[ovs-dev] unix domain socket permissions on freebsd

[Ben Pfaff]

According to _Unix Network Programming_, only the umask controls the
permissions of a Unix domain socket created by bind().  This makes it
difficult to correctly control permissions on sockets in a
multithreaded process, since the umask is not thread-specific.
Therefore, currently bind_unix_socket() in socket-util.c has a race.

On Linux, one can also affect the permissions of a Unix domain socket
by fchmoding the socket *before* calling bind().  Based on a glance at
the FreeBSD source, I don't think that this works on BSD.  Is there
another way to do it there?  (Does it work to fchmod the socket
post-bind?)  If not, we might have to add a fallback that forks off a
process, sets the umask, and binds the socket.

I guess FreeBSD and NetBSD could potentially differ here, too.

Thanks,

Ben.