ssh_selinux(8) - Linux man page

Name

ssh_selinux - Security Enhanced Linux Policy for the ssh processes

Description

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

The ssh processes execute with the ssh_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 ssh_t

Entrypoints

The ssh_t SELinux type can be entered via the "ssh_exec_t" file type. The default entrypoint paths for the ssh_t domain are the following:"

/usr/bin/ssh

Process Types

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 ps

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

The following process types are defined for ssh:

ssh_keysign_t, ssh_keygen_t, ssh_t, sshd_t

Note: semanage permissive -a ssh_t

can be used to make the process type ssh_t permissive. Permissive process types are not denied access by SELinux. AVC messages will still be generated.

Booleans

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

If you want to allow host key based authentication, you must turn on the allow_ssh_keysign boolean.

setsebool -P allow_ssh_keysign 1

If you want to allow ssh with chroot env to read and write files in the user home directories, you must turn on the ssh_chroot_rw_homedirs boolean.

setsebool -P ssh_chroot_rw_homedirs 1

If you want to allow ssh with chroot env to manage all files, you must turn on the ssh_chroot_full_access boolean.

setsebool -P ssh_chroot_full_access 1

If you want to allow fenced domain to execute ssh, you must turn on the fenced_can_ssh boolean.

setsebool -P fenced_can_ssh 1

If you want to allow ssh with chroot env to apache content, you must turn on the ssh_chroot_manage_apache_content boolean.

setsebool -P ssh_chroot_manage_apache_content 1

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

setsebool -P ssh_sysadm_login 1

If you want to allow host key based authentication, you must turn on the allow_ssh_keysign boolean.

setsebool -P allow_ssh_keysign 1

If you want to allow ssh with chroot env to read and write files in the user home directories, you must turn on the ssh_chroot_rw_homedirs boolean.

setsebool -P ssh_chroot_rw_homedirs 1

If you want to allow ssh with chroot env to manage all files, you must turn on the ssh_chroot_full_access boolean.

setsebool -P ssh_chroot_full_access 1

If you want to allow fenced domain to execute ssh, you must turn on the fenced_can_ssh boolean.

setsebool -P fenced_can_ssh 1

If you want to allow ssh with chroot env to apache content, you must turn on the ssh_chroot_manage_apache_content boolean.

setsebool -P ssh_chroot_manage_apache_content 1

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

setsebool -P ssh_sysadm_login 1

File Contexts

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 ls

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

The following file types are defined for ssh:

ssh_agent_exec_t

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

ssh_agent_tmp_t

- Set files with the ssh_agent_tmp_t type, if you want to store ssh agent temporary files in the /tmp directories.

ssh_exec_t

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

ssh_home_t

- Set files with the ssh_home_t type, if you want to store ssh files in the users home directory.

ssh_keygen_exec_t

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

ssh_keysign_exec_t

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

ssh_tmpfs_t

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

sshd_exec_t

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

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.

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_var_run_t

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

Port Types

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

The following port types are defined for ssh:

ssh_port_t
Default Defined Ports:: tcp 22

Managed Files

The SELinux process type ssh_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.

initrc_tmp_t

mnt_t

/mnt(/[^/]*)

/mnt(/[^/]*)?

/rhev(/[^/]*)?

/media(/[^/]*)

/media(/[^/]*)?

/etc/rhgb(/.*)?

/media/.hal-.*

/net

/afs

/misc

/rhev

nfs_t
ssh_home_t

/root/.ssh(/.*)?

/var/lib/gitolite(3)?/.ssh(/.*)?

/var/lib/openshift/[^/]+/.ssh(/.*)?

/var/lib/amanda/.ssh(/.*)?

/var/lib/stickshift/[^/]+/.ssh(/.*)?

/root/.shosts

/home/[^/]*/.ssh(/.*)?

/home/[^/]*/.shosts

ssh_tmpfs_t
tmp_t

/tmp

/usr/tmp

/var/tmp

/var/tmp/vi.recover

user_fonts_cache_t

/home/[^/]*/.fonts/auto(/.*)?

/home/[^/]*/.fontconfig(/.*)?

/home/[^/]*/.fonts.cache-.*

user_tmp_t

/tmp/gconfd-.*

Commands

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.

Author

This manual page was auto-generated using sepolicy manpage by mgrepl.