SOURCES: cryptsetup-luks-initramfs-README (NEW), cryptsetup-luks-initramfs-...
baggins
baggins at pld-linux.org
Thu Feb 26 15:25:43 CET 2009
Author: baggins Date: Thu Feb 26 14:25:43 2009 GMT
Module: SOURCES Tag: HEAD
---- Log message:
- support for initramfs-tools
---- Files affected:
SOURCES:
cryptsetup-luks-initramfs-README (NONE -> 1.1) (NEW), cryptsetup-luks-initramfs-passdev-hook (NONE -> 1.1) (NEW), cryptsetup-luks-initramfs-root-conf (NONE -> 1.1) (NEW), cryptsetup-luks-initramfs-root-hook (NONE -> 1.1) (NEW), cryptsetup-luks-initramfs-root-script (NONE -> 1.1) (NEW), dmraid-initramfs-hook (NONE -> 1.1) (NEW), dmraid-initramfs-local-top (NONE -> 1.1) (NEW), lvm2-initramfs-hook (NONE -> 1.1) (NEW), lvm2-initramfs-local-top (NONE -> 1.1) (NEW), mdadm-initramfs-hook (NONE -> 1.1) (NEW), mdadm-initramfs-local-top (NONE -> 1.1) (NEW), multipath-tools-initramfs-hooks (NONE -> 1.1) (NEW), multipath-tools-initramfs-local-top (NONE -> 1.1) (NEW), openct-initramfs-hook (NONE -> 1.1) (NEW), opensc-initramfs-README (NONE -> 1.1) (NEW), opensc-initramfs-hook (NONE -> 1.1) (NEW), opensc-initramfs-local-bottom (NONE -> 1.1) (NEW), opensc-initramfs-local-top (NONE -> 1.1) (NEW)
---- Diffs:
================================================================
Index: SOURCES/cryptsetup-luks-initramfs-README
diff -u /dev/null SOURCES/cryptsetup-luks-initramfs-README:1.1
--- /dev/null Thu Feb 26 15:25:44 2009
+++ SOURCES/cryptsetup-luks-initramfs-README Thu Feb 26 15:25:30 2009
@@ -0,0 +1,194 @@
+1. Introduction
+---------------
+Kernels more recent than 2.6.12 have dropped support for devfs, which
+means that initrd-tools can no longer be used to boot into an encrypted
+root partition. Instead, a similar functionality has been developed for
+use with an initramfs-image.
+
+
+2. A fresh installation
+-----------------------
+If you plan to perform a completely new installation of Debian onto a
+machine and to do so using an encrypted root partition, you might want
+to consider using a version of Debian Installer with partman-crypto
+(see http://wiki.debian.org/DebianInstaller/PartmanCrypto).
+
+The installation will then take care of all the details and perform the
+necessary configuration for you, meaning that you should not have to
+read the rest of this document to get a machine with an encrypted
+root fs up and running.
+
+However, if you are not planning to perform a new installation from scratch,
+the following information might be useful to you.
+
+
+3. Requirements
+---------------
+In order to boot from an encrypted root fs, you need an initramfs-image
+which includes the necessary kernel modules and scripts to setup
+the root device after the kernel has been initialized, but before the rest
+of the operating system is booted.
+
+To do so, you need two partitions:
+- an unencrypted /boot partition
+- an encrypted / partition
+
+In addition, you need to have initramfs-tools installed.
+
+NOTE: You should make sure that your swap partition is either encrypted, or
+that you are using a swap file on an encrypted partition, as crypto keys and
+other sensitive information might otherwise be written out to the swap
+partition in unencrypted form.
+
+
+4. Setup (regular dm-crypt)
+---------------------------
+First of all, you must edit /etc/crypttab and add a line describing your
+root device, for example:
+
+ cryptroot /dev/hda2 none cipher=aes-cbc-essiv:sha256,size=256,hash=sha256
+
+This will allow cryptsetup to create /dev/mapper/cryptroot from the
+encrypted partition /dev/hda2 during boot.
+
+In addition, you must also make sure that the root device is listed in
+/etc/fstab, for example:
+
+ /dev/mapper/cryptroot / ext3 defaults 0 1
+
+This will allow the initramfs support scripts to know which of the devices
+in the crypttab that is the root device.
+
+After doing these changes, you should regenerate the initramfs by running
+"initramfs-update -u", then make sure that your boot loader is configured
+to feed the initramfs to the kernel when booting. The kernel root argument
+should also be changed to /dev/mapper/cryptroot.
+
+Now, reboot the machine, and if everything is correctly configured, you
+should be given a prompt to type in the passphrase for the encrypted
+root partition before the boot can continue.
+
+NOTE: the initramfs scripts default to using the sha256 hash function while
+the plain cryptsetup binary defaults to using the ripemd160 hash function.
+In order to ensure that the crypto setup works in a consistant manner, you
+should make sure that the hash function is specified in the /etc/crypttab file
+if you are using regular dm-crypt (with LUKS the hash function to use is stored
+in the LUKS header).
+
+
+5. Setup (using LUKS)
+---------------------
+If you are using the LUKS feature of cryptsetup, the above setup recipe should
+still apply, but since most options can be derived from the information stored
+in the LUKS header on-disk, the line to add to /etc/crypttab should look
+something like this:
+
+ cryptroot /dev/sda2 none luks
+
+
+6. Exotic key types
+-------------------
+The above examples assume that you use a regular passphrase as the key to the
+encrypted filesystem. However, if you wish to make use of more complex setups
+(such as root-key-on-usb-memory), you can create a script which does all the
+steps necessary to retrieve the key and then prints it to stdout.
+
+Then add a keyscript=/path/to/your/script.sh to the options (fourth column) in
+the above mentioned /etc/crypttab line, so that it looks something like this:
+
+ cryptroot /dev/sda2 none luks,keyscript=/usr/local/sbin/cryptkey
+
+Next, regenerate your initramfs image. This will copy the script into the
+initramfs image under the /keyscripts/ directory.
+
+NOTE: there is a limited set of tools available when the script is executing
+as part of the initramfs bootup, you have to make sure that you do not use
+any tools which are not available or your script, and therefore boot, will
+fail.
+
+
+7. "cryptopts" boot argument
+----------------------------
+In general, you should use the above approach with a line describing your
+root partition in /etc/crypttab and /etc/fstab. However, if for some reason
+you wish to override the settings that are derived from these files and
+stored in the initramfs image, you can use the "cryptopts" boot argument
+(this *only* works for the root partition).
+
+The format of cryptopts is:
+cryptopts=<opt1>=<value1>,<opt2>=<value2>...
+
+Beside the "hash", "size", "cipher" and "lvm" options that correspond to the
+same options in the fourth field of /etc/crypttab, the options "target",
+"source" and "key" are also supported. They correspond to the first, second
+and third field of /etc/crypttab, respectively. See the crypttab man page
+for further details.
+
+Several "cryptopts" boot arguments can also be specified in case more than
+one mapping needs to be setup in the initramfs stage of the boot.
+
+Example boot arguments:
+root=/dev/mapper/crypt0 cryptopts=target=crypt0,source=/dev/hda1,cipher=twofish
+
+8. Resume device support
+------------------------
+The initramfs scripts will also try to automatically determine the devices,
+if any, that are used for software suspend (swsusp, suspend2 or uswsusp) and
+to set them up during the initramfs stage in order to allow suspend and resume
+in combination with encryption to keep the resume image safe from potential
+attackers.
+
+If your resume device and your root partition use two different cryptsetup
+mappings, you might want to use the "decrypt_derived" keyscript as described
+below.
+
+9. The "decrypt_derived" keyscript
+----------------------------------
+Assume that you have two entries in /etc/crypttab:
+
+cryptroot /dev/hda1 none luks
+cryptswap /dev/hda2 none luks
+
+If cryptswap is used as your suspend/resume device, you'd normally need to
+enter two different passphrases during the boot, but the "decrypt_derived"
+script can generate the key for the second mapping using a hash of the key
+for the first mapping.
+
+In short, you'll need to do something like the following to take advantage
+of the decrypt_derived script:
+
+1) swapoff -a
+2) cryptsetup luksClose cryptswap
+3) edit /etc/crypttab and change the cryptswap line to e.g.:
+cryptswap /dev/hda2 cryptroot cipher=aes-cbc-essiv:sha256,size=256,hash=sha256,keyscript=/lib/cryptsetup/scripts/decrypt_derived,swap
+4) /etc/init.d/cryptdisks start
+5) Make sure that /dev/mapper/cryptswap has been created
+6) swapon -a
+7) (optional) update-initramfs -u
+
+After you've followed the above steps, your swap device should be setup
+automatically after the root device has been setup during the boot stage.
+
+Note: If you don't use suspend device support, it's better to use completely
+random keys for your encrypted swap device. See the section '2. Encrypted
+swap partition(s)' in /usr/share/doc/cryptsetup/README.Debian for information
+on how to setup this.
+
+10. The "passdev" keyscript
+----------------------------
+If you have a keyfile on a removable device (e.g. a USB-key), you can use the
+passdev keyscript. It will wait for the device to appear, mount it read-only,
+read the key and then unmount the device.
+
+The "key" part of /etc/crypttab will be interpreted as <device>:<path>, it is
+strongly recommended that you use one of the persistent device names from
+/dev/disk/*, e.g. /dev/disk/by-label/myusbkey.
+
+This is an example of a suitable line in cryptsetup:
+cryptroot /dev/hda2 /dev/disk/by-label/myusbkey:/keys/root.key cipher=aes-cbc-essiv:sha256,size=256,hash=plain,keyscript=/lib/cryptsetup/scripts/passdev
+
+The above line would cause the boot to pause until /dev/disk/by-label/myusbkey
+appears in the fs, then mount that device and use the file /keys/root.key
+on the device as the key (without any hashing) as the key for the fs.
+
+-- David Härdeman <david at hardeman.nu>
================================================================
Index: SOURCES/cryptsetup-luks-initramfs-passdev-hook
diff -u /dev/null SOURCES/cryptsetup-luks-initramfs-passdev-hook:1.1
--- /dev/null Thu Feb 26 15:25:44 2009
+++ SOURCES/cryptsetup-luks-initramfs-passdev-hook Thu Feb 26 15:25:30 2009
@@ -0,0 +1,40 @@
+#!/bin/sh
+
+set -e
+
+PREREQ="cryptroot"
+
+prereqs()
+{
+ echo "$PREREQ"
+}
+
+case $1 in
+prereqs)
+ prereqs
+ exit 0
+ ;;
+esac
+
+. /usr/share/initramfs-tools/hook-functions
+
+# Hooks for adding filesystem modules to the initramfs when the passdev
+# keyscript is used
+
+# Check whether the passdev script has been included
+if [ ! -x "${DESTDIR}/keyscripts/passdev" ]; then
+ exit 0
+fi
+
+# The filesystem type of the removable device is probed at boot-time, so
+# we add a generous list of filesystems to include. This also helps with
+# recovery situation as including e.g. the vfat module might help a user
+# who needs to create a new cryptkey (using a backup of a keyfile) on
+# a windows-machine for example.
+
+# This list needs to be kept in sync with the one defined in passdev.c
+for fs in ext3 ext2 vfat reiserfs xfs isofs udf; do
+ manual_add_modules "$fs" > /dev/null 2>&1 || true
+done
+exit 0
+
================================================================
Index: SOURCES/cryptsetup-luks-initramfs-root-conf
diff -u /dev/null SOURCES/cryptsetup-luks-initramfs-root-conf:1.1
--- /dev/null Thu Feb 26 15:25:45 2009
+++ SOURCES/cryptsetup-luks-initramfs-root-conf Thu Feb 26 15:25:30 2009
@@ -0,0 +1,6 @@
+# This will setup non-us keyboards in early userspace,
+# necessary for punching in passphrases.
+KEYMAP=y
+
+# force busybox on initramfs
+BUSYBOX=y
================================================================
Index: SOURCES/cryptsetup-luks-initramfs-root-hook
diff -u /dev/null SOURCES/cryptsetup-luks-initramfs-root-hook:1.1
--- /dev/null Thu Feb 26 15:25:45 2009
+++ SOURCES/cryptsetup-luks-initramfs-root-hook Thu Feb 26 15:25:31 2009
@@ -0,0 +1,487 @@
+#!/bin/sh
+
+PREREQ=""
+
+prereqs()
+{
+ echo "$PREREQ"
+}
+
+case $1 in
+prereqs)
+ prereqs
+ exit 0
+ ;;
+esac
+
+. /usr/share/initramfs-tools/hook-functions
+
+get_root_device() {
+ local device mount type options dump pass
+
+ if [ ! -r /etc/fstab ]; then
+ return 1
+ fi
+
+ grep '^[^#]' /etc/fstab | \
+ while read device mount type options dump pass; do
+ if [ "$mount" = "/" ]; then
+ echo "$device"
+ return
+ fi
+ done
+}
+
+get_resume_devices() {
+ local device opt count dupe candidates devices
+ candidates=""
+
+ # First, get a list of potential resume devices
+
+ # uswsusp
+ if [ -e /etc/uswsusp.conf ]; then
+ device=$(sed -rn 's/^resume device[[:space:]]*[:=][[:space:]]*// p' /etc/uswsusp.conf)
+ if [ -n "$device" ]; then
+ candidates="$candidates $device"
+ fi
+ fi
+
+ # uswsusp - again...
+ if [ -e /etc/suspend.conf ]; then
+ device=$(sed -rn 's/^resume device[[:space:]]*[:=][[:space:]]*// p' /etc/suspend.conf)
+ if [ -n "$device" ]; then
+ candidates="$candidates $device"
+ fi
+ fi
+
+ # regular swsusp
+ for opt in $(cat /proc/cmdline); do
+ case $opt in
+ resume=*)
+ device="${opt#resume=}"
+ candidates="$candidates $device"
+ ;;
+ esac
+ done
+
+ # initramfs-tools
+ if [ -e /etc/initramfs-tools/conf.d/resume ]; then
+ device=$(sed -rn 's/^RESUME[[:space:]]*=[[:space:]]*// p' /etc/initramfs-tools/conf.d/resume)
+ if [ -n "$device" ]; then
+ candidates="$candidates $device"
+ fi
+ fi
+
+ # Now check the sanity of all candidates
+ devices=""
+ count=0
+ for device in $candidates; do
+ # Weed out clever defaults
+ if [ "$device" = "<path_to_resume_device_file>" ]; then
+ continue
+ fi
+
+ # Weed out duplicates
+ dupe=0
+ for opt in $devices; do
+ if [ "$device" = "$opt" ]; then
+ dupe=1
+ fi
+ done
+ if [ $dupe -eq 1 ]; then
+ continue
+ fi
+
+ # This device seems ok
+ devices="$devices $device"
+ count=$(( $count + 1 ))
+ done
+
+ if [ $count -gt 1 ]; then
+ echo "cryptsetup: WARNING: found more than one resume device candidate:" >&2
+ for device in $devices; do
+ echo " $device" >&2
+ done
+ fi
+
+ if [ $count -gt 0 ]; then
+ echo $devices
+ fi
+
+ return 0
+}
+
+node_is_in_crypttab() {
+ local node
+ node="$1"
+
+ grep -q ^$node /etc/crypttab
+ return $?
+}
+
+get_lvm_deps() {
+ local node deps maj min depnode
+ node="$1"
+
+ if [ -z $node ]; then
+ echo "cryptsetup: WARNING: get_lvm_deps - invalid arguments" >&2
+ return 1
+ fi
+
+ if ! deps=$(dmsetup deps "$node" 2> /dev/null | sed 's/[^:]*: *//;s/[ (]//g;s/)/ /g'); then
+ echo "cryptsetup: WARNING: failed to find deps for $node" >&2
+ return 1
+ fi
+
+ # We should now have a list of major,minor pairs, e.g. "3,2 3,3"
+ for dep in $deps; do
+ maj=${dep%,*}
+ min=${dep#*,}
+ depnode=$(dmsetup ls | sed -n "s/\\([^ ]*\\) *($maj, $min)/\\1/p" | sed -e "s/[ \t]*$//")
+ if [ -z "$depnode" ]; then
+ continue
+ fi
+ if [ "$(dmsetup table "$depnode" 2> /dev/null | cut -d' ' -f3)" != "crypt" ]; then
+ get_lvm_deps "$depnode"
+ continue
+ fi
+ echo "$depnode"
+ done
+
+ return 0
+}
+
+get_device_opts() {
+ local target source link extraopts rootopts opt
+ target="$1"
+ extraopts="$2"
+ KEYSCRIPT=""
+ OPTIONS=""
+
+ if [ -z "$target" ]; then
+ echo "cryptsetup: WARNING: get_device_opts - invalid arguments" >&2
+ return 1
+ fi
+
+ opt=$( grep ^$target /etc/crypttab | head -1 | sed 's/[[:space:]]\+/ /g' )
+ source=$( echo $opt | cut -d " " -f2 )
+ key=$( echo $opt | cut -d " " -f3 )
+ rootopts=$( echo $opt | cut -d " " -f4- )
+
+ if [ -z "$opt" ] || [ -z "$source" ] || [ -z "$key" ] || [ -z "$rootopts" ]; then
+ echo "cryptsetup: WARNING: invalid line in /etc/crypttab - $opt" >&2
+ return 1
+ fi
+
+ # Sanity checks for $source
+ if [ -h "$source" ]; then
+ link=$(readlink -nqe "$source")
+ if [ -z "$link" ]; then
+ echo "cryptsetup: WARNING: $source is a dangling symlink" >&2
+ return 1
+ fi
+
+ if [ "$link" != "${link#/dev/mapper/}" ]; then
+ echo "cryptsetup: NOTE: using $link instead of $source for $target" >&2
+ source="$link"
+ fi
+ fi
+
+ # Sanity checks for $key
+ if [ "$key" = "/dev/random" ] || [ "$key" = "/dev/urandom" ]; then
+ echo "cryptsetup: WARNING: target $target has a random key, skipped" >&2
+ return 1
+ fi
+
+ if [ -n "$extraopts" ]; then
+ rootopts="$extraopts,$rootopts"
+ fi
+
+ # We have all the basic options, let's go trough them
+ OPTIONS="target=$target,source=$source,key=$key"
+ local IFS=", "
+ unset HASH_FOUND
+ unset LUKS_FOUND
+ for opt in $rootopts; do
+ case $opt in
+ cipher=*)
+ OPTIONS="$OPTIONS,$opt"
+ ;;
+ hash=*)
+ OPTIONS="$OPTIONS,$opt"
+ HASH_FOUND=1
+ ;;
+ size=*)
+ OPTIONS="$OPTIONS,$opt"
+ ;;
+ lvm=*)
+ OPTIONS="$OPTIONS,$opt"
+ ;;
+ keyscript=*)
+ opt=${opt#keyscript=}
+ if [ ! -x "/lib/cryptsetup/scripts/$opt" ] && [ ! -x "$opt" ]; then
+ echo "cryptsetup: WARNING: target $target has an invalid keyscript, skipped" >&2
+ return 1
+ fi
+ KEYSCRIPT="$opt"
+ OPTIONS="$OPTIONS,keyscript=/keyscripts/$(basename "$opt")"
+ ;;
+ tries=*)
+ OPTIONS="$OPTIONS,$opt"
+ ;;
+ luks)
+ LUKS_FOUND=1
+ ;;
+ *)
+ # Presumably a non-supported option
+ ;;
+ esac
+ done
+
+ # Warn for missing hash option, unless we have a LUKS partition
+ if [ -z "$HASH_FOUND" ] && [ -z "$LUKS_FOUND" ]; then
+ echo "WARNING: Option hash missing in crypttab for target $target, assuming ripemd160." >&2
+ echo " If this is wrong, this initramfs image will not boot." >&2
+ echo " Please read /usr/share/doc/cryptsetup/README.initramfs.gz and add" >&2
+ echo " the correct hash option to your /etc/crypttab." >&2
+ fi
+
+ # If keyscript is set, the "key" is just an argument to the script
+ if [ "$key" != "none" ] && [ -z "$KEYSCRIPT" ]; then
+ echo "cryptsetup: WARNING: target $target uses a key file, skipped" >&2
+ return 1
+ fi
+}
+
+get_device_modules() {
+ local node value cipher blockcipher ivhash
+ node="$1"
+
+ # Check the ciphers used by the active root mapping
+ value=$(dmsetup table "$node" | cut -d " " -f4)
+ cipher=$(echo "$value" | cut -d ":" -f1 | cut -d "-" -f1)
+ blockcipher=$(echo "$value" | cut -d ":" -f1 | cut -d "-" -f2)
+ ivhash=$(echo "$value" | cut -d ":" -s -f2)
+
+ if [ -n "$cipher" ]; then
+ echo "$cipher"
+ else
+ return 1
+ fi
+
+ if [ -n "$blockcipher" ] && [ "$blockcipher" != "plain" ]; then
+ echo "$blockcipher"
+ fi
+
+ if [ -n "$ivhash" ] && [ "$ivhash" != "plain" ]; then
+ echo "$ivhash"
+ fi
+ return 0
+}
+
+canonical_device() {
+ local dev altdev
+ dev="$1"
+
+ altdev="${dev#LABEL=}"
+ if [ "$altdev" != "$dev" ]; then
+ dev="/dev/disk/by-label/$altdev"
+ fi
+
+ altdev="${dev#UUID=}"
+ if [ "$altdev" != "$dev" ]; then
+ dev="/dev/disk/by-uuid/$altdev"
+ fi
+
+ if [ -h "$dev" ]; then
+ dev=$(readlink -e "$dev")
+ fi
+
+ altdev="${dev#/dev/mapper/}"
+ if [ "$altdev" != "$dev" ]; then
+ echo "$altdev"
+ return 0
+ fi
+
+ return 1
+}
+
+add_device() {
+ local node nodes opts lastopts i count
+ nodes="$1"
+ opts="" # Applied to all nodes
+ lastopts="" # Applied to last node
+
+ if [ -z "$nodes" ]; then
+ return 0
+ fi
+
+ # Check that it is a node under /dev/mapper/
+ nodes=$(canonical_device "$nodes") || return 0
+
+ # Can we find this node in crypttab
+ if ! node_is_in_crypttab "$nodes"; then
+ # dm node but not in crypttab, is it a lvm device backed by dm-crypt nodes?
+ lvmnodes=$(get_lvm_deps "$nodes") || return 1
+
+ # not backed by any dm-crypt nodes; stop here
+ if [ -z "$lvmnodes" ]; then
+ return 0
+ fi
+
+ # It is a lvm device!
+ lastopts="lvm=$nodes"
<<Diff was trimmed, longer than 597 lines>>
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