fix debian rootfs building on non-debian distros, detect newer binwalk

Author: ading2210

README.md

@@ -250,6 +250,20 @@ $ nmcli connection edit <your connection name>
 > activate
 ```
 
+#### My binwalk version is unsupported.
+
+[Binwalk](https://github.com/ReFirmLabs/binwalk) is a tool that the Shimboot build scripts use to find and extract the initramfs from the shim kernel. Newer versions of binwalk (v3.x and higher) were rewritten in Rust for performance reasons. However, the new version is still feature incomplete and does not work for Shimboot's purposes. 
+
+Therefore, you need the older version of binwalk (v2.x) which was written in Python. To install it, run the following commands:
+
+```
+git clone https://salsa.debian.org/pkg-security-team/binwalk.git -b debian/2.4.3+dfsg1-2 --depth=1
+cd binwalk
+sudo python3 setup.py install
+```
+
+See the old [binwalk install instructions](https://salsa.debian.org/pkg-security-team/binwalk/-/blob/debian/2.4.3+dfsg1-2/INSTALL.md?ref_type=tags) for more information.
+
 ## Copyright:
 Shimboot is licensed under the [GNU GPL v3](https://www.gnu.org/licenses/gpl-3.0.txt). 
 

build.sh

@@ -16,10 +16,15 @@ print_help() {
 }
 
 assert_root
-assert_deps "cpio binwalk pcregrep realpath cgpt mkfs.ext4 mkfs.ext2 fdisk lz4"
+assert_deps "cpio binwalk pcregrep realpath cgpt mkfs.ext4 mkfs.ext2 fdisk lz4 7z"
 assert_args "$3"
 parse_args "$@"
 
+if ! supported_binwalk; then 
+  print_error "your version of binwalk is unsupported. you need binwalk 2.3.4 or older"
+  exit 1
+fi
+
 output_path="$(realpath -m "${1}")"
 shim_path="$(realpath -m "${2}")"
 rootfs_dir="$(realpath -m "${3}")"

rootfs/opt/setup_rootfs.sh

@@ -26,6 +26,7 @@ custom_repo_domain="shimboot.ading.dev"
 sources_entry="deb [trusted=yes arch=$arch] ${custom_repo} ${release_name} main"
 
 export DEBIAN_FRONTEND="noninteractive"
+source /etc/profile
 
 #add shimboot repos
 echo -e "${sources_entry}\n$(cat /etc/apt/sources.list)" > /etc/apt/sources.list

shim_utils.sh

@@ -3,13 +3,24 @@
 #utilties for reading shim disk images
 
 run_binwalk() {
-  if binwalk -h | grep -- '--run-as' >/dev/null; then
-    binwalk "$@" --run-as=root
+  binwalk_cmd="python3 -m binwalk"
+  if ! $binwalk_cmd -h > /dev/null; then
+    binwalk_cmd="binwalk"
+  fi
+  if $binwalk_cmd -h | grep -- '--run-as' >/dev/null; then
+    $binwalk_cmd "$@" --run-as=root
   else
-    binwalk "$@"
+    $binwalk_cmd "$@"
   fi
 }
 
+#binwalk 3.x and newer is not supported
+#see https://github.com/ReFirmLabs/binwalk/issues/829
+supported_binwalk() {
+  #the --version flag only exists on the newer binwalk
+  ! binwalk --version >/dev/null 2>&1
+}
+
 #extract the initramfs from a kernel image
 extract_initramfs() {
   local kernel_bin="$1"