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Backport upstream MR2785 to add byte-swapped support

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Xwayland now disallows byte-swapped clients by default on Fedora 38 and
above.

This adds the ability to re-enable support for byte-swapped client
support in Xwayland if needed.

Related: #2159489
This commit is contained in:
Olivier Fourdan 2023-01-17 14:17:43 +01:00
parent 89161ff785
commit d55d552a7b
3 changed files with 222 additions and 1 deletions
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122
0001-settings-Add-Xwayland-byte-swapped-clients.patch Normal file
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@ -0,0 +1,122 @@
From 865edafa80f474942e04c18ece9dfafd48b777d1 Mon Sep 17 00:00:00 2001
From: Olivier Fourdan <ofourdan@redhat.com>
Date: Mon, 9 Jan 2023 15:35:52 +0100
Subject: [PATCH 1/2] settings: Add Xwayland byte-swapped clients
Recent versions of Xwayland can allow or disallow X11 clients from
different endianess to connect.
Add a setting to configure this feature from mutter, who spawns
Xwayland.
---
data/org.gnome.mutter.wayland.gschema.xml.in | 24 ++++++++++++++++++++
src/backends/meta-settings-private.h | 2 ++
src/backends/meta-settings.c | 23 +++++++++++++++++++
3 files changed, 49 insertions(+)
diff --git a/data/org.gnome.mutter.wayland.gschema.xml.in b/data/org.gnome.mutter.wayland.gschema.xml.in
index 8a1878e10..3c3e54498 100644
--- a/data/org.gnome.mutter.wayland.gschema.xml.in
+++ b/data/org.gnome.mutter.wayland.gschema.xml.in
@@ -125,6 +125,30 @@
</description>
</key>
+ <key name="xwayland-allow-byte-swapped-clients" type="b">
+ <default>false</default>
+ <summary>Allow X11 clients with a different endianess to connect to Xwayland</summary>
+ <description>
+ Allow connections from clients with an endianess different to that
+ of Xwayland.
+
+ The X server byte-swapping code is a huge attack surface, much of
+ that code in Xwayland is prone to security issues.
+
+ The use-case of byte-swapped clients is very niche, and disabled by
+ default in Xwayland.
+
+ Enable this option to instruct Xwayland to accept connections from
+ X11 clients with a different endianess.
+
+ This option has no effect if Xwayland does not support the command
+ line option +byteswappedclients/-byteswappedclients to control that
+ setting.
+
+ Xwayland needs to be restarted for this setting to take effect.
+ </description>
+ </key>
+
</schema>
</schemalist>
diff --git a/src/backends/meta-settings-private.h b/src/backends/meta-settings-private.h
index 47d2d6074..87af21515 100644
--- a/src/backends/meta-settings-private.h
+++ b/src/backends/meta-settings-private.h
@@ -77,6 +77,8 @@ gboolean meta_settings_are_xwayland_grabs_allowed (MetaSettings *settings);
int meta_settings_get_xwayland_disable_extensions (MetaSettings *settings);
+gboolean meta_settings_are_xwayland_byte_swapped_clients_allowed (MetaSettings *settings);
+
gboolean meta_settings_is_privacy_screen_enabled (MetaSettings *settings);
void meta_settings_set_privacy_screen_enabled (MetaSettings *settings,
diff --git a/src/backends/meta-settings.c b/src/backends/meta-settings.c
index 2826ff98f..8d3d624cc 100644
--- a/src/backends/meta-settings.c
+++ b/src/backends/meta-settings.c
@@ -75,6 +75,9 @@ struct _MetaSettings
/* A bitmask of MetaXwaylandExtension enum */
int xwayland_disable_extensions;
+
+ /* Whether Xwayland should allow X11 clients from different endianess */
+ gboolean xwayland_allow_byte_swapped_clients;
};
G_DEFINE_TYPE (MetaSettings, meta_settings, G_TYPE_OBJECT)
@@ -429,6 +432,15 @@ update_privacy_settings (MetaSettings *settings)
settings);
}
+static void
+update_xwayland_allow_byte_swapped_clients (MetaSettings *settings)
+{
+
+ settings->xwayland_allow_byte_swapped_clients =
+ g_settings_get_flags (settings->wayland_settings,
+ "xwayland-allow-byte-swapped-clients");
+}
+
static void
wayland_settings_changed (GSettings *wayland_settings,
gchar *key,
@@ -447,6 +459,10 @@ wayland_settings_changed (GSettings *wayland_settings,
{
update_xwayland_disable_extensions (settings);
}
+ else if (g_str_equal (key, "xwayland-allow-byte-swapped-clients"))
+ {
+ update_xwayland_allow_byte_swapped_clients (settings);
+ }
}
void
@@ -470,6 +486,13 @@ meta_settings_get_xwayland_disable_extensions (MetaSettings *settings)
return (settings->xwayland_disable_extensions);
}
+gboolean
+meta_settings_are_xwayland_byte_swapped_clients_allowed (MetaSettings *settings)
+{
+
+ return settings->xwayland_allow_byte_swapped_clients;
+}
+
gboolean
meta_settings_is_privacy_screen_enabled (MetaSettings *settings)
{
--
2.39.0

88
0002-xwayland-Add-support-for-byte-swapped-clients.patch Normal file
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@ -0,0 +1,88 @@
From 30ab9247f57b270d46b1c2c5c194f834bf8aafff Mon Sep 17 00:00:00 2001
From: Olivier Fourdan <ofourdan@redhat.com>
Date: Mon, 9 Jan 2023 15:40:03 +0100
Subject: [PATCH 2/2] xwayland: Add support for byte-swapped clients
Instructs Xwayland to allow/disallow connections from X11 clients with a
different endianess based on the "xwayland-allow-byte-swapped-clients"
setting.
This option has no effect if Xwayland does not support the command
option +byteswappedclients/-byteswappedclients.
Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/2576
---
config.h.meson | 3 +++
meson.build | 12 ++++++++++++
src/wayland/meta-xwayland.c | 7 +++++++
3 files changed, 22 insertions(+)
diff --git a/config.h.meson b/config.h.meson
index c7724b24f..5f9ea696e 100644
--- a/config.h.meson
+++ b/config.h.meson
@@ -109,3 +109,6 @@
/* Whether the Xwayland -terminate supports a delay */
#mesondefine HAVE_XWAYLAND_TERMINATE_DELAY
+
+/* Whether the Xwayland supports +/-byteswappedclients */
+#mesondefine HAVE_XWAYLAND_BYTE_SWAPPED_CLIENTS
diff --git a/meson.build b/meson.build
index 07460c0f1..a9608a9fd 100644
--- a/meson.build
+++ b/meson.build
@@ -526,6 +526,7 @@ endif
have_xwayland_initfd = false
have_xwayland_listenfd = false
have_xwayland_terminate_delay = false
+have_xwayland_byte_swapped_clients = false
if have_xwayland
xwayland_dep = dependency('xwayland', required: false)
@@ -587,6 +588,16 @@ if have_xwayland
if (have_xwayland_terminate_delay)
cdata.set('HAVE_XWAYLAND_TERMINATE_DELAY', 1)
endif
+
+ # For Xwayland +/-byteswappedclients usage
+ if xwayland_dep.found()
+ have_xwayland_byte_swapped_clients = xwayland_dep.get_variable('have_byteswappedclients',
+ default_value: 'false') == 'true'
+ endif
+
+ if (have_xwayland_byte_swapped_clients)
+ cdata.set('HAVE_XWAYLAND_BYTE_SWAPPED_CLIENTS', 1)
+ endif
endif
have_xsetioerrorexithandler = false
@@ -675,6 +686,7 @@ summary('Xwayland initfd', have_xwayland_initfd, section: 'Options')
summary('Xwayland listenfd', have_xwayland_listenfd, section: 'Options')
summary('Safe X11 I/O errors', have_xsetioerrorexithandler, section: 'Options')
summary('Xwayland terminate delay', have_xwayland_terminate_delay, section: 'Options')
+summary('Xwayland byte-swapped clients', have_xwayland_byte_swapped_clients, section: 'Options')
summary('Enabled', have_tests, section: 'Tests')
summary('Core tests', have_core_tests, section: 'Tests')
diff --git a/src/wayland/meta-xwayland.c b/src/wayland/meta-xwayland.c
index c9d94b2e3..8e8de1441 100644
--- a/src/wayland/meta-xwayland.c
+++ b/src/wayland/meta-xwayland.c
@@ -880,6 +880,13 @@ meta_xwayland_start_xserver (MetaXWaylandManager *manager,
args[i++] = "7";
#endif
+#ifdef HAVE_XWAYLAND_BYTE_SWAPPED_CLIENTS
+ if (meta_settings_are_xwayland_byte_swapped_clients_allowed (settings))
+ args[i++] = "+byteswappedclients";
+ else
+ args[i++] = "-byteswappedclients";
+#endif
+
if (meta_settings_is_experimental_feature_enabled (settings,
META_EXPERIMENTAL_FEATURE_AUTOCLOSE_XWAYLAND))
#ifdef HAVE_XWAYLAND_TERMINATE_DELAY
--
2.39.0

13
mutter.spec
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@ -12,7 +12,7 @@
Name: mutter
Version: 43.1
Release: 2%{?dist}
Release: 3%{?dist}
Summary: Window and compositing manager based on Clutter
License: GPLv2+
@ -35,6 +35,14 @@ Patch2: mutter-42.alpha-disable-tegra.patch
# https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2687
Patch3: post-43.1-fixes.patch
# Only on F38 and later
%if 0%{fedora} >= 38
# Add Xwayland byte-swapped clients support
# https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2785
Patch4: 0001-settings-Add-Xwayland-byte-swapped-clients.patch
Patch5: 0002-xwayland-Add-support-for-byte-swapped-clients.patch
%endif
BuildRequires: pkgconfig(gobject-introspection-1.0) >= 1.41.0
BuildRequires: pkgconfig(sm)
BuildRequires: pkgconfig(libwacom)
@ -180,6 +188,9 @@ desktop-file-validate %{buildroot}/%{_datadir}/applications/%{name}.desktop
%{_datadir}/mutter-%{mutter_api_version}/tests
%changelog
* Tue Jan 17 2023 Olivier Fourdan <ofourdan@redhat.com> - 43.1-3
- Add Xwayland byte-swapped clients support on Fedora 38 and above (#2159489)
* Thu Nov 17 2022 Jonas Ådahl <jadahl@redhat.com> - 43.1-2
- Backport regression fixes