Restrict nova migration ssh tunnel

This change enhances the security of the migration ssh tunnel:
- The ssh authorized_keys file is only writeable by root.
- Creates a new user for migration instead of using root/nova.
- Disables SSH forwarding for this user.
- Optionally restricts the networks that this user can connect from.
- Uses an ssh wrapper command to whitelist the commands that this user can run
  over ssh.

Requires the openstack-nova-migration package from
https://review.rdoproject.org/r/6327

bp tripleo-cold-migration

Change-Id: Idb56acd1e1ecb5a5fd4d942969be428cc9cbe293
(cherry picked from commit f8ca94a5b7c7658631f5b0a9b010251ebbcff65e)

1 files changed, 89 insertions, 45 deletions

diff --git a/manifests/profile/base/nova.pp b/manifests/profile/base/nova.pp
index b4330a9..6c097f8 100644
--- a/manifests/profile/base/nova.pp
+++ b/manifests/profile/base/nova.pp
@@ -67,24 +67,30 @@
 #   Expects a hash with keys 'private_key' and 'public_key'.
 #   Defaults to {}
 #
+# [*migration_ssh_localaddrs*]
+#   (Optional) Restrict ssh migration to clients connecting via this list of
+#   IPs.
+#   Defaults to [] (no restriction)
+#
 # [*libvirt_tls*]
 #   (Optional) Whether or not libvird TLS service is enabled.
 #   Defaults to false
 
 class tripleo::profile::base::nova (
-  $bootstrap_node       = hiera('bootstrap_nodeid', undef),
-  $libvirt_enabled      = false,
-  $manage_migration     = false,
-  $messaging_driver     = hiera('messaging_service_name', 'rabbit'),
-  $messaging_hosts      = any2array(hiera('rabbitmq_node_names', undef)),
-  $messaging_password   = hiera('nova::rabbit_password'),
-  $messaging_port       = hiera('nova::rabbit_port', '5672'),
-  $messaging_username   = hiera('nova::rabbit_userid', 'guest'),
-  $messaging_use_ssl    = hiera('nova::rabbit_use_ssl', '0'),
-  $nova_compute_enabled = false,
-  $step                 = hiera('step'),
-  $migration_ssh_key       = {},
-  $libvirt_tls             = false
+  $bootstrap_node           = hiera('bootstrap_nodeid', undef),
+  $libvirt_enabled          = false,
+  $manage_migration         = false,
+  $messaging_driver         = hiera('messaging_service_name', 'rabbit'),
+  $messaging_hosts          = any2array(hiera('rabbitmq_node_names', undef)),
+  $messaging_password       = hiera('nova::rabbit_password'),
+  $messaging_port           = hiera('nova::rabbit_port', '5672'),
+  $messaging_username       = hiera('nova::rabbit_userid', 'guest'),
+  $messaging_use_ssl        = hiera('nova::rabbit_use_ssl', '0'),
+  $nova_compute_enabled     = false,
+  $step                     = hiera('step'),
+  $migration_ssh_key        = {},
+  $migration_ssh_localaddrs = [],
+  $libvirt_tls              = false
 ) {
   if $::hostname == downcase($bootstrap_node) {
     $sync_db = true
@@ -106,10 +112,22 @@ class tripleo::profile::base::nova (
       backend          => 'oslo_cache.memcache_pool',
       memcache_servers => $memcache_servers,
     }
-    include ::nova::placement
 
-    if $step >= 4 and $manage_migration {
+    class { '::nova' :
+      default_transport_url => os_transport_url({
+        'transport' => $messaging_driver,
+        'hosts'     => $messaging_hosts,
+        'port'      => sprintf('%s', $messaging_port),
+        'username'  => $messaging_username,
+        'password'  => $messaging_password,
+        'ssl'       => $messaging_use_ssl_real,
+      })
+    }
+    include ::nova::placement
+  }
 
+  if $step >= 4 {
+    if $manage_migration {
       # Libvirt setup (live-migration)
       if $libvirt_tls {
         class { '::nova::migration::libvirt':
@@ -123,49 +141,75 @@ class tripleo::profile::base::nova (
           transport          => 'ssh',
           configure_libvirt  => $libvirt_enabled,
           configure_nova     => $nova_compute_enabled,
-          client_user        => 'nova',
-          client_extraparams => {'keyfile' => '/var/lib/nova/.ssh/id_rsa'}
+          client_user        => 'nova_migration',
+          client_extraparams => {'keyfile' => '/etc/nova/migration/identity'}
         }
       }
 
-      if $migration_ssh_key != {} {
+      $services_enabled = hiera('service_names', [])
+      if !empty($migration_ssh_key) and 'sshd' in $services_enabled {
         # Nova SSH tunnel setup (cold-migration)
 
-        #TODO: Remove me when https://review.rdoproject.org/r/#/c/4008 lands
-        user { 'nova':
-          ensure => present,
-          shell  => '/bin/bash',
+        # Server side
+        if !empty($migration_ssh_localaddrs) {
+          $allow_type = sprintf('LocalAddress %s User', join($migration_ssh_localaddrs,','))
+          $deny_type = 'LocalAddress'
+          $deny_name = sprintf('!%s', join($migration_ssh_localaddrs,',!'))
+
+          ssh::server::match_block { 'nova_migration deny':
+            name    => $deny_name,
+            type    => $deny_type,
+            order   => 2,
+            options => {
+              'DenyUsers' => 'nova_migration'
+            },
+            notify  => Service['sshd']
+          }
+        }
+        else {
+          $allow_type = 'User'
+        }
+        $allow_name = 'nova_migration'
+
+        ssh::server::match_block { 'nova_migration allow':
+          name    => $allow_name,
+          type    => $allow_type,
+          order   => 1,
+          options => {
+            'ForceCommand'           => '/bin/nova-migration-wrapper',
+            'PasswordAuthentication' => 'no',
+            'AllowTcpForwarding'     => 'no',
+            'X11Forwarding'          => 'no',
+            'AuthorizedKeysFile'     => '/etc/nova/migration/authorized_keys'
+          },
+          notify  => Service['sshd']
         }
 
-        $private_key_parts = split($migration_ssh_key['public_key'], ' ')
-        $nova_public_key = {
-          'type' => $private_key_parts[0],
-          key    => $private_key_parts[1]
+        file { '/etc/nova/migration/authorized_keys':
+          content => $migration_ssh_key['public_key'],
+          mode    => '0640',
+          owner   => 'root',
+          group   => 'nova_migration',
+          require => Package['openstack-nova-migration'],
         }
-        $nova_private_key = {
-          'type' => $private_key_parts[0],
-          key    => $migration_ssh_key['private_key']
+
+        # Client side
+        file { '/etc/nova/migration/identity':
+          content => $migration_ssh_key['private_key'],
+          mode    => '0600',
+          owner   => 'nova',
+          group   => 'nova',
+          require => Package['openstack-nova-migration'],
         }
+        $migration_pkg_ensure = installed
       } else {
-        $nova_public_key = undef
-        $nova_private_key = undef
+        $migration_pkg_ensure = absent
       }
     } else {
-      $nova_public_key = undef
-      $nova_private_key = undef
+      $migration_pkg_ensure = absent
     }
-
-    class { '::nova' :
-      default_transport_url => os_transport_url({
-        'transport' => $messaging_driver,
-        'hosts'     => $messaging_hosts,
-        'port'      => sprintf('%s', $messaging_port),
-        'username'  => $messaging_username,
-        'password'  => $messaging_password,
-        'ssl'       => $messaging_use_ssl_real,
-      }),
-      nova_public_key       => $nova_public_key,
-      nova_private_key      => $nova_private_key,
+    package {'openstack-nova-migration':
+      ensure => $migration_pkg_ensure
     }
   }
 }