Add script to wrap filesystem image in DDI

with a dm-verity hash-tree and signed root hash.

Signed-off-by: Jeremi Piotrowski <[email protected]>

wrap-verity.sh

@@ -0,0 +1,70 @@
+#!/bin/bash
+
+set -e 
+
+data=$1
+
+verity_hdr=$(veritysetup format $data ${data}.verity)
+root_hash=$(echo $(awk -F: '/Root hash:/ { print $2 }' <<<$verity_hdr))
+
+data_size=$(stat -c %s $data)
+hash_size=$(stat -c %s ${data}.verity)
+root_hash_front=${root_hash:0:32}
+root_hash_back=${root_hash:32:32}
+
+# 512-byte sectors
+data_sectors=$(( $data_size >> 9 ))
+hash_sectors=$(( $hash_size >> 9 ))
+data_type=4f68bce3-e8cd-4db1-96e7-fbcaf984b709
+hash_type=2c7357ed-ebd2-46d9-aec1-23d437ec2bf5
+
+openssl req -batch -new -x509 -sha256 -newkey rsa:2048 -nodes -out root_key.crt -keyout root_key.pem -days 3650
+echo -n "$root_hash" >${data}.roothash
+openssl smime -sign -nocerts -noattr -binary -in "${data}.roothash" -inkey "root_key.pem" -signer "root_key.crt" -outform der -out "${data}.roothash.p7s"
+
+cat <<EOF | tr -d '\n' >${data}.verity.sig 
+{"rootHash":"$root_hash","signature":"$(base64 -w 0 <${data}.roothash.p7s)"}
+EOF
+sig_size=$(stat -c %s ${data}.verity.sig)
+# rounded up to 4096 bytes
+sig_size=$(( ( $sig_size + 4095 ) / 4096 * 4096 ))
+sig_sectors=$(( $sig_size >> 9 ))
+sig_type=41092b05-9fc8-4523-994f-2def0408b176
+
+# signature + GPT header + PMBR (?)
+disk_size=$(( $data_size + $hash_size + 4096 + 2048 * 512 + 33 * 512))
+rm -f disk.img
+fallocate -l $disk_size disk.img
+
+as_hex() {
+  str=$1
+  printf "%.8s-%.4s-%.4s-%.4s-%.12s" \
+    "${str:0:8}" "${str:8:4}" "${str:12:4}" \
+    "${str:16:4}" "${str:20:12}"
+}
+data_uuid=$(as_hex $root_hash_front)
+hash_uuid=$(as_hex $root_hash_back)
+
+cat <<EOF >sda.sfdisk
+label: gpt
+unit: sectors
+sector-size: 512
+
+/dev/sda1 : start=2048,                                          size=      ${data_sectors}, type=${data_type}, uuid=${data_uuid}
+/dev/sda2 : start=$(( $data_sectors + 2048 )),                   size=      ${hash_sectors}, type=${hash_type}, uuid=${hash_uuid}
+/dev/sda3 : start=$(( ${hash_sectors} + $data_sectors + 2048 )), size=       ${sig_sectors}, type=${sig_type}
+EOF
+
+sfdisk disk.img <sda.sfdisk
+
+loop=$(sudo losetup --find --show disk.img)
+sudo partx -u $loop
+sudo dd bs=512 if=$data of=${loop}p1
+sudo dd bs=512 if=${data}.verity of=${loop}p2
+sudo dd bs=512 if=${data}.verity.sig of=${loop}p3
+sudo losetup -d $loop
+
+echo
+echo "Finished!"
+echo "Copy disk.img to /etc/extensions/$(basename $data)"
+echo "Copy root_key.crt to /etc/verity.d/root_key.crt"