Updated audit rules for arch

Signed-off-by: Mark Bolwell <mark.bollyuk@gmail.com>

tasks/auditd.yml

@@ -1,17 +1,30 @@
 ---
 
-- name: POST | AUDITD | Apply auditd template will for section 4.1.3 - only required rules will be added | stat file
+# Since auditd rules are dependent on syscalls and syscall tables are architecture specific,
+# we need to update the auditd rules depending on the architecture of the system.
+# This task passed the syscalls table to the auditd template and updates the auditd rules
+
+- name: "POST | AUDITD | Set supported_syscalls variable"
+  ansible.builtin.shell: ausyscall --dump |  awk  '{print $2}'
+  changed_when: false
+  failed_when: discovered_auditd_syscalls.rc not in [ 0, 1 ]
+  register: discovered_auditd_syscalls
+
+- name: POST | AUDITD | Apply auditd template will for section 6.3.3 - only required rules will be added | stat file
   ansible.builtin.stat:
     path: /etc/audit/rules.d/99_auditd.rules
   register: discovered_auditd_rules_file
 
-- name: POST | AUDITD | Apply auditd template will for section 4.1.3 - only required rules will be added | setup file
+- name: POST | Apply auditd template for section 6.3.3.x
+  when: update_audit_template
+  vars:
+    supported_syscalls: "{{ discovered_auditd_syscalls.stdout_lines }}"
   ansible.builtin.template:
     src: audit/99_auditd.rules.j2
     dest: /etc/audit/rules.d/99_auditd.rules
     owner: root
     group: root
-    mode: '0640'
+    mode: 'u-x,go-wx'
   diff: "{{ discovered_auditd_rules_file.stat.exists }}"  # Only run diff if not a new file
   register: discovered_auditd_rules_template_updated
   notify:

templates/audit/99_auditd.rules.j2

@@ -9,20 +9,40 @@
 -w /etc/sudoers.d -p wa -k scope
 {% endif %}
 {% if rhel9cis_rule_6_3_3_2 %}
--a always,exit -F arch=b64 -C euid!=uid -F auid!=unset -S execve -k user_emulation
--a always,exit -F arch=b32 -C euid!=uid -F auid!=unset -S execve -k user_emulation
+{% set syscalls = ["execve"] %}
+{% set arch_syscalls = [] %}
+{% for syscall in syscalls  %}
+{% if syscall in supported_syscalls %}
+{{ arch_syscalls.append( syscall) }}
+{% endif %}
+{% endfor %}
+-a always,exit -F arch=b64 -C euid!=uid -F auid!=unset -S {{ arch_syscalls|join(',') }} -k user_emulation
+-a always,exit -F arch=b32 -C euid!=uid -F auid!=unset -S {{ arch_syscalls|join(',') }} -k user_emulation
 {% endif %}
 {% if rhel9cis_rule_6_3_3_3 %}
 -w {{ rhel9cis_sudolog_location }} -p wa -k sudo_log_file
 {% endif %}
 {% if rhel9cis_rule_6_3_3_4 %}
--a always,exit -F arch=b64 -S adjtimex,settimeofday,clock_settime -k time-change
--a always,exit -F arch=b32 -S adjtimex,settimeofday,clock_settime -k time-change
+{% set arch_syscalls = [] %}
+{% for syscall in syscalls  %}
+{% if syscall in supported_syscalls %}
+{{ arch_syscalls.append( syscall) }}
+{% endif %}
+{% endfor %}
+-a always,exit -F arch=b64 -S {{ arch_syscalls|join(',') }} -k time-change
+-a always,exit -F arch=b32 -S {{ arch_syscalls|join(',') }} -k time-change
 -w /etc/localtime -p wa -k time-change
 {% endif %}
 {% if rhel9cis_rule_6_3_3_5 %}
--a always,exit -F arch=b64 -S sethostname,setdomainname -F key=system-locale
--a always,exit -F arch=b32 -S sethostname,setdomainname -F key=system-locale
+{% set syscalls = ["sethostname","setdomainname"] %}
+{% set arch_syscalls = [] %}
+{% for syscall in syscalls  %}
+{% if syscall in supported_syscalls %}
+{{ arch_syscalls.append( syscall) }}
+{% endif %}
+{% endfor %}
+-a always,exit -F arch=b64 -S {{ arch_syscalls|join(',') }}  -k system-locale
+-a always,exit -F arch=b32 -S {{ arch_syscalls|join(',') }}  -k system-locale
 -w /etc/issue -p wa -k system-locale
 -w /etc/issue.net -p wa -k system-locale
 -w /etc/hosts -p wa -k system-locale
@@ -35,10 +55,17 @@
 {% endfor %}
 {% endif %}
 {% if rhel9cis_rule_6_3_3_7 %}
--a always,exit -F arch=b64 -S creat,open,openat,truncate,ftruncate -F exit=-EACCES -F auid>={{ prelim_min_int_uid }} -F auid!=unset -k access
--a always,exit -F arch=b64 -S creat,open,openat,truncate,ftruncate -F exit=-EPERM -F auid>={{ prelim_min_int_uid }} -F auid!=unset -k access
--a always,exit -F arch=b32 -S creat,open,openat,truncate,ftruncate -F exit=-EACCES -F auid>={{ prelim_min_int_uid }} -F auid!=unset -k access
--a always,exit -F arch=b32 -S creat,open,openat,truncate,ftruncate -F exit=-EPERM -F auid>={{ prelim_min_int_uid }} -F auid!=unset -k access
+{% set syscalls = ["creat","open","openat","truncate","ftruncate"] %}
+{% set arch_syscalls = [] %}
+{% for syscall in syscalls  %}
+{% if syscall in supported_syscalls %}
+{{ arch_syscalls.append( syscall) }}
+{% endif %}
+{% endfor %}
+-a always,exit -F arch=b64 -S {{ arch_syscalls|join(',') }} -F exit=-EACCES -F auid=>{{ prelim_min_int_uid }} -F auid!=unset -k access
+-a always,exit -F arch=b64 -S {{ arch_syscalls|join(',') }} -F exit=-EPERM -F auid=>{{ prelim_min_int_uid }} -F auid!=unset -k access
+-a always,exit -F arch=b32 -S {{ arch_syscalls|join(',') }} -F exit=-EACCES -F auid=>{{ prelim_min_int_uid }} -F auid!=unset -k access
+-a always,exit -F arch=b32 -S {{ arch_syscalls|join(',') }} -F exit=-EPERM -F auid=>{{ prelim_min_int_uid }} -F auid!=unset -k access
 {% endif %}
 {% if rhel9cis_rule_6_3_3_8 %}
 -w /etc/group -p wa -k identity
@@ -51,16 +78,66 @@
 -w /etc/pam.d -p wa -k identity
 {% endif %}
 {% if rhel9cis_rule_6_3_3_9 %}
--a always,exit -F arch=b64 -S chmod,fchmod,fchmodat -F auid>={{ prelim_min_int_uid }} -F auid!=unset -F key=perm_mod
--a always,exit -F arch=b64 -S chown,fchown,lchown,fchownat -F auid>={{ prelim_min_int_uid }} -F auid!=unset -F key=perm_mod
--a always,exit -F arch=b32 -S chmod,fchmod,fchmodat -F auid>={{ prelim_min_int_uid }} -F auid!=unset -F key=perm_mod
--a always,exit -F arch=b32 -S lchown,fchown,chown,fchownat -F auid>={{ prelim_min_int_uid }} -F auid!=unset -F key=perm_mod
--a always,exit -F arch=b64 -S setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F auid>={{ prelim_min_int_uid }} -F auid!=unset -F key=perm_mod
--a always,exit -F arch=b32 -S setxattr,lsetxattr,fsetxattr,removexattr,lremovexattr,fremovexattr -F auid>={{ prelim_min_int_uid }} -F auid!=unset -F key=perm_mod
+{% set syscalls = ["chmod","fchmod","fchmodat"] %}
+{% set arch_syscalls = [] %}
+{% for syscall in syscalls  %}
+{% if syscall in supported_syscalls %}
+{{ arch_syscalls.append( syscall) }}
+{% endif %}
+{% endfor %}
+-a always,exit -F arch=b64 -S {{ arch_syscalls|join(',') }} -F auid=>{{ prelim_min_int_uid }} -F auid!=unset -k perm_mod
+{% set syscalls = ["chown","fchown","lchown","fchownat"] %}
+{% set arch_syscalls = [] %}
+{% for syscall in syscalls  %}
+{% if syscall in supported_syscalls %}
+{{ arch_syscalls.append( syscall) }}
+{% endif %}
+{% endfor %}
+-a always,exit -F arch=b64 -S {{ arch_syscalls|join(',') }} -F auid=>{{ prelim_min_int_uid }} -F auid!=unset -k perm_mod
+{% set syscalls = ["setxattr","lsetxattr","fsetxattr","removexattr","lremovexattr","fremovexattr"] %}
+{% set arch_syscalls = [] %}
+{% for syscall in syscalls  %}
+{% if syscall in supported_syscalls %}
+{{ arch_syscalls.append( syscall) }}
+{% endif %}
+{% endfor %}
+-a always,exit -F arch=b64 -S {{ arch_syscalls|join(',') }} -F auid=>{{ prelim_min_int_uid }} -F auid!=unset -k perm_mod
+{% set syscalls = ["chmod","fchmod","fchmodat"] %}
+{% set arch_syscalls = [] %}
+{% for syscall in syscalls  %}
+{% if syscall in supported_syscalls %}
+{{ arch_syscalls.append( syscall) }}
+{% endif %}
+{% endfor %}
+-a always,exit -F arch=b32 -S {{ arch_syscalls|join(',') }} -F auid=>{{ prelim_min_int_uid }} -F auid!=unset -k perm_mod
+{% set syscalls = ["chown","fchown","lchown","fchownat"] %}
+{% set arch_syscalls = [] %}
+{% for syscall in syscalls  %}
+{% if syscall in supported_syscalls %}
+{{ arch_syscalls.append( syscall) }}
+{% endif %}
+{% endfor %}
+-a always,exit -F arch=b32 -S {{ arch_syscalls|join(',') }} -F auid=>{{ prelim_min_int_uid }} -F auid!=unset -k perm_mod
+{% set syscalls = ["setxattr","lsetxattr","fsetxattr","removexattr","lremovexattr","fremovexattr"] %}
+{% set arch_syscalls = [] %}
+{% for syscall in syscalls  %}
+{% if syscall in supported_syscalls %}
+{{ arch_syscalls.append( syscall) }}
+{% endif %}
+{% endfor %}
+-a always,exit -F arch=b32 -S {{ arch_syscalls|join(',') }} -F auid=>{{ prelim_min_int_uid }} -F auid!=unset -k perm_mod
 {% endif %}
 {% if rhel9cis_rule_6_3_3_10 %}
--a always,exit -F arch=b32 -S mount -F auid>={{ prelim_min_int_uid }} -F auid!=unset -k mounts
--a always,exit -F arch=b64 -S mount -F auid>={{ prelim_min_int_uid }} -F auid!=unset -k mounts
+{% set syscalls = ["mount"] %}
+{% set arch_syscalls = [] %}
+{% for syscall in syscalls  %}
+{% if syscall in supported_syscalls %}
+{{ arch_syscalls.append( syscall) }}
+{% endif %}
+{% endfor %}
+-a always,exit -F arch=b64 -S {{ arch_syscalls|join(',') }} -F auid=>{{ prelim_min_int_uid }} -F auid!=unset -k mounts
+-a always,exit -F arch=b32 -S {{ arch_syscalls|join(',') }} -F auid=>{{ prelim_min_int_uid }} -F auid!=unset -k mounts
+{% endif %}
 {% endif %}
 {% if rhel9cis_rule_6_3_3_11 %}
 -w /var/run/utmp -p wa -k session
@@ -72,8 +149,15 @@
 -w /var/run/faillock -p wa -k logins
 {% endif %}
 {% if rhel9cis_rule_6_3_3_13 %}
--a always,exit -F arch=b64 -S rename,unlink,unlinkat,renameat -F auid>={{ prelim_min_int_uid }} -F auid!=unset -F key=delete
--a always,exit -F arch=b32 -S rename,unlink,unlinkat,renameat -F auid>={{ prelim_min_int_uid }} -F auid!=unset -F key=delete
+{% set syscalls = ["unlink","unlinkat","rename","renameat"] %}
+{% set arch_syscalls = [] %}
+{% for syscall in syscalls  %}
+{% if syscall in supported_syscalls %}
+{{ arch_syscalls.append( syscall) }}
+{% endif %}
+{% endfor %}
+-a always,exit -F arch=b64 -S {{ arch_syscalls|join(',') }} -F auid=>{{ prelim_min_int_uid }} -F auid!=unset -k delete
+-a always,exit -F arch=b32 -S {{ arch_syscalls|join(',') }} -F auid=>{{ prelim_min_int_uid }} -F auid!=unset -k delete
 {% endif %}
 {% if rhel9cis_rule_6_3_3_14 %}
 -w /etc/selinux -p wa -k MAC-policy
@@ -92,8 +176,15 @@
 -a always,exit -F path=/usr/sbin/usermod -F perm=x -F auid>={{ prelim_min_int_uid }} -F auid!=unset -k usermod
 {% endif %}
 {% if rhel9cis_rule_6_3_3_19 %}
--a always,exit -F arch=b64 -S init_module,finit_module,delete_module,create_module,query_module -F auid>={{ prelim_min_int_uid }} -F auid!=unset -k kernel_modules
--a always,exit -F path=/usr/bin/kmod -F perm=x -F auid>={{ prelim_min_int_uid }} -F auid!=unset -k kernel_modules
+-a always,exit -F path=/usr/bin/kmod -F perm=x -F auid=>{{ prelim_min_int_uid }} -F auid!=-1 -k kernel_modules
+{% set syscalls = ["init_module","finit_module","delete_module","create_module","query_module"] %}
+{% set arch_syscalls = [] %}
+{% for syscall in syscalls  %}
+{% if syscall in supported_syscalls %}
+{{ arch_syscalls.append( syscall) }}
+{% endif %}
+{% endfor %}
+-a always,exit -F arch=b64 -S {{ arch_syscalls|join(',') }} -F auid=>{{ prelim_min_int_uid }} -F auid!=-1 -k kernel_modules
 {% endif %}
 {% if rhel9cis_rule_6_3_3_20 %}
 -e 2