3 ms·

It is a security issue. The exposure is limited, but as folks point out; Apple forces people to build iOS binaries on machines running OSX. It'd be quite easy

It is a security issue. The exposure is limited, but as folks point out; Apple forces people to build iOS binaries on machines running OSX. It'd be quite easy to DoS commercial build services with this technique and there seems to be no way to stop it and detecting it can be pretty difficult. Depending on how the logging for such a server is structured, it may even be hard to tell which customer did it. This is also on the heels of a bug that's been discovered where it's possible to hang many types of system monitoring by abusing a race condition in the UNIX<->mach layer to block all process inspection tools on the OS. Given that Apple forces us to run OSX build servers, they should take the integrity of basic syscall checking seriously. And that totally ignores the chaos one person with an agenda (or poor project security) can cause if they get code that does this into Homebrew.

jakobegger 9y ago
There are a lot of ways to DoS a commercial build service. If you let people execute arbitrary code on your machine, you better have logging in place to know who is responsible if your machine crashes. I'd assume that most build farms build on VMs to avoid exactly this kind of problem -- building on bare metal seems pretty risky.
- oneweekwonder 9y ago
  > most build farms build on VMs Are one allowed to run macOS on a VM that is not apple hardware. Can you just buy macOS and run it on a vm, or is it a gray area?
  - ahakki 9y ago
    iirc macOS is only licensend to run on Apple hardware.
    - ctime 9y ago
      ..and only a single copy, it appears. These links are fun: https://github.com/kholia/OSX-KVM/blob/master/README.md https://github.com/kholia/OSX-KVM/blob/master/README.md http://www.contrib.andrew.cmu.edu/~somlo/OSXKVM/#sec_4 http://www.contrib.andrew.cmu.edu/~somlo/OSXKVM/#sec_4
  - princekolt 9y ago
    Well, either case you can still run the VMs on a real macOS machine. I assume crashing the VM should not crash the host, in most cases, unless there's a bug in the virtualization software, right?
  - wil421 9y ago
    You can absolutely run OSX on a VM and they even allow you to do it. Running it on a production sever is likely a gray area. People build Hackintoshes. I’ve personally run OSX VMs on both windows and macs and built a Hackintosh. Note I am saying OS X, haven’t done this since MacOS.
  - eridius 9y ago
    No you cannot run it on non-apple hardware. The SLA¹ for macOS 10.13 allows you to run up to 2 additional copies of macOS in virtual machines on your existing Mac hardware. So each Mac can run up to 3 copies of the OS in total. You may not run it on non-Mac hardware. ¹http://images.apple.com/legal/sla/docs/macOS1013.pdf http://images.apple.com/legal/sla/docs/macOS1013.pdf
copumpkin 9y ago
After looking at it more carefully, I'm not positive that it's a failure to check privileges, although the symptoms at the time made it look like that (literally logging an unprivileged process killing a privileged one). Rather, I think it's some sort of race. Anyway, I'm glad they fixed it now, but the response to our original bug submission didn't inspire a ton of confidence.

jakobegger 9y ago

There are a lot of ways to DoS a commercial build service. If you let people execute arbitrary code on your machine, you better have logging in place to know who is responsible if your machine crashes. I'd assume that most build farms build on VMs to avoid exactly this kind of problem -- building on bare metal seems pretty risky.

oneweekwonder 9y ago
> most build farms build on VMs Are one allowed to run macOS on a VM that is not apple hardware. Can you just buy macOS and run it on a vm, or is it a gray area?
- ahakki 9y ago
  iirc macOS is only licensend to run on Apple hardware.
  - ctime 9y ago
    ..and only a single copy, it appears. These links are fun: https://github.com/kholia/OSX-KVM/blob/master/README.md https://github.com/kholia/OSX-KVM/blob/master/README.md http://www.contrib.andrew.cmu.edu/~somlo/OSXKVM/#sec_4 http://www.contrib.andrew.cmu.edu/~somlo/OSXKVM/#sec_4
- princekolt 9y ago
  Well, either case you can still run the VMs on a real macOS machine. I assume crashing the VM should not crash the host, in most cases, unless there's a bug in the virtualization software, right?
- wil421 9y ago
  You can absolutely run OSX on a VM and they even allow you to do it. Running it on a production sever is likely a gray area. People build Hackintoshes. I’ve personally run OSX VMs on both windows and macs and built a Hackintosh. Note I am saying OS X, haven’t done this since MacOS.
- eridius 9y ago
  No you cannot run it on non-apple hardware. The SLA¹ for macOS 10.13 allows you to run up to 2 additional copies of macOS in virtual machines on your existing Mac hardware. So each Mac can run up to 3 copies of the OS in total. You may not run it on non-Mac hardware. ¹http://images.apple.com/legal/sla/docs/macOS1013.pdf http://images.apple.com/legal/sla/docs/macOS1013.pdf

copumpkin 9y ago

After looking at it more carefully, I'm not positive that it's a failure to check privileges, although the symptoms at the time made it look like that (literally logging an unprivileged process killing a privileged one). Rather, I think it's some sort of race. Anyway, I'm glad they fixed it now, but the response to our original bug submission didn't inspire a ton of confidence.