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Re: sys_chroot+sys_fchdir Fix

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To: Alan Cox <alan@...>
Cc: Bill Davidsen <davidsen@...>, majkls <majkls@...>, <bunk@...>, <linux-kernel@...>
Date: Wednesday, September 19, 2007 - 6:24 pm

> Normal users cannot use chroot() themselves so they can't use chroot to

I think Bill is right, that this is to fix a method that non-root 
processes can use to escape their chroot. The exploit, which is 
documented in chroot(2)*, is to chdir("..") your way out. Who'd have 
thought it? Only root can do that, but even that seems wrong. Chroot 
should be chroot and that should be the end of it.

It looks to me like Miloslav has found a bug, although I suspect there's 
a simpler solution because non-root is already prevented from escaping 
this way.

David

* In particular, the superuser can escape from a ‘chroot jail’ by doing 
‘mkdir foo; chroot foo; cd ..’.

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Messages in current thread:
sys_chroot+sys_fchdir Fix, majkls, (Wed Sep 19, 3:19 am)
Re: sys_chroot+sys_fchdir Fix, Alan Cox, (Wed Sep 19, 5:40 am)
Re: sys_chroot+sys_fchdir Fix, Bill Davidsen, (Wed Sep 19, 2:27 pm)
Re: sys_chroot+sys_fchdir Fix, Alan Cox, (Wed Sep 19, 2:45 pm)
Re: sys_chroot+sys_fchdir Fix, David Newall, (Wed Sep 19, 6:24 pm)
Re: sys_chroot+sys_fchdir Fix, Phillip Susi, (Fri Sep 21, 1:39 pm)
Re: sys_chroot+sys_fchdir Fix, Alan Cox, (Fri Sep 21, 2:10 pm)
Re: sys_chroot+sys_fchdir Fix, Phillip Susi, (Tue Sep 25, 4:53 pm)
Re: sys_chroot+sys_fchdir Fix, Al Viro, (Tue Sep 25, 8:23 pm)
Re: sys_chroot+sys_fchdir Fix, David Newall, (Wed Sep 26, 6:34 am)
Re: sys_chroot+sys_fchdir Fix, Christer Weinigel, (Wed Sep 26, 3:24 pm)
Re: sys_chroot+sys_fchdir Fix, David Newall, (Wed Sep 26, 5:19 pm)
Re: sys_chroot+sys_fchdir Fix, Christer Weinigel, (Thu Sep 27, 3:28 am)
Re: sys_chroot+sys_fchdir Fix, Theodore Tso, (Thu Sep 27, 7:23 am)
Re: sys_chroot+sys_fchdir Fix, Bill Davidsen, (Thu Sep 27, 10:36 am)
Re: sys_chroot+sys_fchdir Fix, David Newall, (Thu Sep 27, 9:06 pm)
Re: sys_chroot+sys_fchdir Fix, Adrian Bunk, (Wed Sep 26, 5:55 pm)
Re: sys_chroot+sys_fchdir Fix, David Newall, (Wed Sep 26, 7:35 pm)
Re: sys_chroot+sys_fchdir Fix, Adrian Bunk, (Wed Sep 26, 8:01 pm)
Re: sys_chroot+sys_fchdir Fix, David Newall, (Thu Sep 27, 2:42 am)
Re: sys_chroot+sys_fchdir Fix, Adrian Bunk, (Thu Sep 27, 2:53 am)
Re: sys_chroot+sys_fchdir Fix, Al Viro, (Wed Sep 26, 11:59 pm)
Re: sys_chroot+sys_fchdir Fix, Al Viro, (Wed Sep 26, 2:40 pm)
Re: sys_chroot+sys_fchdir Fix, Alan Cox, (Wed Sep 26, 7:21 am)
Re: sys_chroot+sys_fchdir Fix, David Newall, (Wed Sep 26, 7:22 am)
Re: sys_chroot+sys_fchdir Fix, Alan Cox, (Wed Sep 26, 7:38 am)
Re: sys_chroot+sys_fchdir Fix, David Newall, (Wed Sep 26, 7:56 am)
Re: sys_chroot+sys_fchdir Fix, Alan Cox, (Wed Sep 26, 10:10 am)
Re: sys_chroot+sys_fchdir Fix, David Newall, (Wed Sep 26, 12:54 pm)
Re: sys_chroot+sys_fchdir Fix, Alan Cox, (Wed Sep 26, 1:04 pm)
Re: sys_chroot+sys_fchdir Fix, David Newall, (Wed Sep 26, 1:18 pm)
Re: sys_chroot+sys_fchdir Fix, Alan Cox, (Wed Sep 26, 1:29 pm)
Re: sys_chroot+sys_fchdir Fix, David Newall, (Wed Sep 26, 1:28 pm)
Re: sys_chroot+sys_fchdir Fix, Chris Adams, (Wed Sep 26, 11:03 am)
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