boot: check first partition offset on GRUB devices

Check that the first partition starts at least at 1MiB (2048 cylinders),
as too small first-partition offsets lead to fauilures when doing
grub2-install. The limit (1MiB) has been chosen as it is a common
value set by the disk formatting tools nowadays.

repos/system_upgrade/el7toel8/actors/checkfirstpartitionoffset/actor.py

@@ -0,0 +1,24 @@
+from leapp.actors import Actor
+from leapp.libraries.actor import check_first_partition_offset
+from leapp.models import GRUBDevicePartitionLayout
+from leapp.reporting import Report
+from leapp.tags import ChecksPhaseTag, IPUWorkflowTag
+
+
+class CheckFirstPartitionOffset(Actor):
+    """
+    Check whether the first partition starts at the offset >=1MiB.
+
+    The alignment of the first partition plays role in disk access speeds. Older tools placed the start of the first
+    partition at cylinder 63 (due to historical reasons connected to the INT13h BIOS API). However, grub core
+    binary is placed before the start of the first partition, meaning that not enough space causes bootloader
+    installation to fail. Modern partitioning tools place the first partition at >= 1MiB (cylinder 2048+).
+    """
+
+    name = 'check_first_partition_offset'
+    consumes = (GRUBDevicePartitionLayout,)
+    produces = (Report,)
+    tags = (ChecksPhaseTag, IPUWorkflowTag,)
+
+    def process(self):
+        check_first_partition_offset.check_first_partition_offset()

repos/system_upgrade/el7toel8/actors/checkfirstpartitionoffset/libraries/check_first_partition_offset.py

@@ -0,0 +1,44 @@
+from leapp import reporting
+from leapp.libraries.stdlib import api
+from leapp.models import GRUBDevicePartitionLayout
+
+SAFE_OFFSET_BYTES = 1024*1024  # 1MiB
+
+
+def check_first_partition_offset():
+    problematic_devices = []
+    for grub_dev in api.consume(GRUBDevicePartitionLayout):
+        first_partition = min(grub_dev.partitions, key=lambda partition: partition.start_offset)
+        if first_partition.start_offset <= SAFE_OFFSET_BYTES:
+            problematic_devices.append(grub_dev.device)
+
+    if problematic_devices:
+        summary = (
+            'On the system booting by using BIOS, the in-place upgrade fails '
+            'when upgrading the GRUB2 bootloader if the boot disk\'s embedding area '
+            'does not contain enough space for the core image installation. '
+            'This results in a broken system, and can occur when the disk has been '
+            'partitioned manually, for example using the RHEL 6 fdisk utility.\n\n'
+
+            'The list of devices with small embedding area:\n'
+            '{0}.'
+        )
+        problematic_devices_fmt = ['- {0}'.format(dev) for dev in problematic_devices]
+
+        hint = (
+            'We recommend to perform a fresh installation of the RHEL 8 system '
+            'instead of performing the in-place upgrade.\n'
+            'Another possibility is to reformat the devices so that there is '
+            'at least {0} kiB space before the first partition. '
+            'Note that this operation is not supported and does not have to be '
+            'always possible.'
+        )
+
+        reporting.create_report([
+            reporting.Title('Found GRUB devices with too little space reserved before the first partition'),
+            reporting.Summary(summary.format('\n'.join(problematic_devices_fmt))),
+            reporting.Remediation(hint=hint.format(SAFE_OFFSET_BYTES // 1024)),
+            reporting.Severity(reporting.Severity.HIGH),
+            reporting.Groups([reporting.Groups.BOOT]),
+            reporting.Groups([reporting.Groups.INHIBITOR]),
+        ])

repos/system_upgrade/el7toel8/actors/checkfirstpartitionoffset/tests/test_check_first_partition_offset.py

@@ -0,0 +1,39 @@
+import pytest
+
+from leapp import reporting
+from leapp.libraries.actor import check_first_partition_offset
+from leapp.libraries.common import grub
+from leapp.libraries.common.testutils import create_report_mocked
+from leapp.libraries.stdlib import api
+from leapp.models import GRUBDevicePartitionLayout, PartitionInfo
+from leapp.reporting import Report
+from leapp.utils.report import is_inhibitor
+
+
+@pytest.mark.parametrize(
+    ('devices', 'should_report'),
+    [
+        (
+            [
+                GRUBDevicePartitionLayout(device='/dev/vda',
+                                          partitions=[PartitionInfo(part_device='/dev/vda1', start_offset=32256)])
+            ],
+            True
+        ),
+        (
+            [
+                GRUBDevicePartitionLayout(device='/dev/vda',
+                                          partitions=[PartitionInfo(part_device='/dev/vda1', start_offset=1024*1025)])
+            ],
+            False
+        )
+    ]
+)
+def test_bad_offset_reported(monkeypatch, devices, should_report):
+
+    monkeypatch.setattr(api, 'consume', lambda *args: devices)
+    monkeypatch.setattr(reporting, 'create_report', create_report_mocked())
+
+    check_first_partition_offset.check_first_partition_offset()
+
+    assert bool(reporting.create_report.called) == should_report

repos/system_upgrade/el7toel8/actors/scangrubdevpartitionlayout/actor.py

@@ -0,0 +1,18 @@
+from leapp.actors import Actor
+from leapp.libraries.actor import scan_layout as scan_layout_lib
+from leapp.models import GRUBDevicePartitionLayout, GrubInfo
+from leapp.tags import FactsPhaseTag, IPUWorkflowTag
+
+
+class ScanGRUBDevicePartitionLayout(Actor):
+    """
+    Scan all identified GRUB devices for their partition layout.
+    """
+
+    name = 'scan_grub_device_partition_layout'
+    consumes = (GrubInfo,)
+    produces = (GRUBDevicePartitionLayout,)
+    tags = (FactsPhaseTag, IPUWorkflowTag,)
+
+    def process(self):
+        scan_layout_lib.scan_grub_device_partition_layout()

repos/system_upgrade/el7toel8/actors/scangrubdevpartitionlayout/libraries/scan_layout.py

@@ -0,0 +1,61 @@
+from leapp.libraries.stdlib import api, CalledProcessError, run
+from leapp.models import GRUBDevicePartitionLayout, GrubInfo, PartitionInfo
+
+SAFE_OFFSET_BYTES = 1024*1024  # 1MiB
+
+
+def split_on_space_segments(line):
+    fragments = (fragment.strip() for fragment in line.split(' '))
+    return [fragment for fragment in fragments if fragment]
+
+
+def get_partition_layout(device):
+    try:
+        partition_table = run(['fdisk', '-l', '-u=sectors', device], split=True)['stdout']
+    except CalledProcessError as err:
+        # Unlikely - if the disk has no partition table, `fdisk` terminates with 0 (no err). Fdisk exits with an err
+        # when the device does not exists, or if it is too small to contain a partition table.
+
+        err_msg = 'Failed to run `fdisk` to obtain the partition table of the device {0}. Full error: \'{1}\''
+        api.current_logger().error(err_msg.format(device, str(err)))
+        return None
+
+    table_iter = iter(partition_table)
+
+    for line in table_iter:
+        if not line.startswith('Units'):
+            # We are still reading general device information and not the table itself
+            continue
+
+        unit = line.split('=')[2].strip()  # Contains '512 bytes'
+        unit = int(unit.split(' ')[0].strip())
+        break  # First line of the partition table header
+
+    for line in table_iter:
+        line = line.strip()
+        if not line.startswith('Device'):
+            continue
+
+        part_all_attrs = split_on_space_segments(line)
+        break
+
+    partitions = []
+    for partition_line in table_iter:
+        # Fields:               Device     Boot   Start      End  Sectors Size Id Type
+        # The line looks like: `/dev/vda1  *       2048  2099199  2097152   1G 83 Linux`
+        part_info = split_on_space_segments(partition_line)
+
+        # If the partition is not bootable, the Boot column might be empty
+        part_device = part_info[0]
+        part_start = int(part_info[2]) if len(part_info) == len(part_all_attrs) else int(part_info[1])
+        partitions.append(PartitionInfo(part_device=part_device, start_offset=part_start*unit))
+
+    return GRUBDevicePartitionLayout(device=device, partitions=partitions)
+
+
+def scan_grub_device_partition_layout():
+    grub_devices = api.consume(GrubInfo)
+    for device in grub_devices.orig_devices:
+        dev_info = get_partition_layout(device)
+        if dev_info:
+            api.produce(dev_info)

repos/system_upgrade/el7toel8/actors/scangrubdevpartitionlayout/tests/test_scan_partition_layout.py

@@ -0,0 +1,78 @@
+from collections import namedtuple
+
+import pytest
+
+from leapp.libraries.actor import scan_layout as scan_layout_lib
+from leapp.libraries.common import grub
+from leapp.libraries.common.testutils import create_report_mocked, produce_mocked
+from leapp.libraries.stdlib import api
+from leapp.models import GRUBDevicePartitionLayout, GrubInfo
+from leapp.utils.report import is_inhibitor
+
+Device = namedtuple('Device', ['name', 'partitions', 'sector_size'])
+Partition = namedtuple('Partition', ['name', 'start_offset'])
+
+
+@pytest.mark.parametrize(
+    'devices',
+    [
+        (
+            Device(name='/dev/vda', sector_size=512,
+                   partitions=[Partition(name='/dev/vda1', start_offset=63),
+                               Partition(name='/dev/vda2', start_offset=1000)]),
+            Device(name='/dev/vdb', sector_size=1024,
+                   partitions=[Partition(name='/dev/vdb1', start_offset=100),
+                               Partition(name='/dev/vdb2', start_offset=20000)])
+        ),
+        (
+            Device(name='/dev/vda', sector_size=512,
+                   partitions=[Partition(name='/dev/vda1', start_offset=111),
+                               Partition(name='/dev/vda2', start_offset=1000)]),
+        )
+    ]
+)
+def test_get_partition_layout(monkeypatch, devices):
+    device_to_fdisk_output = {}
+    for device in devices:
+        fdisk_output = [
+            'Disk {0}: 42.9 GB, 42949672960 bytes, 83886080 sectors'.format(device.name),
+            'Units = sectors of 1 * {sector_size} = {sector_size} bytes'.format(sector_size=device.sector_size),
+            'Sector size (logical/physical): 512 bytes / 512 bytes',
+            'I/O size (minimum/optimal): 512 bytes / 512 bytes',
+            'Disk label type: dos',
+            'Disk identifier: 0x0000000da',
+            '',
+            '   Device Boot      Start         End      Blocks   Id  System',
+        ]
+        for part in device.partitions:
+            part_line = '{0}   *     {1}     2099199     1048576   83  Linux'.format(part.name, part.start_offset)
+            fdisk_output.append(part_line)
+
+        device_to_fdisk_output[device.name] = fdisk_output
+
+    def mocked_run(cmd, *args, **kwargs):
+        assert cmd[:3] == ['fdisk', '-l', '-u=sectors']
+        device = cmd[3]
+        output = device_to_fdisk_output[device]
+        return {'stdout': output}
+
+    def consume_mocked(*args, **kwargs):
+        return GrubInfo(orig_devices=[device.name for device in devices])
+
+    monkeypatch.setattr(scan_layout_lib, 'run', mocked_run)
+    monkeypatch.setattr(api, 'produce', produce_mocked())
+    monkeypatch.setattr(api, 'consume', consume_mocked)
+
+    scan_layout_lib.scan_grub_device_partition_layout()
+
+    assert api.produce.called == len(devices)
+
+    dev_name_to_desc = {dev.name: dev for dev in devices}
+
+    for message in api.produce.model_instances:
+        assert isinstance(message, GRUBDevicePartitionLayout)
+        dev = dev_name_to_desc[message.device]
+
+        expected_part_name_to_start = {part.name: part.start_offset*dev.sector_size for part in dev.partitions}
+        actual_part_name_to_start = {part.part_device: part.start_offset for part in message.partitions}
+        assert expected_part_name_to_start == actual_part_name_to_start

repos/system_upgrade/el7toel8/models/partitionlayout.py

@@ -0,0 +1,28 @@
+from leapp.models import fields, Model
+from leapp.topics import SystemInfoTopic
+
+
+class PartitionInfo(Model):
+    """
+    Information about a single partition.
+    """
+    topic = SystemInfoTopic
+
+    part_device = fields.String()
+    """ Partition device """
+
+    start_offset = fields.Integer()
+    """ Partition start - offset from the start of the block device in bytes """
+
+
+class GRUBDevicePartitionLayout(Model):
+    """
+    Information about partition layout of a GRUB device.
+    """
+    topic = SystemInfoTopic
+
+    device = fields.String()
+    """ GRUB device """
+
+    partitions = fields.List(fields.Model(PartitionInfo))
+    """ List of partitions present on the device """