No matter if we use the old, buggy, error prone am_proc_start monitoring,
or the new APK inotify method, both methods rely on MagiskHide 'reacting'
fast enough to hijack the process before any detection has been done.
However, this is not reliable and practical. There are apps that utilize
native libraries to start detects and register SIGCONT signal handlers
to mitigate all existing MagiskHide process monitoring mechanism. So
our only solution is to hijack an app BEFORE it is started.
All Android apps' process is forked from zygote, so it is easily the
target to be monitored. All forks will be notified, and subsequent
thread spawning (Android apps are heaviliy multithreaded) from children
are also closely monitored to find the earliest possible point to
identify what the process will eventually be (before am_proc_bound).
ptrace is extremely complicated and very difficult to get right. The
current code is heaviliy tested on a stock Android 9.0 Pixel system,
so in theory it should work fine on most devices, but more tests and
potentially fixes are expected to follow this commit.
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.
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.
Since we are parsing through /data/app/ to find target APKs for
monitoring, system apps will not be covered in this case.
Automatically reinstall system apps as if they received an update
and refresh the monitor target after it's done.
As a bonus, use RAII idioms for locking pthread_mutex_t.
- Fail fast on unsupported systems
- Show proper fail message on unsupported systems
- inotify_fd shall be swapped out before closing to prevent
the proc_monitor thread to read from incomplete inotify fd
- Directly get UID instead of traversing /data/data everytime
- Use /data/user_de/0 instead of /data/data on Android 7.0+
- Update hide_uid set incrementally when adding/initializing targets
- Guard hide_uid set with the same lock as hide_list vector
- Do not add GMS package into database; only add to in-memory list
With the new detection method, it is impossible to check for components.
Remove additional checks for components and simply hardcode string to
proc_monitor.cpp and query cmdline to see if it's GMS unstable.
This addresses wasted resources on applying custom namespace
on all GMS processes.
Signed-off-by: Park Ju Hyung <qkrwngud825@gmail.com>
Previous MagiskHide detects new app launches via listening through logcat
and filtering launch info messages.
This is extremely inefficient and prone to cause multiple issues both
theoratically and practically.
Rework this by using inotify to detect open() syscalls to target APKs.
This also solves issues related to Zygote-forked caching mechanisms such as
OnePlus OxygenOS' embryo.
Signed-off-by: Park Ju Hyung <qkrwngud825@gmail.com>
