From 86db3df6ac331558b8cf48ab3747cabc4f3c249c Mon Sep 17 00:00:00 2001
From: Thomas Haller <thaller@redhat.com>
Date: Tue, 31 Oct 2023 12:11:55 +0100
Subject: [PATCH] core: honor
 ID_NET_MANAGED_BY="org.freedesktop.NetworkManager" to manage device

If ID_NET_MANAGED_BY= attribute is set, we have an indication who is
responsible for the device. If this is set to anything but
"org.freedesktop.NetworkManager", then the device is unmanaged.

The effect is the same as setting NM_UNMANAGED= attribute. NM_UNMANAGED=
takes precedence over this setting.

See-also: https://github.com/systemd/systemd/issues/29768
See-also: https://github.com/systemd/systemd/pull/29782
---
 NEWS                             | 2 ++
 man/NetworkManager.xml           | 9 +++++++++
 src/libnm-platform/nm-platform.c | 9 +++++++++
 3 files changed, 20 insertions(+)

diff --git a/NEWS b/NEWS
index 0079fd8487..e7838bd35f 100644
--- a/NEWS
+++ b/NEWS
@@ -8,6 +8,8 @@ Overview of changes since NetworkManager-1.44
   should not be noticeable.
 * Honor udev property ID_NET_AUTO_LINK_LOCAL_ONLY=1 for enabling
   link local addresses on default wired connection.
+* Honor udev property ID_NET_MANAGED_BY to only manage an interface
+  when set to "org.freedesktop.NetworkManager".
 
 =============================================
 NetworkManager-1.44
diff --git a/man/NetworkManager.xml b/man/NetworkManager.xml
index 5c17bd52fc..ff1635cd29 100644
--- a/man/NetworkManager.xml
+++ b/man/NetworkManager.xml
@@ -193,6 +193,15 @@
         </para>
         </listitem>
       </varlistentry>
+      <varlistentry>
+        <term><varname>ID_NET_MANAGED_BY</varname></term>
+        <listitem><para>
+          If <varname>NM_UNMANAGED</varname> is set, this has no effect. Otherwise,
+          if the attribute is set to anything but
+          <literal>"org.freedesktop.NetworkManager"</literal>, the device is unmanaged.
+        </para>
+        </listitem>
+      </varlistentry>
       <varlistentry>
         <term><varname>NM_AUTO_DEFAULT_LINK_LOCAL_ONLY</varname></term>
         <listitem><para>
diff --git a/src/libnm-platform/nm-platform.c b/src/libnm-platform/nm-platform.c
index e55c749931..d5acec98f5 100644
--- a/src/libnm-platform/nm-platform.c
+++ b/src/libnm-platform/nm-platform.c
@@ -1673,6 +1673,15 @@ nm_platform_link_get_unmanaged(NMPlatform *self, int ifindex)
     if (val)
         return _nm_utils_ascii_str_to_bool(val, FALSE);
 
+    val = udev_device_get_property_value(udevice, "ID_NET_MANAGED_BY");
+    if (val) {
+        if (!nm_streq(val, "org.freedesktop.NetworkManager")) {
+            /* There is another manager. UNMANAGED. */
+            return TRUE;
+        }
+        return FALSE;
+    }
+
     return NM_OPTION_BOOL_DEFAULT;
 }