chcontext - chcontext allocates a new security context and executes a command in that context.
SYNTAX
chcontext [options] <command arguments>
DESCRIPTION
chcontext allocates a new security context and executes a command in that context.
By default, a new/unused context is allocated
OPTIONS
--cap CAP_NAME
Add a capability from the command. This option may be repeated several time. See /usr/include/linux/capability.h In general, this option is used with the --secure option. --secure removes most critical capabilities and --cap adds specific ones.
--cap !CAP_NAME
Remove a capability from the command. This option may be repeated several time. See /usr/include/linux/capability.h
--ctx num
Select the context. Only root in context 0 is allowed to select a specific context.
Context number 1 is special. It can see all processes in any contexts, but can't kill them though.
--disconnect
Start the command in background and make the process a child of process 1.
--domainname new_domainname
Set the domainname (NIS) in the new security context.
Use "none" to unset the domainname.
--flag
Set one flag in the new or current security context. The following flags are supported. The option may be used several time.
lock: The new process is trapped and can't use
chcontext anymore.
sched: The new process and its children will
share a common execution priority.
nproc: Limit the number of process in the
vserver according to ulimit setting.
Normally, ulimit is a per user thing.
With this flag, it becomes a per vserver
thing.
private: No one can join this security context
once created.
--hostname new_hostname
Set the hostname in the new security context.
This is needed because if you create a less privileged security context, it may be unable to change its hostname.
--secure
Remove all the capabilities to make a virtual server trustable.
--silent
Do not print the allocated context number.
Information about context is found in /proc/self/status
FILES
/usr/sbin/chcontext
EXAMPLES
# You must be root, running X.
# We start an xterm in another security context
/usr/sbin/chcontext xterm &
# We check, there is no xterm running, yet we can
# see it.
ps ax | grep xterm
# Are we running in security context 0
# We check the s_context line in /proc/self/status
cat /proc/self/status
# Ok we in security context 0
# Try the security context 1
/usr/sbin/chcontext --ctx 1 ps ax | grep xterm
# Ok, we see the xterm, we try to kill it
/usr/sbin/chcontext --ctx 1 killall xterm
# No, security context 1 can see, but can't kill
# let's find out in which security context this
# xterm is running
/usr/sbin/chcontext --ctx 1 ps ax | grep xterm
# Ok, this is PID XX. We need the security context
/usr/sbin/chcontext --ctx 1 cat /proc/XX/status
# We see the s_context, this is SS.
# We want to kill this process
/usr/sbin/chcontext --ctx SS killall xterm
Please contribute some, if you feel it's important.
AUTHORS
This Man page was written by Klavs Klavsen <kl@vsen.dk> and based upon the helpful output from the program itself and the documentation on the Virtual Server site <http://www.solucorp.qc.ca/miscprj/s_context.hc?prjstate=1&nodoc=0>
