# Copyright 2017, David Wilson # # Redistribution and use in source and binary forms, with or without # modification, are permitted provided that the following conditions are met: # # 1. Redistributions of source code must retain the above copyright notice, # this list of conditions and the following disclaimer. # # 2. Redistributions in binary form must reproduce the above copyright notice, # this list of conditions and the following disclaimer in the documentation # and/or other materials provided with the distribution. # # 3. Neither the name of the copyright holder nor the names of its contributors # may be used to endorse or promote products derived from this software without # specific prior written permission. # # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE # ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE # LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR # CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF # SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS # INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN # CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) # ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE # POSSIBILITY OF SUCH DAMAGE. """ Helper functions intended to be executed on the target. These are entrypoints for file transfer, module execution and sundry bits like changing file modes. """ from __future__ import absolute_import from __future__ import unicode_literals import errno import functools import grp import json import logging import operator import os import pwd import re import resource import signal import stat import subprocess import sys import tempfile import traceback import types import mitogen.core import mitogen.fork import mitogen.parent import mitogen.service # Ansible since PR #41749 inserts "import __main__" into # ansible.module_utils.basic. Mitogen's importer will refuse such an import, so # we must setup a fake "__main__" before that module is ever imported. The # str() is to cast Unicode to bytes on Python 2.6. if not sys.modules.get(str('__main__')): sys.modules[str('__main__')] = types.ModuleType(str('__main__')) import ansible.module_utils.json_utils import ansible_mitogen.runner LOG = logging.getLogger(__name__) MAKE_TEMP_FAILED_MSG = ( "Unable to find a useable temporary directory. This likely means no\n" "system-supplied TMP directory can be written to, or all directories\n" "were mounted on 'noexec' filesystems.\n" "\n" "The following paths were tried:\n" " %(namelist)s\n" "\n" "Please check '-vvv' output for a log of individual path errors." ) #: Initialized to an econtext.parent.Context pointing at a pristine fork of #: the target Python interpreter before it executes any code or imports. _fork_parent = None #: Set by :func:`init_child` to the name of a writeable and executable #: temporary directory accessible by the active user account. good_temp_dir = None # issue #362: subprocess.Popen(close_fds=True) aka. AnsibleModule.run_command() # loops the entire SC_OPEN_MAX space. CentOS>5 ships with 1,048,576 FDs by # default, resulting in huge (>500ms) runtime waste running many commands. # Therefore if we are a child, cap the range to something reasonable. rlimit = resource.getrlimit(resource.RLIMIT_NOFILE) if (rlimit[0] > 512 or rlimit[1] > 512) and not mitogen.is_master: resource.setrlimit(resource.RLIMIT_NOFILE, (512, 512)) subprocess.MAXFD = 512 # Python <3.x del rlimit def get_small_file(context, path): """ Basic in-memory caching module fetcher. This generates an one roundtrip for every previously unseen file, so it is only a temporary solution. :param context: Context we should direct FileService requests to. For now (and probably forever) this is just the top-level Mitogen connection manager process. :param path: Path to fetch from FileService, must previously have been registered by a privileged context using the `register` command. :returns: Bytestring file data. """ pool = mitogen.service.get_or_create_pool(router=context.router) service = pool.get_service('mitogen.service.PushFileService') return service.get(path) def transfer_file(context, in_path, out_path, sync=False, set_owner=False): """ Streamily download a file from the connection multiplexer process in the controller. :param mitogen.core.Context context: Reference to the context hosting the FileService that will be used to fetch the file. :param bytes in_path: FileService registered name of the input file. :param bytes out_path: Name of the output path on the local disk. :param bool sync: If :data:`True`, ensure the file content and metadat are fully on disk before renaming the temporary file over the existing file. This should ensure in the case of system crash, either the entire old or new file are visible post-reboot. :param bool set_owner: If :data:`True`, look up the metadata username and group on the local system and file the file owner using :func:`os.fchmod`. """ out_path = os.path.abspath(out_path) fd, tmp_path = tempfile.mkstemp(suffix='.tmp', prefix='.ansible_mitogen_transfer-', dir=os.path.dirname(out_path)) fp = os.fdopen(fd, 'wb', mitogen.core.CHUNK_SIZE) LOG.debug('transfer_file(%r) temporary file: %s', out_path, tmp_path) try: try: ok, metadata = mitogen.service.FileService.get( context=context, path=in_path, out_fp=fp, ) if not ok: raise IOError('transfer of %r was interrupted.' % (in_path,)) os.fchmod(fp.fileno(), metadata['mode']) if set_owner: set_fd_owner(fp.fileno(), metadata['owner'], metadata['group']) finally: fp.close() if sync: os.fsync(fp.fileno()) os.rename(tmp_path, out_path) except BaseException: os.unlink(tmp_path) raise os.utime(out_path, (metadata['atime'], metadata['mtime'])) def prune_tree(path): """ Like shutil.rmtree(), but log errors rather than discard them, and do not waste multiple os.stat() calls discovering whether the object can be deleted, just try deleting it instead. """ try: os.unlink(path) return except OSError as e: if not (os.path.isdir(path) and e.args[0] in (errno.EPERM, errno.EISDIR)): LOG.error('prune_tree(%r): %s', path, e) return try: # Ensure write access for readonly directories. Ignore error in case # path is on a weird filesystem (e.g. vfat). os.chmod(path, int('0700', 8)) except OSError as e: LOG.warning('prune_tree(%r): %s', path, e) try: for name in os.listdir(path): if name not in ('.', '..'): prune_tree(os.path.join(path, name)) os.rmdir(path) except OSError as e: LOG.error('prune_tree(%r): %s', path, e) def _on_broker_shutdown(): """ Respond to broker shutdown (graceful termination by parent, or loss of connection to parent) by deleting our sole temporary directory. """ prune_tree(temp_dir) def is_good_temp_dir(path): """ Return :data:`True` if `path` can be used as a temporary directory, logging any failures that may cause it to be unsuitable. If the directory doesn't exist, we attempt to create it using :func:`os.makedirs`. """ if not os.path.exists(path): try: os.makedirs(path, mode=int('0700', 8)) except OSError as e: LOG.debug('temp dir %r unusable: did not exist and attempting ' 'to create it failed: %s', path, e) return False try: tmp = tempfile.NamedTemporaryFile( prefix='ansible_mitogen_is_good_temp_dir', dir=path, ) except (OSError, IOError) as e: LOG.debug('temp dir %r unusable: %s', path, e) return False try: try: os.chmod(tmp.name, int('0700', 8)) except OSError as e: LOG.debug('temp dir %r unusable: chmod failed: %s', path, e) return False try: # access(.., X_OK) is sufficient to detect noexec. if not os.access(tmp.name, os.X_OK): raise OSError('filesystem appears to be mounted noexec') except OSError as e: LOG.debug('temp dir %r unusable: %s', path, e) return False finally: tmp.close() return True def find_good_temp_dir(candidate_temp_dirs): """ Given a list of candidate temp directories extracted from ``ansible.cfg``, combine it with the Python-builtin list of candidate directories used by :mod:`tempfile`, then iteratively try each until one is found that is both writeable and executable. :param list candidate_temp_dirs: List of candidate $variable-expanded and tilde-expanded directory paths that may be usable as a temporary directory. """ paths = [os.path.expandvars(os.path.expanduser(p)) for p in candidate_temp_dirs] paths.extend(tempfile._candidate_tempdir_list()) for path in paths: if is_good_temp_dir(path): LOG.debug('Selected temp directory: %r (from %r)', path, paths) return path raise IOError(MAKE_TEMP_FAILED_MSG % { 'paths': '\n '.join(paths), }) @mitogen.core.takes_econtext def init_child(econtext, log_level, candidate_temp_dirs): """ Called by ContextService immediately after connection; arranges for the (presently) spotless Python interpreter to be forked, where the newly forked interpreter becomes the parent of any newly forked future interpreters. This is necessary to prevent modules that are executed in-process from polluting the global interpreter state in a way that effects explicitly isolated modules. :param int log_level: Logging package level active in the master. :param list[str] candidate_temp_dirs: List of $variable-expanded and tilde-expanded directory names to add to candidate list of temporary directories. :returns: Dict like:: { 'fork_context': mitogen.core.Context. 'home_dir': str. } Where `fork_context` refers to the newly forked 'fork parent' context the controller will use to start forked jobs, and `home_dir` is the home directory for the active user account. """ # Copying the master's log level causes log messages to be filtered before # they reach LogForwarder, thus reducing an influx of tiny messges waking # the connection multiplexer process in the master. LOG.setLevel(log_level) logging.getLogger('ansible_mitogen').setLevel(log_level) global _fork_parent mitogen.parent.upgrade_router(econtext) _fork_parent = econtext.router.fork() global good_temp_dir good_temp_dir = find_good_temp_dir(candidate_temp_dirs) return { 'fork_context': _fork_parent, 'home_dir': mitogen.core.to_text(os.path.expanduser('~')), 'good_temp_dir': good_temp_dir, } @mitogen.core.takes_econtext def create_fork_child(econtext): """ For helper functions executed in the fork parent context, arrange for the context's router to be upgraded as necessary and for a new child to be prepared. """ mitogen.parent.upgrade_router(econtext) context = econtext.router.fork() LOG.debug('create_fork_child() -> %r', context) return context def run_module(kwargs): """ Set up the process environment in preparation for running an Ansible module. This monkey-patches the Ansible libraries in various places to prevent it from trying to kill the process on completion, and to prevent it from reading sys.stdin. """ runner_name = kwargs.pop('runner_name') klass = getattr(ansible_mitogen.runner, runner_name) impl = klass(**kwargs) return impl.run() def _get_async_dir(): return os.path.expanduser( os.environ.get('ANSIBLE_ASYNC_DIR', '~/.ansible_async') ) class AsyncRunner(object): def __init__(self, job_id, timeout_secs, econtext, kwargs): self.job_id = job_id self.timeout_secs = timeout_secs self.econtext = econtext self.kwargs = kwargs self._timed_out = False self._init_path() def _init_path(self): async_dir = _get_async_dir() if not os.path.exists(async_dir): os.makedirs(async_dir) self.path = os.path.join(async_dir, self.job_id) def _update(self, dct): """ Update an async job status file. """ LOG.info('%r._update(%r, %r)', self, self.job_id, dct) dct.setdefault('ansible_job_id', self.job_id) dct.setdefault('data', '') with open(self.path + '.tmp', 'w') as fp: fp.write(json.dumps(dct)) os.rename(self.path + '.tmp', self.path) def _on_sigalrm(self, signum, frame): """ Respond to SIGALRM (job timeout) by updating the job file and killing the process. """ msg = "Job reached maximum time limit of %d seconds." % ( self.timeout_secs, ) self._update({ "failed": 1, "finished": 1, "msg": msg, }) self._timed_out = True self.econtext.broker.shutdown() def _install_alarm(self): signal.signal(signal.SIGALRM, self._on_sigalrm) signal.alarm(self.timeout_secs) def _run_module(self): kwargs = dict(self.kwargs, **{ 'detach': True, 'econtext': self.econtext, 'emulate_tty': False, }) return run_module(kwargs) def _parse_result(self, dct): filtered, warnings = ( ansible.module_utils.json_utils. _filter_non_json_lines(dct['stdout']) ) result = json.loads(filtered) result.setdefault('warnings', []).extend(warnings) result['stderr'] = dct['stderr'] self._update(result) def _run(self): """ 1. Immediately updates the status file to mark the job as started. 2. Installs a timer/signal handler to implement the time limit. 3. Runs as with run_module(), writing the result to the status file. :param dict kwargs: Runner keyword arguments. :param str job_id: String job ID. :param int timeout_secs: If >0, limit the task's maximum run time. """ self._update({ 'started': 1, 'finished': 0, 'pid': os.getpid() }) if self.timeout_secs > 0: self._install_alarm() dct = self._run_module() if not self._timed_out: # After SIGALRM fires, there is a window between broker responding # to shutdown() by killing the process, and work continuing on the # main thread. If main thread was asleep in at least # basic.py/select.select(), an EINTR will be raised. We want to # discard that exception. try: self._parse_result(dct) except Exception: self._update({ "failed": 1, "msg": traceback.format_exc(), "data": dct['stdout'], # temporary notice only "stderr": dct['stderr'] }) def run(self): try: try: self._run() except Exception: self._update({ "failed": 1, "msg": traceback.format_exc(), }) finally: self.econtext.broker.shutdown() @mitogen.core.takes_econtext def run_module_async(kwargs, job_id, timeout_secs, econtext): """ Execute a module with its run status and result written to a file, terminating on the process on completion. This function must run in a child forked using :func:`create_fork_child`. """ arunner = AsyncRunner(job_id, timeout_secs, econtext, kwargs) arunner.run() def get_user_shell(): """ For commands executed directly via an SSH command-line, SSH looks up the user's shell via getpwuid() and only defaults to /bin/sh if that field is missing or empty. """ try: pw_shell = pwd.getpwuid(os.geteuid()).pw_shell except KeyError: pw_shell = None return pw_shell or '/bin/sh' def exec_args(args, in_data='', chdir=None, shell=None, emulate_tty=False): """ Run a command in a subprocess, emulating the argument handling behaviour of SSH. :param list[str]: Argument vector. :param bytes in_data: Optional standard input for the command. :param bool emulate_tty: If :data:`True`, arrange for stdout and stderr to be merged into the stdout pipe and for LF to be translated into CRLF, emulating the behaviour of a TTY. :return: (return code, stdout bytes, stderr bytes) """ LOG.debug('exec_args(%r, ..., chdir=%r)', args, chdir) assert isinstance(args, list) if emulate_tty: stderr = subprocess.STDOUT else: stderr = subprocess.PIPE proc = subprocess.Popen( args=args, stdout=subprocess.PIPE, stderr=stderr, stdin=subprocess.PIPE, cwd=chdir, ) stdout, stderr = proc.communicate(in_data) if emulate_tty: stdout = stdout.replace(b'\n', b'\r\n') return proc.returncode, stdout, stderr or b'' def exec_command(cmd, in_data='', chdir=None, shell=None, emulate_tty=False): """ Run a command in a subprocess, emulating the argument handling behaviour of SSH. :param bytes cmd: String command line, passed to user's shell. :param bytes in_data: Optional standard input for the command. :return: (return code, stdout bytes, stderr bytes) """ assert isinstance(cmd, mitogen.core.UnicodeType) return exec_args( args=[get_user_shell(), '-c', cmd], in_data=in_data, chdir=chdir, shell=shell, emulate_tty=emulate_tty, ) def read_path(path): """ Fetch the contents of a filesystem `path` as bytes. """ return open(path, 'rb').read() def set_fd_owner(fd, owner, group=None): if owner: uid = pwd.getpwnam(owner).pw_uid else: uid = os.geteuid() if group: gid = grp.getgrnam(group).gr_gid else: gid = os.getegid() os.fchown(fd, (uid, gid)) def write_path(path, s, owner=None, group=None, mode=None, utimes=None, sync=False): """ Writes bytes `s` to a filesystem `path`. """ path = os.path.abspath(path) fd, tmp_path = tempfile.mkstemp(suffix='.tmp', prefix='.ansible_mitogen_transfer-', dir=os.path.dirname(path)) fp = os.fdopen(fd, 'wb', mitogen.core.CHUNK_SIZE) LOG.debug('write_path(path=%r) temporary file: %s', path, tmp_path) try: try: if mode: os.fchmod(fp.fileno(), mode) if owner or group: set_fd_owner(fp.fileno(), owner, group) fp.write(s) finally: fp.close() if sync: os.fsync(fp.fileno()) os.rename(tmp_path, path) except BaseException: os.unlink(tmp_path) raise if utimes: os.utime(path, utimes) CHMOD_CLAUSE_PAT = re.compile(r'([uoga]*)([+\-=])([ugo]|[rwx]*)') CHMOD_MASKS = { 'u': stat.S_IRWXU, 'g': stat.S_IRWXG, 'o': stat.S_IRWXO, 'a': (stat.S_IRWXU | stat.S_IRWXG | stat.S_IRWXO), } CHMOD_BITS = { 'u': {'r': stat.S_IRUSR, 'w': stat.S_IWUSR, 'x': stat.S_IXUSR}, 'g': {'r': stat.S_IRGRP, 'w': stat.S_IWGRP, 'x': stat.S_IXGRP}, 'o': {'r': stat.S_IROTH, 'w': stat.S_IWOTH, 'x': stat.S_IXOTH}, 'a': { 'r': (stat.S_IRUSR | stat.S_IRGRP | stat.S_IROTH), 'w': (stat.S_IWUSR | stat.S_IWGRP | stat.S_IWOTH), 'x': (stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH) } } def apply_mode_spec(spec, mode): """ Given a symbolic file mode change specification in the style of chmod(1) `spec`, apply changes in the specification to the numeric file mode `mode`. """ for clause in spec.split(','): match = CHMOD_CLAUSE_PAT.match(clause) who, op, perms = match.groups() for ch in who or 'a': mask = CHMOD_MASKS[ch] bits = CHMOD_BITS[ch] cur_perm_bits = mode & mask new_perm_bits = functools.reduce(operator.or_, (bits[p] for p in perms), 0) mode &= ~mask if op == '=': mode |= new_perm_bits elif op == '+': mode |= new_perm_bits | cur_perm_bits else: mode |= cur_perm_bits & ~new_perm_bits return mode def set_file_mode(path, spec): """ Update the permissions of a file using the same syntax as chmod(1). """ mode = os.stat(path).st_mode if spec.isdigit(): new_mode = int(spec, 8) else: new_mode = apply_mode_spec(spec, mode) os.chmod(path, new_mode)