Re: Loopback (dir->dir) mounting (NOT -o loop)

From: Pavel Machek (
Date: Thu Jun 01 2000 - 15:29:19 EST


> > If I'm an idiot and this can already be done somehow please belittle me, show
> > me the way.
> >
> > Otherwise, I'd like to hear thoughts about adding loop back mounting
> > to Linux. What I mean by this is directory to directory mounting like is
> > available in Solaris via lofs.
> mount -t bind old new

Ugh. And it works on normal user in 2.4.0!

There *have* to be some security implications of this.

Okay, this one:

Lets assume home and tmp are periodically backed up; there's quota on
them. I (the evil user) do

pavel@bug:/tmp$ ~/mount -t bind /proc delme2
pavel@bug:/tmp$ cd delme2/
pavel@bug:/tmp/delme2$ ls
1/ 114/ 43/ 91/ cmdline fs/
ksyms net/ sys/
100/ 119/ 45/ 93/ cpuinfo ide/
loadavg partitions sysvipc/
101/ 120/ 5/ 95/ devices
interrupts locks pci tty/
102/ 13/ 6/ 97/ dma iomem
meminfo scsi/ uptime

That will surely confuse hell out of the backup utility. It is
probably going to confuse autoclean.

Being able to do that is nice; but I feel it should be default to
root-only in 2.4.0.

I'm "In my country we have almost anarchy and I don't care."
Panos Katsaloulis describing me w.r.t. patents me at

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