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-rw-r--r--debian/initramfs/cryptroot-unlock196
1 files changed, 196 insertions, 0 deletions
diff --git a/debian/initramfs/cryptroot-unlock b/debian/initramfs/cryptroot-unlock
new file mode 100644
index 0000000..dbc2ad0
--- /dev/null
+++ b/debian/initramfs/cryptroot-unlock
@@ -0,0 +1,196 @@
+#!/bin/busybox ash
+
+# Remotely unlock encrypted volumes.
+#
+# Copyright © 2015-2018 Guilhem Moulin <guilhem@debian.org>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+set -ue
+PATH=/sbin:/bin
+
+TIMEOUT=10
+PASSFIFO=/lib/cryptsetup/passfifo
+ASKPASS=/lib/cryptsetup/askpass
+UNLOCK_ALL=n
+
+[ -f /lib/cryptsetup/functions ] || return 0
+. /lib/cryptsetup/functions
+TABFILE="/cryptroot/crypttab"
+unset -v IFS
+
+if [ ! -f "$TABFILE" ] || [ "$TABFILE" -ot "/proc/1" ]; then
+ # Too early, init-top/cryptroot hasn't finished yet
+ echo "Try again later" >&2
+ exit 1
+fi
+
+# Print the list of PIDs the executed command of which is $exe.
+pgrep_exe() {
+ local exe pid
+ exe="$(readlink -f -- "$1" 2>/dev/null)" && [ -f "$exe" ] || return 0
+ ps -eo pid= | while read pid; do
+ [ "$(readlink -f "/proc/$pid/exe")" != "$exe" ] || printf '%d\n' "$pid"
+ done
+}
+
+# Return 0 if $pid has a file descriptor pointing to $name, and 1
+# otherwise.
+in_fds() {
+ local pid="$1" name fd
+ name="$(readlink -f -- "$2" 2>/dev/null)" && [ -e "$name" ] || return 1
+ for fd in $(find "/proc/$pid/fd" -type l); do
+ [ "$(readlink -f "$fd")" != "$name" ] || return 0
+ done
+ return 1
+}
+
+# Print the PID of the askpass process with a file descriptor opened to
+# /lib/cryptsetup/passfifo.
+get_askpass_pid() {
+ local pid
+ for pid in $(pgrep_exe "$ASKPASS"); do
+ if in_fds "$pid" "$PASSFIFO"; then
+ echo "$pid"
+ return 0
+ fi
+ done
+ return 1
+}
+
+# Print the number of configured crypt devices that have not been unlocked yet.
+count_locked_devices() {
+ local COUNT=0
+ crypttab_foreach_entry count_locked_devices_callback
+ printf '%d\n' "$COUNT"
+}
+count_locked_devices_callback() {
+ dm_blkdevname "$CRYPTTAB_NAME" >/dev/null || COUNT=$(( $COUNT + 1 ))
+}
+
+# Wait for askpass, then set $PID (resp. $BIRTH) to the PID (resp.
+# birth date) of the cryptsetup process with same $CRYPTTAB_NAME.
+wait_for_prompt() {
+ local pid timer num_locked_devices=-1 n
+
+ # wait for the fifo
+ while :; do
+ n=$(count_locked_devices)
+ if [ $n -eq 0 ]; then
+ # all configured devices have been unlocked, we're done
+ exit 0
+ elif [ $num_locked_devices -lt 0 ] || [ $n -lt $num_locked_devices ]; then
+ # reset $timer if a device was unlocked (for instance using
+ # a keyscript) while we were waiting
+ timer=$(( 10 * $TIMEOUT ))
+ fi
+ num_locked_devices=$n
+
+ if pid=$(get_askpass_pid) && [ -p "$PASSFIFO" ]; then
+ break
+ fi
+
+ usleep 100000
+ timer=$(( $timer - 1 ))
+ if [ $timer -le 0 ]; then
+ echo "Error: Timeout reached while waiting for askpass." >&2
+ exit 1
+ fi
+ done
+
+ # find the cryptsetup process with same $CRYPTTAB_NAME
+ local o v
+ for o in NAME TRIED OPTION_tries; do
+ if v="$(grep -z -m1 "^CRYPTTAB_$o=" "/proc/$pid/environ")"; then
+ eval "CRYPTTAB_$o"="\${v#CRYPTTAB_$o=}"
+ else
+ eval unset -v "CRYPTTAB_$o"
+ fi
+ done
+ if [ -z "${CRYPTTAB_NAME:+x}" ] || [ -z "${CRYPTTAB_TRIED:+x}" ]; then
+ return 1
+ fi
+ if ( ! crypttab_find_entry --quiet "$CRYPTTAB_NAME" ); then
+ # use a subshell to avoid polluting our enironment
+ echo "Error: Refusing to process unknown device $CRYPTTAB_NAME" >&2
+ exit 1
+ fi
+
+ for pid in $(pgrep_exe "/sbin/cryptsetup"); do
+ if grep -Fxqz "CRYPTTAB_NAME=$CRYPTTAB_NAME" "/proc/$pid/environ"; then
+ PID=$pid
+ BIRTH=$(stat -c"%Z" "/proc/$PID" 2>/dev/null) || break
+ return 0
+ fi
+ done
+
+ PID=
+ BIRTH=
+ return 1
+}
+
+# Wait until $PID no longer exists or has a birth date greater that
+# $BIRTH (ie was reallocated). Then return with exit value 0 if
+# /dev/mapper/$CRYPTTAB_NAME exists, and with exit value 1 if the
+# maximum number of tries exceeded. Otherwise (if the unlocking
+# failed), return with value 1.
+wait_for_answer() {
+ local timer=$(( 10 * $TIMEOUT )) b
+ while [ -d "/proc/$PID" ] && b=$(stat -c"%Z" "/proc/$PID" 2>/dev/null) && [ $b -le $BIRTH ]; do
+ usleep 100000
+ timer=$(( $timer - 1 ))
+ if [ $timer -le 0 ]; then
+ echo "Error: Timeout reached while waiting for PID $PID." >&2
+ exit 1
+ fi
+ done
+
+ if dm_blkdevname "$CRYPTTAB_NAME" >/dev/null; then
+ echo "cryptsetup: $CRYPTTAB_NAME set up successfully" >&2
+ [ "$UNLOCK_ALL" = y ] && return 0 || exit 0
+ elif [ $(( ${CRYPTTAB_TRIED:-0} + 1 )) -ge ${CRYPTTAB_OPTION_tries:-3} ] &&
+ [ ${CRYPTTAB_OPTION_tries:-3} -gt 0 ]; then
+ echo "cryptsetup: maximum number of tries exceeded for $CRYPTTAB_NAME" >&2
+ exit 1
+ else
+ echo "cryptsetup: cryptsetup failed, bad password or options?" >&2
+ return 1
+ fi
+}
+
+
+if [ -t 0 ] && [ -x "$ASKPASS" ]; then
+ # interactive mode on a TTY: keep trying until all configured devices have
+ # been unlocked or the maximum number of tries exceeded
+ UNLOCK_ALL=y
+ while :; do
+ # note: if the script is not killed before pivot_root it should
+ # exit on its own once $TIMEOUT is reached
+ if ! wait_for_prompt; then
+ usleep 100000
+ continue
+ fi
+ read -rs -p "Please unlock disk $CRYPTTAB_NAME: "; echo
+ printf '%s' "$REPLY" >"$PASSFIFO"
+ wait_for_answer || true
+ done
+else
+ # non-interactive mode: slurp the passphrase from stdin and exit
+ wait_for_prompt || exit 1
+ echo "Please unlock disk $CRYPTTAB_NAME"
+ cat >"$PASSFIFO"
+ wait_for_answer || exit 1
+fi
+
+# vim: set filetype=sh :