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As for the safety, I guess it rewrite syscalls that would otherwise fail for lack of privileges. In a way, they have made an advanced version of the old fakero

• xtrapolate 8y ago
  > "I guess it rewrite syscalls that would otherwise fail for lack of privileges" That's not how access control works (on most systems). The system calls are still issued from a single process. If the gVisor process is running in the context of a non-privileged user, the system calls will fail regardless of the codepath.
  • dullgiulio 8y ago
    It rewrites the syscalls to make them succeed: reading a privileged file? Rewrite to read a non-privileged shadow file. Killing a privileged process? Return success without killing anything, etc. Whatever is not rewritten will fail in kernel: there is no security risk.
    • xtrapolate 8y ago
      > "It rewrites the syscalls to make them succeed" Imagine some applications expect the syscall to actually fail (ie. some odd way to test permissions). I fail to grasp how this is a strength. Pulling the rug from under applications is dangerous. You're in a direct battle with internal implementation specifics - you don't want to get into that as an abstraction layer. You don't want to tailor various hacks for specific applications.