Jailbreak

This is the process by which full execute and write access is obtained on all the partitions of the iPhone. It is done by patching /etc/fstab to mount the System partition as read-write. This is entirely different from an unlock. Jailbreaking is the first action that must be taken before things like unofficial activation (hacktivation), and unofficial unlocking can be applied.

The original jailbreak also included modifying the afc service (used by iTunes to access the filesystem) to give full filesystem access from root. This was later updated to create a new service (afc2) that allows access to the full filesystem.

Modern jailbreaks also include patching the kernel to get around code signing and other restrictions.

Exploits which were used in order to jailbreak (in chronological order)

1.0.2

• Restore Mode (iBoot had a command named cp, which had access to the whole filesystem)

1.1.1

• Symlinks (an upgrade jailbreak)
• libtiff exploit (Adapted from the PSP scene, used by Jailbreakme)

1.1.2

• Mknod (an upgrade jailbreak)

1.1.3 / 1.1.4

• Soft Upgrade (an upgrade jailbreak)
• Ramdisk Hack

Exploits which are used in order to jailbreak 2.0 and above

Userland (used for all devices)

• MobileBackup Copy Exploit + Incomplete Codesign Exploit + BPF_STX Kernel Write Exploit (together for untethered jailbreak)

iPhone / iPhone 3G / iPod Touch

• Pwnage and Pwnage 2.0 (together)

iPod Touch 2G

• ARM7 Go (used by tethered jailbreaks)
• 0x24000 Segment Overflow

iPhone 3GS

• iBoot Environment Variable Overflow (also uses the 0x24000 Segment Overflow to make it untethered on older devices)
• usb_control_msg(0x21, 2) Exploit (also uses the 0x24000 Segment Overflow to make it untethered on older devices)

iPod Touch 3g

• usb_control_msg(0x21, 2) Exploit (tethered only)