[PATCH] Bug: race condition in reencrypt_path

[Đoàn Trần Công Danh]

On 2022-12-06 15:44:37+0100, t.fitschen at indiscale.com wrote:
> Sorry, Louis, what is tmpdir? It's not a bash built-in, is it? Did I
> miss something?

tmpdir is a function in password-store.
It will create temporary directories in /dev/shm if available which is
guaranteed to be in devtmpfs on Linux. It also falls back to "mktemp"
on system that lacks /dev/shm and shred the file later.

> I would suggest using `mktemp` which is as secure as gets when you are
> writing unencrypted content on the disk, I suppose. And yes, I think it
> is not ideal to do that.
> 
> Apart from that, I don't know if fixing a gpg bug here is the way to go.
> 
> While I didn't run into this bug yet, I think it is good that you
> found a work-around anyways, because I know that there have been some
> issues with the locking (https://dev.gnupg.org/T5884), so thank you.
> 
> Regards
> Timm
> 
> On Mon, Dec 05, 2022 at 11:16:24PM +0100, Louis Bettens wrote:
> > ---
> >  src/password-store.sh | 12 +++++++++---
> >  1 file changed, 9 insertions(+), 3 deletions(-)
> > 
> > diff --git a/src/password-store.sh b/src/password-store.sh
> > index 22e818f..549848e 100755
> > --- a/src/password-store.sh
> > +++ b/src/password-store.sh
> > @@ -110,6 +110,7 @@ set_gpg_recipients() {
> >  reencrypt_path() {
> >  	local prev_gpg_recipients="" gpg_keys="" current_keys="" index passfile
> >  	local groups="$($GPG $PASSWORD_STORE_GPG_OPTS --list-config --with-colons | grep "^cfg:group:.*")"
> > +	[[ -d "$SECURE_TMPDIR" ]] || die "Error: secure temporary directory not found"
> >  	while read -r -d "" passfile; do
> >  		[[ -L $passfile ]] && continue
> >  		local passfile_dir="${passfile%/*}"
> > @@ -117,7 +118,7 @@ reencrypt_path() {
> >  		passfile_dir="${passfile_dir#/}"
> >  		local passfile_display="${passfile#$PREFIX/}"
> >  		passfile_display="${passfile_display%.gpg}"
> > -		local passfile_temp="${passfile}.tmp.${RANDOM}.${RANDOM}.${RANDOM}.${RANDOM}.--"
> > +		local passfile_temp="${SECURE_TMPDIR}/passfile.tmp.${RANDOM}.${RANDOM}.${RANDOM}.${RANDOM}.--"
> >  
> >  		set_gpg_recipients "$passfile_dir"
> >  		if [[ $prev_gpg_recipients != "${GPG_RECIPIENTS[*]}" ]]; then
> > @@ -133,8 +134,9 @@ reencrypt_path() {
> >  
> >  		if [[ $gpg_keys != "$current_keys" ]]; then
> >  			echo "$passfile_display: reencrypting to ${gpg_keys//$'\n'/ }"
> > -			$GPG -d "${GPG_OPTS[@]}" "$passfile" | $GPG -e "${GPG_RECIPIENT_ARGS[@]}" -o "$passfile_temp" "${GPG_OPTS[@]}" &&
> > -			mv "$passfile_temp" "$passfile" || rm -f "$passfile_temp"
> > +			$GPG -d "${GPG_OPTS[@]}" -o "$passfile_temp" "${GPG_OPTS[@]}" "$passfile" &&
> > +			$GPG -e "${GPG_RECIPIENT_ARGS[@]}" -o "$passfile" "${GPG_OPTS[@]}" "$passfile_temp" ||
> > +			shred "$passfile_temp"
> >  		fi
> >  		prev_gpg_recipients="${GPG_RECIPIENTS[*]}"
> >  	done < <(find "$1" -path '*/.git' -prune -o -path '*/.extensions' -prune -o -iname '*.gpg' -print0)
> > @@ -335,6 +337,8 @@ cmd_init() {
> >  	local gpg_id="$PREFIX/$id_path/.gpg-id"
> >  	set_git "$gpg_id"
> >  
> > +	tmpdir #Defines $SECURE_TMPDIR, required for reencrypt_path
> > +
> >  	if [[ $# -eq 1 && -z $1 ]]; then
> >  		[[ ! -f "$gpg_id" ]] && die "Error: $gpg_id does not exist and so cannot be removed."
> >  		rm -v -f "$gpg_id" || exit 1
> > @@ -624,6 +628,8 @@ cmd_copy_move() {
> >  	local interactive="-i"
> >  	[[ ! -t 0 || $force -eq 1 ]] && interactive="-f"
> >  
> > +	tmpdir #Defines $SECURE_TMPDIR, required for reencrypt_path
> > +
> >  	set_git "$new_path"
> >  	if [[ $move -eq 1 ]]; then
> >  		mv $interactive -v "$old_path" "$new_path" || exit 1
> > -- 
> > 2.38.1
> > 
> 
> -- 
> Herr/Mr Timm Fitschen
> (er/he)
> Development
> 
> T: +49 551 288 76 48-3
> E: t.fitschen at indiscale.com
> I: indiscale.com
> 
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-- 
Danh