path: root/lib/ansible/plugins/connection/paramiko_ssh.py

# (c) 2012, Michael DeHaan <michael.dehaan@gmail.com>
# (c) 2017 Ansible Project
# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type

DOCUMENTATION = """
    author: Ansible Core Team
    connection: paramiko
    short_description: Run tasks via python ssh (paramiko)
    description:
        - Use the python ssh implementation (Paramiko) to connect to targets
        - The paramiko transport is provided because many distributions, in particular EL6 and before do not support ControlPersist
          in their SSH implementations.
        - This is needed on the Ansible control machine to be reasonably efficient with connections.
          Thus paramiko is faster for most users on these platforms.
          Users with ControlPersist capability can consider using -c ssh or configuring the transport in the configuration file.
    version_added: "0.1"
    options:
      remote_addr:
        description:
            - Address of the remote target
        default: inventory_hostname
        vars:
            - name: ansible_host
            - name: ansible_ssh_host
            - name: ansible_paramiko_host
      remote_user:
        description:
            - User to login/authenticate as
        vars:
            - name: ansible_user
            - name: ansible_ssh_user
            - name: ansible_paramiko_user
# TODO:
#getattr(self._play_context, 'ssh_extra_args', '') or '',
#getattr(self._play_context, 'ssh_common_args', '') or '',
#getattr(self._play_context, 'ssh_args', '') or '',
#C.HOST_KEY_CHECKING
#C.PARAMIKO_HOST_KEY_AUTO_ADD
#C.USE_PERSISTENT_CONNECTIONS:
#            ssh.connect(
#                look_for_keys=C.PARAMIKO_LOOK_FOR_KEYS,
#                key_filename,
#                password=self._play_context.password,
#                timeout=self._play_context.timeout,
#                port=port,
#proxy_command = proxy_command or C.PARAMIKO_PROXY_COMMAND
#C.PARAMIKO_PTY
#C.PARAMIKO_RECORD_HOST_KEYS
"""

import warnings
import os
import socket
import tempfile
import traceback
import fcntl
import sys
import re

from termios import tcflush, TCIFLUSH
from binascii import hexlify

from ansible import constants as C
from ansible.errors import AnsibleError, AnsibleConnectionFailure, AnsibleFileNotFound
from ansible.module_utils.six import iteritems
from ansible.module_utils.six.moves import input
from ansible.plugins.connection import ConnectionBase
from ansible.utils.path import makedirs_safe
from ansible.module_utils._text import to_bytes, to_native

try:
    from __main__ import display
except ImportError:
    from ansible.utils.display import Display
    display = Display()


AUTHENTICITY_MSG = """
paramiko: The authenticity of host '%s' can't be established.
The %s key fingerprint is %s.
Are you sure you want to continue connecting (yes/no)?
"""

# SSH Options Regex
SETTINGS_REGEX = re.compile(r'(\w+)(?:\s*=\s*|\s+)(.+)')

# prevent paramiko warning noise -- see http://stackoverflow.com/questions/3920502/
HAVE_PARAMIKO = False
with warnings.catch_warnings():
    warnings.simplefilter("ignore")
    try:
        import paramiko
        HAVE_PARAMIKO = True
    except ImportError:
        pass


class MyAddPolicy(object):
    """
    Based on AutoAddPolicy in paramiko so we can determine when keys are added

    and also prompt for input.

    Policy for automatically adding the hostname and new host key to the
    local L{HostKeys} object, and saving it.  This is used by L{SSHClient}.
    """

    def __init__(self, new_stdin, connection):
        self._new_stdin = new_stdin
        self.connection = connection

    def missing_host_key(self, client, hostname, key):

        if all((C.HOST_KEY_CHECKING, not C.PARAMIKO_HOST_KEY_AUTO_ADD)):

            fingerprint = hexlify(key.get_fingerprint())
            ktype = key.get_name()

            if C.USE_PERSISTENT_CONNECTIONS:
                # don't print the prompt string since the user cannot respond
                # to the question anyway
                raise AnsibleError(AUTHENTICITY_MSG[1:92] % (hostname, ktype, fingerprint))

            self.connection.connection_lock()

            old_stdin = sys.stdin
            sys.stdin = self._new_stdin

            # clear out any premature input on sys.stdin
            tcflush(sys.stdin, TCIFLUSH)

            inp = input(AUTHENTICITY_MSG % (hostname, ktype, fingerprint))
            sys.stdin = old_stdin

            self.connection.connection_unlock()

            if inp not in ['yes', 'y', '']:
                raise AnsibleError("host connection rejected by user")

        key._added_by_ansible_this_time = True

        # existing implementation below:
        client._host_keys.add(hostname, key.get_name(), key)

        # host keys are actually saved in close() function below
        # in order to control ordering.


# keep connection objects on a per host basis to avoid repeated attempts to reconnect

SSH_CONNECTION_CACHE = {}
SFTP_CONNECTION_CACHE = {}


class Connection(ConnectionBase):
    ''' SSH based connections with Paramiko '''

    transport = 'paramiko'

    def _cache_key(self):
        return "%s__%s__" % (self._play_context.remote_addr, self._play_context.remote_user)

    def _connect(self):
        cache_key = self._cache_key()
        if cache_key in SSH_CONNECTION_CACHE:
            self.ssh = SSH_CONNECTION_CACHE[cache_key]
        else:
            self.ssh = SSH_CONNECTION_CACHE[cache_key] = self._connect_uncached()
        return self

    def _parse_proxy_command(self, port=22):
        proxy_command = None
        # Parse ansible_ssh_common_args, specifically looking for ProxyCommand
        ssh_args = [
            getattr(self._play_context, 'ssh_extra_args', '') or '',
            getattr(self._play_context, 'ssh_common_args', '') or '',
            getattr(self._play_context, 'ssh_args', '') or '',
        ]
        if ssh_args is not None:
            args = self._split_ssh_args(' '.join(ssh_args))
            for i, arg in enumerate(args):
                if arg.lower() == 'proxycommand':
                    # _split_ssh_args split ProxyCommand from the command itself
                    proxy_command = args[i + 1]
                else:
                    # ProxyCommand and the command itself are a single string
                    match = SETTINGS_REGEX.match(arg)
                    if match:
                        if match.group(1).lower() == 'proxycommand':
                            proxy_command = match.group(2)

                if proxy_command:
                    break

        proxy_command = proxy_command or C.PARAMIKO_PROXY_COMMAND

        sock_kwarg = {}
        if proxy_command:
            replacers = {
                '%h': self._play_context.remote_addr,
                '%p': port,
                '%r': self._play_context.remote_user
            }
            for find, replace in replacers.items():
                proxy_command = proxy_command.replace(find, str(replace))
            try:
                sock_kwarg = {'sock': paramiko.ProxyCommand(proxy_command)}
                display.vvv("CONFIGURE PROXY COMMAND FOR CONNECTION: %s" % proxy_command, host=self._play_context.remote_addr)
            except AttributeError:
                display.warning('Paramiko ProxyCommand support unavailable. '
                                'Please upgrade to Paramiko 1.9.0 or newer. '
                                'Not using configured ProxyCommand')

        return sock_kwarg

    def _connect_uncached(self):
        ''' activates the connection object '''

        if not HAVE_PARAMIKO:
            raise AnsibleError("paramiko is not installed")

        port = self._play_context.port or 22
        display.vvv("ESTABLISH CONNECTION FOR USER: %s on PORT %s TO %s" % (self._play_context.remote_user, port, self._play_context.remote_addr),
                    host=self._play_context.remote_addr)

        ssh = paramiko.SSHClient()

        self.keyfile = os.path.expanduser("~/.ssh/known_hosts")

        if C.HOST_KEY_CHECKING:
            for ssh_known_hosts in ("/etc/ssh/ssh_known_hosts", "/etc/openssh/ssh_known_hosts"):
                try:
                    # TODO: check if we need to look at several possible locations, possible for loop
                    ssh.load_system_host_keys(ssh_known_hosts)
                    break
                except IOError:
                    pass  # file was not found, but not required to function
            ssh.load_system_host_keys()

        sock_kwarg = self._parse_proxy_command(port)

        ssh.set_missing_host_key_policy(MyAddPolicy(self._new_stdin, self))

        allow_agent = True

        if self._play_context.password is not None:
            allow_agent = False

        try:
            key_filename = None
            if self._play_context.private_key_file:
                key_filename = os.path.expanduser(self._play_context.private_key_file)

            ssh.connect(
                self._play_context.remote_addr,
                username=self._play_context.remote_user,
                allow_agent=allow_agent,
                look_for_keys=C.PARAMIKO_LOOK_FOR_KEYS,
                key_filename=key_filename,
                password=self._play_context.password,
                timeout=self._play_context.timeout,
                port=port,
                **sock_kwarg
            )
        except paramiko.ssh_exception.BadHostKeyException as e:
            raise AnsibleConnectionFailure('host key mismatch for %s' % e.hostname)
        except Exception as e:
            msg = str(e)
            if "PID check failed" in msg:
                raise AnsibleError("paramiko version issue, please upgrade paramiko on the machine running ansible")
            elif "Private key file is encrypted" in msg:
                msg = 'ssh %s@%s:%s : %s\nTo connect as a different user, use -u <username>.' % (
                    self._play_context.remote_user, self._play_context.remote_addr, port, msg)
                raise AnsibleConnectionFailure(msg)
            else:
                raise AnsibleConnectionFailure(msg)

        return ssh

    def exec_command(self, cmd, in_data=None, sudoable=True):
        ''' run a command on the remote host '''

        super(Connection, self).exec_command(cmd, in_data=in_data, sudoable=sudoable)

        if in_data:
            raise AnsibleError("Internal Error: this module does not support optimized module pipelining")

        bufsize = 4096

        try:
            self.ssh.get_transport().set_keepalive(5)
            chan = self.ssh.get_transport().open_session()
        except Exception as e:
            msg = "Failed to open session"
            if len(str(e)) > 0:
                msg += ": %s" % str(e)
            raise AnsibleConnectionFailure(msg)

        # sudo usually requires a PTY (cf. requiretty option), therefore
        # we give it one by default (pty=True in ansble.cfg), and we try
        # to initialise from the calling environment when sudoable is enabled
        if C.PARAMIKO_PTY and sudoable:
            chan.get_pty(term=os.getenv('TERM', 'vt100'), width=int(os.getenv('COLUMNS', 0)), height=int(os.getenv('LINES', 0)))

        display.vvv("EXEC %s" % cmd, host=self._play_context.remote_addr)

        cmd = to_bytes(cmd, errors='surrogate_or_strict')

        no_prompt_out = b''
        no_prompt_err = b''
        become_output = b''

        try:
            chan.exec_command(cmd)
            if self._play_context.prompt:
                passprompt = False
                become_sucess = False
                while not (become_sucess or passprompt):
                    display.debug('Waiting for Privilege Escalation input')

                    chunk = chan.recv(bufsize)
                    display.debug("chunk is: %s" % chunk)
                    if not chunk:
                        if b'unknown user' in become_output:
                            raise AnsibleError('user %s does not exist' % self._play_context.become_user)
                        else:
                            break
                            # raise AnsibleError('ssh connection closed waiting for password prompt')
                    become_output += chunk

                    # need to check every line because we might get lectured
                    # and we might get the middle of a line in a chunk
                    for l in become_output.splitlines(True):
                        if self.check_become_success(l):
                            become_sucess = True
                            break
                        elif self.check_password_prompt(l):
                            passprompt = True
                            break

                if passprompt:
                    if self._play_context.become and self._play_context.become_pass:
                        chan.sendall(to_bytes(self._play_context.become_pass) + b'\n')
                    else:
                        raise AnsibleError("A password is reqired but none was supplied")
                else:
                    no_prompt_out += become_output
                    no_prompt_err += become_output
        except socket.timeout:
            raise AnsibleError('ssh timed out waiting for privilege escalation.\n' + become_output)

        stdout = b''.join(chan.makefile('rb', bufsize))
        stderr = b''.join(chan.makefile_stderr('rb', bufsize))

        return (chan.recv_exit_status(), no_prompt_out + stdout, no_prompt_out + stderr)

    def put_file(self, in_path, out_path):
        ''' transfer a file from local to remote '''

        super(Connection, self).put_file(in_path, out_path)

        display.vvv("PUT %s TO %s" % (in_path, out_path), host=self._play_context.remote_addr)

        if not os.path.exists(to_bytes(in_path, errors='surrogate_or_strict')):
            raise AnsibleFileNotFound("file or module does not exist: %s" % in_path)

        try:
            self.sftp = self.ssh.open_sftp()
        except Exception as e:
            raise AnsibleError("failed to open a SFTP connection (%s)" % e)

        try:
            self.sftp.put(to_bytes(in_path, errors='surrogate_or_strict'), to_bytes(out_path, errors='surrogate_or_strict'))
        except IOError:
            raise AnsibleError("failed to transfer file to %s" % out_path)

    def _connect_sftp(self):

        cache_key = "%s__%s__" % (self._play_context.remote_addr, self._play_context.remote_user)
        if cache_key in SFTP_CONNECTION_CACHE:
            return SFTP_CONNECTION_CACHE[cache_key]
        else:
            result = SFTP_CONNECTION_CACHE[cache_key] = self._connect().ssh.open_sftp()
            return result

    def fetch_file(self, in_path, out_path):
        ''' save a remote file to the specified path '''

        super(Connection, self).fetch_file(in_path, out_path)

        display.vvv("FETCH %s TO %s" % (in_path, out_path), host=self._play_context.remote_addr)

        try:
            self.sftp = self._connect_sftp()
        except Exception as e:
            raise AnsibleError("failed to open a SFTP connection (%s)" % to_native(e))

        try:
            self.sftp.get(to_bytes(in_path, errors='surrogate_or_strict'), to_bytes(out_path, errors='surrogate_or_strict'))
        except IOError:
            raise AnsibleError("failed to transfer file from %s" % in_path)

    def _any_keys_added(self):

        for hostname, keys in iteritems(self.ssh._host_keys):
            for keytype, key in iteritems(keys):
                added_this_time = getattr(key, '_added_by_ansible_this_time', False)
                if added_this_time:
                    return True
        return False

    def _save_ssh_host_keys(self, filename):
        '''
        not using the paramiko save_ssh_host_keys function as we want to add new SSH keys at the bottom so folks
        don't complain about it :)
        '''

        if not self._any_keys_added():
            return False

        path = os.path.expanduser("~/.ssh")
        makedirs_safe(path)

        f = open(filename, 'w')

        for hostname, keys in iteritems(self.ssh._host_keys):

            for keytype, key in iteritems(keys):

                # was f.write
                added_this_time = getattr(key, '_added_by_ansible_this_time', False)
                if not added_this_time:
                    f.write("%s %s %s\n" % (hostname, keytype, key.get_base64()))

        for hostname, keys in iteritems(self.ssh._host_keys):

            for keytype, key in iteritems(keys):
                added_this_time = getattr(key, '_added_by_ansible_this_time', False)
                if added_this_time:
                    f.write("%s %s %s\n" % (hostname, keytype, key.get_base64()))

        f.close()

    def close(self):
        ''' terminate the connection '''

        cache_key = self._cache_key()
        SSH_CONNECTION_CACHE.pop(cache_key, None)
        SFTP_CONNECTION_CACHE.pop(cache_key, None)

        if hasattr(self, 'sftp'):
            if self.sftp is not None:
                self.sftp.close()

        if C.HOST_KEY_CHECKING and C.PARAMIKO_RECORD_HOST_KEYS and self._any_keys_added():

            # add any new SSH host keys -- warning -- this could be slow
            # (This doesn't acquire the connection lock because it needs
            # to exclude only other known_hosts writers, not connections
            # that are starting up.)
            lockfile = self.keyfile.replace("known_hosts", ".known_hosts.lock")
            dirname = os.path.dirname(self.keyfile)
            makedirs_safe(dirname)

            KEY_LOCK = open(lockfile, 'w')
            fcntl.lockf(KEY_LOCK, fcntl.LOCK_EX)

            try:
                # just in case any were added recently

                self.ssh.load_system_host_keys()
                self.ssh._host_keys.update(self.ssh._system_host_keys)

                # gather information about the current key file, so
                # we can ensure the new file has the correct mode/owner

                key_dir = os.path.dirname(self.keyfile)
                if os.path.exists(self.keyfile):
                    key_stat = os.stat(self.keyfile)
                    mode = key_stat.st_mode
                    uid = key_stat.st_uid
                    gid = key_stat.st_gid
                else:
                    mode = 33188
                    uid = os.getuid()
                    gid = os.getgid()

                # Save the new keys to a temporary file and move it into place
                # rather than rewriting the file. We set delete=False because
                # the file will be moved into place rather than cleaned up.

                tmp_keyfile = tempfile.NamedTemporaryFile(dir=key_dir, delete=False)
                os.chmod(tmp_keyfile.name, mode & 0o7777)
                os.chown(tmp_keyfile.name, uid, gid)

                self._save_ssh_host_keys(tmp_keyfile.name)
                tmp_keyfile.close()

                os.rename(tmp_keyfile.name, self.keyfile)

            except:

                # unable to save keys, including scenario when key was invalid
                # and caught earlier
                traceback.print_exc()
            fcntl.lockf(KEY_LOCK, fcntl.LOCK_UN)

        self.ssh.close()