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LiveContainer Architecture Overview

Project structure​

Main executable​

  • Core of LiveContainer
  • Contains the logic of setting up guest environment and loading guest app.
  • If no app is selected, it loads LiveContainerSwiftUI.

LiveContainerSwiftUI​

  • SwiftUI rewrite of LiveContainerUI (by @hugeBlack)
  • Lanaguage file Localizable.xcstrings is in here for multilingual support. To help us translate LiveContainer, please visit our crodwin project

TweakLoader​

  • A simple tweak injector, which loads CydiaSubstrate and load tweaks.
  • Injected to every app you install in LiveContainer.

AltStoreTweak (Deprecated)​

  • The tweak that got injected into SideStore/AltStore to retrieve certificate from it everytime it launches.

ZSign​

  • The app signer shipped with LiveContainer.
  • Originally made by zhlynn.
  • LiveContainer uses Feather's version of ZSign modified by khcrysalis.
  • Changes are made to meet LiveContainer's need.

How does it work?​

Patching guest executable​

  • Patch __PAGEZERO segment:
    • Change vmaddr to 0xFFFFC000 (0x100000000 - 0x4000)
    • Change vmsize to 0x4000
  • Change MH_EXECUTE to MH_DYLIB.
  • Inject a load command to load TweakLoader.dylib

Patching @executable_path​

  • Call _NSGetExecutablePath with an invalid buffer pointer input -> SIGSEGV
  • Do some magic stuff to overwrite the contents of executable_path.

Patching NSBundle.mainBundle​

  • This property is overwritten with the guest app's bundle.

Bypassing Library Validation​

  • JIT is optional to bypass codesigning. In JIT-less mode, all executables are signed so this does not apply.
  • Derived from Restoring Dyld Memory Loading

dlopening the executable​

  • Call dlopen with the guest app's executable
  • TweakLoader loads all tweaks in the selected folder
  • Find the entry point
  • Jump to the entry point
  • The guest app's entry point calls UIApplicationMain and start up like any other iOS apps.

Multi-Account support & Keychain Semi-Separation​

128 keychain access groups are created and LiveContainer allocates them randomly to each container of the same app. So you can create 128 container with different keychain access groups.

Limitations​

  • Entitlements from the guest app are not applied to the host app. This isn't a big deal since sideloaded apps requires only basic entitlements.
  • App Permissions are globally applied.
  • Guest app containers are not sandboxed. This means one guest app can access other guest apps' data.
  • App extensions aren't supported. they cannot be registered because: LiveContainer is sandboxed, SpringBoard doesn't know what apps are installed in LiveContainer, and they take up App ID.
  • Multitasking can be achieved by using multiple LiveContainer and the multitasking feature. However, physical keyboard may not work for apps in multitasking mode.
  • Remote push notification might not work. If you have a paid developer account then you don't even have to use LiveContainer
  • Querying custom URL schemes might not work(?)