Address the cases where a NIC has a different name in kdump kernel

A NIC may get a different name in the kdump kernel from 1st kernel
in cases like,
 - kernel assigned network interface names are not persistent e.g. [1]
 - there is an udev rule to rename the NIC in the 1st kernel but the
   kdump initrd may not have that rule e.g. [2]

If NM tries to match a NIC with a connection profile based on NIC name
i.e. connection.interface-name, it will fail the above bases. A simple
solution is to ask NM to match a connection profile by MAC address.
Note we don't need to do this for user-created NICs like vlan, bridge and
bond.

An remaining issue is passing the name of a NIC via the kdumpnic dracut
command line parameter which requires passing ifname=<interface>:<MAC> to
have fixed NIC name. But we can simply drop this requirement. kdumpnic
is needed because kdump needs to get the IP by NIC name and use the IP
to created a dumping folder named "{IP}-{DATE}". We can simply pass the
IP to the kdump kernel directly via a new dracut command line parameter
kdumpip instead. In addition to the benefit of simplifying the code,
there are other three benefits brought by this approach,
  - make use of whatever network to transfer the vmcore. Because  as long
    as we have the network to we don't care which NIC is active.
  - if obtained IP in the kdump kernel is different from the one in the
    1st kernel. "{IP}-{DATE}" would better tell where the dumped vmcore
    comes from.
  - without passing ifname=<interface>:<MAC> to kdump initrd, the
    issue of there are two interfaces with the same MAC address for
    Azure Hyper-V NIC SR-IOV [3] is resolved automatically.

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1121778
[2] https://bugzilla.redhat.com/show_bug.cgi?id=810107
[3] https://bugzilla.redhat.com/show_bug.cgi?id=1962421

Signed-off-by: Coiby Xu <coxu@redhat.com>
Reviewed-by: Thomas Haller <thaller@redhat.com>
Reviewed-by: Philipp Rudo <prudo@redhat.com>

dracut-kdump.sh

@@ -484,25 +484,28 @@ save_vmcore_dmesg_ssh()
 
 get_host_ip()
 {
-	if is_nfs_dump_target || is_ssh_dump_target; then
+
-		kdumpnic=$(getarg kdumpnic=)
+	if ! is_nfs_dump_target && ! is_ssh_dump_target; then
-		if [ -z "$kdumpnic" ]; then
+		return 0
-			derror "failed to get kdumpnic!"
-			return 1
-		fi
-		if ! kdumphost=$(ip addr show dev "$kdumpnic" | grep '[ ]*inet'); then
-			derror "wrong kdumpnic: $kdumpnic"
-			return 1
-		fi
-		kdumphost=$(echo "$kdumphost" | head -n 1 | awk '{print $2}')
-		kdumphost="${kdumphost%%/*}"
-		if [ -z "$kdumphost" ]; then
-			derror "wrong kdumpnic: $kdumpnic"
-			return 1
-		fi
-		HOST_IP=$kdumphost
 	fi
-	return 0
+
+	_kdump_remote_ip=$(getarg kdump_remote_ip=)
+
+	if [ -z "$_kdump_remote_ip" ]; then
+		derror "failed to get remote IP address!"
+		return 1
+	fi
+	_route=$(kdump_get_ip_route "$_kdump_remote_ip")
+	_netdev=$(kdump_get_ip_route_field "$_route" "dev")
+
+	if ! _kdumpip=$(ip addr show dev "$_netdev" | grep '[ ]*inet'); then
+		derror "Failed to get IP of $_netdev"
+		return 1
+	fi
+
+	_kdumpip=$(echo "$_kdumpip" | head -n 1 | awk '{print $2}')
+	_kdumpip="${_kdumpip%%/*}"
+	HOST_IP=$_kdumpip
 }
 
 read_kdump_confs()

dracut-module-setup.sh

@@ -237,26 +237,6 @@ kdump_get_perm_addr() {
     fi
 }
 
-# Prefix kernel assigned names with "kdump-". EX: eth0 -> kdump-eth0
-# Because kernel assigned names are not persistent between 1st and 2nd
-# kernel. We could probably end up with eth0 being eth1, eth0 being
-# eth1, and naming conflict happens.
-kdump_setup_ifname() {
-    local _ifname
-
-    # If ifname already has 'kdump-' prefix, we must be switching from
-    # fadump to kdump. Skip prefixing 'kdump-' in this case as adding
-    # another prefix may truncate the ifname. Since an ifname with
-    # 'kdump-' is already persistent, this should be fine.
-    if [[ $1 =~ eth* ]] && [[ ! $1 =~ ^kdump-* ]]; then
-        _ifname="kdump-$1"
-    else
-        _ifname="$1"
-    fi
-
-    echo "$_ifname"
-}
-
 apply_nm_initrd_generator_timeouts() {
     local _timeout_conf
 
@@ -304,6 +284,19 @@ _clone_nmconnection() {
     return 1
 }
 
+_match_nmconnection_by_mac() {
+    local _unique_id _dev _mac _mac_field
+
+    _unique_id=$1
+    _dev=$2
+
+    _mac=$(kdump_get_perm_addr "$_dev")
+    [[ $_mac != 'not set' ]] || return
+    _mac_field=$(nmcli --get-values connection.type connection show "$_unique_id").mac-address
+    nmcli connection modify --temporary "$_unique_id" "$_mac_field" "$_mac" &> >(ddebug)
+    nmcli connection modify --temporary "$_unique_id" "connection.interface-name" "" &> >(ddebug)
+}
+
 # Clone and modify NM connection profiles
 #
 # This function makes use of "nmcli clone" to automatically convert ifcfg-*
@@ -325,6 +318,10 @@ clone_and_modify_nmconnection() {
     use_ipv4_or_ipv6 "$_dev" "$_uuid"
 
     nmcli connection modify --temporary uuid "$_uuid" connection.wait-device-timeout 60000 &> >(ddebug)
+    # For physical NIC i.e. non-user created NIC, ask NM to match a
+    # connection profile based on MAC address
+    _match_nmconnection_by_mac "$_uuid" "$_dev"
+
     _cloned_nmconnection_file_path=$(nmcli --get-values UUID,FILENAME connection show | sed -n "s/^${_uuid}://p")
     _tmp_nmconnection_file_path=$_DRACUT_KDUMP_NM_TMP_DIR/$(basename "$_nmconnection_file_path")
     cp "$_cloned_nmconnection_file_path" "$_tmp_nmconnection_file_path"
@@ -528,19 +525,6 @@ kdump_setup_znet() {
     echo "rd.znet=${NETTYPE},${SUBCHANNELS},${_options} rd.znet_ifname=$_netdev:${SUBCHANNELS}" > "${initdir}/etc/cmdline.d/30znet.conf"
 }
 
-kdump_get_ip_route() {
-    local _route
-    if ! _route=$(/sbin/ip -o route get to "$1" 2>&1); then
-        derror "Bad kdump network destination: $1"
-        exit 1
-    fi
-    echo "$_route"
-}
-
-kdump_get_ip_route_field() {
-    echo "$1" | sed -n -e "s/^.*\<$2\>\s\+\(\S\+\).*$/\1/p"
-}
-
 kdump_get_remote_ip() {
     local _remote _remote_temp
     _remote=$(get_remote_host "$1")
@@ -557,14 +541,13 @@ kdump_get_remote_ip() {
 # Collect netifs needed by kdump
 # $1: destination host
 kdump_collect_netif_usage() {
-    local _destaddr _srcaddr _route _netdev kdumpnic
+    local _destaddr _srcaddr _route _netdev
     local _znet_netdev _znet_conpath
 
     _destaddr=$(kdump_get_remote_ip "$1")
     _route=$(kdump_get_ip_route "$_destaddr")
     _srcaddr=$(kdump_get_ip_route_field "$_route" "src")
     _netdev=$(kdump_get_ip_route_field "$_route" "dev")
-    kdumpnic=$(kdump_setup_ifname "$_netdev")
 
     _znet_netdev=$(find_online_znet_device)
     if [[ -n $_znet_netdev ]]; then
@@ -591,8 +574,8 @@ kdump_collect_netif_usage() {
         echo "rd.neednet" >> "${initdir}/etc/cmdline.d/50neednet.conf"
     fi
 
-    if [[ ! -f ${initdir}/etc/cmdline.d/60kdumpnic.conf ]]; then
+    if [[ ! -f ${initdir}/etc/cmdline.d/60kdumpip.conf ]]; then
-        echo "kdumpnic=$kdumpnic" > "${initdir}/etc/cmdline.d/60kdumpnic.conf"
+        echo "kdump_remote_ip=$_destaddr" > "${initdir}/etc/cmdline.d/60kdumpip.conf"
     fi
 
     if is_ipv6_address "$_srcaddr"; then

kdump-lib-initramfs.sh

@@ -163,3 +163,17 @@ is_lvm2_thinp_device()
 
 	[ -n "$_lvm2_thin_device" ]
 }
+
+kdump_get_ip_route()
+{
+	if ! _route=$(/sbin/ip -o route get to "$1" 2>&1); then
+		derror "Bad kdump network destination: $1"
+		exit 1
+	fi
+	echo "$_route"
+}
+
+kdump_get_ip_route_field()
+{
+	echo "$1" | sed -n -e "s/^.*\<$2\>\s\+\(\S\+\).*$/\1/p"
+}