netboot: Send client architecture and handle path prefix

Client architecture aware DHCP configurations may send a
bootfile for the wrong architecture, if the DHCP request
doesn't include the client architecture identifier 0x001f.

Further, the DHCP reply may include the pxepathprefix option,
which points to the base directory to use for TFT requests.
If the value is not honored by the client, the wrong
configuration file, kernel, etc. could be loaded.

Both issues are fixed by this commit.

Signed-off-by: Viktor Mihajlovski <mihajlov@linux.vnet.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

CHANGELOG.md

@@ -9,6 +9,7 @@ Release history for s390-tools (MIT version)
   Bug Fixes:
   - mon_procd: fix parsing of /proc/<pid>/stat
   - netboot: Include compressed kernel modules in initramfs
+  - netboot: Send client architecture and handle path prefix
 
  * __v2.5.0 (2018-06-08)__
 

netboot/mk-pxelinux-ramfs

@@ -170,7 +170,7 @@ cat <<'EOF' > $builddir/init
 /bin/mount -t tmpfs none /run
 
 /sbin/modprobe virtio_net
-/sbin/udhcpc -O pxeconffile -O pxepathprefix &
+/sbin/udhcpc -O pxeconffile -O pxepathprefix -x 93:001F &
 
 /sbin/pxeboot.script
 EOF
@@ -237,6 +237,7 @@ case "$1" in
 	echo " router: $router"
 	echo " domain: $domain $dns"
 	echo " tftp: $siaddr"
+	echo " pxepathprefix: $pxepathprefix"
 	# flush routes
 	/sbin/ip route flush table all
 	# setup if link
@@ -272,6 +273,7 @@ case "$1" in
 	    echo "siaddr=$siaddr" > $PXECONF
 	    echo "interface=$interface" >> $PXECONF
 	    echo "ip=$ip" >> $PXECONF
+	    echo "pxepathprefix=$pxepathprefix" >> $PXECONF
 	fi
 	;;
 
@@ -354,7 +356,7 @@ then
     for c in $CONFIGS
     do
 	echo "fetching config pxelinux.cfg/$c from $siaddr"
-	if /usr/bin/tftp -g -l /tmp/config -r pxelinux.cfg/$c $siaddr
+	if /usr/bin/tftp -g -l /tmp/config -r ${pxepathprefix}pxelinux.cfg/$c $siaddr
 	then
 	    break
 	fi
@@ -378,13 +380,13 @@ then
     exit
 else
     echo fetch kernel $kernel from $siaddr
-    /usr/bin/tftp -g -l /tmp/kernel -r $kernel $siaddr
+    /usr/bin/tftp -g -l /tmp/kernel -r $pxepathprefix$kernel $siaddr
 fi
 
 if [ -n "$initrd" ]
 then
     echo fetch initrd $initrd from $siaddr
-    /usr/bin/tftp -g -l /tmp/initrd -r $initrd $siaddr
+    /usr/bin/tftp -g -l /tmp/initrd -r $pxepathprefix$initrd $siaddr
     INITRD="--initrd=/tmp/initrd"
 else
     INITRD=""