Mount group issue #75
Description
Android version:15
Magisk version name:27.2-4
Magisk version code:27002
There is a feature in both standard Magisk and Kitsune. When using Denylist or MagiskHide on the target apps, the Master ID of the mount group read by the target apps will increase discontinuously.
For example, in standard Magisk, the growth of the mount group ID of apps outside the Denylist is 1.2.3.4.5, while the growth of the mount group of apps in the Denylist is 1.2.3.5, and some numbers will be skipped in the middle. In Kitsune, apps outside of MagiskHide will have one "skip", such as 1.2.3.4.6, while apps within MagiskHide will have two "skips", such as 1.2.4.6.
Some detectors and software will use this feature to determine whether the device is rooted, such as Native Detector and BDO online. Native Detector will prompt "Detected Mount Inconsistency Mount per id: x"
Magisk Alpha has solved this problem, but because it is closed source, I can't know how it solves this problem. However, after consulting some information, I found a method that Alpha may use to solve the problem. In the early stage of Magisk init, the file descriptor of the original namespace is saved. At this time, the mount group ID is continuous. When the apps in Denylist is started, it will use setns to switch back to the early namespace, so that the mount group ID of the target apps can be continuous.
The above is just the information I found that may solve the problem. There is no guarantee that it will solve the problem. If you need to test Alpha to see how it achieves mount group continuity, please test version 29001. There are some bugs in the latest version, which causes the problem of discontinuous mount groups to appear again in Alpha.
Could you solve this problem? Thank you very much.
Native Detector: https://github.com/reveny/Android-Native-Root-Detector/releases/tag/v7.2.0
(You need to turn on "Enable Experimental Detections" in the settings to detect the continuity of the mount group)