chronyd_selinux - Man Page

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

The chronyd processes execute with the chronyd_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 chronyd_t

The chronyd_t SELinux type can be entered via the chronyd_exec_t file type.

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

/usr/bin/chronyd, /usr/libexec/chrony-helper

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

The following process types are defined for chronyd:

chronyd_t, chronyd_restricted_t

Note: semanage permissive -a chronyd_t can be used to make the process type chronyd_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.  chronyd policy is extremely flexible and has several booleans that allow you to manipulate the policy and run chronyd 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

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

The following port types are defined for chronyd:

    chronyd_port_t

Default Defined Ports: udp 323

The SELinux process type chronyd_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.

chronyd_tmp_t

chronyd_tmpfs_t

chronyd_var_lib_t

/var/lib/chrony(/.*)?

chronyd_var_run_t

/run/chrony(/.*)?
/run/chronyd(/.*)?
/run/chrony-dhcp(/.*)?
/run/chrony-helper(/.*)?
/run/chronyd.pid
/run/chronyd.sock

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

root_t

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

systemd_passwd_var_run_t

/run/systemd/ask-password(/.*)?
/run/systemd/ask-password-block(/.*)?

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

STANDARD FILE CONTEXT

SELinux defines the file context types for the chronyd, 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 chronyd_exec_t '/srv/chronyd/content(/.*)?'
restorecon -R -v /srv/mychronyd_content

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

The following file types are defined for chronyd:

chronyd_exec_t

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

Paths:

/usr/bin/chronyd, /usr/libexec/chrony-helper

chronyd_initrc_exec_t

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

chronyd_keys_t

- Set files with the chronyd_keys_t type, if you want to treat the files as chronyd keys data.

chronyd_tmp_t

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

chronyd_tmpfs_t

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

chronyd_unit_file_t

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

chronyd_var_lib_t

- Set files with the chronyd_var_lib_t type, if you want to store the chronyd files under the /var/lib directory.

chronyd_var_log_t

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

chronyd_var_run_t

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

Paths:

/run/chrony(/.*)?, /run/chronyd(/.*)?, /run/chrony-dhcp(/.*)?, /run/chrony-helper(/.*)?, /run/chronyd.pid, /run/chronyd.sock

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), chronyd(8), semanage(8), restorecon(8), chcon(1), sepolicy(8), setsebool(8), chronyd_restricted_selinux(8)