root / lib / ssh.py @ cff4c037
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# Copyright (C) 2006, 2007 Google Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301, USA.
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"""Module encapsulating ssh functionality.
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"""
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import os |
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from ganeti import utils |
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from ganeti import errors |
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from ganeti import constants |
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def GetUserFiles(user, mkdir=False): |
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"""Return the paths of a user's ssh files.
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The function will return a triplet (priv_key_path, pub_key_path,
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auth_key_path) that are used for ssh authentication. Currently, the
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keys used are DSA keys, so this function will return:
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(~user/.ssh/id_dsa, ~user/.ssh/id_dsa.pub,
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~user/.ssh/authorized_keys).
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If the optional parameter mkdir is True, the ssh directory will be
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created if it doesn't exist.
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Regardless of the mkdir parameters, the script will raise an error
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if ~user/.ssh is not a directory.
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"""
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user_dir = utils.GetHomeDir(user) |
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if not user_dir: |
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raise errors.OpExecError("Cannot resolve home of user %s" % user) |
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ssh_dir = os.path.join(user_dir, ".ssh")
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if not os.path.lexists(ssh_dir): |
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if mkdir:
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try:
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os.mkdir(ssh_dir, 0700)
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except EnvironmentError, err: |
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raise errors.OpExecError("Can't create .ssh dir for user %s: %s" % |
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(user, str(err)))
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elif not os.path.isdir(ssh_dir): |
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raise errors.OpExecError("path ~%s/.ssh is not a directory" % user) |
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return [os.path.join(ssh_dir, base)
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for base in ["id_dsa", "id_dsa.pub", "authorized_keys"]] |
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class SshRunner: |
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"""Wrapper for SSH commands.
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"""
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def __init__(self, cluster_name): |
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self.cluster_name = cluster_name
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def _BuildSshOptions(self, batch, ask_key, use_cluster_key, |
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strict_host_check): |
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options = [ |
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"-oEscapeChar=none",
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"-oHashKnownHosts=no",
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"-oGlobalKnownHostsFile=%s" % constants.SSH_KNOWN_HOSTS_FILE,
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"-oUserKnownHostsFile=/dev/null",
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] |
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if use_cluster_key:
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options.append("-oHostKeyAlias=%s" % self.cluster_name) |
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# TODO: Too many boolean options, maybe convert them to more descriptive
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# constants.
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# Note: ask_key conflicts with batch mode
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if batch:
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if ask_key:
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raise errors.ProgrammerError("SSH call requested conflicting options") |
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options.append("-oBatchMode=yes")
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if strict_host_check:
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options.append("-oStrictHostKeyChecking=yes")
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else:
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options.append("-oStrictHostKeyChecking=no")
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elif ask_key:
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options.extend([ |
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"-oStrictHostKeyChecking=ask",
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]) |
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return options
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def BuildCmd(self, hostname, user, command, batch=True, ask_key=False, |
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tty=False, use_cluster_key=True, strict_host_check=True): |
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"""Build an ssh command to execute a command on a remote node.
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Args:
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hostname: the target host, string
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user: user to auth as
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command: the command
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batch: if true, ssh will run in batch mode with no prompting
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ask_key: if true, ssh will run with StrictHostKeyChecking=ask, so that
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we can connect to an unknown host (not valid in batch mode)
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use_cluster_key: Whether to expect and use the cluster-global SSH key
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strict_host_check: Whether to check the host's SSH key at all
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Returns:
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The ssh call to run 'command' on the remote host.
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"""
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argv = [constants.SSH, "-q"]
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argv.extend(self._BuildSshOptions(batch, ask_key, use_cluster_key,
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strict_host_check)) |
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if tty:
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argv.append("-t")
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argv.extend(["%s@%s" % (user, hostname), command])
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return argv
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def Run(self, *args, **kwargs): |
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"""Runs a command on a remote node.
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This method has the same return value as `utils.RunCmd()`, which it
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uses to launch ssh.
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Args:
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See SshRunner.BuildCmd.
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Returns:
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`utils.RunResult` like `utils.RunCmd()`
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"""
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return utils.RunCmd(self.BuildCmd(*args, **kwargs)) |
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def CopyFileToNode(self, node, filename): |
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"""Copy a file to another node with scp.
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Args:
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node: node in the cluster
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filename: absolute pathname of a local file
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Returns:
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success: True/False
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"""
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if not os.path.isabs(filename): |
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logging.error("File %s must be an absolute path", filename)
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return False |
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if not os.path.isfile(filename): |
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logging.error("File %s does not exist", filename)
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return False |
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command = [constants.SCP, "-q", "-p"] |
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command.extend(self._BuildSshOptions(True, False, True, True)) |
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command.append(filename) |
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command.append("%s:%s" % (node, filename))
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result = utils.RunCmd(command) |
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if result.failed:
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logging.error("Copy to node %s failed (%s) error %s,"
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" command was %s",
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node, result.fail_reason, result.output, result.cmd) |
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return not result.failed |
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def VerifyNodeHostname(self, node): |
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"""Verify hostname consistency via SSH.
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This functions connects via ssh to a node and compares the hostname
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reported by the node to the name with have (the one that we
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connected to).
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This is used to detect problems in ssh known_hosts files
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(conflicting known hosts) and incosistencies between dns/hosts
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entries and local machine names
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Args:
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node: nodename of a host to check. can be short or full qualified hostname
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Returns:
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(success, detail)
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where
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success: True/False
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detail: String with details
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"""
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retval = self.Run(node, 'root', 'hostname') |
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if retval.failed:
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msg = "ssh problem"
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output = retval.output |
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if output:
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msg += ": %s" % output
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return False, msg |
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remotehostname = retval.stdout.strip() |
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if not remotehostname or remotehostname != node: |
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return False, "hostname mismatch, got %s" % remotehostname |
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return True, "host matches" |
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def WriteKnownHostsFile(cfg, file_name): |
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"""Writes the cluster-wide equally known_hosts file.
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"""
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utils.WriteFile(file_name, mode=0700,
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data="%s ssh-rsa %s\n" % (cfg.GetClusterName(),
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cfg.GetHostKey())) |