[OpenWrt-Devel] [PATCH] brcm2708: Implement sysupgrade image check

[Christian Lamparter]

Implement a crude but functioning sysupgrade image check for Raspberry Pi.
The code only checks if the master boot record boot signature (0x55aa) is
present in the first 512-bytes at the correct location. This can prevent
the odd, accidental bricking of a system when flashing the wrong file.

The platform check supports both gzipped and raw images.

Signed-off-by: Christian Lamparter <chunkeey at googlemail.com>
---
 .../linux/brcm2708/base-files/lib/upgrade/platform.sh   | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/target/linux/brcm2708/base-files/lib/upgrade/platform.sh b/target/linux/brcm2708/base-files/lib/upgrade/platform.sh
index 1d4b694..88c30cc 100644
--- a/target/linux/brcm2708/base-files/lib/upgrade/platform.sh
+++ b/target/linux/brcm2708/base-files/lib/upgrade/platform.sh
@@ -1,5 +1,20 @@
+get_magic_at() {
+	local file=$1
+	local pos=$2
+	( gunzip -c $file 2>/dev/null || cat $file 2>/dev/null ) | dd bs=1 count=2 skip=$pos 2>/dev/null | hexdump -v -n 2 -e '1/1 "%02x"'
+}
+
 platform_check_image() {
-	# i know no way to verify the image
+	local file=$1
+	local magic
+
+	magic=$(get_magic_at $file 510)
+
+	[ "$magic" != "55aa" ] && {
+		echo "Failed to verify MBR boot signature."
+		return 1
+	}
+
 	return 0;
 }
 
-- 
2.8.0.rc3
_______________________________________________
openwrt-devel mailing list
openwrt-devel at lists.openwrt.org
https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel