Implement encrypted cdrom ejection

This allows the cdrom to be copied onto the outer filesystem (mounted in
/outerfs) without storing unencrypted gpg keys there.

e.g.:

  samizdat-eject.sh /outerfs/samizdat.iso

This was necessary because the other method probably causes btrfs deadlocks.

We do end up copying data twice this way (or three times, probably --
if the ISO is saved), but not _from the cdrom_.  And we get to eject
immediately after the first copy.  Future copies will be from the hard
drive.  Not too bad.

2 files changed, 70 insertions, 2 deletions

diff --git a/old-school/lvm-create.sh b/old-school/lvm-create.sh
index ce0862e..916b888 100644
--- a/old-school/lvm-create.sh
+++ b/old-school/lvm-create.sh
@@ -53,12 +53,35 @@ init_samizdat()
 
   btrfs device add "$blockdev" /root || return
   mount -o rw,remount /root || return
+  samizdat_movemounts "$imgfile"
 
   initialize_root_filesystem || return
 
   bootdone root-mounted
 }
 
+samizdat_movemounts()
+{
+    local imgfile="$1" mountpoint
+
+    mountpoint=$(mountpoint_of "$imgfile") || return
+    mkdir /root/cdrom /root/outerfs
+    mount -o move /cdrom /root/cdrom
+    mount -o move "$mountpoint" /root/outerfs
+    mkdir /run/initramfs/samizdat
+    mv /var/log /run/initramfs/samizdat/log
+}
+
+mountpoint_of()
+{
+    local f="$1"
+    while ! mountpoint -q "$f"; do
+        f=$(dirname "$f")
+        [ "$f" != '.' ] || return 1
+    done
+    printf '%s\n' "$f"
+}
+
 initialize_root_filesystem()
 {
     rm -r /root/root
@@ -117,7 +140,7 @@ filesystem_incomplete()
 open_samizdat()
 {
   open_samizdat_blockdev "$@" || return
-  local blockdev=/dev/mapper/samizdatcrypt fs
+  local blockdev=/dev/mapper/samizdatcrypt imgfile="$1" fs
 
   # For this part, we don't necessarily need the cdrom.
   # Unfortunately the init_gpg code is still getting the GPG key there.
@@ -127,6 +150,7 @@ open_samizdat()
   modprobe btrfs || return
   btrfs device scan || return
   mount -t btrfs -o subvol=ROOT "$blockdev" /root || return
+  samizdat_movemounts "$imgfile"
   LoSetup -D
   bootdone root-mounted
 }
diff --git a/old-school/mdadm-dup.sh b/old-school/mdadm-dup.sh
index 16e3dfd..fe18e92 100644
--- a/old-school/mdadm-dup.sh
+++ b/old-school/mdadm-dup.sh
@@ -116,7 +116,51 @@ mdadm_subdevices()
     mdadm -D "$md_dev" -Y | sed -ne 's/^MD_DEVICE_.*_DEV=//p'
 }
 
-mdadm_copy_eject() # NOT INITRD; uses non-busybox "losetup"
+cryptsetup_temp()
+{
+    local sectors="$1" cryptname="$2" temp_file="$3" parms=$- secret
+    set +x
+    # Add 4096 sectors for LUKS header
+    truncate -s $(((sectors + 4096) * 512)) "$temp_file" || return
+    cleartext_dev=$(LoSetup -f --show "$temp_file")      || return
+    secret="$(head -c256 /dev/urandom)"                  || return
+    printf %s "$secret" |
+        cryptsetup luksFormat "$cleartext_dev" - || return
+    printf %s "$secret" |
+        cryptsetup --key-file - luksOpen "$cleartext_dev" "$cryptname" || return
+    unset secret
+    set $parms
+
+    wait_for_dm_device /dev/mapper/"$cryptname"
+    echo /dev/mapper/"$cryptname"
+}
+
+mdadm_copy_eject_crypt()
+{
+    local md_dev="$1" temp_file="$2"
+
+    [ -b "$md_dev" ]                                  || return
+    [ ! -e "$temp_file" ]                             || return
+
+    local output_dev sectors
+
+    old_subdev=$(mdadm_subdevices "$md_dev"|head -n1) || return
+    [ -b "$old_subdev" ]                              || return
+    # TODO: truncate to the ISO fs size if the device is larger
+    sectors=$(blockdev --getsz "$md_dev")             || return
+
+    output_dev=$(cryptsetup_temp "$sectors" samizdatiso "$temp_file") || return
+
+    mdadm "$md_dev" --add "$output_dev"               || return
+    mdadm "$md_dev" --grow -n2                        || return
+
+    mdadm_wait_remove "$md_dev" "$old_subdev"         || return
+
+    mdadm "$md_dev" --grow -n1 --force                || return
+    dm_snapshot_teardown "$old_subdev"
+}
+
+mdadm_copy_eject()
 {
     local md_dev="$1" output_file="$2"