What is Fenrir

Fenrir tricks your phone into lying about its lock status.

Normally: unlock bootloader > banking apps and different apps stop working because Google sees you unlocked it and doesn't give you strong integrity. You need to find keyboxes and pif to pass strong integrity.

Fenrir: you have unlocked bootloader (root, custom ROM, whatever) but the phone tells every app "nah I'm still locked, promise" so apps which need integrity all stay happy thinking it's a stock untouched phone.

You don't need to find keybox or worry about that anymore.

Dirty flashing from old versions or OTA will not work, you need to wipe data for phone to boot.

ROOTING IF YOU HAVE FENRIR POSSIBLE?

Yes! You can patch init_boot with KernelSU, flash it & phone will boot and you will have root

That's the only thing i have tried so far. I have not tried GKI kernels or anything so patching init_boot is the only thing i can recommend.

Ask in community if someone tried those, just be careful, you might brick your phone.

YOU HAVE BEEN WARNED

IMPORTANT NOTE : MANY APPS STILL DETECT CUSTOM ROMS.

Fenrir is not a solution to bypass custom rom detections. It just removes the need for keybox and spoofs device as locked.

Fenrir patches lk.img of the rom and bypasses and spoofs checks at bootloader level.

Don't use the fenrir patched lk.img in aosp roms which don't have Fenrir support, it needs a few ROM source patches for it to work.

If you go from no fenrir to fenrir you will need to wipe your data otherwise phone will not boot and vice versa.

Cheers

Luxured