If your rifle still has the factory gas block, stock, and handguard, you have a few ways you can go:
For the rear sling mounting point:
0) Replace the lame stock with a Magpul CTR. It has a QD sling swivel hole built onto the side of the stock. It costs about $90.
OR
1) Get a Magpul ASAP - it's a replacement for the stock end plate.
The stock would be easier to install because installing the ASAP requires that you remove the buffer tube, and deal with staking the castle nut when you put it all back together again.
On the front:
0) Replace the gas block with a Yankee-Hill quad-rail gas block, and buy a rail-mounted sling swivel.
OR
1) Replace the gas block with a Yankee-hill gas block/flip-up sight (one version of this comes with a sling swivel already built on). This is probably the best idea, because you get a sight with the gas block.
OR
2) Replace the handguard with something that allows you to attach a sling swivel adapter.