From e8fa75ce061c1dddd607a8b1fd77ba1f09f4b9e0 Mon Sep 17 00:00:00 2001
From: Thomas Haller <thaller@redhat.com>
Date: Mon, 10 Sep 2018 15:45:04 +0200
Subject: [PATCH] dhcp: abort DHCP on devices without MAC address early

Internal DHCPv4 client requires a valid MAC address for functioning.
Just always require a MAC address to start DHCP, both v4 and v6.

We have no MAC address for example on Layer3 devices like tun or wireguard.

Also, before "34af574d58 systemd/dhcp: fix assertion starting DHCP
client without MAC address", if we tired to start sd_dhcp_client without
setting a MAC address, an assertion was triggered.
---
 src/dhcp/nm-dhcp-manager.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/src/dhcp/nm-dhcp-manager.c b/src/dhcp/nm-dhcp-manager.c
index 2fa86f7c98..6c71af9d0b 100644
--- a/src/dhcp/nm-dhcp-manager.c
+++ b/src/dhcp/nm-dhcp-manager.c
@@ -178,6 +178,7 @@ client_start (NMDhcpManager *self,
 	NMDhcpManagerPrivate *priv;
 	NMDhcpClient *client;
 	gboolean success = FALSE;
+	gsize hwaddr_len;
 
 	g_return_val_if_fail (NM_IS_DHCP_MANAGER (self), NULL);
 	g_return_val_if_fail (ifindex > 0, NULL);
@@ -185,6 +186,22 @@ client_start (NMDhcpManager *self,
 	g_return_val_if_fail (!dhcp_client_id || g_bytes_get_size (dhcp_client_id) >= 2, NULL);
 	g_return_val_if_fail (!error || !*error, NULL);
 
+	if (!hwaddr) {
+		nm_utils_error_set (error,
+		                    NM_UTILS_ERROR_UNKNOWN,
+		                    "missing MAC address");
+		return NULL;
+	}
+
+	hwaddr_len = g_bytes_get_size (hwaddr);
+	if (   hwaddr_len == 0
+	    || hwaddr_len > NM_UTILS_HWADDR_LEN_MAX) {
+		nm_utils_error_set (error,
+		                    NM_UTILS_ERROR_UNKNOWN,
+		                    "invalid MAC address");
+		g_return_val_if_reached (NULL) ;
+	}
+
 	priv = NM_DHCP_MANAGER_GET_PRIVATE (self);
 
 	nm_assert (priv->client_factory);