I downloaded the source policy and i created this patch:
----------------
--- serefpolicy-3.6.12/policy/modules/kernel/corenetwork.te.in.old
2009-09-28 12:09:24.617041763 +0200
+++ serefpolicy-3.6.12/policy/modules/kernel/corenetwork.te.in 2009-09-28
12:09:51.410362006 +0200
@@ -261,6 +261,11 @@ network_interface(lo, lo,s0 - mls_system
typealias netif_t alias { lo_netif_t netif_lo_t };
')
+build_option(`enable_mls',`
+network_interface(eth0, eth0,s0 - mls_systemhigh)
+')
+
+
########################################
#
# Unconfined access to this module
-----------------
Then i recompiled the whole policy using the spec file, i installed it and i
relabeled the entire file system.
The problem is that i'm not able to use the new interfaces, for example
"corenet_tcp_sendrecv_eth0_if". When building a custom module that calls it,
the following message appears:
-----------------
Compiling targeted userdom module
/usr/bin/checkmodule: loading policy configuration from tmp/userdom.tmp
userdom.te":64:ERROR 'syntax error' at token 'corenet_tcp_sendrecv_eth0_if' on
line 151624:
corenet_tcp_sendrecv_eth0_if(sshdlow_t)
#line 64
/usr/bin/checkmodule: error(s) encountered while parsing configuration
make: *** [tmp/userdom.mod] Error 1
-----------------
In the patch described above i miss the line typealias netif.... because i
suppose that if eth0_netif_t is an alias of netif_t, allowing an access rule
for the last type means granting the privilege for all interfaces.
Lastly i have another question about the ssh server and its ability to set new
domains for processes of remote users.
I want to have two different servers, one which is able to set all possible
domains for the shell, another which have a capability to set only a subset of
domain. To accomplish this task i used the interface "ssh_server_template", i
copied from the file ssh.te all rules that involve the domain sshd_t and i
added the following lines:
-------------------
interface(`ssh_server_users_interaction',`
gen_require(`
type $1_t, shell_exec_t;
type $2;
')
allow $1_t $2: process transition;
allow $2 $1_t:process sigchld;
allow $1_t $2:process { siginh };
dontaudit $1_t $2:process { noatsecure };
')
-------------------
Is this correct or there's a way for that to be circumvented?
Thanks for replies.
On Saturday 26 September 2009 18:29:48 Dominick Grift wrote:
> On Sat, Sep 26, 2009 at 05:15:36PM +0200, Roberto Sassu wrote:
> > Hi all
> >
> > i want to create a set of rules that allow the administrator to decide
> > the network interfaces on which daemons can listen to.
> >
> > To do this i created a custom policy module to define the type
> > eth0_netif_t which is bound to the eth0 interface.
> >
> > type eth0_netif_t, netif_type;
> > typeattribute eth0_netif_t netif_type;
> >
> >
> > ifdef(`enable_mls',`
> >
> > gen_require(`type unlabeled_t;')
> > netifcon eth0 gen_context(system_u:object_r:eth0_netif_t,s0 -
> > mls_systemhigh) gen_context(system_u:object_r:unlabeled_t,s0 -
> > mls_systemhigh)
> >
> > ')
> >
> > Next, i executed the following command:
> >
> > semanage interface -a -t eth0_netif_t eth0
> >
> > Then, without adding extra rules i tried to start the sshd daemon on this
> > interface and the operation was successful. I see with the apol utility
> > that sshd is allowed to bind on the generic interface netif_t but not on
> > eth0_netif_t.
> >
> > How it's possible to explicitly grant the permission to listen on eth0
> > for each daemon which needs it?
>
> These types are declared in the corenetwork source policy, which is
> compiled into the base module. For you to be able to implement policy with
> regard to how domains can interact with network interface object type you
> would have to edit the policy. For example:
>
> This is from apache.te:
>
> corenet_tcp_sendrecv_all_if(httpd_t)
> corenet_udp_sendrecv_all_if(httpd_t)
>
> Which means that httpd_t can send and receive tcp and udp packets using all
> network interfaces. So these rule would have to be removed/replaced by
> rules that explicitly define how and which network interfaces httpd_t can
> access.
>
> This would have to be done for each domain that has access to network
> interfaces via the "all_if" interfaces.
>
> So if you really want to make this work, you should download the
> selinux-policy.src.rpm corresponding to the selinux-policy version that
> you currently have installed. Then extract the source rpm and prep the
> source ( apply the included patch(es) to the extracted included
> serefpolicy.tgz.
>
> Then you would have to declare your custom interface object type in
> corenetwork.te.in and remove the "all_if" interface calls from each module
> that calls it. Replace it with rules the you want to enforce. When you
> build the policy interfaces will be automatically created by the
> corenetwork module. You can call these interfaces instead of using "local
> policy"
>
> After you have modified the policy you would "clean the source" and
> repackage it (serefpolicy.tgz). Since you have already applies any
> included patches by redhat when you have "preparated the source" you no
> longer have to patch the source, thus you can remove any lines where it
> refers to 'patch' from the selinux-policy.spec that is included with the
> source rpm.
>
> Also "bump" the version in the spec file so that it can be installed
> without forcing installation.
>
> Then you would simply rebuild the selinux-policy.src.rpm using rpm-devtools
> (rpmbuild -ba selinux-policy.spec), and update your policy with rpm -Uvh
> selinux-policy*.rpm
>
> The problem with this method though is that from that point you are the
> maintainer of your implemented policy, meaning you can no longer blindly
> update from the redhat packages if you do not want your modification to be
> resetted.
>
> With EL5 this is not such a big problem since EL5 selinux-policy does not
> get updated very often.
>
> hth
>
> > Thanks in advance for replies.
> >
> > --
> > fedora-selinux-list mailing list
> > fedora-selinux-list@xxxxxxxxxx
> > https://www.redhat.com/mailman/listinfo/fedora-selinux-list
>
--
fedora-selinux-list mailing list
fedora-selinux-list@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/fedora-selinux-list
