Commit Graph

26 Commits

Author SHA1 Message Date
topjohnwu
16e4c67992 Significantly broaden sepolicy.rule compatibility
Previously, Magisk uses persist or cache for storing modules' custom
sepolicy rules. In this commit, we significantly broaden its
compatibility and also prevent mounting errors.

The persist partition is non-standard and also critical for Snapdragon
devices, so we prefer not to use it by default.

We will go through the following logic to find the best suitable
non-volatile, writable location to store and load sepolicy.rule files:

Unencrypted data -> FBE data unencrypted dir -> cache -> metadata -> persist

This should cover almost all possible cases: very old devices have
cache partitions; newer devices will use FBE; latest devices will use
metadata FBE (which guarantees a metadata parition); and finally,
all Snapdragon devices have the persist partition (as a last resort).

Fix #3179
2020-11-02 23:20:38 -08:00
topjohnwu
0feab753fb Fix coding errors and minor changes 2020-10-28 04:17:34 -07:00
Leorize
d0b6318b90 init/mount: support for dm-verity verified root
This commit adds support for kernel initialized dm-verity on legacy SAR
devices.

Tested on a Pixel 2 XL with a kernel patch to initialize mappings
specified via the `dm=` kernel parameter even when an initramfs is used.
2020-10-27 03:47:50 -07:00
topjohnwu
966e23b846 magiskinit code tidy-up 2020-10-26 20:46:15 -07:00
topjohnwu
b73d5753f2 Minor code cleanups 2020-09-02 02:49:32 -07:00
classic-gentleman
0ed524f173 Test for NVIDIA/Tegra partition naming scheme first
Fixes https://github.com/topjohnwu/Magisk/issues/3014
2020-07-24 00:26:51 -07:00
topjohnwu
1e2f776b83 Move logging.hpp 2020-06-17 01:17:28 -07:00
topjohnwu
dbf8c41209 Force init to load fstab from file in 2SI
Patching DTBs is proven to be difficult and problematic as there are
tons of different formats out there. Adding support for all the formats
in magiskboot has been quite an headache in the past year, and it still
definitely does not cover all possible cases of them out there.

There is another issue: fake dt fstabs. Some super old devices do not
have device trees in their boot images, so some custom ROM developers
had came up with a "genius" solution: hardcode fstab entries directly
in the kernel source code and create fake device tree nodes even if
Android 10+ init can graciously take fstab files instead (-_-) 。。。

And there is YET another issue: DTBs are not always in boot images!
Google is crazy enough to litter DTBs all over the place, it is like
they cannot make up their minds (duh). This means the dt fstabs can be
either concatnated after the kernel (1), in the DTB partition (2), in
the DTBO partition (3), in the recovery_dtbo section in boot images (4),
or in the dtb section in boot images (5). FIVE f**king places, how can
anyone keep up with that!

With Android 10+ that uses 2 stage inits, it is crutual for Magisk to
be able to modify fstab mount points in order to let the original init
mount partitions for us, but NOT switch root and continue booting. For
devices using dt for early mount fstab, we used to patch the DTB at
install time with magiskboot. However these changes are permanent and
cannot be restored back at reinstallation.

With this commit, Magisk will read dt fstabs and write them to ramdisk
at boot time. And in that case, the init binary will also be patched
to force it to NEVER use fstabs in device-tree. By doing so, we can
unify ramdisk based 2SI fstab patching as basically we are just patching
fstab files. This also means we can manipulate fstab whatever Magisk
needs in the future without the need to going through the headache that
is patching DTBs at installation.
2020-05-04 02:21:51 -07:00
topjohnwu
0c99c4d93f More complete support for fstab in dt 2020-05-03 22:49:54 -07:00
topjohnwu
e219867cdf Hijack another binary for 2nd stage
Instead of using ptrace hacks, use another hack instead :D
2020-04-19 22:15:12 -07:00
topjohnwu
d959c35723 Make cleaner mount info 2020-04-18 18:50:25 -07:00
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