From 4259fde22f61ce4a6b66d8aabb825483be3c7f84 Mon Sep 17 00:00:00 2001 From: Slawek Kaplonski Date: Mon, 23 Aug 2021 13:01:37 +0200 Subject: [PATCH] Remove dhcp_extra_opt value after first newline character Passing newline to the dnsmasq may cause security issues, especially that in case of Neutron that dhcp options' values are controlled by cloud users. This patch removes everything what is after first newline character in the dhcp_extra_opt's values before passing them to dnsmasq. Closes-Bug: #1939733 Change-Id: Ifeaf258f0b5ea86f25620ac4116d618980a7272e --- neutron/agent/linux/dhcp.py | 7 ++++--- neutron/tests/unit/agent/linux/test_dhcp.py | 7 ++++++- ...wline-chars-in-dhcp-extra-options-bf86d30371556d63.yaml | 6 ++++++ 3 files changed, 16 insertions(+), 4 deletions(-) create mode 100644 releasenotes/notes/fix-newline-chars-in-dhcp-extra-options-bf86d30371556d63.yaml diff --git a/neutron/agent/linux/dhcp.py b/neutron/agent/linux/dhcp.py index dd8f317525..8e247adb24 100644 --- a/neutron/agent/linux/dhcp.py +++ b/neutron/agent/linux/dhcp.py @@ -1322,10 +1322,11 @@ class Dnsmasq(DhcpLocalProcess): elif not option.isdigit(): option = 'option:%s' % option if extra_tag: - tags = ('tag:' + tag, extra_tag[:-1], '%s' % option) + tags = ['tag:' + tag, extra_tag[:-1], '%s' % option] else: - tags = ('tag:' + tag, '%s' % option) - return ','.join(tags + args) + tags = ['tag:' + tag, '%s' % option] + + return ','.join(tags + [v.split("\n", 1)[0] for v in args]) @staticmethod def _convert_to_literal_addrs(ip_version, ips): diff --git a/neutron/tests/unit/agent/linux/test_dhcp.py b/neutron/tests/unit/agent/linux/test_dhcp.py index f90aaff1a6..cc02eb22cf 100644 --- a/neutron/tests/unit/agent/linux/test_dhcp.py +++ b/neutron/tests/unit/agent/linux/test_dhcp.py @@ -230,6 +230,9 @@ class FakeV6PortExtraOpt(object): self.extra_dhcp_opts = [ DhcpOpt(opt_name='dns-server', opt_value='ffea:3ba5:a17a:4ba3::100', + ip_version=constants.IP_VERSION_6), + DhcpOpt(opt_name='malicious-option', + opt_value='aaa\nbbb.ccc\n', ip_version=constants.IP_VERSION_6)] @@ -2909,7 +2912,9 @@ class TestDnsmasq(TestBase): exp_opt_data = ('tag:subnet-eeeeeeee-eeee-eeee-eeee-eeeeeeeeeeee,' 'option6:domain-search,openstacklocal\n' 'tag:port-hhhhhhhh-hhhh-hhhh-hhhh-hhhhhhhhhhhh,' - 'option6:dns-server,ffea:3ba5:a17a:4ba3::100').lstrip() + 'option6:dns-server,ffea:3ba5:a17a:4ba3::100\n' + 'tag:port-hhhhhhhh-hhhh-hhhh-hhhh-hhhhhhhhhhhh,' + 'option6:malicious-option,aaa').lstrip() dm = self._get_dnsmasq(FakeV6NetworkStatelessDHCP()) dm._output_hosts_file() dm._output_opts_file() diff --git a/releasenotes/notes/fix-newline-chars-in-dhcp-extra-options-bf86d30371556d63.yaml b/releasenotes/notes/fix-newline-chars-in-dhcp-extra-options-bf86d30371556d63.yaml new file mode 100644 index 0000000000..d2a8c2f68b --- /dev/null +++ b/releasenotes/notes/fix-newline-chars-in-dhcp-extra-options-bf86d30371556d63.yaml @@ -0,0 +1,6 @@ +--- +security: + - | + Fix `bug 1939733 `_ by + dropping from the dhcp extra option values everything what is after first + newline (``\n``) character before passing them to the dnsmasq. -- 2.33.0