4 ms·

Aeah, how much more proprietary and strange are the Apple API's going to get? They'll have control over the entire vertical, and can put all kinds of undocument

Aeah, how much more proprietary and strange are the Apple API's going to get? They'll have control over the entire vertical, and can put all kinds of undocumented crap right in the silicon.

wscott 6y ago
even to the syscall level, like the MAP_JIT flag to mmap() https://developer.apple.com/documentation/bundleresources/entitlements/com_apple_security_cs_allow-jit https://developer.apple.com/documentation/bundleresources/en... not optional and requires special app entitlements to enable. So you are not going to write portable code that has a JIT without apple-special code.
- TwoBit 6y ago
  A JIT is a major potential source of malware enablement and thus a security consideration.
  - andrekandre 6y ago
    applogies if its an ignorant question but, if the os had proper access protections, even with a buffer overflow or other exploits to an app itself, how can that enable malware just by having a JIT?
    - saagarjha 6y ago
      It cannot; Apple's security policy towards third-party JITs is misguided. Such a feature is useful if you are interested in providing defense-in-depth for a JIT that you have taken effort to secure and would like stronger, hardware-backed mitigations for. The API should really be opt-in for the apps that want it–the real consumers of it are going to Chrome and Firefox.
    - lmm 6y ago
      JIT requires bypassing exploit mitigations e.g. W^X. JIT doesn't make an app that's already been subverted any more dangerous than it would otherwise be, but it makes it easier to exploit the app in the first place.
- saagarjha 6y ago
  And that JIT has additional considerations on Apple silicon, where there is specific hardware that needs to be taken into account: https://developer.apple.com/documentation/apple_silicon/porting_just-in-time_compilers_to_apple_silicon https://developer.apple.com/documentation/apple_silicon/port...
  - Klonoar 6y ago
    I ran into another quirk with MAP_JIT recently, but going the other direction in time. If you supported an older platform (High Sierra, which up until recently was... valid...), you would need to explicitly _not_ pass MAP_JIT into mmap there. It makes total sense once you find the bug, but it was also an easy one to overlook. Tracking that down was kind of annoying.

Aeah, how much more proprietary and strange are the Apple API's going to get? They'll have control over the entire vertical, and can put all kinds of undocumented crap right in the silicon.

wscott 6y ago

even to the syscall level, like the MAP_JIT flag to mmap() https://developer.apple.com/documentation/bundleresources/entitlements/com_apple_security_cs_allow-jit https://developer.apple.com/documentation/bundleresources/en... not optional and requires special app entitlements to enable. So you are not going to write portable code that has a JIT without apple-special code.

TwoBit 6y ago
A JIT is a major potential source of malware enablement and thus a security consideration.
- andrekandre 6y ago
  applogies if its an ignorant question but, if the os had proper access protections, even with a buffer overflow or other exploits to an app itself, how can that enable malware just by having a JIT?
  - saagarjha 6y ago
    It cannot; Apple's security policy towards third-party JITs is misguided. Such a feature is useful if you are interested in providing defense-in-depth for a JIT that you have taken effort to secure and would like stronger, hardware-backed mitigations for. The API should really be opt-in for the apps that want it–the real consumers of it are going to Chrome and Firefox.
  - lmm 6y ago
    JIT requires bypassing exploit mitigations e.g. W^X. JIT doesn't make an app that's already been subverted any more dangerous than it would otherwise be, but it makes it easier to exploit the app in the first place.
saagarjha 6y ago
And that JIT has additional considerations on Apple silicon, where there is specific hardware that needs to be taken into account: https://developer.apple.com/documentation/apple_silicon/porting_just-in-time_compilers_to_apple_silicon https://developer.apple.com/documentation/apple_silicon/port...
- Klonoar 6y ago
  I ran into another quirk with MAP_JIT recently, but going the other direction in time. If you supported an older platform (High Sierra, which up until recently was... valid...), you would need to explicitly _not_ pass MAP_JIT into mmap there. It makes total sense once you find the bug, but it was also an easy one to overlook. Tracking that down was kind of annoying.