tests/qemu-iotests/tests/fuse-allow-other

#!/usr/bin/env bash
# group: rw
#
# Test FUSE exports' allow-other option
#
# Copyright (C) 2021 Red Hat, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# 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/>.
#

seq=$(basename "$0")
echo "QA output created by $seq"

status=1	# failure is the default!

_cleanup()
{
    _cleanup_qemu
    _cleanup_test_img
    rm -f "$EXT_MP"
}
trap "_cleanup; exit \$status" 0 1 2 3 15

# get standard environment, filters and checks
. ../common.rc
. ../common.filter
. ../common.qemu

_supported_fmt generic

_supported_proto file # We create the FUSE export manually

sudo -n -u nobody true || \
    _notrun 'Password-less sudo as nobody required to test allow_other'

# $1: Export ID
# $2: Options (beyond the node-name and ID)
# $3: Expected return value (defaults to 'return')
# $4: Node to export (defaults to 'node-format')
fuse_export_add()
{
    allow_other_not_supported='option allow_other only allowed if'

    output=$(
        success_or_failure=yes _send_qemu_cmd $QEMU_HANDLE \
            "{'execute': 'block-export-add',
              'arguments': {
                  'type': 'fuse',
                  'id': '$1',
                  'node-name': '${4:-node-format}',
                  $2
              } }" \
            "${3:-return}" \
            "$allow_other_not_supported" \
            | _filter_imgfmt
    )

    if echo "$output" | grep -q "$allow_other_not_supported"; then
        # Shut down qemu gracefully so it can unmount the export
        _send_qemu_cmd $QEMU_HANDLE \
            "{'execute': 'quit'}" \
            'return'

        wait=yes _cleanup_qemu

        _notrun "allow_other not supported"
    fi

    echo "$output"
}

EXT_MP="$TEST_DIR/fuse-export"

_make_test_img 64k
touch "$EXT_MP"

echo
echo '=== Test permissions ==='

# $1: allow-other value ('on'/'off'/'auto')
run_permission_test()
{
    _launch_qemu \
        -blockdev \
        "$IMGFMT,node-name=node-format,file.driver=file,file.filename=$TEST_IMG"

    _send_qemu_cmd $QEMU_HANDLE \
        "{'execute': 'qmp_capabilities'}" \
        'return'

    fuse_export_add 'export' \
        "'mountpoint': '$EXT_MP',
         'allow-other': '$1'"

    # Should always work
    echo '(Removing all permissions)'
    chmod 000 "$EXT_MP" 2>&1 | _filter_testdir | _filter_imgfmt
    stat -c 'Permissions post-chmod: %a' "$EXT_MP"

    # Should always work
    echo '(Granting u+r)'
    chmod u+r "$EXT_MP" 2>&1 | _filter_testdir | _filter_imgfmt
    stat -c 'Permissions post-chmod: %a' "$EXT_MP"

    # Should only work with allow-other: Otherwise, no permissions can be
    # granted to the group or others
    echo '(Granting read permissions for everyone)'
    chmod 444 "$EXT_MP" 2>&1 | _filter_testdir | _filter_imgfmt
    stat -c 'Permissions post-chmod: %a' "$EXT_MP"

    echo 'Doing operations as nobody:'
    # Change to TEST_DIR, so nobody will not have to attempt a lookup
    pushd "$TEST_DIR" >/dev/null

    # This is already prevented by the permissions (without allow-other, FUSE
    # exports always have o-r), but test it anyway
    sudo -n -u nobody cat fuse-export >/dev/null

    # If the only problem were the lack of permissions, we should still be able
    # to stat the export as nobody; it should not work without allow-other,
    # though
    sudo -n -u nobody \
        stat -c 'Permissions seen by nobody: %a' fuse-export 2>&1 \
        | _filter_imgfmt

    # To prove the point, revoke read permissions for others and try again
    chmod o-r fuse-export 2>&1 | _filter_testdir | _filter_imgfmt

    # Should fail
    sudo -n -u nobody cat fuse-export >/dev/null
    # Should work with allow_other
    sudo -n -u nobody \
        stat -c 'Permissions seen by nobody: %a' fuse-export 2>&1 \
        | _filter_imgfmt

    popd >/dev/null

    _send_qemu_cmd $QEMU_HANDLE \
        "{'execute': 'quit'}" \
        'return'

    wait=yes _cleanup_qemu
}

# 'auto' should behave exactly like 'on', because 'on' tests that
# allow_other works (otherwise, this test is skipped)
for ao in off on auto; do
    echo
    echo "--- allow-other=$ao ---"

    run_permission_test "$ao"
done

# success, all done
echo "*** done"
rm -f $seq.full
status=0