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ds2k5
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Joined: 03 Nov 2011
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PostPosted: Thu Nov 03, 2011 5:47 pm    Post subject: cryptsetup + initramfs + lvm2: i dont have /dev/myvg/mylv Reply with quote

hello,
i installed gentoo from: install-amd64-minimal-20111020.iso.
i use cryptsetup and lvm2.
i boot with bootmedia to encrypt the harddisk.
the system boot from media, encrypt the disk, scan for volume groups an activate it, mount the lv´s from the disk
an come up.
but in the bootet system (on harddisk) i dont have /dev/myvg/rootfs, /dev/myvg/homefs, /dev/myvg/usrfs, /dev/myvg/varfs, /dev/myvg/optfs
if i check with vgdisplay and lvdisplay it looks fine.
but lvdisplay give error on eatch lv: /dev/myvg/lvname open failed: no such file or dir
what i did forgot to do that the /dev/myvg/lvnames are created at boottime (after switch/chroot to harddisk)?
thanks
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Hu
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PostPosted: Fri Nov 04, 2011 2:08 am    Post subject: Reply with quote

What is the output of pvscan; vgscan; lvscan; pvs; vgs; lvs?
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ds2k5
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PostPosted: Fri Nov 04, 2011 8:50 am    Post subject: Reply with quote

pvscan
PV /dev/dm-0 VG myvg lvm2 [10.00 GiB / 664.00 MiB free]
Total: 1 [10.00 GiB] / in use: 1 [10.00 GiB] / in no VG: 0 [0 ]

vgscan
Reading all physical volumes. This may take a while...
Found volume group "myvg" using metadata type lvm2

lvscan
ACTIVE '/dev/myvg/boot' [100.00 MiB] inherit
ACTIVE '/dev/myvg/root' [256.00 MiB] inherit
ACTIVE '/dev/myvg/home' [1.00 GiB] inherit
ACTIVE '/dev/myvg/usr' [5.00 GiB] inherit
ACTIVE '/dev/myvg/var' [1.00 GiB] inherit
ACTIVE '/dev/myvg/SWAP' [2.00 GiB] inherit

pvs
PV VG Fmt Attr PSize PFree
/dev/dm-0 myvg lvm2 a- 10.00g 664.00m

vgs
VG #PV #LV #SN Attr VSize VFree
myvg 1 6 0 wz--n- 10.00g 664.00m


lvs
LV VG Attr LSize Origin Snap% Move Log Copy% Convert
SWAP myvg -wi-ao 2.00g
boot myvg -wi-ao 100.00m
home myvg -wi-ao 1.00g
root myvg -wi-ao 256.00m
usr myvg -wi-ao 5.00g
var myvg -wi-ao 1.00g
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lyallp
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PostPosted: Wed Dec 14, 2011 12:10 am    Post subject: Reply with quote

I also use cryptsetup, a non-encrypted partition for /boot, the remaining partition encrypted with LVM inside.
I ended up writing my own initramfs and heavily customising an init script I found, to get the job done.

You will notice the LVM scan, about 3/4 the way down the init script.
To use this, you will need the following to be installed
  • busybox
  • LVM
  • cryptsetup


init script
Code:
#!/bin/sh
################################################################################
# This script is meant to be run as the "init" script of an initramfs, which
# should be a writable filesystem (tmpfs or ramfs, tmpfs preferred).
#
# DO NOT ATTEMT TO RUN THIS IN AN INITRD (ramdisk) without modification
#
################################################################################

PATH="/bin:/sbin:/usr/bin:/usr/sbin"

# Path to directory to mount $ROOTDEV under in initrd
NEWROOT="/new-root"
# Defaults for root= and lvm= parameters in grub.conf
DEFAULT_LVMDEV="/dev/sda2"
DEFAULT_RTDEV="/dev/vg/root"

# Commands used in this initrd script
# Hardcode busybox to ensure availability of commands when /proc isn't
# mounted or symlinks aren't made yet
BBINSTALL="/bin/busybox --install -s"
CAT="/bin/busybox cat"
CHMOD="/bin/busybox chmod"
MOUNT="/bin/busybox mount"
UMOUNT="/bin/busybox umount"
SHELL="/bin/busybox sh"
MKDIR="/bin/busybox mkdir"
GREP="/bin/busybox grep"
AWK="/bin/busybox awk"
SWITCH="/bin/busybox switch_root"
RESUME="/bin/resume"
LOGGER="/bin/busybox logger -t initramfs"

# mdev (busybox symlinks should be usable when using this)
# This will populate /dev with devices.
MDEV="/bin/mdev"

# Kernel command-line (convenience variable)
KCMD="/proc/cmdline"

# Function for dropping to a shell
shell () {
    # $1 = optional reason text for entering shell
    $LOGGER "Rescue shell entered ($1)"
    echo '  Entering rescue shell.'
    echo ''
    if [ "$1" = "" ]
    then
   echo '  Type rootdev root_device to set device to boot.'
   echo '     ex: rootdev /dev/sda1'
    else
   echo "$1"
    fi
    echo '  Exit shell to continue booting.'
   
    $SHELL
}

# Prints out 'Done.' or drops into a shell, for diagnostics
completed () {
   # $1 = return code to test
   # $2 = what failed
    if [ "$1" != "0" ]
    then
   echo "Failed. ($2 - RC=$1)"
   shell "$2"
    else
   echo "Done."
    fi
}

# Create rootdev function
# Used to populate a file /rootdev, which we pre-fill with default values
# but gives us the opportunity to have the 'rescue shell' update the parameter.
echo '#!/bin/sh' > /bin/rootdev
echo 'echo "$1" > /rootdev' >> /bin/rootdev
echo 'exit $?' >> /bin/rootdev
$CHMOD 0755 /bin/rootdev
RDEV="/bin/rootdev"

# Create lvmdev function
# Used to populate a file /lvmdev, which we pre-fill with default values
# but gives us the opportunity to have the 'rescue shell' update the parameter.
echo '#!/bin/sh' > /bin/lvmdev
echo 'echo "$1" > /lvmdev' >> /bin/lvmdev
echo 'exit $?' >> /bin/lvmdev
$CHMOD 0755 /bin/lvmdev
LDEV="/bin/lvmdev"


$LOGGER "Entering initramfs"

# install all busybox symlinks before doing anything else
# /proc still needs to be mounted before the symlinks will work
# otherwise, every symlink points to /proc/this/exe (or something similar)
echo -n "Creating busybox symlinks..."
$BBINSTALL ; completed "$?" "Busybox symlink install failed."

# Ensure that basic directories exist
echo -n "Creating required directories..."
for dir in /proc /sys /dev
do
    [ -d $dir ] || $MKDIR $dir
done
completed "$?" "Failed to create /proc, /sys or /dev"

# Mount /proc, necessary for other mounts
echo -n "Mounting procfs..."
$MOUNT -t proc proc /proc
completed "$?" "Failed to mount procfs"

# Mount /sys, necessary to create the device mapper control device
echo -n "Mounting sysfs..."
$MOUNT -t sysfs sys /sys
completed "$?" "Failed to mount sys"

# Mount tmpfs on /dev and set up /dev/pts
# Run mdev and populate /dev with device nodes
echo "Mounting tmpfs on /dev and running mdev..."
$MOUNT -t tmpfs dev /dev &&
 $MKDIR -p /dev/pts &&
 $MOUNT -t devpts devpts /dev/pts &&
 echo "$MDEV" > /proc/sys/kernel/hotplug &&
 $MDEV -s
completed "$?" "Failed to mount tmpfs and setup /dev/pts"

# Drop to shell if "shell" was passed as kernel param
$GREP -q 'shell' /proc/cmdline && shell "Requested Shell on boot command line."

# Get the args to pass to init, minus key=val pairs
INIT_ARGS="$($AWK '{gsub(/[[:graph:]]+=[[:graph:]]+/,""); print}' $KCMD)"

# remove any initramfs commands from INIT_ARGS
INIT_ARGS="$(echo $INIT_ARGS | $AWK '{gsub(/noresume/,""); print}')"
INIT_ARGS="$(echo $INIT_ARGS | $AWK '{gsub(/shell/,""); print}')"

# Init to run after switch_root to real system
INIT="$($AWK '/.*init=/ {sub(/.*init=/,""); sub(/[ ].*/,""); print}' $KCMD)"
INIT="${INIT:-/sbin/init}"

# Get the default root device if it exists on the kernel command-line
RTDEV="$($AWK '/root=/ {sub(/.*root=/,""); sub(/[ ].*/,""); print}' $KCMD)"
if [ "$RTDEV" = "" ]
then
   RTDEV="${DEFAULT_RTDEV}"
fi
# Get the default lvm partition if it exists on the kernel command-line
LVMDEV="$($AWK '/lvm=/ {sub(/.*lvm=/,""); sub(/[ ].*/,""); print}' $KCMD)"
if [ "$LVMDEV" = "" ]
then
   LVMDEV="${DEFAULT_LVMDEV}"
fi

echo -n "Checking for LVM partition parameter..."
# check if /lvmdev is empty or missing
if [ ! -s /lvmdev ]
then
    # Use our little support function to pre-populate /lvmdev
    $LDEV "$LVMDEV"
    completed "$?" "Failed to make /lvmdev - please create /lvmdev containing the LVM partition, eg /dev/sda2"
fi

echo -n "Checking for Root volume parameter..."
# check if /rootdev is empty or missing
if [ ! -s /rootdev ]
then
    # Use our little support function to pre-populate /rootdev
    $RDEV "$RTDEV"
    completed "$?" "Failed to make /rootdev - please create /rootdev containing the root volume, eg /dev/vg/root"
fi
#
# Give kernel time to finish finding USB devices
#
sleep 2
#
# Enable the Encrypted file system
#
echo "Activating encrypted LVM partition..."
RC=1
while [ "$RC" != "0" ]
do
    LVMDEV="$($CAT /lvmdev)"
    cryptsetup luksOpen ${LVMDEV} vault
    RC="$?"
    if [ "$RC" != "0" ]
    then
        completed "$RC" "Failed to enable decryption on $LVMDEV - use /bin/lvmdev YOUR_ENCRYPTED_LVM_DEVICE to set."
    fi
done

echo -n "Activating LVM Volume Groups..."
RC=1
while [ "$RC" != "0" ]
do
    lvm vgchange --available y --sysinit vg
    RC="$?"
    if [ "$RC" != "0" ]
    then
        completed "$RC" "Failed to activate LVM Volume Groups - please check /lvmdev and try again."
    fi
done


if $GREP -qv 'noresume' /proc/cmdline
then
    # Resume from hibernation, if possible. If there is no image, boot as normal.
    $LOGGER "Attempting resume."
    echo -n "Resuming..."
    $RESUME 2> /dev/null 1> /dev/null
    $LOGGER "Nothing to resume."
    echo "Nothing to resume."
else
    $LOGGER "noresume requested."
fi
$LOGGER "Booting."
echo "Booting..."

# Mount the root partition
# ensure that the directory we mount to exists
echo "Mounting new root filesystem"
SUCCESS=0
[ -d $NEWROOT ] || $MKDIR $NEWROOT
while [ "${SUCCESS}" != "1" ]
do
    ROOTDEV="$($CAT /rootdev)"

    if ! $MOUNT -t xfs -o ro "$ROOTDEV" "$NEWROOT"
    then
        echo ""
        echo "Couldn't mount root FS read-only!"
        echo "Tell me your root device by doing:"
        echo "rootdev YOUR_ROOT_DEVICE"
        shell "Couldn't mount root FS read-only!. execute '/rootdev YOUR_ROOT_DEVICE; exit 0'"
   set -x
    else
        SUCCESS=1
    fi
done

if [ ! -e "$NEWROOT/$INIT" ]
then
    shell "$ROOTDEV successfully mounted but no $INIT found!"
fi

echo -n "Resetting kernel hotplugging..."
echo "" > /proc/sys/kernel/hotplug
completed "$?" "Resetting kernel hotplugging"

echo -n "Unmounting /sys..."
$UMOUNT /sys
completed "$?" "Unmounting /sys"

# Clean out /dev/vg so that it is populated properly by the main system init.
echo -n "Unmounting /dev..."
$UMOUNT /dev/pts &&
rm -f /dev/vg/* &&
rmdir /dev/vg &&
$UMOUNT /dev
completed "$?" "Unmounting /dev"

echo -n "Unmounting /proc..."
$UMOUNT /proc
completed "$?" "Unmounting /proc"

$LOGGER "Completed pre-boot."

# Change to the new root partition and execute /sbin/init
echo "Executing switch_root and spawning init"
if ! exec $SWITCH "$NEWROOT" "$INIT" $INIT_ARGS
then
    echo ""
    echo "Couldn't switch_root ($SWITCH $NEWROOT $INIT $INIT_ARGS)"
    $MOUNT -t proc proc /proc
    exec $SHELL
fi

README
Code:
Critical that init contains #!/bin/sh as the first line, or it won't run.


Problems during boot (you are in the rescue shell(s))
=====================================================
The following 2 files must exist.
    /lvmdev   - this should contain the partition in which LVM is configured
          eg. /dev/sda2
    /rootdev   - this should contain the volume group on which the root filesystem is.
          eg. /dev/vg/root

2 convenience functions will be available as /bin/lvmdev and /bin/rootdev, which take
a single parameter and populate the corresponding file with that value. You could simply
do an "echo /dev/vg/root > /lvmdev" if you wanted to.


To chroot into this initramfs to test
=====================================
****************************************
DO NOT RUN "busybox --install -s" unless you are IN A CHROOT PRISON.
YOU WILL DESTROY YOUR SYSTEM.
****************************************

mount -t proc none /tmp/initramfs/proc
mount -o bind /dev /tmp/initramfs/dev
chroot /tmp/initramfs /bin/sh

Don't forget to umount them after exiting the chroot prison

umount /tmp/initramfs/proc
umount /tmp/initramfs/dev

The script expects two kernel parameters in the grub.conf entry.

lvm=/dev/partition root=/dev/vg/partition

LVM Parameters
==============
lvm=/dev/sda3

The partition in which LVM is configured.
In this example, /dev/sda3 is configured as an Encrypted partition, using
# cryptsetup luksOpen /dev/sda3 vault
which will prompt for a password.
This will decrypt the partition such that LVM can find it using
# vgchange -ay vg



Kernel Parameters
=================
root=/dev/vg/root

The parition which contains the root filesystem.
In this case, it's a LVM filesystem, which is living on an encrypted parition.

Disabling Resume (in case of broken resume functionality)
=========================================================
noresume

This prevents the use of the 'resume' capability.



Refresh the files in this archive if the following packages have updates
 * sys-fs/cryptsetup
 * sys-fs/lvm2
 * sys-apps/busybox
Use the script "UpdateFilesInArchive.sh"
This will copy files into the initramfs directory and recreate the initramfs.


Re-creating the initramfs without updating file versions.
=========================================================
# cd /boot/initramfs
# find . | cpio --quiet -o -H newc | gzip -9 > /boot/initramfs_gentoo_crypt_cpio.gz

Build/update the initramfs script
Code:
#!/bin/bash

if [ "${PWD}" != "/boot/initramfs" ]
then
    echo "No way will I run this outside of /boot/initramfs."
    exit 1
fi
cp /bin/busybox /sbin/cryptsetup /sbin/mdadm /usr/lib64/suspend/resume /boot/initramfs/bin || exit 1
cp /sbin/lvm.static /boot/initramfs/bin/lvm              || exit 1
cp /etc/suspend.conf /boot/initramfs/etc/suspend.conf           || exit 1

echo "/boot/initramfs updated with files from home system."

cd /boot/initramfs || exit 1
find . | cpio --quiet -o -H newc | gzip -9 > /boot/initramfs_gentoo_crypt_cpio.gz || exit 1

echo "/boot/initramfs_gentoo_crypt_cpio.gz has been updated."


Sample Grub entry
Code:
efault 0
timeout 10
#splashimage=(hd0,0)/boot/grub/splash.xpm.gz

# 3.0.6 kernel

# Tested with hi res console
# Tested with kernel power regression workaround
#  http://www.phoronix.com/scan.php?page=article&item=linux_2638_aspm&num=2
title Gentoo Linux 3.0.6 1920x1080-32@75
root (hd0,0)
kernel /boot/vmlinuz-3.0.6-gentoo root=/dev/vg/root lvm=/dev/sda2 video=uvesafb:1920x1080-32@75,mtrr:3,ywrap fbcon=scrollback:64K pcie_aspm=force
initrd /boot/initramfs_gentoo_crypt_cpio.gz

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cach0rr0
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Posts: 4123
Location: Houston, Republic of Texas

PostPosted: Wed Dec 14, 2011 10:29 am    Post subject: Reply with quote

yikes. that init is huge
I have a tiny one with things hard-coded

Code:

#!/bin/busybox sh

rescue_shell() {
        echo "Something went wrong. Dropping you to a shell."
                busybox --install -s
        exec /bin/sh
}

mount -t proc none /proc
mount -t sysfs none /sys
mount -t devtmpfs none /dev

cryptsetup -T 5 luksOpen /dev/sda2 root
#you could put your LVM stuff here, before the mounting of root
mount -o ro /dev/mapper/root /mnt/root || rescue_shell

umount /proc
umount /sys
umount /dev

exec switch_root /mnt/root /sbin/init

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lyallp
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PostPosted: Fri Dec 16, 2011 11:14 pm    Post subject: Reply with quote

It is huge, but it supports LVM, including root on LVM, suspend/resume and allows for screwups in kernel parameters (which got used during development).
It also has error checking ;)
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