current implementation, jail neither virtualizes the Sys V IPC namespace,
nor provides inter-jail protections on IPC objects.
o Support for System V IPC can be enabled by setting jail.sysvipc_allowed=1
using sysctl.
o This is not the "real fix" which involves virtualizing the System V
IPC namespace, but prevents processes within jail from influencing those
outside of jail when not approved by the administrator.
Reported by: Paulo Fragoso <paulo@nlink.com.br>
TCP/IP (v4) sockets, and routing sockets. Previously, interaction
with IPv6 was not well-defined, and might be inappropriate for some
environments. Similarly, sysctl MIB entries providing interface
information also give out only addresses from those protocol domains.
For the time being, this functionality is enabled by default, and
toggleable using the sysctl variable jail.socket_unixiproute_only.
In the future, protocol domains will be able to determine whether or
not they are ``jail aware''.
o Further limitations on process use of getpriority() and setpriority()
by jailed processes. Addresses problem described in kern/17878.
Reviewed by: phk, jmg
``jail'', and move the set_hostname_allowed sysctl there, as well as
fixing a bug in the sysctl that resulted in jails being over-limited
(preventing them from reading as well as writing the hostname). Also,
correct some formatting issues, courtesy bde :-).
Reviewed by: phk
Approved by: jkh
This is a seriously beefed up chroot kind of thing. The process
is jailed along the same lines as a chroot does it, but with
additional tough restrictions imposed on what the superuser can do.
For all I know, it is safe to hand over the root bit inside a
prison to the customer living in that prison, this is what
it was developed for in fact: "real virtual servers".
Each prison has an ip number associated with it, which all IP
communications will be coerced to use and each prison has its own
hostname.
Needless to say, you need more RAM this way, but the advantage is
that each customer can run their own particular version of apache
and not stomp on the toes of their neighbors.
It generally does what one would expect, but setting up a jail
still takes a little knowledge.
A few notes:
I have no scripts for setting up a jail, don't ask me for them.
The IP number should be an alias on one of the interfaces.
mount a /proc in each jail, it will make ps more useable.
/proc/<pid>/status tells the hostname of the prison for
jailed processes.
Quotas are only sensible if you have a mountpoint per prison.
There are no privisions for stopping resource-hogging.
Some "#ifdef INET" and similar may be missing (send patches!)
If somebody wants to take it from here and develop it into
more of a "virtual machine" they should be most welcome!
Tools, comments, patches & documentation most welcome.
Have fun...
Sponsored by: http://www.rndassociates.com/
Run for almost a year by: http://www.servetheweb.com/
David Malone
Robert Watson
Poul-Henning Kamp
Peter Wemm