Adding binaries to the restored system

Modifying the RootFS after restore

After a successful restore, you might want to add your binaries on the system.

Mount the disk image

# attach
hdiutil attach -imagekey diskimage-class=CRawDiskImage -blocksize 4096 nvme.1

# enable ownership
sudo diskutil enableownership /Volumes/System

# mount with RW
mount -urw /Volumes/System

Rename snapshot

For every installation, iOS will create a snapshot (com.apple.os.update-*) for the RootFS and will always boot from it.

For filesystem changes to show up, we need to rename that snapshot so that iOS doesn't boot from it.

Open Disk Utility, select the System disk image (be careful to not rename the snapshot of the host), rename the only APFS snapshot to orig-fs. Accept the warning.

Eject the disk:

hdiutil eject /Volumes/System

Then follow the steps to remount the disk. You only need to rename the snapshot ONCE.

Add precompiled system binaries

sudo rsync -av strap/ /Volumes/System

Create trustcache

This step is no longer needed as we now patch AMFI

Bundled trustcache

python3 qemu-t8030-tools/bootstrap_scripts/asn1trustcachedecode.py Firmware/038-44337-083.dmg.trustcache Firmware/038-44337-083.dmg.trustcache.out
python3 qemu-t8030-tools/bootstrap_scripts/dump_trustcache.py Firmware/038-44337-083.dmg.trustcache.out | grep cdhash | cut -d' ' -f2 > tchashes

Create trustcache for system binaries

for filename in $(find strap/  -type f); do jtool2 --sig $filename 2>/dev/null; done | grep CDHash | cut -d' ' -f6 | cut -c 1-40 >> ./tchashes

Serialize trustcache

python3 qemu-t8030-tools/bootstrap_scripts/create_trustcache.py tchashes static_tc

Configure LaunchDaemons

Either use setup-ios/launchd.plist, or customize it from iOS firmware as follows.

Copy /Volumes/System/System/Library/xpc/launchd.plist to somewhere else to work with.
Convert to xml1 format: plutil -convert xml1 /path/to/launchd.plist
Use Xcode or your preferred xml editor
- Remove all entries in LaunchDaemons (may be optional, add wdt=-1 to the boot args if you do this)
- Add an entry for bash in LaunchDaemons

		<key>/System/Library/LaunchDaemons/bash.plist</key>
		<dict>
			<key>EnablePressuredExit</key>
			<false/>
			<key>Label</key>
			<string>com.apple.bash</string>
			<key>POSIXSpawnType</key>
			<string>Interactive</string>
			<key>ProgramArguments</key>
			<array>
				<string>/bin/bash</string>
			</array>
			<key>RunAtLoad</key>
			<true/>
			<key>StandardErrorPath</key>
			<string>/dev/console</string>
			<key>StandardInPath</key>
			<string>/dev/console</string>
			<key>StandardOutPath</key>
			<string>/dev/console</string>
			<key>Umask</key>
			<integer>0</integer>
			<key>UserName</key>
			<string>root</string>
		</dict>

Copy back

sudo cp /path/to/launchd.plist /Volumes/System/System/Library/xpc/launchd.plist

Unmount the disk image

hdiutil detach /Volumes/System

Add a new binary to firmware

Build binary - require Xcode on macOS

xcrun -sdk iphoneos clang -arch arm64 -mcpu=apple-a13 -o hello hello.c

Then sign the binary

codesign -f -s - hello

Copy binary to firmware

# attach image
hdiutil attach -imagekey diskimage-class=CRawDiskImage -blocksize 4096 nvme.1

# enable ownership
sudo diskutil enableownership /Volumes/System

# mount with RW
mount -urw /Volumes/System

Then copy the signed binary to image

sudo cp hello /Volumes/System/bin

Also copy the binary to the local strap directory

cp hello strap/bin

Re-generate trustcache