sshd_selinux - Man Page

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

The sshd processes execute with the sshd_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 sshd_t

The sshd_t SELinux type can be entered via the sshd_exec_t file type.

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

/usr/bin/sshd, /usr/bin/gsisshd

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

The following process types are defined for sshd:

sshd_t, sshd_sandbox_t, sshd_net_t, ssh_keygen_t, sshd_keygen_t, ssh_t, ssh_keysign_t

Note: semanage permissive -a sshd_t can be used to make the process type sshd_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.  sshd policy is extremely flexible and has several booleans that allow you to manipulate the policy and run sshd with the tightest access possible.

If you want to allow ssh logins as sysadm_r:sysadm_t, you must turn on the ssh_sysadm_login boolean. Disabled by default.

setsebool -P ssh_sysadm_login 1

If you want to allow sshd to use tcp wrappers, you must turn on the ssh_use_tcpd boolean. Disabled by default.

setsebool -P ssh_use_tcpd 1

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 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 enable polyinstantiated directory support, you must turn on the polyinstantiation_enabled boolean. Disabled by default.

setsebool -P polyinstantiation_enabled 1

If you want to allow a user to login as an unconfined domain, you must turn on the unconfined_login boolean. Enabled by default.

setsebool -P unconfined_login 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 sshd policy is very flexible allowing users to setup their sshd processes in as secure a method as possible.

The following port types are defined for sshd:

    ssh_port_t

Default Defined Ports: tcp 22

The SELinux process type sshd_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.

auth_cache_t

/var/cache/coolkey(/.*)?

auth_home_t

/root/.yubico(/.*)?
/root/.config/Yubico(/.*)?
/root/.google_authenticator
/root/.google_authenticator~
/home/[^/]+/.yubico(/.*)?
/home/[^/]+/.config/Yubico(/.*)?
/home/[^/]+/.google_authenticator
/home/[^/]+/.google_authenticator~

cifs_t

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

condor_var_lib_t

/var/lib/condor(/.*)?
/var/lib/condor/spool(/.*)?
/var/lib/condor/execute(/.*)?

ecryptfs_t

/home/[^/]+/.Private(/.*)?
/home/[^/]+/.ecryptfs(/.*)?

faillog_t

/var/log/btmp.*
/run/faillock(/.*)?
/var/log/faillog.*
/var/log/tallylog.*

fusefs_t

/run/user/[0-9]+/gvfs

gitosis_var_lib_t

/srv/lib/gitosis(/.*)?
/var/lib/gitosis(/.*)?
/var/lib/gitolite(3)?(/.*)?

initrc_var_run_t

/run/utmp
/run/random-seed
/run/runlevel.dir
/run/setmixer_flag

kadmind_tmp_t

/var/tmp/kadmin_0
/var/tmp/kiprop_0

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

lastlog_t

/var/log/lastlog.*

nfs_t

openshift_tmp_t

/var/lib/openshift/.*/.tmp(/.*)?
/var/lib/openshift/.*/.sandbox(/.*)?
/var/lib/stickshift/.*/.tmp(/.*)?
/var/lib/stickshift/.*/.sandbox(/.*)?

pam_var_run_t

/var/(db|adm)/sudo(/.*)?
/run/sudo(/.*)?
/run/pam_ssh(/.*)?
/run/sepermit(/.*)?
/var/lib/sudo(/.*)?
/run/pam_mount(/.*)?
/run/pam_timestamp(/.*)?

root_t

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

security_t

/selinux

sshd_var_run_t

/run/sshd.pid
/run/sshd.init.pid

systemd_passwd_var_run_t

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

user_tmp_t

/run/user/[^/]+
/dev/shm/mono.*
/tmp/.ICE-unix(/.*)?
/tmp/.X11-unix(/.*)?
/dev/shm/pulse-shm.*
/run/user
/tmp/.X0-lock
/tmp/hsperfdata_root
/var/tmp/hsperfdata_root
/home/[^/]+/tmp
/home/[^/]+/.tmp
/run/user/[0-9]+
/tmp/gconfd-[^/]+

user_tmp_type

all user tmp files

var_auth_t

/var/ace(/.*)?
/var/rsa(/.*)?
/var/lib/abl(/.*)?
/var/lib/rsa(/.*)?
/var/lib/pam_ssh(/.*)?
/var/lib/pam_shield(/.*)?
/var/opt/quest/vas/vasd(/.*)?
/var/lib/google-authenticator(/.*)?

wtmp_t

/var/log/wtmp.*

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

STANDARD FILE CONTEXT

SELinux defines the file context types for the sshd, 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 sshd_keygen_exec_t '/srv/sshd/content(/.*)?'
restorecon -R -v /srv/mysshd_content

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

The following file types are defined for sshd:

sshd_exec_t

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

Paths:

/usr/bin/sshd, /usr/bin/gsisshd

sshd_initrc_exec_t

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

sshd_key_t

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

Paths:

/etc/ssh/ssh_host.*_key, /etc/ssh/ssh_host.*_key.pub, /etc/ssh/primes

sshd_keygen_exec_t

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

Paths:

/usr/bin/sshd-keygen, /usr/libexec/openssh/sshd-keygen

sshd_keygen_unit_file_t

- Set files with the sshd_keygen_unit_file_t type, if you want to treat the files as sshd keygen unit content.

sshd_keytab_t

- Set files with the sshd_keytab_t type, if you want to treat the files as kerberos keytab files.

sshd_tmpfs_t

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

sshd_unit_file_t

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

sshd_var_run_t

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

Paths:

/run/sshd.pid, /run/sshd.init.pid

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), sshd(8), semanage(8), restorecon(8), chcon(1), sepolicy(8), setsebool(8), ssh_keygen_selinux(8), ssh_keysign_selinux(8), sshd_keygen_selinux(8), sshd_net_selinux(8), sshd_sandbox_selinux(8)