From 82c99e8de8f2ffef7d340fd7c1d9088367650eb5 Mon Sep 17 00:00:00 2001
From: Watson Sato <wsato@redhat.com>
Date: Mon, 10 May 2021 18:53:02 +0200
Subject: [PATCH]  Update and select seboolean rules for R67

Fix description of sebool_deny_execmem, and warning about possible
issues.
Add rationale to rules the SELinux booleans.
---
 controls/anssi.yml                            | 14 +++++++++---
 .../sebool_deny_execmem/rule.yml              | 22 ++++++++++++++-----
 .../sebool_selinuxuser_execheap/rule.yml      |  4 +++-
 .../sebool_selinuxuser_execstack/rule.yml     |  3 ++-
 4 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/controls/anssi.yml b/controls/anssi.yml
index 705f8e25aab..ef9356a6fea 100644
--- a/controls/anssi.yml
+++ b/controls/anssi.yml
@@ -967,10 +967,18 @@ controls:
       allow_execstack to off, forbids processes to make their stack executable;
       secure_mode_insmod to on, prohibits dynamic loading of modules by any process;
       ssh_sysadm_login to off, forbids SSH logins to connect directly in sysadmin role.
+    notes:
+      In RHEL, the SELinux boolean allow_execheap is renamed to selinuxuser_execheap, and the
+      boolean allow_execstack is renamed to selinuxuser_execstack. And allow_execmem is not
+      available, deny_execmem provides the same functionality.
+    automated: yes
     rules:
-    # Add rule for sebool allow_execheap
-    # Add rule for sebool allow_execmem
-    # Add rule for sebool allow_execstack
+    - var_selinuxuser_execheap=off
+    - sebool_selinuxuser_execheap
+    - var_deny_execmem=on
+    - sebool_deny_execmem
+    - var_selinuxuser_execstack=off
+    - sebool_selinuxuser_execstack
     - var_secure_mode_insmod=on
     - sebool_secure_mode_insmod
     - sebool_ssh_sysadm_login
diff --git a/linux_os/guide/system/selinux/selinux-booleans/sebool_deny_execmem/rule.yml b/linux_os/guide/system/selinux/selinux-booleans/sebool_deny_execmem/rule.yml
index f340ea4be11..e8453fbfb8d 100644
--- a/linux_os/guide/system/selinux/selinux-booleans/sebool_deny_execmem/rule.yml
+++ b/linux_os/guide/system/selinux/selinux-booleans/sebool_deny_execmem/rule.yml
@@ -2,14 +2,16 @@ documentation_complete: true
 
 prodtype: rhel7,rhel8,rhv4
 
-title: 'Disable the deny_execmem SELinux Boolean'
+title: 'Enable the deny_execmem SELinux Boolean'
 
 description: |-
     By default, the SELinux boolean <tt>deny_execmem</tt> is disabled.
-    If this setting is enabled, it should be disabled.
+    If this setting is disabled, it should be enabled.
     {{{ describe_sebool_disable(sebool="deny_execmem") }}}
 
-rationale: ""
+rationale: |-
+    Allowing user domain applications to map a memory region as both writable and
+    executable makes them more susceptible to data execution attacks.
 
 severity: medium
 
@@ -19,10 +21,20 @@ identifiers:
 
 references:
     anssi: BP28(R67)
-    
-{{{ complete_ocil_entry_sebool_disabled(sebool="deny_execmem") }}}
+
+{{{ complete_ocil_entry_sebool_enabled(sebool="deny_execmem") }}}
+
+warnings:
+    - general: |-
+        This rule doesn't come with a remediation, as enabling this SELinux boolean can cause
+        applications to malfunction, for example Graphical login managers and Firefox.
+    - functionality: |-
+        Proper function and stability should be assessed before applying enabling the SELinux boolean in production systems.
 
 template:
     name: sebool
     vars:
         seboolid: deny_execmem
+    backends:
+        bash: "off"
+        ansible: "off"
diff --git a/linux_os/guide/system/selinux/selinux-booleans/sebool_selinuxuser_execheap/rule.yml b/linux_os/guide/system/selinux/selinux-booleans/sebool_selinuxuser_execheap/rule.yml
index 45aa81a1223..7fedaab6130 100644
--- a/linux_os/guide/system/selinux/selinux-booleans/sebool_selinuxuser_execheap/rule.yml
+++ b/linux_os/guide/system/selinux/selinux-booleans/sebool_selinuxuser_execheap/rule.yml
@@ -6,10 +6,12 @@ title: 'Disable the selinuxuser_execheap SELinux Boolean'
 
 description: |-
     By default, the SELinux boolean <tt>selinuxuser_execheap</tt> is disabled.
+    When enabled this boolean is enabled it allows selinuxusers to execute code from the heap.
     If this setting is enabled, it should be disabled.
     {{{ describe_sebool_disable(sebool="selinuxuser_execheap") }}}
 
-rationale: ""
+rationale: |-
+    Disabling code execution from the heap blocks buffer overflow attacks.
 
 severity: medium
 
diff --git a/linux_os/guide/system/selinux/selinux-booleans/sebool_selinuxuser_execstack/rule.yml b/linux_os/guide/system/selinux/selinux-booleans/sebool_selinuxuser_execstack/rule.yml
index 2b20d0bfe4f..2e0b19f881d 100644
--- a/linux_os/guide/system/selinux/selinux-booleans/sebool_selinuxuser_execstack/rule.yml
+++ b/linux_os/guide/system/selinux/selinux-booleans/sebool_selinuxuser_execstack/rule.yml
@@ -10,7 +10,8 @@ description: |-
     to make their stack executable.
     {{{ describe_sebool_disable(sebool="selinuxuser_execstack") }}}
 
-rationale: ""
+rationale: |-
+    Disabling code execution from the stack blocks buffer overflow attacks.
 
 severity: medium