Security-Enhanced Linux secures the krb5kdc processes via flexible mandatory access control.
The krb5kdc processes execute with the krb5kdc_t SELinux type. You can check if you have these processes running by executing the ps command with the -Z qualifier.
ps -eZ | grep krb5kdc_t
The krb5kdc_t SELinux type can be entered via the krb5kdc_exec_t file type.
The default entrypoint paths for the krb5kdc_t domain are the following:
You can see the context of a process using the -Z option to psP Policy governs the access confined processes have to files. SELinux krb5kdc policy is very flexible allowing users to setup their krb5kdc processes in as secure a method as possible.
The following process types are defined for krb5kdc:
Note: semanage permissive -a krb5kdc_t can be used to make the process type krb5kdc_t permissive. SELinux does not deny access to permissive process types, but the AVC (SELinux denials) messages are still generated.
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
The SELinux process type krb5kdc_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.
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 krb5kdc policy is very flexible allowing users to setup their krb5kdc processes in as secure a method as possible.
krb5kdc policy stores data with multiple different file context types under the /var/kerberos/krb5kdc directory. If you would like to store the data in a different directory you can use the semanage command to create an equivalence mapping. If you wanted to store this data under the /srv dirctory you would execute the following command:
semanage fcontext -a -e /var/kerberos/krb5kdc /srv/krb5kdc
restorecon -R -v /srv/krb5kdc
STANDARD FILE CONTEXT
SELinux defines the file context types for the krb5kdc, 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 krb5kdc_var_run_t '/srv/mykrb5kdc_content(/.*)?'
restorecon -R -v /srv/mykrb5kdc_content
Note: SELinux often uses regular expressions to specify labels that match multiple files.
The following file types are defined for krb5kdc:
- Set files with the krb5kdc_conf_t type, if you want to treat the files as krb5kdc configuration data, usually stored under the /etc directory.
- Set files with the krb5kdc_exec_t type, if you want to transition an executable to the krb5kdc_t domain.
- Set files with the krb5kdc_lock_t type, if you want to treat the files as krb5kdc lock data, stored under the /var/lock directory
- Set files with the krb5kdc_log_t type, if you want to treat the data as krb5kdc log data, usually stored under the /var/log directory.
- Set files with the krb5kdc_principal_t type, if you want to treat the files as krb5kdc principal data.
- Set files with the krb5kdc_tmp_t type, if you want to store krb5kdc temporary files in the /tmp directories.
- Set files with the krb5kdc_var_lib_t type, if you want to store the krb5kdc files under the /var/lib directory.
- Set files with the krb5kdc_var_run_t type, if you want to store the krb5kdc 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 boolean can also be used to manipulate the booleans
system-config-selinux is a GUI tool available to customize SELinux policy settings.