tests/qemu-iotests/tests/migration-permissions

#!/usr/bin/env python3
# group: migration
#
# 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/>.
#

import os
from subprocess import CalledProcessError

import iotests
from iotests import imgfmt, qemu_img_create, qemu_io


test_img = os.path.join(iotests.test_dir, 'test.img')
mig_sock = os.path.join(iotests.sock_dir, 'mig.sock')


class TestMigrationPermissions(iotests.QMPTestCase):
    def setUp(self):
        qemu_img_create('-f', imgfmt, test_img, '1M')

        # Set up two VMs (source and destination) accessing the same raw
        # image file with a virtio-blk device; prepare the destination for
        # migration with .add_incoming() and enable migration events
        vms = [None, None]
        for i in range(2):
            vms[i] = iotests.VM(path_suffix=f'{i}')
            vms[i].add_blockdev(f'file,node-name=prot,filename={test_img}')
            vms[i].add_blockdev(f'{imgfmt},node-name=fmt,file=prot')
            vms[i].add_device('virtio-blk,drive=fmt')

            if i == 1:
                vms[i].add_incoming(f'unix:{mig_sock}')

            vms[i].launch()

            result = vms[i].qmp('migrate-set-capabilities',
                                capabilities=[
                                    {'capability': 'events', 'state': True}
                                ])
            self.assert_qmp(result, 'return', {})

        self.vm_s = vms[0]
        self.vm_d = vms[1]

    def tearDown(self):
        self.vm_s.shutdown()
        self.vm_d.shutdown()
        try:
            os.remove(mig_sock)
        except FileNotFoundError:
            pass
        os.remove(test_img)

    # Migrate an image in use by a virtio-blk device to another VM and
    # verify that the WRITE permission is unshared both before and after
    # migration
    def test_post_migration_permissions(self):
        # Try to access the image R/W, which should fail because virtio-blk
        # has not been configured with share-rw=on
        emsg = ('ERROR (pre-migration): qemu-io should not be able to '
                'access this image, but it reported no error')
        with self.assertRaises(CalledProcessError, msg=emsg) as ctx:
            qemu_io('-f', imgfmt, '-c', 'quit', test_img)
        if 'Is another process using the image' not in ctx.exception.stdout:
            raise ctx.exception

        # Now migrate the VM
        self.vm_s.qmp('migrate', uri=f'unix:{mig_sock}')
        assert self.vm_s.wait_migration(None)
        assert self.vm_d.wait_migration(None)

        # Try the same qemu-io access again, verifying that the WRITE
        # permission remains unshared
        emsg = ('ERROR (post-migration): qemu-io should not be able to '
                'access this image, but it reported no error')
        with self.assertRaises(CalledProcessError, msg=emsg) as ctx:
            qemu_io('-f', imgfmt, '-c', 'quit', test_img)
        if 'Is another process using the image' not in ctx.exception.stdout:
            raise ctx.exception


if __name__ == '__main__':
    # Only works with raw images because we are testing the
    # BlockBackend permissions; image format drivers may additionally
    # unshare permissions and thus tamper with the result
    iotests.main(supported_fmts=['raw'],
                 supported_protocols=['file'])