Selinux

list selinux setting on directory.

# ls -Zld /var/ www/cgi-bin /usr/local/linuxcoe-sd/cgi-bin/
drwxr-xr-x  2 root:object_r:usr_t              root root 4096 Jun 12 12:55 /usr/local/linuxcoe-sd/cgi-bin/
drwxr-xr-x  2 system_u:object_r:httpd_sys_script_exec_t root root 4096 Feb 28  2005 /var/www/cgi-bin

Copy security contex from another directory.

# chcon --reference=/var/www/cgi-bin -R /usr/local/linuxcoe-sd/cgi-bin

Show selinux status.

# sestatus

Set selinux status.

# setenforce Enforcing
# setenforce Permissive

View Processes protected by SELinux

# ps -ZC httpd

How to read selinux informatino

• user

The role is used to indicate the user of the context. If a user logs in as root they will have a user value of root. If they log in as a regular user, like tom, they will have the value of user_u. Users who su to root will continue to have the value of user_u. Processes also have a value, system_u.

• role

This is used to define the role of the user. Files have a role of object_r and processes have a role of system_r. Users, like processes have the role of system_r.

• type

Types are used to create a type enforcement which determines which process types can have access to which file types.

• sensitivity

This is a security feature used by government agencies.

• category

This provides a way to block access to categories of people including root.

user: role: type: sensitivity: category

If you view the settings for the index.html file in /var/www/html you will see these attributes listed.

# ls -Z

-rw-r--r-- root root root:object_r:httpd_sys_content_t index.html

user: root:

role: object_r:

type: httpd_sys_content_t

sensitivity:

category

Get selinux bolean values.

# getsebool -a

Enable bolean value, permanently.

# setsebool -P httpd_unified=1

Change mode of directory and subdirectories.

# chcon -R -t httpd_sys_content_rw_t /var/www/html/www-halfface/photos/album-data

Set selinux permission on home drive.

# chcon -R -t user_home_dir_t /home/anita/ && chcon -R -t user_home_t /home/anita/mail/

Restore selinux permission.

# restorecon /dir

roles known to the system.

# seinfo -r

Get graphical application showing selinux problems.

# sudo sealert -b

which ports are application able to listen on.

# semanage port -l

make httpd able to listen on port 81

# semanage port -a -t http_port_t -p tcp 81

view selinux activities

# aureport -i --input-logs --start recent --avc

Have a closer look at what an entry means.

# ausearch --input-logs -i -a 30492

View latest selinux logfile entries.

# ausearch -m avc --start recent

Vies one selinux log entry.

# ausearch -m avc -a 9293

Default policy

targeted

Generate loadable module package.

# grep munin /var/log/audit/audit.log | audit2allow -M munin > /temp/munin.te

load module.

# semodule -i munin.pp

list available modules

# semodule -l