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authorDaniel P. Berrange <berrange@redhat.com>2016-07-27 14:13:56 +0100
committerDaniel P. Berrangé <berrange@redhat.com>2019-02-26 15:32:19 +0000
commit8953caf3cd38534f8f63f4250f4ba4b4da4ff543 (patch)
tree3330126de8d618fd3d07f777a8711666199cc727 /tests
parent55d869846de802a16af1a50584c51737bd664387 (diff)
authz: add QAuthZPAM object type for authorizing using PAM
Add an authorization backend that talks to PAM to check whether the user identity is allowed. This only uses the PAM account validation facility, which is essentially just a check to see if the provided username is permitted access. It doesn't use the authentication or session parts of PAM, since that's dealt with by the relevant part of QEMU (eg VNC server). Consider starting QEMU with a VNC server and telling it to use TLS with x509 client certificates and configuring it to use an PAM to validate the x509 distinguished name. In this example we're telling it to use PAM for the QAuthZ impl with a service name of "qemu-vnc" $ qemu-system-x86_64 \ -object tls-creds-x509,id=tls0,dir=/home/berrange/security/qemutls,\ endpoint=server,verify-peer=yes \ -object authz-pam,id=authz0,service=qemu-vnc \ -vnc :1,tls-creds=tls0,tls-authz=authz0 This requires an /etc/pam/qemu-vnc file to be created with the auth rules. A very simple file based whitelist can be setup using $ cat > /etc/pam/qemu-vnc <<EOF account requisite pam_listfile.so item=user sense=allow file=/etc/qemu/vnc.allow EOF The /etc/qemu/vnc.allow file simply contains one username per line. Any username not in the file is denied. The usernames in this example are the x509 distinguished name from the client's x509 cert. $ cat > /etc/qemu/vnc.allow <<EOF CN=laptop.berrange.com,O=Berrange Home,L=London,ST=London,C=GB EOF More interesting would be to configure PAM to use an LDAP backend, so that the QEMU authorization check data can be centralized instead of requiring each compute host to have file maintained. The main limitation with this PAM module is that the rules apply to all QEMU instances on the host. Setting up different rules per VM, would require creating a separate PAM service name & config file for every guest. An alternative approach for the future might be to not pass in the plain username to PAM, but instead combine the VM name or UUID with the username. This requires further consideration though. Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Diffstat (limited to 'tests')
-rw-r--r--tests/Makefile.include2
-rw-r--r--tests/test-authz-pam.c124
2 files changed, 126 insertions, 0 deletions
diff --git a/tests/Makefile.include b/tests/Makefile.include
index 9b63d4743c..8778e5145b 100644
--- a/tests/Makefile.include
+++ b/tests/Makefile.include
@@ -119,6 +119,7 @@ check-unit-y += tests/test-util-sockets$(EXESUF)
check-unit-y += tests/test-authz-simple$(EXESUF)
check-unit-y += tests/test-authz-list$(EXESUF)
check-unit-y += tests/test-authz-listfile$(EXESUF)
+check-unit-$(CONFIG_AUTH_PAM) += tests/test-authz-pam$(EXESUF)
check-unit-y += tests/test-io-task$(EXESUF)
check-unit-y += tests/test-io-channel-socket$(EXESUF)
check-unit-y += tests/test-io-channel-file$(EXESUF)
@@ -669,6 +670,7 @@ tests/test-util-sockets$(EXESUF): tests/test-util-sockets.o \
tests/test-authz-simple$(EXESUF): tests/test-authz-simple.o $(test-authz-obj-y)
tests/test-authz-list$(EXESUF): tests/test-authz-list.o $(test-authz-obj-y)
tests/test-authz-listfile$(EXESUF): tests/test-authz-listfile.o $(test-authz-obj-y)
+tests/test-authz-pam$(EXESUF): tests/test-authz-pam.o $(test-authz-obj-y)
tests/test-io-task$(EXESUF): tests/test-io-task.o $(test-io-obj-y)
tests/test-io-channel-socket$(EXESUF): tests/test-io-channel-socket.o \
tests/io-channel-helpers.o tests/socket-helpers.o $(test-io-obj-y)
diff --git a/tests/test-authz-pam.c b/tests/test-authz-pam.c
new file mode 100644
index 0000000000..93d5ac8bbf
--- /dev/null
+++ b/tests/test-authz-pam.c
@@ -0,0 +1,124 @@
+/*
+ * QEMU PAM authorization object tests
+ *
+ * Copyright (c) 2018 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "authz/pamacct.h"
+
+#include <security/pam_appl.h>
+
+static bool failauth;
+
+/*
+ * These two functions are exported by libpam.so.
+ *
+ * By defining them again here, our impls are resolved
+ * by the linker instead of those in libpam.so
+ *
+ * The test suite is thus isolated from the host system
+ * PAM setup, so we can do predictable test scenarios
+ */
+int
+pam_start(const char *service_name, const char *user,
+ const struct pam_conv *pam_conversation,
+ pam_handle_t **pamh)
+{
+ failauth = true;
+ if (!g_str_equal(service_name, "qemu-vnc")) {
+ return PAM_AUTH_ERR;
+ }
+
+ if (g_str_equal(user, "fred")) {
+ failauth = false;
+ }
+
+ return PAM_SUCCESS;
+}
+
+
+int
+pam_acct_mgmt(pam_handle_t *pamh, int flags)
+{
+ if (failauth) {
+ return PAM_AUTH_ERR;
+ }
+
+ return PAM_SUCCESS;
+}
+
+
+static void test_authz_unknown_service(void)
+{
+ Error *local_err = NULL;
+ QAuthZPAM *auth = qauthz_pam_new("auth0",
+ "qemu-does-not-exist",
+ &error_abort);
+
+ g_assert_nonnull(auth);
+
+ g_assert_false(qauthz_is_allowed(QAUTHZ(auth), "fred", &local_err));
+
+ error_free_or_abort(&local_err);
+ object_unparent(OBJECT(auth));
+}
+
+
+static void test_authz_good_user(void)
+{
+ QAuthZPAM *auth = qauthz_pam_new("auth0",
+ "qemu-vnc",
+ &error_abort);
+
+ g_assert_nonnull(auth);
+
+ g_assert_true(qauthz_is_allowed(QAUTHZ(auth), "fred", &error_abort));
+
+ object_unparent(OBJECT(auth));
+}
+
+
+static void test_authz_bad_user(void)
+{
+ Error *local_err = NULL;
+ QAuthZPAM *auth = qauthz_pam_new("auth0",
+ "qemu-vnc",
+ &error_abort);
+
+ g_assert_nonnull(auth);
+
+ g_assert_false(qauthz_is_allowed(QAUTHZ(auth), "bob", &local_err));
+
+ error_free_or_abort(&local_err);
+ object_unparent(OBJECT(auth));
+}
+
+
+int main(int argc, char **argv)
+{
+ g_test_init(&argc, &argv, NULL);
+
+ module_call_init(MODULE_INIT_QOM);
+
+ g_test_add_func("/auth/pam/unknown-service", test_authz_unknown_service);
+ g_test_add_func("/auth/pam/good-user", test_authz_good_user);
+ g_test_add_func("/auth/pam/bad-user", test_authz_bad_user);
+
+ return g_test_run();
+}