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diff --git a/recipes-core/initrdscripts/COPYING.MIT b/recipes-core/initrdscripts/COPYING.MIT new file mode 100644 index 0000000..89de354 --- /dev/null +++ b/recipes-core/initrdscripts/COPYING.MIT @@ -0,0 +1,17 @@ +Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in +all copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN +THE SOFTWARE. diff --git a/recipes-core/initrdscripts/README.md b/recipes-core/initrdscripts/README.md new file mode 100644 index 0000000..a038dfa --- /dev/null +++ b/recipes-core/initrdscripts/README.md @@ -0,0 +1,162 @@ +# meta-readonly-rootfs-overlay + +This OpenEmbedded layer provides the necessary scripts and configurations to +setup a writable root file system overlay on top of a read-only root file system. + +## Why does this exists? + +Having a read-only root file system is useful for many scenarios: + +- Separate user specific changes from system configuration, and being able to +find differences +- Allow factory reset, by deleting the user specific changes +- Have a fallback image in case the user specific changes made the root file +system no longer bootable. + +Because some data on the root file system changes on first boot or while the +system is running, just mounting the complete root file system as read-only +breaks many applications. There are different solutions to this problem: + +- Symlinking/Bind mounting files and directories that could potentially change +while the system is running to a writable partition +- Instead of having a read-only root files system, mounting a writable overlay +root file system, that uses a read-only file system as its base and writes +changed data to another writable partition. + +To implement the first solution, the developer needs to analyse which file +needs to change and then create symlinks for them. When doing factory reset, +the developer needs to overwrite every file that is linked with the factory +configuration, to avoid dangling symlinks/binds. While this is more work on the +developer side, it might increase the security, because only files that are +symlinked/bind-mounted can be changed. However, IMO that is better left to file +permissions. + +This meta-layer provides the second solution. Here no investigation of writable +files are needed and factory reset can be done by just deleting all files or +formatting the writable volume. + +# Dependencies + +This layer depends on: + +``` + URI: git://git.openembedded.org/bitbake + branch: krogoth +``` + +``` + URI: git://git.openembedded.org/openembedded-core + layers: meta + branch: krogoth +``` + +# Patches + +Please submit any patches against the readonly-rootfs-overlay layer via pull +request. + + +# Table of Contents + +1. [Adding the readonly-rootfs-overlay layer to your build](#adding-the-readonly-rootfs-overlay-layer-to-your-build) +1. [Read-only root filesystem](#read-only-root-filesystem) +1. [Kernel command line parameters](#kernel-command-line-parameters) + + +## Adding the readonly-rootfs-overlay layer to your build + +In order to use this layer, you need to make the build system aware of +it. + +Assuming the readonly-rootfs-overlay layer exists at the top-level of your +OpenEmbedded source tree, you can add it to the build system by adding the +location of the readonly-rootfs-overlay layer to bblayers.conf, along with any +other layers needed. e.g.: + +``` + BBLAYERS ?= " \ + /path/to/layers/meta \ + /path/to/layers/meta-poky \ + /path/to/layers/meta-yocto-bsp \ + /path/to/layers/meta-readonly-rootfs-overlay \ + " +``` + +To add the script to your image, just add: + +``` + IMAGE_INSTALL_append = " initscripts-readonly-rootfs-overlay" +``` + +to your `local.conf` or image recipe. Or use +`core-image-rorootfs-overlay-initramfs` as initrd. + +## Read-only root filesystem + +If you use this layer you do *not* need to set `read-only-rootfs` in the +`IMAGE_FEATURES` or `EXTRA_IMAGE_FEATURES` variable. + +## Kernel command line parameters + +These examples are not meant to be complete. They just contain parameters that +are used by the initscript of this repository. Some additional paramters might +be necessary. + +### Example using initrd: + +``` +root=/dev/sda1 rootrw=/dev/sda2 +``` + +This cmd line start `/sbin/init` with the `/dev/sda1` partition as the read-only +rootfs and the `/dev/sda2` partition as the read-write persistent state. + +``` +root=/dev/sda1 rootrw=/dev/sda2 init=/bin/sh +``` + +The same as before but it now starts `/bin/sh` instead of `/sbin/init`. + +### Example without initrd: + +``` +root=/dev/sda1 rootrw=/dev/sda2 init=/init +``` + +This cmd line starts `/sbin/init` with `/dev/sda1` partition as the read-only +rootfs and the `/dev/sda2` partition as the read-write persistent state. When +using this init script without an initrd, `init=/init` has to be set. + +``` +root=/dev/sda1 rootrw=/dev/sda2 init=/init rootinit=/bin/sh +``` + +The same as before but it now starts `/bin/sh` instead of `/sbin/init` + +### Details + +`root=` specifies the read-only root file system device. If this is not +specified, the current rootfs is used. + +`rootfstype=` if support for the read-only file system is not build into the +kernel, you can specify the required module name here. It will also be used in +the mount command. + +`rootoptions=` specifies the mount options of the read-only file system. +Defaults to `noatime,nodiratime`. + +`rootinit=` if the `init` parameter was used to specify this init script, +`rootinit` can be used to overwrite the default (`/sbin/init`). + +`rootrw=` specifies the read-write file system device. If this is not +specified, `tmpfs` is used. + +`rootrwfstype=` if support for the read-write file system is not build into the +kernel, you can specify the required module name here. It will also be used in +the mount command. + +`rootrwoptions=` specifies the mount options of the read-write file system. +Defaults to `rw,noatime,mode=755`. + +`rootrwreset=` set to `yes` if you want to delete all the files in the +read-write file system prior to building the overlay root files system. diff --git a/recipes-core/initrdscripts/files/.init-readonly-rootfs-overlay-boot.sh.kate-swp b/recipes-core/initrdscripts/files/.init-readonly-rootfs-overlay-boot.sh.kate-swp Binary files differnew file mode 100644 index 0000000..4a52bfd --- /dev/null +++ b/recipes-core/initrdscripts/files/.init-readonly-rootfs-overlay-boot.sh.kate-swp diff --git a/recipes-core/initrdscripts/files/init-readonly-rootfs-overlay-boot.sh b/recipes-core/initrdscripts/files/init-readonly-rootfs-overlay-boot.sh new file mode 100755 index 0000000..6ec69ab --- /dev/null +++ b/recipes-core/initrdscripts/files/init-readonly-rootfs-overlay-boot.sh @@ -0,0 +1,326 @@ +#!/bin/bash +# fsck output of the upper file system (rw) is +# written to /dev/kmsg + +# Kernel arguments for this script: +# This script allows one to specify the root read-only device with +# kernel argument: +# root= +# What follows can be a PARTUUID, PARTLABEL, or some other mechanism +# understood by findfs, including the plain device name. +# +# The rw file system overlayed on top of root defaults to: +# rootrw='PARTLABEL=user_data' +# This is the first GPT partition found with the name user_data. +# +# Another file system can be specified by PARTUUID, or the +# plain device name, or anything understood by findfs. +# For instance: +# rootrw=/dev/mmcblk0p10 +# to use the SD card. +# +# fsck is not done to the root file system. It is assumed it cannot be +# corrupted. +# By default, fsck -p [rootrw device] is done. +# +# There are two kernel options governing fsck: +# +# fsck.repair=true|false|force +# false skips fsck, force adds the -f option. +# true is the default (fsck with no -f option) +# fsck.mode=preen|yes|no +# These represent -p, -y, and -n options. +# Preen (-p) is the default +# +# Additional options exist to specify the init program +# mount options, file system type. root_rwreset="yes" +# will cause the read/write file system to be erased. +# + + +# Enable strict shell mode +set -euo pipefail + +PATH=/sbin:/bin:/usr/sbin:/usr/bin + +MOUNT="/bin/mount" +UMOUNT="/bin/umount" + +INIT="/sbin/init" +ROOT_ROINIT="/sbin/init" + +ROOT_MOUNT="/mnt" +ROOT_RODEVICE="" +ROOT_RWDEVICE="" +ROOT_ROMOUNT="/run/media/rfs/ro" +ROOT_RWMOUNT="/run/media/rfs/rw" +ROOT_RWRESET="no" + +ROOT_ROFSTYPE="" +ROOT_ROMOUNTOPTIONS="bind" +ROOT_ROMOUNTOPTIONS_DEVICE="noatime,nodiratime,ro" + +ROOT_RWFSTYPE="" +ROOT_RWMOUNTOPTIONS="rw,noatime,mode=755 tmpfs" +ROOT_RWMOUNTOPTIONS_DEVICE="rw,noatime" + +# Arithmetic assignments of 0 are false, and then +# script uses set -e, so use let instead. +DO_FSCK=1 +DO_STOP=0 +FSCKOPT="-p" + + +finddevice() { + DEVICE="$1" + if dev=$(findfs "${DEVICE}") && ((${#dev})) ; then + # Replace the rootfs string with the findfs device result + log "Searched for ${DEVICE} and found $dev" + echo "$dev" + return 0 + fi + log "Could not find $DEVICE" + return 1 +} + +early_setup() { + mkdir -p /proc + mkdir -p /sys + $MOUNT -t proc proc /proc + $MOUNT -t sysfs sysfs /sys + grep -w "/dev" /proc/mounts >/dev/null || $MOUNT -t devtmpfs none /dev +} + +read_args() { + # Default is to do fsck with -p option on user_data partition. + [ -z "${CMDLINE+x}" ] && CMDLINE=`cat /proc/cmdline` + for arg in $CMDLINE; do + # Set optarg to option parameter, and '' if no parameter was + # given + optarg=`expr "x$arg" : 'x[^=]*=\(.*\)' || echo ''` + case $arg in + shinitramfs) + ((DO_STOP=1)) ;; + root=*) + ROOT_RODEVICE=$optarg + if rootdev=$(finddevice "${ROOT_RODEVICE}") ; then + # Replace the rootfs string with the findfs device result + ROOT_RODEVICE="${rootdev}" + fi + ;; + rootfstype=*) + ROOT_ROFSTYPE="$optarg" ;; + rootinit=*) + ROOT_ROINIT=$optarg ;; + rootoptions=*) + ROOT_ROMOUNTOPTIONS_DEVICE="$optarg" ;; + rootrw=*) + ROOT_RWDEVICE=$optarg + if rootrwdev="$(finddevice ${ROOT_RWDEVICE})" ; then + # Replace the rootfs string with the findfs device result + ROOT_RODEVICE="${rootrwdev}" + fi + ;; + rootrwfstype=*) + ROOT_RWFSTYPE="$optarg" ;; + rootrwreset=*) + ROOT_RWRESET=$optarg ;; + rootrwoptions=*) + ROOT_RWMOUNTOPTIONS_DEVICE="$optarg" ;; + init=*) + INIT=$optarg ;; + fsck.mode=*) + fsck_mode=$optarg + case $fsck_mode in + preen) + FSCKOPT="-p" ;; + yes) + FSCKOPT="-y" ;; + no) + FSCKOPT="-n" ;; + esac + ;; + fsck.repair=*) + fsck_repair=$optarg + case $fsck_repair in + force) + if ((${#FSCKOPT)) ; then + FSCKOPT+="f" + else + FSCKOPT="-f" + fi + DO_FSCK=1 + ;; + yes) + DO_FSCK=1 + ;; + no) + DO_FSCK=0 + ;; + esac + + ;; + esac + done +} + +fatal() { + echo "rorootfs-overlay: $1" >$CONSOLE + echo >$CONSOLE + exec bash +} + +log() { + echo "rorootfs-overlay: $1" >$CONSOLE +} + +early_setup + +[ -z "${CONSOLE+x}" ] && CONSOLE="/dev/console" + +read_args + +mount_and_boot() { + mkdir -p $ROOT_MOUNT $ROOT_ROMOUNT $ROOT_RWMOUNT + + # Build mount options for read only root file system. + # If no read-only device was specified via kernel command line, use + # current root file system via bind mount. + ROOT_ROMOUNTPARAMS_BIND="-o ${ROOT_ROMOUNTOPTIONS} /" + if [ -n "${ROOT_RODEVICE}" ]; then + ROOT_ROMOUNTPARAMS="-o ${ROOT_ROMOUNTOPTIONS_DEVICE} $ROOT_RODEVICE" + if [ -n "${ROOT_ROFSTYPE}" ]; then + ROOT_ROMOUNTPARAMS="-t $ROOT_ROFSTYPE $ROOT_ROMOUNTPARAMS" + fi + else + ROOT_ROMOUNTPARAMS="$ROOT_ROMOUNTPARAMS_BIND" + fi + + mountlog=$($MOUNT $ROOT_ROMOUNTPARAMS "$ROOT_ROMOUNT" 2>&1) + mountresult=$? + if ((mountresult != 0)) ; then + log "Failed root mount (result $mountresult): $mountlog" + log "mounts: $(cat /proc/mounts)" + else + log "Mounted ro root: $(grep "$ROOT_ROMOUNT" /proc/mounts)" + fi + + log "Mounted root: $(grep root /proc/mounts)" + + # If future init is the same as current file, use $ROOT_ROINIT + # Tries to avoid loop to infinity if init is set to current file via + # kernel command line + if cmp -s "$0" "$INIT"; then + INIT="$ROOT_ROINIT" + fi + + # find user_data + if [[ -z ${ROOT_RWDEVICE} ]] ; then + userdata=$(findfs PARTLABEL=user_data) + blkid_out=$(blkid $userdata) + if [[ -n $userdata ]] ; then + if [[ $blkid_out =~ TYPE=\"([^\"]+)\" ]]; then + log "Detected user_data partition with ${BASH_REMATCH[1]} file system" + else + log "Create new user_data partition ext4 file system" + mkfs.ext4 -O 64bit $userdata + fi + ROOT_RWDEVICE="$userdata" + fi # Found user_data GPT partition + fi # Empty ROOT_RWDEVICE + # Build mount options for read write root file system. + # If a read-write device was specified via kernel command line + # or partition table, use it, otherwise default to tmpfs. + if [ -n "${ROOT_RWDEVICE}" ]; then + ROOT_RWMOUNTPARAMS="-o $ROOT_RWMOUNTOPTIONS_DEVICE $ROOT_RWDEVICE" + if [ -n "${ROOT_RWFSTYPE}" ]; then + ROOT_RWMOUNTPARAMS="-t $ROOT_RWFSTYPE $ROOT_RWMOUNTPARAMS" + fi + else + ROOT_RWMOUNTPARAMS="-t tmpfs -o $ROOT_RWMOUNTOPTIONS" + fi + + if ((DO_FSCK == 1)) ; then + if log_result=$(fsck $FSCKOPT $ROOT_RWDEVICE 2>&1) ; then + log "OK fsck user_data: fsck $FSCKOPT $ROOT_RWDEVICE: $(fsck $FSCKOPT $ROOT_RWDEVICE 2>&1)" + echo "fsck user_data: $log_result" >/dev/kmsg + else + log "ERR fsck user_data: fsck $FSCKOPT $ROOT_RWDEVICE: $(fsck $FSCKOPT $ROOT_RWDEVICE 2>&1)" + log "$log_result" + # Write fsck to kernel log + echo "ERR fsck user_data: fsck $FSCKOPT $ROOT_RWDEVICE: $(fsck $FSCKOPT $ROOT_RWDEVICE 2>&1)" >/dev/kmsg + echo "$log_result" >/dev/kmsg + fi + fi + + # Mount read-write file system into initram root file system + if ! $MOUNT $ROOT_RWMOUNTPARAMS $ROOT_RWMOUNT ; then + fatal "Could not mount read-write rootfs" + fi + + # Reset read-write file system if specified + if [ "yes" == "$ROOT_RWRESET" -a -n "${ROOT_RWMOUNT}" ]; then + rm -rf $ROOT_RWMOUNT/* + fi + + # Determine which unification file system to use + union_fs_type="" + if grep -w "overlay" /proc/filesystems >/dev/null; then + union_fs_type="overlay" + elif grep -w "aufs" /proc/filesystems >/dev/null; then + union_fs_type="aufs" + else + union_fs_type="" + fi + + # Create/Mount overlay root file system + case $union_fs_type in + "overlay") + log "$(cat /proc/mounts)" + mkdir -p $ROOT_RWMOUNT/upperdir $ROOT_RWMOUNT/work + if ! $MOUNT -t overlay overlay \ + -o "$(printf "%s%s%s" \ + "lowerdir=$ROOT_ROMOUNT," \ + "upperdir=$ROOT_RWMOUNT/upperdir," \ + "workdir=$ROOT_RWMOUNT/work")" \ + $ROOT_MOUNT ; then + log "$MOUNT -t overlay overlay \ + -o \"$(printf \"%s%s%s\" \ + \"lowerdir=$ROOT_ROMOUNT,\" \ + \"upperdir=$ROOT_RWMOUNT/upperdir,\" \ + \"workdir=$ROOT_RWMOUNT/work\")\" \ + $ROOT_MOUNT" + fatal "Cound not mount overlay" + fi + ;; + "aufs") + $MOUNT -t aufs i\ + -o "dirs=$ROOT_RWMOUNT=rw:$ROOT_ROMOUNT=ro" \ + aufs $ROOT_MOUNT + ;; + "") + fatal "No overlay filesystem type available" + ;; + esac + + # Move read-only and read-write root file system into the overlay + # file system + mkdir -p $ROOT_MOUNT/$ROOT_ROMOUNT $ROOT_MOUNT/$ROOT_RWMOUNT + $MOUNT -n --move $ROOT_ROMOUNT ${ROOT_MOUNT}/$ROOT_ROMOUNT + $MOUNT -n --move $ROOT_RWMOUNT ${ROOT_MOUNT}/$ROOT_RWMOUNT + + $MOUNT -n --move /proc ${ROOT_MOUNT}/proc + $MOUNT -n --move /sys ${ROOT_MOUNT}/sys + $MOUNT -n --move /dev ${ROOT_MOUNT}/dev + log "overlay: $(grep 'overlay' ${ROOT_MOUNT}/proc/mounts)" + cd $ROOT_MOUNT + if ((DO_STOP)) ; then + fatal "Initramfs Shell mode selected -- bash shell" + fi + + # switch to actual init in the overlay root file system + exec switch_root $ROOT_MOUNT $INIT || + fatal "Couldn't chroot, dropping to shell" +} + +mount_and_boot diff --git a/recipes-core/initrdscripts/initramfs-readonly-rootfs-overlay_1.0.bb b/recipes-core/initrdscripts/initramfs-readonly-rootfs-overlay_1.0.bb new file mode 100644 index 0000000..164d394 --- /dev/null +++ b/recipes-core/initrdscripts/initramfs-readonly-rootfs-overlay_1.0.bb @@ -0,0 +1,8 @@ +require readonly-rootfs-overlay-init-script.inc + +do_install_append() { + install -d ${D}/dev + mknod -m 622 ${D}/dev/console c 5 1 +} + +FILES_${PN} += "/dev" diff --git a/recipes-core/initrdscripts/initscripts-readonly-rootfs-overlay_1.0.bb b/recipes-core/initrdscripts/initscripts-readonly-rootfs-overlay_1.0.bb new file mode 100644 index 0000000..9428356 --- /dev/null +++ b/recipes-core/initrdscripts/initscripts-readonly-rootfs-overlay_1.0.bb @@ -0,0 +1 @@ +require readonly-rootfs-overlay-init-script.inc diff --git a/recipes-core/initrdscripts/readonly-rootfs-overlay-init-script.inc b/recipes-core/initrdscripts/readonly-rootfs-overlay-init-script.inc new file mode 100644 index 0000000..d1b8104 --- /dev/null +++ b/recipes-core/initrdscripts/readonly-rootfs-overlay-init-script.inc @@ -0,0 +1,36 @@ +SUMMARY = "Read only rootfs with overlay init script" +LICENSE = "MIT" +LIC_FILES_CHKSUM = "file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420" +DEPENDS = "virtual/kernel" + +# This was derived from https://github.com/cmhe/meta-readonly-rootfs-overlay + +# script uses bash, findfs, busybox is problematic, so use real fsck, +# and add ext4 utilities in case some one needs to try to recover the +# user_data file system +RDEPENDS_${PN} = " \ + bash \ + util-linux-findfs \ + util-linux-fsck \ + e2fsprogs \ + e2fsprogs-mke2fs \ + e2fsprogs-badblocks \ + e2fsprogs-e2fsck \ + e2fsprogs-tune2fs \ + e2fsprogs-resize2fs \ + " + +SRC_URI = "file://init-readonly-rootfs-overlay-boot.sh" + +S = "${WORKDIR}" + +do_install() { + install -m 0755 ${WORKDIR}/init-readonly-rootfs-overlay-boot.sh ${D}/init + install -d "${D}/run/media/rfs/ro" + install -d "${D}/run/media/rfs/rw" +} + +FILES_${PN} += " /init /run" + +# Due to kernel dependency +PACKAGE_ARCH = "${MACHINE_ARCH}" |