[throwaway7356]

> Unix domain sockets are just files, so they have an owner, group and mode bits. The answer to "who is potentially allowed to run a differently-privileged command?" is just `ls -l /path/to.sock`.

Yeah, except that is not true. To quote unix(7):

       On Linux, connecting to a stream socket object requires write permission on that socket; sending
       a datagram to a datagram socket likewise requires write permission on that socket.   POSIX  does
       not make any statement about the effect of the permissions on a socket file, and on some systems
       (e.g.,  older  BSDs),  the socket permissions are ignored.  Portable programs should not rely on
       this feature for security.

So s6 just has a wide, easily exploitable security hole there. Or is not portable, contrary to its claims.

[sigil]

Lol okay man. Maybe if you're running FreeBSD 4.2 or HP-UX or some BSD derivative from the 90s. All unix systems from about 2000 on will honor unix domain socket permissions.