第4章 Configuring SELinux for applications and services with non-standard configurations

Procedure

1. Start the httpd service and check the status:

   # systemctl start httpd
   # systemctl status httpd
   …
   httpd[14523]: (13)Permission denied: AH00072: make_sock: could not bind to address [::]:3131
   …
   systemd[1]: Failed to start The Apache HTTP Server.
   …

2. The SELinux policy assumes that httpd runs on port 80:

   # semanage port -l | grep http
   http_cache_port_t              tcp      8080, 8118, 8123, 10001-10010
   http_cache_port_t              udp      3130
   http_port_t                    tcp      80, 81, 443, 488, 8008, 8009, 8443, 9000
   pegasus_http_port_t            tcp      5988
   pegasus_https_port_t           tcp      5989

3. Change the SELinux type of port 3131 to match port 80:

   # semanage port -a -t http_port_t -p tcp 3131

4. Start httpd again:

   # systemctl start httpd

5. However, the content remains inaccessible:

   # wget localhost:3131/index.html
   …
   HTTP request sent, awaiting response... 403 Forbidden
   …

   Find the reason with the sealert tool:

   # sealert -l "*"
   …
   SELinux is preventing httpd from getattr access on the file /var/test_www/html/index.html.
   …

6. Compare SELinux types for the standard and the new path using the matchpathcon tool:

   # matchpathcon /var/www/html /var/test_www/html
   /var/www/html       system_u:object_r:httpd_sys_content_t:s0
   /var/test_www/html  system_u:object_r:var_t:s0

7. Change the SELinux type of the new /var/test_www/html/ content directory to the type of the default /var/www/html directory:

   # semanage fcontext -a -e /var/www /var/test_www

8. Relabel the /var directory recursively:

   # restorecon -Rv /var/
   ...
   Relabeled /var/test_www/html from unconfined_u:object_r:var_t:s0 to unconfined_u:object_r:httpd_sys_content_t:s0
   Relabeled /var/test_www/html/index.html from unconfined_u:object_r:var_t:s0 to unconfined_u:object_r:httpd_sys_content_t:s0

Verification

1. Check that the httpd service is running:

   # systemctl status httpd
   …
   Active: active (running)
   …
   systemd[1]: Started The Apache HTTP Server.
   httpd[14888]: Server configured, listening on: port 3131
   ...

2. Verify that the content provided by the Apache HTTP server is accessible:

   # wget localhost:3131/index.html
   …
   HTTP request sent, awaiting response... 200 OK
   Length: 0 [text/html]
   Saving to: ‘index.html'
   …