You just need a decent sized needle. Curved or half curved. Make sure you use cotton, not synthetic thread, a canvas tent relys on the stitching swelling slightly when it gets wet to form a watertight seal.
For tears in a canvas tent, I'd suggest using Ford Interlocking pattern. It's what I use to stitch up cows.
I have effected many repairs on my Vango force 10 using this pattern.