Messages in this thread | | | Subject | Re: can chroot be made safe for non-root? | From | Martin Josefsson <> | Date | 22 Oct 2002 17:55:13 +0200 |
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On Tue, 2002-10-22 at 16:15, Shaya Potter wrote:
> from vserver patch > > diff -rc2P linux-2.4.19/fs/namei.c linux-2.4.19ctx-14/fs/namei.c > *** linux-2.4.19/fs/namei.c Tue Aug 6 15:02:24 2002 > --- linux-2.4.19ctx-14/fs/namei.c Sun Oct 13 23:58:55 2002 > *************** > *** 153,156 **** > --- 153,165 ---- > umode_t mode = inode->i_mode; > > + /* > + A dir with permission bit all 0s is a dead zone for > + process running in a vserver. By doing > + chmod 000 /vservers > + you fix the "escape from chroot" bug. > + */ > + if ((mode & 0777) == 0 > + && S_ISDIR(mode) > + && current->s_context != 0) return -EACCES; > if (mask & MAY_WRITE) { > /* > > I don't think that will work, especially as it seems vserver's dont > nest.
This was just a quick and dirty fix to prevent root in a vserver from breaking out into the "real server", that's it. chroot() inside a vserver works exactly the same way as without vservers.
One negative sideeffect is that root in a vserver can't access any directory with all 0s in the permission bits. But that's better than having root in a vserver being able to go out into the "real server".
I'm not saying this is a very good solution but I think it at least does what it's supposed to do in a dirty way.
-- /Martin
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