![]() When you’ve got a problem, don’t turn the safety systems off, as that’s just when you need them most. As with manually trying to patch macOS, this is a bit like smelling smoke in the building and responding by disabling the automatic sprinkler system in case it goes off. With SIP enforcing security on kernel extensions and the protection of hardening which accompanies notarization, some may now start recommending that SIP is turned off to work around problems with third-party kernel extensions or apps. Then the installer takes control of SIP, and when it’s finished should leave it turned on for you. If you think that, despite SIP being turned on, system files have become corrupted, the best solution is to reinstall them, either using the latest Combo updater for that version of macOS, or by reinstalling the whole of macOS. None of them, as far as I recall, was ever successful in tinkering in this way, and every case became rapidly worse once SIP was disabled and they started fiddling around with what should have been protected files. I have had a steady succession of advanced users who have turned SIP off and then tried to repair what they thought were corrupted components within macOS. SIP is also responsible for enforcing strict security restrictions on kernel extensions, which are now required to be both specially signed and notarized (for those signed from 7 April 2019 onwards).īefore these recent changes to SIP, disabling it was often recommended as a first step when attempting to fix problems in macOS which were blamed on damaged services or Property Lists. The mechanism which enforces SIP has also grown other functions over this period, and one which is becoming prominent in Mojave 10.14.5 and Catalina is the hardening required for notarization of third-party apps: Jeff Johnson revealed this late last year. This further enhances protection, and to ensure that apps and other software can still find the system files that they might rely on, Catalina uses a form of bi-directional symbolic link, termed a firmlink, to make it appear that the two new volumes are still one. Remember that in APFS, volumes within the same Container share free space, so you don’t have to worry about managing free space between them. This is changing with macOS 10.15 Catalina: when you install that, a new read-only volume is created and all those system files and folders are stored on that, set apart from Applications, your top-level Library folder, and user Home folders. Since El Capitan, Apple has steadily increased SIP’s coverage to include all its bundled apps and tools, but even in Mojave, they remain on the same volume as the rest of your startup folders, including the main Applications folder and user Home folders. The only way that a user can circumvent this is by turning SIP off when booted into Recovery mode (or from a bootable macOS installer) and using the csrutil command from there. SIP took all those system files out of reach of even the root user (consequently being referred to as rootless): using a combination of the nf file stored in /System/Library/Sandbox and the extended attribute, the contents of most system folders came under SIP’s protection. For once any malicious software gained access to the system, that Mac was doomed.īefore El Capitan, the only thing standing between system files and an attacker was the need to gain root privileges. Sometimes it was put down to disk errors, other times to an out-of-control extension or app, but we never wanted to think that it might have been deliberate. ![]() In earlier days of Mac OS X, it wasn’t uncommon for key system files to become damaged or corrupted. ![]() I hope in this article to convince you that it’s never safe to turn it off, and that Catalina makes that even more important with its new read-only system volume. ![]() Introduced relatively recently in El Capitan (2015), you’ll find various recommendations that to fix problems with macOS or even with some apps, you should turn SIP off first. System Integrity Protection – SIP – is one of the primary mechanisms which macOS uses to protect itself. ![]()
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