Re: 2.1.43 curious pipe-entries in / (root)

Jeremy Fitzhardinge (
Thu, 26 Jun 1997 10:56:47 +1000

Alan Cox wrote:
> > New code in 2.1.43 (see "get_pipe_inode" in "linux/fs/inode.c") puts
> > entries for anonymous pipes into the root directory. The 6-digit
> > number in the filename is the inode of the pipe.
> This is all well and good but has anyone considered the security implications
> and verified people cannot rm , open, or otherwise poke around with these
> pipes ?
> Also what if / is read only

I suspect they're just tacked into the namespace rather than given
actual entries. They appear to be mode 0600 of the user who created the
pipe, and you can open them. I suspect there's a problem if you manage
to get two priviledged things talking through a pipe you made (but I
guess if you keep a dup of one end, there's still the same problem).

You can't rename or unlink them (ENOENT - I guess the filesystem itself
doesn't know they're there).

As an aside, has anyone noticed that /proc/pid/fd for socket fds doesn't
give especially useful results? Perhaps there should be
/.anonymous-socket-* files too?

Also, does all this new namespace management stuff allow things like
constructed namespaces by concatenating directories (as in Plan 9)? Its
always been pretty tricky to work out how it might be done, but perhaps
its easier now.

I don't suppose anyone else mourns the loss of distinct readlink and
followlink operations...