X-Git-Url: https://code.grnet.gr/git/ganeti-local/blobdiff_plain/3ecf6786a731c0a467f0efcbf6346914e3824ec8..944bf54895c1d4491c6d06ad464aa6e97844c366:/lib/ssh.py?ds=sidebyside diff --git a/lib/ssh.py b/lib/ssh.py index 9e4413a..40df999 100644 --- a/lib/ssh.py +++ b/lib/ssh.py @@ -1,4 +1,4 @@ -#!/usr/bin/python +# # # Copyright (C) 2006, 2007 Google Inc. @@ -25,106 +25,217 @@ import os +import logging -from ganeti import logger from ganeti import utils from ganeti import errors +from ganeti import constants + -def SSHCall(hostname, user, command, batch=True, ask_key=False): - """Execute a command on a remote node. +def GetUserFiles(user, mkdir=False): + """Return the paths of a user's ssh files. - This method has the same return value as `utils.RunCmd()`, which it - uses to launch ssh. + The function will return a triplet (priv_key_path, pub_key_path, + auth_key_path) that are used for ssh authentication. Currently, the + keys used are DSA keys, so this function will return: + (~user/.ssh/id_dsa, ~user/.ssh/id_dsa.pub, + ~user/.ssh/authorized_keys). - Args: - hostname: the target host, string - user: user to auth as - command: the command + If the optional parameter mkdir is True, the ssh directory will be + created if it doesn't exist. - Returns: - `utils.RunResult` as for `utils.RunCmd()` + Regardless of the mkdir parameters, the script will raise an error + if ~user/.ssh is not a directory. """ - argv = ["ssh", "-q", "-oEscapeChar=none"] - if batch: - argv.append("-oBatchMode=yes") - # if we are in batch mode, we can't ask the key - if ask_key: - raise errors.ProgrammerError("SSH call requested conflicting options") - if ask_key: - argv.append("-oStrictHostKeyChecking=ask") - else: - argv.append("-oStrictHostKeyChecking=yes") - argv.extend(["%s@%s" % (user, hostname), command]) - return utils.RunCmd(argv) - - -def CopyFileToNode(node, filename): - """Copy a file to another node with scp. - - Args: - node: node in the cluster - filename: absolute pathname of a local file - - Returns: - success: True/False + user_dir = utils.GetHomeDir(user) + if not user_dir: + raise errors.OpExecError("Cannot resolve home of user %s" % user) + + ssh_dir = os.path.join(user_dir, ".ssh") + if not os.path.lexists(ssh_dir): + if mkdir: + try: + os.mkdir(ssh_dir, 0700) + except EnvironmentError, err: + raise errors.OpExecError("Can't create .ssh dir for user %s: %s" % + (user, str(err))) + elif not os.path.isdir(ssh_dir): + raise errors.OpExecError("path ~%s/.ssh is not a directory" % user) + + return [os.path.join(ssh_dir, base) + for base in ["id_dsa", "id_dsa.pub", "authorized_keys"]] + + +class SshRunner: + """Wrapper for SSH commands. """ - if not os.path.isfile(filename): - logger.Error("file %s does not exist" % (filename)) - return False + def __init__(self, cluster_name): + self.cluster_name = cluster_name + + def _BuildSshOptions(self, batch, ask_key, use_cluster_key, + strict_host_check): + """Builds a list with needed SSH options. + + @param batch: same as ssh's batch option + @param ask_key: allows ssh to ask for key confirmation; this + parameter conflicts with the batch one + @param use_cluster_key: if True, use the cluster name as the + HostKeyAlias name + @param strict_host_check: this makes the host key checking strict + + @rtype: list + @return: the list of options ready to use in L{utils.RunCmd} + + """ + options = [ + "-oEscapeChar=none", + "-oHashKnownHosts=no", + "-oGlobalKnownHostsFile=%s" % constants.SSH_KNOWN_HOSTS_FILE, + "-oUserKnownHostsFile=/dev/null", + ] - if not os.path.isabs(filename): - logger.Error("file %s must be an absolute path" % (filename)) - return False + if use_cluster_key: + options.append("-oHostKeyAlias=%s" % self.cluster_name) + + # TODO: Too many boolean options, maybe convert them to more descriptive + # constants. - command = ["scp", "-q", "-p", "-oStrictHostKeyChecking=yes", - "-oBatchMode=yes", filename, "%s:%s" % (node, filename)] + # Note: ask_key conflicts with batch mode + if batch: + if ask_key: + raise errors.ProgrammerError("SSH call requested conflicting options") - result = utils.RunCmd(command) + options.append("-oBatchMode=yes") - if result.failed: - logger.Error("copy to node %s failed (%s) error %s," - " command was %s" % - (node, result.fail_reason, result.output, result.cmd)) + if strict_host_check: + options.append("-oStrictHostKeyChecking=yes") + else: + options.append("-oStrictHostKeyChecking=no") - return not result.failed + elif ask_key: + options.extend([ + "-oStrictHostKeyChecking=ask", + ]) + + return options + + def BuildCmd(self, hostname, user, command, batch=True, ask_key=False, + tty=False, use_cluster_key=True, strict_host_check=True): + """Build an ssh command to execute a command on a remote node. + + @param hostname: the target host, string + @param user: user to auth as + @param command: the command + @param batch: if true, ssh will run in batch mode with no prompting + @param ask_key: if true, ssh will run with + StrictHostKeyChecking=ask, so that we can connect to an + unknown host (not valid in batch mode) + @param use_cluster_key: whether to expect and use the + cluster-global SSH key + @param strict_host_check: whether to check the host's SSH key at all + @return: the ssh call to run 'command' on the remote host. -def VerifyNodeHostname(node): - """Verify hostname consistency via SSH. + """ + argv = [constants.SSH, "-q"] + argv.extend(self._BuildSshOptions(batch, ask_key, use_cluster_key, + strict_host_check)) + if tty: + argv.append("-t") + argv.extend(["%s@%s" % (user, hostname), command]) + return argv + def Run(self, *args, **kwargs): + """Runs a command on a remote node. - This functions connects via ssh to a node and compares the hostname - reported by the node to the name with have (the one that we - connected to). + This method has the same return value as `utils.RunCmd()`, which it + uses to launch ssh. - This is used to detect problems in ssh known_hosts files - (conflicting known hosts) and incosistencies between dns/hosts - entries and local machine names + Args: see SshRunner.BuildCmd. - Args: - node: nodename of a host to check. can be short or full qualified hostname + @rtype: L{utils.RunResult} + @return: the result as from L{utils.RunCmd()} - Returns: - (success, detail) - where - success: True/False - detail: String with details + """ + return utils.RunCmd(self.BuildCmd(*args, **kwargs)) - """ - retval = SSHCall(node, 'root', 'hostname') + def CopyFileToNode(self, node, filename): + """Copy a file to another node with scp. + + @param node: node in the cluster + @param filename: absolute pathname of a local file + + @rtype: boolean + @return: the success of the operation + + """ + if not os.path.isabs(filename): + logging.error("File %s must be an absolute path", filename) + return False + + if not os.path.isfile(filename): + logging.error("File %s does not exist", filename) + return False + + command = [constants.SCP, "-q", "-p"] + command.extend(self._BuildSshOptions(True, False, True, True)) + command.append(filename) + command.append("%s:%s" % (node, filename)) + + result = utils.RunCmd(command) - if retval.failed: - msg = "ssh problem" - output = retval.output - if output: - msg += ": %s" % output - return False, msg + if result.failed: + logging.error("Copy to node %s failed (%s) error %s," + " command was %s", + node, result.fail_reason, result.output, result.cmd) - remotehostname = retval.stdout.strip() + return not result.failed - if not remotehostname or remotehostname != node: - return False, "hostname mismatch, got %s" % remotehostname + def VerifyNodeHostname(self, node): + """Verify hostname consistency via SSH. - return True, "host matches" + This functions connects via ssh to a node and compares the hostname + reported by the node to the name with have (the one that we + connected to). + + This is used to detect problems in ssh known_hosts files + (conflicting known hosts) and incosistencies between dns/hosts + entries and local machine names + + @param node: nodename of a host to check; can be short or + full qualified hostname + + @return: (success, detail), where: + - success: True/False + - detail: string with details + + """ + retval = self.Run(node, 'root', 'hostname') + + if retval.failed: + msg = "ssh problem" + output = retval.output + if output: + msg += ": %s" % output + else: + msg += ": %s (no output)" % retval.fail_reason + logging.error("Command %s failed: %s" % (retval.cmd, msg)) + return False, msg + + remotehostname = retval.stdout.strip() + + if not remotehostname or remotehostname != node: + return False, "hostname mismatch, got %s" % remotehostname + + return True, "host matches" + + +def WriteKnownHostsFile(cfg, file_name): + """Writes the cluster-wide equally known_hosts file. + + """ + utils.WriteFile(file_name, mode=0600, + data="%s ssh-rsa %s\n" % (cfg.GetClusterName(), + cfg.GetHostKey()))