We used to construct /sbin tmpfs overlay in early-init stage after
SELinux is properly initialized. However the way it is implemented
(forking daemon from magiskinit with complicated file waiting triggers)
is extremely complicated and error prone.
This commit moves the construction of the sbin overlay to pre-init
stage. The catch is that since SELinux is not present at that point,
proper selabel has to be reconstructed afterwards. Some additional
SEPolicy rules are added to make sure init can access magisk binaries,
and the secontext relabeling task is assigned to the main Magisk daemon.
Shut down any UID matching process and resume if it turns out not to
be our target. Since we will record every single process we have ever
paused, this means that the same process will not be paused erroneously
for another time.
This is an optimization to hijack the app as soon as possible.
Before switching to the new MagiskHide implementation (APK inotify),
logcat parsing provides us lots of information to target a process.
We were targeting components so that apps with multi-processes
can still be hidden properly.
After switching to the new implementation, our granularity is limited
to the UID of the process. This is especially dangerous since Android
allow apps signed with the same signature to share UIDs, and many system
apps utilize this for elevated permissions for some services.
This commit introduces process name matching. We could not blanketly
target an UID, so the workaround is to verify its process name before
unmounting.
The tricky thing is that any app developer is allowed to name the
process of its component to whatever they want; there is no 'one
rule to catch them all' to target a specific package. As a result,
Magisk Manager is updated to scan through all components of all apps,
and show different processes of the same app, each as a separate
hide target in the list.
The hide target database also has to be updated accordingly.
Each hide target is now a <package name, process name> pair. The
magiskhide CLI and Magisk Manager is updated to support this new
target format.
Most Chinese devices (and supposedly Galaxy S10) running Android Pie
is using system-as-root without A/B partition.
https://source.android.com/devices/bootloader/system-as-root#about-system-as-root
According to the docs above, these devices will have a ramdisk block
with size 0 in their boot images. Since magiskinit can run independently
on system-as-root devices, we simply just create an empty ramdisk with
magiskinit added as init.
Huge thanks to @vvb2060 for the heads up and original PR.
Close#980, close#1102
Reinstalling system apps as data creates tons of issues.
Calling pm path <pkg> is extremely expensive and doesn't work in post-fs-data.
Parse through packages.xml to get APK path and UID at the same time.
As a bonus, we don't need to traverse /data/app for packages anymore.
