It's alright, but don't fool yourself into thinking that what you're doing is the same as barbell back squatting or deadlifting. It can't hurt, but it's like a half squat with the bar in your hands. If you got some straps, I would not be surprised if it went significantly beyond your squat and deadlift.
“I have a very simple rule when it comes to management: hire the best people from your competitors, pay them more than they were earning, and give them bonuses and incentives based on their performance. That’s how you build a first-class operation.”
― Donald J. Trump
If you want some PDF's on bodyweight exercise with little to no equipment, send me a PM and I'll get back to you as soon as possible.