Source code for plainbox.impl.ctrl

# This file is part of Checkbox.
#
# Copyright 2013 Canonical Ltd.
# Written by:
#   Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
#
# Checkbox is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 3,
# as published by the Free Software Foundation.

#
# Checkbox is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Checkbox.  If not, see <http://www.gnu.org/licenses/>.

"""
:mod:`plainbox.impl.ctrl` -- Controller Classes
===============================================

Session controller classes implement the glue between models (jobs, whitelists,
session state) and the rest of the application. They encapsulate knowledge that
used to be special-cased and sprinkled around various parts of both plainbox
and particular plainbox-using applications.

Execution controllers are used by the :class:`~plainbox.impl.runner.JobRunner`
class to select the best method to execute a command of a particular job.  This
is mostly applicable to jobs that need to run as another user, typically as
root, as the method that is used to effectively gain root differs depending on
circumstances.
"""

import abc
import contextlib
import grp
import itertools
import logging
import os
import posix
import tempfile
from subprocess import check_output, CalledProcessError, STDOUT

from plainbox.abc import IExecutionController
from plainbox.abc import IJobResult
from plainbox.abc import ISessionStateController
from plainbox.i18n import gettext as _
from plainbox.impl.depmgr import DependencyDuplicateError
from plainbox.impl.depmgr import DependencyMissingError
from plainbox.impl.job import JobDefinition
from plainbox.impl.job import JobOutputTextSource
from plainbox.impl.resource import ExpressionCannotEvaluateError
from plainbox.impl.resource import ExpressionFailedError
from plainbox.impl.resource import Resource
from plainbox.impl.secure.config import Unset
from plainbox.impl.secure.providers.v1 import Provider1
from plainbox.impl.secure.rfc822 import RFC822SyntaxError
from plainbox.impl.secure.rfc822 import gen_rfc822_records
from plainbox.impl.session.jobs import JobReadinessInhibitor

__all__ = [
    'CheckBoxSessionStateController',
    'RootViaPTL1ExecutionController',
    'RootViaPkexecExecutionController',
    'RootViaSudoExecutionController',
    'UserJobExecutionController',
    'checkbox_session_state_ctrl',
]


logger = logging.getLogger("plainbox.ctrl")


[docs]class CheckBoxSessionStateController(ISessionStateController): """ A combo controller for CheckBox-like jobs. This controller implements the following features: * A job may depend on another job, this is expressed via the 'depends' attribute. Cyclic dependencies are not allowed. A job will become inhibited if any of its dependencies have outcome other than OUTCOME_PASS * A job may require that a particular resource expression evaluates to true. This is expressed via the 'requires' attribute. A job will become inhibited if any of the requirement programs evaluates to value other than True. * A job may have the attribute 'plugin' equal to "local" which will cause the controller to interpret the stdout of the command as a set of job definitions. * A job may have the attribute 'plugin' equal to "resource" which will cause the controller to interpret the stdout of the command as a set of resource definitions. """
[docs] def get_dependency_set(self, job): """ Get the set of direct dependencies of a particular job. :param job: A IJobDefinition instance that is to be visited :returns: set of pairs (dep_type, job_id) Returns a set of pairs (dep_type, job_id) that describe all dependencies of the specified job. The first element in the pair, dep_type, is either DEP_TYPE_DIRECT or DEP_TYPE_RESOURCE. The second element is the id of the job. """ direct = DependencyMissingError.DEP_TYPE_DIRECT resource = DependencyMissingError.DEP_TYPE_RESOURCE return set(itertools.chain( zip(itertools.repeat(direct), job.get_direct_dependencies()), zip(itertools.repeat(resource), job.get_resource_dependencies())))
[docs] def get_inhibitor_list(self, session_state, job): """ Get a list of readiness inhibitors that inhibit a particular job. :param session_state: A SessionState instance that is used to interrogate the state of the session where it matters for a particular job. Currently this is used to access resources and job results. :param job: A JobDefinition instance :returns: List of JobReadinessInhibitor """ # Check if all job resource requirements are met prog = job.get_resource_program() inhibitors = [] if prog is not None: try: prog.evaluate_or_raise(session_state.resource_map) except ExpressionCannotEvaluateError as exc: # Lookup the related job (the job that provides the # resources needed by the expression that cannot be # evaluated) related_job = session_state.job_state_map[ exc.expression.resource_id].job # Add A PENDING_RESOURCE inhibitor as we are unable to # determine if the resource requirement is met or not. This # can happen if the resource job did not ran for any reason # (it can either be prevented from running by normal means # or simply be on the run_list but just was not executed # yet). inhibitor = JobReadinessInhibitor( cause=JobReadinessInhibitor.PENDING_RESOURCE, related_job=related_job, related_expression=exc.expression) inhibitors.append(inhibitor) except ExpressionFailedError as exc: # Lookup the related job (the job that provides the # resources needed by the expression that failed) related_job = session_state.job_state_map[ exc.expression.resource_id].job # Add a FAILED_RESOURCE inhibitor as we have all the data # to run the requirement program but it simply returns a # non-True value. This typically indicates a missing # software package or necessary hardware. inhibitor = JobReadinessInhibitor( cause=JobReadinessInhibitor.FAILED_RESOURCE, related_job=related_job, related_expression=exc.expression) inhibitors.append(inhibitor) # Check if all job dependencies ran successfully for dep_id in sorted(job.get_direct_dependencies()): dep_job_state = session_state.job_state_map[dep_id] # If the dependency did not have a chance to run yet add the # PENDING_DEP inhibitor. if dep_job_state.result.outcome == IJobResult.OUTCOME_NONE: inhibitor = JobReadinessInhibitor( cause=JobReadinessInhibitor.PENDING_DEP, related_job=dep_job_state.job) inhibitors.append(inhibitor) # If the dependency is anything but successful add the # FAILED_DEP inhibitor. In theory the PENDING_DEP code above # could be discarded but this would loose context and would # prevent the operator from actually understanding why a job # cannot run. elif dep_job_state.result.outcome != IJobResult.OUTCOME_PASS: inhibitor = JobReadinessInhibitor( cause=JobReadinessInhibitor.FAILED_DEP, related_job=dep_job_state.job) inhibitors.append(inhibitor) return inhibitors
[docs] def observe_result(self, session_state, job, result): """ Notice the specified test result and update readiness state. :param session_state: A SessionState object :param job: A JobDefinition object :param result: A IJobResult object This function updates the internal result collection with the data from the specified test result. Results can safely override older results. Results also change the ready map (jobs that can run) because of dependency relations. Some results have deeper meaning, those are results for local and resource jobs. They are discussed in detail below: Resource jobs produce resource records which are used as data to run requirement expressions against. Each time a result for a resource job is presented to the session it will be parsed as a collection of RFC822 records. A new entry is created in the resource map (entirely replacing any old entries), with a list of the resources that were parsed from the IO log. Local jobs produce more jobs. Like with resource jobs, their IO log is parsed and interpreted as additional jobs. Unlike in resource jobs local jobs don't replace anything. They cannot replace an existing job with the same id. """ # Store the result in job_state_map session_state.job_state_map[job.id].result = result session_state.on_job_state_map_changed() session_state.on_job_result_changed(job, result) # Treat some jobs specially and interpret their output if job.plugin == "resource": self._process_resource_result(session_state, job, result) elif job.plugin == "local": self._process_local_result(session_state, job, result)
def _process_resource_result(self, session_state, job, result): """ Analyze a result of a CheckBox "resource" job and generate or replace resource records. """ new_resource_list = [] for record in gen_rfc822_records_from_io_log(job, result): # XXX: Consider forwarding the origin object here. I guess we # should have from_frc822_record as with JobDefinition resource = Resource(record.data) logger.info( _("Storing resource record %r: %s"), job.id, resource) new_resource_list.append(resource) # Replace any old resources with the new resource list session_state.set_resource_list(job.id, new_resource_list) def _process_local_result(self, session_state, job, result): """ Analyze a result of a CheckBox "local" job and generate additional job definitions """ # First parse all records and create a list of new jobs (confusing # name, not a new list of jobs) new_job_list = [] for record in gen_rfc822_records_from_io_log(job, result): new_job = job.create_child_job_from_record(record) new_job_list.append(new_job) # Then for each new job, add it to the job_list, unless it collides # with another job with the same id. for new_job in new_job_list: try: added_job = session_state.add_job(new_job, recompute=False) except DependencyDuplicateError as exc: # XXX: there should be a channel where such errors could be # reported back to the UI layer. Perhaps update_job_result() # could simply return a list of problems in a similar manner # how update_desired_job_list() does. logger.warning( # TRANSLATORS: keep the word "local" untranslated. It is a # special type of job that needs to be distinguished. _("Local job %s produced job %r that collides with" " an existing job %s (from %s), the new job was" " discarded"), job, exc.duplicate_job, exc.job, exc.job.origin) else: # Patch the origin of the existing job so that it traces # back to the job that "generated" it again. This is # basically required to get __category__ jobs to associate # themselves with their children. if added_job is not new_job: added_job.update_origin(new_job.origin)
def gen_rfc822_records_from_io_log(job, result): """ Convert io_log from a job result to a sequence of rfc822 records """ logger.debug(_("processing output from a job: %r"), job) # Select all stdout lines from the io log line_gen = (record[2].decode('UTF-8', errors='replace') for record in result.get_io_log() if record[1] == 'stdout') # Allow the generated records to be traced back to the job that defined # the command which produced (printed) them. source = JobOutputTextSource(job) try: # Parse rfc822 records from the subsequent lines for record in gen_rfc822_records(line_gen, source=source): yield record except RFC822SyntaxError as exc: # When this exception happens we will _still_ store all the # preceding records. This is worth testing logger.warning( # TRANSLATORS: keep the word "local" untranslated. It is a # special type of job that needs to be distinguished. _("local script %s returned invalid RFC822 data: %s"), job, exc) checkbox_session_state_ctrl = CheckBoxSessionStateController() class SymLinkNest: """ A class for setting up a control directory with symlinked executables """ def __init__(self, dirname): self._dirname = dirname def add_provider(self, provider): """ Add all of the executables associated a particular provider :param provider: A Provider1 instance """ for filename in provider.get_all_executables(): self.add_executable(filename) def add_executable(self, filename): """ Add a executable to the control directory """ logger.debug( _("Adding executable %s to nest %s"), filename, self._dirname) os.symlink( filename, os.path.join( self._dirname, os.path.basename(filename))) class CheckBoxExecutionController(IExecutionController): """ Base class for checkbox-like execution controllers. This abstract class provides common features for all checkbox execution controllers. """ def __init__(self, session_dir, provider_list): """ Initialize a new CheckBoxExecutionController :param session_dir: Base directory of the session this job will execute in. This directory is used to co-locate some data that is unique to this execution as well as data that is shared by all executions. :param provider_list: A list of Provider1 objects that will be available for script dependency resolutions. Currently all of the scripts are makedirs available but this will be refined to the minimal set later. """ self._session_dir = session_dir self._provider_list = provider_list def execute_job(self, job, config, extcmd_popen): """ Execute the specified job using the specified subprocess-like object :param job: The JobDefinition to execute :param config: A PlainBoxConfig instance which can be used to load missing environment definitions that apply to all jobs. It is used to provide values for missing environment variables that are required by the job (as expressed by the environ key in the job definition file). :param extcmd_popen: A subprocess.Popen like object :returns: The return code of the command, as returned by subprocess.call() """ # CHECKBOX_DATA is where jobs can share output. # It has to be an directory that scripts can assume exists. if not os.path.isdir(self.CHECKBOX_DATA): os.makedirs(self.CHECKBOX_DATA) # Setup the executable nest directory with self.configured_filesystem(job, config) as nest_dir: # Get the command and the environment. # of this execution controller cmd = self.get_execution_command(job, config, nest_dir) env = self.get_execution_environment(job, config, nest_dir) # run the command logger.debug(_("job[%s] executing %r with env %r"), job.id, cmd, env) return extcmd_popen.call(cmd, env=env) @contextlib.contextmanager def configured_filesystem(self, job, config): """ Context manager for handling filesystem aspects of job execution. :param job: The JobDefinition to execute :param config: A PlainBoxConfig instance which can be used to load missing environment definitions that apply to all jobs. It is used to provide values for missing environment variables that are required by the job (as expressed by the environ key in the job definition file). :returns: Pathname of the executable symlink nest directory. """ # Create a nest for all the private executables needed for execution prefix = 'nest-' suffix = '.{}'.format(job.checksum) with tempfile.TemporaryDirectory(suffix, prefix) as nest_dir: logger.debug(_("Symlink nest for executables: %s"), nest_dir) nest = SymLinkNest(nest_dir) # Add all providers sharing namespace with the current job to PATH for provider in self._provider_list: if job.provider.namespace == provider.namespace: nest.add_provider(provider) logger.debug(_("Symlink nest for executables: %s"), nest_dir) yield nest_dir def get_score(self, job): """ Compute how applicable this controller is for the specified job. :returns: A numeric score, or None if the controller cannot run this job. The higher the value, the more applicable this controller is. """ if isinstance(job, JobDefinition): return self.get_checkbox_score(job) else: return -1 @abc.abstractmethod def get_checkbox_score(self, job): """ Compute how applicable this controller is for the specified job. The twist is that it is always a checkbox job definition so we can be more precise. :returns: A number that specifies how applicable this controller is for the specified job (the higher the better) or None if it cannot be used at all """ @abc.abstractmethod def get_execution_command(self, job, config, nest_dir): """ Get the command to execute the specified job :param job: job definition with the command and environment definitions :param config: A PlainBoxConfig instance which can be used to load missing environment definitions that apply to all jobs. It is used to provide values for missing environment variables that are required by the job (as expressed by the environ key in the job definition file). :param nest_dir: A directory with a nest of symlinks to all executables required to execute the specified job. This argument may or may not be used, depending on how PATH is passed to the command (via environment or via the commant line) :returns: List of command arguments """ def get_execution_environment(self, job, config, nest_dir): """ Get the environment required to execute the specified job: :param job: job definition with the command and environment definitions :param config: A PlainBoxConfig instance which can be used to load missing environment definitions that apply to all jobs. It is used to provide values for missing environment variables that are required by the job (as expressed by the environ key in the job definition file). :param nest_dir: A directory with a nest of symlinks to all executables required to execute the specified job. This argument may or may not be used, depending on how PATH is passed to the command (via environment or via the commant line) :return: dictionary with the environment to use. This returned environment has additional PATH, PYTHONPATH entries. It also uses fixed LANG so that scripts behave as expected. Lastly it sets CHECKBOX_SHARE and CHECKBOX_DATA that may be required by some scripts. """ # Get a proper environment env = dict(os.environ) # Use non-internationalized environment env['LANG'] = 'C.UTF-8' if 'LANGUAGE' in env: del env['LANGUAGE'] for name in list(env.keys()): if name.startswith("LC_"): del env[name] # Use PATH that can lookup checkbox scripts if job.provider.extra_PYTHONPATH: env['PYTHONPATH'] = os.pathsep.join( [job.provider.extra_PYTHONPATH] + env.get("PYTHONPATH", "").split(os.pathsep)) # Inject nest_dir into PATH env['PATH'] = os.pathsep.join( [nest_dir] + env.get("PATH", "").split(os.pathsep)) # Add CHECKBOX_SHARE that is needed by one script if job.provider.CHECKBOX_SHARE is not None: env['CHECKBOX_SHARE'] = job.provider.CHECKBOX_SHARE # Add CHECKBOX_DATA (temporary checkbox data) env['CHECKBOX_DATA'] = self.CHECKBOX_DATA # Add plainbox equivalents of the two above if job.provider.data_dir is not None: env['PLAINBOX_PROVIDER_DATA'] = job.provider.data_dir env['PLAINBOX_SESSION_SHARE'] = self.CHECKBOX_DATA # Inject additional variables that are requested in the config if config is not None and config.environment is not Unset: for env_var in config.environment: # Don't override anything that is already present in the # current environment. This will allow users to customize # variables without editing any config files. if env_var in env: continue # If the environment section of the configuration file has a # particular variable then copy it over. env[env_var] = config.environment[env_var] return env @property def CHECKBOX_DATA(self): """ value of the CHECKBOX_DATA environment variable. This variable names a sub-directory of the session directory where jobs can share data between invocations. """ return os.path.join(self._session_dir, "CHECKBOX_DATA")
[docs]class UserJobExecutionController(CheckBoxExecutionController): """ An execution controller that works for jobs invoked as the current user. """
[docs] def get_execution_command(self, job, config, nest_dir): """ Get the command to execute the specified job :param job: job definition with the command and environment definitions :param config: A PlainBoxConfig instance which can be used to load missing environment definitions that apply to all jobs. Ignored. :param nest_dir: A directory with a nest of symlinks to all executables required to execute the specified job. Ingored. :returns: List of command arguments This basically returns ['bash', '-c', job.command] """ return ['bash', '-c', job.command]
[docs] def get_checkbox_score(self, job): """ Compute how applicable this controller is for the specified job. :returns: 1 for jobs without a user override, 3 for jobs with user override if the invoking uid is 0 (root), -1 otherwise """ if job.user is None: return 1 if os.getuid() == 0: return 4 else: return -1
class CheckBoxDifferentialExecutionController(CheckBoxExecutionController): """ A CheckBoxExecutionController subclass that uses differential environment. This special subclass has a special :meth:`get_execution_environment()` method that always returns None. Instead the new method :meth:`get_differential_execution_environment()` that returns the difference between the target environment and the current environment. """ def get_differential_execution_environment(self, job, config, nest_dir): """ Get the environment required to execute the specified job: :param job: job definition with the command and environment definitions :param config: A PlainBoxConfig instance which can be used to load missing environment definitions that apply to all jobs. It is used to provide values for missing environment variables that are required by the job (as expressed by the environ key in the job definition file). :param nest_dir: A directory with a nest of symlinks to all executables required to execute the specified job. This is simply passed to :meth:`get_execution_environment()` directly. :returns: Differential environment (see below). This implementation computes the desired environment (as it was computed in the base class) and then discards all of the environment variables that are identical in both sets. The exception are variables that are mentioned in :meth:`plainbox.impl.job.JobDefinition.get_environ_settings()` which are always retained. """ base_env = os.environ target_env = super().get_execution_environment(job, config, nest_dir) return { key: value for key, value in target_env.items() if key not in base_env or base_env[key] != value or key in job.get_environ_settings() } def get_execution_environment(self, job, config, nest_dir): """ Get the environment required to execute the specified job: :param job: job definition with the command and environment definitions. Ignored. :param config: A PlainBoxConfig instance which can be used to load missing environment definitions that apply to all jobs. Ignored. :param nest_dir: A directory with a nest of symlinks to all executables required to execute the specified job. Ignored. :returns: None This implementation always returns None since the environment is always passed in via :meth:`get_execution_command()` """ return None
[docs]class RootViaPTL1ExecutionController(CheckBoxDifferentialExecutionController): """ Execution controller that gains root using plainbox-trusted-launcher-1 """ def __init__(self, session_dir, provider_list): """ Initialize a new RootViaPTL1ExecutionController """ super().__init__(session_dir, provider_list) # Ask pkaction(1) if the "run-plainbox-job" policykit action is # registered on this machine. action_id = b"org.freedesktop.policykit.pkexec.run-plainbox-job" # Catch CalledProcessError because pkaction (polkit < 0.110) always # exits with status 1, see: # https://bugs.freedesktop.org/show_bug.cgi?id=29936#attach_78263 try: result = check_output(["pkaction", "--action-id", action_id], stderr=STDOUT) except CalledProcessError as exc: result = exc.output self.is_supported = True if result.strip() == action_id else False
[docs] def get_execution_command(self, job, config, nest_dir): """ Get the command to invoke. :param job: job definition with the command and environment definitions :param config: A PlainBoxConfig instance which can be used to load missing environment definitions that apply to all jobs. Passed to :meth:`get_differential_execution_environment()`. :param nest_dir: A directory with a nest of symlinks to all executables required to execute the specified job. Passed to :meth:`get_differential_execution_environment()`. This overridden implementation returns especially crafted command that uses pkexec to run the plainbox-trusted-launcher-1 as the desired user (typically root). It passes the checksum of the job definition as argument, along with all of the required environment key-value pairs. If a job is generated it also passes the special via attribute to let the trusted launcher discover the generated job. Currently it supports at most one-level of generated jobs. """ # Run plainbox-trusted-launcher-1 as the required user cmd = ['pkexec', '--user', job.user, 'plainbox-trusted-launcher-1'] # Pass a special switch when working from source if job.provider.name == '2013.com.canonical:checkbox-src': cmd += ['--development'] # Run the specified generator job in the specified environment if job.via is not None: cmd += ['--generator', job.via] parent_env = self.get_differential_execution_environment( job.origin.source.job, config, nest_dir) for key, value in sorted(parent_env.items()): cmd += ['-G', '{}={}'.format(key, value)] # Run the specified target job in the specified environment cmd += ['--target', job.checksum] env = self.get_differential_execution_environment( job, config, nest_dir) for key, value in sorted(env.items()): cmd += ['-T', '{}={}'.format(key, value)] return cmd
[docs] def get_checkbox_score(self, job): """ Compute how applicable this controller is for the specified job. :returns: two for jobs with an user override that can be invoked by the trusted launcher, zero for jobs without an user override that can be invoked by the trusted launcher, -1 otherwise """ # Only works with jobs coming from the Provider1 instance if not isinstance(job.provider, Provider1): return -1 # Be very appropriate for running jobs in the source provider if (os.getenv('PLAINBOX_USE_TRUSTED_LAUNCHER') and job.user is not None and job.provider.name == '2013.com.canonical:checkbox-src'): return 100 # Only works with jobs loaded from the secure PROVIDERPATH if not job.provider.secure: return -1 # Only makes sense with jobs that need to run as another user # Promote this controller only if the trusted launcher is authorized to # run jobs as another user if job.user is not None and self.is_supported: return 3 else: return 0
[docs]class RootViaPkexecExecutionController( CheckBoxDifferentialExecutionController): """ Execution controller that gains root by using pkexec. This controller should be used for jobs that need root but cannot be executed by the plainbox-trusted-launcher-1. This happens whenever the job is not in the system-wide provider location. In practice it is used when working with the special 'checkbox-in-source-tree' provider as well as for jobs that need to run as root from the non-system-wide location. """
[docs] def get_execution_command(self, job, config, nest_dir): """ Get the command to invoke. :param job: job definition with the command and environment definitions :param config: A PlainBoxConfig instance which can be used to load missing environment definitions that apply to all jobs. Passed to :meth:`get_differential_execution_environment()`. :param nest_dir: A directory with a nest of symlinks to all executables required to execute the specified job. Passed to :meth:`get_differential_execution_environment()`. Since we cannot pass environment in the ordinary way while using pkexec(1) (pkexec starts new processes in a sanitized, pristine, environment) we're relying on env(1) to pass some of the environment variables that we require. """ # Run env(1) as the required user cmd = ['pkexec', '--user', job.user, 'env'] # Append all environment data env = self.get_differential_execution_environment( job, config, nest_dir) cmd += ["{key}={value}".format(key=key, value=value) for key, value in sorted(env.items())] # Lastly use bash -c, to run our command cmd += ['bash', '-c', job.command] return cmd
[docs] def get_checkbox_score(self, job): """ Compute how applicable this controller is for the specified job. :returns: one for jobs with a user override, zero otherwise """ if job.user is not None: return 1 else: return 0
[docs]class RootViaSudoExecutionController( CheckBoxDifferentialExecutionController): """ Execution controller that gains root by using sudo. This controller should be used for jobs that need root but cannot be executed by the plainbox-trusted-launcher-1. This happens whenever the job is not in the system-wide provider location. In practice it is used when working with the special 'checkbox-in-source-tree' provider as well as for jobs that need to run as root from the non-system-wide location. Using this controller is preferable to pkexec if running on command line as unlike pkexec, it retains 'memory' and doesn't ask for the password over and over again. """ def __init__(self, session_dir, provider_list): """ Initialize a new RootViaSudoExecutionController :param session_dir: Base directory of the session this job will execute in. This directory is used to co-locate some data that is unique to this execution as well as data that is shared by all executions. """ super().__init__(session_dir, provider_list) # Check if the user can use 'sudo' on this machine. This check is a bit # Ubuntu specific and can be wrong due to local configuration but # without a better API all we can do is guess. # # Shamelessly stolen from command-not-found try: in_sudo_group = grp.getgrnam("sudo").gr_gid in posix.getgroups() except KeyError: in_sudo_group = False try: in_admin_group = grp.getgrnam("admin").gr_gid in posix.getgroups() except KeyError: in_admin_group = False self.user_can_sudo = in_sudo_group or in_admin_group
[docs] def get_execution_command(self, job, config, nest_dir): """ Get the command to invoke. :param job: job definition with the command and environment definitions :param config: A PlainBoxConfig instance which can be used to load missing environment definitions that apply to all jobs. Ignored. :param nest_dir: A directory with a nest of symlinks to all executables required to execute the specified job. Ingored. Since we cannot pass environment in the ordinary way while using sudo(8) (even passing -E doesn't get us everything due to security features built into sudo itself) we're relying on env(1) to pass some of the environment variables that we require. """ # Run env(1) as the required user cmd = ['sudo', '-u', job.user, 'env'] # Append all environment data env = self.get_differential_execution_environment( job, config, nest_dir) cmd += ["{key}={value}".format(key=key, value=value) for key, value in sorted(env.items())] # Lastly use bash -c, to run our command cmd += ['bash', '-c', job.command] return cmd
[docs] def get_checkbox_score(self, job): """ Compute how applicable this controller is for the specified job. :returns: -1 if the job does not have a user override or the user cannot use sudo and 2 otherwise """ # Only makes sense with jobs that need to run as another user if job.user is not None and self.user_can_sudo: return 2 else: return -1