Write secrets to tmpfs

So that we may avoid writing the decrypted contents of secrets to
disk, write them to a file in a tmpfs.

Change-Id: I7c029b67d0fc2fa3827dc811137dd4f3a90706d8
changes/49/495449/4
James E. Blair 5 years ago
parent ce56ff9756
commit d6a71ca2b4
  1. 7
      tests/unit/test_bubblewrap.py
  2. 6
      tests/unit/test_v3.py
  3. 5
      zuul/driver/__init__.py
  4. 71
      zuul/driver/bubblewrap/__init__.py
  5. 13
      zuul/driver/nullwrap/__init__.py
  6. 31
      zuul/executor/server.py

@ -39,8 +39,8 @@ class TestBubblewrap(testtools.TestCase):
ssh_agent.start()
po = context.getPopen(work_dir=work_dir,
ssh_auth_sock=ssh_agent.env['SSH_AUTH_SOCK'])
self.assertTrue(po.passwd_r > 2)
self.assertTrue(po.group_r > 2)
self.assertTrue(po.fds[0] > 2)
self.assertTrue(po.fds[1] > 2)
self.assertTrue(work_dir in po.command)
# Now run /usr/bin/id to verify passwd/group entries made it in
true_proc = po(['/usr/bin/id'], stdout=subprocess.PIPE,
@ -51,8 +51,7 @@ class TestBubblewrap(testtools.TestCase):
# And that it did not print things on stderr
self.assertEqual(0, len(errs.strip()))
# Make sure the _r's are closed
self.assertIsNone(po.passwd_r)
self.assertIsNone(po.group_r)
self.assertEqual([], po.fds)
def test_bubblewrap_leak(self):
bwrap = bubblewrap.BubblewrapDriver()

@ -1283,8 +1283,7 @@ class TestSecretLeaks(AnsibleZuulTestCase):
], ordered=False)
matches = self.searchForContent(self.history[0].jobdir.root,
b'test-password')
self.assertEqual(set(['/ansible/playbook_0/secrets.yaml',
'/work/secret-file.txt']),
self.assertEqual(set(['/work/secret-file.txt']),
set(matches))
def test_secret_file(self):
@ -1319,8 +1318,7 @@ class TestSecretLeaks(AnsibleZuulTestCase):
], ordered=False)
matches = self.searchForContent(self.history[0].jobdir.root,
b'test-password')
self.assertEqual(set(['/ansible/playbook_0/secrets.yaml',
'/work/failure-file.txt']),
self.assertEqual(set(['/work/failure-file.txt']),
set(matches))
def test_secret_file_fail(self):

@ -258,7 +258,7 @@ class WrapperInterface(object, metaclass=abc.ABCMeta):
"""
@abc.abstractmethod
def getExecutionContext(self, ro_paths=None, rw_paths=None):
def getExecutionContext(self, ro_paths=None, rw_paths=None, secrets=None):
"""Create and return an execution context.
The execution context is meant to be used for a single
@ -268,6 +268,9 @@ class WrapperInterface(object, metaclass=abc.ABCMeta):
:arg list ro_paths: read only files or directories to bind mount
:arg list rw_paths: read write files or directories to bind mount
:arg dict secrets: a dictionary where the key is a file path,
and the value is the content which should be written to
that path in a secure manner.
:returns: a new ExecutionContext object.
:rtype: BaseExecutionContext

@ -22,6 +22,7 @@ import pwd
import shlex
import subprocess
import sys
import threading
import re
from typing import Dict, List # flake8: noqa
@ -31,10 +32,9 @@ from zuul.execution_context import BaseExecutionContext
class WrappedPopen(object):
def __init__(self, command, passwd_r, group_r):
def __init__(self, command, fds):
self.command = command
self.passwd_r = passwd_r
self.group_r = group_r
self.fds = fds
def __call__(self, args, *sub_args, **kwargs):
try:
@ -46,7 +46,7 @@ class WrappedPopen(object):
# versions. So until we are py3 only we can only bwrap
# things that are close_fds=False
pass_fds = list(kwargs.get('pass_fds', []))
for fd in (self.passwd_r, self.group_r):
for fd in self.fds:
if fd not in pass_fds:
pass_fds.append(fd)
kwargs['pass_fds'] = pass_fds
@ -56,26 +56,32 @@ class WrappedPopen(object):
return proc
def __del__(self):
if self.passwd_r:
for fd in self.fds:
try:
os.close(self.passwd_r)
os.close(fd)
except OSError:
pass
self.passwd_r = None
if self.group_r:
try:
os.close(self.group_r)
except OSError:
pass
self.group_r = None
self.fds = []
class BubblewrapExecutionContext(BaseExecutionContext):
log = logging.getLogger("zuul.BubblewrapExecutionContext")
def __init__(self, bwrap_command, ro_paths, rw_paths):
def __init__(self, bwrap_command, ro_paths, rw_paths, secrets):
self.bwrap_command = bwrap_command
self.mounts_map = {'ro': ro_paths, 'rw': rw_paths}
self.secrets = secrets
def startPipeWriter(self, pipe, data):
# In case we have a large amount of data to write through a
# pipe, spawn a thread to handle the writes.
t = threading.Thread(target=self._writer, args=(pipe, data))
t.daemon = True
t.start()
def _writer(self, pipe, data):
os.write(pipe, data)
os.close(pipe)
def getPopen(self, **kwargs):
# Set zuul_dir if it was not passed in
@ -95,6 +101,9 @@ class BubblewrapExecutionContext(BaseExecutionContext):
for bind in self.mounts_map[mount_type]:
bwrap_command.extend([bind_arg, bind, bind])
# A list of file descriptors which must be held open so that
# bwrap may read from them.
read_fds = []
# Need users and groups
uid = os.getuid()
passwd = list(pwd.getpwuid(uid))
@ -106,6 +115,7 @@ class BubblewrapExecutionContext(BaseExecutionContext):
os.write(passwd_w, passwd_bytes)
os.write(passwd_w, b'\n')
os.close(passwd_w)
read_fds.append(passwd_r)
gid = os.getgid()
group = grp.getgrgid(gid)
@ -115,6 +125,20 @@ class BubblewrapExecutionContext(BaseExecutionContext):
os.write(group_w, group_bytes)
os.write(group_w, b'\n')
os.close(group_w)
read_fds.append(group_r)
# Create a tmpfs for each directory which holds secrets, and
# tell bubblewrap to write the contents to a file therein.
secret_dirs = set()
for fn, content in self.secrets.items():
secret_dir = os.path.dirname(fn)
if secret_dir not in secret_dirs:
bwrap_command.extend(['--tmpfs', secret_dir])
secret_dirs.add(secret_dir)
secret_r, secret_w = os.pipe()
self.startPipeWriter(secret_w, content.encode('utf8'))
bwrap_command.extend(['--file', str(secret_r), fn])
read_fds.append(secret_r)
kwargs = dict(kwargs) # Don't update passed in dict
kwargs['uid'] = uid
@ -126,7 +150,7 @@ class BubblewrapExecutionContext(BaseExecutionContext):
self.log.debug("Bubblewrap command: %s",
" ".join(shlex.quote(c) for c in command))
wrapped_popen = WrappedPopen(command, passwd_r, group_r)
wrapped_popen = WrappedPopen(command, read_fds)
return wrapped_popen
@ -186,14 +210,17 @@ class BubblewrapDriver(Driver, WrapperInterface):
return bwrap_command
def getExecutionContext(self, ro_paths=None, rw_paths=None):
def getExecutionContext(self, ro_paths=None, rw_paths=None, secrets=None):
if not ro_paths:
ro_paths = []
if not rw_paths:
rw_paths = []
if not secrets:
secrets = {}
return BubblewrapExecutionContext(
self.bwrap_command,
ro_paths, rw_paths)
ro_paths, rw_paths,
secrets)
def main(args=None):
@ -204,14 +231,22 @@ def main(args=None):
parser = argparse.ArgumentParser()
parser.add_argument('--ro-paths', nargs='+')
parser.add_argument('--rw-paths', nargs='+')
parser.add_argument('--secret', nargs='+')
parser.add_argument('work_dir')
parser.add_argument('run_args', nargs='+')
cli_args = parser.parse_args()
ssh_auth_sock = os.environ.get('SSH_AUTH_SOCK')
secrets = {}
if cli_args.secret:
for secret in cli_args.secret:
fn, content = secret.split('=', 1)
secrets[fn]=content
context = driver.getExecutionContext(
cli_args.ro_paths, cli_args.rw_paths)
cli_args.ro_paths, cli_args.rw_paths,
secrets)
popen = context.getPopen(work_dir=cli_args.work_dir,
ssh_auth_sock=ssh_auth_sock)

@ -32,5 +32,16 @@ class NullwrapDriver(Driver, WrapperInterface):
name = 'nullwrap'
log = logging.getLogger("zuul.NullwrapDriver")
def getExecutionContext(self, ro_paths=None, rw_paths=None):
def getExecutionContext(self, ro_paths=None, rw_paths=None, secrets=None):
# The bubblewrap driver writes secrets to a tmpfs so that they
# don't hit the disk (unless the kernel swaps the memory to
# disk, which can be mitigated with encrypted swap). We
# haven't implemented similar functionality in nullwrap, so
# for safety, raise an exception in that case. If you are
# interested in implementing this functionality, please
# contact us on the mailing list.
if secrets:
raise NotImplementedError(
"The nullwrap driver does not support the use of secrets. "
"Consider using the bubblewrap driver instead.")
return NullExecutionContext()

@ -255,8 +255,9 @@ class JobDirPlaybook(object):
self.roles_path = []
self.ansible_config = os.path.join(self.root, 'ansible.cfg')
self.project_link = os.path.join(self.root, 'project')
self.secrets = os.path.join(self.root, 'secrets.yaml')
self.has_secrets = False
self.secrets_root = os.path.join(self.root, 'secrets')
self.secrets = os.path.join(self.secrets_root, 'secrets.yaml')
self.secrets_content = None
def addRole(self):
count = len(self.roles)
@ -1266,6 +1267,13 @@ class AnsibleJob(object):
for role in playbook['roles']:
self.prepareRole(jobdir_playbook, role, args)
secrets = playbook['secrets']
if secrets:
if 'zuul' in secrets:
raise Exception("Defining secrets named 'zuul' is not allowed")
jobdir_playbook.secrets_content = yaml.safe_dump(
secrets, default_flow_style=False)
self.writeAnsibleConfig(jobdir_playbook, playbook)
def checkoutTrustedProject(self, project, branch):
@ -1390,15 +1398,6 @@ class AnsibleJob(object):
def writeAnsibleConfig(self, jobdir_playbook, playbook):
trusted = jobdir_playbook.trusted
secrets = playbook['secrets'].copy()
if secrets:
if 'zuul' in secrets:
raise Exception("Defining secrets named 'zuul' is not allowed")
with open(jobdir_playbook.secrets, 'w') as secrets_yaml:
secrets_yaml.write(
yaml.safe_dump(secrets, default_flow_style=False))
jobdir_playbook.has_secrets = True
# TODO(mordred) This should likely be extracted into a more generalized
# mechanism for deployers being able to add callback
# plugins.
@ -1441,7 +1440,7 @@ class AnsibleJob(object):
# role. Otherwise, printing the args could be useful for
# debugging.
config.write('display_args_to_stdout = %s\n' %
str(not secrets))
str(not playbook['secrets']))
config.write('[ssh_connection]\n')
# NB: when setting pipelining = True, keep_remote_files
@ -1509,8 +1508,12 @@ class AnsibleJob(object):
if self.executor_variables_file:
ro_paths.append(self.executor_variables_file)
secrets = {}
if playbook.secrets_content:
secrets[playbook.secrets] = playbook.secrets_content
context = self.executor_server.execution_wrapper.getExecutionContext(
ro_paths, rw_paths)
ro_paths, rw_paths, secrets)
popen = context.getPopen(
work_dir=self.jobdir.work_root,
@ -1593,7 +1596,7 @@ class AnsibleJob(object):
verbose = '-v'
cmd = ['ansible-playbook', verbose, playbook.path]
if playbook.has_secrets:
if playbook.secrets_content:
cmd.extend(['-e', '@' + playbook.secrets])
if success is not None:

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