Re: How to (or should I?) change unconfined_u to system_u for a file

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On 7/14/2015 2:33 PM, Simon Sekidde wrote:

----- Original Message -----
From: "Stephen Smalley" <sds@xxxxxxxxxxxxx>
To: "Jeff Boyce" <jboyce@xxxxxxxxxxxxxxx>, "SELinux Fedora List" <selinux@xxxxxxxxxxxxxxxxxxxxxxx>
Sent: Tuesday, July 14, 2015 1:41:22 PM
Subject: Re: How to (or should I?) change unconfined_u to system_u for a file

On 07/14/2015 01:04 PM, Jeff Boyce wrote:
Greetings -

     I essentially have two questions here.  First, I have a file that
needs the context changed and I don't have a clear understanding of the
proper syntax that should be used.  Second, after doing some additional
reading through the SELinux manual and some Google searching, I realized
that I may be taking the wrong approach with this file.  Then I ran
across Dan Walsh's blog dated April 23, 2013 (Subject: What is the
differences between user_home_dir_t and user_home_t) and realize that I
am likely not doing something the appropriate way.  So I am looking for
someone to educate me on my error, the risks involved, and the proper
approach I should be using.

The issue:  I have two shell files run by cron that rsync our file
server directories to two backup servers, one on-site (Bison) and one
off-site.  The on-site cron has worked fine for years.  I just setup the
off-site cron and it is blocked by SELinux.  Looking at the context of
the files, the one that works is listed as system_u, while the one that
fails is listed as unconfined_u.  So my first question is, what is the
proper syntax for changing the context of the second file so that it
matches the first one.

[root@sequoia home]# pwd
/home
[root@sequoia home]# ls -lZ | grep RsyncS
-rwxr--r--. root    root    system_u:object_r:home_root_t:s0
RsyncSequoiaToBison.sh
-rwxr--r--. root    root    unconfined_u:object_r:home_root_t:s0
RsyncSequoiaToOffsite.sh
chcon --reference=RsyncSequoiaToBison.sh RsyncSequoiaToOffsite.sh

Looking from a wider perspective, I have these shell files located in
/home.  I am speculating now that for my objective, this might not be
the appropriate location for them, and is probably why SELinux is
blocking the new one I created for the off-site backup. So my second
question is more philosophical regarding what should be the location for
a shell file that is used by cron to rsync our files to a backup server.

What AVCs do you show for the new file?

     Thanks, and please cc me directly as I only receive the daily digest
from the mailing list.

Jeff

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Here is the raw AVC for the denial on the new file. Maybe my initial interpretation is wrong. I am open to being educated.

Raw Audit Messages
type=AVC msg=audit(1436888672.587:632188): avc: denied { execute } for pid=3240 comm="rsync" name="ssh" dev=vda2 ino=159011 scontext=system_u:system_r:rsync_t:s0 tcontext=system_u:object_r:ssh_exec_t:s0 tclass=file

type=SYSCALL msg=audit(1436888672.587:632188): arch=x86_64 syscall=execve success=no exit=EACCES a0=7fff9ec4332f a1=7fff9ec43460 a2=7fff9ec46620 a3=7f6741bba9d0 items=0 ppid=3239 pid=3240 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=4294967295 comm=rsync exe=/usr/bin/rsync subj=system_u:system_r:rsync_t:s0 key=(null)

Regarding Stephens response earlier, I was not familiar with the --reference= option for chcon, but since chcon does not survive a relabel, I am looking for a persistent change (and was expecting something for semanage fcontext). The last thing I need it to have this re-occur months later, with no connection back to this event.

Thanks.

--

Jeff Boyce, CF
Meridian Environmental
2136 Westlake Ave. North
Seattle, WA  98109
206-522-8282
www.meridianenv.com

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