/usr/sbin/aa-remove-unknown is in apparmor 2.12-4ubuntu5.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 | #!/bin/sh
# ----------------------------------------------------------------------
#    Copyright (c) 2017 Canonical Ltd. (All rights reserved)
#
#    This program is free software; you can redistribute it and/or
#    modify it under the terms of version 2 of the GNU General Public
#    License published by the Free Software Foundation.
#
#    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/>.
# ----------------------------------------------------------------------
APPARMOR_FUNCTIONS=/lib/apparmor/functions
APPARMORFS=/sys/kernel/security/apparmor
PROFILES_IFACE="${APPARMORFS}/profiles"
REMOVE="${APPARMORFS}/.remove"
DRY_RUN=0
. $APPARMOR_FUNCTIONS
usage() {
	local progname="$1"
	local rc="$2"
	local msg="usage: ${progname} [options]
Remove profiles unknown to the system
Options:
 -h, --help	Show this help message and exit
 -n		Dry run; don't remove profiles"
	if [ "$rc" -ne 0 ] ; then
		echo "$msg" 1>&2
	else
		echo "$msg"
	fi
	exit "$rc"
}
if [ "$#" -gt 1 ] ; then
	usage "$0" 1
elif [ "$#" -eq 1 ] ; then
	if [ "$1" = "-h" -o "$1" = "--help" ] ; then
		usage "$0" 0
	elif [ "$1" = "-n" ] ; then
		DRY_RUN=1
	else
		usage "$0" 1
	fi
fi
# We can't use a -r test here because while $PROFILES_IFACE is world-readable,
# apparmorfs may still return EACCES from open()
#
# We have to do this check because error checking awk's getline() below is
# tricky and, as is, results in an infinite loop when apparmorfs returns an
# error from open().
if ! IFS= read line < "$PROFILES_IFACE" ; then
	echo "ERROR: Unable to read apparmorfs profiles file" 1>&2
	exit 1
elif [ ! -w "$REMOVE" ] ; then
	echo "ERROR: Unable to write to apparmorfs remove file" 1>&2
	exit 1
fi
# Clean out running profiles not associated with the current profile
# set, excluding the libvirt dynamically generated profiles.
aa_configured=$(mktemp -t aa-XXXXXX)
configured_profile_names > "$aa_configured"
if [ "$?" -ne 0 ] ; then
	echo "ERROR: Unable to enumerate the known profiles" 1>&2
	rm -f "$aa_configured" "$aa_loaded"
	exit 1
fi
aa_loaded=$(mktemp -t aa-XXXXXX)
running_profile_names > "$aa_loaded" || true
if [ "$?" -ne 0 ] ; then
	echo "ERROR: Unable to enumerate the running profiles" 1>&2
	rm -f "$aa_configured" "$aa_loaded"
	exit 1
fi
LC_COLLATE=C comm -2 -3 "$aa_loaded" "$aa_configured" | while read profile ; do
	if [ "$DRY_RUN" -ne 0 ]; then
		echo "Would remove '${profile}'"
	else
		echo "Removing '${profile}'"
		unload_profile "$profile"
	fi
done
ret="$?"
rm -f "$aa_configured" "$aa_loaded"
# will not catch all errors, but still better than nothing
exit $ret
 |