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7.4. Configuration Examples

7.4.1. Setting up CVS

This example describes a simple CVS setup and an SELinux configuration which allows remote access. Two hosts are used in this example; a CVS server with a host name of cvs-srv with an IP address of 192.168.1.1 and a client with a host name of cvs-client and an IP address of 192.168.1.100. Both hosts are on the same subnet (192.168.1.0/24). This is an example only and assumes that the cvs and xinetd packages are installed, that the SELinux targeted policy is used, and that SELinux is running in enforced mode.
This example will show that even with full DAC permissions, SELinux can still enforce policy rules based on file labels and only allow access to certain areas that have been specifically labeled for access by CVS.

Note

Steps 1-9 should be performed on the CVS server, cvs-srv.
  1. This example requires the cvs and xinetd packages. Run the rpm -q cvs command to see if the cvs package is installed. If it is not installed, run the following command as the root user to install cvs: 
    ~]# yum install cvs
    Run the rpm -q xinetd command to see if the xinetd package is installed. If it is not installed, run the following command as the root user to install xinetd: 
    ~]# yum install xinetd
  2. Create a group named CVS. This can be done via the groupadd CVS command as the root user, or by using the system-config-users tool.
  3. Create a user with a user name of cvsuser and make this user a member of the CVS group. This can be done using the system-config-users tool.
  4. Edit the /etc/services file and make sure that the CVS server has uncommented entries looking similar to the following: 
    cvspserver	2401/tcp			# CVS client/server operations
cvspserver	2401/udp			# CVS client/server operations
  5. Create the CVS repository in the root area of the file system. When using SELinux, it is best to have the repository in the root file system so that recursive labels can be given to it without affecting any other subdirectories. For example, as the root user, create a /cvs/ directory to house the repository: 
    [root@cvs-srv]# mkdir /cvs
  6. Give full permissions to the /cvs/ directory to all users: 
    [root@cvs-srv]# chmod -R 777 /cvs

    Warning

    This is an example only and these permissions should not be used in a production system.
  7. Edit the /etc/xinetd.d/cvs file and make sure that the CVS section is uncommented and configured to use the /cvs/ directory. The file should look similar to: 
    service cvspserver
{
	disable	= no
	port			= 2401
	socket_type		= stream
	protocol		= tcp
	wait			= no
	user			= root
	passenv			= PATH
	server			= /usr/bin/cvs
	env			= HOME=/cvs
	server_args		= -f --allow-root=/cvs pserver
#	bind			= 127.0.0.1
  8. Start the xinetd daemon by running the service xinetd start command as the root user.
  9. Add a rule which allows inbound connections using TCP on port 2401 by using the system-config-firewall tool.
  10. As the cvsuser user, run the following command: 
    [cvsuser@cvs-client]$ cvs -d /cvs init
  11. At this point, CVS has been configured but SELinux will still deny logins and file access. To demonstrate this, set the $CVSROOT variable on cvs-client and try to log in remotely. The following step should be performed on cvs-client: 
    [cvsuser@cvs-client]$ export CVSROOT=:pserver:cvsuser@192.168.1.1:/cvs
[cvsuser@cvs-client]$
[cvsuser@cvs-client]$ cvs login
Logging in to :pserver:cvsuser@192.168.1.1:2401/cvs
CVS password: ********
cvs [login aborted]: unrecognized auth response from 192.168.100.1: cvs pserver: cannot open /cvs/CVSROOT/config: Permission denied
    SELinux has blocked access. In order to get SELinux to allow this access, the following step should be performed on cvs-srv:
  12. Change the context of the /cvs/ directory as the root user in order to recursively label any existing and new data in the /cvs/ directory, giving it the cvs_data_t type: 
    [root@cvs-srv]# semanage fcontext -a -t cvs_data_t '/cvs(/.*)?'
[root@cvs-srv]# restorecon -R -v /cvs
  13. The client, cvs-client should now be able to log in and access all CVS resources in this repository: 
    [cvsuser@cvs-client]$ export CVSROOT=:pserver:cvsuser@192.168.1.1:/cvs
[cvsuser@cvs-client]$
[cvsuser@cvs-client]$ cvs login
Logging in to :pserver:cvsuser@192.168.1.1:2401/cvs
CVS password: ********
[cvsuser@cvs-client]$