Check the grammar explanation here.

Here you are links with exercises to practice the passive tense:

1. Examenglish 
2. Agendaweb 
3. Esl-lounge 
4. Oxford University Press 
5. Englisch-hilfen 
6. Speak speak 
7. Learnenglishfeelgood 
8. English grammar (choose intermediate / advanced)

Exercises to practise the causative:

1. Perfect English Grammar
2. El aula de Isa (You’ve got the grammar explanation and the exercises at the bottom of the page)
3. Oxford University Press 
4. EUENGLISH 
5. Englishvocabularyexercises 
6. Ego4u 
7. Usingenglish