From: Rafał Miłecki <ra...@milecki.pl>
1. Create "rootfs_data" dynamicaly
U-Boot firmware images can contain only kernel and rootfs volume
(squashfs in case of OpenWrt). There is no way to include "rootfs_data"
UBI volume or make firmware file tell U-Boot to create one.
For that reason "rootfs_data" needs to be created dynamically. Use
preinit script to handle that. Fire it right before "mount_root" one.
2. Relate "rootfs_data" to flashed firmware
As already explained flashing new firmware with U-Boot will do nothing
to the "rootfs_data". It could result in new firmware reusing old
overlay UBI volume and its file. Users expect a clean state after
flashing firmware (even if flashing the same one).
Solve that by reading flash counter of running firmware and storing it
in "rootfs_data" UBI volume. Every mismatch will result in wiping old
data.
Signed-off-by: Rafał Miłecki <ra...@milecki.pl>
---
Used "overlay_verify" file requires pending fstools change:
[PATCH fstools] libfstools: support custom executable validating overlay
An alternative way would be to mount ubifs manually in preinit script.
That would be a bit hacky but wouldn't require fstools to call that
custom validation script.
Felix suggested validation script however.
---
.../base-files/lib/preinit/75_rootfs_prepare | 19 +++++++
.../base-files/usr/libexec/overlay_verify | 57 +++++++++++++++++++
2 files changed, 76 insertions(+)
create mode 100644
target/linux/bcm4908/base-files/lib/preinit/75_rootfs_prepare
create mode 100755 target/linux/bcm4908/base-files/usr/libexec/overlay_verify
diff --git a/target/linux/bcm4908/base-files/lib/preinit/75_rootfs_prepare
b/target/linux/bcm4908/base-files/lib/preinit/75_rootfs_prepare
new file mode 100644
index 0000000000..70bd71eea8
--- /dev/null
+++ b/target/linux/bcm4908/base-files/lib/preinit/75_rootfs_prepare
@@ -0,0 +1,19 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+rootfs_prepare() {
+ local blocks
+
+ ubinfo /dev/ubi0 -N rootfs_data > /dev/null 2>&1 && return
+
+ blocks=$(cat /sys/class/ubi/ubi0/avail_eraseblocks)
+ [ -z "$blocks" ] && {
+ echo "Failed to read amount of available erase blocks"
+ return
+ }
+
+ # Use 80% of remaining flash size for "rootfs_data"
+ ubimkvol /dev/ubi0 -n 20 -N rootfs_data --lebs $((blocks / 100 * 80))
+ mknod -m 0600 /dev/ubi0_20 c 252 21
+}
+
+boot_hook_add preinit_main rootfs_prepare
diff --git a/target/linux/bcm4908/base-files/usr/libexec/overlay_verify
b/target/linux/bcm4908/base-files/usr/libexec/overlay_verify
new file mode 100755
index 0000000000..02b2f48ca7
--- /dev/null
+++ b/target/linux/bcm4908/base-files/usr/libexec/overlay_verify
@@ -0,0 +1,57 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-only
+
+FS_STATE_READY=2
+
+# $(1): file to read from
+# $(2): offset in bytes
+get_hex_u32_le() {
+ dd if="$1" skip=$2 bs=1 count=4 2>/dev/null | hexdump -v -e '1/4 "%02x"'
+}
+
+platform_pkgtb_setup_env_config() {
+ local size=$((0x$(get_hex_u32_le /dev/ubi0_1 4)))
+
+ dd if=/dev/ubi0_1 of=/tmp/env.head count=8 iflag=count_bytes
+ dd if=/dev/ubi0_1 of=/tmp/env.body skip=8 iflag=skip_bytes
+ printf "%s\t0x%x\t0x%x\t0x%x" "/tmp/env.body" 0x0 $size $size >
/tmp/env.config
+}
+
+image_seq() {
+ platform_pkgtb_setup_env_config
+
+ commited="$(fw_printenv -n -c /tmp/env.config COMMITTED)"
+ [ -n "$commited" ] && {
+ seq=$(fw_printenv -n -c /tmp/env.config SEQ | cut -d ',' -f
$commited)
+ [ -n "$seq" ] && {
+ echo $seq
+ return
+ }
+ }
+
+ echo "Failed to read COMMITED and SEQ from metadata1" >&2
+ # Maybe this isn't U-Boot after all?
+ # Let booting try to proceed
+ exit 0
+}
+
+# Do nothing on CFE devices
+ubinfo /dev/ubi0 -N metadata1 > /dev/null 2>&1 || exit 0
+
+image_seq="$(image_seq)"
+
+# Wipe rootfs_data if it doesn't belong to us
+[ "$(readlink $1/.openwrt-image-seq)" != "$image_seq" ] && {
+ echo "Erasing old \"rootfs_data\""
+ rm -fR $1/*
+}
+
+# If rootfs_data is clean (or was just wiped) claim it
+[ -z "$(ls -A $1)" ] && {
+ # Claim this "rootfs_data"
+ ln -s $image_seq $1/.openwrt-image-seq
+ # Mark it readt to avoid "mount_root" wiping it again
+ ln -s $FS_STATE_READY $1/.fs_state
+}
+
+exit 0
--
2.31.1
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