Re: [PATCH v4] fixfiles: Unmount temporary bind mounts on SIGINT

[Petr Lautrbach <plautrba@redhat.com>]

Petr Lautrbach <plautrba@redhat.com> writes:

> `fixfiles -M relabel` temporary bind mounts filestems before relabeling
> but it leaves a directory mounted in /tmp/tmp.XXXX when a user hits
> CTRL-C. It means that if the user run `fixfiles -M relabel` again and
> answered Y to clean out /tmp directory, it would remove all data from
> mounted fs.
>
> This patch changes the location where `fixfiles` mounts fs to /run, uses
> private mount namespace via unshare and adds a handler for exit signals
> which tries to umount fs mounted by `fixfiles`.
>
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2125355
>
> Signed-off-by: Petr Lautrbach <plautrba@redhat.com>


Is there anyone who objects?

Petr


> ---
> v2:
>
> - set trap on EXIT instead of SIGINT
>
> v3:
>
> - use /run instead of /tmp for mountpoints
>
> v4:
>
> - use mount namespace as suggested by Christian Göttsche <cgzones@googlemail.com> (September 16) (inbox)
>
>
>  policycoreutils/scripts/fixfiles | 36 +++++++++++++++++++++++++-------
>  1 file changed, 28 insertions(+), 8 deletions(-)
>
> diff --git a/policycoreutils/scripts/fixfiles b/policycoreutils/scripts/fixfiles
> index c72ca0eb9d61..af64a5a567a6 100755
> --- a/policycoreutils/scripts/fixfiles
> +++ b/policycoreutils/scripts/fixfiles
> @@ -207,6 +207,25 @@ rpm -q --qf '[%{FILESTATES} %{FILENAMES}\n]' "$1" | grep '^0 ' | cut -f2- -d ' '
>  [ ${PIPESTATUS[0]} != 0 ] && echo "$1 not found" >/dev/stderr
>  }
>  
> +# unmount tmp bind mount before exit
> +umount_TMP_MOUNT() {
> +	if [ -n "$TMP_MOUNT" ]; then
> +	     umount "${TMP_MOUNT}${m}" || exit 130
> +	     rm -rf "${TMP_MOUNT}" || echo "Error cleaning up."
> +	fi
> +	exit 130
> +}
> +
> +fix_labels_on_mountpoint() {
> +	test -z ${TMP_MOUNT+x} && echo "Unable to find temporary directory!" && exit 1
> +	mkdir -p "${TMP_MOUNT}${m}" || exit 1
> +	mount --bind "${m}" "${TMP_MOUNT}${m}" || exit 1
> +	${SETFILES} ${VERBOSE} ${EXCLUDEDIRS} ${FORCEFLAG} ${THREADS} $* -q ${FC} -r "${TMP_MOUNT}" "${TMP_MOUNT}${m}"
> +	umount "${TMP_MOUNT}${m}" || exit 1
> +	rm -rf "${TMP_MOUNT}" || echo "Error cleaning up."
> +}
> +export -f fix_labels_on_mountpoint
> +
>  #
>  # restore
>  # if called with -n will only check file context
> @@ -252,14 +271,15 @@ case "$RESTORE_MODE" in
>  	        # we bind mount so we can fix the labels of files that have already been
>  	        # mounted over
>  	        for m in `echo $FILESYSTEMSRW`; do
> -	            TMP_MOUNT="$(mktemp -d)"
> -	            test -z ${TMP_MOUNT+x} && echo "Unable to find temporary directory!" && exit 1
> -
> -	            mkdir -p "${TMP_MOUNT}${m}" || exit 1
> -	            mount --bind "${m}" "${TMP_MOUNT}${m}" || exit 1
> -	            ${SETFILES} ${VERBOSE} ${EXCLUDEDIRS} ${FORCEFLAG} ${THREADS} $* -q ${FC} -r "${TMP_MOUNT}" "${TMP_MOUNT}${m}"
> -	            umount "${TMP_MOUNT}${m}" || exit 1
> -	            rm -rf "${TMP_MOUNT}" || echo "Error cleaning up."
> +	          	TMP_MOUNT="$(mktemp -p /run -d fixfiles.XXXXXXXXXX)"
> +	            export SETFILES VERBOSE EXCLUDEDIRS FORCEFLAG THREADS FC TMP_MOUNT m
> +	            if type unshare &> /dev/null; then
> +	                unshare -m bash -x -c "fix_labels_on_mountpoint" $* || exit $?
> +	            else
> +	                trap umount_TMP_MOUNT EXIT
> +	                fix_labels_on_mountpoint $*
> +	                trap EXIT
> +	            fi
>  	        done;
>  	    fi
>  	else
> -- 
> 2.37.3