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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