ipq40xx: sysupgrade: allow flashing Linksys factory firmware

Allow forced flashing of a factory firmware image, after checking for the
correct FIT magic header and Linksys board-specific footer. Details of the
footer are already described in scripts/linksys-image.sh.

This is convenient as it avoids using a TFTP server or OEM GUI, and allows
restoring OEM firmware or installing a "breaking" OpenWrt update (e.g DSA
migration and kernel repartition) directly from the command line.

Devices supported at this time include EA6350v3, EA8300, MR8300 and WHW01.

Reviewed-by: Robert Marko <robimarko@gmail.com>
Tested-by:  Wyatt Martin <wawowl@gmail.com> # WHW01
Tested-by:  Tony Ambardar <itugrok@yahoo.com> # EA6350v3
Signed-off-by: Tony Ambardar <itugrok@yahoo.com>

diff --git a/target/linux/ipq40xx/base-files/lib/upgrade/linksys.sh b/target/linux/ipq40xx/base-files/lib/upgrade/linksys.sh
old mode 100755 (executable)
new mode 100644 (file)
index f1dc81f..5d25c20
--- a/target/linux/ipq40xx/base-files/lib/upgrade/linksys.sh
+++ b/target/linux/ipq40xx/base-files/lib/upgrade/linksys.sh
@@ -47,6 +47,14 @@ linksys_get_target_firmware() {
        esac
 }
 
+linksys_is_factory_image() {
+       local board=$(board_name)
+       board=${board##*,}
+
+       # check matching footer signature
+       tail -c 256 $1 | grep -q -i "\.LINKSYS\.........${board}"
+}
+
 platform_do_upgrade_linksys() {
        local magic_long="$(get_magic_long "$1")"
 
@@ -99,4 +107,14 @@ platform_do_upgrade_linksys() {
                echo "writing \"$1\" image to \"$part_label\""
                get_image "$1" | mtd write - "$part_label"
        }
+
+       [ "$magic_long" = "d00dfeed" ] && {
+               if ! linksys_is_factory_image "$1"; then
+                       echo "factory image doesn't match device"
+                       return 1
+               fi
+
+               echo "writing \"$1\" factory image to \"$part_label\""
+               get_image "$1" | mtd -e "$part_label" write - "$part_label"
+       }
 }