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I am trying to outline how you would do this on Linux. I appreciate OpenBSD has different facilities, but this is like telling a Japanese chef that their techni

• ori_b 7y ago
  Linux has the facilities needed for this -- they've existed in POSIX for ages. Doing a better job of it would be nice, but the suggested approach seems like a pretty big regression. Unveil() is irrelevant to this discussion, because your program ideally has nothing in its namespace to unveil. Pledge() is a useful additional layer of protection, dropping access to things that can't be controlled through the file system -- but Linux has seccomp-bpf that fills the same role. It's also unnecessary for privilege separation: It wasn't implemented until about 2 decades after the methods I'm talking about were in widespread use. And not just in OpenBSD -- from what I remember, Solaris had a section on it in their programming manuals. The principle is simple: Start the program, acquire capabilities (ie, fds) needed to do the job. Then, drop the ability to request capabilities, drop root, and start processing untrusted user input.