Earlier this week, Google began rolling out Android 6.0 Marshmallow to their current Nexus line up, which includes the Nexus 5, Nexus 6, Nexus 7 (2013), Nexus 9 and the Nexus Player. Now the OTA's are rolling out pretty steadily, and the factory images are already available. But for some, they have been waiting for a way to root once they get onto Marshmallow. Many need root for everyday tasks they do on their phone. For those unaware, Root is like getting admin rights on your computer, but for your smartphone. It basically means you can do anything. And there are many apps that need root to work, one common one is a file explorer by the name of "Root Explorer".
There is already a new beta of the SuperSU app, in version 2.50, which gives you root in Marshmallow. However you will need to flash a modified boot image. What this does, is it allows you to get root access on your device with SELinux set to enforcing mode. However, it is worth noting here that on devices that have forced encryption, like the Nexus 6 and Nexus 9, you may end up with factory resets. Luckily there's an easy way around that. Just install TWRP and you can sideload the beta of SuperSU very easily to your device. Chainfire, the maker of SuperSU, is indeed looking for a way to root Marshmallow without needing to use a modified kernel. But with security pretty tight on Android devices these days, it might be a bit tougher than previously. Thanks to additions like enterprise security and Android Pay. Which makes it understandable why security is tighter now.
One of the big reasons a lot of users get a Nexus is for the easy rooting. It's the easiest smartphone to root, and ROM. While many others are much more difficult, comparatively, especially Samsung and LG devices. Hopefully Chainfire can find an easier way to get Marshmallow devices rooted, but for now this is better than nothing. So far there aren't a whole lot of Marshmallow ROMs available, mostly because Google just started the code push to AOSP earlier this week and that does take some time.