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Getting started with electra (for developers)

Electra is an iOS 11 jailbreak for versions up to, and including, iOS 11.1.2.


Table of Contents

  1. Introduction
  2. Major changes in electra
  3. Getting development support

Introduction

Electra does things differently to most traditional jailbreaks, and the core of the jailbreak is based around a daemon called jailbreakd.

Major changes in electra

  • Substitute is used as the hooking framework instead of substrate
  • setuid(0); does not work out of the box (see below for how to use jailbreakd to patch setuid)
  • platform-application WILL NOT platformize your binary out of the box on electra

Using substitute

We provide a substrate-shim compatability layer, that works for most tweaks. Please report issues you have at the electra issues page and we'll look into them.

jailbreakd

Electra is a KPPLess jailbreak; this means that by nature, electra is not able to patch the kernel, therefore a jailbreak daemon is used in places where kernel patches would be. jailbreakd is a daemon that handles patching setuid for processes, platformising them, and handing certain entiltements out.

We provide a libjailbreak.dylib for interfacing with jailbreakd, and this is in /usr/lib/libjailbreak.dylib. All patches here will require dlopen()-ing the dylib, finding the appropiate symbol, and calling the respective function.

Setting uid 0

Here is sample code to patch setuid() with electra.

void patch_setuid() {
    void* handle = dlopen("/usr/lib/libjailbreak.dylib", RTLD_LAZY);
    if (!handle) 
        return;

    // Reset errors
    dlerror();
    typedef void (*fix_setuid_prt_t)(pid_t pid);
    fix_setuid_prt_t ptr = (fix_setuid_prt_t)dlsym(handle, "jb_oneshot_fix_setuid_now");
    
    const char *dlsym_error = dlerror();
    if (dlsym_error) 
        return;

    ptr(getpid());
}

This code is used in our cydia fork, and has been confirmed working. The code will call libjailbreakd, which will tell jailbreakd to patch setuid for our process. setuid(0); can now be called normally.

Platformizing a binary

In addition to signing your binary with the platform-application entiltement using ldid, you will also need to call jailbreakd to ensure your binary is correctly platformized. Sample code for this can be found below:

/* Set platform binary flag */
#define FLAG_PLATFORMIZE (1 << 1)

void platformize_me() {
    void* handle = dlopen("/usr/lib/libjailbreak.dylib", RTLD_LAZY);
    if (!handle) return;
    
    // Reset errors
    dlerror();
    typedef void (*fix_entitle_prt_t)(pid_t pid, uint32_t what);
    fix_entitle_prt_t ptr = (fix_entitle_prt_t)dlsym(handle, "jb_oneshot_entitle_now");
    
    const char *dlsym_error = dlerror();
    if (dlsym_error) return;
    
    ptr(getpid(), FLAG_PLATFORMIZE);
}

Getting development support

  • Join the /r/jailbreak discord, and ask for help in #development
  • Create a post on /r/jailbreakdevelopers
  • If neither of these solve your issues, open an issue on the the electra issues page
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