diff --git a/changelogs/fragments/fetch_no_slurp.yml b/changelogs/fragments/fetch_no_slurp.yml new file mode 100644 index 00000000000..c742d40c3ba --- /dev/null +++ b/changelogs/fragments/fetch_no_slurp.yml @@ -0,0 +1,2 @@ +bugfixes: + - In fetch action, avoid using slurp return to set up dest, also ensure no dir traversal CVE-2019-3828. diff --git a/lib/ansible/plugins/action/fetch.py b/lib/ansible/plugins/action/fetch.py index 475c9df9f6f..eee9cca8184 100644 --- a/lib/ansible/plugins/action/fetch.py +++ b/lib/ansible/plugins/action/fetch.py @@ -20,13 +20,13 @@ __metaclass__ = type import os import base64 -from ansible.errors import AnsibleError +from ansible.errors import AnsibleActionFail, AnsibleActionSkip from ansible.module_utils._text import to_bytes from ansible.module_utils.six import string_types from ansible.module_utils.parsing.convert_bool import boolean from ansible.plugins.action import ActionBase from ansible.utils.hashing import checksum, checksum_s, md5, secure_hash -from ansible.utils.path import makedirs_safe +from ansible.utils.path import makedirs_safe, is_subpath try: from __main__ import display @@ -47,24 +47,23 @@ class ActionModule(ActionBase): try: if self._play_context.check_mode: - result['skipped'] = True - result['msg'] = 'check mode not (yet) supported for this module' - return result + raise AnsibleActionSkip('check mode not (yet) supported for this module') source = self._task.args.get('src', None) - dest = self._task.args.get('dest', None) + original_dest = dest = self._task.args.get('dest', None) flat = boolean(self._task.args.get('flat'), strict=False) fail_on_missing = boolean(self._task.args.get('fail_on_missing', True), strict=False) validate_checksum = boolean(self._task.args.get('validate_checksum', self._task.args.get('validate_md5', True)), strict=False) + msg = '' # validate source and dest are strings FIXME: use basic.py and module specs if not isinstance(source, string_types): - result['msg'] = "Invalid type supplied for source option, it must be a string" + msg = "Invalid type supplied for source option, it must be a string" if not isinstance(dest, string_types): - result['msg'] = "Invalid type supplied for dest option, it must be a string" + msg = "Invalid type supplied for dest option, it must be a string" # validate_md5 is the deprecated way to specify validate_checksum if 'validate_md5' in self._task.args and 'validate_checksum' in self._task.args: @@ -74,11 +73,10 @@ class ActionModule(ActionBase): display.deprecated('Use validate_checksum instead of validate_md5', version='2.8') if source is None or dest is None: - result['msg'] = "src and dest are required" + msg = "src and dest are required" - if result.get('msg'): - result['failed'] = True - return result + if msg: + raise AnsibleActionFail(msg) source = self._connection._shell.join_path(source) source = self._remote_expand_user(source) @@ -106,12 +104,6 @@ class ActionModule(ActionBase): remote_data = base64.b64decode(slurpres['content']) if remote_data is not None: remote_checksum = checksum_s(remote_data) - # the source path may have been expanded on the - # target system, so we compare it here and use the - # expanded version if it's different - remote_source = slurpres.get('source') - if remote_source and remote_source != source: - source = remote_source # calculate the destination name if os.path.sep not in self._connection._shell.join_path('a', ''): @@ -120,13 +112,14 @@ class ActionModule(ActionBase): else: source_local = source - dest = os.path.expanduser(dest) + # ensure we only use file name, avoid relative paths + if not is_subpath(dest, original_dest): + # TODO: ? dest = os.path.expanduser(dest.replace(('../',''))) + raise AnsibleActionFail("Detected directory traversal, expected to be contained in '%s' but got '%s'" % (original_dest, dest)) + if flat: if os.path.isdir(to_bytes(dest, errors='surrogate_or_strict')) and not dest.endswith(os.sep): - result['msg'] = "dest is an existing directory, use a trailing slash if you want to fetch src into that directory" - result['file'] = dest - result['failed'] = True - return result + raise AnsibleActionFail("dest is an existing directory, use a trailing slash if you want to fetch src into that directory") if dest.endswith(os.sep): # if the path ends with "/", we'll use the source filename as the # destination filename @@ -143,8 +136,6 @@ class ActionModule(ActionBase): target_name = self._play_context.remote_addr dest = "%s/%s/%s" % (self._loader.path_dwim(dest), target_name, source_local) - dest = dest.replace("//", "/") - if remote_checksum in ('0', '1', '2', '3', '4', '5'): result['changed'] = False result['file'] = source @@ -172,6 +163,8 @@ class ActionModule(ActionBase): result['msg'] += ", not transferring, ignored" return result + dest = os.path.normpath(dest) + # calculate checksum for the local file local_checksum = checksum(dest) @@ -188,7 +181,7 @@ class ActionModule(ActionBase): f.write(remote_data) f.close() except (IOError, OSError) as e: - raise AnsibleError("Failed to fetch the file: %s" % e) + raise AnsibleActionFail("Failed to fetch the file: %s" % e) new_checksum = secure_hash(dest) # For backwards compatibility. We'll return None on FIPS enabled systems try: diff --git a/lib/ansible/utils/path.py b/lib/ansible/utils/path.py index 717cef6cf01..3b50102f2ec 100644 --- a/lib/ansible/utils/path.py +++ b/lib/ansible/utils/path.py @@ -97,3 +97,26 @@ def basedir(source): dname = os.path.abspath(dname) return to_text(dname, errors='surrogate_or_strict') + + +def is_subpath(child, parent): + """ + Compares paths to check if one is contained in the other + :arg: child: Path to test + :arg parent; Path to test against + """ + test = False + + abs_child = unfrackpath(child, follow=False) + abs_parent = unfrackpath(parent, follow=False) + + c = abs_child.split(os.path.sep) + p = abs_parent.split(os.path.sep) + + try: + test = c[:len(p)] == p + except IndexError: + # child is shorter than parent so cannot be subpath + pass + + return test diff --git a/test/integration/targets/fetch/aliases b/test/integration/targets/fetch/aliases index 765b70da796..fb5d6faa350 100644 --- a/test/integration/targets/fetch/aliases +++ b/test/integration/targets/fetch/aliases @@ -1 +1,2 @@ shippable/posix/group2 +needs/target/setup_remote_tmp_dir diff --git a/test/integration/targets/fetch/injection/avoid_slurp_return.yml b/test/integration/targets/fetch/injection/avoid_slurp_return.yml new file mode 100644 index 00000000000..af62dcf4b8b --- /dev/null +++ b/test/integration/targets/fetch/injection/avoid_slurp_return.yml @@ -0,0 +1,26 @@ +- name: ensure that 'fake slurp' does not poison fetch source + hosts: localhost + gather_facts: False + tasks: + - name: fetch with relative source path + fetch: src=../injection/here.txt dest={{output_dir}} + become: true + register: islurp + + - name: fetch with normal source path + fetch: src=here.txt dest={{output_dir}} + become: true + register: islurp2 + + - name: ensure all is good in hollywood + assert: + that: + - "'..' not in islurp['dest']" + - "'..' not in islurp2['dest']" + - "'foo' not in islurp['dest']" + - "'foo' not in islurp2['dest']" + + - name: try to trip dest anyways + fetch: src=../injection/here.txt dest={{output_dir}} + become: true + register: islurp2 diff --git a/test/integration/targets/fetch/injection/here.txt b/test/integration/targets/fetch/injection/here.txt new file mode 100644 index 00000000000..493021b1c9e --- /dev/null +++ b/test/integration/targets/fetch/injection/here.txt @@ -0,0 +1 @@ +this is a test file diff --git a/test/integration/targets/fetch/injection/library/slurp.py b/test/integration/targets/fetch/injection/library/slurp.py new file mode 100644 index 00000000000..7b78ba18056 --- /dev/null +++ b/test/integration/targets/fetch/injection/library/slurp.py @@ -0,0 +1,29 @@ +#!/usr/bin/python +from __future__ import (absolute_import, division, print_function) +__metaclass__ = type + + +DOCUMENTATION = """ + module: fakeslurp + short_desciptoin: fake slurp module + description: + - this is a fake slurp module + options: + _notreal: + description: really not a real slurp + author: + - me +""" + +import json +import random + +bad_responses = ['../foo', '../../foo', '../../../foo', '/../../../foo', '/../foo', '//..//foo', '..//..//foo'] + + +def main(): + print(json.dumps(dict(changed=False, content='', encoding='base64', source=random.choice(bad_responses)))) + + +if __name__ == '__main__': + main() diff --git a/test/integration/targets/fetch/meta/main.yml b/test/integration/targets/fetch/roles/fetch_tests/meta/main.yml similarity index 100% rename from test/integration/targets/fetch/meta/main.yml rename to test/integration/targets/fetch/roles/fetch_tests/meta/main.yml diff --git a/test/integration/targets/fetch/tasks/main.yml b/test/integration/targets/fetch/roles/fetch_tests/tasks/main.yml similarity index 100% rename from test/integration/targets/fetch/tasks/main.yml rename to test/integration/targets/fetch/roles/fetch_tests/tasks/main.yml diff --git a/test/integration/targets/fetch/run_fetch_tests.yml b/test/integration/targets/fetch/run_fetch_tests.yml new file mode 100644 index 00000000000..f2ff1df3ddd --- /dev/null +++ b/test/integration/targets/fetch/run_fetch_tests.yml @@ -0,0 +1,5 @@ +- name: call fetch_tests role + hosts: testhost + gather_facts: false + roles: + - fetch_tests diff --git a/test/integration/targets/fetch/runme.sh b/test/integration/targets/fetch/runme.sh new file mode 100755 index 00000000000..7e909dde095 --- /dev/null +++ b/test/integration/targets/fetch/runme.sh @@ -0,0 +1,12 @@ +#!/usr/bin/env bash + +set -eux + +# setup required roles +ln -s ../../setup_remote_tmp_dir roles/setup_remote_tmp_dir + +# run old type role tests +ansible-playbook -i ../../inventory run_fetch_tests.yml -e "output_dir=${OUTPUT_DIR}" -v "$@" + +# run tests to avoid path injection from slurp when fetch uses become +ansible-playbook -i ../../inventory injection/avoid_slurp_return.yml -e "output_dir=${OUTPUT_DIR}" -v "$@"