Commit Graph

8 Commits

Author SHA1 Message Date
topjohnwu
f9bde347bc Convert indentation to spaces
The tab war is lost
2020-12-30 22:11:24 -08:00
topjohnwu
f152e8c33d Directly log to log file 2020-12-03 20:15:18 -08:00
topjohnwu
43146b8316 Update su request process
Due to changes in ec3705f2ed, the app can
no longer communicate with the dameon through a socket opened on the
daemon side due to SELinux restrictions. The workaround here is to have
the daemon decide a socket name, send it to the app, have the app create
the socket server, then finally the daemon connects to the app through
the socket.
2020-06-19 03:52:25 -07:00
topjohnwu
c7ed0ef5eb Fix SAR support for overlay.d 2020-04-25 23:19:36 -07:00
topjohnwu
9820296e92 Update files.cpp in libutils 2020-04-02 02:17:45 -07:00
topjohnwu
dbfde74c1e Clean rootfs in switch_root 2020-04-01 23:37:11 -07:00
topjohnwu
5f1174de27 Introduce new boot flow to handle SAR 2SI
The existing method for handling legacy SAR is:
1. Mount /sbin tmpfs overlay
2. Dump all patched/new files into /sbin
3. Magic mount root dir and re-exec patched stock init

With Android 11 removing the /sbin folder, it is quite obvious that
things completely break down right in step 1.

To overcome this issue, we have to find a way to swap out the init
binary AFTER we re-exec stock init. This is where 2SI comes to rescue!

2SI normal boot procedure is:
1st stage -> Load sepolicy -> 2nd stage -> boot continue...

2SI Magisk boot procedure is:
MagiskInit 1st stage -> Stock 1st stage -> MagiskInit 2nd Stage ->
-> Stock init load sepolicy -> Stock 2nd stage -> boot continue...

As you can see, the trick is to make stock 1st stage init re-exec back
into MagiskInit so we can do our setup. This is possible by manipulating
some ramdisk files on initramfs based 2SI devices (old ass non SAR
devices AND super modern devices like Pixel 3/4), but not possible
on device that are stuck using legacy SAR (device that are not that
modern but not too old, like Pixel 1/2. Fucking Google logic!!)

This commit introduces a new way to intercept stock init re-exec flow:
ptrace init with forked tracer, monitor PTRACE_EVENT_EXEC, then swap
out the init file with bind mounts right before execv returns!

Going through this flow however will lose some necessary backup files,
so some bookkeeping has to be done by making the tracer hold these
files in memory and act as a daemon. 2nd stage MagiskInit will ack the
daemon to release these files at the correct time.

It just works™  ¯\_(ツ)_/¯
2020-04-01 04:39:28 -07:00
topjohnwu
a0998009c1 Small native code reorganization 2020-03-09 01:50:30 -07:00