SELinux is preventing zenity...

[Dominick Grift]

On Sun, Dec 20, 2009 at 09:25:58PM -0500, Steve Blackwell wrote:
> On Fri, 18 Dec 2009 10:11:53 +0100
> Dominick Grift <domg472 at gmail.com> wrote:
> 
> > On Thu, Dec 17, 2009 at 08:36:00PM -0500, Steve Blackwell wrote:
> > > I have a UPS that sends an SNMP trap when the main power goes out.
> > > I wrote my snmptrapd.conf file to execute a script when the trap is
> > > received. The script simply calls zenity to pop up a message.
> > > 
> > > Here's my problem. If I start snmptrapd from the command line
> > > everything works beautifully but if I have the system start it at
> > > boot time or via System->Administration->Services, the trap gets
> > > logged
> > 
> > Because when you start it manually it gets executed in the users
> > environment which is unrestricted/ unprotected in el5
> 
> OK, I see that now. I got a bit wrapped around the axel because
> snmptrapd sometimes creates a file (I'm not quite sure
> when) called /var/net-smpd/snmptrapd.conf and if I run
> # /etc/rc.d/init.d/snmptrapd restart 
> as root it gets created with a snmpd_var_lib_t type but if I just
> start snmptrapd from the command line as root it gets created with a
> different type and then the system can't restart snmptrapd because it
> doesn't have permission to write to that file.  ... I think...
> 
> > 
> > > in /var/log/messages but the zenity window doesn't get displayed
> > > and I get these SELinux messages in /var/log/messages.
> > > 
> > > SELinux is preventing the zenity from using potentially mislabeled
> > > files (XO)...
> > > 
> > > SELinux is preventing zenity (snmpd_t) "name_connect" to <Unknown>
> > > <xserver_port_t>...
> > > 
> > > I've looked at the ouput of
> > > 
> > > # ps -ef | grep snmptrapd
> > > 
> > > and it is identical in both cases so I don't understand why one
> > > works and the other doesn't. I tried
> > > 
> > > # cat /var/log/messages | audit2allow -m local
> > 
> > The avc denial gets logged to .:
> > 
> > ausearch -m avc -ts yesterday | grep snmpt_t | audit2allow -M mysnmp
> > | semodule -i mysnmp.pp
> 
> This was also confusing me because I had auditd turned off and so the
> avc denials are supposed to go to /var/log/messages but it seems that
> some still went to /var/log/audit/audit.log. 
> 
> Anyhow running this command helped in that I don't get any more avc
> denials logged but I still don't see my dialog popup. I'm going to try
> this again starting with a clean log.
> 
> I have a few questions if you have the time to answer them. 
> 
> I have been reading this:
> http://www.linuxtopia.org/online_books/getting_started_with_SELinux/index.html
> and this:
> http://www.linuxtopia.org/online_books/writing_SELinux_policy_guide/index.html
> which I found quite useful but they are way out of date. Is there
> anything comparable that is current?

I recently wrote a bit about the policy structure in Fedora 12 , that also applies to 11 and to some degree el5.

its here: http://82.197.205.60/~dgrift/stuff/Managing_a_SELinux_environment_with_Fedora_12.pdf

its not detailed though.
> 
> My understanding is that a .te is a policy configuration file, a text
> file and that a .pp file is a policy package, a binary file. Does
> the .te file get "compiled" into a .pp file and if so how does this
> happen?

the .te , .fc and .if files make a complete source policy module. yes. A binary representation of this (.pp) is what gets loaded "into the kernel"

This is done via the checkmodule and semodule_package commands. We usually use the installed /usr/share/selinux/devel/Makefile to do this (requires selinux-policy-devel on el5)

> I read that the policy directory for Fedora systems is
> /etc/security/selinux/src/policy
> but neither the RHEL5.4 system at work nor my Fedora 11 system at home

I think that is old (el4/fc4/5?)

> has such a directory and the only .te file is in 
> /usr/share/selinux/devel.
> Where is the accepted location to put .te files?
> 

.te files is source policy. It should not get installed. The only source policy file that can get installed is the .if source policy file. This file is kind of like a header file. It has shared policy that can be used by other modules to interact with that modules' type.

> Is there a way to "see" what a .pp file is doing? A disassembly of
> sorts. I'd like to look at some examples. There are plenty of .pp files
> in /etc/selinux/targeted/modules/active/modules.

The is not pp disassembler but the sesearch command can be used to query the installed policy. (part of setools)
> 
> Thanks,
> Steve
> > > 
> > > but that just produced a file that said:
> > > 
> > > module local 1.0;
> > > 
> > > and nothing else.
> > > 
> > > I'm running RHEL5.4 with SELinux in enforcing mode.
> > > 
> > > Any help would be appreciated.
> > > 
> > > Thanks,
> > > Steve
> > > 
> > > --
> > > fedora-selinux-list mailing list
> > > fedora-selinux-list at redhat.com
> > > https://www.redhat.com/mailman/listinfo/fedora-selinux-list
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