SELinux Policy (Demo)
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Video Transcription
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>> Hey, Cybrarians.
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>> Welcome back to
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>> the Linux plus course here at Cybrary.
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I'm your instructor Rob Goelz.
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In today's lesson, we're going to
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be covering SELinux policy.
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Upon completion of today's lesson,
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you are going to be able to understand
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the concept of SELinux policies.
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We're going to use the command SC status to
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view extended SELinux properties
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and we're going to locate
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the SELinux root and
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targeted directories during our demo.
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SELinux sets three policy types.
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These are sometimes labeled as SELinux type
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in the configuration files
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that we'll look at here in a little bit.
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The targeted is the default policy type.
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It allows administrators to find
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what are called fine-grained contexts.
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It allows for something called type security,
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which restricts access based
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on specific types of contexts.
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For example, if you have an Apache file,
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it might have HTTPD_config_t,
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and that's this configuration context.
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It's specific to HTTPD.
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This is the only policy that's on the Linux plus exam.
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Make sure that you understand
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this one and understand it well.
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But for the purposes of just
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going through a few more of these,
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there are two other policy types.
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There is minimum, which supports
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a minimal or selected set of process objects.
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We're just going to look at
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certain objects that we're going to secure.
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This is not in the exam again,
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it's just included here as a reference.
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Then there's another thing called
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MLS or multilayer security.
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This is used by the DOD,
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the US Department of Defense.
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It uses the Bell-LaPadula model.
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It defines levels that are applied to objects
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with c0 being minimal,
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and c3 being top-secret.
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This is top-secret classified stuff.
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This is not a miss exam,
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but it will be on the CompTIA Security Plus.
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If you go into that direction,
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make sure you remember MLS.
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To view the SELinux policies that's configured,
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we can run the SE status command.
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The SE status also displays
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the mode and location of
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some important files like the SELinux root.
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Let's take a closer look at this command and
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the SELinux root directory with
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some demo time [NOISE].
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Here we are back in
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our CentOS environment and
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we're looking at CentOS because
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SELinux is installed here by default
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since CentOS 7 and RHEL 7.
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In order to see those extended properties,
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we can run SE status.
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What we're actually going to see here is
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that we're running and enforcing mode,
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current mode is enforcing and
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the loaded policy name here is targeted.
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But we can also see
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our SELinux root directory, which is SELinux.
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Let's go ahead and go there. We're going to go
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cd at c SELinux.
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Then if we do an ls_l, what do we see?
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We see a config file in here.
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Those are always good to look at.
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Let's do ls on config and here we go.
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We see SELinux equals enforcing.
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This is where the mode is set and then we see
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SELinux type equals targeted like I said earlier.
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When we look at the policy type,
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we're going to also sometimes see it abbreviated or
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annotated as being SELinux type
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and in this case, it's targeted.
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This file is where
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those settings are set to be persistent.
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There's one more directory we might want to look at
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here just so that we understand where this is stored.
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We can go to SELinux
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and then look at the targeted sub-directory here.
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If we do an ls_l in here,
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in here we can see the context and policy directories.
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This is where SELinux stores and
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records these things for its use.
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With that, we've reached the end of this lesson.
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In this lesson, we covered
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the concept of SELinux policies.
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We talked about using the SE status command
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to view those extended SELinux properties.
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Then we found where we can locate and
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examine the SELinux root directory.
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Thanks so much for being here.
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I look forward to seeing you in the next lesson.
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