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Add safety checks to nspawn connection plugin

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This patch adds some checks on the path that is accessed as a container,
making sure it looks like one. It implements the connection method and
add adaptations to the modern way of writing connections for Ansible.
It also rewords docs and vars to use the nspawn terminology instead of
chroot.
This commit is contained in:
Thomas Szymanski 2017-02-03 23:33:38 +01:00 • committed by Brian Coca
commit 60bb677154
1 changed files with 101 additions and 46 deletions
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147
lib/ansible/plugins/connection/nspawn.py
View file

@ -1,17 +1,33 @@
# This file is part of Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible. If not, see <http://www.gnu.org/licenses/>.
from __future__ import (absolute_import, division, print_function) from __future__ import (absolute_import, division, print_function)
__metaclass__ = type __metaclass__ = type
import distutils.spawn
import os import os
import pipes import os.path
import subprocess import subprocess
import traceback import traceback
import shlex import shlex
from ansible import constants as C from ansible import constants as C
from ansible.compat import six
from ansible.compat.six.moves import shlex_quote
from ansible.errors import AnsibleError from ansible.errors import AnsibleError
from ansible.plugins.connection import ConnectionBase from ansible.module_utils._text import to_bytes, to_text
from ansible.module_utils.basic import is_executable from ansible.plugins.connection import ConnectionBase, BUFSIZE
from ansible.utils.unicode import to_bytes
try: try:
from __main__ import display from __main__ import display
@ -19,8 +35,6 @@ except ImportError:
from ansible.utils.display import Display from ansible.utils.display import Display
display = Display() display = Display()
BUFSIZE = 65536
class Connection(ConnectionBase): class Connection(ConnectionBase):
''' Local nspawn based connections ''' ''' Local nspawn based connections '''
@ -31,31 +45,43 @@ class Connection(ConnectionBase):
def __init__(self, play_context, new_stdin, *args, **kwargs): def __init__(self, play_context, new_stdin, *args, **kwargs):
super(Connection, self).__init__(play_context, new_stdin, super(Connection, self).__init__(play_context, new_stdin,
*args, **kwargs) *args, **kwargs)
display.vvv("NSPAWN ARGS %s" % self._play_context.nspawn_args) display.vvv("NSPAWN ARGS %s" % self._play_context.nspawn_args)
self.chroot = self._play_context.remote_addr self.ostree = os.path.normpath(self._play_context.remote_addr)
if os.geteuid() != 0: if os.geteuid() != 0:
raise AnsibleError("nspawn connection requires running as root") raise AnsibleError("nspawn connection requires running as root")
# we're running as root on the local system so do some # we're running as root on the local system so do some
# trivial checks for ensuring 'host' is actually a chroot'able dir # trivial checks for ensuring 'host' may be an OS tree dir
if not os.path.isdir(self.chroot): if not os.path.isdir(self.ostree):
raise AnsibleError("%s is not a directory" % self.chroot) raise AnsibleError("%s is not a directory" % self.ostree)
chrootsh = os.path.join(self.chroot, 'bin/sh') # As systemd-nspawn will, we check the existence of os-release files
if not is_executable(chrootsh): # in the container tree to think it looks like an OS tree enough
raise AnsibleError("%s does not look like a chrootable dir (/bin/sh missing)" % self.chroot) # see man systemd-nspawn(1) and os-release(5)
if not (
os.path.isfile(os.path.join(self.ostree, "usr/lib/os-release"))
or os.path.isfile(os.path.join(self.ostree, "etc/os-release"))
):
raise AnsibleError("%s does not contain an os-release file"
% self.ostree)
self.nspawn_cmd = 'systemd-nspawn' self.nspawn_cmd = distutils.spawn.find_executable('systemd-nspawn')
if not self.nspawn_cmd:
raise AnsibleError("systemd-nspawn command not found in PATH")
def _connect(self): def _connect(self):
pass ''' Connect to the container. Nothing to do '''
super(Connection, self)._connect()
if not self._connected:
display.vvv(u"THIS IS A LOCAL NSPAWN CONTAINER", host=self.ostree)
self._connected = True
def _buffered_exec_command(self, cmd, stdin=subprocess.PIPE): def _buffered_exec_command(self, cmd, stdin=subprocess.PIPE):
''' run a command on the chroot. This is only needed for ''' run a command in the container. This is only needed for
implementing put_file() get_file() so that we don't have to implementing put_file() get_file() so that we don't have to
read the whole file into memory. read the whole file into memory.
@ -63,24 +89,35 @@ class Connection(ConnectionBase):
able to return the process's exit code immediately. able to return the process's exit code immediately.
''' '''
executable = ( executable = (
C.DEFAULT_EXECUTABLE.split()[0] C.DEFAULT_EXECUTABLE.split()[0]
if C.DEFAULT_EXECUTABLE if C.DEFAULT_EXECUTABLE
else '/bin/sh') else '/bin/sh')
nspawn_args = shlex.split(self._play_context.nspawn_args) nspawn_args = self._play_context.nspawn_args
local_cmd = [self.nspawn_cmd, '-D', self.chroot ] + nspawn_args + [ if six.PY2:
'--', executable, '-c', cmd] nspawn_args = shlex.split(
to_bytes(nspawn_args, errors='surrogate_or_strict')
)
else:
nspawn_args = shlex.split(
to_text(nspawn_args, errors='surrogate_or_strict')
)
display.vvv("EXEC %s" % (local_cmd), host=self.chroot) local_cmd = [self.nspawn_cmd, '-D', self.ostree] + nspawn_args + [
local_cmd = map(to_bytes, local_cmd) '--', executable, '-c', cmd]
display.vvv("EXEC %s" % (local_cmd), host=self.ostree)
local_cmd = [to_bytes(i, errors='surrogate_or_strict')
for i in local_cmd]
p = subprocess.Popen(local_cmd, shell=False, stdin=stdin, p = subprocess.Popen(local_cmd, shell=False, stdin=stdin,
stdout=subprocess.PIPE, stderr=subprocess.PIPE) stdout=subprocess.PIPE, stderr=subprocess.PIPE)
return p return p
def exec_command(self, cmd, in_data=None, sudoable=False): def exec_command(self, cmd, in_data=None, sudoable=False):
''' run a command on the chroot ''' ''' run a command in the container '''
super(Connection, self).exec_command(cmd, in_data=in_data, sudoable=sudoable) super(Connection, self).exec_command(cmd, in_data=in_data,
sudoable=sudoable)
p = self._buffered_exec_command(cmd) p = self._buffered_exec_command(cmd)
stdout, stderr = p.communicate(in_data) stdout, stderr = p.communicate(in_data)
@ -91,7 +128,8 @@ class Connection(ConnectionBase):
If a path is relative, then we need to choose where to put it. If a path is relative, then we need to choose where to put it.
ssh chooses $HOME but we aren't guaranteed that a home dir will ssh chooses $HOME but we aren't guaranteed that a home dir will
exist in any given chroot. So for now we're choosing "/" instead. exist in any given container. So for now we're choosing "/"
instead.
This also happens to be the former default. This also happens to be the former default.
Can revisit using $HOME instead if it's a problem Can revisit using $HOME instead if it's a problem
@ -101,39 +139,54 @@ class Connection(ConnectionBase):
return os.path.normpath(remote_path) return os.path.normpath(remote_path)
def put_file(self, in_path, out_path): def put_file(self, in_path, out_path):
''' transfer a file from local to chroot ''' ''' transfer a file from local to the container '''
super(Connection, self).put_file(in_path, out_path) super(Connection, self).put_file(in_path, out_path)
display.vvv("PUT %s TO %s" % (in_path, out_path), host=self.chroot) display.vvv("PUT %s TO %s" % (in_path, out_path), host=self.ostree)
out_path = pipes.quote(self._prefix_login_path(out_path)) out_path = shlex_quote(self._prefix_login_path(out_path))
try: try:
with open(in_path, 'rb') as in_file: with open(to_bytes(in_path, errors='surrogate_or_strict'),
'rb') as in_file:
try: try:
p = self._buffered_exec_command('dd of=%s bs=%s' % (out_path, BUFSIZE), stdin=in_file) p = self._buffered_exec_command(
'dd of=%s bs=%s' % (out_path, BUFSIZE),
stdin=in_file
)
except OSError: except OSError:
raise AnsibleError("chroot connection requires dd command in the chroot") raise AnsibleError(
"nspawn connection requires dd command in container"
)
try: try:
stdout, stderr = p.communicate() stdout, stderr = p.communicate()
except: except:
traceback.print_exc() traceback.print_exc()
raise AnsibleError("failed to transfer file %s to %s" % (in_path, out_path)) raise AnsibleError("failed to transfer file %s to %s"
% (in_path, out_path))
if p.returncode != 0: if p.returncode != 0:
raise AnsibleError("failed to transfer file %s to %s:\n%s\n%s" % (in_path, out_path, stdout, stderr)) raise AnsibleError(
"failed to transfer file %s to %s:\n%s\n%s"
% (in_path, out_path, stdout, stderr)
)
except IOError: except IOError:
raise AnsibleError("file or module does not exist at: %s" % in_path) raise AnsibleError("file or module does not exist at: %s"
% in_path)
def fetch_file(self, in_path, out_path): def fetch_file(self, in_path, out_path):
''' fetch a file from chroot to local ''' ''' fetch a file from the container to local '''
super(Connection, self).fetch_file(in_path, out_path) super(Connection, self).fetch_file(in_path, out_path)
display.vvv("FETCH %s TO %s" % (in_path, out_path), host=self.chroot) display.vvv("FETCH %s TO %s" % (in_path, out_path), host=self.ostree)
in_path = pipes.quote(self._prefix_login_path(in_path)) in_path = shlex_quote(self._prefix_login_path(in_path))
try: try:
p = self._buffered_exec_command('dd if=%s bs=%s' % (in_path, BUFSIZE)) p = self._buffered_exec_command('dd if=%s bs=%s'
% (in_path, BUFSIZE))
except OSError: except OSError:
raise AnsibleError("chroot connection requires dd command in the chroot") raise AnsibleError(
"nspawn connection requires dd command in the container"
)
with open(out_path, 'wb+') as out_file: with open(to_bytes(out_path, errors='surrogate_or_strict'),
'wb+') as out_file:
try: try:
chunk = p.stdout.read(BUFSIZE) chunk = p.stdout.read(BUFSIZE)
while chunk: while chunk:
@ -141,10 +194,12 @@ class Connection(ConnectionBase):
chunk = p.stdout.read(BUFSIZE) chunk = p.stdout.read(BUFSIZE)
except: except:
traceback.print_exc() traceback.print_exc()
raise AnsibleError("failed to transfer file %s to %s" % (in_path, out_path)) raise AnsibleError("failed to transfer file %s to %s"
% (in_path, out_path))
stdout, stderr = p.communicate() stdout, stderr = p.communicate()
if p.returncode != 0: if p.returncode != 0:
raise AnsibleError("failed to transfer file %s to %s:\n%s\n%s" % (in_path, out_path, stdout, stderr)) raise AnsibleError("failed to transfer file %s to %s:\n%s\n%s"
% (in_path, out_path, stdout, stderr))
def close(self): def close(self):
''' terminate the connection; nothing to do here ''' ''' terminate the connection; nothing to do here '''