qubes-linux-utils/udev/udev-block-add-change
Marek Marczykowski-Górecki efd9854376
udev/qvm-block: exclude devices used elsewhere
Exclude exclude device if mounted/part of other device, or any of its
partition is used (same definition). Update this state whenever device
or it's partition receives udev event.

Fixes QubesOS/qubes-issues#1600
2016-05-16 11:52:57 +02:00

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#!/bin/bash
shopt -s nullglob
export LC_CTYPE=en_US.UTF-8
NAME=${DEVNAME#/dev/}
DESC="`echo "${ID_MODEL} (${ID_FS_LABEL})" | iconv -f utf8 -t ascii//TRANSLIT`"
SIZE=$[ $(cat /sys/$DEVPATH/size) * 512 ]
MODE=w
QDB_KEY="/qubes-block-devices/$NAME"
xs_remove() {
if [ "$QUBES_EXPOSED" == "1" ]; then
qubesdb-rm "$QDB_KEY/"
qubesdb-write /qubes-block-devices ''
fi
echo QUBES_EXPOSED=0
}
is_used() {
local sys_devpath=$1
# mounted
if fgrep -q $(basename $sys_devpath) /proc/mounts; then
return 0
fi
# part of other device-mapper
if [ -n "`ls -A $sys_devpath/holders 2> /dev/null`" ]; then
return 0
fi
# open device-mapper device
if [ -f "$sys_devpath/dm/name" ] && \
/sbin/dmsetup info "$(cat $sys_devpath/dm/name)" |\
grep -q "^Open count:.*[1-9]"; then
return 0
fi
return 1
}
# update info about parent devices, if any:
if [ -f /sys$DEVPATH/partition ]; then
parent=$(dirname $(readlink -f /sys$DEVPATH))
udevadm trigger \
--property-match=DEVPATH=/$(realpath --relative-to=/sys $parent)
fi
# and underlying devices of device-mapper (if any)
for dev in /sys$DEVPATH/slaves/*; do
udevadm trigger \
--property-match=DEVPATH=/$(realpath --relative-to=/sys $dev)
done
# then take care of this device:
# device itself is already used
if is_used /sys$DEVPATH; then
xs_remove
exit 0
fi
# or one of its partitions is used
for part in /sys$DEVPATH/$NAME*; do
if [ -d $part ]; then
if is_used $part; then
xs_remove
exit 0
fi
fi
done
# or "empty" loop device
if [ "$MAJOR" -eq 7 -a ! -d /sys/$DEVPATH/loop ]; then
xs_remove
exit 0
fi
# ... and temporary devices used during VM startup
if [[ "$NAME" = 'loop'* ]] && \
[[ "`cat /sys/block/${NAME%p*}/loop/backing_file`" = \
'/var/lib/qubes/'*'/volatile.img' ]]; then
xs_remove
exit 0
fi
# Check if device is read-only
if [ "`cat /sys/$DEVPATH/ro`" -eq 1 ]; then
MODE=r
fi
# Special case for CD
if [ "$ID_TYPE" = "cd" ]; then
if [ "$ID_CDROM_MEDIA" != "1" ]; then
# Hide empty cdrom drive
xs_remove
exit 0
fi
MODE=r
fi
# Special description for loop devices
if [ -d /sys/$DEVPATH/loop ]; then
DESC=$(cat /sys/$DEVPATH/loop/backing_file)
fi
# and for device-mapper
if [ -n "$DM_NAME" ]; then
DESC="$DM_NAME"
fi
# The last one is meant to trigger watches
qubesdb-write \
"$QDB_KEY/desc" "$DESC" \
"$QDB_KEY/size" "$SIZE" \
"$QDB_KEY/mode" "$MODE" \
/qubes-block-devices ''
echo QUBES_EXPOSED=1
# Make sure that block backend is loaded
/sbin/modprobe xen-blkback 2> /dev/null || /sbin/modprobe blkbk