Commit Graph

15 Commits

Author SHA1 Message Date
topjohnwu
e0a281583d Preparation for dynamic tmpfs path 2020-04-12 05:34:56 -07:00
Shaka Huang
834561a5de Content in dt_fstab is not null terminated in emulator
Value of <dt>/fstab/<partition>/dev and <dt>/fstab/<partition>/type in official Android emulator ends with newline instead of \0, Magisk won’t be able to patch sepolicy and crash the system.

Signed-off-by: Shaka Huang <shakalaca@gmail.com>
2020-04-02 20:54:41 -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
543ce937ec Don't need to find system_dev 2020-03-31 22:41:25 -07:00
topjohnwu
a0998009c1 Small native code reorganization 2020-03-09 01:50:30 -07:00
topjohnwu
3b8ea599f0 Fix switch_root implementation 2020-02-20 21:08:59 -08:00
osm0sis
793f0b605c init: fix Tegra "APP" /system partition mounting
- thanks rootfan in https://github.com/topjohnwu/Magisk/issues/2063#issuecomment-573232567

Closes #2243
2020-02-01 01:09:12 +08:00
topjohnwu
ba55e2bc32 Backup proper magiskinit in A-only 2SI 2020-01-22 05:12:04 +08:00
topjohnwu
fafa92d44b Simplify rootfs persist mount 2020-01-08 22:42:54 +08:00
topjohnwu
12fda29280 Add support for pre-init custom sepolicy patches
Close #1685
2019-12-13 06:05:12 -05:00
topjohnwu
af060b3132 General QoL changes 2019-12-13 00:37:06 -05:00
topjohnwu
8c500709e4 Remove SAR compatibility mode 2019-12-12 03:25:48 -05:00
topjohnwu
08177c3dd8 Mount persist partition mirror pre-init 2019-12-09 04:09:23 -05:00
topjohnwu
4bb8ad19cf Small init refactoring 2019-12-06 12:02:34 -05:00