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

[Petr Lautrbach <plautrba@redhat.com>]

Christian Göttsche <cgzones@googlemail.com> writes:

> On Fri, 4 Nov 2022 at 11:42, Petr Lautrbach <plautrba@redhat.com> wrote:
>>
>> 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)"
>
> Whitespace issue:
>
> git apply ~/Downloads/v4-fixfiles-Unmount-temporary-bind-mounts-on-SIGINT.patch
> /home/christian/Downloads/v4-fixfiles-Unmount-temporary-bind-mounts-on-SIGINT.patch:137:
> space before tab in indent.
>                         TMP_MOUNT="$(mktemp -p /run -d fixfiles.XXXXXXXXXX)"
> warning: 1 line adds whitespace errors.
>
>> > +                 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 $?
>
> Two issues:
>
> I.
> The `-x` flag make the output unreadable (especially for check/verify).


This is leftover from my debugging. It is not supposed to be there.


> II.
> The option (e.g. `-n` for check/verify) is not passed, should be `-c
> "fix_labels_on_mountpoint $*"`.

I'll fix it.


Thanks!


>> > +                 else
>> > +                     trap umount_TMP_MOUNT EXIT
>> > +                     fix_labels_on_mountpoint $*
>> > +                     trap EXIT
>> > +                 fi
>> >               done;
>> >           fi
>> >       else
>> > --
>> > 2.37.3
>>