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Security fix to setkey

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Now there is no more writing of cleartext secrets in any tempfile,
the last case was in setkey and is now eliminated. Tempfile creation
is cleaner. Related to issue #162
This commit is contained in:
Jaromil 2014-11-22 01:40:26 +01:00
parent 52e80b6042
commit 6bb1385c69
1 changed files with 24 additions and 23 deletions
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tomb
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@ -218,25 +218,28 @@ _ensure_safe_memory check_shm() {
# Mount the tmpfs if the OS doesn't already
[[ -k $shmprefix ]] || {
mkdir -p $shmprefix/$_UID || {
_failure "Fatal error creating a directory for temporary files" }
mkdir $shmprefix
[[ $? = 0 ]] || _failure "Fatal error creating a directory in shared memory."
}
mount -t tmpfs tmpfs $shmprefix/$_UID \
-o nosuid,noexec,nodev,mode=0700,uid=$_UID,gid=$_GID
[[ $? == 0 ]] || {
_failure "Cannot mount tmpfs in ::1 shm path::" $shmprefix }
[[ -r $shmprefix/$_UID ]] || {
mkdir -m 700 $shmprefix/$_UID
[[ $? = 0 ]] || {
_failure "Fatal error creating a directory for temporary files" }
}
# Ensure all temporary files go into a user-specific directory for
# additional safety
mkdir -m 0700 -p $shmprefix/$_UID || {
_failure "Fatal error creating a directory for temporary files" }
# additional safety
# mount -t tmpfs tmpfs $shmprefix/$_UID \
# -o nosuid,noexec,nodev,mode=0700,uid=$_UID,gid=$_GID
# [[ $? == 0 ]] || {
# _failure "Cannot mount tmpfs in ::1 shm path::" $shmprefix }
# Set a global environment variable to ensure zsh will use that
# directory in RAM to keep temporary files by setting an. They
# will be created on demand and deleted as soon as the function
# using them ends.
TMPPREFIX="$shmprefix/$_UID/$RANDOM$RANDOM."
TMPPREFIX="$shmprefix/$_UID"
return 0
@ -272,15 +275,18 @@ _plot() {
# Provide a random filename in shared memory
_tmp_create() {
tfile="${TMPPREFIX}${RANDOM}" # Temporary file
tfile="${TMPPREFIX}/$RANDOM$RANDOM$RANDOM" # Temporary file
umask 066
[[ $? == 0 ]] || {
_failure "Fatal error setting the permission umask for temporary files" }
touch $tfile
[[ $? == 0 ]] || {
_failure "Fatal error creating a temporary file: ::1 temp file::" $tfile }
_failure "Fatal error creating a temporary file: ::1 temp file::" $tfile }
chown $_UID:$_GID $tfile && chmod 0600 $tfile
chown $_UID:$_GID $tfile
[[ $? == 0 ]] || {
_failure "Fatal error setting permissions on temporary file: ::1 temp file::" $tfile }
_failure "Fatal error setting ownership on temporary file: ::1 temp file::" $tfile }
_verbose "Created tempfile: ::1 temp file::" $tfile
TOMBTMP="$tfile"
@ -1608,8 +1614,8 @@ change_tomb_key() {
old_secret=$TOMBSECRET
# luksOpen the tomb (not really mounting, just on the loopback)
print -n - "$old_secret" | \
cryptsetup --key-file - luksOpen ${nstloop} ${mapper}
cryptsetup --key-file <(print -R -n - "$old_secret") \
luksOpen ${nstloop} ${mapper}
[[ $? == 0 ]] || _failure "Unexpected error in luksOpen."
_load_key # Try loading new key from option -k and set TOMBKEYFILE
@ -1627,14 +1633,9 @@ change_tomb_key() {
_failure "No valid password supplied for the new key." }
new_secret=$TOMBSECRET
# Danger zone: due to cryptsetup limitations, in setkey we need
# to write the bare unencrypted key on the tmpfs.
_tmp_create
local newsecretfile=$TOMBTMP
cryptsetup --key-file <(print -R -n - "$old_secret") \
luksChangeKey "$nstloop" <(print -R -n - "$new_secret")
print -n - "$new_secret" >> $newsecretfile
print -n - "$old_secret" | \
cryptsetup --key-file - luksChangeKey "$nstloop" "$newsecretfile"
[[ $? == 0 ]] || _failure "Unexpected error in luksChangeKey."
cryptsetup luksClose "${mapper}" || _failure "Unexpected error in luksClose."