Closing information leaks in jails?
bra at fsn.hu
Thu Aug 18 14:48:28 GMT 2005
I'm wondering about closing some information leaks in FreeBSD jails from
the "outside world".
Not that critical (depends on the application), but a simple user, with
restricted devfs in the jail (devfsrules_jail for example from
/etc/defaults/devfs.rules) can figure out the following:
- network interfaces related data, via ifconfig, which contains
everything, but the primary IP address of the interfaces. It seems that
alias IPs can be viewed:
bge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
media: Ethernet autoselect (100baseTX <full-duplex>)
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
inet 127.0.0.2 netmask 0xff000000
- the arp table via arp, which does contain the above interface
addresses. This can be used for example to detect other machines on the
same subnet, which communicate with the host machine.
- full dmesg output after boot and the kernel buffer when it overflows
(can contain sensitive information)
- information about geom providers (at least geom mirror list works)
- the list of the loaded kernel modules via kldstat
- some interesting information about the network related stuff via netstat
- information about configured swap space via swapinfo
- NFS related statistics via nfsstat
- a lot of interesting stuff via sysctl
and maybe more, I can't think of currently.
Are there any ways to close (some of) these?
Attila Nagy e-mail: Attila.Nagy at fsn.hu
Adopt a directory on our free software phone @work: +361 371 3536
server! http://www.fsn.hu/?f=brick cell.: +3630 306 6758
More information about the freebsd-security