DNS+chroot (Linux): no libraries needed in chroot cell !?!
Barrett Richardson
barrett at phoenix.aye.net
Mon Aug 16 15:24:55 UTC 1999
On 12 Aug 1999, Dr. Dorothea Muecke-Herzberg wrote:
> Hi there,
>
> has anyone tried to run named chrooted and can help me with my
> problems? (running Linux-2.2.6 on a Compaq Proliant1600 and
> bind-8.2.1)
>
> First:
> I did build named according to INSTALL. (No problems there,
> except if I want to build a statically linked version, but that's
> another story)
>
> For testing purposes I built a chroot environment without any
> libraries
> to see which ones are needed and started holelogd (for binding
> /jail/dns/root/dev/log to syslogd) and named:
> named -u named -g named -t /jail/dns/root
>
> To my utter surprise named started without any complaint !?!
> Here you see the excerpt of /var/log/messages:
>
> Jul 21 12:40:42 bastion named[2770]: starting. named 8.2.1
> Jul 20 14:50:08 GMT 1999 ^Iroot at bastion:/jail/src/dns/src/bin/named
> Jul 21 12:40:42 bastion named[2770]: hint zone "" (IN) loaded
> (serial0)
> .
> .
> Jul 21 12:40:42 bastion named[2770]: listening on [127.0.0.1].53 (lo)
> Jul 21 12:40:42 bastion named[2770]: Forwarding source address is
> [0.0.0.0].53
> Jul 21 12:40:42 bastion named[2771]: chrooted to /jail/dns/root
> Jul 21 12:40:42 bastion named[2771]: group = named
> Jul 21 12:40:42 bastion named[2771]: user = named
> Jul 21 12:40:42 bastion named[2771]: Ready to answer queries.
>
> First question: What is going on here? Why doesn't named need the
> shared libraries?
>
References to the shared libs were established before the chroot
occurred.
> _______________________
>
> Second:
> My second problem appears 45 min later. See /var/log/messages:
>
> Jul 21 13:28:02 bastion named[2937]: can't exec /usr/sbin/named-xfer:
> No such file or directory
>
> But there is an named-xfer in /jail/dns/root/usr/sbin (in /usr/sbin
> too!)!
Here is where the shared libs come in. I know the "No such file
for directory" message is a bit vague -- it may be more informative
if you throw libc.so into /jail/dns/root/usr/lib -- may even
spit out a message like "named-xfer: could not load shared library
libxx.so".
> According to the above logfile the chroot to /jail/dns/root worked
> fine.
>
> Second question: Has someone experienced the same? Can someone tell me
> what's wrong?
> ________________________
>
> Any help will be appreciated. Thanks in advance
>
> Dorothea
>
>
>
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