#DESC SSH - SSH daemon

#

# Authors:  Anthony Colatrella (NSA) <amcolat@epoch.ncsc.mil>

#           Stephen Smalley <sds@epoch.ncsc.mil>

#           Russell Coker <russell@coker.com.au>

# X-Debian-Packages: ssh

#

# Allow ssh logins as sysadm_r:sysadm_t

bool ssh_sysadm_login false;

# allow host key based authentication

bool allow_ssh_keysign false;

ifdef(`inetd.te', `

# Allow ssh to run from inetd instead of as a daemon.

bool run_ssh_inetd false;

')

# sshd_exec_t is the type of the sshd executable.

# sshd_key_t is the type of the ssh private key files

type sshd_exec_t, file_type, exec_type, sysadmfile;

type sshd_key_t, file_type, sysadmfile;

define(`sshd_program_domain', `

# privowner is for changing the identity on the terminal device

# privfd is for passing the terminal file handle to the user process

# auth_chkpwd is for running unix_chkpwd and unix_verify.

type $1_t, domain, privuser, privrole, privlog, privowner, privfd, auth_chkpwd, nscd_client_domain, mlsfileread, mlsfilewrite, mlsfileupgrade, mlsfiledowngrade, mlsprocsetsl;

can_exec($1_t, sshd_exec_t)

r_dir_file($1_t, self)

role system_r types $1_t;

dontaudit $1_t shadow_t:file { getattr read };

uses_shlib($1_t)

allow $1_t self:unix_dgram_socket create_socket_perms;

allow $1_t self:unix_stream_socket create_stream_socket_perms;

allow $1_t self:fifo_file rw_file_perms;

allow $1_t self:process { fork sigchld signal setsched setrlimit };

dontaudit $1_t self:lnk_file read;

# do not allow statfs()

dontaudit $1_t fs_type:filesystem getattr;

allow $1_t bin_t:dir search;

allow $1_t bin_t:lnk_file read;

# for sshd subsystems, such as sftp-server.

allow $1_t bin_t:file getattr;

# Read /var.

allow $1_t var_t:dir { getattr search };

# Read /var/log.

allow $1_t var_log_t:dir search;

# Read /etc.

allow $1_t etc_t:dir search;

# ioctl is for pam_console

dontaudit $1_t etc_t:file ioctl;

allow $1_t etc_t:file { getattr read };

allow $1_t etc_t:lnk_file { getattr read };

allow $1_t etc_runtime_t:file { getattr read };

# Read and write /dev/tty and /dev/null.

allow $1_t devtty_t:chr_file rw_file_perms;

allow $1_t { null_device_t zero_device_t }:chr_file rw_file_perms;

# Read /dev/urandom

allow $1_t urandom_device_t:chr_file { getattr read };

can_network($1_t)

allow $1_t port_type:tcp_socket name_connect;

can_kerberos($1_t)

allow $1_t self:capability { kill sys_chroot sys_resource chown dac_override fowner fsetid setgid setuid sys_tty_config };

allow $1_t { home_root_t home_dir_type }:dir { search getattr };

if (use_nfs_home_dirs) {

allow $1_t autofs_t:dir { search getattr };

allow $1_t nfs_t:dir { search getattr };

allow $1_t nfs_t:file { getattr read };

}

if (use_samba_home_dirs) {

allow $1_t cifs_t:dir { search getattr };

allow $1_t cifs_t:file { getattr read };

}

# Set exec context.

can_setexec($1_t)

# Update utmp.

allow $1_t initrc_var_run_t:file rw_file_perms;

# Update wtmp.

allow $1_t wtmp_t:file rw_file_perms;

# Get security policy decisions.

can_getsecurity($1_t)

# Allow read access to login context

r_dir_file( $1_t, default_context_t)

# Access key files

allow $1_t sshd_key_t:file { getattr read };

# Update /var/log/lastlog.

allow $1_t lastlog_t:file rw_file_perms;

read_locale($1_t)

read_sysctl($1_t)

# Can create ptys

can_create_pty($1, `, server_pty')

allow $1_t $1_devpts_t:chr_file { setattr getattr relabelfrom };

dontaudit sshd_t userpty_type:chr_file relabelfrom;

allow $1_t faillog_t:file { append getattr };

allow $1_t sbin_t:file getattr;

# Allow checking users mail at login

allow $1_t { var_spool_t mail_spool_t }:dir search;

allow $1_t mail_spool_t:lnk_file read;

allow $1_t mail_spool_t:file getattr;

')dnl end sshd_program_domain

# macro for defining which domains a sshd can spawn

# $1_t is the domain of the sshd, $2 is the domain to be spawned, $3 is the

# type of the pty for the child

define(`sshd_spawn_domain', `

login_spawn_domain($1, $2)

ifdef(`xauth.te', `

domain_trans($1_t, xauth_exec_t, $2)

')

# Relabel and access ptys created by sshd

# ioctl is necessary for logout() processing for utmp entry and for w to

# display the tty.

# some versions of sshd on the new SE Linux require setattr

allow $1_t $3:chr_file { relabelto read write getattr ioctl setattr };

# inheriting stream sockets is needed for "ssh host command" as no pty

# is allocated

allow $2 $1_t:unix_stream_socket rw_stream_socket_perms;

')dnl end sshd_spawn_domain definition

#################################

#

# Rules for the sshd_t domain, et al.

#

# sshd_t is the domain for the sshd program.

# sshd_extern_t is the domain for ssh from outside our network

#

sshd_program_domain(sshd)

if (ssh_sysadm_login) {

allow sshd_t devpts_t:dir r_dir_perms;

sshd_spawn_domain(sshd, userdomain, { sysadm_devpts_t userpty_type })

} else {

sshd_spawn_domain(sshd, unpriv_userdomain, userpty_type)

}

# for X forwarding

allow sshd_t xserver_port_t:tcp_socket name_bind;

r_dir_file(sshd_t, selinux_config_t)

sshd_program_domain(sshd_extern)

sshd_spawn_domain(sshd_extern, user_mini_domain, mini_pty_type)

# for when the network connection breaks after running newrole -r sysadm_r

dontaudit sshd_t sysadm_devpts_t:chr_file setattr;

ifdef(`inetd.te', `

if (run_ssh_inetd) {

allow inetd_t ssh_port_t:tcp_socket name_bind;

domain_auto_trans(inetd_t, sshd_exec_t, sshd_t)

domain_trans(inetd_t, sshd_exec_t, sshd_extern_t)

allow { sshd_t sshd_extern_t } inetd_t:tcp_socket rw_socket_perms;

allow { sshd_t sshd_extern_t } var_run_t:dir { getattr search };

allow { sshd_t sshd_extern_t } self:process signal;

} else {

')

can_access_pty({ sshd_t sshd_extern_t }, initrc)

allow { sshd_t sshd_extern_t } self:capability net_bind_service;

allow { sshd_t sshd_extern_t } ssh_port_t:tcp_socket name_bind;

# for port forwarding

can_tcp_connect(userdomain, sshd_t)

domain_auto_trans(initrc_t, sshd_exec_t, sshd_t)

domain_trans(initrc_t, sshd_exec_t, sshd_extern_t)

dontaudit initrc_t sshd_key_t:file { getattr read };

# Inherit and use descriptors from init.

allow { sshd_t sshd_extern_t } init_t:fd use;

ifdef(`inetd.te', `

}

')

# Create /var/run/sshd.pid

var_run_domain(sshd)

var_run_domain(sshd_extern)

ifdef(`direct_sysadm_daemon', `

# Direct execution by sysadm_r.

domain_auto_trans(sysadm_t, sshd_exec_t, sshd_t)

role_transition sysadm_r sshd_exec_t system_r;

')

undefine(`sshd_program_domain')

# so a tunnel can point to another ssh tunnel...

can_tcp_connect(sshd_t, sshd_t)

tmp_domain(sshd, `', { dir file sock_file })

ifdef(`pam.te', `

can_exec(sshd_t, pam_exec_t)

')

# ssh_keygen_t is the type of the ssh-keygen program when run at install time

# and by sysadm_t

daemon_base_domain(ssh_keygen)

allow ssh_keygen_t etc_t:file { getattr read };

file_type_auto_trans(ssh_keygen_t, etc_t, sshd_key_t, file)

# Type for the ssh executable.

type ssh_exec_t, file_type, exec_type, sysadmfile;

type ssh_keysign_exec_t, file_type, exec_type, sysadmfile;

# Everything else is in the ssh_domain macro in

# macros/program/ssh_macros.te.

allow ssh_keygen_t self:unix_stream_socket create_stream_socket_perms;

allow ssh_keygen_t sysadm_tty_device_t:chr_file { read write };

allow ssh_keygen_t urandom_device_t:chr_file { getattr read };

ifdef(`use_mcs', `

range_transition initrc_t sshd_exec_t s0 - s0:c0.c255;

')