MSVSphere Packaging Team
1 year ago
parent
38a9c39451
commit
884accf9ba
@ -0,0 +1,292 @@
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From b159849e031000d1dbc1ab876b5fc78a3ce9b534 Mon Sep 17 00:00:00 2001
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From: hongjinghao <q1204531485@163.com>
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Date: Mon, 5 Jun 2023 18:17:06 +0100
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Subject: [PATCH 1/2] bus: Assign a serial number for messages from the driver
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Normally, it's enough to rely on a message being given a serial number
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by the DBusConnection just before it is actually sent. However, in the
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rare case where the policy blocks the driver from sending a message
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(due to a deny rule or the outgoing message quota being full), we need
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to get a valid serial number sooner, so that we can copy it into the
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DBUS_HEADER_FIELD_REPLY_SERIAL field (which is mandatory) in the error
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message sent to monitors. Otherwise, the dbus-daemon will crash with
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an assertion failure if at least one Monitoring client is attached,
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because zero is not a valid serial number to copy.
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This fixes a denial-of-service vulnerability: if a privileged user is
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monitoring the well-known system bus using a Monitoring client like
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dbus-monitor or `busctl monitor`, then an unprivileged user can cause
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denial-of-service by triggering this crash. A mitigation for this
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vulnerability is to avoid attaching Monitoring clients to the system
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bus when they are not needed. If there are no Monitoring clients, then
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the vulnerable code is not reached.
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Co-authored-by: Simon McVittie <smcv@collabora.com>
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Resolves: dbus/dbus#457
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---
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bus/connection.c | 15 +++++++++++++++
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dbus/dbus-connection-internal.h | 2 ++
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dbus/dbus-connection.c | 11 ++++++++++-
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3 files changed, 27 insertions(+), 1 deletion(-)
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diff --git a/bus/connection.c b/bus/connection.c
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index a41b790b..4d46992c 100644
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--- a/bus/connection.c
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+++ b/bus/connection.c
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@@ -2376,6 +2376,21 @@ bus_transaction_send_from_driver (BusTransaction *transaction,
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if (!dbus_message_set_sender (message, DBUS_SERVICE_DBUS))
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return FALSE;
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+ /* Make sure the message has a non-zero serial number, otherwise
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+ * bus_transaction_capture_error_reply() will not be able to mock up
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+ * a corresponding reply for it. Normally this would be delayed until
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+ * the first time we actually send the message out from a
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+ * connection, when the transaction is committed, but that's too late
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+ * in this case.
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+ */
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+ if (dbus_message_get_serial (message) == 0)
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+ {
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+ dbus_uint32_t next_serial;
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+
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+ next_serial = _dbus_connection_get_next_client_serial (connection);
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+ dbus_message_set_serial (message, next_serial);
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+ }
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+
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if (bus_connection_is_active (connection))
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{
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if (!dbus_message_set_destination (message,
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diff --git a/dbus/dbus-connection-internal.h b/dbus/dbus-connection-internal.h
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index 912b546e..747e6e54 100644
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--- a/dbus/dbus-connection-internal.h
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+++ b/dbus/dbus-connection-internal.h
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@@ -57,6 +57,8 @@ DBUS_PRIVATE_EXPORT
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DBusConnection * _dbus_connection_ref_unlocked (DBusConnection *connection);
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DBUS_PRIVATE_EXPORT
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void _dbus_connection_unref_unlocked (DBusConnection *connection);
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+DBUS_PRIVATE_EXPORT
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+dbus_uint32_t _dbus_connection_get_next_client_serial (DBusConnection *connection);
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void _dbus_connection_queue_received_message_link (DBusConnection *connection,
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DBusList *link);
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dbus_bool_t _dbus_connection_has_messages_to_send_unlocked (DBusConnection *connection);
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diff --git a/dbus/dbus-connection.c b/dbus/dbus-connection.c
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index 105bdf4e..34380293 100644
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--- a/dbus/dbus-connection.c
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+++ b/dbus/dbus-connection.c
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@@ -1461,7 +1461,16 @@ _dbus_connection_unref_unlocked (DBusConnection *connection)
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_dbus_connection_last_unref (connection);
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}
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-static dbus_uint32_t
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+/**
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+ * Allocate and return the next non-zero serial number for outgoing messages.
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+ *
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+ * This method is only valid to call from single-threaded code, such as
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+ * the dbus-daemon, or with the connection lock held.
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+ *
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+ * @param connection the connection
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+ * @returns A suitable serial number for the next message to be sent on the connection.
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+ */
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+dbus_uint32_t
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_dbus_connection_get_next_client_serial (DBusConnection *connection)
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{
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dbus_uint32_t serial;
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--
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2.40.1
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From 986611ad0f7f67a3693e5672cd66bc608c00b228 Mon Sep 17 00:00:00 2001
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From: Simon McVittie <smcv@collabora.com>
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Date: Mon, 5 Jun 2023 18:51:22 +0100
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Subject: [PATCH 2/2] monitor test: Reproduce dbus/dbus#457
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The exact failure mode reported in dbus/dbus#457 is quite difficult
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to achieve in a reliable way in a unit test, because we'd have to send
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enough messages to a client to fill up its queue, then stop that client
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from draining its queue, while still triggering a message that gets a
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reply from the bus driver. However, we can trigger the same crash in a
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slightly different way by not allowing the client to receive a
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particular message. I chose NameAcquired.
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Signed-off-by: Simon McVittie <smcv@collabora.com>
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---
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.../valid-config-files/forbidding.conf.in | 3 +
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test/monitor.c | 77 ++++++++++++++++---
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2 files changed, 71 insertions(+), 9 deletions(-)
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diff --git a/test/data/valid-config-files/forbidding.conf.in b/test/data/valid-config-files/forbidding.conf.in
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index d145613c..58b3cc6a 100644
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--- a/test/data/valid-config-files/forbidding.conf.in
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+++ b/test/data/valid-config-files/forbidding.conf.in
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@@ -24,5 +24,8 @@
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<allow send_interface="com.example.CannotUnicast2" send_broadcast="true"/>
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<deny receive_interface="com.example.CannotReceive"/>
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+
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+ <!-- Used to reproduce dbus#457 -->
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+ <deny receive_interface="org.freedesktop.DBus" receive_member="NameAcquired"/>
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</policy>
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</busconfig>
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diff --git a/test/monitor.c b/test/monitor.c
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index d5a54b00..846a980c 100644
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--- a/test/monitor.c
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+++ b/test/monitor.c
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@@ -155,6 +155,21 @@ static Config side_effects_config = {
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TRUE
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};
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+static dbus_bool_t
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+config_forbids_name_acquired_signal (const Config *config)
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+{
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+ if (config == NULL)
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+ return FALSE;
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+
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+ if (config->config_file == NULL)
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+ return FALSE;
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+
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+ if (strcmp (config->config_file, forbidding_config.config_file) == 0)
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+ return TRUE;
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+
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+ return FALSE;
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+}
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+
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static inline const char *
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not_null2 (const char *x,
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const char *fallback)
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@@ -253,9 +268,6 @@ do { \
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#define assert_name_acquired(m) \
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do { \
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- DBusError _e = DBUS_ERROR_INIT; \
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- const char *_s; \
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- \
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g_assert_cmpstr (dbus_message_type_to_string (dbus_message_get_type (m)), \
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==, dbus_message_type_to_string (DBUS_MESSAGE_TYPE_SIGNAL)); \
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g_assert_cmpstr (dbus_message_get_sender (m), ==, DBUS_SERVICE_DBUS); \
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@@ -265,7 +277,14 @@ do { \
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g_assert_cmpstr (dbus_message_get_signature (m), ==, "s"); \
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g_assert_cmpint (dbus_message_get_serial (m), !=, 0); \
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g_assert_cmpint (dbus_message_get_reply_serial (m), ==, 0); \
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+} while (0)
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+
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+#define assert_unique_name_acquired(m) \
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+do { \
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+ DBusError _e = DBUS_ERROR_INIT; \
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+ const char *_s; \
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\
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+ assert_name_acquired (m); \
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dbus_message_get_args (m, &_e, \
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DBUS_TYPE_STRING, &_s, \
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DBUS_TYPE_INVALID); \
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@@ -333,6 +352,21 @@ do { \
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g_assert_cmpint (dbus_message_get_reply_serial (m), !=, 0); \
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} while (0)
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+/* forbidding.conf does not allow receiving NameAcquired, so if we are in
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+ * that configuration, then dbus-daemon synthesizes an error reply to itself
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+ * and sends that to monitors */
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+#define expect_name_acquired_error(queue, in_reply_to) \
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+do { \
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+ DBusMessage *message; \
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+ \
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+ message = g_queue_pop_head (queue); \
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+ assert_error_reply (message, DBUS_SERVICE_DBUS, DBUS_SERVICE_DBUS, \
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+ DBUS_ERROR_ACCESS_DENIED); \
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+ g_assert_cmpint (dbus_message_get_reply_serial (message), ==, \
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+ dbus_message_get_serial (in_reply_to)); \
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+ dbus_message_unref (message); \
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+} while (0)
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+
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/* This is called after processing pending replies to our own method
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* calls, but before anything else.
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*/
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@@ -727,6 +761,11 @@ test_become_monitor (Fixture *f,
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test_assert_no_error (&f->e);
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g_assert_cmpint (ret, ==, DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER);
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+ /* If the policy forbids receiving NameAcquired, then we'll never
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+ * receive it, so behave as though we had */
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+ if (config_forbids_name_acquired_signal (f->config))
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+ got_unique = got_a = got_b = got_c = TRUE;
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+
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while (!got_unique || !got_a || !got_b || !got_c)
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{
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if (g_queue_is_empty (&f->monitored))
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@@ -1378,6 +1417,7 @@ test_dbus_daemon (Fixture *f,
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{
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DBusMessage *m;
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int res;
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+ size_t n_expected;
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if (f->address == NULL)
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return;
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@@ -1393,7 +1433,12 @@ test_dbus_daemon (Fixture *f,
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test_assert_no_error (&f->e);
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g_assert_cmpint (res, ==, DBUS_RELEASE_NAME_REPLY_RELEASED);
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- while (g_queue_get_length (&f->monitored) < 8)
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+ n_expected = 8;
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+
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+ if (config_forbids_name_acquired_signal (context))
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+ n_expected += 1;
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+
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+ while (g_queue_get_length (&f->monitored) < n_expected)
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test_main_context_iterate (f->ctx, TRUE);
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m = g_queue_pop_head (&f->monitored);
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@@ -1406,10 +1451,12 @@ test_dbus_daemon (Fixture *f,
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"NameOwnerChanged", "sss", NULL);
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dbus_message_unref (m);
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- /* FIXME: should we get this? */
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m = g_queue_pop_head (&f->monitored);
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- assert_signal (m, DBUS_SERVICE_DBUS, DBUS_PATH_DBUS, DBUS_INTERFACE_DBUS,
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- "NameAcquired", "s", f->sender_name);
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+ assert_name_acquired (m);
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+
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+ if (config_forbids_name_acquired_signal (f->config))
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+ expect_name_acquired_error (&f->monitored, m);
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+
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dbus_message_unref (m);
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m = g_queue_pop_head (&f->monitored);
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@@ -1631,8 +1678,14 @@ static void
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expect_new_connection (Fixture *f)
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{
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DBusMessage *m;
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+ size_t n_expected;
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- while (g_queue_get_length (&f->monitored) < 4)
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+ n_expected = 4;
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+
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+ if (config_forbids_name_acquired_signal (f->config))
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+ n_expected += 1;
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+
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+ while (g_queue_get_length (&f->monitored) < n_expected)
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test_main_context_iterate (f->ctx, TRUE);
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m = g_queue_pop_head (&f->monitored);
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@@ -1649,7 +1702,11 @@ expect_new_connection (Fixture *f)
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dbus_message_unref (m);
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m = g_queue_pop_head (&f->monitored);
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- assert_name_acquired (m);
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+ assert_unique_name_acquired (m);
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+
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+ if (config_forbids_name_acquired_signal (f->config))
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+ expect_name_acquired_error (&f->monitored, m);
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+
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dbus_message_unref (m);
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}
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@@ -1988,6 +2045,8 @@ main (int argc,
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setup, test_method_call, teardown);
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g_test_add ("/monitor/forbidden-method", Fixture, &forbidding_config,
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setup, test_forbidden_method_call, teardown);
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+ g_test_add ("/monitor/forbidden-reply", Fixture, &forbidding_config,
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+ setup, test_dbus_daemon, teardown);
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g_test_add ("/monitor/dbus-daemon", Fixture, NULL,
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setup, test_dbus_daemon, teardown);
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g_test_add ("/monitor/selective", Fixture, &selective_config,
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--
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2.40.1
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