ntpd_selinux - Man Page

Security-Enhanced Linux secures the ntpd processes via flexible mandatory access control.

The ntpd processes execute with the ntpd_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 ntpd_t

The ntpd_t SELinux type can be entered via the ntpdate_exec_t, ntpd_exec_t file types.

The default entrypoint paths for the ntpd_t domain are the following:

/usr/bin/sntp, /usr/bin/ntpdate, /usr/libexec/ntpdate-wrapper, /etc/cron.(daily|weekly)/ntp-server, /etc/cron.(daily|weekly)/ntp-simple, /usr/bin/ntpd

SELinux defines process types (domains) for each process running on the system

You can see the context of a process using the -Z option to psbP

Policy governs the access confined processes have to files. SELinux ntpd policy is very flexible allowing users to setup their ntpd processes in as secure a method as possible.

The following process types are defined for ntpd:

ntpd_t

Note: semanage permissive -a ntpd_t can be used to make the process type ntpd_t permissive. SELinux does not deny access to permissive process types, but the AVC (SELinux denials) messages are still generated.

SELinux policy is customizable based on least access required.  ntpd policy is extremely flexible and has several booleans that allow you to manipulate the policy and run ntpd with the tightest access possible.

If you want to dontaudit all daemons scheduling requests (setsched, sys_nice), you must turn on the daemons_dontaudit_scheduling boolean. Enabled by default.

setsebool -P daemons_dontaudit_scheduling 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 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 support NFS home directories, you must turn on the use_nfs_home_dirs boolean. Disabled by default.

setsebool -P use_nfs_home_dirs 1

If you want to support SAMBA home directories, you must turn on the use_samba_home_dirs boolean. Disabled by default.

setsebool -P use_samba_home_dirs 1

SELinux defines port types to represent TCP and UDP ports.

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 ntpd policy is very flexible allowing users to setup their ntpd processes in as secure a method as possible.

The following port types are defined for ntpd:

    ntp_port_t

Default Defined Ports: udp 123

The SELinux process type ntpd_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

/run/crm(/.*)?
/run/cman_.*
/run/rsctmp(/.*)?
/run/aisexec.*
/run/heartbeat(/.*)?
/run/pcsd-ruby.socket
/run/corosync-qnetd(/.*)?
/run/corosync-qdevice(/.*)?
/run/pcsd.socket
/run/corosync.pid
/run/cpglockd.pid
/run/rgmanager.pid
/run/cluster/rgmanager.sk

gpsd_tmpfs_t

krb5_host_rcache_t

/var/tmp/krb5_0.rcache2
/var/cache/krb5rcache(/.*)?
/var/tmp/nfs_0
/var/tmp/DNS_25
/var/tmp/host_0
/var/tmp/imap_0
/var/tmp/HTTP_23
/var/tmp/HTTP_48
/var/tmp/ldap_55
/var/tmp/ldap_487
/var/tmp/ldapmap1_0

ntp_drift_t

/var/lib/ntp(/.*)?
/etc/ntp/data(/.*)?
/var/lib/sntp(/.*)?
/var/lib/sntp-kod(/.*)?

ntpd_log_t

/var/log/ntp.*
/var/log/xntpd.*
/var/log/ntpstats(/.*)?

ntpd_tmp_t

ntpd_tmpfs_t

ntpd_var_run_t

/run/ntpd.pid

root_t

/sysroot/ostree/deploy/.*-atomic/deploy(/.*)?
/
/initrd

tmpfs_t

/dev/shm
/run/shm
/usr/lib/udev/devices/shm

SELinux requires files to have an extended attribute to define the file type.

You can see the context of a file using the -Z option to lsbP

Policy governs the access confined processes have to these files. SELinux ntpd policy is very flexible allowing users to setup their ntpd processes in as secure a method as possible.

STANDARD FILE CONTEXT

SELinux defines the file context types for the ntpd, if you wanted to store files with these types in a different paths, you need to execute the semanage command to specify alternate labeling and then use restorecon to put the labels on disk.

semanage fcontext -a -t ntpd_exec_t '/srv/ntpd/content(/.*)?'
restorecon -R -v /srv/myntpd_content

Note: SELinux often uses regular expressions to specify labels that match multiple files.

The following file types are defined for ntpd:

ntpd_exec_t

- Set files with the ntpd_exec_t type, if you want to transition an executable to the ntpd_t domain.

Paths:

/etc/cron.(daily|weekly)/ntp-server, /etc/cron.(daily|weekly)/ntp-simple, /usr/bin/ntpd

ntpd_initrc_exec_t

- Set files with the ntpd_initrc_exec_t type, if you want to transition an executable to the ntpd_initrc_t domain.

ntpd_key_t

- Set files with the ntpd_key_t type, if you want to treat the files as ntpd key data.

Paths:

/etc/ntp/crypto(/.*)?, /etc/ntp/keys

ntpd_log_t

- Set files with the ntpd_log_t type, if you want to treat the data as ntpd log data, usually stored under the /var/log directory.

Paths:

/var/log/ntp.*, /var/log/xntpd.*, /var/log/ntpstats(/.*)?

ntpd_tmp_t

- Set files with the ntpd_tmp_t type, if you want to store ntpd temporary files in the /tmp directories.

ntpd_tmpfs_t

- Set files with the ntpd_tmpfs_t type, if you want to store ntpd files on a tmpfs file system.

ntpd_unit_file_t

- Set files with the ntpd_unit_file_t type, if you want to treat the files as ntpd unit content.

ntpd_var_run_t

- Set files with the ntpd_var_run_t type, if you want to store the ntpd files under the /run or /var/run directory.

ntpdate_exec_t

- Set files with the ntpdate_exec_t type, if you want to transition an executable to the ntpdate_t domain.

Paths:

/usr/bin/sntp, /usr/bin/ntpdate, /usr/libexec/ntpdate-wrapper

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 fcontext can also be used to manipulate default file context mappings.

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.

This manual page was auto-generated using sepolicy manpage .

selinux(8), ntpd(8), semanage(8), restorecon(8), chcon(1), sepolicy(8), setsebool(8)