Security-Enhanced Linux secures the useradd processes via flexible mandatory access control.
The useradd processes execute with the useradd_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 useradd_t
The useradd_t SELinux type can be entered via the user_home_t, useradd_exec_t file types.
The default entrypoint paths for the useradd_t domain are the following:
/home/[^/]+/.+, /usr/sbin/useradd, /usr/sbin/userdel, /usr/sbin/usermod, /usr/sbin/newusers
You can see the context of a process using the -Z option to psP Policy governs the access confined processes have to files. SELinux useradd policy is very flexible allowing users to setup their useradd processes in as secure a method as possible.
The following process types are defined for useradd:
useradd_t
Note: semanage permissive -a useradd_t can be used to make the process type useradd_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
If you want to allow samba to act as the domain controller, add users, groups and change passwords, you must turn on the samba_domain_controller boolean. Disabled by default.
setsebool -P samba_domain_controller 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
The SELinux process type useradd_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.
cifs_t
default_context_t
/etc/selinux/([^/]*/)?contexts(/.*)?
/root/.default_contexts
etc_runtime_t
/[^/]+
/etc/mtab.*
/etc/blkid(/.*)?
/etc/nologin.*
/etc/.fstab.hal..+
/halt
/fastboot
/poweroff
/.autofsck
/etc/cmtab
/forcefsck
/.suspended
/fsckoptions
/.autorelabel
/etc/.updated
/var/.updated
/etc/killpower
/etc/nohotplug
/etc/securetty
/etc/ioctl.save
/etc/fstab.REVOKE
/etc/network/ifstate
/etc/sysconfig/hwconf
/etc/ptal/ptal-printd-like
/etc/sysconfig/iptables.save
/etc/xorg.conf.d/00-system-setup-keyboard.conf
/etc/X11/xorg.conf.d/00-system-setup-keyboard.conf
etc_t
/etc/.*
/usr/etc(/.*)?
/var/ftp/etc(/.*)?
/var/lib/openshift/.limits.d(/.*)?
/var/lib/openshift/.openshift-proxy.d(/.*)?
/var/lib/openshift/.stickshift-proxy.d(/.*)?
/var/lib/stickshift/.limits.d(/.*)?
/var/lib/stickshift/.stickshift-proxy.d(/.*)?
/etc/ipsec.d/examples(/.*)?
/var/named/chroot/etc(/.*)?
/var/spool/postfix/etc(/.*)?
/etc
/run/cockpit/motd
/etc/cups/client.conf
faillog_t
/var/log/btmp.*
/var/log/faillog.*
/var/log/tallylog.*
/var/run/faillock(/.*)?
file_context_t
/etc/selinux/([^/]*/)?contexts/files(/.*)?
httpd_user_content_type
initrc_var_run_t
/var/run/utmp
/var/run/random-seed
/var/run/runlevel.dir
/var/run/setmixer_flag
krb5kdc_var_lib_t
/var/lib/kdcproxy(/.*)?
lastlog_t
/var/log/lastlog.*
mail_spool_t
/var/mail(/.*)?
/var/spool/imap(/.*)?
/var/spool/mail(/.*)?
/var/spool/smtpd(/.*)?
nfs_t
openshift_file_type
passwd_file_t
/etc/group[-+]?
/etc/passwd[-+]?
/etc/passwd.adjunct.*
/etc/ptmptmp
/etc/.pwd.lock
/etc/group.lock
/etc/passwd.OLD
/etc/passwd.lock
security_t
/selinux
selinux_config_t
/etc/selinux(/.*)?
/etc/selinux/([^/]*/)?seusers
/etc/selinux/([^/]*/)?users(/.*)?
/etc/selinux/([^/]*/)?setrans.conf
/var/lib/sepolgen(/.*)?
selinux_login_config_t
/etc/selinux/([^/]*/)?logins(/.*)?
semanage_read_lock_t
/etc/selinux/([^/]*/)?modules/semanage.read.LOCK
/var/lib/selinux/[^/]+/semanage.read.LOCK
semanage_store_t
/etc/selinux/([^/]*/)?policy(/.*)?
/etc/selinux/(minimum|mls|targeted)/active(/.*)?
/etc/selinux/([^/]*/)?modules/(active|tmp|previous)(/.*)?
/var/lib/selinux(/.*)?
/etc/share/selinux/mls(/.*)?
/etc/share/selinux/targeted(/.*)?
semanage_tmp_t
semanage_trans_lock_t
/etc/selinux/([^/]*/)?modules/semanage.trans.LOCK
/var/lib/selinux/[^/]+/semanage.trans.LOCK
shadow_t
/etc/shadow.*
/etc/gshadow.*
/etc/nshadow.*
/var/db/shadow.*
/etc/security/opasswd
/etc/security/opasswd.old
smsd_var_lib_t
/var/lib/smstools(/.*)?
sssd_public_t
/var/lib/sss/mc(/.*)?
/var/lib/sss/pubconf(/.*)?
sssd_var_lib_t
/var/lib/sss(/.*)?
stapserver_var_lib_t
/var/lib/stap-server(/.*)?
user_home_type
all user home files
useradd_var_run_t
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 useradd policy is very flexible allowing users to setup their useradd processes in as secure a method as possible.
STANDARD FILE CONTEXT
SELinux defines the file context types for the useradd, 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 useradd_var_run_t '/srv/myuseradd_content(/.*)?'
restorecon -R -v /srv/myuseradd_content
Note: SELinux often uses regular expressions to specify labels that match multiple files.
The following file types are defined for useradd:
useradd_exec_t
- Set files with the useradd_exec_t type, if you want to transition an executable to the useradd_t domain.
useradd_var_run_t
- Set files with the useradd_var_run_t type, if you want to store the useradd 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.