Security-Enhanced Linux secures the dhcpd processes via flexible mandatory access control.
The dhcpd processes execute with the dhcpd_t SELinux type. You can check if you have these processes running by executing the ps command with the -Z qualifier.
For example:
ps -eZ | grep dhcpd_t
The dhcpd_t SELinux type can be entered via the dhcpd_exec_t file type.
The default entrypoint paths for the dhcpd_t domain are the following:
/usr/sbin/dhcpd(6)?, /usr/sbin/dhcrelay(6)?
You can see the context of a process using the -Z option to psP Policy governs the access confined processes have to files. SELinux dhcpd policy is very flexible allowing users to setup their dhcpd processes in as secure a method as possible.
The following process types are defined for dhcpd:
dhcpd_t
Note: semanage permissive -a dhcpd_t can be used to make the process type dhcpd_t permissive. SELinux does not deny access to permissive process types, but the AVC (SELinux denials) messages are still generated.
If you want to determine whether DHCP daemon can use LDAP backends, you must turn on the dhcpd_use_ldap boolean. Disabled by default.
setsebool -P dhcpd_use_ldap 1
If you want to allow users to resolve user passwd entries directly from ldap rather then using a sssd server, you must turn on the authlogin_nsswitch_use_ldap boolean. Disabled by default.
setsebool -P authlogin_nsswitch_use_ldap 1
If you want to allow all domains to execute in fips_mode, you must turn on the fips_mode boolean. Enabled by default.
setsebool -P fips_mode 1
If you want to allow confined applications to run with kerberos, you must turn on the kerberos_enabled boolean. Enabled by default.
setsebool -P kerberos_enabled 1
If you want to allow system to run with NIS, you must turn on the nis_enabled boolean. Disabled by default.
setsebool -P nis_enabled 1
If you want to allow confined applications to use nscd shared memory, you must turn on the nscd_use_shm boolean. Enabled by default.
setsebool -P nscd_use_shm 1
You can see the types associated with a port by using the following command:
semanage port -l
Policy governs the access confined processes have to these ports. SELinux dhcpd policy is very flexible allowing users to setup their dhcpd processes in as secure a method as possible.
The following port types are defined for dhcpd:
Default Defined Ports: tcp 547,548,647,847,7911 udp 67,547,548,647,847
The SELinux process type dhcpd_t can manage files labeled with the following file types. The paths listed are the default paths for these file types. Note the processes UID still need to have DAC permissions.
cluster_conf_t
/etc/cluster(/.*)?
cluster_var_lib_t
/var/lib/pcsd(/.*)?
/var/lib/cluster(/.*)?
/var/lib/openais(/.*)?
/var/lib/pengine(/.*)?
/var/lib/corosync(/.*)?
/usr/lib/heartbeat(/.*)?
/var/lib/heartbeat(/.*)?
/var/lib/pacemaker(/.*)?
cluster_var_run_t
/var/run/crm(/.*)?
/var/run/cman_.*
/var/run/rsctmp(/.*)?
/var/run/aisexec.*
/var/run/heartbeat(/.*)?
/var/run/corosync-qnetd(/.*)?
/var/run/corosync-qdevice(/.*)?
/var/run/corosync.pid
/var/run/cpglockd.pid
/var/run/rgmanager.pid
/var/run/cluster/rgmanager.sk
dhcpd_state_t
/var/lib/dhcp(3)?/dhcpd.leases.*
/var/lib/dhcpd(/.*)?
dhcpd_tmp_t
dhcpd_var_run_t
/var/run/dhcpd(6)?.pid
root_t
/sysroot/ostree/deploy/.*-atomic/deploy(/.*)?
/
/initrd
You can see the context of a file using the -Z option to lsP Policy governs the access confined processes have to these files. SELinux dhcpd policy is very flexible allowing users to setup their dhcpd processes in as secure a method as possible.
STANDARD FILE CONTEXT
SELinux defines the file context types for the dhcpd, if you wanted to store files with these types in a diffent paths, you need to execute the semanage command to sepecify alternate labeling and then use restorecon to put the labels on disk.
semanage fcontext -a -t dhcpd_var_run_t '/srv/mydhcpd_content(/.*)?'
restorecon -R -v /srv/mydhcpd_content
Note: SELinux often uses regular expressions to specify labels that match multiple files.
The following file types are defined for dhcpd:
dhcpd_exec_t
- Set files with the dhcpd_exec_t type, if you want to transition an executable to the dhcpd_t domain.
dhcpd_initrc_exec_t
- Set files with the dhcpd_initrc_exec_t type, if you want to transition an executable to the dhcpd_initrc_t domain.
dhcpd_state_t
- Set files with the dhcpd_state_t type, if you want to treat the files as dhcpd state data.
dhcpd_tmp_t
- Set files with the dhcpd_tmp_t type, if you want to store dhcpd temporary files in the /tmp directories.
dhcpd_unit_file_t
- Set files with the dhcpd_unit_file_t type, if you want to treat the files as dhcpd unit content.
dhcpd_var_run_t
- Set files with the dhcpd_var_run_t type, if you want to store the dhcpd files under the /run or /var/run directory.
Note: File context can be temporarily modified with the chcon command. If you want to permanently change the file context you need to use the semanage fcontext command. This will modify the SELinux labeling database. You will need to use restorecon to apply the labels.
semanage permissive can also be used to manipulate whether or not a process type is permissive.
semanage module can also be used to enable/disable/install/remove policy modules.
semanage port can also be used to manipulate the port definitions
semanage boolean can also be used to manipulate the booleans
system-config-selinux is a GUI tool available to customize SELinux policy settings.