a brutal way (not so hard as sao paulo, but brutal) against the rioters.
Now that the main cities agreed to lower the price of the bus ticket (porto alegre in May and several other cities in the last few days), the riots looks more like french 68 riots than anything else. It's not about the price of the bus ticket anymore, but about the political and social culture in Brazil (corruption, a lack of social control, etc).
*Vinegar is used to decrease the effects of tear gas.
** One last thing: be careful with brazilian newspapers. Most of them will stand for its own agenda and they are part of the problem, not the solution.