SELinux troubleshooting guide

_toc.yml

@@ -85,6 +85,7 @@ chapters:
           - file: admin-guide/troubleshooting/deployment
           - file: admin-guide/troubleshooting/login
           - file: admin-guide/troubleshooting/package_management
+          - file: admin-guide/troubleshooting/selinux
           - file: admin-guide/troubleshooting/boot
           - file: admin-guide/troubleshooting/kerberos
 

admin-guide/troubleshooting/selinux.md

@@ -0,0 +1,89 @@
+# SELinux
+
+
+## Basic Checks and Actions
+
+Check mode/status SELinux:
+```bash
+getenforce
+```
+
+Change mode/status SELinux from enforce to permissive:
+```bash
+setenforce 0
+```
+
+Show SELinux context of a file:
+```bash
+ls -Z <file>
+```
+
+Show SELinux context attached to process
+```bash
+ps -Z
+```
+
+Show SELinux booleans
+```bash
+getsebool -a
+```
+
+Set SELinux boolean
+```bash
+setsebool -P httpd_can_connect_ldap on
+setsebool -P httpd_can_check_spam off
+```
+`-P` makes it permanent and it will survive reboots.
+
+List defined SELinux contexts:
+```bash
+semanage fcontext --list
+```
+
+Add SELinux context for directories/files:
+```bash
+semanage fcontext --add -t httpd_log_t "/var/www(/.*)?/log(/.*)?"
+```
+
+Restore SELinux context of a directory/file
+```bash
+restorecon -Rv /var/www/html/var
+```
+
+## in Depth Log Analysis and Module Creation
+
+Ensure that `setroubleshoot-server` is installed for better readable log entries in `/var/log/audit/audit.log` and the journal.
+
+To be sure you see everything, enable full logging with
+```bash
+semodule -DB
+```
+
+Check the new log entries since the start of your test
+```bash
+ausearch -ts 14:29
+```
+
+Create a new SELinux policy file for the events logged since the start of your test
+
+```bash
+ausearch -ts 14:28 --raw | audit2allow -M my-application
+```
+
+This will create a `my-application.te` policy file with the source code (e.g. to be modified and distributed with Ansible or Puppet) and the copiled `my-application.pp` policy file.
+
+To install the new SELinux policy file run
+```bash
+semodule --install my-application.pp
+```
+
+To compile the binary SELinux policy file yourself run
+```bash
+cd /tmp; checkmodule --mls -m --output my-application.mod $PATH_TO/my-application.te; semodule_package --outfile my-application.pp --module my-application.mod
+```
+
+
+References:
+- [SELinux Guide](https://docs.linuxfabrik.ch/base/security/selinux.html) (German)
+- How to read SELinux logs: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/using_selinux/troubleshooting-problems-related-to-selinux_using-selinux
+- https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/using_selinux/troubleshooting-problems-related-to-selinux_using-selinux