Diddy should watch his back in prison … ’cause a former warden at the facility he’s in says there are a whole lot of inmates who would see killing him as a badge of honor.

As you know, Diddy’s currently being held in MDC Brooklyn — a notorious federal detention facility in NYC — without bail. Sources with direct knowledge tell us Diddy’s being held in the Special Housing Unit, away from the general population.

Cameron Lindsay — former warden of MDC Brooklyn — tells TMZ Diddy’s location in the SHU makes sense because he’s a target behind bars … with his celebrity status and the nature of the allegations against him potentially bringing him unwanted attention from other inmates.

In the SHU, Lindsay says Diddy’s lifestyle will be heavily regimented … with just one hour of rec time per day and three showers a week. We’re told family and friends will be allowed to visit periodically … while his lawyers will have more access to work on his case.

A day in the life of Diddy … Cameron says he will receive a 6 AM wake-up call, at which time he will need to make his bed, mop the floor, and generally keep his cell clean.

We’re told he’ll receive three 1,800-calorie meals per day … all of which will be prepared early and will wait in a warming box for them to be given to him since he’s not in general population — meaning the lackluster prison food won’t be particularly fresh when he receives it.

Diddy has access to a commissary where he can buy smaller goods — like candy, coffee, tea, cheese — and also larger items like sweatpants, sneakers, and a radio.

James Kousouros, attorney to the rapper Casanova — who spent time at MDC Brooklyn before he was sentenced to 188 months last year for racketeering — tells TMZ conditions in the prison are even more dire than they sound.

Kousouros says regular fights and assaults break out in the prison itself … and, in the SHU, he says, Diddy will have a very limited amount of access to the library and the phone.

JK says it’s harder for visitors to come and see people in the SHU because it takes a long time to get up to the SHU … and, the prison doesn’t allocate more time — so, even with regular visitation, Diddy will still likely not see much of his family.