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* CLONE_NEWNS and bind mounts to make "chroot" jail
@ 2008-03-01 17:05 Leibowitz, Michael
  2008-03-02  2:26 ` serge
  0 siblings, 1 reply; 6+ messages in thread
From: Leibowitz, Michael @ 2008-03-01 17:05 UTC (permalink / raw)
  To: linux-kernel

I have been trying to use the combination of CLONE_NEWNS and bind mounts
to create a better (than) chroot jail.  I wish to have the ability to
bind (ro will be possible in the future, I understand) certain
directories into the jail (perhaps /bin, /lib, /usr), but not have
parallel directories in the jail (no /etc, ..., /home). 

I have heard that this should be possible, but have yet to get a working
solution.

I have tried something analogous to:
chdir("/jail");
unshare(CLONE_NEWNS);
/* mount(8) syntax given for simplicity, but mount(2) used below */
mount --bind / /jail/old_root
mount --bind /jail/old_root/bin /jail/bin
mount --bind /jail/old_root/usr /jail/usr
mount --bind /jail/old_root/lib /jail/lib
mount --bind /jail /               # does nothing?
umount2("/old_root", MNT_DETACH);  # never happens.
exec("bin/sh");

When bin/sh runs, I can still see old_root from /jail and the bind of
/jail over / seems to have not done anything.  

Is it possible to create such a jail with bind mounts?  Is there a
recommended method for doing so?  Thank you for your time.

--
Michael Leibowitz
Software Engineer, UMG
Intel Corporation
michael.leibowitz at intel.com



^ permalink raw reply	[flat|nested] 6+ messages in thread

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2008-03-03 15:54     ` CLONE_NEWNS and bind mounts to make "chroot" jail Bodo Eggert
2008-03-01 17:05 Leibowitz, Michael
2008-03-02  2:26 ` serge
2008-03-03  6:56   ` Leibowitz, Michael
2008-03-04 21:45     ` serge
2008-03-05  6:23       ` Leibowitz, Michael

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