It's also a handy way to keep their stranglehold on iOS web browsers, forcing all to use webkit. How exactly they turn off JIT compiling and allow any javascript to run at all, I don't really understand, and I don't know what vulnerabilities they must be aware of in Safari's engine that could lead to unsandboxed code execution (although thinking about it, this seems to prove they're aware of something inherently unsafe there). But if their claim is along the lines that all JIT compilers are vulnerable, that's a strong case for never allowing V8 or any other engine in the app store.
But if their claim is along the lines that all JIT compilers are vulnerable, that's a strong case for never allowing V8 or any other engine in the app store.
I’m okay with this; I’ve always felt that dealing with the security issues of 3rd party rendering engines and JavaScript implementations is a valid reason to not allow them on iOS.
Since Apple is the platform vendor, at the end of the day, if there’s a vulnerability, it’s their responsibility, even if (in a hypothetical future) it’s Google’s or Mozilla’s JIT that allowed the the malware to be installed on a user's device.
Of course, since all browsers on iOS use WebKit and JavaScript Core, they all get Lockdown protection for free.
This lockdown mode means they can support those other browsers in a non-lockdown mode. All they have to do is have lockdown mode disable all non-webkit browsers.
