From 441d3eb6d1be940a67ce45a286602a967601b157 Mon Sep 17 00:00:00 2001
From: Daniel P. Berrange <berrange@redhat.com>
Date: Thu, 5 Oct 2017 17:54:28 +0100
Subject: [PATCH] qemu: ensure TLS clients always verify the server certificate
The default_tls_x509_verify (and related) parameters in qemu.conf
control whether the QEMU TLS servers request & verify certificates
from clients. This works as a simple access control system for
servers by requiring the CA to issue certs to permitted clients.
This use of client certificates is disabled by default, since it
requires extra work to issue client certificates.
Unfortunately the code was using this configuration parameter when
setting up both TLS clients and servers in QEMU. The result was that
TLS clients for character devices and disk devices had verification
turned off, meaning they would ignore errors while validating the
server certificate.
This allows for trivial MITM attacks between client and server,
as any certificate returned by the attacker will be accepted by
the client.
This is assigned CVE-2017-1000256 / LSN-2017-0002
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
src/qemu/qemu_command.c | 2 +-
.../qemuxml2argv-serial-tcp-tlsx509-chardev.args | 2 +-
...xml2argv-serial-tcp-tlsx509-secret-chardev.args | 2 +-
3 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 46f0bdd..f68b82d 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -721,7 +721,7 @@ qemuBuildTLSx509BackendProps(const char *tlspath,
if (virJSONValueObjectCreate(propsret,
"s:dir", path,
"s:endpoint", (isListen ? "server": "client"),
- "b:verify-peer", verifypeer,
+ "b:verify-peer", (isListen ? verifypeer : true),
NULL) < 0)
goto cleanup;
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-serial-tcp-tlsx509-chardev.args b/tests/qemuxml2argvdata/qemuxml2argv-serial-tcp-tlsx509-chardev.args
index 5aff773..ab5f7e2 100644
--- a/tests/qemuxml2argvdata/qemuxml2argv-serial-tcp-tlsx509-chardev.args
+++ b/tests/qemuxml2argvdata/qemuxml2argv-serial-tcp-tlsx509-chardev.args
@@ -26,7 +26,7 @@ server,nowait \
localport=1111 \
-device isa-serial,chardev=charserial0,id=serial0 \
-object tls-creds-x509,id=objcharserial1_tls0,dir=/etc/pki/libvirt-chardev,\
-endpoint=client,verify-peer=no \
+endpoint=client,verify-peer=yes \
-chardev socket,id=charserial1,host=127.0.0.1,port=5555,\
tls-creds=objcharserial1_tls0 \
-device isa-serial,chardev=charserial1,id=serial1 \
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-serial-tcp-tlsx509-secret-chardev.args b/tests/qemuxml2argvdata/qemuxml2argv-serial-tcp-tlsx509-secret-chardev.args
index 91f1fe0..2567abb 100644
--- a/tests/qemuxml2argvdata/qemuxml2argv-serial-tcp-tlsx509-secret-chardev.args
+++ b/tests/qemuxml2argvdata/qemuxml2argv-serial-tcp-tlsx509-secret-chardev.args
@@ -31,7 +31,7 @@ localport=1111 \
data=9eao5F8qtkGt+seB1HYivWIxbtwUu6MQtg1zpj/oDtUsPr1q8wBYM91uEHCn6j/1,\
keyid=masterKey0,iv=AAECAwQFBgcICQoLDA0ODw==,format=base64 \
-object tls-creds-x509,id=objcharserial1_tls0,dir=/etc/pki/libvirt-chardev,\
-endpoint=client,verify-peer=no,passwordid=charserial1-secret0 \
+endpoint=client,verify-peer=yes,passwordid=charserial1-secret0 \
-chardev socket,id=charserial1,host=127.0.0.1,port=5555,\
tls-creds=objcharserial1_tls0 \
-device isa-serial,chardev=charserial1,id=serial1 \
--
1.7.1